Expression of estrogen receptor-B ( ER-B ) in bengin and malignant prostatic epithelial cells and its correlation...

The role of estrogen and its receptors in the etiology and progression of prostate cancer ( PC ) is poorly understood. In normal and malignant human prostate, estrogen receptor-a is expressed only in the stroma, whereas estrogen receptor-Beta ( ER-Beta ) is present in both normal stroma and epithelium. Because loss of ER-Beta expression is associated with prostate hyperplasia in ER-Beta null mice, this study determined patterns of ERBeta expression in hyperplastic, PIN ( prostatic intraepithelial neoplasia ) and malignant human prostate and associations with tumor progression. Formalin-fixed, paraffin-embedded blocks were obtained from thirty-five patients who underwent radical prostatectomy and pelvic lymphadenectomy for prostate cancer, 15 core biopsies diagnosed as PIN and 10 TURP ( transurethral prostatic resection ) diagnosed as BPH ( benign prostatic hyperplasia ) were assessed for ER-Beta expression using immunohistochemistry. ER-Beta positivity was defined as 5% of cells demonstrating nuclear immunoreactivity. Nine ( 90% ) of the studied BPH cases showed ER-Beta positive expression where they showed 5% ER-Beta positive cells, while eight ( 53% ) of the studied 15 PIN cases were negative for ER-Beta expression. Twenty-nine ( 82.8% ) of the studied adenocarcinoma cases were negative for ERBeta expression, p<0 .0001. The loss of ER-Beta expression is associated with progression from hyperplastic prostate epithelium to PC. The ER-Beta expression is inversely proportional to PCs stage and grade. From these data we can conclude that estrogen can affect prostatic cancerogenesis and neoplastic progression through an ER-Beta mediated process in human prostate tissue. Our data also identify the need for additional studies to address the potential role of ERBeta in the regulation of prostate epithelial cell proliferation at different stages in the development of PC. Key Words:ER Beta - Prostatic hyperplasia - PIN - Prostatic carcinoma.