Human RECQL5 promotes metastasis and resistance to cisplatin in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) patients have a lower 5-year survival rate, and the distant tumor metastasis and drug resistance are the main reasons for the high mortality. RECQL5, a member of RecQ helicases family, has been linked to tumorigenesis of various cancers expect NSCLC. In the current study, analysis with the Cancer Genome Atlas (TCGA) dataset showed that the level of RECQL5 was elevated in LUAD (Lung Adenocarcinoma) and LUSC (lung squamous carcinomas), two major subtypes of NSCLC, which was confirmed by immunohistochemistry staining on Tissue array slides. The level of RECQL5 was also elevated in NSCLC cell lines. Further, Kaplan-Meier analysis of TCGA dataset suggested that the up-regulated RECQL5 was associated with poor prognosis of LUAD, but not with that of LUSC. Knockdown of RECQL5 significantly inhibited the invasion and migration of NSCLC cells, and suppressed epithelial-mesenchymal transition (EMT) as indicated by the changes of EMT-related proteins, while overexpression of RECQL5 displayed reverse effects. Lung metastasis was also suppressed by RECQL5 knockdown. Additionally, the addition of Akt inhibitor LY294002 reversed the effects of RECQL5 overexpression on cell migration, invasion and EMT. Moreover, knockdown of RECQL5 increased the apoptosis of cisplatin-resistant A549 cell line (A549/DDP) caused by cisplatin treatment. In summary, RECQL5 contributed to the metastasis of NSCLC and assisted NSCLC cells incompletely response to cisplatin therapy, and could be considered as a biomarker or clinical target for NSCLC.