Phenotypic plasticity is a cancer hallmark, and lung adeno-to-squamous transition (AST) triggered by LKB1 inactivation is significantly associated with drug resistance. Clinical data show that squamous transition occurs in certain lung adenocarcinoma patients who relapse from targeted therapy using EGFR tyrosine-kinase inhibitors (TKIs) or KRAS inhibitor. However, the epigenetic regulatory mechanisms involved in AST remain largely unknown.