All Publications

  • Longitudinal assessment of ultrasound-guided complementary microRNA therapy of hepatocellular carcinoma. Journal of controlled release : official journal of the Controlled Release Society Chowdhury, S. M., Lee, T., Bachawal, S. V., Devulapally, R., Abou-Elkacem, L., Yeung, T. A., Wischhusen, J., Tian, L., Dahl, J., Paulmurugan, R., Willmann, J. K. 2018


    Hepatocellular carcinoma (HCC) is the second-leading cause of cancer related deaths worldwide and new strategies to efficiently treat HCC are critically needed. The aim of this study was to assess the longitudinal treatment effects of two complementary miRNAs (miRNA-122 and antimiR-21) encapsulated in biodegradable poly lactic-co-glycolic acid (PLGA) - poly ethylene glycol (PEG) nanoparticles (PLGA-PEG-NPs), administered by an ultrasound-guided and microbubble-mediated delivery approach in doxorubicin-resistant and non-resistant human HCC xenografts. Using in vitro assays, we show that repeated miRNA treatments resulted in gradual reduction of HCC cell proliferation and reversal of doxorubicin resistance. Optimized US parameters resulted in a 9-16 fold increase (p = 0.03) in miRNA delivery in vivo in HCC tumors after two US treatments compared to tumors without US treatment. Furthermore, when combined with doxorubicin (10 mg/kg), longitudinal miRNA delivery showed a significant inhibition of tumor growth in both resistant and non-resistant tumors compared to non-treated, and doxorubicin treated controls. We also found that ultrasound-guided miRNA therapy was not only effective in inhibiting HCC tumor growth but also allowed lowering the dose of doxorubicin needed to induce apoptosis. In conclusion, the results of this study suggest that ultrasound-guided and MB-mediated delivery of miRNA-122 and antimiR-21, when combined with doxorubicin, is a highly effective approach to treat resistant HCC while reducing doxorubicin doses needed for treating non-resistant HCC in longitudinal treatment experiments. Further refinement of this strategy could potentially lead to better treatment outcomes for patients with HCC.

    View details for DOI 10.1016/j.jconrel.2018.05.009

    View details for PubMedID 29758233

  • Ultrasound-guided delivery of thymidine kinase-nitroreductase dual therapeutic genes by PEGylated-PLGA/PIE nanoparticles for enhanced triple negative breast cancer therapy. Nanomedicine (London, England) Devulapally, R., Lee, T., Barghava-Shah, A., Sekar, T. V., Foygel, K., Bachawal, S. V., Willmann, J. K., Paulmurugan, R. 2018; 13 (9): 1051–66


    AIM: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype. Since no targeted therapy is available, gene-directed enzyme prodrug therapy (GDEPT) could be an attractive strategy for treating TNBC.MATERIALS & METHODS: Polyethylene glycol (PEG)ylated-poly(lactic-co-glycolic acid)/polyethyleneimine nanoparticles (PLGA/PEI NPs) were synthesized and complexed with TK-NTR fusion gene. Ultrasound (US)and microbubble (MB) mediated sonoporation was used for efficient delivery of the TK-NTR-DNA-NP complex to TNBC tumor in vivo for cancer therapy. Therapeutic effect was evaluated by treating TNBC cells in vitro and tumor xenograft in vivo by using prodrugs ganciclovir (GCV) and CB1954.RESULTS: TNBC cells treated with GCV/CB1954 prodrugs after transfection of TK-NTR-DNA by PEGylated-PLGA/PEI NP resulted in high apoptotic-index. US-MB image-guided delivery of TK-NTR-DNA-NP complex displayed significant expression level of TK-NTR protein and showed tumor reduction when treated with GCV/CB1954 prodrugs in TNBC xenograft in vivo.CONCLUSION: US-MB image-guided delivery of TK-NTR gene by PEGylated-PLGA/PEI NPs could be a potential prodrug therapy for TNBC in the clinic.

    View details for DOI 10.2217/nnm-2017-0328

    View details for PubMedID 29790803

  • Thy1-Targeted Microbubbles for Ultrasound Molecular Imaging of Pancreatic Ductal Adenocarcinoma. Clinical cancer research : an official journal of the American Association for Cancer Research Abou-Elkacem, L., Wang, H., Chowdhury, S. M., Kimura, R. H., Bachawal, S. V., Gambhir, S. S., Tian, L., Willmann, J. K. 2018


