I graduated with a BSc Pharmacy (First Class Honors) degree before pursuing my graduate studies under the excellent tutelage of Professor Malcolm Stevens, inventor of temozolomide. This was followed by postdoctoral training at Stanford University, prior to embarking on liver cancer research in 2003, when I joined the Asian Liver Center’s comprehensive research program. I brought to it my broad expertise encompassing experimental therapeutics, oncology drug discovery and development, genomics, and molecular biology, which appropriately matches the goals of our research on developing diagnostic assays and therapeutic approaches for liver cancer.

Current Role at Stanford

I spearhead multiple projects stemming from the lab’s initial genomics study on liver cancer, with the goal of translating gene expression data of liver cancer patients into improved clinical approaches for the diagnosis and therapy of this fatal disease. I have successfully led inter-disciplinary projects, mentored postdoctoral fellows and visiting scientists, and effectively worked with diverse groups of collaborators from academic and industrial settings. I am committed to help eliminate global health care burden associated with hepatitis B and liver cancer.


Education & Certifications

  • Postdoc, Stanford University, Pediatric Nephrology (2002)
  • Postdoc, Stanford University, Molecular Pharmacology (2001)
  • PhD, University of Nottingham, Nottingham, England, Drug Discovery (1999)
  • Bsc (Honors), National University of Singapore, Singapore, Pharmacy (1995)

Service, Volunteer and Community Work

  • Second Harvest Food Bank


    East Palo Alto

Work Experience

  • Basic Life Science Research Scientist, Department of Surgery (January 2003 - October 2007)

    I set up our lab from scratch, with responsibilities ranging from purchasing supplies and equipment, creating study protocols to be in compliance with Stanford human subjects, animals, and biosafety guidelines, to the hiring and training of our first postdocs. I initiated new projects using our genomics studies of liver cancer as the foundation, and established new collaborations.


    Stanford University, California

  • Visiting Scholar, National Cancer Institute, NIH (June 1998 - December 1998)

    As part of my graduate studies, I spent six months at the National Cancer Institute studying the mechanism of action of our novel compounds. I was fortunate to have Dr. Edward Sausville and Dr. Sherman Stinson as my mentors.


    Bethesda, Maryland, USA

  • Pharmacy Intern, Tan Tock Seng Hospital (June 1995 - June 1996)

    Gained hands-on training as a hospital pharmacist by rotating through different pharmacy sectors, including Inpatient, Outpatient, Retail, and Drug Information.



All Publications

  • Lipid-Based Self-Microemulsion of Niclosamide Achieved Enhanced Oral Delivery and Anti-Tumor Efficacy in Orthotopic Patient-Derived Xenograft of Hepatocellular Carcinoma in Mice. International journal of nanomedicine Liu, Y., Guerrero, D. Q., Lechuga-Ballesteros, D., Tan, M., Ahmad, F., Aleiwi, B., Ellsworth, E. L., Chen, B., Chua, M., So, S. 2024; 19: 2639-2653


    Introduction: We previously identified niclosamide as a promising repurposed drug candidate for hepatocellular carcinoma (HCC) treatment. However, it is poorly water soluble, limiting its tissue bioavailability and clinical application. To overcome these challenges, we developed an orally bioavailable self-microemulsifying drug delivery system encapsulating niclosamide (Nic-SMEDDS).Methods: Nic-SMEDDS was synthesized and characterized for its physicochemical properties, in vivo pharmacokinetics and absorption mechanisms, and in vivo therapeutic efficacy in an orthotopic patient-derived xenograft (PDX)-HCC mouse model. Niclosamide ethanolamine salt (NEN), with superior water solubility, was used as a positive control.Results: Nic-SMEDDS (5.6% drug load) displayed favorable physicochemical properties and drug release profiles in vitro. In vivo, Nic-SMEDDS displayed prolonged retention time and plasma release profile compared to niclosamide or NEN. Oral administration of Nic-SMEDDS to non-tumor bearing mice improved niclosamide bioavailability and Cmax by 4.1- and 1.8-fold, respectively, compared to oral niclosamide. Cycloheximide pre-treatment blocked niclosamide absorption from orally administered Nic-SMEDDS, suggesting that its absorption was facilitated through the chylomicron pathway. Nic-SMEDDS (100 mg/kg, bid) showed greater anti-tumor efficacy compared to NEN (200 mg/kg, qd); this correlated with higher levels (p < 0.01) of niclosamide, increased caspase-3, and decreased Ki-67 in the harvested PDX tissues when Nic-SMEDDS was given. Biochemical analysis at the treatment end-point indicated that Nic-SMEDDS elevated lipid levels in treated mice.Conclusion: We successfully developed an orally bioavailable formulation of niclosamide, which significantly enhanced oral bioavailability and anti-tumor efficacy in an HCC PDX mouse model. Our data support its clinical translation for the treatment of solid tumors.

    View details for DOI 10.2147/IJN.S442143

    View details for PubMedID 38500681

  • Identification and validation of microtubule depolymerizing agent, CYT997, as a potential drug candidate for hepatocellular carcinoma. Liver international : official journal of the International Association for the Study of the Liver Ahmad, F., Ma, L., Wei, W., Liu, Y., Hakim, I., Daugherty, A., Mujahid, S., Radin, A. A., Chua, M., So, S. 2023


    BACKGROUND AND AIMS: Hepatocellular carcinoma (HCC) is a typically fatal malignancy with limited treatment options and poor survival rates, despite recent FDA approvals of newer treatment options. We aim to address this unmet need by using a proprietary computational drug discovery platform that identifies drug candidates with the potential to advance rapidly and successfully through preclinical studies.METHODS: We generated an in silico model of HCC biology to identify the top 10 small molecules with predicted efficacy. The most promising candidate, CYT997, was tested for its invitro effects on cell viability and cell death, colony formation, cell cycle changes, and cell migration/invasion in HCC cells. We used an HCC patient-derived xenograft (PDX) mouse model to assess its invivo efficacy.RESULTS: CYT997 was significantly more cytotoxic against HCC cells than against primary human hepatocytes, and sensitized HCC cells to sorafenib. It arrested cell cycle at the G2/M phase with associated up-regulations of p21, p-MEK1/2, p-ERK, and down-regulation of cyclin B1. Cell apoptosis and senescence-like morphology were also observed. CYT997 inhibited HCC cell migration and invasion, and down-regulated the expressions of acetylated tubulins, beta-tubulin, glypican-3 (GPC3), beta-catenin, and c-Myc. Invivo, CYT997 (20mg/kg, three times weekly by oral gavage) significantly inhibited PDX growth, while being non-toxic to mice. Immunohistochemistry confirmed the down-regulation of GPC3, c-Myc, and Ki-67, supporting its anti-proliferative effect.CONCLUSION: CYT997 is a potentially efficacious and non-toxic drug candidate for HCC therapy. Its ability to down-regulate GPC3, beta-catenin, and c-Myc highlights a novel mechanism of action.

    View details for DOI 10.1111/liv.15756

    View details for PubMedID 37833852

  • Rational design, synthesis and structural characterization of peptides and peptidomimetics to target Hsp90/Cdc37 interaction for treating hepatocellular carcinoma. Computational and structural biotechnology journal Sukumaran, S., Tan, M., Ben-Uliel, S. F., Zhang, H., De Zotti, M., Chua, M. S., So, S. K., Qvit, N. 2023; 21: 3159-3172


    Heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) work together as a molecular chaperone complex to regulate the activity of a multitude of client protein kinases. These kinases belong to a wide array of intracellular signaling networks that mediate multiple cellular processes including proliferation. As a result, Hsp90 and Cdc37 represent innovative therapeutic targets in various cancers (such as leukemia, multiple myeloma, and hepatocellular carcinoma (HCC)) in which their expression levels are elevated. Conventional small molecule Hsp90 inhibitors act by blocking the conserved adenosine triphosphate (ATP) binding site. However, by targeting less conserved sites in a more specific manner, peptides and peptidomimetics (modified peptides) hold potential as more efficacious and less toxic alternatives to the conventional small molecule inhibitors. Using a rational approach, we herein developed bioactive peptides targeting Hsp90/Cdc37 interaction. A six amino acid linear peptide derived from Cdc37, KTGDEK, was designed to target Hsp90. We used in silico computational docking to first define its mode of interaction, and binding orientation, and then conjugated the peptide with a cell penetrating peptide, TAT, and a fluorescent dye to confirm its ability to colocalize with Hsp90 in HCC cells. Based on the parent linear sequence, we developed a peptidomimetics library of pre-cyclic and cyclic derivatives. These peptidomimetics were evaluated for their binding affinity to Hsp90, and bioactivity in HCC cell lines. Among them, a pre-cyclic peptidomimetic demonstrates high binding affinity and bioactivity in HCC cells, causing reduced cell proliferation that is associated with induction of cell apoptosis, and down-regulation of phosphorylated MEK1/2. Overall, this generalized approach of rational design, structural optimization, and cellular validation of 'drug-like' peptidomimetics against Hsp90/Cdc37 offers a feasible and promising way to design novel therapeutic agents for malignancies and other diseases that are dependent on this molecular chaperone complex.

    View details for DOI 10.1016/j.csbj.2023.05.023

    View details for PubMedID 37304004

    View details for PubMedCentralID PMC10250827

  • Deciphering COVID-19 host transcriptomic complexity and variations for therapeutic discovery against new variants. iScience Xing, J., Shankar, R., Ko, M., Zhang, K., Zhang, S., Drelich, A., Paithankar, S., Chekalin, E., Chua, M. S., Rajasekaran, S., Kent Tseng, C. T., Zheng, M., Kim, S., Chen, B. 2022; 25 (10): 105068


    The molecular manifestations of host cells responding to SARS-CoV-2 and its evolving variants of infection are vastly different across the studied models and conditions, imposing challenges for host-based antiviral drug discovery. Based on the postulation that antiviral drugs tend to reverse the global host gene expression induced by viral infection, we retrospectively evaluated hundreds of signatures derived from 1,700 published host transcriptomic profiles of SARS/MERS/SARS-CoV-2 infection using an iterative data-driven approach. A few of these signatures could be reversed by known anti-SARS-CoV-2 inhibitors, suggesting the potential of extrapolating the biology for new variant research. We discovered IMD-0354 as a promising candidate to reverse the signatures globally with nanomolar IC50 against SARS-CoV-2 and its five variants. IMD-0354 stimulated type I interferon antiviral response, inhibited viral entry, and down-regulated hijacked proteins. This study demonstrates that the conserved coronavirus signatures and the transcriptomic reversal approach that leverages polypharmacological effects could guide new variant therapeutic discovery.

    View details for DOI 10.1016/j.isci.2022.105068

    View details for PubMedID 36093376

    View details for PubMedCentralID PMC9439871

  • Exploring Biomolecular Interaction Between the Molecular Chaperone Hsp90 and Its Client Protein Kinase Cdc37 using Field-Effect Biosensing Technology. Journal of visualized experiments : JoVE Lerner, Y., Sukumaran, S., Chua, M., So, S. K., Qvit, N. 2022


    Biomolecular interactions play versatile roles in numerous cellular processesby regulating and coordinating functionally relevant biological events. Biomolecules such as proteins, carbohydrates, vitamins, fatty acids, nucleic acids, and enzymes are fundamental building blocks of living beings; they assemble into complex networks in biosystems to synchronize a myriad of life events. Proteins typically utilize complex interactome networks to carry out their functions; hence it is mandatory to evaluate such interactions to unravel their importance in cells at both cellular and organism levels. Toward this goal, we introduce a rapidly emerging technology, field-effect biosensing (FEB), to determine specific biomolecular interactions. FEB is a benchtop, label-free, and reliable biomolecular detection technique to determine specific interactions and uses high-quality electronic-based biosensors. The FEB technology can monitor interactions in the nanomolar range due to the biocompatible nanomaterials used on its biosensor surface. As a proof of concept, the protein-protein interaction (PPI) between heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) was elucidated. Hsp90 is an ATP-dependent molecular chaperone that plays an essential role in the folding, stability, maturation, and quality control of many proteins, thereby regulating multiple vital cellular functions. Cdc37 is regarded as a protein kinase-specific molecular chaperone, as it specifically recognizes and recruits protein kinases to Hsp90 to regulate their downstream signal transduction pathways. As such, Cdc37 is considered a co-chaperone of Hsp90. The chaperone-kinase pathway (Hsp90/Cdc37 complex) is hyper-activated in multiple malignancies promoting cellular growth; therefore, it is a potential target for cancer therapy. The present study demonstrates the efficiency of FEB technology using the Hsp90/Cdc37 model system. FEB detected a strong PPI between the two proteins (KD values of 0.014 M, 0.053 M, and 0.072 M in three independent experiments). In summary, FEB is a label-free and cost-effective PPI detection platform, which offers fast and accurate measurements.

