Abstract
Gastric cancer has high incidence and mortality, and the mortality ranks second only to lung cancer. Downregulation of miR-133a has been observed in certain types of tumors, and it is involved in gastric cancer. The aim of the present study was to explore the molecular mechanisms of miR-133a and ubiquitin-specific protease 39 (USP39) in gastric cancer. Western blot analysis and RT-PCR were employed to measure miR-133a and USP39 expression. To confirm whether miR-133a targeted USP39, we conducted a luciferase reporter assay. We utilized 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay to detect the effects of miR-133a on gastric cell proliferation. miR-133a was significantly downregulated in cancer tissues and cell lines (HGC-27 and MGC-803), while the expression level of USP39 was higher in tumor tissues than in paracancerous tissues. Upregulated expression of miR-133a and/or USP39 downregulation could inhibit cell proliferation in gastric cancer cells. Furthermore, USP39 was identified as a direct target of miR-133a and the inverse relationship between them was also observed. USP39 was a firsthand target of miR-133a and there was a negative correlation between them. In addition, a low expression of miR-133a or overexpression of USP39 predicted poor prognosis. In conclusion, miR-133a may be a novel therapeutic target of microRNA-mediated suppression of cell proliferation in CC, but the role of the miR-133a/USP39 axis in CC progression needs further study.