Subsite-specific differences of estrogen receptor beta expression in the normal colonic epithelium: implications for carcinogenesis and colorectal cancer epidemiology

Objective This study aimed at investigating whether a differential estrogen receptor beta (ER-b) expression between the colonic subsites could correspond to a modification in proliferation, apoptosis, and adhesion of the normal colonocytes. Methods ER-b, Ki-67, Bcl-2, and E-cadherin expressions were investigated immunohistochemically, in normal epithelium biopsies from the ascending and the descending colon of 53 individuals, who underwent colonoscopy for the investigation of anemia and in whom no local pathology was identified. Results ER-b immunoreactivity has been shown to be stronger at the superficial epithelium than the crypts' base, the difference being important only for the ascending colon. In addition, ER-b expression was higher in the superficial epithelium of the ascending colon than that of the descending colon. The variations of ER-b expression did not correspond to the alterations in Ki-67, Bcl-2, and E-cadherin expression. Conclusion A subsite-specific variation of ER-b expression has been shown in the normal colonic epithelium. This modulation of ER-beta might account for some well established specificities of colorectal cancer epidemiology like the right-sided predominance of the neoplasm in women and its gradual shift to more proximal sites over time. Eur J Gastroenterol Hepatol 22:614-619 (C) 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.