    To engineer a dual human and murine Thy1-binding single-chain-antibody ligand (Thy1-scFv) for contrast microbubble-enhanced ultrasound molecular imaging of pancreatic ductal adenocarcinoma (PDAC). Thy1-scFv were engineered using yeast-surface-display techniques. Binding to soluble human and murine Thy1 and to Thy1-expressing cells was assessed by flow cytometry. Thy1-scFv was then attached to gas-filled microbubbles to create MB Thy1-scFv. Thy1 binding of MB Thy1-scFv to Thy1-expressing cells was evaluated under flow shear stress conditions in flow-chamber experiments. MB scFv-scrambled and MB Non-targeted were used as negative controls. All microbubble types were tested in both orthotopic human PDAC xenografts and transgenic PDAC mice in vivo. Results: Thy1-scFv had a K D of 3.4±0.36 nM for human and 9.2±1.7 nM for murine Thy1 and showed binding to both soluble and cellularly expressed Thy1. MB Thy1-scFv attached to Thy1 with high affinity compared to negative control microbubbles P<0.01) as assessed by flow cytometry. Similarly, flow-chamber studies showed significantly (P<0.01) higher binding of MB Thy1-scFv (3.0±0.81 MB/cell) to Thy1-expressing cells than MB scFv-scrambled (0.57±0.53) and MB Non-targeted (0.43±0.53). In vivo ultrasound molecular imaging using MB Thy1-scFv demonstrated significantly higher signal (P<0.01) in both orthotopic (5.32±1.59 a.u.) and transgenic PDAC (5.68±2.5 a.u.) mice compared to chronic pancreatitis (0.84±0.6 a.u.) and normal pancreas (0.67±0.71 a.u.). Ex vivo immunofluorescence confirmed significantly (P<0.01) increased Thy1 expression in PDAC compared to chronic pancreatitis and normal pancreas tissue. Conclusions: A dual human and murine Thy1-binding scFv was designed to generate contrast microbubbles to allow PDAC detection with ultrasound.

    View details for DOI 10.1158/1078-0432.CCR-17-2057

    View details for PubMedID 29301827

  • Spectroscopic Photoacoustic Molecular Imaging of Breast Cancer using a B7-H3-targeted ICG Contrast Agent THERANOSTICS Wilson, K. E., Bachawal, S. V., Abou-Elkacem, L., Jensen, K., Machtaler, S., Tian, L., Willmann, J. K. 2017; 7 (6): 1463-1476


    Purpose: Breast cancer imaging methods lack diagnostic accuracy, in particular for patients with dense breast tissue, and improved techniques are critically needed. The purpose of this study was to evaluate antibody-indocyanine green (ICG) conjugates, which undergo dynamic absorption spectrum shifts after cellular endocytosis and degradation, and spectroscopic photoacoustic (sPA) imaging to differentiate normal breast tissue from breast cancer by imaging B7-H3, a novel breast cancer associated molecular target. Methods: Quantitative immunohistochemical staining of endothelial and epithelial B7-H3 expression was assessed in 279 human breast tissue samples, including normal (n=53), benign lesions (11 subtypes, n=129), and breast cancers (4 subtypes, n=97). After absorption spectra of intracellular and degraded B7-H3-ICG and Isotype control-ICG (Iso-ICG) were characterized, sPA imaging in a transgenic murine breast cancer model (FVB/N-Tg(MMTVPyMT)634Mul) was performed and compared to imaging of control conditions [B7-H3-ICG in tumor negative animals (n=60), Iso-ICG (n=30), blocking B7-H3+B7-H3-ICG (n=20), and free ICG (n=20)] and validated with ex vivo histological analysis. Results: Immunostaining showed differential B7-H3 expression on both the endothelium and tumor epithelium in human breast cancer with an area under the ROC curve of 0.93 to differentiate breast cancer vs non-cancer. Combined in vitro/in vivo imaging showed that sPA allowed specific B7-H3-ICG detection down to the 13 nM concentration and differentiation from Iso-ICG. sPA molecular imaging of B7-H3-ICG showed a 3.01-fold (P<0.01) increase in molecular B7-H3-ICG signal in tumors compared to control conditions. Conclusions: B7-H3 is a promising target for both vascular and epithelial sPA imaging of breast cancer. Leveraging antibody-ICG contrast agents and their dynamic optical absorption spectra allows for highly specific sPA imaging of breast cancer.

    View details for DOI 10.7150/thno.18217

    View details for Web of Science ID 000398783200005

    View details for PubMedID 28529630

  • Quantitative Three-Dimensional Dynamic Contrast-Enhanced Ultrasound Imaging: First-In-Human Pilot Study in Patients with Liver Metastases THERANOSTICS El Kaffas, A., Sigrist, R., Fisher, G., Bachawal, S., Liau, J., Wang, H., Karanany, A., Durot, I., Rosenberg, J., Hristov, D., Willmann, J. K. 2017; 7 (15): 3745–58


