Transforming Growth Factor-Beta/Mir-143-3p/Cystatin B Axis Is A Therapeutic Target In Human Ovarian Cancer

We previously reported that cystatin B (CSTB) is a progression marker of human ovarian cancer (OC); however, the regulatory mechanism of CSTB and its function in OC remain unclear. The present study aimed to explore the mechanism underlying transforming growth factor-beta (TGF-beta) 1-mediated CSTB regulation, and to examine the function of CSTB on OC cell proliferation and apoptosis. Using the online program, miRWalk, a microRNA (miR)-143-3p was detected, which contains a homologous sequence of the potential binding site to the 3'-untranslated region (3'-UTR) of CSTB. A dual-luciferase reporter assay confirmed the interaction between miR-143-3p and CSTB 3'-UTR. Treating OC cells with miR-143-3p mimics or inhibitors resulted in a decrease or an increase of CSTB expression at mRNA and protein levels, respectively. Additionally, CSTB was significantly overexpressed, whereas miR-143-3p was downregulated in human OC tissues compared with normal ovarian tissues. A negative correlation between miR-143-3p and CSTB mRNA expression was observed in ovarian malignant tumors. The levels of primary and mature miR-143-3p expression were upregulated in OC cells after TGF-beta 1 treatment; the action of TGF-beta 1 was abolished in the presence of an inhibitor of TGF-beta type I receptor. These results indicated an axis between TGF-beta, miR-143-3p and CSTB in OC cells. Furthermore, high levels of CSTB expression were associated with the poor overall survival of patients with OC. Knockdown of CSTB resulted in a decrease in OC cell proliferation and arrested cells in G2/M phase. In addition, suppression of CSTB induced cell apoptosis. In conclusion, CSTB was overexpressed and miR-143-3p was downregulated in ovarian malignant tumors. Mature miR-143-3p directly bound CSTB 3'-UTR, leading to a decrease in CSTB expression in OC cells, which was regulated by TGF-beta 1. Our findings suggest the potential therapeutic application of targeting the TGF-beta/miR-143-3p/CSTB axis for treating patients with OC.