Lineage-specific intolerance to oncogenic drivers restricts histological transformation

Abstract Lung adenocarcinoma (LUAD) and small cell lung cancer (SCLC) are thought to originate from different epithelial cell types in the lung. Intriguingly, LUAD can histologically transform into SCLC following treatment with targeted therapies. Here we designed models to follow the conversion of LUAD to SCLC and found the barrier to histological transformation converges on tolerance to Myc, which we implicate as a lineage-specific driver of the pulmonary neuroendocrine cell. Histological transformations are frequently accompanied by activation of the Akt pathway. Manipulating this pathway permitted tolerance to Myc as an oncogenic driver, producing rare, stem-like cells, transcriptionally resembling the pulmonary basal lineage. These findings suggest histological transformation may require the plasticity inherent to the basal stem cell, enabling tolerance to previously incompatible oncogenic driver programs. One-Sentence Summary By modeling histological transformation of lung cancer, we uncover neuroendocrine-specific tolerance to Myc as an oncogenic driver.