    Purpose: To perform a clinical assessment of quantitative three-dimensional (3D) dynamic contrast-enhanced ultrasound (DCE-US) feasibility and repeatability in patients with liver metastasis, and to evaluate the extent of quantitative perfusion parameter sampling errors in 2D compared to 3D DCE-US imaging. Materials and Methods: Twenty consecutive 3D DCE-US scans of liver metastases were performed in 11 patients (45% women; mean age, 54.5 years; range, 48-60 years; 55% men; mean age, 57.6 years; range, 47-68 years). Pairs of repeated disruption-replenishment and bolus DCE-US images were acquired to determine repeatability of parameters. Disruption-replenishment was carried out by infusing 0.9 mL of microbubbles (Definity; Latheus Medical Imaging) diluted in 35.1 mL of saline over 8 min. Bolus consisted of intravenous injection of 0.2 mL microbubbles. Volumes-of-interest (VOI) and regions-or-interest (ROI) were segmented by two different readers in images to extract 3D and 2D perfusion parameters, respectively. Disruption-replenishment parameters were: relative blood volume (rBV), relative blood flow (rBF). Bolus parameters included: time-to-peak (TP), peak enhancement (PE), area-under-the-curve (AUC), and mean-transit-time (MTT). Results: Clinical feasibility and repeatability of 3D DCE-US using both the destruction-replenishment and bolus technique was demonstrated. The repeatability of 3D measurements between pairs of repeated acquisitions was assessed with the concordance correlation coefficient (CCC), and found to be excellent for all parameters (CCC > 0.80), except for the TP (0.74) and MTT (0.30) parameters. The CCC between readers was found to be excellent (CCC > 0.80) for all parameters except for TP (0.71) and MTT (0.52). There was a large Coefficient of Variation (COV) in intra-tumor measurements for 2D parameters (0.18-0.52). Same-tumor measurements made in 3D were significantly different (P = 0.001) than measurements made in 2D; a percent difference of up to 86% was observed between measurements made in 2D compared to 3D in the same tumor. Conclusions: 3D DCE-US imaging of liver metastases with a matrix array transducer is feasible and repeatable in the clinic. Results support 3D instead of 2D DCE US imaging to minimize sampling errors due to tumor heterogeneity.

    View details for DOI 10.7150/thno.20329

    View details for Web of Science ID 000408444200010

    View details for PubMedID 29109773

    View details for PubMedCentralID PMC5667345

  • Ultrasound-guided therapeutic modulation of hepatocellular carcinoma using complementary microRNAs. Journal of controlled release Mullick Chowdhury, S., Wang, T., Bachawal, S., Devulapally, R., Choe, J. W., Abou Elkacem, L., Yakub, B. K., Wang, D. S., Tian, L., Paulmurugan, R., Willmann, J. K. 2016; 238: 272-280


    Treatment options for patients with hepatocellular carcinoma (HCC) are limited, in particular in advanced and drug resistant HCC. MicroRNAs (miRNA) are non-coding small RNAs that are emerging as novel drugs for the treatment of cancer. The aim of this study was to assess treatment effects of two complementary miRNAs (sense miRNA-122, and antisense antimiR-21) encapsulated in biodegradable poly (lactic-co-glycolic acid) nanoparticles (PLGA-NP), administered by an ultrasound-guided and microbubble-enhanced delivery approach in doxorubicin-resistant and non-resistant human HCC xenografts. Proliferation and invasiveness of human HCC cells after miRNA-122/antimiR-21 and doxorubicin treatment were assessed in vitro. Confocal microscopy and qRT-PCR were used to visualize and quantitate successful intracellular miRNA-loaded PLGA-NP delivery. Up and down-regulation of miRNA downstream targets and multidrug resistance proteins and extent of apoptosis were assessed in vivo in treated human HCC xenografts in mice. Compared to single miRNA therapy, combination therapy with the two complementary miRNAs resulted in significantly (P<0.05) stronger decrease in cell proliferation, invasion, and migration of HCC cells as well as higher resensitization to doxorubicin. Ultrasound-guided delivery significantly increased in vivo miRNA-loaded PLGA-NP delivery in human HCC xenografts compared to control conditions by 5-9 fold (P<0.001). miRNA-loaded PLGA-NP were internalized in HCC cells and anti-apoptotic proteins were down regulated with apoptosis in ~27% of the tumor volume of doxorubicin-resistant human HCC after a single treatment with complementary miRNAs and doxorubicin. Thus, ultrasound-guided delivery of complementary miRNAs is highly efficient in the treatment of doxorubicin- resistant and non-resistant HCC. Further development of this new treatment approach could aid in better treatment of patients with HCC.

    View details for DOI 10.1016/j.jconrel.2016.08.005

    View details for PubMedID 27503707

    View details for PubMedCentralID PMC5185600

  • Ultrasound Molecular Imaging of the Breast Cancer Neovasculature using Engineered Fibronectin Scaffold Ligands: A Novel Class of Targeted Contrast Ultrasound Agent. Theranostics Abou-Elkacem, L., Wilson, K. E., Johnson, S. M., Chowdhury, S. M., Bachawal, S., Hackel, B. J., Tian, L., Willmann, J. K. 2016; 6 (11): 1740-1752


    Molecularly-targeted microbubbles (MBs) are increasingly being recognized as promising contrast agents for oncological molecular imaging with ultrasound. With the detection and validation of new molecular imaging targets, novel binding ligands are needed that bind to molecular imaging targets with high affinity and specificity. In this study we assessed a novel class of potentially clinically translatable MBs using an engineered 10(th) type III domain of human-fibronectin (MB-FN3VEGFR2) scaffold-ligand to image VEGFR2 on the neovasculature of cancer. The in vitro binding of MB-FN3VEGFR2 to a soluble VEGFR2 was assessed by flow-cytometry (FACS) and binding to VEGFR2-expressing cells was assessed by flow-chamber cell attachment studies under flow shear stress conditions. In vivo binding of MB-FN3VEGFR2 was tested in a transgenic mouse model (FVB/N Tg(MMTV/PyMT634Mul) of breast cancer and control litter mates with normal mammary glands. In vitro FACS and flow-chamber cell attachment studies showed significantly (P<0.01) higher binding to VEGFR2 using MB-FN3VEGFR2 than control agents. In vivo ultrasound molecular imaging (USMI) studies using MB-FN3VEGFR2 demonstrated specific binding to VEGFR2 and was significantly higher (P<0.01) in breast cancer compared to normal breast tissue. Ex vivo immunofluorescence-analysis showed significantly (P<0.01) increased VEGFR2-expression in breast cancer compared to normal mammary tissue. Our results suggest that MBs coupled to FN3-scaffolds can be designed and used for USMI of breast cancer neoangiogenesis. Due to their small size, stability, solubility, the lack of glycosylation and disulfide bonds, FN3-scaffolds can be recombinantly produced with the advantage of generating small, high affinity ligands in a cost efficient way for USMI.

