DNMT3A loss drives a HIF-1-dependent synthetic lethality to HDAC6 inhibition in non-small cell lung cancer

encodes a DNA methyltransferase involved in development, cell differentiation, and gene transcription, which is mutated and aberrant-expressed in cancers. Here, we revealed that loss of promotes malignant phenotypes in lung cancer. Based on the epigenetic inhibitor library synthetic lethal screening, we found that small-molecule HDAC6 inhibitors selectively killed -defective NSCLC cells. Knockdown of by siRNAs reduced cell growth and induced apoptosis in -defective NSCLC cells. However, sensitive cells became resistant when was rescued. Furthermore, the selectivity to HDAC6 inhibition was recapitulated in mice, where an HDAC6 inhibitor retarded tumor growth established from -defective but not parental NSCLC cells. Mechanistically, loss resulted in the upregulation of through decreasing its promoter CpG methylation and enhancing transcription factor RUNX1 binding. Notably, our results indicated that HIF-1 pathway was activated in -defective cells whereas inactivated by HDAC6 inhibition. Knockout of contributed to the elimination of synthetic lethality between and . Interestingly, HIF-1 pathway inhibitors could mimic the selective efficacy of HDAC6 inhibition in -defective cells. These results demonstrated as an HIF-1-dependent vulnerability of -defective cancers. Together, our findings identify as a potential HIF-1-dependent therapeutic target for the treatment of -defective cancers like NSCLC.