Dr. Sunwoo was born and raised in St. Louis, Missouri. He received his undergraduate degree from Brown University in Providence, Rhode Island and his medical degree from Washington University in St. Louis, Missouri. He completed his training in Otolaryngology – Head and Neck Surgery at Washington University. Dr. Sunwoo has been at Stanford University since 2008, and his clinical focus is on the surgical management of head and neck cancer, specifically focusing on melanoma and neoplasms of the thyroid and parathyroid glands. He is a member of the Pigmented Lesions and Melanoma Clinic and the Melanoma Working Group at Stanford. He is also the co-founder of the Stanford Thyroid and Parathyroid Tumor Board.
In addition to his clinical work, Dr. Sunwoo is the Director of Head and Neck Cancer Research at Stanford University and the principal investigator of an NIH-funded laboratory in the Stanford Cancer Institute. His research is focused on three primary areas: (1) the immune response to cancer, particularly a tumorigenic population of cells within malignancies called cancer stem cells; (2) the biology and developmental programs of a special lymphocyte population involved in innate immunity called natural killer (NK) cells; and (3) intra-tumor and inter-tumor heterogeneity in head and neck cancer.
- Cancer > Cutaneous (Dermatologic) Oncology
- Cancer > Head and Neck Cancer
- Thyroid Neoplasms
- Parathyroid Neoplasms
- Tongue Neoplasms
- Otolaryngology - Head & Neck Surgery (Ear, Nose and Throat)
- Thyroid Nodule
- Parotid Neoplasms
- Cancer of the Salivary Gland
Member, Tumor Biology & Imaging Task Force, Head and Neck Steering Committee of the National Cancer Institute, NIH (2010 - 2011)
Member, CORE Grants Study Section, American Academy of Otolaryngology Head and Neck Surgery (2009 - Present)
Member, Research Committee, American Head and Neck Society (2010 - 2013)
Member, Metastatic and Recurrent Head and Neck Disease Task Force, Head and Neck Steering Committee of the National Cancer Institute, NIH (2011 - Present)
Member, Pigmented Lesion and Melanoma Program, Stanford University School of Medicine (2011 - Present)
Co-Director, Thyroid and Parathyroid Tumor Board, Stanford University School of Medicine (2011 - Present)
Director of Head and Neck Cancer Research, Stanford University School of Medicine, Dept. of Otolaryngology (2013 - Present)
Honors & Awards
Sigma Xi, Brown University (1989)
Louis and Dorothy Kovitz Prize in Surgery, Washington University (1993)
Resident Research Award, Washington University (1997, 1999, 2000)
Young Investigator Award, American Head and Neck Society (2000)
Alpha Omega Alpha, Washington University (2003)
Chief Resident Teaching Award, Washington University (2003)
K08 Award, National Institutes of Health (2004)
Faculty Teacher of the Year, Dept. of Otolaryngology, Stanford University (2012)
Top Doctors, Castle Connolly (2013-present)
Best Doctors in America, Best Doctors, Inc. (2009-present)
Postdoc Research Fellowship, Washington University, Immunology (2008)
Residency:Washington University School Of Medicine (2003) MO
Medical Education:Washington University School Of Medicine (1993) MO
Board Certification: Otolaryngology, American Board of Otolaryngology (2004)
Fellowship:National Institutes of Health (2000) MD
M.D., Washington University, Medicine (1993)
Sc.B., Brown University, Biochemistry (1989)
Current Research and Scholarly Interests
My laboratory is focused on two primary areas of research: (1) the immune response to head and neck cancer and to a tumorigenic population of cells within these malignancies called cancer stem cells; (2) the developmental programs of a special lymphocyte population involved in innate immunity called natural killer (NK) cells; and (3) intra-tumor and inter-tumor heterogeneity.
The overarching goal of my laboratory is to understand how NK cells, in the broader context of the host immune system, protect against developing and metastasizing tumor cells, especially a rare population of tumor-initiating cells called cancer stem cells. These tumorigenic cells have been isolated from a number of solid tumor malignancies, including human head and neck cancer. Heterogeneity of immune potency between individuals with these malignancies is well accepted but poorly understood. The work in my laboratory will address the questions of how and why the immune system can respond to and control malignant cells in some contexts but not in others. Clarity of the underlying basis for these differences would potentially explain why certain individuals are more susceptible to cancer, lead to better screening strategies, and ultimately provide much needed insight into how the host immune system can be manipulated to control cancer.
Identification and Characterization of Novel Proteins and Genes in Head and Neck Cancer
Through this study, we hope to learn more about the mechanisms, which may contribute to development and progression of head and neck cancer. The long-term goal of this study will be to develop new strategies and drugs for the diagnosis and treatment of head and neck cancer.
Talactoferrin in Treating Patients With Relapsed or Refractory Non-Small Cell Lung Cancer or Squamous Cell Head and Neck Cancer
This phase I trial studies how well talactoferrin works in treating patients with relapsed or refractory non-small cell lung cancer (NSCLC) or squamous cell head and neck cancer. Biological therapies, such as talactoferrin, may stimulate the immune system in different ways and stop tumor cells from growing
Stanford is currently not accepting patients for this trial. For more information, please contact Melanie San Pedro-Salcedo, (650) 724 - 1388.
Identification of Secreted Markers for Tumor Hypoxia in Patients With Head and Neck or Lung Cancers
The purpose of this study is to identify and confirm new blood and tissue markers for prognosis and tumor hypoxia. Tumor hypoxia, or the condition of low oxygen in the tumor, has been shown to increase the risk of tumor spread and enhance tumor resistance to the standard treatment of radiation and chemotherapy in head and neck and lung cancers. We have recently identified several proteins or markers in the blood and in tumors (including osteopontin, lysyl oxidase, macrophage inhibiting factor and proteomic technology) in the laboratory that may be able to identify tumors with low oxygen levels or more aggressive behaving tumors.
NBI to Characterize Patterns of Vascular Supply Within Lymphoepithelial Mucosa in Oropharyngeal Cancer
The purpose of this study is to characterize the blood supply at the base of the tongue and within the tonsil region. We hypothesize that high-resolution Narrow Band Imaging (NBI) will improve the diagnosis of oropharyngeal carcinoma (OPC). The goal is to provide the better assessment of tumor and thus providing better preoperative expectations to patients with OPC or tumor extent prior to radiation therapy.
Imaging and Biomarkers of Hypoxia in Solid Tumors
We hope to find safer, noninvasive methods for measuring tumor hypoxia. Hypoxia, meaning a lack of oxygen, has been associated strongly with a wide range of human cancers. Hypoxia occurs when tumor growth exceeds the ability of blood vessels to supply the tumor with oxygenated blood. It is currently understood that hypoxic tumors are more aggressive. Current methods for measuring hypoxia include invasive procedures such as tissue biopsy, or insertion of an electrode into the tumor. EF5-PET may be a non-invasive way to make this measurement.
Independent Studies (12)
- Directed Reading in Cancer Biology
CBIO 299 (Aut, Win, Spr, Sum)
- Directed Reading in Immunology
IMMUNOL 299 (Aut, Win, Spr, Sum)
- Directed Reading in Otolaryngology
OTOHNS 299 (Aut, Win, Spr, Sum)
- Early Clinical Experience in Immunology
IMMUNOL 280 (Aut, Win, Spr, Sum)
- Graduate Research
CBIO 399 (Aut, Win, Spr, Sum)
- Graduate Research
IMMUNOL 399 (Aut, Win, Spr, Sum)
- Graduate Research
OTOHNS 399 (Aut, Win, Spr, Sum)
- Medical Scholars Research
OTOHNS 370 (Aut, Win, Spr, Sum)
- Teaching in Cancer Biology
CBIO 260 (Spr)
- Teaching in Immunology
IMMUNOL 290 (Aut, Win, Spr, Sum)
- Undergraduate Research
IMMUNOL 199 (Aut, Win, Spr, Sum)
- Undergraduate Research
OTOHNS 199 (Aut, Win, Spr, Sum)
- Directed Reading in Cancer Biology
CD44+ cells in head and neck squamous cell carcinoma suppress T cell-mediated immunity by selective constitutive and inducible expression of PD-L1.
Clinical cancer research : an official journal of the American Association for Cancer Research
Human tumors consist of heterogeneous populations of cells with distinct marker expression and functional properties. In squamous cell carcinoma of the head and neck (SCCHN), CD44 is a well-characterized marker of a resilient subpopulation of cells associated with increased tumorigenesis, radioresistance, and chemoresistance. Evidence indicates that these cells have an immune suppressive phenotype; however, mechanisms have been elusive.Using primary human SCCHN tumor samples and patient-derived xenografts, we examined the phenotypes of subsets of tumor cells and investigated mechanisms regulating their immunogenicity.CD44+ cells in primary human SCCHN were found to have an epithelial-to-mesenchymal (EMT) phenotype and were less immunogenic than CD44- cells when cultured with autologous CD8+ tumor-infiltrating T cells. Selective expression of the programmed death-ligand 1 (PD-L1) was observed on CD44+ cells compared to CD44- cells and was associated with constitutive phosphorylation of STAT3 on CD44+ cells. Importantly, inhibition of STAT3 decreased expression of PD-L1 on CD44+ cells. Interferon-γ (IFNγ) treatment preferentially induced even further PD-L1 expression on CD44+ cells and was associated with enhanced IFNγ receptor expression and phosphorylation of STAT1. Finally, the decreased immunogenicity of CD44+ cells was partially reversed by antibody blockade of the programmed death 1 (PD-1) receptor, indicating that the differences in PD-L1 expression between CD44+ and CD44- cells are biologically and clinically relevant.Our findings provide a mechanism by which long-lived CD44+ tumor-initiating cells can selectively evade host immune responses and provide rationale for targeting the PD-1 pathway in the adjuvant therapy setting of SCCHN.
