The Effects Of Diesel Exhaust Particles On MiR-21in Human Bronchial Epithelial Cells And Potential Carcinogenic Mechanisms

OBJECTIVE:Diesel Exhaust Particles (DEP) is a major source of air pollution, which may cause pulmonary diseases. This research aims at studying whether DEP can promote tumor occurrence and its carcinogenic mechanism through analyzing the change of the miR-21expression performed by normal bronchial epithelial cells (16HBE) and lung adenocarcinoma cells (A549) after being treated with DEP.METHODS:Extract the total RNA from untreated16HBE and A549to detect the changes of miR-21by real-time quantitative PCR. Then, dissolve DEP in the1640medium to the concentration of100μg/ml. And then add16HBE to the medium. After48hours, extract the total RNA to detect the changes of miR-21performed by the untreated16HBE and the ones treated with DEP through real-time quantitative PCR. The expression quantity changes of PTEN, PI3K, AKT and p-AKT are detected with Western blot. Test the above indicators again after treating with DEP combined with antisense oligonucleotide(AS-miR-21)of miR-21for48h to analyze the potential role of miR-21in the process of DEP causing cancer. Finally, detect the changes of invasion ability, cell migration, cell cycle and apoptosis of16HBE and A549after treating with DEP for48hours. The three results are tested by Transwell, wound healing assay, flow cytometer respectively.RESULTS:The expression quantity of miR-21in untreated A549cells was obviously higher than that in16HBE cells. The quantity of PTEN in A549was lower than that in16HBE. However, the expression quantity of PI3K, AKT and p-AKT increased when compared with that of16HBE. The differences were statistically significant (p<0.05). When adding DEP in16HBE cells, RT-RCR showed that the expression of miR-21was higher in treated cells than that in untreated cells. Western blot showed that compared with the control group, the expression of PTEN was decreased in treated cells, while the expression of PI3K, AKT and p-AKT increased. However, after being treated with DEP combined with antisense oligonucleotide of miR-21, the expression of miR-21was significantly declined and PTEN expression increased significantly. The decreased PTEN expression caused by DEP was reversed, while the expression of PI3K and AKT also obviously decreased, showing a reverse trend. The results also indicated that after being added DEP, the ability of proliferation and migration of16HBE and lung adenocarcinoma cell A549were both decreased, and the cell cycle was arrested in G0/G1phase. The apoptosis rate of16HBE was increased, while the A549had no significant change. Cell invasion of A549was slightly increased, but16HBE decreased.CONCLUTION:The increased expression of miR-21may play an important role in the process of lung carcinogenesis caused by probable carcinogen Diesel Exhaust Particles. And the mechanism may have some relationship with the activation of PTEN/PI3K/AKT pathway. But short-term expose to a large number of Diesel Exhaust Particles did not cause obvious cell carcinogenesis or worsening of cancer in the process of cell cycle, cell apoptosis, cell proliferation and cell invasion.