    View details for DOI 10.7150/thno.15169

    View details for PubMedID 27570547

    View details for PubMedCentralID PMC4997233

  • Ultrasound molecular imaging: Moving toward clinical translation. European journal of radiology Abou-Elkacem, L., Bachawal, S. V., Willmann, J. K. 2015; 84 (9): 1685-1693


    Ultrasound is a widely available, cost-effective, real-time, non-invasive and safe imaging modality widely used in the clinic for anatomical and functional imaging. With the introduction of novel molecularly-targeted ultrasound contrast agents, another dimension of ultrasound has become a reality: diagnosing and monitoring pathological processes at the molecular level. Most commonly used ultrasound molecular imaging contrast agents are micron sized, gas-containing microbubbles functionalized to recognize and attach to molecules expressed on inflamed or angiogenic vascular endothelial cells. There are several potential clinical applications currently being explored including earlier detection, molecular profiling, and monitoring of cancer, as well as visualization of ischemic memory in transient myocardial ischemia, monitoring of disease activity in inflammatory bowel disease, and assessment of arteriosclerosis. Recently, a first clinical grade ultrasound contrast agent (BR55), targeted at a molecule expressed in neoangiogenesis (vascular endothelial growth factor receptor type 2; VEGFR2) has been introduced and safety and feasibility of VEGFR2-targeted ultrasound imaging is being explored in first inhuman clinical trials in various cancer types. This review describes the design of ultrasound molecular imaging contrast agents, imaging techniques, and potential future clinical applications of ultrasound molecular imaging.

    View details for DOI 10.1016/j.ejrad.2015.03.016

    View details for PubMedID 25851932

  • Ultrasound molecular imaging: Moving toward clinical translation EUROPEAN JOURNAL OF RADIOLOGY Abou-Elkacem, L., Bachawal, S. V., Willmann, J. K. 2015; 84 (9): 1685-1693
  • Breast Cancer Detection by B7-H3-Targeted Ultrasound Molecular Imaging. Cancer research Bachawal, S. V., Jensen, K. C., Wilson, K. E., Tian, L., Lutz, A. M., Willmann, J. K. 2015; 75 (12): 2501-2509


    Ultrasound complements mammography as an imaging modality for breast cancer detection, especially in patients with dense breast tissue, but its utility is limited by low diagnostic accuracy. One emerging molecular tool to address this limitation involves contrast-enhanced ultrasound using microbubbles targeted to molecular signatures on tumor neovasculature. In this study, we illustrate how tumor vascular expression of B7-H3 (CD276), a member of the B7 family of ligands for T-cell coregulatory receptors, can be incorporated into an ultrasound method that can distinguish normal, benign, precursor, and malignant breast pathologies for diagnostic purposes. Through an IHC analysis of 248 human breast specimens, we found that vascular expression of B7-H3 was selectively and significantly higher in breast cancer tissues. B7-H3 immunostaining on blood vessels distinguished benign/precursors from malignant lesions with high diagnostic accuracy in human specimens. In a transgenic mouse model of cancer, the B7-H3-targeted ultrasound imaging signal was increased significantly in breast cancer tissues and highly correlated with ex vivo expression levels of B7-H3 on quantitative immunofluorescence. Our findings offer a preclinical proof of concept for the use of B7-H3-targeted ultrasound molecular imaging as a tool to improve the diagnostic accuracy of breast cancer detection in patients. Cancer Res; 75(12); 2501-9. ©2015 AACR.

    View details for DOI 10.1158/0008-5472.CAN-14-3361

    View details for PubMedID 25899053

    View details for PubMedCentralID PMC4470725

  • Ultrasound-guided delivery of microRNA loaded nanoparticles into cancer JOURNAL OF CONTROLLED RELEASE Wang, T., Choe, J. W., Pu, K., Devulapally, R., Bachawal, S., Machtaler, S., Chowdhury, S. M., Luong, R., Tian, L., Khuri-Yakub, B., Rao, J., Paulmurugan, R., Willmann, J. K. 2015; 203: 99-108


