Up-regulation of miR-145 may contribute to repeated implantation failure after IVF-embryo transfer by targeting PAI-1.

Research Question: Repeated implantation failure (RIF) is a major limiting factor in assisted reproductive technology. As miR-145 (also known as MIR145) is up-regulated in patients with RIF, this study asked, what is the molecular mechanism underlying the affect of miR-145 on embryo implantation in RIF?

Design: Ishikawa cells were infected with lentivirus containing miR-145 and miR-145 NC. Massive transcriptome data analyses and bioinformatics analysis were used to search for a potential candidate target of miR-145. The expression of the potential candidate target was detected using quantitative reverse transcription PCR (qRT-PCR) and western blotting in the Ishikawa cells infected with lentivirus containing miR-145 or miR-145 NC. Subsequently, a dual luciferase reporter assay was performed to verify whether the potential candidate target was a novel direct target of miR-145. In addition, expression of PAI-1 (plasminogen activator inhibitor 1, also known as SERPINE1) in endometrial tissue from women with RIF and in control endometrial tissue was examined using qRT-PCR and immunohistochemistry.

Results: Based on massive transcriptome data analyses and bioinformatics analysis, PAI-1 was regarded as a potential candidate target of miR-145. miR-145 overexpression was achieved in Ishikawa cells. PAI-1 was confirmed as a direct target of miR-145 by bioinformatic analysis, qRT-PCR, western blotting and dual luciferase reporter assay. Further, results from the clinical sample indicated that at both the mRNA and protein levels, PAI-1 expression was down-regulated in endometrial tissues from women with RIF compared with control group women, and this was negatively related to miR-145 expression.

Conclusions: The study results suggests that miR-145 may target and down-regulate PAI-1 expression and influence embryo implantation in women with RIF who are undergoing IVF.