CEMIP promotes small cell lung cancer proliferation by activation of glutamine metabolism via FBXW7/c-Myc-dependent axis

Small cell lung cancer (SCLC) is the most malignant lung cancer with rapid growth and early metastasis, but still lacks effective targeted therapies to improve the prognosis. Here, we demonstrated that a novel oncogenic protein, cell migration inducing hyaluronic binding protein (CEMIP), was robustly overexpressed in SCLC tissues than that in noncancerous tissues and high expression of CEMIP predicted poor outcomes in clinical specimens and in large sample size cohorts from public databases (GEPIA 2 and CPTAC). Liquid chromatography mass spectrometry (LC-MS) and in vitro/in vivo functional assays indicated that CEMIP contributed to the proliferation by increasing glutamine consumption and their metabolites (glutamate and glutathione) levels in SCLC cells. Moreover, the addition of a GLS1 inhibitor CB-839 dramatically reduced CEMIP-induced SCLC cell proliferation. Mechanistically, beyond as a scaffold protein, CEMIP facilitates glutamine-dependent cell proliferation through inhibiting c-Myc ubiquitination and increasing c-Myc stabilization and nuclear accumulation via hindering the interaction between FBXW7 (a E3 ubiquitin ligase) and its target substrate c-Myc. Taken together, our findings reveal a novel oncogenic role of CEMIP in sustaining SCLC growth via FBXW7/c-Myc-dependent axis, and provide new evidence that inhibition of CEMIP might be a potential therapeutic strategy for the treatment of SCLC.