Multi-kinase compensation rescues EGFR knockout in a cell line model of head and neck squamous cell carcinoma.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is a debilitating disease with poor survival rates. While the epidermal growth factor receptor (EGFR)-targeting antibody Cetuximab is approved for treatment, responses are limited and the molecular mechanisms driving resistance remain incompletely understood. METHODS: To better understand how cells survive without EGFR activity, we developed an EGFR knockout derivative of the UM-SCC-92 cell line using CRISPR/Cas9 technology. We then characterized changes to the transcriptome with RNAseq and changes in response to kinase inhibitors with resazurin cell viability assays. Finally, we tested if inhibitors with activity in the EGFR knockout model also had synergistic activity in combination with EGFR inhibitors in either wild type UM-SCC-92 cells or a known Cetuximab-resistant model. RESULTS: Functional and molecular analysis showed that knockout cells had decreased cell proliferation, upregulation of FGFR1 expression, and an enhanced mesenchymal phenotype. In fact, expression of common EMT genes including VIM, SNAIL1, ZEB1 and TWIST1 were all upregulated in the EGFR knockout. Surprisingly, EGFR knockout cells were resistant to FGFR inhibitor monotherapies, but sensitive to combinations of FGFR and either XIAP or IGF-1R inhibitors. Accordingly, both wild type UM-SCC-92 and Cetuximab-resistant UM-SCC-104 cells with were sensitive to combined inhibition of EGFR, FGFR and either XIAP or IGF-1R. CONCLUSIONS: These data offer insights into EGFR inhibitor resistance and show that resistance to EGFR knockout likely occurs through a complex network of kinases. Future studies of cetuximab-resistant HNSCC tumors are warranted to determine if this EMT phenotype and/or multi-kinase resistance is observed in patients.

Tumor immune microenvironment alterations using induction cetuximab in a phase II trial of deintensified therapy for p16-positive oropharynx cancer.

BACKGROUND: We sought to characterize early changes in CD8+ tumor-infiltrating lymphocytes and tumor transcriptomes after induction cetuximab in a cohort with p16-positive oropharyngeal cancer on a phase II clinical de-escalation trial. METHODS: Tumor biopsies were obtained before and 1 week after a single cetuximab loading dose in eight patients enrolled in a phase II trial of cetuximab and radiotherapy. Changes in CD8+ tumor-infiltrating lymphocytes and transcriptomes were assessed. RESULTS: One week after cetuximab, five patients (62.5%) had an increase in CD8+ cell infiltration with a median (range) fold change of +5.8 (2.5-15.8). Three (37.5%) had unchanged CD8+ cells (median [range] fold change of -0.85 [0.8-1.1]). In two patients with evaluable RNA, cetuximab induced rapid tumor transcriptome changes in cellular type 1 interferon signaling and keratinization pathways. CONCLUSIONS: Within 1 week, cetuximab induced measurable changes in pro-cytotoxic T-cell signaling and immune content.

Small molecule profiling to define synergistic EGFR inhibitor combinations in head and neck squamous cell carcinoma.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is a debilitating disease with poor survival. Although epidermal growth factor receptor (EGFR)-targeting antibody cetuximab improves survival in some settings, responses are limited suggesting that alternative approaches are needed. METHODS: We performed a high throughput drug screen to identify EGFR inhibitor-based synergistic combinations of clinically advanced inhibitors in models resistant to EGFR inhibitor monotherapies, and then performed downstream validation experiments on prioritized synergistic combinations. RESULTS: From our screen, we re-discovered known synergistic EGFR inhibitor combinations with FGFR or IGF-1R inhibitors that were broadly effective and also discovered novel synergistic combinations with XIAP inhibitor and DNMT inhibitors that were effective in only a subset of models. CONCLUSIONS: Conceptually, our data identify novel synergistic combinations that warrant evaluation in future studies, and suggest that some combinations, although highly synergistic, will require parallel companion diagnostic development to be effectively advanced in patients.

Microbe-Mediated Activation of Toll-like Receptor 2 Drives PDL1 Expression in HNSCC.

