MUTYH knockdown suppresses the growth of hepatocellular carcinoma cells and modulates their response to chemotherapy

DNA-damaging chemotherapies have limited efficacy in hepatocellular carcinoma (HCC), underscoring the need to identify HCC-specific DNA repair vulnerabilities. Previous research identified MUTYH , a base excision repair glycosylase involved in the repair of oxidative DNA lesions, as a poor-prognosis-associated gene, where elevated expression was correlated with reduced overall survival. We therefore established stable MUTYH knockdown in three HCC cell lines, HepG2, Huh7, and Mahlavu; each representing distinct HCC phenotypes. MUTYH knockdown suppressed cell proliferation and migration, altered cell-cycle distribution by increasing G0/G1 accumulation whilst reducing the G2/M fraction, and was accompanied by increased expression of the hypoxia-response genes HIF1A and SLC2A1/GLUT1 across all tested HCC cells. Interestingly, MUTYH knockdown also impaired spheroid growth and morphology even in the absence of treatment. Of note, treatment with cisplatin (CDDP) or temozolomide (TMZ) revealed increased loss of cell viability in conventional monolayer and spheroid cultures under MUTYH knockdown settings, with a more pronounced effect observed for Huh7 cells. Annexin-V/PI staining and cleaved caspase-3 immunoblots confirmed that relative apoptosis rates under CDDP treatment were significantly higher in Huh7 cells with MUTYH knockdown. Collectively, our findings suggest MUTYH as an important regulator of DNA damage tolerance in HCC and a therapeutic target candidate for modulating / augmenting the response to genotoxic chemotherapy.