USP3 promotes proliferation of non-small cell lung cancer through regulating RBM4.

Abstract

Previous studies have shown that ubiquitin specific protease 3 (USP3) is an oncogene. However, the role of USP3 in non-small cell lung cancer (NSCLC) has not been reported. This study aims to explore the expression characteristics of USP3 in NSCLC, and its regulation on the proliferative capacity of NSCLC cells. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was performed to examine the expression levels of USP3 and RNA Binding Motif 4 (RBM4) in 42 pairs of tumor tissues and adjacent tissue specimens collected from NSCLC patients. Meanwhile, the correlation between the messenger ribonucleic acid (mRNA) expressions of USP3 and RBM4, and the clinical indicators and prognosis of NSCLC patients were analyzed. At the same time, mRNA expression of USP3 in NSCLC cell lines was further verified by the qRT-PCR method. In addition, USP3 knockdown and overexpression models were constructed using lentivirus in NSCLC cell lines H1299 and SPCA1. Cell counting kit-8 (CCK-8), cell colony formation, and 5-Ethynyl-2'-deoxyuridine (EDU) assays were performed to evaluate the influence of USP3 on proliferative capacity in NSCLC cells. Finally, Dual-Luciferase reporter assay and rescue experiments were conducted to further explore its underlying molecular mechanism. In this experiment, qRT-PCR results revealed that the expression level of USP3 in tumor tissues of NSCLC patients was remarkably higher than that in adjacent tissues, and the difference was statistically significant. Compared with NSCLC patients with low expression of USP3, those with high USP3 expression suffered much more advanced pathology stage and lower overall survival rate. Proliferation ability of NSCLC cells overexpressing USP3 was remarkably enhanced, while the opposite result was observed in the USP3 knockdown group. Subsequently, RBM4 expression in NSCLC tissue samples was found to be significantly reduced and negatively correlated with USP3 level. In addition, the result of Dual-Luciferase reporter assay demonstrated that USP3 can be targeted by RBM4. Rescue experiments revealed that RBM4 was responsible for NSCLC progression regulated by USP3. The above studies indicated that USP3 expression was remarkably up-regulated in NSCLC tissues, which was closely related to the pathological staging and poor prognosis of NSCLC patients. Therefore, USP3 might accelerate the proliferation of NSCLC cells via regulating RBM4.