Aim To explore the effect of connexin 43 ( Cx 4 3 ) on acquired gefitinib-resistance in human non small cell lung cancer ( NSCLC ) . Methods HCC827 GR, a gefitinib-resistant ( GR) NSCLC cell lines from their parental cells was established by gradually in-creasing the concentration of gefitinib. Gefitinib effica-cy in HCC827 and HCC827 GR cells was detected by MTT assay. Expression of Cx43 mRNA in HCC827 and HCC827 GR cells was determined by RT-PCR. The protein expressions of Cx43 and phospho-Akt ( p-Akt) in these cells were detected by Western blot. The func-tional gap junction intercellular communication ( GJIC ) was measured by parachute assay. The cellular locali-zation of Cx43 protein was evaluated by immunofluores-cence staining. Results MTT assay showed less ge-fitinib cytotoxicity in HCC827 GR cells than that in their parental cells with IC50 of (10. 84 ± 0. 021) μmol ·L-1 versus (0. 07 ± 0. 019) μmol·L-1 , respective-ly. Moreover, both mRNA and protein expressions of Cx43 in HCC827 GR cells were significantly lower than those in HCC827 cells ( P<0. 05 ) . However, the p-Akt protein in HCC827 GR cells was obviously higher than that in HCC827 cells ( P<0. 05 ) . Furthermore, treatment with LY294002 caused a significant reduced p-Akt expression, but a significant increased Cx43 ex-pression in HCC827 GR cells. Moreover, no detecta-ble GJIC was found in HCC827 and their GR cells with or without RA ( a well-defined GJIC enhancer ) treat-ment. Immunofluorescence staining clearly showed that Cx43 protein accumulated in the cytoplasm of HCC827 and their GR cells. Conclusion The down-regulation of Cx43 expression in cytoplasm of HCC827 GR cells may contribute to the acquired gefitinib resistance in NSCLC cells by GJIC-independent activation of PI3 K/Akt signaling pathway.

Objective To investigate the effect of miR-218-1-3p on the proliferation,cycle,and apoptosis of A549 cells in non-small-cell lung cancer.Methods miR-218-1-3p was transfected into non-small cell lung cancer A549 cells by LipofectamineTM 2000 Reagent,and the expression of miR-218-3p was detected by real-time PC R.Invasion and migration were assayed using the Transwell method.The effect of miR-218-1-3p on the proliferation of A549 cells was assayed by the MTS method.Changes in the cell cycle and apoptosis of A549 cells transfected with miR-218-1-3p was detected by flow cytometry.Changes in indicators related to cell proliferation,cycle,and apoptosis were detected by fluorescence quantitative PCR.Results Compared to the control group,the cell proliferation of A549 cells was significantly inhibited (P ＜ 0.05) and the proportion of cells in the S and G2-M phases was significantly decreased when miR-218-1-3p was up-regulated.In addition,compared with the control group,the early apoptotic rate was significantly increased by up-regulating miR-218-1-3p.We further detected indicators related to cell proliferation,cycle,and apoptosis and found that CYCLIN-D1 and BCL-2 were significantly downregulated.Conclusion miR-218-1-3p may inhibit proliferation,induce cell cycle arrest,and promote cell apoptosis of non-small cell lung cancer A549 cells by regulating CYCLIN-D 1 and BCL-2.