View details for DOI 10.1158/1078-0432.CCR-15-2665
View details for PubMedID 26864211
- Tumor Ulceration Does Not Fully Explain Sex Disparities in Melanoma Survival among Adolescents and Young Adults. journal of investigative dermatology 2015; 135 (12): 3195-3197
A prospective study of electronic quality of life assessment using tablet devices during and after treatment of head and neck cancers
2015; 51 (12): 1132-1137
Electronic data collection is increasingly used for quality of life (QOL) assessments in the field of oncology. It is important to assess the feasibility of these new data capture technologies.Patients at our institution who were 18years or older with a pathological diagnosis of head and neck cancer were prospectively enrolled. Each patient completed two questionnaires [EORTC-QLQ-C30 and EORTC-QLQ-H&N35] administered on a touch-screen tablet device (iPad™) at initial consult, during treatment, at the completion of treatment and at each subsequent follow up visit for one year after treatment.A total of 50 patients were included in this study. Although all patients completed the surveys at the initial consult, 86% of initially enrolled patients completed surveys at the end of radiation treatment, and 48% of initially enrolled patients completed surveys by the fourth follow-up visit. Average time to complete the survey for all patients over all time points was 9.8min (standard deviation 6.1). Age as a continuous variable was significantly associated with time for survey completion (p<0.001), with older age associated with longer survey completion times.QOL assessment using tablet devices in head and neck cancer patients is feasible, but may be more challenging in elderly patients. Patients ⩾70years old may benefit from more assistance with electronic forms and should be allotted more time for completing tablet-based QOL surveys.
View details for DOI 10.1016/j.oraloncology.2015.10.003
View details for Web of Science ID 000366534000017
- Immunotherapy for Head and Neck Squamous Cell Carcinoma HEMATOLOGY-ONCOLOGY CLINICS OF NORTH AMERICA 2015; 29 (6): 1033-?
beta-Radioluminescence Imaging: A Comparative Evaluation with Cerenkov Luminescence Imaging
JOURNAL OF NUCLEAR MEDICINE
2015; 56 (9): 1458-1464
Cerenkov luminescence imaging (CLI) can provide high-resolution images of (18)F-FDG-avid tumors but requires prolonged acquisition times because of low photon sensitivity. In this study, we proposed a new modality, termed β-radioluminescence imaging (β-RLI), which incorporates a scintillator with a γ-rejection strategy for imaging β particles. We performed a comparative evaluation of β-RLI with CLI in both in vitro and in vivo systems.Using in vitro phantoms, we characterized the photon sensitivity and resolution of CLI and β-RLI. We also conducted a series of in vivo experiments with xenograft mouse models using both amelanotic (A375, UMSCC1-Luc) and melanotic (B16F10-Luc) cell lines. The B16F10 and UMSCC1 cell lines were transfected with the luciferase gene (Luc). CLI was acquired over 300 s, and β-RLI was acquired using two 10-s acquisitions. We correlated (18)F -: FDG activities, as assessed by PET, with tumor radiances for both β-RLI and CLI. We also compared tumor signal-to-background ratios (SBRs) between these modalities for amelanotic and melanotic tumors.For in vitro experiments, the photon sensitivity for β-RLI was 560-fold greater than that for CLI. However, the spatial resolution for β-RLI (4.4 mm) was inferior to that of CLI (1.0 mm). For in vivo experiments, correlations between (18)F-FDG activity and tumor radiance were 0.52 (P < 0.01) for β-RLI, 0.81 (P = 0.01) for amelanotic lesions with CLI, and -0.08 (negative contrast; P = 0.80) for melanotic lesions with CLI. Nine of 13 melanotic lesions had an SBR less than 1 for CLI, despite an SBR greater than 1 among all lesions for β-RLI.β-RLI can produce functional images of both amelanotic and melanotic tumors in a shorter time frame than CLI. Further engineering developments are needed to realize the full clinical potential of this modality.
View details for DOI 10.2967/jnumed.115.158337
View details for Web of Science ID 000361153000036
Targeting Toll-like receptor 2 inhibits growth of head and neck squamous cell carcinoma
2015; 6 (12): 9897-9907
Infection-driven inflammation has been proposed to be involved in the tumorigenesis of head and neck squamous cell carcinoma (HNSCC). Oral HNSCC is often colonized with microbes such as gram-positive bacteria and yeast, where ligands derived from their wall components have been shown to specifically bind to Toll-like receptor 2 (TLR2). Although TLR2 has been described to be expressed in oral HNSCC, its function has not been well characterized. Here, we show the expression of TLR2 in both HNSCC cell lines and primary patient-derived HNSCC xenograft tumors. Activation of TLR2 with a yeast-derived ligand of TLR2, zymosan, promoted organoid formation in an ex vivo model of tumor growth, while blockade with anti-TLR2 antibodies inhibited organoid formation. Zymosan also induced phosphorylation of ERK and the p65 subunit of NF-κB, which was inhibited in the presence of anti-TLR2 antibodies, indicating that this receptor is functional in HNSCC and that the signaling through these pathways is intact. TLR2 blockade also inhibited growth of human xenografted tumors in immunodeficient mice. In summary, our data show that TLR2 is a functional receptor expressed in human HNSCC that plays a direct pro-tumorigenic role, and that it can be therapeutically targeted with blocking antibodies to reduce tumor growth.
View details for Web of Science ID 000358874600022
View details for PubMedID 25846753
Regulation of ribosomal RNA synthesis in T cells: requirement for GTP and Ebp1
2015; 125 (16): 2519-2529
Mycophenolic acid (MPA) is the active metabolite of Mycophenolate Mofeteil (MMF), an effective immunosuppressive drug. Both MPA and MMF are highly specific inhibitors of guanine nucleotide synthesis and of T cell activation. However, the mechanism by which guanine nucleotide depletion suppresses T cell activation is unknown. Depletion of GTP inhibits ribosomal RNA synthesis in T cells by inhibiting TIF-IA, a GTP-binding protein that recruits RNA Polymerase I to the ribosomal DNA promoter. TIF-IA-GTP binds the ErbB3 binding protein 1 (Ebp1) and together they enhance the transcription of proliferating cell nuclear antigen (PCNA). GTP binding by TIF-IA and Ebp1 phosphorylation by protein kinase C delta are both required for optimal PCNA expression. The PKC inhibitor Sotrastaurin markedly potentiates the inhibition of rRNA synthesis, PCNA expression, and T cell activation induced by MPA, suggesting that the combination of the two agents are more highly effective than either alone in inducing immunosuppression.
View details for DOI 10.1182/blood-2014-12-616433
View details for Web of Science ID 000354751700013
CCR 20th anniversary commentary: Preclinical study of proteasome inhibitor bortezomib in head and neck cancer.
Clinical cancer research
2015; 21 (5): 942-943
In a study published in the May 1, 2001, issue of Clinical Cancer Research, Sunwoo and colleagues provided evidence for proteasome inhibition of NF-κB and tumorigenesis, supporting early-phase clinical trials in solid malignancies of the upper aerodigestive tract. Subsequent clinical studies uncovered a dichotomy of responses in patients with hematopoietic and solid malignancies, and the mechanisms of resistance. Clin Cancer Res; 21(5); 942-3. ©2015 AACR. See related article by Sunwoo et al., Clin Cancer Res 2001;7(5) May 2001;1419-28.
View details for DOI 10.1158/1078-0432.CCR-14-2550
View details for PubMedID 25733706
Aberrant Lymphatic Drainage and Risk for Melanoma Recurrence after Negative Sentinel Node Biopsy in Middle-aged and Older Men.
Head & neck
Background Aberrant lymphatic drainage is believed to contribute to the high recurrence rate of head and neck melanomas. This study aimed to identify the clinical significance of unexpected lymphatic drainage patterns. Methods A single institution retrospective analysis was performed of middle-aged and older males (mean age 66.2 years, range 41-87 years) who underwent successful lymphoscintigraphy with sentinel node (SLN) biopsy from 1997 through 2012. Node status, distribution, and recurrence were assessed comparing patients with expected and unexpected drainage patterns. Results Sixty-six patients were identified with 55.8 months median follow-up (range 5.6-206.1 months). Unexpected SLN drainage was associated with multiple basin drainage (p < 0.01) and greater recurrence after negative SLN biopsy (p = 0.03). Both groups had similar anatomic distribution, SLN sampling, histopathologic characteristics, follow-up, and survival. Conclusion Lymphatic drainage differing from expected patterns is associated with greater recurrence after negative SLN biopsy in middle-aged and older males. This article is protected by copyright. All rights reserved.
