Chromosome 3q26 Gain Is an Early Event Driving Coordinated Overexpression of the PRKCI, SOX2, and ECT2 Oncogenes in Lung Squamous Cell Carcinoma

Summary: Lung squamous cell carcinoma (LSCC) is a prevalent form of lung cancer exhibiting distinctive histological and genetic characteristics. Chromosome 3q26 copy number gain (CNG) is a genetic hallmark of LSCC present in >90% of tumors. We report that 3q26 CNGs occur early in LSCC tumorigenesis, persist during tumor progression, and drive coordinate overexpression of PRKCI, SOX2, and ECT2. Overexpression of PRKCI, SOX2, and ECT2 in the context of Trp53 loss is sufficient to transform mouse lung basal stem cells into tumors with histological and genomic features of LSCC. Functionally, PRKCI and SOX2 collaborate to activate an extensive transcriptional program that enforces a lineage-restricted LSCC phenotype, whereas PRKCI and ECT2 collaborate to promote oncogenic growth. Gene signatures indicative of PKCι-SOX2 and PKCι-ECT2 signaling activity are enriched in the classical subtype of human LSCC and predict distinct therapeutic vulnerabilities. Thus, the PRKCI, SOX2, and ECT2 oncogenes represent a multigenic driver of LSCC. : Liu et al. report that three oncogenes, PRKCI, SOX2, and ECT2, which are coordinately amplified and overexpressed in lung squamous cell carcinoma (LSCC), can transform Trp53−/− mouse lung basal stem cells into tumors with histological and genomic features of LSCC and drive oncogenic signaling necessary to maintain a LSCC phenotype. Keywords: lung squamous cell carcinoma, LSCC, 3q26 copy number gain, CNG, PRKCI, SOX2, ECT2, lung basal stem cells, oncogenic transformation