Down-regulation of microRNA-26b modulates non-small cell lung cancer cells chemoresistance and migration through the association of PTEN.

To explore the effect of microRNA-26b (miR-26b) in non-small cell lung cancer (NSCLC) cells, we investigated the mRNA levels of miR-26b in 4 NSCLC cell lines and 10 clinical samples from human patients with NSCLC by quantitative reverse transcriptase polymerase chain reaction. It was found that miR-26b was significantly down-regulated in both NSCLC cells and human carcinoma tissues. Synthetic oligonucleotides were used to up-regulate or down-regulate miR-26b in NSCLC cell lines H1299 and A549 cells. Results showed that both down-regulating and up-regulating miR-26b had no effect on cancer cell proliferation in H1299 or A549 cells, whereas miR-26b over-expression increased cancer cell migration and reduced cisplatin chemosensitivity. Phosphatase and tensin homolog (PTEN) was confirmed to be directly bound by miR-26b by dual-luciferase reporter assay, and was down-regulated in miR-26b over-expressing NSCLC cells. Finally, when PTEN was up-regulated in NSCLC cells, it reversed the effects of miR-2b over-expression on NSCLC migration and cisplatin chemosensitivity. In conclusion, our data showed a functional mechanism of miR-26b in regulating NSCLC. It indicates that miR-26b may regulate NSCLC migration and chemosensitivity through the regulation of PTEN.