    View details for DOI 10.3791/63495

    View details for PubMedID 35435890

  • NIR-II imaging of hepatocellular carcinoma based on a humanized anti-GPC3 antibody. RSC medicinal chemistry Shi, H., Huttad, L. V., Tan, M., Liu, H., Chua, M. S., Cheng, Z., So, S. 2022; 13 (1): 90-97


    Liver cancer, of which hepatocellular carcinoma (HCC) is the most common form, is one of the most lethal cancers worldwide. The five-year survival rate for HCC is below 9%, which can be attributed to late diagnosis and limited treatment options at the late stage. Therefore, safe and efficient imaging strategies are urgently needed to facilitate HCC diagnosis and stage evaluation. The development of the second near infrared window (NIR-II, 1000-1700 nm) fluorescence imaging offers the advantages of enhanced resolutions, deeper penetration depth, and less autofluorescence compared to traditional NIR-I window (700-900 nm) imaging. Herein, an HCC targeted NIR-II fluorescent probe, GPC-ICG, was developed by labelling a humanized anti-GPC3 monoclonal antibody with indocyanine green (ICG). Compared to the negative control IgG-ICG probe, the GPC3-ICG probe demonstrated specific GPC3 targeting capability in vitro. And for GPC3 positive Huh-7 tumor bearing mice, the GPC3-ICG probe specifically accumulated in subcutaneous xenografts, with a tumor-background ratio (TBR) of up to 3. The NIR-II imaging of mice organs ex vivo also indicated that GPC3-ICG specifically targeted Huh-7 tumor tissue. Overall, GPC3-ICG is a promising NIR-II probe for GPC3 targeted imaging of HCC.

    View details for DOI 10.1039/d1md00313e

    View details for PubMedID 35224499

    View details for PubMedCentralID PMC8792977

  • A Humanized Anti-GPC3 Antibody for Immuno-Positron Emission Tomography Imaging of Orthotopic Mouse Model of Patient-Derived Hepatocellular Carcinoma Xenografts. Cancers Natarajan, A., Zhang, H., Ye, W., Huttad, L., Tan, M., Chua, M., Gambhir, S. S., So, S. K. 2021; 13 (16)


    Glypican-3 (GPC3) is an attractive diagnostic marker for hepatocellular carcinoma (HCC). We previously reported the potential of an 89Zr-labeled murine anti-GPC3 antibody (clone 1G12) for immunoPET imaging of HCC in orthotopic patient-derived xenograft (PDX) mouse models. We now humanized the murine antibody by complementarity determining region (CDR) grafting, to allow its clinical translation for human use. The engineered humanized anti-GPC3 antibody, clone H3K3, retained comparable binding affinity and specificity to human GPC3. H3K3 was conjugated with desferrioxamine (Df) and radiolabeled with 89Zr to produce the PET/CT tracer 89Zr-Df-H3K3. When injected into GPC3-expressing orthotopic HCC PDX in NOD SCID Gamma (NSG) mice, 89Zr-Df-H3K3 showed specific high uptake into the orthotopic PDX and minimal, non-specific uptake into the non-tumor bearing liver. Specificity was demonstrated by significantly higher uptake of 89Zr-Df-H3K3 into the non-blocked PDX mice, compared with the blocked PDX mice (which received prior injection of 100 mg of unlabeled H3K3). Region of interest (ROI) analysis showed that the PDX/non-tumor liver ratio was highest (mean ± SD: 3.4 ± 0.31) at 168 h post injection; this ratio was consistent with biodistribution studies at the same time point. Thus, our humanized anti-GPC3 antibody, H3K3, shows encouraging potential for use as an immunoPET tracer for diagnostic imaging of HCC patients.

    View details for DOI 10.3390/cancers13163977

    View details for PubMedID 34439132

  • Computational discovery and preclinical validation of therapeutic leads with novel MOAs for hepatocellular carcinoma and pancreatic ductal adenocarcinoma Hakim, I., Chua, M., Wei, W., Ma, L., Noblin, E., So, S., Daugherty, A. C., Heuer, T. S. AMER ASSOC CANCER RESEARCH. 2020
  • Analysis of Infected Host Gene Expression Reveals Repurposed Drug Candidates and Time-Dependent Host Response Dynamics for COVID-19. bioRxiv : the preprint server for biology Xing, J., Shankar, R., Drelich, A., Paithankar, S., Chekalin, E., Dexheimer, T., Chua, M. S., Rajasekaran, S., Tseng, C. K., Chen, B. 2020


    The repurposing of existing drugs offers the potential to expedite therapeutic discovery against the current COVID-19 pandemic caused by the SARS-CoV-2 virus. We have developed an integrative approach to predict repurposed drug candidates that can reverse SARS-CoV-2-induced gene expression in host cells, and evaluate their efficacy against SARS-CoV-2 infection in vitro. We found that 13 virus-induced gene expression signatures computed from various viral preclinical models could be reversed by compounds previously identified to be effective against SARS- or MERS-CoV, as well as drug candidates recently reported to be efficacious against SARS-CoV-2. Based on the ability of candidate drugs to reverse these 13 infection signatures, as well as other clinical criteria, we identified 10 novel candidates. The four drugs bortezomib, dactolisib, alvocidib, and methotrexate inhibited SARS-CoV-2 infection-induced cytopathic effect in Vero E6 cells at < 1 µM, but only methotrexate did not exhibit unfavorable cytotoxicity. Although further improvement of cytotoxicity prediction and bench testing is required, our computational approach has the potential to rapidly and rationally identify repurposed drug candidates against SARS-CoV-2. The analysis of signature genes induced by SARS-CoV-2 also revealed interesting time-dependent host response dynamics and critical pathways for therapeutic interventions (e.g. Rho GTPase activation and cytokine signaling suppression).

    View details for DOI 10.1101/2020.04.07.030734

    View details for PubMedID 32511305

    View details for PubMedCentralID PMC7217282

  • Harnessing big 'omics' data and AI for drug discovery in hepatocellular carcinoma NATURE REVIEWS GASTROENTEROLOGY & HEPATOLOGY Chen, B., Garmire, L., Calvisi, D. F., Chua, M., Kelley, R. K., Chen, X. 2020; 17 (4): 238–51


    Hepatocellular carcinoma (HCC) is the most common form of primary adult liver cancer. After nearly a decade with sorafenib as the only approved treatment, multiple new agents have demonstrated efficacy in clinical trials, including the targeted therapies regorafenib, lenvatinib and cabozantinib, the anti-angiogenic antibody ramucirumab, and the immune checkpoint inhibitors nivolumab and pembrolizumab. Although these agents offer new promise to patients with HCC, the optimal choice and sequence of therapies remains unknown and without established biomarkers, and many patients do not respond to treatment. The advances and the decreasing costs of molecular measurement technologies enable profiling of HCC molecular features (such as genome, transcriptome, proteome and metabolome) at different levels, including bulk tissues, animal models and single cells. The release of such data sets to the public enhances the ability to search for information from these legacy studies and provides the opportunity to leverage them to understand HCC mechanisms, rationally develop new therapeutics and identify candidate biomarkers of treatment response. Here, we provide a comprehensive review of public data sets related to HCC and discuss how emerging artificial intelligence methods can be applied to identify new targets and drugs as well as to guide therapeutic choices for improved HCC treatment.

    View details for DOI 10.1038/s41575-019-0240-9

    View details for Web of Science ID 000508155700002

    View details for PubMedID 31900465

  • An NIR-II/MR dual modal nanoprobe for liver cancer imaging. Nanoscale Ren, Y. n., He, S. n., Huttad, L. n., Chua, M. S., So, S. K., Guo, Q. n., Cheng, Z. n. 2020


    Hepatocellular carcinoma (HCC) is a malignancy of the liver worldwide and surgical resection remains the most effective treatment. However, it is still a great challenge to locate small lesions and define the border of diffused HCC even with the help of preoperative imaging examination. Here, we reported a rare-earth-doped nanoparticle NaGdF4:Nd 5%@NaGdF4@Lips (named Gd-REs@Lips), which simultaneously performed powerful functions in both magnetic resonance imaging (MRI) and second near-infrared fluorescence window imaging (NIR-II, 1000-1700 nm). Imaging studies on orthotopic models with xenografts established from HCC patients indicated that Gd-REs@Lips efficiently worked as a T2-weighted imaging contrast agent to increase the signal intensity difference between liver cancer tissues and surrounding normal liver tissues on MRI, and it can also serve as a negative NIR-II imaging contrast enabling the precise detection of liver cancer. More importantly, benefiting from the high sensitivity of NIR-II imaging, Gd-REs@Lips allowed the visualization of tiny metastasis lesions (2 mm) on the liver surface. It is expected that the dual NIR-II/MRI modal nanoprobe developed holds high potential to fill the gap between the preoperative imaging detection of cancer lesions and intra-operative guidance, and it further brings new opportunities to address HCC-related medical challenges.

    View details for DOI 10.1039/d0nr00075b

    View details for PubMedID 32428058

  • High Inflammatory Factor Grading Predicts Poor Disease-Free Survival in AJCC Stage I-II Hepatocellular Carcinoma Patients After R0 Resection. Cancer management and research Zhang, M., Chua, M. S., Hu, J., Li, H., Zhang, S., Wu, L., Han, B. 2019; 11: 10623-10632


    In this study, we established the inflammatory factor grade system (IFGs) based on the hepatocellular carcinoma (HCC) microenvironment to investigate the role of inflammatory factor grade (IFG) in predicting the prognosis of patients with American Joint Committee on Cancer (AJCC) stage I-II.We enrolled 87 HCC patients with AJCC stage I-II who underwent R0 resection between 2000 and 2012 and had paraffin-embedded specimens. Immunohistochemistry (IHC) was performed to investigate the expression of 12 inflammatory factors and then to establish the IFGs (grade A or B) based on the IHC data. Subsequently, Kaplan-Meier and Cox univariate/multivariate survival analyses were performed to examine the potential prognostic significance.Higher IFG (IFG-B) is significantly associated with greater tumor size (P=0.037), and IFG-B predicts a worse disease-free survival (DFS, P<0.001). Moreover, a platelet count (PLT) ≤100×109/L, tumor size ≥5 cm, poor tumor differentiation, and IFG-B are independent risk factors for DFS.Overall, by establishing a grading system for the level of inflammatory factors in the HCC microenvironment, IFG-B can effectively predict poor DFS in AJCC stage I-II HCC patients after R0 resection.

    View details for DOI 10.2147/CMAR.S230386

    View details for PubMedID 31908534

    View details for PubMedCentralID PMC6927565

  • SOCS5 inhibition induces autophagy to impair metastasis in hepatocellular carcinoma cells via the PI3K/Akt/mTOR pathway. Cell death & disease Zhang, M., Liu, S., Chua, M., Li, H., Luo, D., Wang, S., Zhang, S., Han, B., Sun, C. 2019; 10 (8): 612


    SOCS5 is a member of the suppressor of cytokine signaling (SOCS) protein family with important yet incompletely understood biological functions in cancer. In hepatocellular carcinoma (HCC), controversial tumor-promoting and tumor-suppressive roles of SOCS5 have been reported. Our study aims to unravel novel functions of SOCS5 in HCC, especially that affecting metastasis. We examined the expression levels of SOCS5 in HCC using publicly available datasets, and in our patient cohort, using quantitative real-time PCR, western blotting, and immunohistochemistry. The association of SOCS5 expression with clinical pathological data of HCC patients was examined and that with the mTOR pathway was predicted. We further studied the effects of SOCS5 on PI3K/Akt/mTOR activity; HCC cell autophagy, migration, and invasion; and HCC cell metastasis in vitro and in vivo. We observed that SOCS5 was significantly overexpressed in HCC tissues, compared to adjacent non-tumor liver tissues, in both the public datasets and in our patient cohort. SOCS5 overexpression was significantly and inversely correlated with HCC patient prognosis. Moreover, SOCS5 overexpression promoted HCC cell migration and invasion in vitro by inactivating PI3K/Akt/mTOR-mediated autophagy. Conversely, SOCS5 inhibition suppressed HCC cell migration and invasion in vitro by activating PI3K/Akt/mTOR-mediated autophagy. Dual inhibition of SOCS5 and mTOR further enhanced autophagy and the subsequent anti-metastatic effects on HCC cells. In vivo, stable knockdown of SOCS5 reduced HCC cell metastasis. Overall, our study revealed a novel metastasis-promoting function of SOCS5 in HCC, acting via the PI3K/Akt/mTOR-mediated autophagy pathway. Combined inhibition of SOCS5 and mTOR may be a potential therapeutic approach to inhibit HCC metastasis and prolong patient survival.