View details for DOI 10.1002/hed.24094
View details for PubMedID 25914266
Ameloblastoma: a clinical review and trends in management.
European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery
Ameloblastoma is a rare odontogenic neoplasm of the mandible and maxilla, with multiple histologic variants, and high recurrence rates if improperly treated. The current mainstay of treatment is wide local excision with appropriate margins and immediate reconstruction. Here we review the ameloblastoma literature, using the available evidence to highlight the change in management over the past several decades. In addition, we explore the recent molecular characterization of these tumors which may point towards new potential avenues of personalized treatment.
View details for DOI 10.1007/s00405-015-3631-8
View details for PubMedID 25926124
CD271 is a functional and targetable marker of tumor-initiating cells in head and neck squamous cell carcinoma
2014; 5 (16): 6854-6866
Tumor-initiating cells (TICs) in squamous cell carcinoma of the head and neck (SCCHN) are best characterized by their surface expression of CD44. Although there is great interest in identifying strategies to target this population, no marker of these cells has been found to be functionally active. Here, we examined the expression of the purported marker of normal human oral epithelial stem cells, CD271. We show that CD271 expression is restricted to a subset of the CD44+ cells. Using xenograft assays, we show that the CD44+CD271+ subpopulation contains the most tumorigenic cells. Loss of CD271 function results in a block in the G2-M phase of the cell cycle and a profound negative impact on the capacity of these cells to initiate tumor formation in vivo. Incubation with recombinant NGF results in enhanced phosphorylation of Erk, providing additional evidence that CD271 is functionally active. Finally, incubation of SCCHN cells with antibody to CD271 results in decreased Erk phosphorylation and decreased tumor formation in vivo. Thus, our data are the first to demonstrate that CD271 more specifically identifies the TIC subpopulation within the CD44+ compartment in SCCHN and that this receptor is a functionally active and targetable molecule.
View details for Web of Science ID 000347920100028
Targeting CD137 enhances the efficacy of cetuximab.
journal of clinical investigation
2014; 124 (6): 2668-2682
Treatment with cetuximab, an EGFR-targeting IgG1 mAb, results in beneficial, yet limited, clinical improvement for patients with head and neck (HN) cancer as well as colorectal cancer (CRC) patients with WT KRAS tumors. Antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells contributes to the efficacy of cetuximab. The costimulatory molecule CD137 (4-1BB) is expressed following NK and memory T cell activation. We found that isolated human NK cells substantially increased expression of CD137 when exposed to cetuximab-coated, EGFR-expressing HN and CRC cell lines. Furthermore, activation of CD137 with an agonistic mAb enhanced NK cell degranulation and cytotoxicity. In multiple murine xenograft models, including EGFR-expressing cancer cells, HN cells, and KRAS-WT and KRAS-mutant CRC, combined cetuximab and anti-CD137 mAb administration was synergistic and led to complete tumor resolution and prolonged survival, which was dependent on the presence of NK cells. In patients receiving cetuximab, the level of CD137 on circulating and intratumoral NK cells was dependent on postcetuximab time and host FcyRIIIa polymorphism. Interestingly, the increase in CD137-expressing NK cells directly correlated to an increase in EGFR-specific CD8+ T cells. These results support development of a sequential antibody approach against EGFR-expressing malignancies that first targets the tumor and then the host immune system.
View details for DOI 10.1172/JCI73014
View details for PubMedID 24837434
Epstein-Barr Virus Nuclear Antigen 1 (EBNA1) Protein Induction of Epithelial-Mesenchymal Transition in Nasopharyngeal Carcinoma Cells
2014; 120 (3): 363-372
The Epstein-Barr virus (EBV)-encoded EB nuclear antigen 1 (EBNA1) protein is required for maintenance and transmission of the viral episome in EBV-infected cells. The objective of this study was to investigate the role of EBNA1 protein in nasopharyngeal carcinoma (NPC).Tissue samples from 48 patients with NPC and 12 patients with chronic nasopharyngitis were subjected to immunohistochemical analysis of EBNA1 expression. EBNA1 combinational DNA was used to overexpress EBNA1 protein in NPC cell lines to assess tumor cell epithelial-mesenchymal transition (EMT), colony formation, migration and invasion, and gene expression.EBNA1 protein was highly expressed in NPC tissue specimens, and its expression was associated with NPC lymph node metastasis. EBNA1 expression affected NPC cell morphology and the expression of EMT markers in vitro. Furthermore, overexpression of EBNA1 inhibited the expression of microRNA 200a (miR-200a) and miR-200b and, in turn, up-regulated expression of their target genes, zinc finger E-box binding homeobox 1 ( ZEB1) and ZEB2, which are well known mediators of EMT. In addition, EBNA1-regulated miR-200a and miR-200b expression was mediated by transforming growth factor-β1.The current findings provided novel insight into the vital role of EBNA1 in manipulating a molecular switch of EMT in EBV-positive NPC cells.
View details for DOI 10.1002/cncr.28418
View details for Web of Science ID 000330267700009
View details for PubMedID 24190575
Cancer Immunosurveillance and Immunoediting by Natural Killer Cells
2013; 19 (6): 483-489
Cancer immunosurveillance eradicates certain neoplasms, but the selective pressure exerted by this active surveillance leads to the emergence of immune evasive tumor clones in a process called cancer immunoediting. Natural killer (NK) cells are potent effectors of cancer immunoediting and can destroy tumors directly via exocytosis of cytotoxic granules or indirectly by producing interferon γ to activate M1 and TH1 immune responses. This review gathers current knowledge of NK immunosurveillance of primary tumors induced in mice and highlights the importance of NK immunosurveillance for human cancers. Evidence of NK immunoediting, as revealed by studies using NK-deficient models, demonstrates how exposure to NK cells engenders modification of cancer immunogenicity to permit survival and progression of the tumor clone in an immunocompetent environment.
View details for Web of Science ID 000330474600005
View details for PubMedID 24270347
Modulation of natural killer cell antitumor activity by the aryl hydrocarbon receptor
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2013; 110 (30): 12391-12396
The aryl hydrocarbon receptor (AhR) has become increasingly recognized for its role in the differentiation and activity of immune cell subsets; however, its role in regulating the activity of natural killer (NK) cells has not been described. Here, we show that AhR expression is induced in murine NK cells upon cytokine stimulation. We show that in the absence of AhR, NK cells have reduced cytolytic activity and reduced capacity to control RMA-S tumor formation in vivo, despite having normal development and maturation markers. Although AhR was first identified to bind the xenobiotic compound dioxin, AhR is now known to bind a variety of natural exogenous (e.g., dietary) and endogenous ligands. We show that activation of AhR with an endogenous tryptophan derivative, 6-formylindolo[3,2-b]carbazole, potentiates NK cell IFN-γ production and cytolytic activity. Further, administration of 6-formylindolo[3,2-b]carbazole in vivo enhances NK cell control of tumors in an NK cell- and AhR-dependent manner. Finally, similar effects on NK cell potency occur with AhR dietary ligands, potentially explaining the numerous associations that have been observed in the past between diet and NK cell function. Our studies introduce AhR as another regulator of NK cell activity in vivo.
View details for DOI 10.1073/pnas.1302856110
View details for Web of Science ID 000322112300059
Impact of positron emission tomography/computed tomography surveillance at 12 and 24 months for detecting head and neck cancer recurrence.
2013; 119 (7): 1349-1356
In head and neck cancer (HNC), 3-month post-treatment positron emission tomography (PET)/computed tomography (CT) reliably identifies persistent/recurrent disease. However, further PET/CT surveillance has unclear benefit. The impact of post-treatment PET/CT surveillance on outcomes is assessed at 12 and 24 months.A 10-year retrospective analysis of HNC patients was carried out with long-term serial imaging. Imaging at 3 months included either PET/CT or magnetic resonance imaging, with all subsequent imaging comprised of PET/CT. PET/CT scans at 12 and 24 months were evaluated only if preceding interval scans were negative. Of 1114 identified patients, 284 had 3-month scans, 175 had 3- and 12-month scans, and 77 had 3-, 12-, and 24-month scans.PET/CT detection rates in clinically occult patients were 9% (15 of 175) at 12 months, and 4% (3 of 77) at 24 months. No difference in outcomes was identified between PET/CT-detected and clinically detected recurrences, with similar 3-year disease-free survival (41% vs 46%, P = .91) and 3-year overall survival (60% vs 54%, P = .70) rates. Compared with 3-month PET/CT, 12-month PET/CT demonstrated fewer equivocal reads (26% vs 10%, P < .001). Of scans deemed equivocal, 6% (5 of 89) were ultimately found to be positive.HNC patients with negative 3-month imaging appear to derive limited benefit from subsequent PET/CT surveillance. No survival differences were observed between PET/CT-detected and clinically detected recurrences, although larger prospective studies are needed for further investigation.
View details for DOI 10.1002/cncr.27892
View details for PubMedID 23225544
Epigenetically mediated pathogenic effects of phenanthrene on regulatory T cells.
Journal of toxicology
2013; 2013: 967029-?
