[EGFR-ERK signaling pathway down-regulates miRNA-145 in lung cancer cells]

To investigate the relationship between EGFR activation and down-regulation of miRNA-145 in lung cancer.

Normal human lung epithelia cell line (BEAS-2B), human lung adenocarcinoma cell lines with wild-type EGFR (A549 and H292) and human lung adenocarcinoma cell lines with EGFR mutation (H1975 and H1650) were chosen in this study. The levels of miRNA-145 and p-EGFR were determined by quantitative real-time PCR (qRT-PCR) and Western blotting, respectively, and the relationship between p-EGFR and miRNA-145 levels was analyzed. The miRNA-145 levels were determined by qRT-PCR after activating EGFR with EGF or blocking EGFR signal pathway with AG1478. In addition, ERK1/2 inhibitor U0126 was used to inhibit ERK1/2 activation and then the expression of miRNA-145 was detected.

The miRNA-145 levels were closely negatively related with p-EGFR in lung cancer cells (r = -0.926, P = 0.024). EGF down-regulated miRNA-145 expression, particularly in BEAS-2B cells (53.0%; t = 30.993, P = 0.001) and A549 cells (42.6%; t = 14.326, P = 0.005).The miRNA-145 was up-regulated after inhibiting p-EGFR with AG1478, and significantly enhanced by 67.5% in H1975 cells when treated with AG1478 (t = 8.269, P = 0.014). The ERK1/2 signal pathway was activated by p-EGFR. U0126 restored the miRNA-145 down-regulation induced by EGFR-activation in lung cancer cells.

The activation of EGFR down-regulates miRNA-145 expression through ERK1/2 in lung cancer cells.