Long noncoding RNA XIST inhibition promotes Leydig cell apoptosis by acting as a competing endogenous RNA for microRNA-145a-5p that targets SIRT1 in late-onset hypogonadism.

Leydig cell (LCs) apoptosis is responsible for decreased serum testosterone levels during late-onset hypogonadism (LOH). Our study was designed to illustrate the regulatory effect of lncRNA XIST on LCs and to clarify its molecular mechanism of action in LOH. The Leydig cells (TM3) was treated by 300 μM H₂O₂ for 8 h to establish Leydig cell oxidative stress model in vitro. The expression levels of lncRNA XIST in the testicular tissues of patients with LOH were measured using fluorescence in situ hybridization (FISH). The interaction between lncRNA XIST/SIRT1 and miR-145a-5p was assessed using starBase and dual-luciferase reporter gene assays. Apoptotic cells and Caspase3 activity were determined by flow cytometry (FCM) assay. Testosterone concentration was determined by ELISA. Moreover, histological assessment of testicles in mice was performed by using HE staining and the TUNEL assay was used to determine apoptosis. We found that the lncRNA XIST was downregulated in the testicular tissues of LOH patients and mice and in H₂O₂-induced TM3 cells. XIST siRNA significantly promoted apoptosis, enhanced Caspase3 activity and reduced testosterone levels in H₂O₂-stimulated TM3 cells. Further studies showed that the miR-145a-5p inhibitor reversed the effect of XIST-siRNA on H₂O₂-induced Leydig cell apoptosis. MiR-145a-5p negatively regulated SIRT1 expression, and SIRT1-siRNA reversed the effects of the miR-145a-5p inhibitor on H₂O₂ stimulated TM3 cells. The in vivo experiments indicated that silencing of the lncRNA XIST aggravated LOH symptoms in mice. Inhibition of lncRNA XIST induces Leydig cell apoptosis through the miR-145a-5p/SIRT1 axis in the progression of LOH.