CRISPR Screens Identify PIK3C2A as a Novel Mediator of EGFR Inhibitor Resistance in Head and Neck Squamous Cell Carcinoma

Background: Head and neck squamous cell carcinoma (HNSCC) is a malignancy with poor prognosis and survival. While epidermal growth factor receptor (EGFR) is a known driver of HNSCC, EGFR inhibitors show limited efficacy as monotherapies, suggesting that effective combination therapies are needed. Methods: We performed GeCKO and Kinase CRISPR library screens to identify candidate knockouts that increase EGFR inhibitor sensitivity in resistant HNSCC cells. We validated a candidate using the CellTiter-Glo viability assay following RNA interference and investigated the mechanisms using apoptosis and cell cycle flow cytometry analysis. Results: Kinase CRISPR library screens identified that PIK3C2A gene downregulation enhanced EGFR inhibitor sensitivity in resistant HNSCC cells. Viability assays further validated that PIK3C2A knockdown overcame EGFR inhibitor resistance in HNSCC cells. Conclusions: Our data suggests that PIK3C2A is a novel mediator of EGFR inhibitor resistance in HNSCC. Future studies are required to determine the mechanisms by which PIK3C2A drives EGFR inhibitor resistance.