MicroRNA‑326 inhibits endometrial fibrosis by regulating TGF‑β1/Smad3 pathway in intrauterine adhesions

Abstract

Intrauterine adhesion (IUA), characterized by endometrial fibrosis, may lead to infertility and recurrent pregnancy loss. At present, there is no ideal therapy for IUA. Recent findings have revealed that microRNAs (miRNAs) have a decisive role in the regulation of fibrosis. The aim of the present study was to investigate the molecular mechanism of miRNAs in endometrial fibrosis. The present study compared the expression profiles of miRNAs between endometrial tissues from patients with IUA and normal endometrial tissues using microarray analysis. Validation of miR‑326 level in endometrial tissues was performed using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). Subsequently, the effects of miR‑326 on fibrotic markers including α‑smooth muscle actin (α‑SMA), collagen type I α 1 chain (COL1A1), transforming growth factor‑β1 (TGF‑β1) and fibronectin (FN), were evaluated in endometrial tissues and endometrial stromal cells (ESCs) from patients with IUA. Additional bioinformatics analysis, luciferase reporter assays, RT‑qPCR and western blotting were performed to identify target genes. Additionally, the expression levels of TGF‑β1, p‑Smad3 and Smad3 were quantified to determine whether the anti‑fibrotic role of miR‑326 was associated with the activity of the TGF‑β1/Smad3 signaling pathway. The present study determined that miR‑326 was downregulated in endometrial tissues from patients with IUA and miR‑326 levels were inversely correlated with the expression of TGF‑β1, α‑SMA, COL1A1 and FN. Additional findings revealed that overexpression of miR‑326 inhibited endometrial fibrosis by downregulating these pro‑fibrotic genes. TGF‑β1, an important pro‑fibrogenic mediator, was identified as a direct target of miR‑326. Additionally, overexpression of miR‑326 blocked the activation of the TGF‑β1/SMAD family member 3 (Smad3) signaling pathway by suppressing the expression of TGF‑β1 in ESCs from patients with IUA. The findings of the present study indicated that miR‑326 inhibited endometrial fibrosis by suppressing the TGF‑β1/Smad3 signaling pathway, suggesting that miR‑326 may be a prognostic biomarker and therapeutic target for IUA.

Quantification of the CM-Dil-labeled human umbilical cord mesenchymal stem cells migrated to the dual injured uterus in SD rat

“…Under normal physiological conditions, TGF-β1 can promote the repair and healing of the injured site, making the extracellular matrix in a state of balance, while under pathological conditions, TGF-β1 can stimulate the expression of fibronectin and collagen, inhibit the degradation of the extracellular matrix, and lead to fibrosis and scar tissue formation [33]. Plenty of studies have confirmed that TGF-β1/Smad pathway dysregulation was an important mechanism in tissue fibrosis [34][35][36]. Smad2 and Smad3 are the major downstream regulators and promote TGF-β1 mediate the expression of key tissue fibrosis genes, while Smad7 serves as a negative feedback regulator of the pathway, thereby preventing TGF-β1-mediated fibrosis [37,38].…”

Aspirin inhibits endometrial fibrosis by suppressing the�TGF‑β1‑Smad2/Smad3 pathway in intrauterine adhesions

“…TGF-β1 has a specific role in the occurrence and progression of IUAs, and the expression levels of TGF-β1 and Smad3 are positively correlated with the severity of IUAs (15,45). Studies have revealed that miRNA-29b and miRNA-326 may improve endometrial fibrosis in primary human endometrial stromal cells, and can significantly decrease COL1A1, α-SMA and FN expression by inhibiting the TGF-β1/Smad signalling pathway (14,46). In order to investigate the potential mechanism underlying the anti-fibrosis effect of aspirin, the present study examined the expression levels of TGF-β1, Smad2 and Smad3 in the endometrial tissues of two groups.…”

“…Following activation of TGF-β1, activated TGF-β1 binds to its receptor and activates downstream Smad signalling, including Smad2 and Smad3, which serves a crucial role in tissue fibrosis (6,7), including cardiac (8), liver (9), pulmonary (10), pancreatic (11) and renal fibrosis (12), and chronic autoimmune disease Sjögren's syndrome (SS) (13). The mechanism of the TGF-β1/Smad signalling pathway involved in the occurrence of intrauterine adhesions has been described previously (14,15).…”

The Effect of Mitomycin C on Reducing Endometrial Fibrosis for Intrauterine Adhesion

“…In our study, we found that IUA rat fibroblasts were arrested at G1 after treatment with mitomycin C. Moreover, mitomycin C promoted IUA rat fibroblast apoptosis. Mitomycin C inhibited IUA rat uterine fibroblasts to secrete collagen type I, a fibrotic marker that provides mechanical stability for tissues and serves as a functional environment for cells [29,30]. Endometrial fibrosis is associated with the development of IUA.…”