Recurrent implantation failure versus recurrent implantation success: a preliminary study at proteomic level

<b>Objective:</b> This study aimed to find proteomic differences in endometrial receptivity between recurrent implantation failure (RIF) and recurrent implantation success (RIS). This study was a basic proteomic analysis of endometrial biopsies from RIF and RIS women. Differentially expressed proteins between RIF and RIS were screened via isobaric tags for relative and absolute quantification (iTRAQ) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Furthermore, bioinformatic analysis was launched to analyze the difference in the endometrial receptivity between RIF and RIS women. Quantitative P CR and Western blotting were used to validated the study. This study identified 625 differentially expressed proteins in the RIF women compared with RIS women. Bioinformatics analysis demonstrated that these differentially expressed proteins were enriched in ‘Wnt signaling,’ ‘Vascular smooth muscle contraction,’ ‘Ubiquitin mediated proteolysis,’ ‘Tight junction,’ or ‘TGF-beta signaling’ related processes or pathways. Quantitative PCR and Western blotting validation experiments revealed that Claudin-4, p38, PRKAB, IKB-b were unregulated, myosin-2, PKG2 were downregulated significantly in RIF. This study indicated that the alternations of key signal pathways play important roles in the failure of embryo implantation, further studies are warranted to verify if targeting these molecules might be useful to improve the embryo implantation or not.