Effect of the combination of miR-34a and miR-let7 on the biological properties of pancreatic cancer cells

Abstract

Objective To investigate the influence on biological characteristics in human pancreatic cancer cells after beding transfected by two anti-carcinoma miRNAs at the same time. Methods Pancreatic cancer cells PANC1, SW1990 and normal pancreatic cells AR42J were transfected by miR-34a and(or) miR-let7 by liposome. Cells transfected with negative control miRNA (miR-NC) and untransfected were as controls. The expression of miR-34a and miR-let7 were detected by real-time fluorescent quantitative RT-PCR. The cell proliferation was detected by MTT test and the migration and invasion were evaluated by transwell assay. The apoptosis rate was measured by flow cytometric analysis. Results After being transfected with miRNAs, the expression of miR-34a and miR-let7 in double transfection group (miR-34a and miR-let7 were transfected at the same time). miR-34a transfection group, miR-let7 transfection group was significantly up-regulated than those in miRNA-NC transfection group and untransfected group in PANC1 cells, SW1990 cells and AR42J cells, repectively. The difference which was statistically significant(P<0.05)indicating that cells were successfully transfected. The cell proliferation in double transfection group of PANC1 cells and SW1990 cells were (0.665±0.01, 0.6375±0.03), which were significantly inhibited compared with (0.974±0.03, 0.971±0.05) in miR-NC group and (0.8875±0.05, 0.8625±0.06) in miR-let7 group. The difference was statistically significant(P<0.05). The cell proliferation activity in double transfection group was lower than those in miR-34a group (0.795±0.06, 0.7925±0.06), but did not have statistically significant difference. There was no significant change in AR42J cells. Cell invasion assay showed that the number of PANC1 cells permeating substrate membrane in miR34a group (103.7±3.28) and miR-let7 group (100.7±1.76) were significantly fewer than miR-NC group (231.3±2.6) and untransfected group (153.7±2.6). The number of cells permeating substrate membrane in double transfection group(61.67±3.18)was fewer than miR-34a group and miR-let7 group, respectively. The difference was statistically significant(P<0.01). The migration test had consistent results with invasion test. The changes of invasion and migration in SW1990 cells were similar to those in PANC1 cells. The apoptosis rate of PANC1 cells in miR-34a group, miR-let7 group, double transfection group, miR-NC group and untransfected group was (16.66±1.27)%, (15.46±0.33)%, (23.35±1.80)%, (9.33±0.31)% and (8.83±0.36)% respectively. Single transfection group had higher apoptosis rate than miR-NC group and untransfected group (P<0.05). Double transfection group had a significantly higher apoptosis rate than miR-let7 group (P<0.05), while there was no significant difference between double transfection group and miR-34a group. Conclusions The cell proliferation, invasion and migration in double miRNAs transfected pancreatic cancer cells were significantly down-regulated compared with those in single miRNA transfected cells, while apoptosis rate in double miRNAs transfection group was higher than single miRNA transfection group. Thus, the combination of two anti-cancer miRNAs may exert a more significant synergistic antitumor effect. Key words: Pancreatic neoplasms; Cell line, tumor; miR-34a; miR-let7; Transfection; Molecular biology