ABSTRACT
@#Objective: To investigate the effect of panax japlcus var polysaccharide (PJPS) on the proliferation and apoptosis of gastric cancer MKN45 cells and its regulatory mechanism. Methods: Human gastric cancer cell lines (HGC27, MGC803, MKN45) and gastric mucosal epithelial cell line GES-1 were selected for this study. Let-7a mimics and let-7a inhibitor were transfected into MKN45 cells; Gastric cancer cell lines were treated with 100 μg/ml PJPS and MKN45 was selected as the subsequent experimental cell line. MKN45 cells were cultured with 0, 10, 50, 100 and 120 μg/ml PJPS, respectively. The proliferation and apoptosis rate of MKN45 cells were detected by CCK-8 and flow cytometry, respectively. Expressions of cell cycle dependent kinase 6 (CDK6) and apoptosis-related proteins in MKN45 cells were detected by Western blotting, and the expression level of miRNAs regulating the proliferation of gastric cancer cells was detectedbyReal-timequantitativePCR(qPCR).TheDualluciferasereportergeneassaywasusedtovalidatethetargeting relationship between let-7a and CDK6. Results: Compared with other gastric cancer cells, 100 μg/ml PJPS significantly inhibited the proliferation of MKN45 cells (P<0.01). At the same time, 100 μg/ml PJPS significantly up-regulated the expression of let-7a in MKN45 cells (P<0.01). The Dual luciferase reporter gene assay confirmed that CDK6 was the target gene of let-7a. Furthermore, PJPS inhibited the expression of CDK6 by up-regulating let-7a, thereby inhibiting the proliferation and inducing apoptosis of MKN45 cells (all P<0.01). Conclusion: PJPS inhibits proliferation and induces apoptosis of gastric cancer MKN45 cells by regulating the let-7a/ CDK6 axis.