As immunotherapies targeting the PDL1 checkpoint have become a mainstay of treatment for a subset of head and neck squamous cell carcinoma (HNSCC) patients, a detailed understanding of the mechanisms underlying PDL1-mediated immune evasion is needed. To elucidate factors regulating expression of PDL1 in HNSCC cells, a genome-wide CRISPR profiling approach was implemented to identify genes and pathways conferring altered PDL1 expression in an HNSCC cell line model. Our screen nominated several candidate PDL1 drivers, including Toll-like Receptor 2 (TLR2). Depletion of TLR2 blocks interferon-γ-induced PDL1 expression, and stimulation of TLR2 with either Staphylococcus aureus or a bacterial lipopeptide mimetic, Pam3CSK4, enhanced PDL1 expression in multiple models. The data herein demonstrate a role for TLR2 in modulating the expression of PDL1 in HNSCC models and suggest that microbiota may directly modulate immunosuppression in cancer cells. Our study represents a step toward disentangling the diverse pathways and stimuli regulating PDL1 expression in HNSCC and underscores a need for future work to characterize the complex microbiome in HNSCC patients treated with immunotherapy.

Genetic analysis of sinonasal undifferentiated carcinoma discovers recurrent SWI/SNF alterations and a novel PGAP3-SRPK1 fusion gene.

BACKGROUND: Sinonasal Undifferentiated Carcinoma (SNUC) is a rare and aggressive skull base tumor with poor survival and limited treatment options. To date, targeted sequencing studies have identified IDH2 and SMARCB1 as potential driver alterations, but the molecular alterations found in SMARCB1 wild type tumors are unknown. METHODS: We evaluated survival outcomes in a cohort of 46 SNUC patients treated at an NCI designated cancer center and identify clinical and disease variables associated with survival on Kaplan-Meier and Cox multivariate survival analysis. We performed exome sequencing to characterize a series of SNUC tumors (n = 5) and cell line (MDA8788-6) to identify high confidence mutations, copy number alterations, microsatellite instability, and fusions. Knockdown studies using siRNA were utilized for validation of a novel PGAP3-SRPK1 gene fusion. RESULTS: Overall survival analysis revealed no significant difference in outcomes between patients treated with surgery +/- CRT and CRT alone. Tobacco use was the only significant predictor of survival. We also confirmed previously published findings on IDH and SMARC family mutations and identified novel recurrent aberrations in the JAK/STAT and PI3K pathways. We also validated a novel PGAP3-SRPK1 gene fusion in the SNUC cell line, and show that knockdown of the fusion is negatively associated with EGFR, E2F and MYC signaling. CONCLUSION: Collectively, these data demonstrate recurrent alterations in the SWI/SNF family as well as IDH, JAK/STAT, and PI3K pathways and discover a novel fusion gene (PGAP3-SRPK1). These data aim to improve understanding of possible driver mutations and guide future therapeutic strategies for this disease.

The molecular landscape of the University of Michigan laryngeal squamous cell carcinoma cell line panel.

BACKGROUND: Laryngeal squamous cell carcinomas (LSCCs) have a high risk of recurrence and poor prognosis. Patient-derived cancer cell lines remain important preclinical models for advancement of new therapeutic strategies, and comprehensive characterization of these models is vital in the precision medicine era. METHODS: We performed exome and transcriptome sequencing as well as copy number analysis of a panel of LSCC-derived cell lines that were established at the University of Michigan and are used in laboratories worldwide. RESULTS: We observed a complex array of alterations consistent with those reported in The Cancer Genome Atlas head and neck squamous cell carcinoma project, including aberrations in PIK3CA, EGFR, CDKN2A, TP53, and NOTCH family and FAT1 genes. A detailed analysis of FAT family genes and associated pathways showed disruptions to these genes in most cell lines. CONCLUSIONS: The molecular profiles we have generated indicate that as a whole, this panel recapitulates the molecular diversity observed in patients and will serve as useful guides in selecting cell lines for preclinical modeling.

Clinical characteristics, HIV status, and molecular biomarkers in squamous cell carcinoma of the conjunctiva in Ghana.

