Concurrent Inhibition of ERK and Farnesyltransferase Suppresses the Growth of HRAS Mutant Head and Neck Squamous Cell Carcinoma

Abstract

Human papilloma virus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) is a common cancer worldwide with an unmet need for more effective, less toxic treatments. Currently, both the disease and the treatment of HNSCC cause significant mortality and morbidity. Targeted therapies hold new promise for patients with HPV-negative status whose tumors harbor oncogenic HRAS mutations. Recent promising clinical results have renewed interest in the development of farnesyltransferase inhibitors (FTIs) as a therapeutic strategy for HRAS-mutant cancers. With the advent of clinical evaluation of the FTI tipifarnib for the treatment of HRAS-mutant HNSCC, we investigated the activity of tipifarnib and inhibitors of HRAS effector signaling in HRAS-mutant HNSCC cell lines. First, we validated that HRAS is a cancer driver in HRAS-mutant HNSCC lines. Second, we showed that treatment with the FTI tipifarnib largely phenocopied HRAS silencing, supporting HRAS as a key target of FTI antitumor activity. Third, we performed reverse-phase protein array analyses to profile FTI treatment-induced changes in global signaling, and conducted CRISPR/Cas9 genetic loss-of-function screens to identify previously unreported genes and pathways that modulate sensitivity to tipifarnib. Fourth, we determined that concurrent inhibition of HRAS effector signaling (ERK, PI3K, mTORC1) increased sensitivity to tipifarnib treatment, in part by overcoming tipifarnib-induced compensatory signaling. We also determined that ERK inhibition could block tipifarnib-induced epithelial-to-mesenchymal transition, providing a potential basis for the effectiveness of this combination. Our results support future investigations of these and other combination treatments for HRAS mutant HNSCC.

Farnesyl-transferase inhibitors show synergistic anticancer effects in combination with novel KRAS-G12C inhibitors

“…In the case of H358, sotorasib and combinational treatment drastically blocked wound closure, likely due to the combined antimigratory and antiproliferative effects. In H358 cells, tipifarnib alone did not reduce wound closure, in line with previous observation that the impact of tipifarnib on cell migration is cell-type dependent [ 42 ].…”

Targeting HRAS in Head and Neck Cancer

“… 43 Rebound induction of ERK and AKT phosphorylation has also been observed in different tumor cell lines treated with tipifarnib, 43,53,54 including HRAS mutant HNSCC cells 53 . Combining tipifarnib with selective ERK1/2 inhibitors (SCH772984 or ulixertinib) also overcame pathway reactivation in HNSCC tumor cell lines in vitro 53 …”

“…Targeted inhibition of the epidermal growth factor receptor or fibroblast growth factor receptor RTKs also potently induced pathway inhibition in vitro , but failed to demonstrate cooperative activity in combination in vivo. 43 Rebound induction of ERK and AKT phosphorylation has also been observed in different tumor cell lines treated with tipifarnib, 43,53,54 including HRAS mutant HNSCC cells 53 . Combining tipifarnib with selective ERK1/2 inhibitors (SCH772984 or ulixertinib) also overcame pathway reactivation in HNSCC tumor cell lines in vitro 53 …”

“…53 Combining tipifarnib with selective ERK1/2 inhibitors (SCH772984 or ulixertinib) also overcame pathway reactivation in HNSCC tumor cell lines in vitro. 53…”

Predicting Deleterious Non-Synonymous Single Nucleotide Polymorphisms (nsSNPs) of HRAS Gene and In Silico Evaluation of Their Structural and Functional Consequences towards Diagnosis and Prognosis of Cancer

“…RAS is considered ‘undruggable’ because the RAS protein lacks a druggable binding pocket [ 3 ]. Mutations in HRAS have been reported in rhabdomyosarcoma, salivary gland carcinoma, thyroid carcinoma, and bladder and mouth carcinoma [ 4 , 5 , 6 , 7 ].…”