Promoter Methylation Regulates Estrogen Receptor 2 in Human Endometrium and Endometriosis1

Abstract

Steroid receptors in the stromal cells of endometrium and its disease counterpart tissue endometriosis play critical physiologic roles. We found that mRNA and protein levels of estrogen receptor 2 (ESR2) were strikingly higher, whereas levels of estrogen receptor 1 (ESR1), total progesterone receptor (PGR), and progesterone receptor B (PGR B) were significantly lower in endometriotic versus endometrial stromal cells. Because ESR2 displayed the most striking levels of differential expression between endometriotic and endometrial cells, and the mechanisms for this difference are unknown, we tested the hypothesis that alteration in DNA methylation is a mechanism responsible for severely increased ESR2 mRNA levels in endometriotic cells. We identified a CpG island occupying the promoter region (À197/þ359) of the ESR2 gene. Bisulfite sequencing of this region showed significantly higher methylation in primary endometrial cells (n ¼ 8 subjects) versus endometriotic cells (n ¼ 8 subjects). The demethylating agent 5-aza-2 0 -deoxycytidine significantly increased ESR2 mRNA levels in endometrial cells. Mechanistically, we employed serial deletion mutants of the ESR2 promoter fused to the luciferase reporter gene and transiently transfected into both endometriotic and endometrial cells. We demonstrated that the critical region (À197/þ372) that confers promoter activity also bears the CpG island, and the activity of the ESR2 promoter was strongly inactivated by in vitro methylation. Taken together, methylation of a CpG island at the ESR2 promoter region is a primary mechanism responsible for differential expression of ESR2 in endometriosis and endometrium. These findings may be applied to a number of areas ranging from diagnosis to the treatment of endometriosis.

Expression of DNA methyltransferases in the mouse uterus during early pregnancy and susceptibility to dietary folate deficiency

“…In addition, both mRNA and protein levels of ESR2 are downregulated in the endometrial stromal cells by DNA methylation of the promoter (Xue et al 2007). Similarly, both prolactin and insulin-like growth factorbinding protein 1, which are vital for decidualization, are upregulated in human endometrial stromal cells that have been treated with a demethylation agent (5 0 -aza-2 0 -deoxycytidine) (Logan et al 2010).…”

“…For example, DNA methylation of the estrogen receptor 2 (ESR2) promoter downregulates ESR2 levels (both mRNA and protein) in endometrial stromal cells (Xue et al 2007). The CpG-rich region within the homeobox A10 promoter is hypermethylated in the endometria of women who have intrauterine devices (Lu et al 2010).…”

Expression Pattern of Stemness-Related Genes in Human Endometrial and Endometriotic Tissues

“…Other studies highlighted a differential expression of the genes SF1 and estrogen receptor beta in endometriotic tissue compared with endometrium. Results indicated that expression was primarily controlled by a methylation-dependent epigenetic mechanism (5,6). In addition, various chromosomal aberrations have been reported in endometriotic samples and in ovarian carcinoma (7).…”

Endometriosis, endometrioma e infertilidad

“…Esto puede deberse a que la secuencia bisulfito de la región CpG (−197/+359) del promotor del gene ESR2 muestra una mayor metilación en células endometriales primarias que en la de células endometriósicas (9).…”