MicroRNA-29b Inhibits Endometrial Fibrosis by Regulating the Sp1-TGF-β1/Smad-CTGF Axis in a Rat Model

Abstract

Intrauterine adhesions (IUAs), which are characterized by endometrial fibrosis, increase the risk of secondary infertility and recurrent miscarriage. MicroRNA-29 (miR-29) is a potent inhibitor of TGF-β1/Smad signaling. In this study, we investigated the therapeutic potential of agomir-29b, an miR-29b mimic, in endometrial fibrosis induced by dual injury (uterine curettage and lipopolysaccharide treatment) in a rat model of IUA and explored the underlying mechanism. We found that injured rats developed endometrial fibrosis characterized by increased COL1A1 and α-smooth muscle actin expression and decreased E-cadherin expression, associated with a loss of miR-29b. Overexpression of miR-29b before injury prevented endometrial fibrosis including collagen accumulation and epithelial-mesenchymal transition. Delay of agomir-29b treatment until endometrial fibrosis was established on day 4 also halted the progression of disease. Further experiments indicated that miR-29b inhibited endometrial fibrosis via blockade of the Sp1-TGF-β1/Smad-CTGF pathway. In conclusion, agomir-29b may act as a novel and effective therapeutic agent against IUAs.

Keywords: TGF-β signaling; agomir-29b; endometrial fibrosis; epithelial–mesenchymal transition; intrauterine adhesions.