Circ-DDX5 inhibits the proliferation and invasion of human breast cancer cell lines by targeting miR-3940 / 基础医学与临床

ABSTRACT

Objective To investigate the expression of circular-RNA DDX5(circ-DDX5)in breast cancer tissues and its relationship with the clinical stage of breast cancer patients,and to analyze the regulatory mechanism of circ-DDX5 on the proliferation and invasion of human breast cancer cell line.Methods The expression level of circ-DDX5 in breast cancer tissues and its correlation with the clinical stage of breast cancer patients were analyzed by TCGA database.Bioinformatics analysis and dual-luciferase reporter gene experiments verified the targeting rela-tionship between circ-DDX5 and miR-3940.The correlation between circ-DDX5 and miR-3940 expression in breast cancer tissues was analyzed by TCGA database.The expression level of circ-DDX5 in breast cancer SK-BR-3,MDA-MB-231,BT-549,MCF-7,and HCC-1937 cells was detected by RT-qPCR.The circ-DDX5 over-expression plasmid and negative control plasmid were transfected into MDA-MB-231 cells,which were named circ-DDX5 group and NC group,respectively.The proliferation and invasion of MDA-MB-231 cells in the circ-DDX5 group and the NC group were detected by colony formation assay and Transwell assay.The expressions of proliferation pheno-type protein and invasion phenotype protein of MDA-MB-231 cells were detected by Western blot.The expression level of miR-3940 in MDA-MB-231 cells of circ-DDX5 group and NC group was detected by RT-qPCR.Results The expression of circ-DDX5 in breast cancer tissues was lower than that in adjacent tissues(P＜0.01)and the ex-pression level of circ-DDX5 was negatively correlated with the clinical stage of breast cancer patients(P＜0.01).There was a targeting relationship between circ-DDX5 and miR-3940(P＜0.01).The expression of circ-DDX5 and miR-3940 in breast cancer tissue was negatively correlated(P＜0.01).The expression of circ-DDX5 in human breast cancer cell lines was lower than that in immortalized breast epithelial cells MCF-10A(P＜0.05 or P＜0.01).Compared with the NC group,the over-expression of circ-DDX5 could significantly inhibit the proliferation and in-vasion of MDA-MB-231 cells(P＜0.01),as well as the proliferation phenotype proteins(cyclin C,CDK3)and in-vasion phenotype proteins(Snail,vimentin)expression(P＜0.01)and miR-3940 expression(P＜0.01).Conclu-sions The expression of circ-DDX5 in breast cancer tissues and cells is low.circ-DDX5 inhibits the proliferation and invasion of breast cancer MDA-MB-231 cells by targeting the expression of miR-3940.