BIM (BCL2L11) is a BH3-only pro-apoptotic member of the Bcl-2 protein family. BIM upregulation is required for apoptosis induction by EGFR tyrosine kinase inhibitors (EGFR-TKIs) in EGFR-mutant forms of non-small cell lung cancer (NSCLC). Notably, a BIM deletion polymorphism occurs naturally in 12.9% of East Asian individuals, impairing the generation of the pro-apoptotic isoform required for the EGFR-TKIs gefitinib and erlotinib and therefore conferring an inherent drug resistant phenotype. We investigated whether the histone deacetylase (HDAC) inhibitor vorinostat could circumvent EGFR-TKI resistance in EGFR mutant NSCLC cell lines that also harbored the BIM polymorphism.
Our results show how HDAC inhibition can epigenetically restore BIM function and death sensitivity of EGFR-TKI, in cases of EGFR mutant NSCLC where resistance to EGFR-TKI is associated with a common BIM polymorphism.