    View details for DOI 10.1038/s41419-019-1856-y

    View details for PubMedID 31406106

  • An Automated, Quantitative, and Multiplexed Assay Suitable for Point-of-Care Hepatitis B Virus Diagnostics. Scientific reports Gani, A. W., Wei, W. n., Shi, R. Z., Ng, E. n., Nguyen, M. n., Chua, M. S., So, S. n., Wang, S. X. 2019; 9 (1): 15615


    Hepatitis B virus (HBV) infection has a global reach with high prevalence in resource-limited areas like China and Africa. HBV patients in these areas have limited access to the currently used, costly HBV assays, which are performed in centralized clinical laboratories using single-plexed assays with bulky and expensive instruments. We aim to overcome these limitations by developing a simple and affordable HBV diagnostic platform to allow for timelier diagnosis and intervention of HBV infection. Using giant magnetoresistive (GMR) biosensor chips, we developed an automated and multiplexed quantitative platform for the measurement of a panel of HBV serology markers, including HBV "e" antigen (HBeAg), HBV surface antigen (HBsAg), and the antibody against HBsAg (anti-HBs). Our assay platform was able to detect each HBV marker with high specificity and sensitivity (with three orders of magnitude in dynamic range for each marker). Blinded analysis of HBV patient sera showed excellent correlation between our multiplexed quantitative HBsAg results and the qualitative results obtained using FDA-approved immunoassays, as well as those obtained using quantitative, single-plexed, enzyme-linked immunosorbent assays (ELISAs). The portable, automated, multiplexed, quantitative HBV serology assay platform we designed shows great promise as a more accessible alternative for HBV screening, diagnosis, and treatment monitoring.

    View details for DOI 10.1038/s41598-019-52147-z

    View details for PubMedID 31666635

  • High Inflammatory Factor Grading Predicts Poor Disease-Free Survival in AJCC Stage I-II Hepatocellular Carcinoma Patients After R0 Resection CANCER MANAGEMENT AND RESEARCH Zhang, M., Chua, M., Hu, J., Li, H., Zhang, S., Wu, L., Han, B. 2019; 11: 10623–32
  • A transfer RNA derived small RNA affects translation in rapidly dividing cells and a target for hepatocellular carcinoma Kim, H., Fuchs, G., Wang, S., Wei, W., Zhang, Y., Park, H., Roy-Chaudhuri, B., Li, P., Xu, J., Chu, K., Zhang, F., Chua, M., So, S., Zhang, C., Sarnow, P., Kay, M. A. AMER ASSOC CANCER RESEARCH. 2018
  • Computational Discovery of Niclosamide Ethanolamine, a Repurposed Drug Candidate That Reduces Growth of Hepatocellular Carcinoma Cells In Vitro and in Mice by Inhibiting Cell Division Cycle 37 Signaling. Gastroenterology Chen, B., Wei, W., Ma, L., Yang, B., Gill, R. M., Chua, M., Butte, A. J., So, S. 2017; 152 (8): 2022-2036


    Drug repositioning offers a shorter approval process than new drug development. We therefore searched large public datasets of drug-induced gene expression signatures to identify agents that might be effective against hepatocellular carcinoma (HCC).We searched public databases of messenger RNA expression patterns reported from HCC specimens from patients, HCC cell lines, and cells exposed to various drugs. We identified drugs that might specifically increase expression of genes that are down-regulated in HCCs and reduce expression of genes up-regulated in HCCs using a nonparametric, rank-based pattern-matching strategy based on the Kolmogorov-Smirnov statistic. We evaluated the anti-tumor activity of niclosamide and its ethanolamine salt (NEN) in HCC cell lines (HepG2, Huh7, Hep3B, Hep40, and PLC/PRF/5), primary human hepatocytes, and 2 mouse models of HCC. In one model of HCC, liver tumor development was induced by hydrodynamic delivery of a sleeping beauty transposon expressing an activated form of Ras (v12) and truncated β-catenin (N90). In another mouse model, patient-derived xenografts were established by implanting HCC cells from patients into livers of immunocompromised mice. Tumor growth was monitored by bioluminescence imaging. Tumor-bearing mice were fed a regular chow diet or a chow diet containing niclosamide or NEN. In a separate experiment using patient-derived xenografts, tumor-bearing mice were given sorafenib (the standard of care for patients with advanced HCC), NEN, or niclosamide alone; a combination of sorafenib and NEN; or a combination sorafenib and niclosamide in their drinking water, or regular water (control), and tumor growth was monitored.Based on gene expression signatures, we identified 3 anthelmintics that significantly altered the expression of genes that are up- or down-regulated in HCCs. Niclosamide and NEN specifically reduced the viability of HCC cells: the agents were at least 7-fold more cytotoxic to HCCs than primary hepatocytes. Oral administration of NEN to mice significantly slowed growth of genetically induced liver tumors and patient-derived xenografts, whereas niclosamide did not, coinciding with the observed greater bioavailability of NEN compared with niclosamide. The combination of NEN and sorafenib was more effective at slowing growth of patient-derived xenografts than either agent alone. In HepG2 cells and in patient-derived xenografts, administration of niclosamide or NEN increased expression of 20 genes down-regulated in HCC and reduced expression of 29 genes up-regulated in the 274-gene HCC signature. Administration of NEN to mice with patient-derived xenografts reduced expression of proteins in the Wnt-β-catenin, signal transducer and activator of transcription 3, AKT-mechanistic target of rapamycin, epidermal growth factor receptor-Ras-Raf signaling pathways. Using immunoprecipitation assays, we found NEN to bind cell division cycle 37 protein and disrupt its interaction with heat shock protein 90.In a bioinformatics search for agents that alter the HCC-specific gene expression pattern, we identified the anthelmintic niclosamide as a potential anti-tumor agent. Its ethanolamine salt, with greater bioavailability, was more effective than niclosamide at slowing the growth of genetically induced liver tumors and patient-derived xenografts in mice. Both agents disrupted interaction between cell division cycle 37 and heat shock protein 90 in HCC cells, with concomitant inhibition of their downstream signaling pathways. NEN might be effective for treatment of patients with HCC.

    View details for DOI 10.1053/j.gastro.2017.02.039

    View details for PubMedID 28284560

  • A 3 ' tRNA Derived Small RNA (tsRNA) Affects Translation in Rapidly Dividing Cells and a Target for Hepatocellular Carcinoma Kim, H., Fuchs, G., Wang, S., Wei, W., Zhang, Y., Park, H., Roy-Chaudhuri, B., Zhang, F., Chua, M., So, S., Sarnow, P., Kay, M. A. CELL PRESS. 2017: 34–35
  • A transfer-RNA-derived small RNA regulates ribosome biogenesis. Nature Kim, H. K., Fuchs, G. n., Wang, S. n., Wei, W. n., Zhang, Y. n., Park, H. n., Roy-Chaudhuri, B. n., Li, P. n., Xu, J. n., Chu, K. n., Zhang, F. n., Chua, M. S., So, S. n., Zhang, Q. C., Sarnow, P. n., Kay, M. A. 2017; 552 (7683): 57–62


    Transfer-RNA-derived small RNAs (tsRNAs; also called tRNA-derived fragments) are an abundant class of small non-coding RNAs whose biological roles are not well understood. Here we show that inhibition of a specific tsRNA, LeuCAG3'tsRNA, induces apoptosis in rapidly dividing cells in vitro and in a patient-derived orthotopic hepatocellular carcinoma model in mice. This tsRNA binds at least two ribosomal protein mRNAs (RPS28 and RPS15) to enhance their translation. A decrease in translation of RPS28 mRNA blocks pre-18S ribosomal RNA processing, resulting in a reduction in the number of 40S ribosomal subunits. These data establish a post-transcriptional mechanism that can fine-tune gene expression during different physiological states and provide a potential new target for treating cancer.

    View details for PubMedID 29186115

  • 5-Hydroxymethylcytosine signatures in cell-free DNA provide information about tumor types and stages. Cell research Song, C. X., Yin, S. n., Ma, L. n., Wheeler, A. n., Chen, Y. n., Zhang, Y. n., Liu, B. n., Xiong, J. n., Zhang, W. n., Hu, J. n., Zhou, Z. n., Dong, B. n., Tian, Z. n., Jeffrey, S. S., Chua, M. S., So, S. n., Li, W. n., Wei, Y. n., Diao, J. n., Xie, D. n., Quake, S. R. 2017


    5-Hydroxymethylcytosine (5hmC) is an important mammalian DNA epigenetic modification that has been linked to gene regulation and cancer pathogenesis. Here we explored the diagnostic potential of 5hmC in circulating cell-free DNA (cfDNA) using a sensitive chemical labeling-based low-input shotgun sequencing approach. We sequenced cell-free 5hmC from 49 patients of seven different cancer types and found distinct features that could be used to predict cancer types and stages with high accuracy. Specifically, we discovered that lung cancer leads to a progressive global loss of 5hmC in cfDNA, whereas hepatocellular carcinoma and pancreatic cancer lead to disease-specific changes in the cell-free hydroxymethylome. Our proof-of-principle results suggest that cell-free 5hmC signatures may potentially be used not only to identify cancer types but also to track tumor stage in some cancers.Cell Research advance online publication 18 August 2017; doi:10.1038/cr.2017.106.

    View details for PubMedID 28820176

  • Reversal of cancer gene expression correlates with drug efficacy and reveals therapeutic targets. Nature communications Chen, B. n., Ma, L. n., Paik, H. n., Sirota, M. n., Wei, W. n., Chua, M. S., So, S. n., Butte, A. J. 2017; 8: 16022


    The decreasing cost of genomic technologies has enabled the molecular characterization of large-scale clinical disease samples and of molecular changes upon drug treatment in various disease models. Exploring methods to relate diseases to potentially efficacious drugs through various molecular features is critically important in the discovery of new therapeutics. Here we show that the potency of a drug to reverse cancer-associated gene expression changes positively correlates with that drug's efficacy in preclinical models of breast, liver and colon cancers. Using a systems-based approach, we predict four compounds showing high potency to reverse gene expression in liver cancer and validate that all four compounds are effective in five liver cancer cell lines. The in vivo efficacy of pyrvinium pamoate is further confirmed in a subcutaneous xenograft model. In conclusion, this systems-based approach may be complementary to the traditional target-based approach in connecting diseases to potentially efficacious drugs.

    View details for PubMedID 28699633

    View details for PubMedCentralID PMC5510182

  • Suppression of ATAD2 inhibits hepatocellular carcinoma progression through activation of p53-and p38-mediated apoptotic signaling ONCOTARGET Lu, W., Chua, M., So, S. K. 2015; 6 (39): 41722-41735


    The ATPase family, AAA domain containing 2 (ATAD2) is highly expressed in multiple cancers. We aim to understand the clinical and biological significance of ATAD2 over-expression in hepatocellular carcinoma (HCC), as a means to validate it as a therapeutic target in HCC. We demonstrated that ATAD2 was over-expressed in HCC patients, where high ATAD2 levels were significantly correlated with aggressive phenotypes such as high AFP levels, advanced tumor stages, and vascular invasion. Using RNA interference, suppression of ATAD2 in HCC cell lines decreased cell viability, migration, and invasion, and induced apoptosis in vitro. Furthermore, we identified p53 and p38 as key proteins that mediate apoptosis induced by ATAD2 suppression. In HCC cells, we demonstrated that ATAD2 directly interacted with MKK3/6, which prevented p38 activation and therefore inhibited p38-mediated apoptosis. In vivo, suppression of ATAD2 impaired the growth of HepG2 and Hep3B subcutaneous xenografts, accompanied by enhanced apoptosis and p-p53 and p-p38 levels. Our results validate that ATAD2 is an important negative regulator of apoptosis, and that neutralizing its activity has promising anti-tumor effects in HCC cells.

    View details for Web of Science ID 000366119600024

    View details for PubMedID 26497681

  • NDRG1 promotes growth of hepatocellular carcinoma cells by directly interacting with GSK-3 beta and Nur77 to prevent beta-catenin degradation ONCOTARGET Lu, W., Chua, M., Wei, W., So, S. K. 2015; 6 (30): 29847-29859


    The N-myc downstream regulated gene 1 (NDRG1) is significantly associated with advanced tumor stages and poor survival of hepatocellular carcinoma (HCC), thereby implicating it as a potential target for HCC treatment. We aim to further understand its biological roles in hepatocarcinogenesis, as a means to exploit it for therapeutic purposes. By screening using the ProtoArray® Human Protein Microarrays, we identified glycogen synthase kinase 3β (GSK-3β) and the orphan nuclear receptor (Nur77) as potential interaction partners of NDRG1. These interactions were confirmed in HCC cell lines in vitro by co-immunoprecipitation; and co-localizations of NDRG1 with GSK-3β and Nur77 were observed by immunofluorescence staining. Additionally, high levels of NDRG1 competitively bind to GSK-3β and Nur77 to allow β-catenin to escape degradation, with consequent elevated levels of downstream oncogenic genes. In vivo, we consistently observed that NDRG1 suppression in HCC xenografts decreased β-catenin levels and its downstream target Cyclin D1, with concomitant tumor growth inhibition. Clinically, the over-expression of NDRG1 in HCC patient samples is positively correlated with GSK-3β-9ser (│R│= 0.28, p = 0.01), Nur77 (│R│= 0.42, p < 0.001), and β-catenin (│R│= 0.32, p = 0.003) expressions. In conclusion, we identified GSK-3β and Nur77 as novel interaction partners of NDRG1. These protein-protein interactions regulate the turnover of β-catenin and subsequent downstream signaling mediated by β-catenin in HCC cells, and provides potential targets for future therapeutic interventions.