BACKGROUND AND AIMS: Conjunctival squamous cell carcinoma (CSCC) varies in incidence geographically from 0 to 1 case per 100 000 per year globally. Additionally, the incidence of CSCC is known to increase 49% for every 10° decrease in latitude. Since the onset of the AIDS epidemic, there has been a trend of increasing incidence of CSCC in Africa, and despite relatively stable levels of ultraviolet (UV) exposure, there is an observed 12 times greater risk of developing CSCC when individuals are infected with HIV. In this study, we aim to analyze the clinical characteristics and biomarkers of CSCC in Ghana. METHODS: In this study, a registry review of patients from January 2011 to May 2016 with CSCC at Komfo-Anokye Teaching Hospital in Kumasi, Ghana, was performed (n = 64). Tumor blocks of the CSCC were analyzed for the expression of various biomarkers. RESULTS: In this study, the median age of onset of CSCC is 46.5 years old (range of 20-90 y old). Fifty one and a half percent (n = 33) of the cohort is female. There is a low rate of smoking and alcohol use in our CSCC cohort. Thirty-nine percent (n = 12) of Ghanaian men with CSCC are HIV-, while only 12% (n = 4) of women are HIV-. Fifteen patients had metastasis to lymph nodes or other tissues, and we observed a statistically significant relationship between HIV infection and metastasis (P = 0.027, chi-squared test). We observed no statistically significant relationship between known prognostic CSCC biomarkers and HIV status, age, or tumor stage. CONCLUSION: Better characterization of CSCC could have a profound impact on the prevention, early identification, and treatment of CSCC in Africa. A retrospective chart analysis and collection of tumor samples can be challenging in this region due to methods of record keeping and stigma attached to clinical data such as HIV testing and smoking and alcohol use. As a result, in this study, data were often incomplete leading to inconclusive results and analysis that should be interpreted with caution. Future studies should consider a prospective study design that gathers clinical data in a standardized format and ensures fresh tissue from CSCC tumors.

The genomic landscape of UM-SCC oral cavity squamous cell carcinoma cell lines.

OBJECTIVES: We sought to describe the genetic complexity of 14 UM-SCC oral cavity cancer cell lines that have remained uncharacterized despite being used as model systems for decades. MATERIALS AND METHODS: We performed exome sequencing on 14 oral cavity UM-SCC cell lines and denote the mutational profile of each line. We used a SNP array to profile the multiple copy number variations of each cell line and use immunoblotting to compare alterations to protein expression of commonly amplified genes (EGFR, PIK3CA, etc.). RNA sequencing was performed to characterize the expression of genes with copy number alterations. RESULTS: The cell lines displayed a highly complex network of genetic aberrations that was consistent with alterations identified in the HNSCC TCGA project including PIK3CA amplification, CDKN2A deletion, as well as TP53 and CASP8 mutations, enabling genetic stratification of each cell line in the panel. Copy number FISH and spectral karyotyping analysis demonstrate that cell lines retain chromosomal heterogeneity. CONCLUSIONS: Collectively, we developed an important resource for future oral cavity HNSCC cell line studies and highlight the complexity of genomic aberrations in cell lines.

Nuclear localization signal sequence is required for VACM-1/CUL5-dependent regulation of cellular growth.

VACM-1/CUL5 is a member of the cullin family of proteins involved in the E3 ligase-dependent degradation of diverse proteins that regulate cellular proliferation. The ability of VACM-1/CUL5 to inhibit cellular growth is affected by its posttranslational modifications and its localization to the nucleus. Since the mechanism of VACM-1/CUL5 translocation to the nucleus is not clear, the goal of this project was to determine the role that the putative nuclear localization signal (NLS) we identified in the VACM-1/CUL5 (640PKLKRQ646) plays in the cellular localization of VACM-1/CUL5 and its effect on cellular growth. We used site-directed mutagenesis to change Lys642 and Lys644 to Gly and the mutated cDNA constructs were transfected into COS-1 cells. Mutation of the NLS in VACM-1/CUL5 significantly reduced its localization to the nucleus and compromised its effect on cellular growth. We have shown previously that the antiproliferative effect of VACM-1/CUL5 could be reversed by mutation of PKA-specific phosphorylation sequence (S730AVACM-1/CUL5), which was associated with its increased nuclear localization and modification by NEDD8. Thus, we examined whether these properties can be controlled by the NLS. The mutation of NLS in S730AVACM-1/CUL5 cDNA compromised its proliferative effect and reduced its localization to the nucleus. The immunocytochemistry results showed that, in cells transfected with the mutant cDNAs, the nuclear NEDD8 signal was decreased. Western blot analysis of total cell lysates, however, showed that VACM-1/CUL5 neddylation was not affected. Together, these results suggest that the presence of the NLS, both in VACM-1/CUL5 and in S730AVACM-1/CUL5 sequences, is critical for their control of cell proliferation.

Changing the paradigm: the potential for targeted therapy in laryngeal squamous cell carcinoma.

Laryngeal squamous cell carcinoma (LSCC) remains a highly morbid and fatal disease. Historically, it has been a model example for organ preservation and treatment stratification paradigms. Unfortunately, survival for LSCC has stagnated over the past few decades. As the era of next-generation sequencing and personalized treatment for cancer approaches, LSCC may be an ideal disease for consideration of further treatment stratification and personalization. Here, we will discuss the important history of LSCC as a model system for organ preservation, unique and potentially targetable genetic signatures of LSCC, and methods for bringing stratified, personalized treatment strategies to the 21(st) century.

