Inactivation of the splicing factor RBM10 limits EGFR targeted therapy response in EGFR mutant lung cancer

Oncogene-driven lung cancers such as those with activating mutations in the epidermal growth factor receptor (EGFR) often harbor additional co-occurring genetic alterations. The significance of most alterations co-occurring with mutant EGFR remains unclear. We report the impact of loss of the mRNA splicing factor RBM10 in human EGFR mutant lung cancer. RBM10 loss decreased EGFR inhibitor efficacy in patient-derived EGFR mutant tumor models. RBM10 regulated mRNA splicing of the mitochondrial apoptotic regulator Bcl-x. Genetic inactivation of RBM10 diminished EGFR inhibitor-mediated apoptosis by altering Bcl-x splicing, decreasing Bcl-xS (pro-apoptotic) and increasing Bcl-xL (anti-apoptotic) levels. Co-inhibition of Bcl-xL and mutant EGFR overcomes resistance induced by RBM10 loss. RBM10 loss was a biomarker of poor response to EGFR inhibitor treatment in clinical samples. Inactivation of the splicing factor RBM10 is a key co-occurring genetic alteration in EGFR mutant tumors that limits EGFR inhibitor efficacy and a potential biomarker of Bcl-xL inhibitor response. Overall design: Examination of 2 different shRBM10 KD in lung cancer PC9 cells.