    View details for Web of Science ID 000363183200105

    View details for PubMedID 26359353

  • Niclosamide ethanolamine inhibits growth of patient-derived hepatocellular carcinoma xenografts Chen, B., Wei, W., Chua, M., Butte, A., So, S. K. WILEY-BLACKWELL. 2015: 459A
  • Identifying novel therapeutic targets in HCC through an integrated transcriptomics and pharmacogenomics approach Chen, B., Ma, L., Chua, M., Butte, A., So, S. K. WILEY-BLACKWELL. 2015: 460A
  • Tankyrase inhibitors attenuate WNT/ß-catenin signaling and inhibit growth of hepatocellular carcinoma cells. Oncotarget Ma, L., Wang, X., Jia, T., Wei, W., Chua, M., So, S. 2015; 6 (28): 25390-25401


    Deregulated WNT/β-catenin signaling contributes to the development of a subgroup of hepatocellular carcinoma (HCC), the second leading cause of cancer deaths worldwide. Within this pathway, the tankyrase enzymes (TNKS1 and TNKS2) degrade AXIN and thereby enhance β-catenin activity. We evaluate TNKS enzymes as potential therapeutic targets in HCC, and the anti-tumor efficacy of tankyrase inhibitors (XAV939, and its novel nitro-substituted derivative WXL-8) in HCC cells. Using semi-quantitative RT-PCR, we found significantly elevated levels of TNKS1/2 mRNA in tumor liver tissues compared to adjacent non-tumor livers, at protein levels only TNKS1 is increased. In HepG2, Huh7cells, siRNA-mediated knockdown suppression of endogenous TNKS1 and TNKS2 reduced cell proliferation, together with decreased nuclear β-catenin levels. XAV939 and WXL-8 inhibited cell proliferation and colony formation in HepG2, Huh7, and Hep40 cells (p < 0.05), with stabilization of AXIN1 and AXIN2, and decreased β-catenin protein levels. XAV939 and WXL-8 also attenuated rhWNT3A-induced TOPflash luciferase reporter activity in HCC cells, indicating reduced β-catenin transcriptional activity, consistent with decreased nuclear β-catenin levels. In vivo, intra-tumor injections of XAV939 or WXL-8 significantly inhibited the growth of subcutaneous HepG2 xenografts (P < 0.05). We suggest that tankyrase inhibition is a potential therapeutic approach for treating a subgroup HCC with aberrant WNT/β-catenin signaling pathway.

    View details for DOI 10.18632/oncotarget.4455

    View details for PubMedID 26246473

  • Suppressing the CDC37 cochaperone in hepatocellular carcinoma cells inhibits cell cycle progression and cell growth. Liver international Wang, Z., Wei, W., Sun, C. K., Chua, M., So, S. 2015; 35 (4): 1403-1415


    The molecular cochaperone CDC37 regulates the activities of multiple protein kinases, and is an attractive broad-spectrum target in many types of cancers in which it is over-expressed. This study investigates the antitumour effects of inhibiting CDC37 in human hepatocellular carcinoma (HCC).A total of 91 patients were enrolled for CDC37 mRNA detection by using quantitative real-time PCR. Cell proliferation, gene expression changes and tumourigenicity were determined by targeting CDC37 using RNA interference in human hepatoma cell lines.We confirmed the significant over-expression of CDC37 transcript and protein in HBV-associated HCC patients. Using a CDC37-specific small oligo-siRNA, we silenced CDC37 expression in HepG2 and Huh7 hepatoma cell lines, and observed inhibition of in vitro cell proliferation, cell cycle arrest at the G1 phase, and enhanced apoptosis. Specifically, we found concomitant down-regulation of Cyclin D1, CDK4, and pRB (S807/811 and S795) upon CDC37 suppression, which could mediate the arrest of cell cycle progression at the G1 phase. Gene expression profiling further identified several genes involved in cell proliferation, cell cycle progression, and apoptosis that are regulated by CDC37 suppression. Huh7 cells with stable knockdown of CDC37 showed decreased in vitro colony formation ability, and significantly slowed xenograft growth in vivo.On the basis of the observed antitumour effects of inhibiting CDC37 expression, we propose that CDC37 is a promising therapeutic target in HCC. Its ability to regulate multiple pathways makes it potentially valuable in treating the heterogeneous subtypes of this malignancy.

    View details for DOI 10.1111/liv.12651

    View details for PubMedID 25098386

  • Imaging of hepatocellular carcinoma patient-derived xenografts using Zr-89-labeled anti-glypican-3 monoclonal antibody BIOMATERIALS Yang, X., Liu, H., Sun, C. K., Natarajan, A., Hu, X., Wang, X., Allegretta, M., Guttmann, R. D., Gambhir, S. S., Chua, M., Cheng, Z., So, S. K. 2014; 35 (25): 6964-6971


    Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention.

    View details for DOI 10.1016/j.biomaterials.2014.04.089

    View details for Web of Science ID 000338386800028

  • Novel celastrol derivatives inhibit the growth of hepatocellular carcinoma patient-derived xenografts. Oncotarget Wei, W., Wu, S., Wang, X., Sun, C. K., Yang, X., Yan, X., Chua, M., So, S. 2014; 5 (14): 5819-5831


    The molecular co-chaperone CDC37 is over-expressed in hepatocellular carcinoma (HCC) cells, where it functions with HSP90 to regulate the activity of protein kinases in multiple oncogenic signaling pathways that contribute towards hepatocarcinogenesis. Disruption of these signaling pathways via inhibition of HSP90/CDC37 interaction is therefore a rational therapeutic approach. We evaluated the anti-tumor effects of celastrol, pristimerin, and two novel derivatives (cel-D2, and cel-D7) on HCC cell lines in vitro and on orthotopic HCC patient-derived xenografts in vivo. All four compounds preferentially inhibited viability of HCC cells in vitro,and significantly inhibited the growth of three orthotopic HCC patient-derived xenografts in vivo; with the novel derivatives cel-D2 and cel-D7 exhibiting lower toxicity. All four compounds also induced cell apoptosis; and promoted degradation and inhibited phosphorylation of protein kinases in the Raf/MEK/ERK and PI3K/AKT/mTOR signaling pathways. We demonstrated that HSP90/CDC37 antagonists are potentially broad spectrum agents that might be beneficial for treating the heterogeneous subtypes of HCC, either as monotherapy, or in combination with other chemotherapeutic agents.

    View details for PubMedID 25051375

  • Suppressing N-Myc downstream regulated gene 1 reactivates senescence signaling and inhibits tumor growth in hepatocellular carcinoma. Carcinogenesis Lu, W., Chua, M., So, S. K. 2014; 35 (4): 915-922


    Hepatocellular carcinoma (HCC) is the fifth most lethal malignancy worldwide with no curative therapies. To discover potentially novel therapeutic targets for HCC, we previously studied the gene expression profiles of HCC patients and identified that significant upregulation of N-Myc downstream regulated gene 1 (NDRG1) is associated with more aggressive phenotypes and poorer overall survival of HCC patients. In this study, we further used a loss-of-function approach (RNA interference) to understand the role of NDRG1 in hepatocarcinogenesis. We found that suppression of NDRG1 significantly impaired HCC cell growth through inducing extensive cellular senescence of HCC cells both in vitro and in vivo, accompanied by cell cycle arrest at the G1 phase. The observed antitumor effects of NDRG1 suppression were correlated with activation of major senescence-associated signaling pathways, such as upregulation of tumor suppressors p53, p21 and p16, and decreased phosphorylated Rb. To obtain further insights into the clinical significance of NDRG1-modulated senescence in HCC patients, immunohistochemistry staining of 92 cases of HCC patients was done. We found that high NDRG1 expression (n = 66) is associated with low p21 (n = 82; P < 0.001) and low p16 (n = 86; P < 0.001) levels. In conclusion, this study demonstrated that NDRG1 is a potential therapeutic target for HCC because its suppression triggers senescence of HCC cells through activating glycogen synthase kinase-3β-p53 pathway, thereby inhibiting tumor progression.

    View details for DOI 10.1093/carcin/bgt401

    View details for PubMedID 24302615

  • Epigenetics in hepatocellular carcinoma: An update and future therapy perspectives WORLD JOURNAL OF GASTROENTEROLOGY Ma, L., Chua, M., Andrisani, O., So, S. 2014; 20 (2): 333-345


    Hepatocellular carcinoma (HCC), the predominant form of adult liver malignancies, is a global health concern. Its dismal prognosis has prompted recent significant advances in the understanding of its etiology and pathogenesis. The deregulation of epigenetic mechanisms, which maintain heritable gene expression changes and chromatin organization, is implicated in the development of multiple cancers, including HCC. This review summarizes the current knowledge of epigenetic mechanisms in the pathogenesis of HCC, with an emphasis on HCC mediated by chronic hepatitis B virus infection. This review also discusses the encouraging outcomes and lessons learnt from epigenetic therapies for hematological and other solid cancers, and highlights the future potential of similar therapies in the treatment of HCC.

    View details for DOI 10.3748/wjg.v20.i2.333

    View details for Web of Science ID 000330856100001

    View details for PubMedCentralID PMC3923010

  • Targeting activated Wnt/beta-catenin signaling by XAV939 and its derivative WXL-8 in hepatocellular carcinoma Ma, L., Wang, X., Wei, W., Chua, M., So, S. K. WILEY-BLACKWELL. 2014: 819A–820A
  • Molecular imaging of hepatocellular carcinoma xenografts with epidermal growth factor receptor targeted affibody probes. BioMed research international Zhao, P., Yang, X., Qi, S., Liu, H., Jiang, H., Hoppmann, S., Cao, Q., Chua, M., So, S. K., Cheng, Z. 2013; 2013: 759057-?


    Hepatocellular carcinoma (HCC) is a highly aggressive and lethal cancer. It is typically asymptomatic at the early stage, with only 10%-20% of HCC patients being diagnosed early enough for appropriate surgical treatment. The delayed diagnosis of HCC is associated with limited treatment options and much lower survival rates. Therefore, the early and accurate detection of HCC is crucial to improve its currently dismal prognosis. The epidermal growth factor receptor (EGFR) has been reported to be involved in HCC tumorigenesis and to represent an attractive target for HCC imaging and therapy. In this study, an affibody molecule, Ac-Cys-ZEGFR:1907, targeting the extracellular domain of EGFR, was used for the first time to assess its potential to detect HCC xenografts. By evaluating radio- or fluorescent-labeled Ac-Cys-ZEGFR:1907 as a probe for positron emission tomography (PET) or optical imaging of HCC, subcutaneous EGFR-positive HCC xenografts were found to be successfully imaged by the PET probe. Thus, affibody-based PET imaging of EGFR provides a promising approach for detecting HCC in vivo.

    View details for DOI 10.1155/2013/759057

    View details for PubMedID 23710458

    View details for PubMedCentralID PMC3654646

  • Assessment and comparison of magnetic nanoparticles as MRI contrast agents in a rodent model of human hepatocellular carcinoma CONTRAST MEDIA & MOLECULAR IMAGING Bu, L., Xie, J., Chen, K., Huang, J., Aguilar, Z. P., Wang, A., Sun, K. W., Chua, M., So, S., Cheng, Z., Eden, H. S., Shen, B., Chen, X. 2012; 7 (4): 363-372


    The purpose of this study was to synthesize, characterize and tailor the surface properties of magnetic nanoparticles with biocompatible copolymer coatings and to evaluate the efficiency of the resulting nanoconjugates as magnetic resonance imaging (MRI) contrast agents for liver imaging. Magnetic nanoparticles with core diameters of 10 and 30 nm were synthesized by pyrolysis and were subsequently coated with a copolymer containing either carboxyl (SHP) or methoxy groups as termini. All four formulas, and ferumoxides (Feridex I.V.(®)), were individually injected intravenously into separate, normal Balb/C mice (at 2.5, 1.0 and 0.56 mg Fe kg(-1)), and the animals underwent T(2)-weighted MRI at multiple time points post injection (p.i.) to evaluate the hepatic uptake and clearance. Furthermore, we compared the abilities of the new formulas and Feridex to detect tumors in an orthotropic Huh7 tumor model. Transmission electron microscopy (TEM) revealed a narrow size distribution of both the 10 and 30 nm nanoparticles, in contrast to a wide size distribution of Feridex. MTT, apoptosis and cyclin/DNA flow cytometry assays showed that the polymer coated nanoparticles had no adverse effect on cell growth. Among all the tested formulas, including Feridex, SHP-30 showed the highest macrophage uptake at the in vitro level. In vivo MRI studies on normal mice confirmed the superiority of SHP-30 in inducing hypointensities in the liver tissue, especially at clinical dose (0.56 mg Fe kg(-1)) and 3 T field. SHP-30 showed better contrast-to-noise ratio than Feridex on the orthotropic Huh7 tumor model. SHP-30 was found to be an efficient contrast agent for liver MR imaging. The success of this study suggests that, by improving the synthetic approach and by tuning the surface properties of IONPs, one can arrive at better formulas than Feridex for clinical practice.

