Relationship between microRNA-95 and proliferation, apoptosis of gastric cancer cells and underlying mechanism

Abstract

Objective To investigate the role of microRNA (miRNA, miR)-95 in the proliferation and apoptosis of gastric cancer cells and the possible mechanism. Methods Real-time quantitative polymerase chain reaction (Real-time PCR) was used to detect the expression of miR-95 in tumor tissues and gastric mucosal tissues from 70 patients with gastric cancer. The patient’s clinicopathological features were recorded and the relationship between miR-95 and these clinicopathologic features was analyzed. The human gastric cancer cell line BGC823 was transfected with anti-miR-95 and the cell viability, cell cycle and apoptosis rate were examined before and after transfection. Simultaneously, Real-time PCR and Western blotting were used to detect the expression of proliferation- and apoptosis-related genes proliferating cell nuclear antigen (PCNA), Cyclin D1, p21, Survivin, Livin and Bad. Results The miR-95 level in gastric cancer was significantly higher than that in gastric mucosal tissues (t=-3.399, P<0.05). Its expression was related to the degree of tumor differentiation and lymph node metastasis. The level of miR-95 in poorly differentiated tumors and in tumors with lymph node metastasis was significantly higher than that in well-differentiated tumors and without lymph node metastasis (t=-3.021, P<0.05; t=3.348, P<0.05). In gastric cancer cell lines AGS, SGC7901, MKN45 and BGC823, and gastric epithelial cell line GES-1, the miR-95 expression was higher in gastric cancer cell lines than GES-1, and highest in BGC823 cells (F=5.998, P<0.05). After transfection of anti-miR-95, the activity of the cells significantly decreased, and the ratio of G0/G1 phase increased (F=39.758, P<0.01), but the ratio of G2/M (F=10.349, P<0.05) and S phases decreased (F=15.118, P<0.01); apoptosis rate increased significantly after anti-miR-95 transfection (F=25.182, P<0.01). The mRNA and protein expression levels of PCNA, Cyclin D1 and Survivin significantly decreased, and those of p21 and Bad increased (P<0.05). Conclusion The up-regulated expression of miR-95 in gastric cancer is associated with tumor differentiation and lymph node metastasis, which may be involved in the progression of gastric cancer by regulating the expression of some proliferative and apoptotic genes. Key words: Gastric cancer; MicroRNA-95; Proliferation; Apoptosis; Clinicopathological features