Ring Finger Protein 180 Suppresses Cell Proliferation and Energy Metabolism of Non-Small Cell Lung Cancer Through Down-Regulating C-myc

Abstract BackgroundNon-small cell lung cancer (NSCLC) causes a great number of cancer-related mortality worldwide, but the biomarkers for prognosis of NSCLC are scarce because of their inconsistent efficiency. Proteins containing RING finger domain are the key mediator for ubiquitination, which controls cell cycle and regulates tumor progression. Ring Finger Protein 180 (RNF180) has been reported to suppress gastric cancer, whereas its function in NSCLC is still unclear. In this study, the association between RNF180 expression and NSCLC as well as the effect of RNF180 in cellular proliferation and metabolism of NSCLC were investigated. MethodsQuantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical staining were performed to analyse RNF180 levels. Moreover, RNA interference (RNAi) and lentiviral-mediated vector transfections were performed to silence and overexpress RNF180. Further, Cell Counting Kit-8 (CCK-8) was used to assess its biological function in cell proliferation. A xenograft model was used to examine RNF180 function in vivo. ResultsWe found that the expression of RNF180 was decreased in NSCLC tissues, and its expression was positively correlated with the survival rate of NSCLC patients. Furthermore, the overexpression of RNF180 in NSCLC cells suppressed their proliferation, glycolytic activities, and mitochondrial respiration in vitro, and it restricted the tumorigenicity in mice. In addition, RNF180 knockdown promoted NSCLC cell proliferation and energy metabolism, whereas these promotive effects were counteracted by C-myc inhibitor. The underlying anti-NSCLC mechanism of RNF180 involved in the down-regulation of C-myc through ubiquitin-dependent degradation, and subsequently reduced C-myc downstream: lactate dehydrogenase-A (LDHA) and hexokinase-2 (HK2). ConclusionsThese results firstly indicated the anti-tumor properties of RNF180 and its significant correlation with NSCLC, which endorses RNF180 with the potential as efficient prognostic biomarker for tumor recurrence in NSCLC.