    View details for DOI 10.1002/cmmi.494

    View details for Web of Science ID 000304665100002

    View details for PubMedID 22649042

  • Identification of a 14-gene signature that predicts survival in colorectal cancer with liver metastasis 48th Annual Meeting of the American-Society-of-Clinical-Oncology (ASCO) Chung, J. L., Pollack, J., Chua, M., So, S., Lin, C., Lin, A. Y. AMER SOC CLINICAL ONCOLOGY. 2012
  • The CD47-signal regulatory protein alpha (SIRPa) interaction is a therapeutic target for human solid tumors PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Willingham, S. B., Volkmer, J., Gentles, A. J., Sahoo, D., Dalerba, P., Mitra, S. S., Wang, J., Contreras-Trujillo, H., Martin, R., Cohen, J. D., Lovelace, P., Scheeren, F. A., Chao, M. P., Weiskopf, K., Tang, C., Volkmer, A. K., Naik, T. J., Storm, T. A., Mosley, A. R., Edris, B., Schmid, S. M., Sun, C. K., Chua, M., Murillo, O., Rajendran, P., Cha, A. C., Chin, R. K., Kim, D., Adorno, M., Raveh, T., Tseng, D., Jaiswal, S., Enger, P. O., Steinberg, G. K., Li, G., So, S. K., Majeti, R., Harsh, G. R., van de Rijn, M., Teng, N. N., Sunwoo, J. B., Alizadeh, A. A., Clarke, M. F., Weissman, I. L. 2012; 109 (17): 6662-6667


    CD47, a "don't eat me" signal for phagocytic cells, is expressed on the surface of all human solid tumor cells. Analysis of patient tumor and matched adjacent normal (nontumor) tissue revealed that CD47 is overexpressed on cancer cells. CD47 mRNA expression levels correlated with a decreased probability of survival for multiple types of cancer. CD47 is a ligand for SIRPα, a protein expressed on macrophages and dendritic cells. In vitro, blockade of CD47 signaling using targeted monoclonal antibodies enabled macrophage phagocytosis of tumor cells that were otherwise protected. Administration of anti-CD47 antibodies inhibited tumor growth in orthotopic immunodeficient mouse xenotransplantation models established with patient tumor cells and increased the survival of the mice over time. Anti-CD47 antibody therapy initiated on larger tumors inhibited tumor growth and prevented or treated metastasis, but initiation of the therapy on smaller tumors was potentially curative. The safety and efficacy of targeting CD47 was further tested and validated in immune competent hosts using an orthotopic mouse breast cancer model. These results suggest all human solid tumor cells require CD47 expression to suppress phagocytic innate immune surveillance and elimination. These data, taken together with similar findings with other human neoplasms, show that CD47 is a commonly expressed molecule on all cancers, its function to block phagocytosis is known, and blockade of its function leads to tumor cell phagocytosis and elimination. CD47 is therefore a validated target for cancer therapies.

    View details for DOI 10.1073/pnas.1121623109

    View details for PubMedID 22451913

  • Therapeutic targeting of glypican-3 using TGF-beta 2 as a novel treatment approach for HCC Sun, C. K., Chua, M., So, S. AMER ASSOC CANCER RESEARCH. 2012
  • OPTICAL IMAGING OF LIVER CARCINOMA XENOGRAFTS USING EPIDERMAL GROWTH FACTOR RECEPTOR TARGETED FLUORESCENTLY LABELED AFFIBODY 62nd Annual Meeting of the American-Association-for-the-Study-of-Liver-Diseases (AASLD) Zhao, P., Yang, X., Qi, S., Cao, Q., Chua, M., Wang, J., So, S., Cheng, Z. WILEY-BLACKWELL. 2011: 894A–894A
  • Suppression of Glypican 3 Inhibits Growth of Hepatocellular Carcinoma Cells through Up-Regulation of TGF-beta 2 NEOPLASIA Sun, C. K., Chua, M., He, J., So, S. K. 2011; 13 (8): 735-U111


    Glypican 3 (GPC3) is a valuable diagnostic marker and a potential therapeutic target in hepatocellular carcinoma (HCC). To evaluate the efficacy of targeting GPC3 at the translational level, we used RNA interference to examine the biologic and molecular effects of GPC3 suppression in HCC cells in vitro and in vivo. Transfection of Huh7 and HepG2 cells with GPC3-specific small interfering RNA (siRNA) inhibited cell proliferation (P < .001) together with cell cycle arrest at the G(1) phase, down-regulation of antiapoptotic protein (Bcl-2, Bcl-xL, and Mcl-1), and replicative senescence. Gene expression analysis revealed that GPC3 suppression significantly correlated with transforming growth factor beta receptor (TGFBR) pathway (P = 4.57e-5) and upregulated TGF-β2 at both RNA and protein levels. The effects of GPC3 suppression by siRNA can be recapitulated by addition of human recombinant TGF-β2 to HCC cells in culture, suggesting the possible involvement of TGF-β2 in growth inhibition of HCC cells. Cotransfection of siRNA-GPC3 with siRNA-TGF-β2 partially attenuated the effects of GPC3 suppression on cell proliferation, cell cycle progression, apoptosis, and replicative senescence, confirming the involvement of TGF-β2 in siRNA-GPC3-mediated growth suppression. In vivo, GPC3 suppression significantly inhibited the growth of orthotopic xenografts of Huh7 and HepG2 cells (P < .05), accompanied by increased TGF-β2 expression, reduced cell proliferation (observed by proliferating cell nuclear antigen staining), and enhanced apoptosis (by TUNEL staining). In conclusion, molecular targeting of GPC3 at the translational level offers an effective option for the clinical management of GPC3-positive HCC patients.

    View details for DOI 10.1593/neo.11664

    View details for Web of Science ID 000295942500008

    View details for PubMedID 21847365

    View details for PubMedCentralID PMC3156664

  • Hot Topic: Recent Advances Into the Molecular Mechanisms and Therapeutic Targeting of Hepatocellular Carcinoma ANTI-CANCER AGENTS IN MEDICINAL CHEMISTRY Chua, M., Wang, L. 2011; 11 (6): 491-492

    View details for Web of Science ID 000292761600001

    View details for PubMedID 21574957

  • In vivo MRSI of hyperpolarized [1-C-13]pyruvate metabolism in rat hepatocellular carcinoma NMR IN BIOMEDICINE Darpolor, M. M., Yen, Y., Chua, M., Xing, L., Clarke-Katzenberg, R. H., Shi, W., Mayer, D., Josan, S., Hurd, R. E., Pfefferbaum, A., Senadheera, L., So, S., Hofmann, L. V., Glazer, G. M., Spielman, D. M. 2011; 24 (5): 506-513


    Hepatocellular carcinoma (HCC), the primary form of human adult liver malignancy, is a highly aggressive tumor with average survival rates that are currently less than 1 year following diagnosis. Most patients with HCC are diagnosed at an advanced stage, and no efficient marker exists for the prediction of prognosis and/or response(s) to therapy. We have reported previously a high level of [1-(13)C]alanine in an orthotopic HCC using single-voxel hyperpolarized [1-(13)C]pyruvate MRS. In the present study, we implemented a three-dimensional MRSI sequence to investigate this potential hallmark of cellular metabolism in rat livers bearing HCC (n = 7 buffalo rats). In addition, quantitative real-time polymerase chain reaction was used to determine the mRNA levels of lactate dehydrogenase A, nicotinamide adenine (phosphate) dinucleotide dehydrogenase quinone 1 and alanine transaminase. The enzyme levels were significantly higher in tumor than in normal liver tissues within each rat, and were associated with the in vivo MRSI signal of [1-(13)C]alanine and [1-(13)C]lactate after a bolus intravenous injection of [1-(13)C]pyruvate. Histopathological analysis of these tumors confirmed the successful growth of HCC as a nodule in buffalo rat livers, revealing malignancy and hypervascular architecture. More importantly, the results demonstrated that the metabolic fate of [1-(13)C]pyruvate conversion to [1-(13)C]alanine significantly superseded that of [1-(13)C]pyruvate conversion to [1-(13)C]lactate, potentially serving as a marker of HCC tumors.

    View details for DOI 10.1002/nbm.1616

    View details for Web of Science ID 000291597200009

    View details for PubMedID 21674652

    View details for PubMedCentralID PMC3073155

  • Comparative Profiling of Primary Colorectal Carcinomas and Liver Metastases Identifies LEF1 as a Prognostic Biomarker PLOS ONE Lin, A. Y., Chua, M., Choi, Y., Yeh, W., Kim, Y. H., Azzi, R., Adams, G. A., Sainani, K., van de Rijn, M., So, S. K., Pollack, J. R. 2011; 6 (2)


    We sought to identify genes of clinical significance to predict survival and the risk for colorectal liver metastasis (CLM), the most common site of metastasis from colorectal cancer (CRC).We profiled gene expression in 31 specimens from primary CRC and 32 unmatched specimens of CLM, and performed Significance Analysis of Microarrays (SAM) to identify genes differentially expressed between these two groups. To characterize the clinical relevance of two highly-ranked differentially-expressed genes, we analyzed the expression of secreted phosphoprotein 1 (SPP1 or osteopontin) and lymphoid enhancer factor-1 (LEF1) by immunohistochemistry using a tissue microarray (TMA) representing an independent set of 154 patients with primary CRC.Supervised analysis using SAM identified 963 genes with significantly higher expression in CLM compared to primary CRC, with a false discovery rate of <0.5%. TMA analysis showed SPP1 and LEF1 protein overexpression in 60% and 44% of CRC cases, respectively. Subsequent occurrence of CLM was significantly correlated with the overexpression of LEF1 (chi-square p = 0.042), but not SPP1 (p = 0.14). Kaplan Meier analysis revealed significantly worse survival in patients with overexpression of LEF1 (p<0.01), but not SPP1 (p = 0.11). Both univariate and multivariate analyses identified stage (p<0.0001) and LEF1 overexpression (p<0.05) as important prognostic markers, but not tumor grade or SPP1.Among genes differentially expressed between CLM and primary CRC, we demonstrate overexpression of LEF1 in primary CRC to be a prognostic factor for poor survival and increased risk for liver metastasis.

    View details for DOI 10.1371/journal.pone.0016636

    View details for Web of Science ID 000287761700013

    View details for PubMedID 21383983

    View details for PubMedCentralID PMC3044708

  • Soluble Frizzled-7 receptor inhibits Wnt signaling and sensitizes hepatocellular carcinoma cells towards doxorubicin MOLECULAR CANCER Wei, W., Chua, M., Grepper, S., So, S. K. 2011; 10


    There are limited therapeutic options for hepatocellular carcinoma (HCC), the most common liver malignancy worldwide. Recent studies have identified the Frizzled-7 receptor (FZD7), important for activation of Wnt-mediated signaling, as a potential therapeutic target for HCC and other cancers.We hypothesized that the extracellular domain of FZD7 (sFZD7) would be a clinically more relevant therapeutic modality than previously studied approaches to target FZD7. We expressed and purified sFZD7 from E. coli, and tested its functional activity to interact with Wnt3, its ability to inhibit Wnt3-mediated signaling, and its potential for combinatorial therapy in HCC.sFZD7 pulled down Wnt3 from Huh7 cells, and decreased β-catenin/Tcf4 transcriptional activity in HCC cells. In vitro, sFZD7 dose-dependently decreased viability of three HCC cell lines (HepG2, Hep40, and Huh7, all with high FZD7 and Wnt3 mRNA), but had little effect on normal hepatocytes from three donors (all with low level FZD7 and Wnt3 mRNA). When combined with doxorubicin, sFZD7 enhanced the growth inhibitory effects of doxorubicin against HCC cells in vitro, and against Huh7 xenografts in vivo. Reduced expressions of c-Myc, cyclin D1, and survivin were observed in vitro and in vivo. Additionally, sFZD7 altered the levels of phosphorylated AKT and ERK1/2 induced by doxorubicin treatment in vitro, suggesting that several critical pathways are involved in the chemosensitizing effect of sFZD7.We propose that sFZD7 is a feasible therapeutic agent with specific activity, which can potentially be combined with other chemotherapeutic agents for the improved management of HCC.

