Quantitative proteomics and functional analysis identified novel targets for missed abortion

Missed abortion (MA) is a special form of spontaneous abortion that is increasing in incidence. However, the precise molecular mechanisms underlying MA, especially regarding the decidua, are poorly understood. Herein, we identified molecular signaling pathways related to MA by comparing the decidua of women experiencing normal pregnancy and MA using a quantitative proteomics approach based on HPLC-MS/MS and iTRAQ labeling. Integrated bioinformatics analysis of villi and decidua was performed to reveal potential crosstalk signals in closely related tissues. We identified 2277 proteins with high confidence in decidua, of which 232 were differentially expressed in MA samples. Specifically, we reported that integrated quantitative proteomic and bioinformatic analysis revealed altered proteins in MA and the mechanisms underpinning MA involved numerous pathways, especially ribosome and cellular metabolism signaling. Moreover, Importin 9, Cullin 1 and COX6C are critical for MA, and their altered expression might contribute to the pathophysiology of MA. In particular, COX6C was dramatically down-regulated in both decidua and villi of MA. COX6C was also found to be highly expressed in syncytiotrophoblastic and cytotrophoblastic cells in villi and widely expressed in decidua of the control group, but dramatically decreased in the MA group. Functional analysis showed that knockdown of COX6C inhibited apoptosis process in both HTR-8 and SiHa cells, suggesting that COX6C may play protective effects in MA. Thus, this study could help to map the regulatory protein network related to MA and contribute to the pathophysiological mechanisms of MA.