    Ultrasound induced microbubble cavitation can cause enhanced permeability across natural barriers of tumors such as vessel walls or cellular membranes, allowing for enhanced therapeutic delivery into the target tissues. While enhanced delivery of small (<1nm) molecules has been shown at acoustic pressures below 1MPa both in vitro and in vivo, the delivery efficiency of larger (>100nm) therapeutic carriers into cancer remains unclear and may require a higher pressure for sufficient delivery. Enhanced delivery of larger therapeutic carriers such as FDA approved pegylated poly(lactic-co-glycolic acid) nanoparticles (PLGA-PEG-NP) has significant clinical value because these nanoparticles have been shown to protect encapsulated drugs from degradation in the blood circulation and allow for slow and prolonged release of encapsulated drugs at the target location. In this study, various acoustic parameters were investigated to facilitate the successful delivery of two nanocarriers, a fluorescent semiconducting polymer model drug nanoparticle as well as PLGA-PEG-NP into human colon cancer xenografts in mice. We first measured the cavitation dose produced by various acoustic parameters (pressure, pulse length, and pulse repetition frequency) and microbubble concentration in a tissue mimicking phantom. Next, in vivo studies were performed to evaluate the penetration depth of nanocarriers using various acoustic pressures, ranging between 1.7 and 6.9MPa. Finally, a therapeutic microRNA, miR-122, was loaded into PLGA-PEG-NP and the amount of delivered miR-122 was assessed using quantitative RT-PCR. Our results show that acoustic pressures had the strongest effect on cavitation. An increase of the pressure from 0.8 to 6.9MPa resulted in a nearly 50-fold increase in cavitation in phantom experiments. In vivo, as the pressures increased from 1.7 to 6.9MPa, the amount of nanoparticles deposited in cancer xenografts was increased from 4- to 14-fold, and the median penetration depth of extravasated nanoparticles was increased from 1.3-fold to 3-fold, compared to control conditions without ultrasound, as examined on 3D confocal microscopy. When delivering miR-122 loaded PLGA-PEG-NP using optimal acoustic settings with minimum tissue damage, miR-122 delivery into tumors with ultrasound and microbubbles was 7.9-fold higher compared to treatment without ultrasound. This study demonstrates that ultrasound induced microbubble cavitation can be a useful tool for delivery of therapeutic miR loaded nanocarriers into cancer in vivo.

    View details for DOI 10.1016/j.jconrel.2015.02.018

    View details for Web of Science ID 000351696600011

    View details for PubMedID 25687306

  • Ultrasound Molecular Imaging in a Human CD276 Expression-Modulated Murine Ovarian Cancer Model. Clinical cancer research Lutz, A. M., Bachawal, S. V., Drescher, C. W., Pysz, M. A., Willmann, J. K., Gambhir, S. S. 2014; 20 (5): 1313-1322


    To develop a mouse ovarian cancer model that allows modulating the expression levels of human vascular targets in mouse xenograft tumors and to test whether expression of CD276 during tumor angiogenesis can be visualized by molecularly targeted ultrasound in vivo.CD276-expressing MILE SVEN 1 (MS1) mouse endothelial cells were engineered and used for coinjection with 2008 human ovarian cancer cells for subcutaneous xenograft tumor induction in 15 nude mice. Fourteen control mice were injected with 2008 cells only. After confirming their binding specificity in flow chamber cell attachment studies, anti-CD276 antibody-functionalized contrast microbubbles were used for in vivo CD276-targeted contrast-enhanced ultrasound imaging.CD276-targeted ultrasound imaging signal was significantly higher (P = 0.006) in mixed MS1/2008 tumors than in control tumors. Compared with control microbubbles, the ultrasound signal using CD276-targeted microbubbles was significantly higher (P = 0.002), and blocking with purified anti-CD276 antibody significantly decreased (P = 0.0096) the signal in mixed MS1/2008 tumors. Immunofluorescence analysis of the tumor tissue confirmed higher quantitative immunofluorescence signal in mixed MS1/2008 tumors than in control 2008 only tumors, but showed not significantly different (P = 0.54) microvessel density.Our novel small animal model allows for modulating the expression of human tumor-associated vascular endothelial imaging targets in a mouse host and these expression differences can be visualized noninvasively by ultrasound molecular imaging. The animal model can be applied to other human vascular targets and may facilitate the preclinical development of new imaging probes such as microbubbles targeted at human vascular markers not expressed in mice. Clin Cancer Res; 20(5); 1313-22. ©2014 AACR.

    View details for DOI 10.1158/1078-0432.CCR-13-1642

    View details for PubMedID 24389327

    View details for PubMedCentralID PMC3965293

  • Multiparametric Spectroscopic Photoacoustic Imaging of Breast Cancer Development in a Transgenic Mouse Model THERANOSTICS Wilson, K. E., Bachawal, S. V., Tian, L., Willmann, J. K. 2014; 4 (11): 1062-1071

    View details for DOI 10.7150/thno.9922

    View details for Web of Science ID 000345212900001

  • Multiparametric spectroscopic photoacoustic imaging of breast cancer development in a transgenic mouse model. Theranostics Wilson, K. E., Bachawal, S. V., Tian, L., Willmann, J. K. 2014; 4 (11): 1062-1071