    View details for DOI 10.1186/1476-4598-10-16

    View details for Web of Science ID 000288094200001

    View details for PubMedID 21314951

    View details for PubMedCentralID PMC3050858

  • Rodent-specific hypoxia response elements enhance PAI-1 expression through HIF-1 or HIF-2 in mouse hepatoma cells INTERNATIONAL JOURNAL OF ONCOLOGY Ahn, Y., Chua, M., Whitlock, J. P., Shin, Y., Song, W., Kim, Y., Eom, C., An, W. G. 2010; 37 (6): 1627-1638


    Plasminogen activator inhibitor-1 (PAI-1) is an important regulator of numerous pathophysiological processes such as inflammation, thrombosis, angiogenesis and tumor metastasis. Its expression is induced by hypoxia at the transcriptional level, via the hypoxia inducible factor-1 (HIF-1) or -2 (HIF-2). In this study, we elucidated the mechanism of transcriptional regulation of mouse PAI-1 gene by hypoxia in mouse hepatoma cells. We searched for hypoxia response elements (HREs) of murine PAI-1 promoter using several molecular biological assays. DNAse I hypersensitivity assay first suggested that PAI-1 gene expression is up-regulated by protein-DNA interactions at the -3.6- and -3-kb upstream regions of the PAI-1 gene transcription start site. An approximately 6.4-kb region of DNA containing the 5'-flanking promoter region of the PAI-1 gene was isolated, mapped, and cloned into reporter gene assay vectors and sequenced. Luciferase reporter gene assay subsequently identified two functional HREs, located around -3.6 kb of the 5'-flanking promoter region of PAI-1 gene that were responsible for the enhancement of luciferase reporter gene activity. Mutation of the HREs in this fragment abolished luciferase reporter gene activity. Finally, in vitro and in vivo protein-DNA interaction assays confirmed binding of the two HREs to HIF-1 or HIF-2 protein. Our results show that two HREs located around -3.6 kb of the 5'-flanking promoter region of the mouse PAI-1 gene function as hypoxia enhancers, which, alongside other regulatory regions, control PAI-1 gene transcription by HIF-1 or HIF-2 under hypoxic environments in mouse hepatoma cells.

    View details for DOI 10.3892/ijo_00000817

    View details for Web of Science ID 000284922700030

    View details for PubMedID 21042733

  • Small molecule antagonists of Tcf4/beta-catenin complex inhibit the growth of HCC cells in vitro and in vivo INTERNATIONAL JOURNAL OF CANCER Wei, W., Chua, M., Grepper, S., So, S. 2010; 126 (10): 2426-2436


    Hepatocellular carcinoma (HCC) is the 5th most common cancer worldwide. It is intrinsically resistant toward standard chemotherapy, making it imperative to develop novel selective chemotherapeutic agents. The Wnt/beta-catenin pathway plays critical roles in development and oncogenesis, and is dysregulated in HCC. Our study aims to evaluate the activity of 3 small molecule antagonists of the Tcf4/beta-catenin complex (PKF118-310, PKF115-584 and CGP049090) on HCC cell lines in vitro and in vivo. All 3 chemicals displayed dose-dependent cytotoxicity in vitro against all 3 HCC cell lines (HepG2, Hep40 and Huh7), but were at least 10 times less cytotoxic to normal hepatocytes (from 3 donors) by using ATP assay. In HepG2 and Huh7 cells, treatment with the antagonists decreased Tcf4/beta-catenin binding capability and transcriptional activity, associated with downregulation of the endogenous Tcf4/ beta-catenin target genes c-Myc, cyclin D1 and survivin. In HepG2 and Huh7 cells, treatment with the antagonists induced apoptosis and cell cycle arrest at the G1/S phase. All antagonists suppressed in vivo tumor growth in a HepG2 xenograft model, associated with apoptosis and reduced c-Myc, cyclin D1 and survivin expressions. Our results suggest that these 3 antagonists of the Tcf4/beta-catenin complex are potential chemotherapeutic agents which may offer a pathway specific option for the clinical management of HCC.

    View details for DOI 10.1002/ijc.24810

    View details for Web of Science ID 000276928700016

    View details for PubMedID 19662654

  • Blockade of Wnt-1 signaling leads to anti-tumor effects in hepatocellular carcinoma cells MOLECULAR CANCER Wei, W., Chua, M., Grepper, S., So, S. K. 2009; 8


    Hepatocellular carcinoma (HCC) is an aggressive cancer, and is the third leading cause of cancer death worldwide. Standard therapy is ineffective partly because HCC is intrinsically resistant to conventional chemotherapy. Its poor prognosis and limited treatment options make it critical to develop novel and selective chemotherapeutic agents. Since the Wnt/beta-catenin pathway is essential in HCC carcinogenesis, we studied the inhibition of Wnt-1-mediated signaling as a potential molecular target in HCC.We demonstrated that Wnt-1 is highly expressed in human hepatoma cell lines and a subgroup of human HCC tissues compared to paired adjacent non-tumor tissues. An anti-Wnt-1 antibody dose-dependently decreased viability and proliferation of Huh7 and Hep40 cells over-expressing Wnt-1 and harboring wild type beta-catenin, but did not affect normal hepatocytes with undetectable Wnt-1 expression. Apoptosis was also observed in Huh7 and Hep40 cells after treatment with anti-Wnt-1 antibody. In these two cell lines, the anti-Wnt-1 antibody decreased beta-catenin/Tcf4 transcriptional activities, which were associated with down-regulation of the endogenous beta-catenin/Tcf4 target genes c-Myc, cyclin D1, and survivin. Intratumoral injection of anti-Wnt-1 antibody suppressed in vivo tumor growth in a Huh7 xenograft model, which was also associated with apoptosis and reduced c-Myc, cyclin D1, and survivin expressions.Our results suggest that Wnt-1 is a survival factor for HCC cells, and that the blockade of Wnt-1-mediated signaling may offer a potential pathway-specific therapeutic strategy for the treatment of a subgroup of HCC that over-expresses Wnt-1.

    View details for DOI 10.1186/1476-4598-8-76

    View details for Web of Science ID 000270970900002

    View details for PubMedID 19778454

    View details for PubMedCentralID PMC2759906

  • N-Myc down-regulated gene 1 mediates proliferation, invasion, and apoptosis of hepatocellular carcinoma cells CANCER LETTERS Yan, X., Chua, M., Sun, H., So, S. 2008; 262 (1): 133-142


    The over-expression of N-myc down-regulated gene 1 (NDRG1) in hepatocellular carcinoma (HCC) was previously reported to correlate with vascular invasion and patient survival. Our current study aims to elucidate its functions in HCC. We found that it lacked the tumorigenic ability to promote soft agar colony formation or serum-independent growth of NIH3T3 cells. We used specific small interfering RNA (siRNA) oligos to suppress the expression of NDRG1 in human HCC (Hep3B and HepG2) cell lines, and found that this significantly reduced cell proliferation and invasion, and induced apoptosis. Additionally, NDRG1-specific siRNA inhibited the HepG2 xenograft growth in nude mice. These results are consistent with our earlier clinical observations that NDRG1 is associated with more aggressive tumor behavior, and suggest that NDRG1 may be a potential therapeutic target for HCC.

    View details for DOI 10.1016/j.canlet.2007.12.010

    View details for Web of Science ID 000254683900016

    View details for PubMedID 18207320

  • Small interfering RNA targeting CDC25B inhibits liver tumor growth in vitro and in vivo MOLECULAR CANCER Yan, X., Chua, M., He, J., So, S. K. 2008; 7


    Using gene expression profiling, we previously identified CDC25B to be significantly highly expressed in hepatocellular carcinoma (HCC) compared to non-tumor liver. CDC25B is a cell cycle-activating phosphatase that positively regulates the activity of cyclin-dependent kinases, and is over-expressed in a variety of human malignancies. In this study, we validated the over-expression of CDC25B in HCC, and further investigated its potential as a therapeutic target for the management of HCC.Quantitative real-time polymerase chain reaction and immunohistochemical staining of patient samples confirmed the significant over-expression of CDC25B in HCC compared to non-tumor liver samples (P < 0.001). Thus, intefering with the expression and activity of CDC25B may be a potential way to intervene with HCC progression. We used RNA interference to study the biological effects of silencing CDC25B expression in HCC cell lines (Hep3B and Hep40), in order to validate its potential as a therapeutic target. Using small oligo siRNAs targeting the coding region of CDC25B, we effectively suppressed CDC25B expression by up to 90%. This was associatetd with significant reductions in cell growth rate, cell migration and invasion through the matrigel membrane, and caused significant cell cycle delay at the G2 phase. Finally, suppression of CDC25B significantly slowed the growth of Hep40 xenografts in nude mice.Our data provide evidence that the inhibition of CDC25B expression and activity lead to suppression of tumor cell growth and motility, and may therefore be a feasible approach in the clinical management of HCC.

    View details for DOI 10.1186/1476-4598-7-19

    View details for Web of Science ID 000254456800001

    View details for PubMedID 18269767

    View details for PubMedCentralID PMC2276234

  • Antibody Arrays Identify Potential Diagnostic Markers of Hepatocellular Carcinoma. Biomarker insights Sun, H., Chua, M., Yang, D., Tsalenko, A., Peter, B. J., So, S. 2008; 3: 1-18


    Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide. Effective treatment of HCC patients is hampered by the lack of sensitive and specific diagnostic markers of HCC. Alpha-fetoprotein (AFP), the currently used HCC marker, misses 30%-50% of HCC patients, who therefore remain undiagnosed and untreated. In order to identify novel diagnostic markers that can be used individually or in combination with AFP, we used an antibody array platform to detect the levels of candidate proteins in the plasma of HCC patients (n = 48) and patients with chronic hepatitis B or C viral infections (n = 19) (both of which are the major risk factors of HCC). We identified 7 proteins that significantly differentiate HCC patients from hepatitis patients (p < 0.05) (AFP, CTNNB, CSF1, SELL, IGFBP6, IL6R, and VCAM1). Importantly, we also identified 8 proteins that significantly differentiate HCC patients with 'normal' levels of AFP (< 20 ng/ml) from hepatitis patients (p < 0.05) (IL1RN, IFNG, CDKN1A, RETN, CXCL14, CTNNB, FGF2, and SELL). These markers are potentially important complementary markers to AFP. Using an independent immunoassay method in an independent group of 23 HCC patients and 22 hepatitis patients, we validated that plasma levels of CTNNB were significantly higher in the HCC group (p = 0.020). In conclusion, we used an antibody array platform to identify potential circulating diagnostic markers of HCC, some of which may be valuable when used in combination with AFP. The clinical utility of these newly identified HCC diagnostic markers needs to be systematically evaluated.

    View details for PubMedID 19578489

  • Overexpression of NDRG1 is an indicator of poor prognosis in hepatocellular carcinoma MODERN PATHOLOGY Chua, M., Sun, H., Cheung, S. T., Mason, V., Higgins, J., Ross, D. T., Fan, S. T., So, S. 2007; 20 (1): 76-83


    Hepatocellular carcinoma is a highly lethal cancer that typically has poor prognosis. Prognostic markers can help in its clinical management and in understanding the biology of poor prognosis. Through an earlier gene expression study, we identified N-Myc downregulated gene 1 (NDRG1) to be significantly highly expressed in hepatocellular carcinoma compared to nontumor liver. As NDRG1 is a differentiation-related gene with putative metastasis suppressor activity, we investigated the clinical significance of its overexpression. Quantitative real-time polymerase chain reaction using an independent set of patient samples confirmed the significant overexpression of NDRG1 in hepatocellular carcinoma compared to nontumor liver samples (P<0.001). Additionally, high levels of NDRG1 transcript correlated with shorter overall survival (P<0.001), late tumor stage (P=0.001), vascular invasion (P=0.003), large tumor size (P=0.011), and high Edmondson-Steiner histological grade (P=0.005). Using immunohistochemistry, NDRG1 protein was found to be significantly overexpressed in hepatocellular carcinoma samples compared to nontumor liver or cirrhotic and benign liver lesions (P<0.001). Among the hepatocellular carcinoma samples, those which are moderately and poorly differentiated express higher levels of NDRG1 protein than those which are well-differentiated (P<0.005). Additionally, hepatocellular carcinomas with vascular invasion also express elevated levels of NDRG1 protein compared to those without vascular invasion (significant at P<0.005). Our results suggest NDRG1 to be a likely tumor marker for hepatocellular carcinoma, the overexpression of which is correlated with tumor differentiation, vascular invasion, and overall survival. Its significantly elevated expression in hepatocellular carcinoma could be a useful indicator of tumor aggressiveness and therefore patient prognosis.