Identification of Targetable ERBB2 Aberrations in Head and Neck Squamous Cell Carcinoma.

IMPORTANCE: ERBB2 (formerly HER2) is an important drug target in breast cancer, where anti-ERBB2 therapy has been shown to lead to improvements in disease recurrence and overall survival. ERBB2 status in head and neck squamous cell carcinoma (HNSCC) has not been well studied. Identification of ERBB2-positive tumors and characterization of response to ERBB2 therapy could lead to targeted treatment options in HNSCC. OBJECTIVE: To identify ERBB2 aberrations in HNSCCs and investigate the potential for ERBB2-targeted therapy in HNSCCs. DESIGN, SETTING, AND PARTICIPANTS: A retrospective case series of patients with laryngeal (42 tumor specimens) and oral cavity (94 tumor specimens) SCC enrolled in the University of Michigan Head and Neck Specialized Program of Research Excellence was conducted. Publicly available sequencing data (The Cancer Genome Atlas), as well as data from other studies, were reviewed to identify additional mutations and overexpression in ERBB2 in HNSCC. Established HNSCC cell lines were used for follow-up in vitro analysis. The study was conducted from October 1, 2014, to August 30, 2015. INTERVENTIONS: With the use of targeted, amplicon-based sequencing with the Oncomine Cancer Panel, the copy number and mutation status of commonly altered genes in HNSCCs were assessed. Immunohistochemical staining was performed on tissue microarrays of HNSCCs to assess the expression of ERBB2. Western blotting for HNSCC cell line ERBB2 expression and cell survival assays after treatment with ERBB2 inhibitors were performed. MAIN OUTCOMES AND MEASURES: The prevalence of ERBB2 genetic aberrations and ERBB2 overexpression in laryngeal and oral cavity SCCs, prevalence of ERBB2 aberrations in HNSCC in The Cancer Genome Atlas, ERBB2 protein expression in HNSCC cell lines, and response of HNSCC cell lines to targeted ERBB2 inhibitors. RESULTS: Of the 42 laryngeal SCC samples screened by targeted sequencing, 4 (10%) were positive for ERBB2 amplification. Two of these samples showed ERBB2 overexpression on immunohistochemistry. Two of the 94 oral cavity SCC samples (2%) were positive for ERBB2 on immunohistochemistry. Analysis of 288 patients from publicly available HNSCC sequencing data revealed 9 amplifications (3%) in ERBB2. Protein expression was variable across HNSCC cell lines, and a subset of these cell lines showed responsiveness to anti-ERBB2 therapy. CONCLUSIONS AND RELEVANCE: ERBB2 aberrations were identified in a subset of HNSCCs. These tumors may be responsive to targeted therapy against ERBB2. Screening for ERBB2 aberrations and applying targeted therapy in ERBB2-positive patients may be useful in personalized therapy trials, particularly in patients who are refractory to current treatment paradigms.

The potential for tumor suppressor gene therapy in head and neck cancer.

Head and neck squamous cell carcinoma remains a highly morbid and fatal disease. Importantly, genomic sequencing of head and neck cancers has identified frequent mutations in tumor suppressor genes. While targeted therapeutics increasingly are being investigated in head and neck cancer, the majority of these agents are against overactive/overexpressed oncogenes. Therapy to restore lost tumor suppressor gene function remains a key and under-addressed niche in trials for head and neck cancer. Recent advances in gene editing have captured the interest of both the scientific community and the public. As our technology for gene editing and gene expression modulation improves, addressing lost tumor suppressor gene function in head and neck cancers is becoming a reality. This review will summarize new techniques, challenges to implementation, future directions, and ethical ramifications of gene therapy in head and neck cancer.

The Tip of the Iceberg: Clinical Implications of Genomic Sequencing Projects in Head and Neck Cancer.

Recent genomic sequencing studies have provided valuable insight into genetic aberrations in head and neck squamous cell carcinoma. Despite these great advances, certain hurdles exist in translating genomic findings to clinical care. Further correlation of genetic findings to clinical outcomes, additional analyses of subgroups of head and neck cancers and follow-up investigation into genetic heterogeneity are needed. While the development of targeted therapy trials is of key importance, numerous challenges exist in establishing and optimizing such programs. This review discusses potential upcoming steps for further genetic evaluation of head and neck cancers and implementation of genetic findings into precision medicine trials.