Expression Of MiR-27a And MiR-451 And Relationship With Drug Resistance In Malignant Tumor Cells

Objective To investigate the expression of miR-27a and miR-451 in ovarian cancer and breast cancer cells.Methods A2780/Taxol cells were established using stepwise selection. The expression of P-gp protein levels of ovarian cancer and breast cancer cells were measured by western blot. Stem-loop real-time PCR was used to detect expression of miR-27a and miR-451 in ovarian cancer and in breast cancer cells.Results A2780/Taxol cell line was established successfully. The expression levels of P-gp were high in A2780/Taxol and MCF-7/ADM cells and it did not detected in A2780 and MCF-7 cells. The expression of miR-27a was an average of (2.2±0.30)-fold higher in A2780/Taxol cells than in A2780 cells, with a significant difference between the two groups (P<0.05).The expression of miR-451 was an average of (16±0.21)-fold lesser in MCF-7/ADM cells than in MCF-7 cells, with a significant difference between the two groups (P<0.05).Conclusion The expressions of miR-27a and miR-451 were deregulation in A2780/Taxol and MCF-7/ADM cells respectively. Objective To investigate the relationship between miR-27a and drug resistant in paclitaxel-resistant ovarian cancer cells.Methods The A2780 and A2780/Taxol cells were transfected with the mimics or inhibitors of miR-27a or negative control RNA (NC) by Lipofectamine 2000. The expressions of MDR1 mRNA, P-gp and HIPK2 protein levels were measured by real-time PCR and western blot respectively. MTT was used to analyze drug sensitivity. Apoptosis analysis and the fluorescence of remaining Rh-123 were measured by fluorescence activated cell sorter (FACS).Results (1) A2780/Taxol cells transfection with inhibitors of miR-27a showed that the levels of MDR1 mRNA was decreased by (39±0.14)%, P-gp protein level((26±5.3)%) decreased than the NC group ((43±6.7)%), HIPK2 protein level ((30±5.9)%) increased than the NC group ((19±3.8)%), the IC50 (0.53μM) was less than the NC group (6.8μM), apoptosis rate ((32.5±3.6)%) was higher than the NC group ((5.6±2.1)%), the fluorescence intensity of Rh-123 (5.10±0.35) was increased than the NC group (3.30±0.45), and there was a significant difference between two groups (P<0.05). (2) Transfection of A2780 cells with mimics of miR-27a led to increase MDR1 mRNA expression by (121±0.11)% and decrease the sensitivity to paclitaxel (IC50 0.2μM vs.0.06μM). (3) HIPK2 protein level ((8.1±4.9)%) in A2780/Taxol cells management with mimics of miR-27a was decreased than the NC group ((19±3.8)%). There was a significant difference between two groups (P<0.05).Conclusion The expression of miR-27a is upregulated in A2780/Taxol cells, and miR-27a may regulate MDR1/P-gp expression by targeting HIPK2. Transfection with miR-27a inhibitors can downregulate the P-gp expression and activation, and reverse drug resistance in A2780/Taxol cells.Objective To study the role of miR-451 in the development of adriamycin-resistance in breast cancer cells.Methods The mimics of miR-451 and negative control (NC) were transfected into MCF-7/ADM cells by Lipofectamine 2000. The expression levels of MDR1 mRNA and P-gp protein were examined using real time quantitative PCR and western blot respectively. Half-inhibitory concentration (IC50) of doxorubicin was determined by MTT method and the intracellular accumulation of doxorubicin was measured by FACS.Results Transfection of MCF-7/ADM cells with mimics of miR-451 showed that expression of MDR1 mRNA was decreased by (65±12)%, P-gp protein ((31±19)%) was less than the NC group ((83±12)%), the sensitivity of cells to adriamycin enhanced and the IC50 of adriamycin (4.61μM) was less than the NC group (26μM), and the fluorescence intensity of intracellular doxorubicin (28.98±2.9) was increase than the NC group (11.64±2.6). There was a significant difference between two groups (P<0.05).Conclusion The deregulation of miR-451 may be involved in the development of adriamycin-resistance, at least in part, by negatively regulating expression and activation of MDR1/P-gp in MCF-7/ADM cells.