RUVBL1 is an amplified epigenetic factor promoting proliferation and inhibiting differentiation program in head and neck squamous cancers

Mutations in histone modifying enzymes and histone variants were identified in multiple cancers in The Cancer Genome Atlas (TCGA) studies. However, very little progress and understanding has been made in identifying the contribution of epigenetic factors in head and neck squamous cell carcinoma (HNSCC). Here, we report the identification of RUVBL1 (TIP49a), a component of the TIP60 histone modifying complex as being amplified and overexpressed in HNSCC. RUVBL1 plays a key role in incorporating histone variant H2AZ in chromatin thereby regulating transcription of key genes involved in differentiation, cancer cell proliferation and invasion. H2AZ is also overexpressed in HNSCC tumors thereby regulating RUVBL1/H2AZ dependent transcriptional programs. Patient data analysis of multiple cohorts including TCGA and single cell HNSCC data indicated RUVBL1 over expression as a poor prognostic marker and predicts poor survival. In vitro experiments indicate a pro-proliferative role for RUVBL1/H2AZ in HNSCC cells. RUVBL1 inversely correlates with differentiation program and positively correlates with oncogenic programs, making it a key contributor to tumorigenesis and a vulnerable therapeutic target in HNSCC patients.