Abstract:

Objective To investigate the influence of long non⁃coding RNA X⁃inactive specific transcript （lncRNA XIST）on epithelial ⁃mesenchymal transition（EMT）of ovarian cancer cells by regulating miR ⁃340⁃5p. Methods Real⁃time quantitative PCR（RT⁃qPCR）was performed to determine expression levels of lncRNA XIST and miR ⁃340⁃5p in ovarian cancer tissues and cell lines. A2780 cells were divided into a control group，si ⁃NC group，si⁃lncRNA XIST group，si⁃lncRNA XIST+NC inhibitor group，and si⁃lncRNA XIST+miR⁃340⁃5p inhibitor group. Dual ⁃luciferase reporter assay was performed to confirm the regulatory relationship between lncRNA XIST and miR ⁃340⁃5p；scratch test and Transwell assay were performed to detect the migration and invasion abilities ofthe cells. The mRNA and protein expressions of EMT marker proteins（E ⁃cadherin，N ⁃cadherinand Vimentin） were analyzed by RT ⁃ qPCR，Western blot andimmunofluorescence staining. Results In ovarian cancer tissues and cell lines，lncRNA XIST was highly expressed，and miR⁃340⁃5p was in low expression（P < 0.05）. The A2780 cells with the highest expression of lncRNA XIST were selected as a transfection target. lncRNA XIST was able to directly down⁃regulate the expression of miR⁃340⁃5p（P < 0.05）. After transfection of si⁃lncRNA XIST，the level of lncRNA XIST，scratch healing rate，number of invasive cells，and expressions of N⁃cadherin and Vimentin were decreased，whereasexpression of E⁃cadherin was increased；after co⁃transfection of si⁃lncRNA XIST with miR⁃340⁃ 5p inhibitor，the above indexes were reversed（P < 0.05）. Conclusions LncRNA XIST accelerates EMT in ovarian cancer cells by down⁃regulating miR⁃340⁃5p.

Key words:

long non?coding RNA X?inactive specific transcript, miR?340?5p, ovarian cancer, epi? thelial?mesenchymal transition