Publications

Abstract

Despite favorable responses to initial therapy, small cell lung cancer (SCLC) relapse occurs within a year and exhibits resistance to multiple drugs. Due to limited accessibility of patient tissues for research purposes, SCLC-patient derived xenografts (PDX) have provided the best opportunity to address this limitation. Here we sought to identify novel mechanisms involved in SCLC chemoresistance. Through in-depth proteomic profiling, we identified MCAM as a markedly upregulated surface receptor in chemoresistant SCLC cell lines and in chemoresistant PDX compared to matched treatment-naive tumors. MCAM depletion in chemoresistant cells reduced cell proliferation and reduced the IC50 inhibitory concentration of chemotherapeutic drugs in vitro. This MCAM-mediated sensitization to chemotherapy occurred via SOX2-dependent upregulation of mitochondrial 37S ribosomal protein 1/ATP binding cassette subfamily C member 1 (MRP1/ABCC1) and the PI3/AKT pathway. Metabolomic profiling revealed that MCAM modulated lactate production in chemoresistant cells that exhibit a distinct metabolic phenotype characterized by low oxidative phosphorylation. Our results suggest that MCAM may serve as a novel therapeutic target to overcome chemoresistance in SCLC.