Gloria Halverson

Promoter Hypermethylation of Progesterone Receptor Isoform B (PR-B) in Endometriosis

The physiological effects of progesterone (P) is mediated by two isoforms of progesterone receptors (PRs): PR-A and PR-B. Progestins have long been used in the treatment of endometriosis but unfortunately the relief of pain is relatively short-term. In addition, about 9% of women with endometriosis simply do not respond to progestin therapy due to reasons unknown. In fact, a general tendency for relative progesterone resistance within eutopic and ectopic endometrium of women with endometriosis and the downregulation of PR-B, but not PR-A, in endometriosis have been noted. Since promoter hypermethylation is well-documented to be associated with transcriptional silencing, we sought to determine the methylation status of the PR-A and PR-B promoter regions in the epithelial component of endometriotic implants using a combination of laser capture microdissection (LCM), methylation specific PCR, and bisulfite sequencing. We found that the promoter region of PR-B, but not PR-A, is hypermethylated in endometriosis as compared with controls. In addition, the PR-B expression was significantly reduced in the ectopic endometrium. Our finding suggests that progesterone resistance in endometriosis in general and the down-regulation of PR-B, but not PR-A, in particular, are a result of promoter hypermethylation of PR-B, but not PR-A. This, in conjunction with our reported aberrant methylation of HOXA10 in the eutopic endometrium of women with endometriosis, strongly suggests that endometriosis is an epigenetic disease. This perspective should potentially open up new avenues for the delineation of pathogenesis of endometriosis, and might also lead to novel ways to treat the disease through reversing aberrant methylation via pharmacological means.

Genomic alterations in ectopic and eutopic endometria of women with endometriosis.

Background/Aims: Ectopic and eutopic endometria of women with endometriosis have been shown to contain genomic alterations. In this study, we sought to identify genomic alterations in both ectopic and eutopic endometria of 5 women with endometriosis and to examine whether the two tissues share any genomic alterations. We also attempted to classify tissue samples based on the alteration profiles. Methods: Laser capture microdissection was used to harvest epithelial cells. High-resolution comparative genomic hybridization microarrays were used to identify genomic alterations in eutopic and ectopic endometria from 5 women with endometriosis. The results were validated by real-time RT-PCR and loss of heterozygosity analysis. Results: All 5 patients had genomic alterations in their eutopic and ectopic endometria. The ectopic and eutopic endometria shared a sizable portion of genomic alterations. Cluster analysis of the genomic alteration profile correctly and consistently classified tissue samples from the 5 patients into two groups: peritoneal implants and ovarian cysts. Conclusions: The correct classification of tissue samples into two groups suggests that these two subtypes of endometriosis may have distinct genomic alteration profiles and are thus distinct entities, as previously proposed. The shared alterations are likely the ones that harbor genes responsible for an increased propensity of endometrial debris to implant to the ectopic sites and for early events that lead to the establishment of lesions. Alternatively, these shared alterations may harbor genes that are dysregulated in both eutopic and ectopic endometria. The identified genomic alterations should help to zero in genes involved in the pathogenesis of endometriosis in future studies.