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DOI: 10.1055/s-0036-1593096
Nuclear expression of Vitamin D receptor (VDR) and aryl hydrocarbon receptor (AHR) is mutually exclusive in endometrial glandular cells of endometriosis lesions
Background: VDR and AHR are nuclear receptors, which exert their function through binding with ligands and formation of a molecular complex. These complexes translocate to the nucleus and activate the expression of a series of genes with a responsive element to VDR or AHR. Both receptors have been identified to play a role in the pathogenesis of endometriosis (EM), a common gynecologic disorder characterized by the formation of endometrial tissues outside the uterine cavity. Despite numerous therapies, there are no resolute cures for endometriosis at the pharmacological level.
Study design: 45 samples of confirmed normal endometrium (NE) of all three phases of the menstrual cycle from premenopausal non-pregnant women and ectopic endometriosis lesions (EC) of 8 patients diagnosed with ovarian endometriosis were analyzed.
Methods: Tissue samples were stained by immunohistochemistry, using anti-VDR and anti-AHR antibodies. Staining intensity was analyzed with a semi-quantitative assay (IRS).
Results: The expression levels of both VDR (p = 0.02) and AHR (p = 0.03) are significantly higher in the nuclei of endometrial glandular cells in EC compared to NE. Additionally, EC displaying a high expression of VDR did not express AHR and vice versa (coefficient of correlation: -0.97, p = 0.007).
Discussion: EC of ovarian origin show an un-physiologically high expression of both VDR and AHR in the nuclei of endometrial glandular cells. However, their expression is also inversely correlated and mutually exclusive: A high expression level of one receptor is accompanied by a low expression level of the other, suggesting a possible target for the treatment of endometriosis.