    View details for DOI 10.1038/modpathol.3800711

    View details for Web of Science ID 000243005000010

    View details for PubMedID 17170744

  • Sprouty and cancer: the first terms report. Cancer letters Lo, T. L., Fong, C. W., Yusoff, P., McKie, A. B., Chua, M. S., Leung, H. Y., Guy, G. R. 2006; 242 (2): 141-50


    The Ras/Erk signaling pathway has a central role in development of multi-cellular organisms as well as in signal transmission in the mature individual. Recently, a family of genes, designated Sprouty, induced by the Ras/Erk pathway was found to specify proteins that inhibited the upstream pathway. Being in a position that is likely to control well-characterized oncogene products suggested that the expression levels of the Sprouty genes may be relevant in human carcinogenesis. Early data on the deregulation of Sprouty expression in breast, prostate and liver cancers is discussed along with the notion that some of them might have potential as tumour markers or that the derived proteins may act as tumour suppressors.

    View details for DOI 10.1016/j.canlet.2005.12.032

    View details for PubMedID 16469433

  • Gallium maltolate is a promising chemotherapeutic agent for the treatment of hepatocellular carcinoma ANTICANCER RESEARCH Chua, M., Bernstein, L. R., Li, R., So, S. K. 2006; 26 (3A): 1739-1743


    Hepatocellular carcinoma (HCC) is a particularly lethal cancer with few treatment options. Since gallium is known to accumulate specifically in HCC tumors but not in non-tumor liver, we investigated two gallium compounds, gallium nitrate (GaN) and gallium maltolate (GaM), as potential new agents for treating HCC.The anti-proliferative and apoptotic activities of GaN and GaM were assessed in vitro using four HCC cell lines. HCC gene expression data was analyzed to provide a mechanistic rationale for using gallium in the treatment of HCC.Both compounds showed dose-dependent antiproliferative activity in all four HCC cell lines after 6-day drug exposure (IC50 values range from 60-250 microM for gallium nitrate and 25-35 microM for gallium maltolate). Gallium maltolate at 30 microM additionally induced apoptosis after 6 days. HCC gene expression data showed significantly elevated expression of the M2 subunit of ribonucleotide reductase, which is a target for the antiproliferative activity of gallium.These data support clinical testing of gallium maltolate, an orally active compound, in the treatment of HCC.

    View details for Web of Science ID 000238490700002

    View details for PubMedID 16827101

  • Sprouty 2, an inhibitor of mitogen-activated protein kinase signaling, is down-regulated in hepatocellular carcinoma CANCER RESEARCH Fong, C. W., Chua, M. S., McKie, A. B., Ling, S. H., Mason, L., Li, R., Yusoff, P., Lo, T. L., Leung, H. Y., So, S. K., Guy, G. R. 2006; 66 (4): 2048-2058


    The Sprouty proteins are increasingly being recognized to be deregulated in various types of cancers. This deregulation is often associated with aberrant signaling of receptor tyrosine kinases and its downstream effectors, leading to the mitogen-activated protein kinase (MAPK) signaling pathway. In human hepatocellular carcinoma, where the MAPK activity is enhanced via multiple hepatocarcinogenic factors, we observed a consistent reduced expression of the sprouty 2 (Spry2) transcript and protein in malignant hepatocytes compared with normal or cirrhotic hepatocytes. The expression pattern of Spry2 in hepatocellular carcinoma resembles that of several potential tumor markers of hepatocellular carcinoma and also that of several angiogenic factors and growth factor receptors. In contrast to previous studies of Spry2 down-regulation in other cancers, we have ruled out loss of heterozygosity or the methylation of promoter sites, two common mechanisms responsible for the silencing of genes with tumor suppressor properties. Functionally, we show that Spry2 inhibits both extracellular signal-regulated kinase signaling as well as proliferation in hepatocellular carcinoma cell lines, whereas knocking down Spry2 levels in NIH3T3 cells causes mild transformation. Our study clearly indicates a role for Spry2 in hepatocellular carcinoma, and an understanding of the regulatory controls of its expression could provide new means of regulating the angiogenic switch in this hypervascular tumor, thereby potentially controlling tumor growth.

    View details for DOI 10.1158/0008-5472.CAN-05-1072

    View details for Web of Science ID 000235387200024

    View details for PubMedID 16489004

  • An integrated data analysis approach to characterize genes highly expressed in hepatocellular carcinoma ONCOGENE Patil, M. A., Chua, M. S., Pan, K. H., Lin, R., Lih, C. J., Cheung, S. T., Ho, C., Li, R., Fan, S. T., Cohen, S. N., Chen, X., So, S. 2005; 24 (23): 3737-3747


    Hepatocellular carcinoma (HCC) is one of the major causes of cancer deaths worldwide. New diagnostic and therapeutic options are needed for more effective and early detection and treatment of this malignancy. We identified 703 genes that are highly expressed in HCC using DNA microarrays, and further characterized them in order to uncover novel tumor markers, oncogenes, and therapeutic targets for HCC. Using Gene Ontology annotations, genes with functions related to cell proliferation and cell cycle, chromatin, repair, and transcription were found to be significantly enriched in this list of highly expressed genes. We also identified a set of genes that encode secreted (e.g. GPC3, LCN2, and DKK1) or membrane-bound proteins (e.g. GPC3, IGSF1, and PSK-1), which may be attractive candidates for the diagnosis of HCC. A significant enrichment of genes highly expressed in HCC was found on chromosomes 1q, 6p, 8q, and 20q, and we also identified chromosomal clusters of genes highly expressed in HCC. The microarray analyses were validated by RT-PCR and PCR. This approach of integrating other biological information with gene expression in the analysis helps select aberrantly expressed genes in HCC that may be further studied for their diagnostic or therapeutic utility.

    View details for DOI 10.1038/sj.onc.1208479

    View details for Web of Science ID 000229346300005

    View details for PubMedID 15735714

  • Applications of microarrays to renal transplantation: Progress and possibilities FRONTIERS IN BIOSCIENCE-LANDMARK Chua, M. S., Mansfield, E., Sarwal, M. 2003; 8: S913-S923


    By rapidly generating global views of gene expression profiles, microarray technology offers a great advantage over traditional methods of studying gene expression. This technology is gaining rapid and widespread use in many areas of science and medicine because it can be easily adapted to study many experimental questions. This article will review the current applications of microarray technology in the field of renal transplantation, and discuss the potential impact of this technology on transplantation medicine.

    View details for Web of Science ID 000185226700036

    View details for PubMedID 12957854

  • Molecular heterogeneity in acute renal allograft rejection identified by DNA microarray profiling NEW ENGLAND JOURNAL OF MEDICINE Sarwal, M., Chua, M. S., Kambham, N., Hsieh, S. C., Satterwhite, T., Masek, M., Salvatierra, O. 2003; 349 (2): 125-138


    The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment.We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles.We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001).Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection.

    View details for Web of Science ID 000184024400005

    View details for PubMedID 12853585

  • Microarrays: new tools for transplantation research PEDIATRIC NEPHROLOGY Chua, M. S., Sarwal, M. M. 2003; 18 (4): 319-327


    The advent of DNA microarray technology has greatly enhanced our potential to understand the molecular basis of human diseases and to aid in more accurate classification, diagnosis and/or prognosis. This powerful, flexible and highly informative technique has been adopted by many biomedical research disciplines. The use of DNA microarrays for gene expression profiling of patients undergoing organ transplantation has diagnostic and therapeutic potential. By generating global views of the gene expression changes in renal graft function post transplantation, DNA microarray technology will provide important information to improve our understanding of the molecular basis of various causes of graft dysfunction, and therefore suggest improved diagnosis, disease classification, and treatment.

    View details for DOI 10.1007/s00467-003-1083-7

    View details for Web of Science ID 000182761800002

    View details for PubMedID 12700956

  • Increased expression of cytotoxic effector molecules: Different interpretations for steroid-based and steroid-free immunosuppression PEDIATRIC TRANSPLANTATION Satterwhite, T., Chua, M. S., Hsieh, S. C., Chang, S., Scandling, J., Salvatierra, O., Sarwal, M. M. 2003; 7 (1): 53-58


    Cytotoxic T lymphocyte (CTL) effector molecules have been studied as markers of acute rejection in renal allograft recipients on steroid-based immunosuppression. We hypothesized that basal CTL gene expression may vary with time post-transplantation as well as with different immunosuppression protocols (steroid-based or steroid-free). Variations in CTL gene expression may thus impact on the ability to predict acute allograft rejection. We used the non-invasive method of quantitative competitive-reverse transcription-polymerase chain reaction (QC-RT-PCR) to quantify the amounts of CTL effector molecules (granulysin, GL; perforin, P; granzyme B, GB) in serial peripheral blood lymphocyte (PBL) samples from steroid-free and steroid-based adult and pediatric renal allograft recipients. Patients on both protocols were clinically monitored by protocol biopsies at 1, 3, 6, and 12 months post-transplantation and for graft function at 1 yr post-transplantation in a separate clinical study. Steroid-free patients with stable graft function showed an increase in GL, P, and GB gene expression over time post-transplantation with the increase being seen largely by the first post-transplant month. A further increase in GL expression was noted at the end of the first post-transplant year in the absence of acute rejection, whereas GB and P levels were unchanged. At comparative time-points post-transplantation, CTL genes were found to be higher in steroid-free patients with stable graft function, compared to steroid-based recipients with either clinically stable graft function or acute rejection. This study suggests that levels of CTL gene expression, although important in a steroid-based regimen to monitor the risk of acute rejection, may not be similarly applied in patients on steroid-free immunosuppression. The early increase in levels seen in steroid-free patients appears to correlate with the total absence of steroids. As steroid-free patients seem to have a lower incidence of acute rejection and better long-term graft function at 1 yr, the early increase in CTL genes in the absence of acute rejection may suggest an early adaptive immune activation response, promoting early graft acceptance in this protocol.

    View details for Web of Science ID 000180971500011

    View details for PubMedID 12581329

  • Molecular profiling of anemia in acute renal allograft rejection using DNA microarrays AMERICAN JOURNAL OF TRANSPLANTATION Chua, M. S., Barry, C., Chen, X., Salvatierra, O., Sarwal, M. M. 2003; 3 (1): 17-22


    Compromised renal function after renal allograft transplantation often results in anemia in the recipient. Molecular mechanisms leading to anemia during acute rejection are not fully understood; inadequate erythropoietin production and iron deficiency have been reported to be the main contributors. To increase our understanding of the molecular events underlying anemia in acute rejection, we analyzed the gene expression profiles of peripheral blood lymphocytes (PBL) from four pediatric renal allograft recipients with acute rejection and concurrent anemia, using DNA microarrays containing 9000 human cDNA clones (representing 7469 unique genes). In these anemic rejecting patients, an 'erythropoiesis cluster' of 11 down-regulated genes was identified, involved in hemoglobin transcription and synthesis, iron and folate binding and transport. Additionally, some alloimmune response genes were simultaneously down-regulated. An independent data set of 36 PBL samples, some with acute rejection and some with concurrence of acute rejection and anemia, were analyzed to support a possible association between acute rejection and anemia. In conclusion, analysis using DNA microarrays has identified a cluster of genes related to hemoglobin synthesis and/or erythropoeisis that was altered in kidneys with renal allograft rejection compared with normal kidneys. The possible relationship between alterations in the expression of this cluster, reduced renal function, the alloimmune process itself, and other influences on the renal transplant awaits further analysis.

    View details for Web of Science ID 000180225200004

    View details for PubMedID 12492705

  • In vitro evaluation of amino acid prodrugs of novel antitumour 2-(4-amino-3-methylphenyl)benzothiazoles. British journal of cancer Bradshaw, T. D., Chua, M. S., Browne, H. L., Trapani, V., Sausville, E. A., Stevens, M. F. 2002; 86 (8): 1348-54


    Novel 2-(4-aminophenyl)benzothiazoles possess highly selective, potent antitumour properties in vitro and in vivo. They induce and are biotransformed by cytochrome P450 (CYP) 1A1 to putative active as well as inactive metabolites. Metabolic inactivation of the molecule has been thwarted by isosteric replacement of hydrogen with fluorine atoms at positions around the benzothiazole nucleus. The lipophilicity of these compounds presents limitations for drug formulation and bioavailability. To overcome this problem, water soluble prodrugs have been synthesised by conjugation of alanyl- and lysyl-amide hydrochloride salts to the exocyclic primary amine function of 2-(4-aminophenyl)benzothiazoles. The prodrugs retain selectivity with significant in vitro growth inhibitory potency against the same sensitive cell lines as their parent amine, but are inactive against cell lines inherently resistant to 2-(4-aminophenyl)benzothiazoles. Alanyl and lysyl prodrugs rapidly and quantitatively revert to their parent amine in sensitive and insensitive cell lines in vitro. Liberated parent compounds are sequestered and metabolised by sensitive cells only; similarly, CYP1A1 activity and protein expression are selectively induced in sensitive carcinoma cells. Amino acid prodrugs meet the criteria of aqueous solubility, chemical stability and quantitative reversion to parent molecule, and thus are suitable for in vivo preclinical evaluation.

