Effect of microRNA-762 on the drug resistance to gemcitabine of pancreatic cancer PANC-1 cell line

Objective To explore the effect of microRNA (miRNA, miR)-762 on the drug resistance to gemcitabine (GEM) of pancreatic cancer PANC-1 cells. Methods Real-time quantitative polymerase chain reaction (Real-time PCR) was used to detect the expression of miR-762 mRNA in gemcitabine-resistant pancreatic cancer cell line PANC-1/GEM and the non-drug-resistant cell line PANC-1 of pancreatic cancer. The miR-762 mimics, miR-762 inhibitors and scramble sequences were transfected into PANC-1/GEM cells respectively with Lipofectamine™ 2000. The proliferation and the drug sensitivity of PANC-1/GEM cells to GEM were measured by cell counting kit-8 (CCK-8) assay. The apoptosis of PANC-1/GEM cells was examined by flow cytometry. The expression of apoptosis related proteins was detected by Western blotting. Results The miR-762 expression was significantly up-regulated in PANC-1/GEM cells (2.88±0.37) compared to that in PANC-1 cells (1.22±0.32) (t=7.340, P<0.01), and the difference is statistically significant. The miR-762 mRNA expression in PANC-1/GEM cells were obviously increased after transfection with miR-762 mimics in mimics group (4.96±0.67) as compared with negative control group (2.87±0.45) (t=-4.920, P<0.01), but markedly decreased after transfection with miR-762 inhibitors in mimics group (0.72±0.18) as compared with negative control group (2.87±0.45) (t=8.430, P<0.01). Meanwhile, A450, half maximal inhibitory concentration (IC50) and B cell lymphoma/leukemia-2 (bcl-2), phosphorylated protein kinase B (p-Akt) and phosphorylated glycogen synthase kinase 3β (p-GSK-3β) protein expression in miR-762 mimics group were significantly higher than those in negative control group after transfection, and apoptosis rate and bcl-2 associated X protein (bax) protein expression were significantly lower than those in negative control group after transfection. While A450, IC50 and bcl-2, p-Akt and p-GSK-3β protein expression in miR-762 inhibitors group were significantly lower than those in negative control group after transfection, and apoptosis rate and bax protein expression were significantly higher than those in negative control group after transfection (P<0.01). Conclusion The expression of miR-762 is up-regulated in pancreatic cancer drug resistant cells and can induce the cell proliferation and inhibit cell apoptosis in PANC-1/GEM cells, thus reducing the sensitivity of PANC-1/GEM cells to GEM, which may be associated with the inhibition of pro-apoptotic factor bax expression and the promotion of bcl-2, p-Akt and p-GSK-3β expression. Key words: Pancreatic cancer; MicroRNA-762; Gemcitabine; Chemoresistance