LncRNA XIST promotes carboplatin resistance of ovarian cancer through activating autophagy via targeting miR-506-3p/FOXP1 axis

OBJECTIVE: Resistance to chemotherapy drugs makes ovarian cancer (OC) difficult to treat and ultimately kills patients. Long non-coding RNAs are closely related to carboplatin resistance in OC. In present study, we explored the role of lncRNA X-inactive specific transcript (XIST) on carboplatin resistance in OC. METHODS: Cell viability, proliferation, and apoptosis were assessed through 2,5-diphenyl-2H-tetrazolium bromide, colony formation, and flow cytometry assays, respectively. Microtubule-associated protein 1A/1B-light chain 3 expression was evaluated by immunofluorescence assay to analyze the cell autophagy. The interaction of XIST/miR-506-3p or miR-506-3p/forkhead box protein P1 (FOXP1) was analyzed using RNA immunoprecipitation (RIP) and dual-luciferases reporter assays. The function of XIST/miR-506-3p/FOXP1 axis in vivo was further confirmed by tumor xenograft study and immunohistochemistry. RESULTS: The expression of XIST and FOXP1 increased while miR-506-3p decreased in OC and carboplatin resistance cells. XIST silencing repressed the proliferative and autophagic capacities of carboplatin resistance cells while promoted the apoptosis. XIST overexpression led to the opposite results. XIST targeted miR-506-3p and downregulated its expression. MiR-506-3p inhibition facilitated the proliferative and autophagic capacities while suppressed the apoptosis of cells, XIST knockdown reversed these effects. MiR-506-3p bound to FOXP1. XIST knockdown or miR-506-3p overexpression reversed the increase of cell proliferative and autophagic abilities and the decrease of apoptosis rate induced by FOXP1 overexpression. XIST affected autophagy and carboplatin resistance in vivo via regulating the miR-506-3p/FOXP1 axis. CONCLUSION: XIST knockdown inhibited autophagy and carboplatin resistance of OC through FOXP1/protein kinase B (AKT)/mammalian target of rapamycin pathway by targeting miR-506-3p.