Increased MIR31HG lncRNA expression increases gefitinib resistance in non-small cell lung cancer cell lines through the EGFR/PI3K/AKT signaling pathway.

The aim of the present study was to gain insight into the molecular mechanism of gelitinib resistance in non-snildi cell lung cancer (NSCLC), and demonstrate whether long noncoding RNA (lncRNA) expression signatures differ between gelitinib-sensitive PC9 and gefitinib-resistant PC9 (PC9-R) cell lines. PC9 and PC9-R cells were treated with gefitinib and, after 48 h, proliferation and apoptosis were analyzed using a Cell Counting Kit-8 (CCK-8) assay and flow cytometry. Microarray expression profiling of.IncRNAs was undertaken in both PC9 and PC9-R cells, and the expression profiles were verified by reverse transcription quantitative-polymerase chain reaction. The EGFR/PI3K/AKT signaling pathway and mitochondrial apoptosis protein expression levels were assessed by western blot analysis. The PC9 cell line treated with gefitinib had a more significant effect on cell viability and apoptosis than the PC9-R cell line (P<0.05). Expression of various lncRNAs differed significantly between the two cell lines, and MIR31HG- expression in particular was significantly higher in PC9-R cells. As expected, MIR31HG Inc:RNA knockdown sensitized PC9-R cells to gelitinib, and further experiments revealed that turning off the EGFR/P1.3K/AKT signaling pathway activated expression of p53 in PC9-R cells transfected with si-MIR31HG. Furthermore, PC9-R cells transfected with si-MIR31HG induced cell apoptosis through the mitochondrial apoptosis pathway, and arrested the cell cycle in the G(0)/G(1) phase. The results of the current study suggest that MIR3IHG IneRNA levels in PC9-R cells are higher than in PC9 cells. Furthermore, overexpression of MIR3IHG IncRN.As may contribute to gefitinib resistance in PC9-R cells through the EGFR/P1.3K/AKT pathway, which impacts on cell proliferation, apoptosis and the cell cycle. MIR31HG.IncRNA may therefore be a novel candidate biomarker for future therapeutic strategies involving EGFR-TKIs.