Effects of high progesterone in in-vitro fertilization cycle on DNA methylation and gene expression of adhesion molecules on endometrium during implantation window.

Purpose: High progesterone is associated with low implantation rate. Our previous study demonstrated that DNA methylation in endometrium was increased in women with high progesterone in IVF cycles. However, the DNA methylation status is still not yet confirmed, and how it affects endometrial receptivity in high progesterone is still unknown. Current study investigated the effects of high progesterone on DNA methylation and gene expression of adhesion molecules on endometrium during implantation window.
Methods: A cohort study included 20 women with high progesterone (HP) and 20 with normal progesterone (NP) on the day of human chorionic gonadotropin (hCG) administration after controlled ovarian hyperstimulation in IVF cycle. Endometrial tissues were collected on the 7th day after hCG administration. Immunohistochemical staining of DNA methyltransferases (DNMT1 and DNMT3B) and adhesion molecules (MUC1, CDH1 and CTNNB1) were performed. Methylation of MUC1, CDH1, and CTNNB1 promoter regions was detected by Sequenom MassARRAY or bisulfite sequencing PCR. RT-qPCR was used to quantify mRNA expression levels, and correlation of methylation and gene expression level of the adhesion molecules were determined.
Results: DNMT3B, but not DNMT1, in nucleus of luminal and glandular epithelial cells in HP group was significantly higher than that in NP group. Promoter regions of CDH1 and CTNNB1, but not MUC1, in endometrium of HP group were hypermethylated. Protein and mRNA expression of MUC1, CDH1, and CTNNB1 in endometrium of HP group was significantly lower than that in NP group. Level of DNA methylation was negatively correlated with the gene expression of CDH1 and CTNNB1, but not MUC1.
Conclusions: DNA hypermethylation and low expression of adhesion molecules on endometrium were associated with high progesterone during implantation window, which may contribute to the underlying epigenetic mechanism in the failure of IVF treatment.