Advanced glycation end products (AGEs) downregulate the miR-4429/PTEN axis to promote apoptosis of fibroblasts in pelvic organ prolapse

BACKGROUND: Pelvic organ prolapse (POP) is a common degenerative disease among females. We previously reported that advanced glycation end products (AGEs), compounds derived from nonenzymatic glycoxidation reactions, accumulated in the human vaginal wall and impaired the function of fibroblasts in the pathogenesis of POP. This study investigated the apoptosis induced by AGEs in human uterosacral ligament fibroblasts and the underlying mechanism. METHODS: Human uterosacral ligament fibroblasts were cultured and identified. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was performed to identify the expression of miR-4429, phosphatase and tensin homolog (PTEN), and caspase-3. Flow cytometric analysis was applied to detect the apoptosis rate of fibroblasts. Dual-luciferase reporter assay was performed to verify the relationship between miR-4429 and PTEN. The overexpression of miR-4429 and the inhibition of PTEN were achieved by cell transfections. Western blot analysis was used to detect the protein levels of PTEN, phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt). RESULTS: The AGEs promoted fibroblast apoptosis both in the POP and the non-POP groups. The expression of PTEN increased in fibroblasts from the POP group or fibroblasts treated with AGEs. It was confirmed that miR-4429 interacted with PTEN messenger RNA (mRNA), and the expression level of miR-4429 was reduced in fibroblasts from the POP group or fibroblasts treated with AGEs. Further, overexpression of miR-4429 alleviated increased PTEN expression and fibroblast apoptosis induced by AGEs. Similarly, inhibition of PTEN expression alleviated increased fibroblast apoptosis induced by AGEs. In addition, the protein expressions of PI3K and phosphorylated Akt were reduced in fibroblasts exposed to AGEs. CONCLUSIONS: We proposed that AGEs induced fibroblast apoptosis by regulating the miR-4429/PTEN/PI3K/Akt pathway in POP. Our results revealed a novel mechanism by which AGEs contributed to the molecular pathological alteration in POP.