    To evaluate the potential of multiparametric spectroscopic photoacoustic imaging using oxygen saturation, total hemoglobin, and lipid content to differentiate among four different breast histologies (normal, hyperplasia, ductal carcinoma in situ (DCIS), and invasive breast carcinoma) in a transgenic mouse model of breast cancer development.Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care. Mammary glands (n=251) of a transgenic mouse model of breast cancer development (FVB/N-Tg(MMTV-PyMT)634Mul) were imaged using B-mode ultrasound and spectroscopic photoacoustic imaging, analyzed for oxygen saturation, total hemoglobin, and lipid content, and processed for histological analysis. Statistical analysis was performed using one-way ANOVA, two-sample t-tests, logistic regression, and ROC analysis.Eighty-two normal, 12 hyperplastic, 96 DCIS, and 61 invasive breast carcinoma mammary glands were analyzed. Based on spectroscopic photoacoustic imaging, the oxygen saturation of hyperplasia (50.6%), DCIS (43.0%), and invasive carcinoma (46.2%) significantly increased compared to normal glands (35.5%, P <0.0001), while both total hemoglobin (P<0.01), and lipid content (P<0.0008) significantly decreased with advancing histology. In differentiating normal and hyperplasia from DCIS and invasive breast carcinoma, multiparametric imaging of oxygen saturation, lipid content, and raw photoacoustic signal at 750 nm provided an AUC value of 0.770.Multiparametric spectroscopic photoacoustic imaging is feasible and allows detection of differences in concentration of tissue chromophores among different histologies in a transgenic mouse model of breast cancer development.

    View details for DOI 10.7150/thno.9922

    View details for PubMedID 25285161

  • Earlier Detection of Breast Cancer with Ultrasound Molecular Imaging in a Transgenic Mouse Model CANCER RESEARCH Bachawal, S. V., Jensen, K. C., Lutz, A. M., Gambhir, S. S., Tranquart, F., Tian, L., Willmann, J. K. 2013; 73 (6): 1689-1698


    While there is an increasing role of ultrasound for breast cancer screening in patients with dense breast, conventional anatomical ultrasound lacks sensitivity and specificity for early breast cancer detection. In this study, we assessed the potential of ultrasound molecular imaging using clinically translatable vascular endothelial growth factor receptor type 2 (VEGFR2)-targeted microbubbles (MB(VEGFR2)) to improve the diagnostic accuracy of ultrasound in earlier detection of breast cancer and ductal carcinoma in situ (DCIS) in a transgenic mouse model [FVB/N-Tg(MMTV-PyMT)634Mul]. In vivo binding specificity studies (n = 26 tumors) showed that ultrasound imaging signal was significantly higher (P < 0.001) using MB(VEGFR2) than nontargeted microbubbles and imaging signal significantly decreased (P < 0.001) by blocking antibodies. Ultrasound molecular imaging signal significantly increased (P < 0.001) when breast tissue (n = 315 glands) progressed from normal [1.65 ± 0.17 arbitrary units (a.u.)] to hyperplasia (4.21 ± 1.16), DCIS (15.95 ± 1.31), and invasive cancer (78.1 ± 6.31) and highly correlated with ex vivo VEGFR2 expression [R(2) = 0.84; 95% confidence interval (CI), 0.72-0.91; P < 0.001]. At an imaging signal threshold of 4.6 a.u., ultrasound molecular imaging differentiated benign from malignant entities with a sensitivity of 84% (95% CI, 78-88) and specificity of 89% (95% CI, 81-94). In a prospective screening trail (n = 63 glands), diagnostic performance of detecting DCIS and breast cancer was assessed and two independent readers correctly diagnosed malignant disease in more than 95% of cases and highly agreed between each other [intraclass correlation coefficient (ICC) = 0.98; 95% CI, 97-99]. These results suggest that VEGFR2-targeted ultrasound molecular imaging allows highly accurate detection of DCIS and breast cancer in transgenic mice and may be a promising approach for early breast cancer detection in women.

    View details for DOI 10.1158/0008-5472.CAN-12-3391

    View details for Web of Science ID 000316187500006

    View details for PubMedID 23328585

    View details for PubMedCentralID PMC3602408

  • Enhanced antiproliferative and apoptotic response to combined treatment of gamma-tocotrienol with erlotinib or gefitinib in mammary tumor cells BMC CANCER Bachawal, S. V., Wali, V. B., Sylvester, P. W. 2010; 10


