The Expression of MAS1, an Angiotensin (1–7) Receptor, in the Eutopic Proliferative Endometria of Endometriosis Patients

Background/Aim: We demonstrated that AT1 and AT2 are expressed and both pathways balance the renin-angiotensin system in endometriosis. MAS1, a specific receptor of angiotensin (1–7), opposes AT1 pathway-associated tissue remodelling. It is not known whether MAS1 has an effect on the pathogenesis of endometriosis or not. Materials and Methods: Ovarian endometriotic tissues (endo-Ov) and eutopic endometrial tissues (endo-Em) were obtained from 29 patients with endometrial cysts. Normal endometrial tissues (cont-Em) were obtained from patients without endometriosis. Immunohistochemical staining was performed for MAS1, AT1 and AT2 in the endometriosis-associated tissues. The mRNA levels of these receptors were examined by quantitative reverse transcription PCR. Results: MAS1 was immune-positive at the apical side of the glandular epithelium in the endometriotic lesions. The MAS1 mRNA levels in endo-Ov were increased significantly, irrespective of the menstrual cycle phase. The MAS1 mRNA levels were significantly higher in the proliferative-tissues of the endometriosis patients than in those of the controls. The ratio of the MAS1 to the AT1 mRNA in the proliferative tissues was increased predominantly in the endometriosis patients compared with that in the controls. Conclusion: High MAS1 expression in the endometrium might promote the initiation of endometriosis via migration of proliferative tissue.