The Relationship Among HOXA10, Estrogen Receptor α, Progesterone Receptor, and Progesterone Receptor B Proteins in Rectosigmoid Endometriosis: A Tissue Microarray Study

Background: Very few studies have evaluated the expression of homeobox A10 (HOXA10) and steroid (estrogen and progesterone) receptors exclusively in deep endometriosis. Conclusions drawn from studies evaluating peritoneal and ovarian endometriosis are usually generalized to explain the pathogenesis of the disease as a whole. We aimed to evaluate the expression of HOXA10, estrogen receptor (ER-), progesterone receptor (PR), and PR-B in rectosigmoid endometriosis (RE), a typical model of deep disease. Methods: We used RE samples from 18 consecutive patients to construct tissue microarray blocks. Nine patients each were operated during the proliferative and secretory phases of the menstrual cycle. We quantified the expressions of proteins by immunohistochemistry using the modified Allred score. Result: The HOXA10 was expressed in the stroma of nodules during the secretory phase in 5 of the 18 patients. Expression of ER- (in 16 of 18 patients), PR (in 17 of 18 patients), and PR-B (17 of 18 patients) was moderate to strong in the glands and stroma of nodules during both phases. Expression of both PR (P = .023) and PR-B (P = .024) was significantly greater during the secretory phase. Conclusion: The HOXA10 is expressed in RE, where it likely imparts the de novo identity of endometriotic lesions. The ER-, PR, and PR-B are strongly expressed in RE, which differs from previous studies investigating peritoneal and ovarian lesions. This suggests different routes of pathogenesis for each of the 3 types of endometriosis.