    Aberrant ErbB receptor signaling is associated with various types of malignancies. gamma-Tocotrienol is a member of the vitamin E family of compounds that displays potent anticancer activity that is associated with suppression in ErbB receptor phosphorylation and mitogenic signaling. Erlotinib and gefitinib are tyrosine kinase inhibitors that block ErbB1 receptor activation, whereas trastuzumab is a monoclonal antibody that has been designed to specifically inhibit ErbB2 receptor activation. However, the clinical effectiveness of these agents have been disappointing because of cooperation between different ErbB family members that can rescue cancer cells from agents directed against a single ErbB receptor subtype. It was hypothesized that targeting multiple ErbB receptor subtypes with combined treatment of gamma-tocotrienol and ErbB receptor inhibitors would provide greater anticancer effects than monotherapy targeting only a single ErbB receptor subtype.Highly malignant mouse +SA mammary epithelial cells were maintained in culture on serum-free defined media containing 10 ng/ml EGF as a mitogen. Cell viability wase determined by MTT assay, whereas Western blot and immunofluorescent staining was used to determine treatment effects on ErbB receptor subtype level and activation. Treatment-induced apoptosis was determined using annexin V staining and Western blot analysis of cleaved caspase-3 and PARP levels.Treatment with 3.5 microM gamma-tocotrienol, 0.5 microM erlotinib or 1.0 microM gefitinib alone, significantly inhibited +SA tumor cell growth. Combined treatment with subeffective doses of erlotinib (0.25 microM) or gefitinib (0.5 microM) with subeffective doses of gamma-tocotrienol (0.5-3.0 microM) significantly inhibited the growth and induced apoptosis in a dose-responsive manner. Trastuzumab treatment alone or in combination had no effect on +SA cell growth and viability. Combined treatment of gamma-tocotrienol with erlotinib or gefitinib also cause a large decrease in ErbB3, ErbB4, and to a lesser extent ErbB2 receptor levels, and EGF-dependent ErbB2-4 tyrosine phosphorylation (activation), but had no effect on ErbB1 receptor levels or activation.Combination treatment of gamma-tocotrienol with specific ErbB receptor inhibitors is more effective in reducing mammary tumor cell growth and viability than high dose monotherapy, suggesting that targeting multiple ErbB receptors with combination therapy may significantly improve the therapeutic response in breast cancer patients.

    View details for DOI 10.1186/1471-2407-10-84

    View details for Web of Science ID 000275797100001

    View details for PubMedID 20211018

  • Combined gamma-Tocotrienol and Erlotinib/Gefitinib Treatment Suppresses Stat and Akt Signaling in Murine Mammary Tumor Cells ANTICANCER RESEARCH Bachawal, S. V., Wali, V. B., Sylvester, P. W. 2010; 30 (2): 429-437


    Heterodimer cooperation between ErbB receptors has limited clinical usefulness of receptor tyrosine kinase inhibitors (TKIs), erlotinib and gefitinib in the treatment of cancer. However, combination treatment of TKIs with gamma-tocotrienol targets multiple ErbB receptors and significantly inhibit +SA murine mammary tumor cell growth.Cell proliferation was determined by tetrazolium (MTT) assay and immunofluorescent Ki-67 staining. Western blot analysis was used to determine treatment effects on epidermal growth factor (EGF)-dependent mitogenic signaling.Combined treatment of 3 microM gamma-tocotrienol with 0.25 microM erlotinib or 0.5 microM gefitinib significantly inhibited +SA cell growth and reduced cyclin D1 and phosphorylated (active) Pdk-1, Akt, Stat3 and Stat5 levels.Combined treatment of gamma-tocotrienol with erlotinib or gefitinib prevents ErbB receptor heterodimer cooperation and inhibits EGF-dependent mitogenic signaling in +SA murine mammary tumor cells. These findings strongly suggest that combination treatment may significantly improve therapeutic responsiveness in breast cancer patients.

    View details for Web of Science ID 000275821200022

    View details for PubMedID 20332450

  • Endoplasmic reticulum stress mediates gamma-tocotrienol-induced apoptosis in mammary tumor cells APOPTOSIS Wali, V. B., Bachawal, S. V., Sylvester, P. W. 2009; 14 (11): 1366-1377


    gamma-Tocotrienol, a member of the vitamin E family of compounds, induces apoptosis in a variety of cancer cell types. However, previous studies have clearly demonstrated that gamma-tocotrienol-induced apoptosis in neoplastic mouse +SA mammary epithelial cells is not mediated through mitochondrial stress or death receptor apoptotic signaling. Therefore, studies were conducted to determine the role of endoplasmic reticulum (ER) stress in mediating gamma-tocotrienol-induced apoptosis in +SA mammary tumor cells. Treatment with 15-40 microM gamma-tocotrienol induced +SA cell death in a dose-responsive manner, and these effects were associated with a corresponding increase in poly (ADP-ribose) polymerase (PARP)-cleavage and activation of protein kinase-like endoplasmic reticulum kinase/eukaryotic translational initiation factor/activating transcription factor 4 (PERK/eIF2alpha/ATF-4) pathway, a marker of ER stress response. These treatments also caused a large increase in C/EBP homologous protein (CHOP) levels, a key component of ER stress mediated apoptosis that increases expression of tribbles 3 (TRB3). Knockdown of CHOP by specific siRNAs attenuated gamma-tocotrienol-induced PARP-cleavage, CHOP and TRB3 expression. gamma-Tocotrienol treatment also reduced full-length caspase-12 levels, an indication of caspase-12 cleavage and activation. Intracellular levels of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase, an ER-transmembrane enzyme catalyzing the synthesis of mevalonate, decreased following gamma-tocotrienol treatment, but combined treatment with mevalonate did not reverse gamma-tocotrienol-induced apoptosis, suggesting that a decrease in HMGCoA reductase activity is not required for gamma-tocotrienol induced apoptosis. These results demonstrate that ER stress apoptotic signaling is associated with gamma-tocotrienol-induced apoptosis in +SA mammary tumor cells.

