A Coding Single-Nucleotide Polymorphism in Lysine Demethylase KDM4A Associates with Increased Sensitivity to mTOR Inhibitors

SNPs occur within chromatin-modulating factors; however, little is known about how these variants within the coding sequence affect cancer progression or treatment. Therefore, there is a need to establish their biochemical and/or molecular contribution, their use in subclassifying patients, and their impact on therapeutic response. In this report, we demonstrate that coding SNP-A482 within the lysine tridemethylase gene KDM4A/JMJD2A has different allelic frequencies across ethnic populations, associates with differential outcome in patients with non-small cell lung cancer (NSCLC), and promotes KDM4A protein turnover. Using an unbiased drug screen against 87 preclinical and clinical compounds, we demonstrate that homozygous SNP-A482 cells have increased mTOR inhibitor sensitivity. mTOR inhibitors significantly reduce SNP-A482 protein levels, which parallels the increased drug sensitivity observed with KDM4A depletion. Our data emphasize the importance of using variant status as candidate biomarkers and highlight the importance of studying SNPs in chromatin modifiers to achieve better targeted therapy. SIGNIFICANCE: This report documents the first coding SNP within a lysine demethylase that associates with worse outcome in patients with NSCLC. We demonstrate that this coding SNP alters the protein turnover and associates with increased mTOR inhibitor sensitivity, which identifies a candidate biomarker for mTOR inhibitor therapy and a therapeutic target for combination therapy.