目的：探讨珠子参多糖（panax japlcus var polysaccharide，PJPS）对胃癌MKN45细胞增殖和凋亡的影响及其调控机 制。方法：选用人胃癌细胞系HGC27、MGC803、MKN45和胃黏膜上皮细胞株GES-1，分别将let-7a mimics、let-7a inhibitor转染 进MKN45细胞； 以100 μg/ml PJPS处理胃癌细胞系并挑选后续实验细胞株为MKN45细胞；分别添加0、10、50、100、120 μg/ml PJPS处理转染后各组MKN45细胞， 用CCK-8法、流式细胞术分别检测MKN45细胞增殖活力和细胞凋亡率， 用Western blotting 检测MKN45细胞中细胞周期依赖性激酶6（cycle dependent kinase 6，CDK6）和凋亡相关蛋白的表达， 用qPCR法检测调控胃癌细 胞增殖的miRNAs表达水平。用双荧光素酶报告基因实验验证let-7a和CDK6的靶向关系。结果：与其他胃癌细胞比较，100 μg/ml PJPS可显著抑制 MKN45 细胞的增殖活力（P<0.01）；同时，100 μg/ml PJPS 处理后，可显著上调MKN45细胞中let-7a的表达 （P<0.01）。双荧光素酶报告基因实验证实CDK6是let-7a的靶基因。进一步实验显示，PJPS通过上调let-7a靶向抑制CDK6的表 达，从而抑制MKN45细胞的增殖并诱导其凋亡（均P<0.01）。结论：PJPS通过调控let-7a/CDK6分子轴抑制胃癌MKN45细胞的 增殖并诱导其凋亡。

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.

海南省卫生计生委科研资助项目（No.19A200161)