A Receptor Tyrosine Kinase Network Composed of Fibroblast Growth Factor Receptors, Epidermal Growth Factor Receptor, v-erb-b2 Erythroblastic Leukemia Viral Oncogene Homolog 2, and Hepatocyte Growth Factor Receptor Drives Growth and Survival of Head and Neck Squamous Carcinoma Cell Lines

Abstract

Our laboratory has previously shown that some gefitinib-insensitive head and neck squamous cell carcinoma (HNSCC) cell lines exhibit dominant autocrine fibroblast growth factor receptor (FGFR) signaling. Herein, we deployed a whole-genome loss-of-function screen to identify genes whose knockdown potentiated the inhibitory effect of the FGFR inhibitor, AZ8010, in HNSCC cell lines. Three HNSCC cell lines expressing a genome-wide small hairpin RNA (shRNA) library were treated with AZ8010 and the abundance of shRNA sequences was assessed by deep sequencing. Under-represented shRNAs in treated cells are expected to target genes important for survival with AZ8010 treatment. Synthetic lethal hits were validated with specific inhibitors and independent shRNAs. We found that multiple alternate receptors provided protection from FGFR inhibition, including receptor tyrosine kinases (RTKs), v-erb-b2 erythroblastic leukemia viral oncogene homolog 2 (ERBB2), and hepatocyte growth factor receptor (MET). We showed that specific knockdown of either ERBB2 or MET in combination with FGFR inhibition led to increased inhibition of growth relative to FGFR tyrosine kinase inhibitor (TKI) treatment alone. These results were confirmed using specific small molecule inhibitors of either ERBB family members or MET. Moreover, the triple combination of FGFR, MET, and ERBB family inhibitors showed the largest inhibition of growth and induction of apoptosis compared with the double combinations. These results reveal a role for alternate RTKs in maintaining progrowth and survival signaling in HNSCC cells in the setting of FGFR inhibition. Thus, improved therapies for HNSCC patients could involve rationally designed combinations of TKIs targeting FGFR, ERBB family members, and MET.

FGFR1 Is a Potential Prognostic Biomarker and Therapeutic Target in Head and Neck Squamous Cell Carcinoma

“…Thus, FGFR1 is a potential therapeutic target in HNSCC and AZD4547/gefitinib combination therapy could be adopted to overcome EGFR mediated therapy resistance. The role of EGFR signalling as a resistance mechanism to FGFR inhibitor treatment has previously been reported in several tumor types, including HNSCC (19,36). Furthermore, combining radiotherapy with AZD4547 may be of interest for treating HNSCC, as previous studies report an increased sensitivity of prostate cancer and mesothelioma to radiotherapy when combined with FGFR1 inhibitors (37,38).…”

“…Previous preclinical models demonstrated the efficacy of FGFR inhibitors PD173074, BGJ398, RO4383596 and AZ8010 in HNSCC (16)(17)(18)(19). Here we tested the activity of AZD4547 -a potent and selective pan-FGFR inhibitor currently in phase 2 clinical trial -in HNSCC cell lines.…”

“…Therapies inhibiting FGFR1 have shown to reduce HNSCC development in preclinical models and are currently being tested in clinical trials on solid tumors, including HNSCC (NCT01962532, NCT01004224, and NCT01948297; refs. [16][17][18][19]. Several multikinase inhibitors targeting FGFR and other kinases, for example, dovitinib and lucitanib, have already shown great therapeutic potential in clinical studies on FGFRaberrated breast cancer and various other advanced solid tumors (20,21).…”

Barriers to clinical trial recruitment in head and neck cancer

“…If these elements do not exist, then it can be deemed unfeasible to fund and resource these trials [26]. Researchers have also speculated whether HNSCC may be untreatable using new targeted therapies, given that few targetable oncogenic mutations have been identified in HNSCC, and that clinical progress may only occur through improved prevention and early detection [27,28]. The genomic landscape of HNC has not yielded definitive and obvious targets, as seen in lung, colorectal, and prostate cancers, among others.…”

New Strategies in Human Papillomavirus–Related Oropharynx Cancer: Effecting Advances in Treatment for a Growing Epidemic

“…Preclinical data demonstrate the potential of targeting FGFR signaling in HNSCC, and as is the case with PI3K, evidence exists that EGFR activation may confer resistance (72,73). FGFR inhibitors are currently being studied in broad phase I trials (e.g., NCT01962532), and their evaluation in molecularly defined subsets of HNSCC, including somatic mutations in FGFR2/3 (most relevant for HPV þ OPC), FGFR2/3 fusions, and FGFR amplification, is awaited.…”