Phenanthrene (Phe), a polycyclic aromatic hydrocarbon (PAH), is a major constituent of urban air pollution. There have been conflicting results regarding the role of other AhR ligands 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) and 6-formylindolo [3,2-b]carbazole (FICZ) in modifying regulatory T cell populations (Treg) or T helper (Th)17 differentiation, and the effects of Phe have been understudied. We hypothesized that different chemical entities of PAH induce Treg to become either Th2 or Th17 effector T cells through epigenetic modification of FOXP3. To determine specific effects on T cell populations by phenanthrene, primary human Treg were treated with Phe, TCDD, or FICZ and assessed for function, gene expression, and phenotype. Methylation of CpG sites within the FOXP3 locus reduced FOXP3 expression, leading to impaired Treg function and conversion of Treg into a CD4(+)CD25(lo) Th2 phenotype in Phe-treated cells. Conversely, TCDD treatment led to epigenetic modification of IL-17A and conversion of Treg to Th17 T cells. These findings present a mechanism by which exposure to AhR-ligands mediates human T cell responses and begins to elucidate the relationship between environmental exposures, immune modulation, and initiation of human disease.
View details for DOI 10.1155/2013/967029
View details for PubMedID 23533402
Identification of human NK cells that are deficient for signaling adaptor FcR gamma and specialized for antibody-dependent immune functions
2012; 24 (12): 793-802
NK cells respond to tumor and virus-infected cells directly through several activation receptors, including natural cytotoxicity receptors, or indirectly through the activating Fc receptor CD16 for antibody-coated cells. Triggering of NK-cell effector functions through these receptors depends on physically associated transmembrane signaling adaptors, such as FcR? (also known as Fc?RI?) and CD3?, both of which have been traditionally believed to be expressed by all mature NK cells. However, we have identified a distinct subset of human NK cells that are deficient for FcR? expression but express normal levels of CD3?. FcR?-deficient NK cells were readily detectable in about one-third of the healthy individuals examined. The deficiency was confined to the CD56(dim) population and was due to low FcR? mRNA. FcR?-deficient NK cells displayed dramatically reduced expression of the natural cytotoxicity receptors NKp46 and NKp30 but still expressed substantial levels of CD16. Compared to FcR?-expressing NK cells, FcR?-deficient NK cells showed poor direct reactivity toward tumor targets as measured by cytokine production and degranulation. Unexpectedly, however, FcR?-deficient NK cells exhibited significantly more robust responsiveness upon stimulation through CD16, particularly for cytokine production, compared to FcR?-expressing NK cells. Thus, our study reveals FcR?-deficient NK cells as a novel subset of human NK cells that have remarkably potent responses toward antibody-coated targets. These findings also illustrate a differential contribution of FcR? and CD3? for the expression and functional activity of their associated receptors.
View details for DOI 10.1093/intimm/dxs080
View details for Web of Science ID 000311903800006
View details for PubMedID 22962434
CD44+cells have cancer stem cell-like properties in nasopharyngeal carcinoma
INTERNATIONAL FORUM OF ALLERGY & RHINOLOGY
2012; 2 (6): 465-470
A subpopulation of cells within a tumor appears to have the exclusive ability to initiate tumors, self-renew, and differentiate. These "cancer stem cells" (CSCs) are CD44(+) in several epithelial malignancies. We examined the potential of CD44 to identify the CSC population in nasopharyngeal carcinoma (NPC).C666, an Epstein-Barr virus-positive (EBV(+) ) human NPC cell line, was stained for CD44 and sorted by fluorescence-activated cell sorting (FACS). CD44(+) and CD44(-) subpopulations were evaluated for (1) proliferative potential, (2) ability to differentiate, (3) expression of markers of epithelial-to-mesenchymal transition (EMT) and EBV genes, and (4) the ability to initiate tumors in vivo. Immunocompromised mice were injected with CD44(+) and CD44(-) populations to assess the tumor-initiating capacity. Immunohistochemistry for CD44 was performed on an 87-patient tissue microarray (TMA), and clinical correlations were examined.Heterogeneous expression of CD44 was seen among C666 cells. CD44(+) cells differentiated into CD44(-) cells, indicating a hierarchical relationship. Further, CD44(+) cells exhibited a more robust tumor-initiating capacity in the xenograft model. However, no differences were seen in proliferation rates in vitro, EBV gene expression, or expression of EMT markers between CD44(+) and CD44(-) subsets. Patient tumors were heterogeneous for CD44 staining, and a trend toward an association between CD44 expression and clinical outcome was observed.NPC contains a CD44(+) subpopulation with features consistent with CSCs. There was a trend toward an association between CD44 expression within NPC tumors and decreased time to local failure/relapse in patients.
View details for DOI 10.1002/alr.21068
View details for Web of Science ID 000312142200006
View details for PubMedID 22887934
The manipulation of natural killer cells to target tumor sites using magnetic nanoparticles
2012; 33 (22): 5584-5592
The present work demonstrates that Cy5.5 conjugated Fe(3)O(4)/SiO(2) core/shell nanoparticles could allow us to control movement of human natural killer cells (NK-92MI) by an external magnetic field. Required concentration of the nanoparticles for the cell manipulation is as low as ~20 ?g Fe/mL. However, the relative ratio of the nanoparticles loaded NK-92MI cells infiltrated into the target tumor site is enhanced by 17-fold by applying magnetic field and their killing activity is still maintained as same as the NK-92MI cells without the nanoparticles. This approach allows us to open alternative clinical treatment with reduced toxicity of the nanoparticles and enhanced infiltration of immunology to the target site.
View details for DOI 10.1016/j.biomaterials.2012.04.041
View details for Web of Science ID 000305366500010
View details for PubMedID 22575830
Effect of stimulation of natural killer cells with an anti-CD137 mAb on the efficacy of trastuzumab, cetuximab, and rituximab
AMER SOC CLINICAL ONCOLOGY. 2012
View details for Web of Science ID 000318009801791
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
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 SIRP?, 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 Web of Science ID 000303249100065
View details for PubMedID 22451913
Targeted endoscopic salvage nasopharyngectomy for recurrent nasopharyngeal carcinoma
INTERNATIONAL FORUM OF ALLERGY & RHINOLOGY
2012; 2 (2): 166-173
Despite modern radiotherapy and open surgical techniques, treatment of recurrent nasopharyngeal carcinoma (NPC) remains challenging, with substantial morbidity involved. Targeted endoscopic nasopharyngectomy was evaluated as a viable oncologic alternative to open nasopharyngectomy or radiation for recurrent NPC.Thirteen patients who underwent endoscopic nasopharyngectomy for recurrent NPC between August 2005 and August 2010 were retrospectively reviewed. Average age at surgery was 55.7 years, with mean follow-up period 24.2 months. Two-year disease-free survival, 2-year overall survival, margin status, and complication rate were measured.Including resections for subsequent recurrences, 19 endoscopic procedures were performed with curative intent. Mean operating room (OR) time was 278 minutes, mean estimated blood loss was 197 mL, and mean length of hospitalization was 1.0 days. Negative margins were obtained in 78.9% of procedures: positive margins involved the parapharyngeal space, oropharynx, fossa of Rosenmuller, and infratemporal fossa. Stereotactic radiation was given postoperatively for localized positive margins. Four patients required repeat endoscopic nasopharyngectomy for re-recurrence, despite having their margins cleared or controlled with adjuvant treatment. Two-year local disease-free and overall survival rates were 69.2% and 100.0%, respectively. The overall minor complication rate was 52.6%, with no major complications.Targeted endoscopic nasopharyngectomy is beneficial in locally recurrent NPC, with favorable morbidity and complication rates. Endoscopic surveillance and serial imaging together facilitate the early identification of re-recurrences, which often may be treated with additional directed resection. Postoperative stereotactic radiation may serve as an appropriate adjunct modality for disease control at positive margins.
View details for DOI 10.1002/alr.20111
View details for Web of Science ID 000308926000015
View details for PubMedID 22170783
ERK1/2 Regulation of CD44 Modulates Oral Cancer Aggressiveness
2012; 72 (1): 365-374
Carcinogen-induced oral cavity squamous cell carcinoma (OSCC) incurs significant morbidity and mortality and constitutes a global health challenge. To gain further insight into this disease, we generated cell line models from 7,12-dimethylbenz(a)anthracene-induced murine primary OSCC capable of tumor formation upon transplantation into immunocompetent wild-type mice. Whereas several cell lines grew rapidly and were capable of metastasis, some grew slowly and did not metastasize. Aggressively growing cell lines displayed ERK1/2 activation, which stimulated expression of CD44, a marker associated with epithelial to mesenchymal transition and putative cancer stem cells. MEK (MAP/ERK kinase) inhibition upstream of ERK1/2 decreased CD44 expression and promoter activity and reduced cell migration and invasion. Conversely, MEK1 activation enhanced CD44 expression and promoter activity, whereas CD44 attenuation reduced in vitro migration and in vivo tumor formation. Extending these findings to freshly resected human OSCC, we confirmed a strict relationship between ERK1/2 phosphorylation and CD44 expression. In summary, our findings identify CD44 as a critical target of ERK1/2 in promoting tumor aggressiveness and offer a preclinical proof-of-concept to target this pathway as a strategy to treat head and neck cancer.
