Abstract:

Methods The gastric cancer tissue and the adjacent tissue of 68 patients with gastric cancer confirmed by pathological diagnosis were collected.The expression levels of miR-431-3p mRNA and carboxy-terminal domain phosphatase 1 （CTDP1） mRNA in gastric cancer tissue， adjacent tissue， human normal gastric mucosal epithelial GES-1 cells and human gastric cancer cells （MKN-28， MGC-803， MKN-45， SGC-7901， HGC-27 cells ）were detected by real-time fluorescence quantitative PCR （RT-qPCR） method；the expression levels of CTDP1 protein in the above cells and the expression levels of cytochrome C（Cyt C），B cell lymphoma-2 （Bcl-2）， and Bcl-2 associated X protein （Bax） in the SGC-7901 cells in various groups were detected by Western blotting method； the correlation between miR-431-3p and CTDP1 mRNA expression level was analyzed by Pearson correlation analysis；the targeting relationship between miR-431-3p and CTDP1 was detected by dual luciferase reporter gene experiment； the miR-431-3p mimic and CTDP1 over-expression lentivirus were transfected into the SGC-7901 cells separately or at the same time.The cells were divided into blank group， vector over-expression（mimic NC） group，miR-431-3p over-expression （miR-431-3p mimic） group，vector lentivirus（vector） group， CTDP1 over-expression lentivirus （CTDP over-expression）group and miR-431-3p mimic+CTDP1 over-expression （co-transfection） group.The proliferation activities of the cells in various groups were detected by MTT assay； the clone formation numbers of the SGC-7901 cells in various groups were detected by clone formation assay；the apoptotic rates of the SGC-7901 cells in various groups were detected by flow cytometry. Results Compared with the adjacent tissue， the expression level of miR-431-3p in the gastric cancer tissue was decreased （P<0.01），and the expression level of CTDP1 mRNA was increased （P<0.01）， and there was a negative correlation between them （r=－0.316， P=0.009）. Compared with the GES-1 cells， the expression levels of miR-431-3p in the other five kinds of gastric cancer cells were decreased （P<0.01）， and the expression levels of CTDP1 mRNA and protein were increased （P<0.05）. The results of dual luciferase reporter system showed that miR-431-3p targetedly regulated the expression of CTDP1. Compared with blank group and mimic NC group， the expression levels of CTDP1 and Bcl-2 proteins， proliferation activity，and number of clone formation of the SGC-7901 cells in miR-431-3p group were decreased （P<0.05）， while the apoptotic rate， expression levels of Cyt C and Bax proteins were increased （P<0.05）. Compared with blank group and vector group， the expression levels of CTDP1 and Bcl-2 proteins， proliferation activity， and number of clone formation of the SGC-7901 cells in CTDP1 over-expression group were increased （P<0.05）， while the apoptotic rate， the expression levels of Cyt C and Bax proteins were decreased （P<0.05）. Compared with blank group and miR-431-3p group， the expression levels of CTDP1 and Bcl-2 proteins， proliferation activity，and number of clone formation of the SGC-7901 cells in co-transfection group were increased （P<0.05）， while the apoptotic rate， expression levels of Cyt C and Bax proteins were decreased （P<0.05）. Conclusion Over-expression of miR-431-3p can inhibit the proliferation and promot the apoptosis of the human gastric cancer cells， and its mechanism may be related to targeted down-regulation of the CTDP1 gene expression. Objective To discuss the effect of miR-431-3p on the proliferation and apoptosis of the gastric cancer cells，and to elucidate its possible molecular mechanism.

Key words: Stomach neoplasm, MiR-431-3p, Carboxyl terminal domain phosphatase 1, Cell proliferation, Apoptosis