MOLECULAR STUDY OF SEX STEROID-RECEPTOR GENE-EXPRESSION IN HUMAN COLON AND IN COLORECTAL CARCINOMAS

Background: Sex steroid hormones influence function of the human gastr ointestinal tract. Although the specific receptor proteins have been i dentified in surgical specimens of both intestinal mucosa and colorect al carcinomas, it is still unknown whether they are expressed in intes tinal epithelial cells. Methods: Expression of androgen receptor (AR) protein and estrogen receptor (ER) protein was studied by Scatchard an alysis and ELISA (for ER only) in surgical specimens of normal-appeari ng mucosa, colorectal carcinomas, isolated colonocytes, and human colo rectal carcinoma cell lines. Northern analysis was applied to identify the appropriate mRNAs, followed by the sensitive technique of reverse transcription-polymerase-chain-reaction (RT-PCR). Results: AR protein was identified in all surgical specimens analyzed and ER protein in 1 0 out of 13 normal-appearing mucosa specimens and 4 out of 7 colorecta l carcinomas. The receptor proteins were not found in isolated colonoc ytes or in the transformed cell lines. RT-PCR confirmed that none of t he isolated normal colonocytes or transformed colorectal carcinoma-der ived cells expressed these mRNAs. Intestinal smooth muscle cells and f ibroblasts were found to express sex steroid receptor mRNAs. Conclusio ns: Both receptors are present in human large intestine but are expres sed in stromal cells and not in intestinal epithelial cells. We hypoth esize that sex steroids may influence the function of colonocytes indi rectly through stromal-epithelial interactions. (C) 1997 Wiley-Liss, I nc.