MUC1-C IS A MASTER REGULATOR OF SMALL CELL LUNG CANCER PROGRESSION

Small cell lung cancer (SCLC) is a recalcitrant malignancy associated with dysregulation of MYC signaling and the CDK-RB-E2F axis. We report that expression of the oncogenic MUC1-C protein in SCLC cells integrates activation of MYC and the E2F pathway. MUC1-C drives MYC and E2F target genes and regulates the G2/M checkpoint, mitotic spindle pathway and replication stress response (RSR). We further show that MUC1-C MYC signaling (i) induces NOTCH2, a marker of pulmonary neuroendocrine (NE) stem cells that are the proposed cell of SCLC origin, (ii) drives NE differentiation, as evidenced by expression of ASCL1 and POU3F2/BRN2, and (iii) promotes self-renewal capacity and tumorigenicity of SCLC cells. Analyses of datasets from SCLC tumors confirmed that MUC1 significantly associates with the MYC pathway. These findings uncover a master role for MUC1-C in promoting progression of the SCLC stem cell state and support MUC1-C as a potential target for SCLC treatment. Overall design: RNA-seq in SCLC cell lines