MiR-21 In Pancreatic Cancer Cell Proliferation, Apoptosis And Chemosensitivity Of Its Mechanism

Objective:To investigate the impact of miR-21on the biological functions of pancreatic cancer cells as well as the mechanisms of action.Methods:We first transfected MIA PaCa-2pancreatic cancer cells with miR-21mimics and inhibitor (antisense oligonucleotide), then we utilized the cells exposed to irrelevant oligonucleotide as control and investigated the biological functions and mechanisms. Cell proliferation was detected with CCK-8; cell apoptosis was analyzed with flow cytometry and caspase-3activity detection; protein expression was revealed by Western blot; potentially target genes for miR-21were explored with dual luciferase reporter gene assay.Results:The transfection rate was around70%in pancreatic cancer cell line MIA PaCa-2. Compared with the control group, miR-21expression was significantly elevated in cells transfected with miR-21mimics, accompanied by increased tumor cell proliferation, decreased apoptotic activity and impaired chemo-sensitivity to gemcitabine. At the molecular level, the cells exposed to miR-21mimics revealed decreased caspase-3activity, increased bcl-2expression and decreased bax expression. Moreover, for the cells transfected with pRL-TK plasmid containing wildtype3’UTR region of bcl-2, there was an increase in the fluorescence intensity of Renilla reniformis while there showed no such alteration for cells with the plasmid containing mutant3’UTR region of bcl-2. On the other hand, in cells transfected with miR-21inhibitor, reverse results were obtained with decreased proliferation, increased apoptotic activity, increased sensitivity to gemcitabine. At the molecular level, the cells transfected with miR-21inhibitor exhibited increased caspase-3activity and bax expression as well as decreased bcl-2expression. For the cells with pRL-TK plasmid containing wildtype3’UTR region of bcl-2, decreased fluorescence intensity of Renilla reniformis was observed while no changes occurred for cells with the plasmid containing mutant3’UTR region of bcl-2. Conclusions:We demonstrated that miR-21facilitated pancreatic cancer cell proliferation, inhibited apoptosis and increased chemoresi stance, through its regulation on bcl-2protein family. The mechanism might be due to a direct action of miR-21on the3’UTR region of bcl-2protein.