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

Objective: To investigate adenosine triphosphate (ATP)-binding cassette transporter G2 (ABCG2) expression in endometriosis and in samples of endometrium from patients with and without endometriosis.

Design: Prospective study.

Setting: University hospital.

Patient(s): Patients with and without endometriosis.

Intervention(s): Endometrial and endometriotic tissues obtained throughout the menstrual cycle.

Main Outcome Measure(s): Density of ABCG2(+) microvessels, density of CD31(+) microvessels.

Result(s): 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.

Conclusion(s): 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.