Prolonged anovulation causes aberrant endometrial gene promoter methylation changes in women with polycystic ovary syndrome

Abstract

OBJECTIVE: Abnormal expression of steroid hormone receptors in the endometrium of women with polycystic ovary syndrome (PCOS) has been suggested to adversely affect endometrial function. Although aberrant epigenetic regulation of endometrial gene expression has been demonstrated in endometriosis and endometrial adenocarcinoma, epigenetic regulation of endometrial gene expression in PCOS has not been evaluated. We hypothesize that abnormal endometrial gene expression in PCOS may be associated with epigenetic modification of gene promoter sites.DESIGN: Laboratory comparison study.MATERIALS AND METHODS: Endometrial specimens were collected in PCOS (n=3) and control (n=3) subjects. The subjects with PCOS had a proliferative phase that ranged from 5-120 days. Endometrial stromal cells were isolated and grown in culture with subsequent isolation of RNA and DNA. Expression levels of AR, ERβ, and HOXA10 were determined by real time RT-PCR. Results for individual PCOS patients were compared to averaged control results. Differences in methylation patterns at CpG island sites of the promoters for AR, ERβ, and HOXA10 were determined by EpiTyper. Unpaired student t test and one way ANOVA were used for statistical analysis.RESULTS: Compared to controls, PCOS was associated with increased expression of AR and ERβ and decreased expression of HOXA10. Longer proliferative phase duration in PCOS patients was positively associated with the observed changes in gene expression. AR and ERβ promoters were found to be demethylated at specific CpG sites in PCOS patients. No difference was noted in HOXA10 promoter methylation between control and PCOS groups.CONCLUSIONS: Aberrant steroid hormone receptor expression in endometrial stromal cells of women with PCOS is associated with changes in gene promoter methylation. This expression appears to be more pronounced in those subjects who have demonstrated proliferative changes over a longer period of time. OBJECTIVE: Abnormal expression of steroid hormone receptors in the endometrium of women with polycystic ovary syndrome (PCOS) has been suggested to adversely affect endometrial function. Although aberrant epigenetic regulation of endometrial gene expression has been demonstrated in endometriosis and endometrial adenocarcinoma, epigenetic regulation of endometrial gene expression in PCOS has not been evaluated. We hypothesize that abnormal endometrial gene expression in PCOS may be associated with epigenetic modification of gene promoter sites. DESIGN: Laboratory comparison study. MATERIALS AND METHODS: Endometrial specimens were collected in PCOS (n=3) and control (n=3) subjects. The subjects with PCOS had a proliferative phase that ranged from 5-120 days. Endometrial stromal cells were isolated and grown in culture with subsequent isolation of RNA and DNA. Expression levels of AR, ERβ, and HOXA10 were determined by real time RT-PCR. Results for individual PCOS patients were compared to averaged control results. Differences in methylation patterns at CpG island sites of the promoters for AR, ERβ, and HOXA10 were determined by EpiTyper. Unpaired student t test and one way ANOVA were used for statistical analysis. RESULTS: Compared to controls, PCOS was associated with increased expression of AR and ERβ and decreased expression of HOXA10. Longer proliferative phase duration in PCOS patients was positively associated with the observed changes in gene expression. AR and ERβ promoters were found to be demethylated at specific CpG sites in PCOS patients. No difference was noted in HOXA10 promoter methylation between control and PCOS groups. CONCLUSIONS: Aberrant steroid hormone receptor expression in endometrial stromal cells of women with PCOS is associated with changes in gene promoter methylation. This expression appears to be more pronounced in those subjects who have demonstrated proliferative changes over a longer period of time.