    View details for DOI 10.1007/s10495-009-0406-y

    View details for Web of Science ID 000270540800011

    View details for PubMedID 19771520

  • Suppression in Mevalonate Synthesis Mediates Antitumor Effects of Combined Statin and gamma-Tocotrienol Treatment LIPIDS Wali, V. B., Bachawal, S. V., Sylvester, P. W. 2009; 44 (10): 925-934


    Statins directly inhibit 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) activity, while gamma-tocotrienol, an isoform of vitamin E, enhances the degradation and reduces cellular levels of HMGR in various tumor cell lines. Since treatment with statins or gamma-tocotrienol alone induced a dose-responsive inhibition, whereas combined treatment with subeffective doses of these agents resulted in a synergistic inhibition in +SA mammary tumor cell growth, studies were conducted to investigate the role of the HMGR pathway in mediating the antiproliferative effects of combined low dose statin and gamma-tocotrienol. Treatment with 8 microM simvastatin inhibited cell growth and isoprenylation of Rap1A and Rab6, and supplementation with 2 microM mevalonate reversed these effects. However, the growth inhibitory effects of 4 microM gamma-tocotrienol were not dependent upon suppression in mevalonate synthesis. Treatment with subeffective doses of simvastatin (0.25 microM), lovastatin (0.25 microM), mevastatin (0.25 microM), pravastatin (10 microM), or gamma-tocotrienol (2 muM) alone had no effect on protein prenylation or mitogenic signaling, whereas combined treatment with these agents resulted in a significant inhibition in +SA cell growth, and a corresponding decrease in total HMGR, Rap1A and Rab6 prenylation, and MAPK signaling, and mevalonate supplementation reversed these effects. These findings demonstrate that the synergistic antiproliferative effects of combined low dose statin and gamma-tocotrienol treatment are directly related to an inhibition in HMGR activity and subsequent suppression in mevalonate synthesis.

    View details for DOI 10.1007/s11745-009-3344-0

    View details for Web of Science ID 000270895100006

    View details for PubMedID 19777282

  • Combined Treatment of gamma-Tocotrienol with Statins Induce Mammary Tumor Cell Cycle Arrest in G1 EXPERIMENTAL BIOLOGY AND MEDICINE Wali, V. B., Bachawal, S. V., Sylvester, P. W. 2009; 234 (6): 639-650


    Statins and gamma-tocotrienol (a rare isoform of vitamin E) both inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase activity and display anticancer activity. However, clinical application of statins has been limited by high dose toxicity. Previous studies showed that combined statin and gamma-tocotrienol treatment synergistically inhibits growth of highly malignant +SA mammary epithelial cells in culture. To investigate the mechanism mediating this growth inhibition, studies were conducted to determine the effect of combination low dose gamma-tocotrienol and statin treatment on +SA mammary tumor cell cycle progression. Treatment with 0.25 microM simvastatin, lovastatin, mevastatin, 10 microM pravastatin or 2.0 microM gamma-tocotrienol alone had no effect, while combined treatment of individual statins with gamma-tocotrienol significantly inhibited +SA cell proliferation during the 4-day culture period. Flow cytometric analysis demonstrated that combined treatment induced cell cycle arrest in G1. Additional studies showed that treatment with 0.25 microM simvastatin or 2 microM gamma-tocotrienol alone had no effect on the relative intracellular levels of cyclin D1, CDK2, CDK4 and CDK6, but combined treatment caused a large reduction in cyclin D1 and CDK2 levels. Combined treatments also caused a relatively large increase in p27, but had no effect on p21 and p15 levels, and resulted in a large reduction in retinoblastoma (Rb) protein phosphorylation at ser780 and ser807/811. Similar effects were observed following combined treatment of gamma-tocotrienol with low doses of lovastatin, mevastatin and pravastatin. These findings demonstrate that combination low dose statin and gamma-tocotrienol treatment induced mammary tumor cell cycle arrest at G1, resulting from an increase in p27 expression, and a corresponding decrease in cyclin D1, CDK2, and hypophosphorylation of Rb protein. These findings suggest that combined treatment of statins with gamma-tocotrienol may provide significant health benefits in the treatment of breast cancer in women, while avoiding myotoxicity associated with high dose statin monotherapy.

    View details for DOI 10.3181/0810-RM-300

    View details for Web of Science ID 000266770400005

    View details for PubMedID 19359655

  • Antiproliferative Triterpenes from Melaleuca ericifolia JOURNAL OF NATURAL PRODUCTS Bar, F. M., Zaghloul, A. M., Bachawal, S. V., Sylvester, P. W., Ahmad, K. F., El Sayed, K. A. 2008; 71 (10): 1787-1790


    Three new 28-norlupane triterpenes, 28-norlup-20(29)-en-3beta-hydroxy-17beta-hydroperoxide (1), 28-norlup-20(29)-en-3beta-hydroxy-17alpha-hydroperoxide (2), and 20 S-17beta,29-epoxy-28-norlupan-3beta-ol (3), were isolated from the leaves of Melaleuca ericifolia along with eight known pentacyclic triterpenes. The structures of the new compounds were elucidated by spectroscopic methods including 1D and 2D NMR spectroscopy and mass spectrometry. The isolated triterpenes were evaluated for antiproliferative activity against the malignant +SA mammary epithelial cell line.

    View details for DOI 10.1021/np800360a

    View details for Web of Science ID 000260384400024

    View details for PubMedID 18826277