Increased expression of miR-641 contributes to erlotinib resistance in non-small-cell lung cancer cells by targeting NF1.

Epidermal growth receptor (EGFR)-targeted tyrosine kinase inhibitors (TKIs) have emerged as first-line drugs for advanced non-small-cell lung cancer (NSCLC) patients with EFGR mutations. However, most patients with NSCLC show acquired resistance to EGFR-TKIs, and low expression of NF1 is a mechanism of EGFR-TKI resistance in lung cancer. However, the mechanism by which NF1 is downregulated in EGFR-TKI-resistant NSCLC is unclear. Here, we found the increased expression of miR-641 in NSCLC cells and human NSCLC samples with resistance to TKI compared to those with sensitive to TKI. In addition, our in vitro experiments show that overexpression of miR-641 induces TKI resistance in NSCLC cells. Furthermore, we identified that miR-641 activates ERK signaling by direct targeting of neurofibromatosis 1 (NF1) in NSCLC cells. Our data show that overexpression of NF1 or silencing of ERK can block miR-641-induced resistance of NSCLC cells to erlotinib treatment. Importantly, our animal experiments show that combination of miR-641 inhibition and erlotinib treatment can significantly inhibit erlotinib-resistant NSCLC growth, inhibit proliferation and induce apoptosis compared to single-drug treatment. Our findings suggest that increased expression of miR-641 significantly contributes to erlotinib resistance development in NSCLC cells through activating ERK signaling by targeting NF1 and that inhibition of miR-641 may reverse acquired resistance of NSCLC cells to erlotinib treatment.

[The effects of NOX4 and TGF-ßinvolved in airway remodeling of Chronic Obstructive Pulmonary Disease].

OBJECTIVE: To investigate the role of nicotinamide adenine dinucleotide phosphate 4 (NADPH4,NOX4) and transforming growth factor-beta (TGF-ß) involve in pathogenesis of airway remodeling in chronic obstructive pulmonary disease (COPD). METHODS: Lung tissues from 36 COPD patients and 19 patients with normal lung function were enrolled in this study. The volume of airway smooth muscle (ASM)mass was evaluated. The expressions of NOX4, collagen Ⅳ (Col Ⅳ) and TGF-ß were tested by a semi-quantitative morphological and/or immunohistochemistry staining method and Western blot, and their correlations with pulmonary functions were analyzed. RESULTS: ①Index of the percentage of the thickness of ASM/external diameter of small airway (WT%) and the percentage of the area of ASM/transverse area of small airway (WA%) were significantly higher in the COPD group than those in controls(P<0.05).②In COPD patients,epithelial cells metaplasia were found and α-SMA and Col Ⅳwere expressed in a part of epithelial cells. The expressions of α-small muscle actin (α-SMA) and Col Ⅰ were increased in COPD patients in comparison with the patients without obstructive airway disorders(P<0.05).③The expression of NOX4 in ASM and epithelial cells of COPD patients was significantly higher in comparison with the patients without COPD. The expression of NOX4 in ASM of small airway were statistically different among different COPD grade (P<0.05). Correlation analysis demonstrated that the level of NOX4 protein in ASM of small airway was inversely associated with pulmonary functions. ④The expression of TGF-ß in COPD was significantly higher than that in patients without COPD. ⑤ Correlation analysis demonstrated that the level of NOX4 protein in ASM of small airway, WT% and WA% were inversely associated with pulmonary functions. CONCLUSIONS: ①The airway remodeling of COPD is characterized by increasing hyperplasia of small airway smooth muscle.②Remodeling of airway smooth muscle associats with severity of airflow limitation in COPD patients. ③The expressions of NOX4, TGF-ß and α-SMA in COPD epithelial cells and small airway smooth muscle cells are significantly enhanced. The expressions of NOX4, α-SMA and TGF-ß are positively correlated with the severity of chronic obstructive pulmonary air flow, suggesting that TGF-ß and NOX4 signaling may be involved in the development of chronic obstructive pulmonary disease airway remodeling.