The expression and function of microRNA-203 in lung cancer.

We aimed to determine the expression of microRNA-203 (miR-203) in human lung cancer cell lines and to evaluate the effects of miR-203 by targeting survivin, on the lung cancer cell line 95-D to provide potential new strategies for treating lung cancer. The expression of miR-203 was detected using quantitative real-time PCR (qRT-PCR) in the in vitro cultured lung cancer cells A549, HCC827, NCI-H1299, and 95-D as well as in normal human bronchial epithelial cells. Following a 72-h transfection with the miR-203 precursor in 95-D lung cancer cells, the change in miR-203 expression was detected using qRT-PCR and the resulting effect on survivin protein expression was ascertained by Western blot analysis. The influence of miR-203 on the viability of 95-D lung cancer cells was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The effect of miR-203 on 95-D cell proliferation was analyzed using flow cytometry. The consequences of miR-203 expression on 95-D cell apoptosis were analyzed by Annexin V/propidium iodide double staining coupled with flow cytometry. The role of miR-203 in the invasive potential of 95-D cells was studied using a transwell chamber assay. A luciferase reporter gene system was used to verify that survivin is a target gene for miR-203. By qRT-PCR, the expression of miR-203 was lower in lung cancer cells than in normal bronchial epithelial cells (p < 0.01), and the expression of miR-203 in 95-D lung cancer cells was significantly higher after a 72-h transfection with the miR-203 precursor (p < 0.01). After a 72-h transfection with the miR-203 precursor, survivin protein levels in 95-D cells were significantly decreased (p < 0.01). Cell viability, as assessed with an MTT assay, decreased following an increase in miR-203 expression (p < 0.05). The flow cytometry results indicated that after miR-203 expression increased, the cell proliferation index decreased (p < 0.05) and the number of apoptotic cells increased (p < 0.01). Increased miR-203 expression led to a significant decrease in the number of cells that migrated through a transwell chamber membrane (p < 0.01). The luciferase reporter gene system demonstrated that the relative luciferase activity significantly decreased after transfection with the miR-203 precursor (p < 0.05). The expression of miR-203 is downregulated in lung cancer cells. miR-203 negatively regulates survivin protein expression and inhibits the proliferation and invasion of lung cancer cells. Therapeutic strategies that enhance miR-203 expression or silence survivin could potentially benefit lung cancer patients.