View details for DOI 10.1158/0008-5472.CAN-11-1831
View details for Web of Science ID 000298755600036
View details for PubMedID 22086849
- A cisplatin-resistant subpopulation of mesenchymal-like cells in head and neck squamous cell carcinoma CELL CYCLE 2011; 10 (17): 2834-2835
Distal-less homeobox transcription factors regulate development and maturation of natural killer cells
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2008; 105 (31): 10877-10882
Natural killer (NK) cells constitute a subpopulation of lymphocytes that develop from precursors in the bone marrow (BM), but the transcriptional regulation of their development and maturation is only beginning to be understood, in part due to their relatively rare abundance, especially of developmental subsets. Using a mouse model in which NK cells are arrested at an immature stage of development, and a gene expression profiling approach, we uncovered transient normal NK cell expression of a homeobox transcription factor (TF) family, called Distal-less (Dlx), which had been primarily implicated in murine CNS, craniofacial, limb, and skin development. Our studies demonstrate that Dlx1, Dlx2, and Dlx3 are transiently expressed in immature Mac-1(lo) NK cells within the BM, with Dlx3 being the predominantly expressed member. These genes are expressed in a temporally regulated pattern with overlapping waves of expression, and they display functional redundancy. Expression is extinguished in fully mature splenic NK cells, and persistent expression of Dlx genes leads to functionally immature NK cells arrested at the Mac-1(lo) stage. Whereas conventional splenic NK cells develop but are arrested at an immature stage, there appears to be a complete failure to develop CD127(+) thymic NK cells when Dlx genes are persistently expressed. We also observed that T and B cells fail to develop in the context of persistent Dlx1 expression. Thus, these studies indicate that Dlx TFs play a functional role in lymphocyte development.
View details for DOI 10.1073/pnas.0805205105
View details for Web of Science ID 000258308500047
View details for PubMedID 18664585
Temporal Relationship Between Antitumor Necrosis Factor-alpha Antibody Therapy and Recrudescence of Head and Neck Squamous Cell Carcinoma
2008; 118 (3): 450-452
Tumor necrosis factor (TNF)-alpha inhibitors have been used effectively to treat rheumatoid arthritis and inflammatory bowel disease. Although the role of TNF-alpha in tumor development is not well understood, an increased risk of malignancies with anti-TNF-alpha therapy has been suggested. We report an instructive case of a patient, treated for Crohn's disease with infliximab, who presented with a neck abscess diagnosed to be head and neck squamous cell carcinoma. The patient's clinical course illustrates a temporal relationship between reappearance of his cancer after a complete response to therapy and the resumption of infliximab for worsening Crohn's disease.
View details for DOI 10.1097/MLG.0b013e31815abf4c
View details for Web of Science ID 000260661800012
View details for PubMedID 18090867
HLA alleles determine differences in human natural killer cell responsiveness and potency
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2008; 105 (8): 3053-3058
Epidemiological studies have associated certain human disease outcomes with particular killer cell Ig-like receptor (KIR) and HLA genotypes. However, the functional explanation for these associations is poorly understood, because the KIRs were initially described as natural killer (NK) cell inhibitory receptors with specificity for HLA molecules on their cellular targets. Yet resolution of infections is often associated with genotypic pairing of inhibitory KIRs with their cognate HLA ligands. Recent studies in mice indicate a second role for MHC-specific inhibitory receptors, i.e., self-MHC recognition confers functional competence on the NK cell to be triggered through their activation receptors, a process termed licensing. As a result, licensed NK cells with self-MHC-specific receptors are more readily activated as compared with unlicensed NK cells without self-MHC-specific receptors. Such results predict that human NK cells may undergo a similar process. Here, we examined the human NK cell subset expressing KIR3DL1, the only known KIR specific for HLA-Bw4 alleles. The KIR3DL1(+) subset in normal donors with two HLA-B-Bw4 genes displayed increased responsiveness to tumor stimulation compared with the KIR3DL1(+) subset from individuals with only one or no Bw4 genes. By contrast, NK cells lacking KIR3DL1 showed no differences. Therefore, these data indicate that particular KIR and HLA alleles are associated with more responsive NK cells, strongly suggesting that human NK cells are also subjected to NK cell licensing, and providing a potential functional explanation for the influence of KIR and HLA genes in disease as well as interindividual differences in NK cell potency.
View details for DOI 10.1073/pnas.0712229105
View details for Web of Science ID 000253567900055
View details for PubMedID 18287063
Spontaneous regression of cutaneous head and neck melanoma: Implications for the immunologic control of neoplasia
HEAD AND NECK-JOURNAL FOR THE SCIENCES AND SPECIALTIES OF THE HEAD AND NECK
2008; 30 (2): 267-272
Spontaneous regression of cancer in the head and neck is a rare event. Moreover, there are rare reported cases of spontaneous regression of primary head and neck melanoma with accompanying immunohistochemical analysis of the tumor.We used detailed preoperative and postoperative pathologic examination of a lesion in the right supraclavicular region.Pathologic examination of the initial specimen identified a melanoma of superficial spreading type with vertical growth and a thickness of 1.8 mm. The excised specimen demonstrated a complete regression of the melanoma with a florid host inflammatory response predominantly composed of a histiocytic reaction.The case presented illustrates histopathologic findings occurring in a head and neck melanoma as it is undergoing spontaneous regression. These findings point to a potentially critical role for histiocytes in effecting tumor elimination. Pathologic analysis of spontaneous head and neck melanoma regression will ultimately facilitate an improved understanding of naturally-occurring tumor elimination.
View details for DOI 10.1002/hed.20701
View details for Web of Science ID 000252945800017
View details for PubMedID 17657794
Mycotic pseudoaneurysm of the internal maxillary artery - Case report and review of the literature
ARCHIVES OF OTOLARYNGOLOGY-HEAD & NECK SURGERY
2007; 133 (4): 402-406
Pseudoaneurysms of the internal maxillary artery are rare entities that are most commonly caused by trauma. Herein we report a novel case of an internal maxillary artery pseudoaneurysm of infectious etiology and discuss the diagnosis and treatment of this disease.
View details for Web of Science ID 000245628600015
View details for PubMedID 17438257
Arrested natural killer cell development associated with transgene insertion into the Atf2 locus
2006; 107 (3): 1024-1030
Natural killer (NK) cell development in the bone marrow is not fully understood. Following lineage commitment, these cells appear to advance through a series of developmental stages that are beginning to be characterized. We previously reported a selective deficiency of NK cells in a C57BL/6 mouse with a transgenic construct consisting of the cDNA for the Ly49A major histocompatibility complex (MHC) class 1-specific inhibitory receptor driven by the granzyme A gene. This mouse has few NK cells in peripheral tissues with relative preservation of other immune cells, including T and B cells. Herein we demonstrate that these mice have an accumulation of NK cells with an immature phenotype in the bone marrow, consistent with a block at a previously proposed stage in normal NK-cell development. The phenotype is associated with transgenic insertion into Atf2, the gene for the basic leucine zipper (bZIP) transcription factor family member ATF-2. Although analysis of Atf2-null NK cells shows no defect, the transgenic mice express abnormal truncated Atf2 transcripts that may mediate a repressor effect because ATF2 can heterodimerize with other bZIP molecules. The defect is cell intrinsic, suggesting that certain bZIP molecules play significant roles in NK-cell development.
View details for DOI 10.1182/blood-2005-04-1493
View details for Web of Science ID 000234991600036
View details for PubMedID 16223777
Inhibition of nuclear factor-kappa B and target genes during combined therapy with proteasome inhibitor bortezomib and reirradiation in patients with recurrent head-and-neck squamous cell carcinoma
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS
2005; 63 (5): 1400-1412
To examine the effects the proteasome inhibitor bortezomib (VELCADE) on transcription factor nuclear factor-kappaB (NF-kappaB) and target genes and the feasibility of combination therapy with reirradiation in patients with recurrent head-and-neck squamous cell carcinoma (HNSCC).The tolerability and response to bortezomib 0.6 mg/m2 and 0.9 mg/m2 given twice weekly concurrent with daily reirradiation to 50-70 Gy was explored. Blood proteasome inhibition and NF-kappaB-modulated cytokines and factors were measured. Proteasome inhibition, nuclear localization of NF-kappaB phospho-p65, apoptosis, and expression of NF-kappaB-modulated mRNAs were compared in serial biopsies from accessible tumors.The maximally tolerated dose was exceeded, and study was limited to 7 and 2 patients, respectively, given bortezomib 0.6 mg/m2 and 0.9 mg/m2/dose with reirradiation. Grade 3 hypotension and hyponatremia were dose limiting. Mucositis was Grade 3 or less and was delayed. The mean blood proteasome inhibition at 1, 24, and 48 h after 0.6 mg/m2 was 32%, 16%, and 7% and after 0.9 mg/m2 was 56%, 26%, and 14%, respectively. Differences in proteasome and NF-kappaB activity, apoptosis, and expression of NF-kappaB-modulated cell cycle, apoptosis, and angiogenesis factor mRNAs were detected in 2 patients with minor tumor reductions and in serum NF-kappaB-modulated cytokines in 1 patient with a major tumor reduction.In combination with reirradiation, the maximally tolerated dose of bortezomib was exceeded at a dose of 0.6 mg/m2 and the threshold of proteasome inhibition. Although this regimen with reirradiation is not feasible, bortezomib induced detectable differences in NF-kappaB localization, apoptosis, and NF-kappaB-modulated genes and cytokines in tumor and serum in association with tumor reduction, indicating that other schedules of bortezomib combined with primary radiotherapy or reirradiation may merit future investigation.
