Mechanism research of miR‐34a regulates Axl in non‐small‐cell lung cancer with gefitinib‐acquired resistance

BACKGROUND: To investigate the regulatory mechanism behind miR‐34a‐altered Axl levels in non‐small‐cell lung cancer (NSCLC) with gefitinib‐acquired resistance. METHODS: The expression of miR‐34a, Axl, Gas6 and related downstream signaling proteins in the EGFR mutant NSCLC cell lines were determined by qRT‐PCR and Western blot; PC9‐Gef‐miR‐34a and HCC827‐Gef‐miR‐34a cells were established by transfecting the parent cells with a miR‐34a overexpressing virus, then the expression of Axl, Gas6 and the downstream channel‐related proteins were also compared in PC9‐Gef‐miR‐34a and HCC827‐Gef‐miR‐34a and drug‐resistant strains. The survival rate of the cells were measured by CCK8 assay. A luciferase reporter detected whether Axl was the target of miR‐34a. Finally, a tumor‐bearing nude mouse model was established to verify the relationship between the expression of miR‐34a, Axl and Gas6 mRNA in vivo. RESULTS: The expression levels of Axl mRNA and protein, Gas6 mRNA and protein, and related downstream proteins in PC9‐Gef and HCC827‐Gef cell lines were higher than those in PC9 and HCC827 parental cell lines, while the expression of miR‐34a was lower than it was in the parental cell lines (P < 0.05). The expression of Axl mRNA and protein, Gas6 mRNA and protein, and related downstream signaling proteins in PC9‐Gef and HCC827‐Gef cell lines was higher than the expression in PC9‐Gef‐miR‐34a and HCC827‐Gef‐miR‐34a cells, which overexpressed miR‐34a (P < 0.05). CONCLUSION: The miR‐34a regulation of Axl plays an important role in NSCLC‐acquired gefitinib resistance, and their expression is inversely correlated, which suggests that they can be used as prognostic markers or potential therapeutic targets for NSCLC.