Circular RNA circ-SMAD7 promoted ovarian cancer cell proliferation and metastasis by suppressing KLF6.

ABSTRACT

OBJECTIVE: Recently, the roles of circular RNAs (circRNAs) in tumor progression have attracted much attention. Currently, circ-SMAD7 has been identified as an oncogene in cancers. The aim of this study was to investigate the function of circ-SMAD7 in the progression of ovarian cancer. PATIENTS AND METHODS: Circ-SMAD7 expression in both ovarian cancer cells and tissue samples was detected by quantitative Real Time-Polymerase Chain reaction (qRT-PCR). Circ-SMAD7 shRNA was constructed and transfected into the ovarian cancer cells. To identify the function of circ-SMAD7 in ovarian cancer, cell proliferation assay, colony formation assay, transwell assay, and Matrigel assay were conducted, respectively. In addition, qRT-PCR and Western blot assays were performed to elucidate the underlying mechanism and, then, it was analyzed. RESULTS: Circ-SMAD7 expression was remarkably higher in ovarian cancer tissue samples than in corresponding normal tissues. The proliferation of the ovarian cancer cells was significantly inhibited after circ-SMAD7 downregulation. Meanwhile, the migration and invasion of ovarian cancer cells were significantly inhibited after circ-SMAD7 downregulation in vitro. Both the mRNA and the protein expressions of the Krüppel-like factor 6 (KLF6) were remarkably promoted after circ-SMAD7 was knocked down in ovarian cancer cells. Furthermore, the KLF6 expression level was negatively correlated with circ-SMAD7 expression level in ovarian cancer samples. CONCLUSIONS: Our study suggests that circ-SMAD7 promotes the progression of ovarian cancer and enhances cell metastasis and proliferation via suppressing KLF6. In addition, circ-SMAD7 may be a novel therapeutic strategy in ovarian cancer.