View details for DOI 10.1016/j.ijrobp.2005.05.007
View details for Web of Science ID 000233477300018
View details for PubMedID 16005577
Licensing of natural killer cells by host major histocompatibility complex class I molecules
2005; 436 (7051): 709-713
Self versus non-self discrimination is a central theme in biology from plants to vertebrates, and is particularly relevant for lymphocytes that express receptors capable of recognizing self-tissues and foreign invaders. Comprising the third largest lymphocyte population, natural killer (NK) cells recognize and kill cellular targets and produce pro-inflammatory cytokines. These potentially self-destructive effector functions can be controlled by inhibitory receptors for the polymorphic major histocompatibility complex (MHC) class I molecules that are ubiquitously expressed on target cells. However, inhibitory receptors are not uniformly expressed on NK cells, and are germline-encoded by a set of polymorphic genes that segregate independently from MHC genes. Therefore, how NK-cell self-tolerance arises in vivo is poorly understood. Here we demonstrate that NK cells acquire functional competence through 'licensing' by self-MHC molecules. Licensing involves a positive role for MHC-specific inhibitory receptors and requires the cytoplasmic inhibitory motif originally identified in effector responses. This process results in two types of self-tolerant NK cells--licensed or unlicensed--and may provide new insights for exploiting NK cells in immunotherapy. This self-tolerance mechanism may be more broadly applicable within the vertebrate immune system because related germline-encoded inhibitory receptors are widely expressed on other immune cells.
View details for DOI 10.1038/nature03847
View details for Web of Science ID 000230964500046
View details for PubMedID 16079848
Nuclear factor-kappa B is an important modulator of the altered gene expression profile and malignant phenotype in squamous cell carcinoma
2004; 64 (18): 6511-6523
We reported previously that transcription factor nuclear factor (NF)-kappaB is constitutively activated in human and murine squamous cell carcinomas (SCCs). The role of NF-kappaB in the cumulative changes in gene expression with transformation and progression of the murine SCC Pam 212 and after switching off NF-kappaB by a dominant negative inhibitor kappaB mutant (IkappaBalphaM) was explored by profiling with a 15,000-element cDNA micoarrray. Remarkably, NF-kappaB modulated the expression of >60% of the 308 genes differentially expressed between normal keratinocytes and metastatic SCCs. NF-kappaB directly or indirectly modulated expression of programs of genes functionally linked to proliferation, apoptosis, adhesion, and angiogenesis. Among these, changes in expression of cyclin D1, inhibitor of apoptosis-1, mutant Trp53, and beta-catenin detected with modulation of NF-kappaB by microarray were confirmed by Western and Northern blot. NF-kappaB DNA binding motifs were detected in the promoter of approximately 63% of genes showing increased expression and 33% of the genes showing decreased expression. The ACTACAG motif implicated in the NF-kappaB-dependent down-regulation of mRNA expression of MyoD and Sox9 was detected in the coding portion of about 15% of genes showing increased or decreased expression. Inactivation of NF-kappaB inhibited malignant phenotypic features including proliferation, cell survival, migration, angiogenesis, and tumorigenesis. These results provide evidence that NF-kappaB is an important modulator of gene expression programs that contribute to the malignant phenotype of SCC.
View details for Web of Science ID 000224089700025
View details for PubMedID 15374962
Effects of pharmacologic antagonists of epidermal growth factor receptor, PI3K and MEK signal kinases on NF-kappa B and AP-1 activation and IL-8 and VEGF expression in human head and neck squamous cell carcinoma lines
INTERNATIONAL JOURNAL OF CANCER
2002; 99 (4): 538-548
We previously reported that expression of angiogenesis factors interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF) is promoted by coactivation of transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) by interleukin-1alpha in human head and neck squamous cell carcinomas (HNSCC). However, expression of IL-1 receptor antagonist incompletely blocked reporter gene activity and cytokine expression, suggesting that other upstream signals may contribute to activation. Overexpression and autocrine activation of epidermal growth factor receptor (EGFR) is detected in 90% of HNSCC, and EGFR inhibitors have been reported to inhibit IL-8 and VEGF expression, but the intermediary signal pathways and transcription factors by which EGFR modulates proangiogenic factors is unknown. EGFR can activate the phosphotidylinositol-3 kinase (PI3K) and mitogen-activated/extracellular signal-regulated kinase (MEK) pathways, which can potentially modulate activation of NF-kappaB and AP-1, respectively. In our study, we examined the effect of EGF and antagonists of EGFR, PI3K and MEK on NF-kappaB and AP-1 activation and IL-8 and VEGF expression in HNSCC cell lines UM-SCC-9 and 11B in which EGFR is overexpressed and activated. Recombinant EGF induced EGFR phosphorylation, activation of NF-kappaB and AP-1 reporter genes and IL-8 and VEGF expression, indicating that EGFR can mediate coactivation of both transcription factors and cytokine genes in HNSCC. EGFR antagonist PD153035 and anti-EGFR antibody C225 completely inhibited EGF-induced reporter activity and cytokine expression, but only partially inhibited constitutive activity. MEK inhibitor U0126 preferentially blocked AP-1 activity and expression of both IL-8 and VEGF, while PI3K inhibitor LY-294002 or a dominant negative inhibitor-kappaB preferentially blocked NF-kappaB activation and expression of IL-8 but not VEGF. EGFR, PI3K and MEK antagonists inhibited growth of HNSCC. We conclude that antagonists of EGFR, PI3K and MEK signal pathways have inhibitory activity against EGFR-induced NF-kappaB and AP-1 activation, IL-8 and VEGF expression and growth by HNSCC. Published 2002 Wiley-Liss, Inc.
View details for DOI 10.1002/ijc.10398
View details for Web of Science ID 000175372700007
View details for PubMedID 11992543
Transcript map of the 8p23 putative tumor suppressor region
2001; 75 (1-3): 17-25
Cancers of the head and neck, prostate, liver, and bladder exhibit minimal regions of deletion within chromosomal band 8p23 that either overlap or map very close to one another. We previously refined a minimal region of deletion in squamous cell carcinomas to a 112-kb interval within 8p23. There seems to be only a single gene within this region that is expressed in normal upper aerodigestive tract epithelium. This candidate for the squamous cancer suppressor, CUB and sushi multiple domains-1 (CSMD1), extends into the minimal regions of deletions defined for the other types of cancer with 8p23 deletions. RT-PCR and EST data indicate that CSMD1 is also expressed in those organs,making this gene a candidate for a suppressor of multiple types of cancer. Both the sequence of the gene and the organization of the protein are highly conserved in the mouse.
View details for DOI 10.1006/geno.2001.6587
View details for Web of Science ID 000169795100005
View details for PubMedID 11472063
IL (interleukin)-1 alpha promotes nuclear factor-kappa B and AP-1-induced IL-8 expression, cell survival, and proliferation in head and neck squamous cell carcinomas
CLINICAL CANCER RESEARCH
2001; 7 (6): 1812-1820
Interleukin 1alpha (IL-1alpha) is an important regulatory cytokine, the release of which after an injury can induce activation of transcription factors nuclear factor (NF)kappaB and activator protein (AP-1), which promote expression of genes involved in cell survival, proliferation, and angiogenesis. IL-1alpha is expressed autonomously by head and neck squamous cell carcinomas (HNSCCs) and a variety of other cancers, raising the possibility that IL-1alpha may serve as an autocrine factor that stimulates the activation of prosurvival transcription factors and target genes in cancer. In this study, we examined the role of IL-1alpha in the activation of NFkappaB and AP-1, the expression of proangiogenic cytokine IL-8, and in the survival and proliferation of HNSCC cell lines. HNSCCs were found to secrete and respond to functional IL-1alpha, in that culture supernatant from a high IL-1alpha-secreting line, UM-SCC-11B, could induce secretion of cytokine IL-8 by a low IL-1alpha-secreting line, UM-SCC-9; and the induction of IL-8 secretion could be blocked by the anti-IL-1alpha-neutralizing antibody or the IL-1 receptor antagonist (IL-1RA). Furthermore, IL-1alpha could induce the expression of IL-8 through an autocrine mechanism, in that transfection of UM-SCC-9 cells with a plasmid encoding IL-1alpha resulted in the increased coexpression of IL-1alpha and IL-8; whereas transfection with a plasmid encoding IL-1RA lacking the secretory leader sequence led to the decreased coexpression of IL-1alpha and IL-8. IL-1alpha was found to induce coexpression of IL-8 through the activation of NFkappaB and AP-1, in that mutation of the NFkappaB site within the IL-8 promoter abolished autocrine- and recombinant IL-1alpha-induced IL-8 reporter gene activity, whereas mutation in AP-1 partially decreased IL-8 reporter gene activity in UM-SCC-9 cells. Intracellular expression of IL-1RA decreased NFkappaB reporter gene activity, indicating that endogenously expressed IL-1alpha contributes to constitutive NFkappaB activation in this HNSCC line. Expression of IL-1alpha affected survival of UM-SCC-9, inasmuch as transfection of cells with plasmid encoding IL-1alpha or IL-1RA led to the increased or decreased survival of cells cotransfected with a beta-galactosidase reporter gene, respectively. IL-1alpha was also found to promote the increased growth of UM-SCC-9 cells in vitro. We demonstrate that exogenous and endogenous IL-1alpha contributes to the transcriptional activation of NFkappaB and AP-1, to the expression of IL-8, and to cell survival and the growth of HNSCC in vitro.
