MiR-21/PTEN signaling modulates the chemo-sensitivity to 5-fluorouracil in human lung adenocarcinoma A549 cells

An aberrant expression of microRNA-21 (miR-21) has been found in multiple human cancers, including lung carcinoma. Our work aims at investigating the role of miR-21 in human lung adenocarcinoma A549 cells and cells treated with 5-fluorouracil and their potential molecular mechanisms. A549 cells were transfected with an miR-21 mimic, an miR-21 inhibitor, and their respective negative controls using Lipofectamine 2000. Real-time quantitative PCRs (qRT-PCRs) was applied to evaluate the cells' miR-21 expression levels. EdU incorporation and a cell viability assay were used to confirm the cell proliferation. Flow cytometry was performed to analyze the effects of miR-21 on the A549 cell cycle determination. Using flow cytometry and western blot analysis, we measured the A549 cell apoptosis and necrosis and the potential mechanism. Our findings demonstrated that the overexpression of miR-21 decreased 5-fluorouracil-induced apoptosis and necrosis, and the opposite effects were obtained by the suppression of miR-21. Further, we found that the phosphatase and tensin homologue (PTEN) was regulated by the alteration of miR-21 in A549 cells treated with 5-fluorouracil. Finally, we co-transfected an miR-21 mimic or/and PTEN into A549 cells and found that the anti-apoptotic effects of the miR-21 mimic on the A549 cells could be reversed by overexpressing PTEN. Our present work indicated the involvement of the miR-21/PTEN axis in the 5-fluorouracil-induced cell apoptosis of NSCLC. Therefore, the inhibition of the miRNA-21/PTEN pathway may be a novel therapeutic target to block 5-fluorouracil-induced chemotherapy resistance in NSCLC.