Adenosine triphosphate-binding cassette transporter G2 expression in endometriosis and in endometrium from patients with and without endometriosis.

To investigate adenosine triphosphate (ATP)-binding cassette transporter G2 (ABCG2) expression in endometriosis and in samples of endometrium from patients with and without endometriosis. Prospective study. University hospital. Patients with and without endometriosis. Endometrial and endometriotic tissues obtained throughout the menstrual cycle. Density of ABCG2(+) microvessels, density of CD31(+) microvessels. No statistically significant differences in the density of ABCG2(+) microvessels were observed between endometrium of patients with and without endometriosis in the proliferative phase and early, middle, and late secretory phases. The density of ABCG2(+) microvessels was statistically significantly higher in the menstrual endometrium of patients with endometriosis compared with patients without endometriosis. The density of ABCG2(+) microvessels was reduced in the ectopic endometrium compared with matched eutopic endometrium except in cases of deep infiltrating endometriosis. The density of ABCG2(+) microvessels was statistically significantly higher in deep infiltrating endometriosis compared with ovarian endometriosis and red and black peritoneal lesions throughout the menstrual cycle. ABCG2 is strongly expressed in the endothelial cells of microvessels of eutopic endometrium, and the density of ABCG2(+) microvessels is reduced in ectopic endometrium except in cases of deep infiltrating endometriosis. ABCG2(+) microvessels may represent an integral part of the pathophysiology of deep infiltrating endometriosis.