Effects of miR-126 on the STAT3 signaling pathway and the regulation of malignant behavior in lung cancer cells.

The functions of miR-126-mediated signal transducers and activators of the transcription 3 (STAT3) signal pathway were investigated in regulating the behavior of cells in non-small cell lung cancer (NSCLC). Cultured NSCLC A549 cells were transfected with empty, miR-126 overexpression or miR-126 knocked-down expression plasmids. After transfection efficiency verification by reverse transcription polymerase chain reaction (RT-PCR) and culture for 24 h, methyl thiazolyl tetrazolium (MTT) was applied to detect cell proliferation rate, migration distance was measured in scratch assays, cell cycle was determined through flow cytometry, the mRNA expression level of caspase-3 in cells was detected using RT-PCR and protein expression levels of STAT3 were detected using western blotting. Our results showed the cell proliferation rate was significantly higher in cells of the overexpression group than that in those of the control group (p<0.05) and the rate in the cells of the low-expression group was the lowest among the three groups (p<0.05). The migration distance of the overexpression group cells was significantly longer than that in the control group cells and the shortest migration distance was found in the low-expression group cells (p<0.05). The amount of cells in mitotic phase in the overexpression group was significantly higher than that in the control group and the same amount in the low-expression group was the lowest (p<0.05). The mRNA expression level of caspase-3 of cells in the overexpression group was significantly lower than that of cells in the control group and the highest expression level was found in the low-expression group (p<0.05). Finally, the protein expression levels of STAT3 in cells in the overexpression group were significantly lower than those in the control group and the highest expression levels were identified in the low-expression group (p<0.05). Based on our findings, the cancer-promoting miR-126 can mediate the activation of the STAT3 signal pathway to regulate the malignant biological behavior of NSCLC cells affecting their proliferation, migration, cycle and apoptosis susceptibility.