ARID1A-mutated ovarian cancers depend on HDAC6 activity. Homo sapiens

ARID1A, encoding a subunit of the SWI/SNF chromatin remodeling complex, is the most mutated epigenetic regulator in human cancers. ARID1A and TP53 mutations are typically mutually exclusive. Therapeutic approaches that correlate with ARID1A mutational status remain a challenge. Here, we show that HDAC6 activity is essential in ARID1A-mutated ovarian cancers. Inhibition of HDAC6 activity using a clinically applicable small molecule inhibitor significantly improved the survival of mice bearing ARID1A-mutated ovarian tumors. This correlated with the suppression of growth and dissemination of ARID1A-mutated, but not wild-type, tumors. The dependence on HDAC6 activity in ARID1A-mutated cells correlated with a direct transcriptional repression of HDAC6 by ARID1A. HDAC6 inhibition selectively promoted apoptosis of ARID1A-mutated cells. HDAC6 directly deacetylated the Lysine 120 residue of p53, a pro-apoptotic post-translational modification. Thus, ARID1A mutation inactivates p53’ apoptotic function by upregulating HDAC6. These results indicate that pharmacological inhibition of HDAC6 is a novel therapeutic strategy involving ARID1A-mutation Overall design: RNA-seq transcription profiling of samples with altered HDAC6 activity