View details for Web of Science ID 000169310600045
View details for PubMedID 11410524
Novel proteasome inhibitor PS-341 inhibits activation of nuclear factor-kappa B, cell survival, tumor growth, and angiogenesis in squamous cell carcinoma
CLINICAL CANCER RESEARCH
2001; 7 (5): 1419-1428
We have shown that activation of nuclear factor-kappa B (NF-kappa B) promotes cell survival and expression of cytokines such as growth-regulated oncogene-alpha, which can modulate angiogenesis, growth, and metastasis of squamous cell carcinoma (SCC). Activation of NF-kappa B and cytoprotective genes in cancer may result from signal-induced phosphorylation and proteasome-dependent degradation of inhibitor-kappa B. In this study, we examined the effects of the novel proteasome inhibitor PS-341 on activation of NF-kappa B and cell survival, growth, and angiogenesis in murine and human SCC cell lines. PS-341 inhibited activation of NF-kappa B DNA binding and functional reporter activity at concentrations between 10(-8) and 10(-7) M. Cytotoxicity was observed at 10(-7) M in four murine and two human SCC lines, and followed early cleavage of poly(ADP-ribose) polymerase, a marker of caspase-mediated apoptosis. In vivo, PS-341 inhibited growth of murine and human SCC in mice at doses of 1--2 mg/kg given three times weekly, and dose-limiting toxicity was encountered at 2 mg/kg. Tumor growth inhibition was associated with a marked decrease in vessel density. PS-341 inhibited expression of the proangiogenic cytokines growth-regulated oncogene-alpha and vascular endothelial growth factor by SCC in the range at which PS-341 inhibits NF-kappa B. We conclude that PS-341 inhibits activation of NF-kappa B pathway components related to cell survival, tumor growth, and angiogenesis in SCC.
View details for Web of Science ID 000168768500044
View details for PubMedID 11350913
Coexpression of proangiogenic factors IL-8 and VEGF by human head and neck squamous cell carcinoma involves coactivation by MEK-MAPK and IKK-NF-kappa B signal pathways
CLINICAL CANCER RESEARCH
2001; 7 (2): 435-442
Interleukin 8 (IL-8) and vascular endothelial growth factor (VEGF) promote tumor angiogenesis, growth, and metastasis and are coexpressed by human head and neck squamous cell carcinomas (HNSCCs) and a variety of other cancers. The promoters of the IL-8 and VEGF genes contain different recognition sites for transcription factors nuclear factor (NF)-kappaB and activator protein-1 (AP-1), which we showed previously are coactivated in HNSCCs. NF-kappaB and AP-1 may be modulated by the inhibitor kappaB kinase (IKK) and mitogen-activated protein kinase (MAPK) signal pathways, but the contribution of these pathways to expression of IL-8 and VEGF and as potential targets for antiangiogenesis therapy in HNSCC is not known. In this study, we examined the effects of modulation of the MAPK and IKK pathways on expression of IL-8 and VEGF by UM-SCC-9 and UM-SCC-11B cell lines. Interruption of IKK-mediated activation of NF-kappaB by expression of an inhibitor kappaB alpha mutant (IkappaB alphaM) in UM-SCC-9 cells resulted in partial inhibition of expression of IL-8 but not VEGF. Analysis of possible alternative pathways for induction of these genes revealed activation of the MAPK extracellular signal-regulated kinase (ERK1/2) in cell lines UM-SCC-9 and UM-SCC-11B. Basal and tumor necrosis factor-alpha-inducible phosphorylation of ERK1/2 and secretion of IL-8 and VEGF could be specifically inhibited by a MEK inhibitor, U0126. Expression of IL-8 and VEGF in the cell lines was associated with coactivation of both NF-kappaB and AP-1, and U0126 inhibited both NF-kappaB and AP-1 reporter activity in UM-SCC-9 and UM-SCC-11B cells. The ERK pathway appears to contribute to expression of IL-8 and VEGF and transactivation of NF-kappaB as well as AP-1 in HNSCC. Combined inhibition of both MAPK and IKK pathways may be needed for suppression of the signal transduction mechanism(s) regulating VEGF and IL-8 secretion and angiogenesis by human HNSCC.
View details for Web of Science ID 000167160200031
View details for PubMedID 11234901
Concurrent paclitaxel and radiation in the treatment of locally advanced head and neck cancer
JOURNAL OF CLINICAL ONCOLOGY
2001; 19 (3): 800-811
To determine the feasibility of an organ preservation regimen consisting of infusional paclitaxel administered concurrently with radiotherapy to patients with locally advanced head and neck squamous cell carcinoma (HNSCC).Thirty-three previously untreated patients with stage III or IV tumors were enrolled onto the study. Paclitaxel was administered as a 120-hour continuous infusion every 3 weeks during the course of radiation therapy. Sixteen patients received a paclitaxel dose of 105 mg/m(2), and 17 patients received 120 mg/m(2). Radiation was delivered in a standard format at 1.8 Gy/d to a total dose of 70.2 to 72 Gy.Three months after therapy, a 76% complete response (CR) at the primary site and a 70% overall CR was achieved. At 36 months, locoregional control was 55.7%, overall survival was 57.8%, and disease-free survival was 51.1%. The median survival duration for all 33 patients was greater than 50 months at the time of this report. Local toxicities including mucositis, dysphagia, and skin reactions were severe but tolerable. All patients retained functional speech, and all but four patients were swallowing food 3 months after treatment. Steady-state plasma concentrations for paclitaxel were not achieved during a 120-hour infusion, suggesting a nonlinear process. Tumor volume quantified by pretreatment computerized tomography imaging was associated with likelihood of response and survival.Paclitaxel administered as a 120-hour continuous infusion in combination with radiotherapy is a feasible and promising treatment for patients with advanced HNSCC.
View details for Web of Science ID 000166803100027
View details for PubMedID 11157034
Homozygous deletions define a region of 8p23.2 containing a putative tumor suppressor gene
1999; 62 (2): 184-188
Loss of heterozygosity at microsatellite loci in chromosomal band 8p23.2 is a frequent event in squamous cell carcinomas of the head and neck, suggesting that this region contains a putative tumor suppressor. Allelic loss studies on laryngeal and oral/oropharyngeal tumors have restricted the size of this region to approximately 1 cM. A similar pattern of deletions is also observed in prostatic and ovarian adenocarcinomas. As part of an effort to identify this gene by positional cloning, we developed a physical contig consisting of 12 overlapping bacterial artificial chromosome (BAC) clones spanning this interval. We developed sequence-tagged sites from the ends of these BACs and used them, along with seven microsatellite loci, to detect and map homozygous deletions in four head and neck squamous cancer cell lines. Our mapping analysis further restricted the consensus minimal region of deletion to a <191-kb interval.
View details for Web of Science ID 000084825100008
View details for PubMedID 10610711
Multiple regions of deletion on chromosome arm 13q in head-and-neck squamous-cell carcinoma
INTERNATIONAL JOURNAL OF CANCER
1999; 84 (5): 453-457
Several lines of evidence suggest that the progression of head-and-neck squamous-cell carcinoma (HNSCC) involves inactivation of at least one and possibly several tumor-suppressor genes on the long arm of chromosome 13. The fact that neither Rb1 nor BRCA2 appears to be inactivated in the majority of head-and-neck cancers suggests that novel tumor-suppressor genes are involved. We have used microsatellite repeat polymorphisms and PCR to detect several distinct minimal regions of deletion on 13q in supraglottic and oral squamous-cell carcinomas. One region maps to 13q34, the second to 13q14.3 and a potential third region, not reported in previous studies, maps to 13q12.1. Overall, 69% of the 145 tumors examined demonstrated allelic loss at one or more loci on 13q. We investigated whether a novel suppressor candidate mapping to 13q14. 3-q21, leukemia-associated gene 1, might also be involved in the progression of squamous-cell carcinomas. Multiplexed PCR revealed homozygous deletion of leu1 in one oral cavity tumor. This suggests that this gene or one nearby may be the actual target of deletions in this region of the chromosome arm.
