Expression of Ah receptor and dioxin-related genes in human uterine endometrium in women with or without endometriosis

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been suggested as a possible etiologic factor for endometriosis, a condition in which endometrium-like tissues are present outside the uterus. The prevailing view pertaining to t he origin of endometriotic cells is that they are from eutopic endometrial cells which regurgitate through fallopian tubes. In order to get insight in to the possible involvement of TCDD in the pathogenesis of endometriosis, w e suspected that TCDD may act differently on the endometrium with or withou t endometriosis. To address this, we examined the presence of messenger RNA s of arylhydrocarbon receptor (AhR), AhR nuclear translocator (Arnt) and tw o dioxin-responsive genes, cytochrome P-450 1B1 (CYP1B1) and downstream of tyrosine kinases (p62(dok)), in the endometrium of women with or without en dometriosis using semi-quantitative reverse transcription-polymerase chain reaction. All the genes were expressed throughout the menstrual cycle. The expression level of p62(dok) was higher in the proliferative phase than in the secretory phase. In contrast, the expression levels of AhR, Arnt and CY P1B1 seemed to be constant during the cycle. In terms of the comparison bet ween non-endometriosis and endometriosis group, the mRNA levels of AhR, Arn t, CYP1B1 and p62(dok) were essentially similar. Interestingly, AhR mRNA le vel was significantly lower in smokers than in non-smokers. Based on the re gression analysis, significant linear and positive correlations were observ ed between AhR and Arnt mRNA levels, and between Arnt and p62(dok) mRNA lev els. In summary, expression of AhR and dioxin-related genes in the endometr ium did not differ in women with or without endometriosis.