    View details for DOI 10.1038/sj.bjc.6600225

    View details for PubMedID 11953897

    View details for PubMedCentralID PMC2375326

  • Antitumor benzothiazoles. 14. Synthesis and in vitro biological properties of fluorinated 2-(4-aminophenyl)benzothiazoles. Journal of medicinal chemistry Hutchinson, I., Chua, M. S., Browne, H. L., Trapani, V., Bradshaw, T. D., Westwell, A. D., Stevens, M. F. 2001; 44 (9): 1446-55


    Synthetic routes to a series of mono- and difluorinated 2-(4-amino-3-substituted-phenyl)benzothiazoles have been devised. Whereas mixtures of regioisomeric 5- and 7-fluoro-benzothiazoles were formed from the established Jacobsen cyclization of precursor 3-fluoro-thiobenzanilides, two modifications to this general process have allowed the synthesis of pure samples of these target compounds. Fluorinated 2-(4-aminophenyl)benzothiazoles were potently cytotoxic (GI(50) < 1 nM) in vitro in sensitive human breast MCF-7 (ER+) and MDA 468 (ER-) cell lines but inactive (GI(50) > 10 microM) against PC 3 prostate, nonmalignant HBL 100 breast, and HCT 116 colon cells. The biphasic dose-response relationship characteristically shown by the benzothiazole series against sensitive cell lines was exhibited by the 4- and 6-fluoro-benzothiazoles (10b,d) but not by the 5- and 7-fluoro-benzothiazoles (10h,i). The most potent broad spectrum agent in the NCI cell panel was 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (10h) which, unlike the 6-fluoro isomer (10d), produces no exportable metabolites in the presence of sensitive MCF-7 cells. Induction of cytochrome P450 CYP1A1, a crucial event in determining the antitumor specificity of this series of benzothiazoles, was not compromised. 10h is currently the focus of pharmaceutical and preclinical development.

    View details for DOI 10.1021/jm001104n

    View details for PubMedID 11311068

  • Antitumour benzothiazoles. Part 15: The synthesis and physico-chemical properties of 2-(4-aminophenyl)benzothiazole sulfamate salt derivatives. Bioorganic & medicinal chemistry letters Shi, D. F., Bradshaw, T. D., Chua, M. S., Westwell, A. D., Stevens, M. F. 2001; 11 (8): 1093-5


    A series of sulfamate salt derivatives of the potent and selective 2-(4-aminophenyl)benzothiazole antitumour agents has been prepared and their evaluation as potential prodrugs for parenteral administration carried out. The salts were sparingly soluble under aqueous conditions (pH 4-9), and degradation to the active free amine was shown to occur under strongly acidic conditions. The salts were found to be markedly less active than their parent amines against sensitive human tumour cell lines in vitro.

    View details for DOI 10.1016/s0960-894x(01)00142-1

    View details for PubMedID 11327598

  • Role of Cyp1A1 in modulation of antitumor properties of the novel agent 2-(4-amino-3-methylphenyl)benzothiazole (DF 203, NSC 674495) in human breast cancer cells. Cancer research Chua, M. S., Kashiyama, E., Bradshaw, T. D., Stinson, S. F., Brantley, E., Sausville, E. A., Stevens, M. F. 2000; 60 (18): 5196-203


    2-(4-Amino-3-methylphenyl)benzothiazole (DF 203, NSC 674495) is a candidate antitumor agent with potent and selective activity against human-derived tumor cell lines in vitro and in vivo. Only sensitive cell lines (e.g., MCF-7) were able to accumulate and metabolize DF 203, forming the main inactive metabolite, 2-(4-amino-3-methylphenyl)-6-hydroxybenzothiazole (6-OH 203). Selective metabolism may therefore underlie its antitumor profile. DF 203 6-hydroxylase activity by MCF-7 cells was not constitutive but induced only after pretreatment of cells with DF 203, 3-methylcholanthrene, or beta-naphthoflavone. 6-Hydroxylation was strongly inhibited by either goat antirat cytochrome P450 1A1 (CYP1A1) serum or alpha-naphthoflavone. Both alpha-naphthoflavone and 6-OH 203 abrogated DF 203-induced growth inhibition. Microsomes from genetically engineered human B-lymphoblastoid cells expressing CYP1A1, CYP1B1, or CYP2D6 metabolized DF 203 to 6-OH 203. Immunoblot analysis detected significantly enhanced CYP1A1 protein in a panel of sensitive breast cancer cell lines after exposure to DF 203. Neither constitutive expression nor induction of CYP1A1 protein was detected in nonresponsive breast (HBL 100, MDA-MB-435, and MCF-7/ADR) and prostate (PC 3 and DU 145) cancer cell lines. The expression of CYP1B1 was also modulated by DF 203 in the same sensitive cell lines. However, of the two isoforms, only CYP1A1 activity was irreversibly inhibited by DF 203 and significantly inhibited by 6-OH 203. In sensitive cell lines only, [14C]DF 203-derived radioactivity bound covalently to a Mr 50,000, protein which was immunoprecipitated by CYP1A1 antiserum. The covalent binding of [14C]DF 203 to recombinant CYP1A1 enzyme was NADPH-dependent and reduced by 6-OH 203 and glutathione. CYP1A1 appears essential for the metabolism of DF 203 and may have a pivotal, yet undefined, role in its antitumor activity.

    View details for PubMedID 11016648

  • Mechanisms of acquired resistance to 2-(4-aminophenyl)benzothiazole (CJM 126, NSC 34445). British journal of cancer Bradshaw, T. D., Chua, M. S., Orr, S., Matthews, C. S., Stevens, M. F. 2000; 83 (2): 270-7


    2-(4-aminophenyl)benzothiazole (CJM 126) elicits potent growth inhibition in human-derived breast carcinoma cell lines, including oestrogen receptor-positive (ER+) MCF-7wt cells. Analogues substituted in the 3' position with I (DF 129), CH3 (DF 203), or Cl (DF 229) possess an extended profile of antitumour activity with remarkable selective activity in cell lines derived from solid tumours associated with poor prognosis, e.g. breast, ovarian, renal and colon. Growth inhibition occurs via unknown, possibly novel mechanism(s) of action. Two cell lines have been derived from sensitive MCF-7wt breast cancer cells (IC50 value < 0.001 microM) following long-term exposure to 10 nM or 10 microM CJM 126, MCF-7(10 nM 126) and MCF-7(10 microM 126) respectively, which demonstrate acquired resistance to this agent (IC50 > 30 microM) and cross-resistance to DF 129, DF 203 and DF 229. Sensitivity to tamoxifen, benzo[a]pyrene (BP), mitomyin C, doxorubicin and actinomycin D is retained. Resistance may, in part, be conferred by the constitutively increased expression of bcl-2 and p53 proteins detected in MCF-7(10 nM 126) and MCF-7(10 microM 126 lysates. Significantly decreased depletion of CJM 126 (30 microM) from nutrient medium of MCF-7(10 microM 126) cells was observed with predominantly cytoplasmic drug localization and negligible DNA strand breaks. N-acetyl transferase (NAT)1 and NAT2 proteins were expressed by all three MCF-7 sub-lines, but significantly higher expression of NAT2 was accompanied by enhanced acetylation efficacy in MCF-7(10 nM 126) cells. In contrast, CJM 126 (30 microM) was rapidly depleted from nutrient medium of MCF-7(10 microM 126) culture and accessed nuclei of these cells exerting damage to DNA. The major biotransformation product of CJM 126 in MCF-7(10 microM 126) cells was 2-(4-aminophenyl)-6-hydroxybenzothiazole (6-OH 126). This metabolite possessed no antitumour activity. Accordingly, in this sub-line, low constitutive expression and activity of cytochrome P450 (CYP) 1A1 was detected.

    View details for DOI 10.1054/bjoc.2000.1231

    View details for PubMedID 10901382

    View details for PubMedCentralID PMC2363474

  • Antitumor benzothiazoles. 8. Synthesis, metabolic formation, and biological properties of the C- and N-oxidation products of antitumor 2-(4-aminophenyl)benzothiazoles. Journal of medicinal chemistry Kashiyama, E., Hutchinson, I., Chua, M. S., Stinson, S. F., Phillips, L. R., Kaur, G., Sausville, E. A., Bradshaw, T. D., Westwell, A. D., Stevens, M. F. 1999; 42 (20): 4172-84


    2-(4-Aminophenyl)benzothiazoles 1 and their N-acetylated forms have been converted to C- and N-hydroxylated derivatives to investigate the role of metabolic oxidation in the mode of action of this series of compounds. 2-(4-Amino-3-methylphenyl)benzothiazole (1a, DF 203, NSC 674495) is a novel and potent antitumor agent with selective growth inhibitory properties against human cancer cell lines. Very low IC(50) values (<0.1 microM) were encountered in the most sensitive breast cancer cell lines, MCF-7 and T-47D, whereas renal cell line TK-10 was weakly inhibited by 1a. Cell lines from the same tissue origin, MDA-MB-435 (breast), CAKI-1 (renal), and A498 (renal), were insensitive to 1a. Accumulation and metabolism of 1a were observed in sensitive cell lines only, with the highest rate of metabolism occurring in the most sensitive MCF-7 and T-47D cells. Thus, differential uptake and metabolism of 1a by cancer cell lines may underlie its selective profile of anticancer activity. A major metabolite in these sensitive cell lines has been identified as 2-(4-amino-3-methylphenyl)-6-hydroxybenzothiazole (6c). Hydroxylation of 1a was not detected in the homogenate of previously untreated MCF-7, T-47D, and TK-10 cells but was readily observed in homogenates of sensitive cells that were pretreated with 1a. Accumulation and covalent binding of [(14)C]1a derived radioactivity was observed in the sensitive MCF-7 cell line but not in the insensitive MDA-MB-435 cell line. The mechanism of growth inhibition by 1a, which is unknown, may be dependent on the differential metabolism of the drug to an activated form by sensitive cell lines only and its covalent binding to an intracellular protein. However, the 6-hydroxy derivative 6c is not the 'active' metabolite since, like all other C- and N-hydroxylated benzothiazoles examined in this study, it is devoid of antitumor properties in vitro.

    View details for DOI 10.1021/jm990104o

    View details for PubMedID 10514287

  • Antitumor benzothiazoles. 7. Synthesis of 2-(4-acylaminophenyl)benzothiazoles and investigations into the role of acetylation in the antitumor activities of the parent amines. Journal of medicinal chemistry Chua, M. S., Shi, D. F., Wrigley, S., Bradshaw, T. D., Hutchinson, I., Shaw, P. N., Barrett, D. A., Stanley, L. A., Stevens, M. F. 1999; 42 (3): 381-92


    2-(4-Aminophenyl)benzothiazoles display potent and selective antitumor activity against inter alia breast, ovarian, colon, and renal cell lines, but their mechanism of action, though yet to be defined, may be novel. Metabolism is suspected to play a central role in the mode of action of these benzothiazoles since drug uptake and biotransformation were observed in sensitive cell lines (e.g., breast MCF-7 and MDA 468 cells) in vitro, whereas insensitive cell lines (e.g., prostate PC 3 cells) showed negligible uptake and biotransformation. N-Acyl derivatives of the arylamines have been synthesized, and in vitro studies confirm N-acetylation and oxidation as the main metabolic transformations of 2-(4-aminophenyl)benzothiazoles, with the predominant process being dictated by the nature of the 3'-substituent. The prototype amine 3 underwent mainly N-acetylation in vitro, while 3'-substituted analogues 4 and 5 were primarily oxidized. N-Acetylation of 4 to 11 exerts a drastic dyschemotherapeutic effect in vitro, but acetylation of the halogeno congeners 5-7 gave acetylamines 12-14 which substantially retain selective antitumor activity. In vivo pharmacokinetic studies in rats confirmed rapid and exclusive N-acetylation of the 3'-methyl analogue 4, but less acetylation with the 3'-chloro analogue 5. Distinct expression patterns of N-acetyltransferase NAT1 and NAT2 have been demonstrated in our panel of cell lines.

    View details for DOI 10.1021/jm981076x

    View details for PubMedID 9986708