Effects Of MiR-21 On The Malignant Biological Behavior Of Human Breast Cancer MCF-7 Cell Line And Its Possible Mechanism

Purpose:To explore the effect of miR-21 on the proliferation,migration,invasion and apoptosis of human breast cancer MCF-7 cell line and its preliminary mechanism.Methods:1.Successfully construct an untransfected control group,an empty plasmid-transfected miRNA-NC group,and a miR-21 inhibitor group transfected with miR-21 inhibitor by transfecting the MCF-7 cell line by lipofection,using qRT-PCR detects the transfection effect.2.MTT method,cell scratch test,cell invasion test,flow cytometry to detect the proliferation,migration and invasion ability and apoptosis level of MCF-7 cell line.3.WB method was used to detect the change of PTEN expression in human breast cancer MCF-7 cell line.Results:1.qRT-PCR detects the expression of miR-21 in the control group,miRNA-NC group and miR-21 inhibitor group,and the results suggest that the miR-21 inhibitor group is in a low expression state.The qRT-PCR test results showed that the expression of miR-21 in the miR-21 inhibotor group was significantly lower than that of the negative control group and the blank group,and the difference between the three was statistically significant using one-way analysis of variance(P<0.001).2.MTT test results showed that at 0h among the three groups,they’re cell proliferation rate was no statistically significant difference.but at 24 h,48h and 72 h miR-21 inhibitor group’s cell proliferation rate was the slowest(P<0.001).3.In the invitro cell scratching experiment 24 hours later measure the three group’s migration width,the control group’s 0.59±0.33 mm,the miRNA-NC group’s0.57±0.38 mm and the miR-21 inhibitor group’s 0.34±0.20 mm.Transwell assay indicated that the number of cells passing through micropores in miR-21 Inhibitor group(66.33±8.62)was significantly lower than that in control group(114.67±9.02)and miRNA-NC group(113.67±11.02)(P<0.001).4.Flow cytometry detected MCF-7’s apoptosis rate.the control group,miRNA-NC group and miR-21 Inhibitor group was6.05±0.25%,6.00±0.19% and 15.47±0.60%,respectively,MiR-21 inhibitor group’s apoptosis rate was significantly higher than other two groups(P<0.001).5.Western blot was used to detect the expression of PTEN protein in three groups of cells and the expression intensity was taken as the PTEN/GAPDH gray scale ratio.The results indicated that the expression of PTEN protein was increased in the miR-21 Inhibitor group with low expression of miR-21(P<0.001).Conclusion: 1.After inhibiting the expression of miR-21,it promotes the apoptosis of human breast cancer MCF-7 cell line and inhibits its proliferation,migration and invasion ability.2.Inhibition of miR-21 expression may affect the malignant biological behavior of human breast cancer MCF-7 cell line by regulating PTEN protein.