View details for Web of Science ID 000082967100001
View details for PubMedID 10502719
Constitutive activation of transcription factors NF-kappa B, AP-1, and NF-IL6 in human head and neck squamous cell carcinoma cell lines that express pro-inflammatory and pro-angiogenic cytokines
1999; 26 (2): 119-129
We previously reported that human head and neck squamous cell carcinomas (HNSCCs) express the pro-inflammatory and pro-angiogenic cytokines interleukin (IL)-1alpha, IL-6, IL-8, and granulocyte-macrophage colony-stimulating factor in vitro and in vivo. The promoter region of the genes encoding these cytokines include binding sites for the transcription factors nuclear factor (NF) kappaB/Rel A, activator protein-1 (AP-1), and CCAAT enhancer-binding protein beta (C/EBPbeta, or NF-IL6), which have been reported to contribute to activation of these cytokine genes. In the study presented here, we examined the activation, composition, and function of these transcription factors in HNSCC cell lines that express pro-inflammatory cytokines, by using electrophoretic mobility shift and reporter-gene assays. Constitutive activation of NF-kappaB, AP-1, and NF-IL6 DNA-binding proteins was detected. Supershift analysis with antibodies specific for NF-kappaB, AP-1, and NF-IL6 binding proteins showed that the NF-kappaB-binding protein included p65/Rel A and p50; AP-1 activity included c-jun, junB, junD, and Fra-1; and NF-IL6 included C/EBPbeta. Mutational analysis of the NF-kappaB, AP-1, and NF-IL6 sites in the IL-8 promoter region showed that NF-kappaB and AP-1 sites contributed to constitutive IL-8 reporter activity in HNSCC. HNSCC lines that exhibited increased IL-8 secretion relative to simian virus 40-immortalized and primary keratinocyte cell lines also demonstrated a concordant increase in NF-kappaB reporter activity relative to nonmalignant keratinocytes. We concluded that the early transcription factors NF-kappaB, AP-1, and NF-IL6 are constitutively activated in human HNSCC cell lines and that NF-kappaB and AP-1 promote expression of the pro-inflammatory and pro-angiogenic cytokine IL-8 in HNSCC. The demonstration of the activation of these transcription factors will be helpful in defining the identity and role of these and other early gene products that contribute to pathogenesis of the malignant phenotype in HNSCC and in defining potential targets for pharmacologic and molecular therapy of HNSCC. Mol. Carcinog. 26:119-129, 1999. Published 1999 Wiley-Liss, Inc.
View details for Web of Science ID 000082978600006
View details for PubMedID 10506755
Localization of a putative tumor suppressor gene in the sub-telomeric region of chromosome 8p
1999; 18 (16): 2651-2655
Several regions of chromosome arm 8p are frequently deleted in a variety of human malignancies including those of the prostate, head and neck, lung, and colon, suggesting that there is more than one tumor suppressor gene on this chromosome arm. Both laryngeal and oral squamous cell carcinomas exhibit three distinct and nonoverlapping regions of deletion on 8p. We have further refined the localization of the putative suppressor in 8p23 by using eight microsatellite loci to create a high resolution deletion map of 150 squamous cell carcinomas of the larynx and oral cavity. These new data demonstrate that there are two distinct classes of deletion within this relatively small region of the chromosome and suggest two possible locations for the gene within the D8S264 to D8S1788 interval. We also determined that there is little difference between the allelic loss frequencies of microsatellites mapping near the telomeric ends of other chromosome arms and loci mapping to more centromere proximal regions of the same arm. These data suggest that the high allelic loss frequencies seen at 8p23 loci are not the result of a generalized instability of chromosome ends and are instead consistent with the activation of a specific suppressor gene.
View details for Web of Science ID 000079907100013
View details for PubMedID 10353609
Clinical correlations with allelotype in supraglottic squamous cancer
OTOLARYNGOLOGY-HEAD AND NECK SURGERY
1998; 118 (3): 363-370
Frequent allelic loss at a genetically polymorphic locus in tumors is an established marker for the presence of a tumor suppressor gene in the neighboring chromosomal region. This technique can be used to identify novel tumor suppressor genes and to monitor their status before the cloning of the gene itself. We have used the polymerase chain reaction and microsatellite loci on all 39 nonacrocentric autosomal chromosomal arms to identify sites of frequent allelic loss in squamous cell carcinomas of the supraglottic larynx. Our allelotype identified seven chromosomal arms (3p, 5q, 8p, 9p, 9q, 13q, and 17p) likely to contain tumor suppressor genes frequently inactivated during squamous tumorigenesis in the larynx. We tested for associations between allelic losses on these chromosomal arms and the clinical and histopathologic features of these tumors. There were no correlations with either T or N classifications. Allelic loss on chromosomal arm 13q is significantly associated with a number of histopathologic features characteristic of poorly differentiated or histologically aggressive tumors. Allelic loss on this arm also exhibits statistical trends toward association with early tumor recurrence and poor survival. The association with survival was substantiated by a multivariate Cox proportional hazards model.
View details for Web of Science ID 000072520700014
View details for PubMedID 9527118
Chromosome 8 allelic loss and the outcome of patients with squamous cell carcinoma of the supraglottic larynx
JOURNAL OF THE NATIONAL CANCER INSTITUTE
1996; 88 (22): 1676-1682
Loss of genetic heterogeneity (allelic loss or loss of heterozygosity) on chromosome arm 8p is frequent in squamous cell carcinomas of the head and neck and has been associated with poor prognosis. We have previously demonstrated that there are three minimal regions of allelic loss on this chromosome arm. The location of each region is marked by a microsatellite locus: D8S264 (8p23), D8S552 (8p23-p22), and D8S133 (8p21). These findings imply the existence of at least three putative tumor suppressor genes on this chromosome arm that may become inactivated during the progression of squamous cell carcinoma.We used allelic loss data from these three loci to determine if inactivation of these putative suppressors is associated with poor prognosis for patients with squamous cell carcinoma of the supraglottic larynx. We also used multivariate statistics to compare the prognostic power of allelic loss at these genetic markers with that of demographic, clinical, and histopathologic parameters.We examined the D8S264, D8S552, and D8S133 microsatellites in tumors from a retrospective population of 59 patients. All patients had histologically confirmed squamous cell carcinoma of the supraglottic larynx and had been treated surgically. DNA was extracted from matched sets of normal and microdissected tumor tissue and used for polymerase chain reaction amplification of the microsatellite markers. Reaction products were separated by denaturing gel electrophoresis and visualized by autoradiography. Patient data were obtained from the original pathology report and from the tumor registry of the Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO. Histopathologic data were obtained by reviewing the portion of the resection specimen used for DNA extraction. Parameters whose association with reduced disease-free interval and reduced disease-specific survival was statistically significant were identified by use of the Kaplan-Meier method and the logrank statistic. Multivariate Cox proportional hazards models were used to identify independent predictors of poor prognosis. All statistical tests were two-sided.In this patient population, allelic loss at the D8S264 locus was associated with both shorter disease-free interval (logrank P = .028) and reduced disease-specific survival (logrank P = .004). Allelic loss at the next most centromeric locus, D8S552, had a statistically significant association with only reduced disease-specific survival (logrank P = .034), whereas allelic loss at the most centromeric region, D8S133, showed no statistically significant association with reductions in either interval. Multivariate Cox models suggested that D8S264 was the only 8p marker of the three microsatellites with a statistically significant and independent association with shortened disease-free interval (relative risk [RR] = 3.38; P = .0107) and reduced disease-specific survival (RR = 3.41; P = .0105).Allelic loss in the p23 region of chromosome 8 appears to be a statistically significant, independent predictor of poor prognosis in patients with supraglottic squamous cell carcinoma.
View details for Web of Science ID A1996VU79300018
View details for PubMedID 8931613
Evidence for multiple tumor suppressor genes on chromosome arm 8p in supraglottic laryngeal cancer
GENES CHROMOSOMES & CANCER
1996; 16 (3): 164-169
Loss of heterozygosity studies of a variety of human tumors suggest that there are several tumor suppressor genes on chromosome arm 8p. To localize these genes more precisely, we utilized polymerase chain reaction amplification of microsatellite repeat polymorphisms and examined the allelic loss patterns of 17 marker loci on 8p in a population of 59 supraglottic laryngeal squamous cell carcinomas. Twenty-three of these tumors (39%) had an allelic loss at one or more of the markers examined. The allelic loss patterns of these tumors support the presence of at least three different tumor suppressor genes on 8p: one in 8p23, one in 8p22-23, and another in 8p21.
View details for Web of Science ID A1996UV00200002
View details for PubMedID 8814448
CELL-CYCLE OSCILLATION OF PHOSPHATASE INHIBITOR-2 IN RAT FIBROBLASTS COINCIDENT WITH P34CDC2 RESTRICTION
1990; 344 (6261): 74-78
Attention has focused on the regulation of the eucaryotic cell division cycle since the protein kinase p34cdc2 was identified as a key enzyme in mitotic induction. The level of this kinase remains constant throughout the cell cycle but its activity alters, particularly before M phase. Although the factors regulating cdc2 activity are still unknown, there is increasing evidence that it is influenced by p34cdc2 dephosphorylation. Protein phosphatase inhibitor-2 (I2) is a specific inhibitor of phosphatase type-1, which with type-2A is one of the two principal Ser(P) and Thr(P) phosphatases. Here we show that the level of I2, assayed by immunofluorescence staining, activity measurements, western immunoblotting and metabolic labelling, oscillates during the cell cycle in rat fibroblasts, peaking at S phase and mitosis. Moreover, when we inhibited I2 in vivo by microinjection of anti-I2 antibodies in S-phase cells, the pseudo-mitotic cellular response to injected p34cdc2 was restored, indicating that I2 might have a role in the modulation of p34cdc2 activity.
View details for Web of Science ID A1990CQ97200067
View details for PubMedID 2406614