Knockdown of lncRNA-XIST enhances the chemosensitivity of NSCLC cells via suppression of autophagy.

Drug resistance is the major factor contributing to the failure of chemotherapy in non-small cell lung cancer (NSCLC) patients. Emerging evidence suggests that autophagy plays a vital role in the chemoresistance of many types of tumors. However, the exact mechanism underlying the chemoresistance of NSCLC is still elusive, and it is unclear whether lncRNA-XIST is involved in autophagy and chemoresistance of NSCLC. In the present study, we demonstrated that lncRNA-XIST was overexpressed in NSCLC tumor samples, and knockdown of lncRNA-XIST significantly decreased autophagy by regulation of ATG7 as determined by qPCR and by western blotting. Furthermore, we found that miR-17 was upregulated following knockdown of lncRNA-XIST, and miR-17 mimics decreased the protein levels of ATG7 by directly targeting the 3'-untranslated region of ATG7 mRNA as determined by RT-qPCR and by western blotting. Furthermore, we found that the expression level of lncRNA-XIST was markedly increased in cisplatin-resistant A549 cells as determined by q-PCR. Knockdown of lncRNA-XIST restored the chemosensitivity of cisplatin-resistant A549 cells to cisplatin, which was reversed by miR-17 inhibitor and overexpression of ATG7 as determined by CCK8 assays. This study provides evidence that lncRNA-XIST may be a potential marker of poor response to cisplatin chemotherapy in NSCLC patients and the pathway 'lncRNA-XIST/miR-17/autophagy' may be a promising target for patients with chemoresistant NSCLC.