EXPRESSION OF TRANSCRIPTS ENCODING STEROID UDP-GLUCURONOSYLTRANSFERASES IN HUMAN PROSTATE HYPERPLASTIC TISSUE AND THE LNCAP CELL-LINE

The UDP-glucuronosyltransferase (EC 2.4.1.17) enzymes transform many l ipophilic compounds to more water-soluble products via conjugation wit h glucuronic acid. This conversion is responsible for enhancing the ex cretion of endogenous aglycones such as steroids. To date, several dis tinct isoforms of steroid UDP-glucuronosyltransferases (UGTs) have bee n isolated in the human liver. Among these UGTs, UGT2B7 is specific fo r estriol and 3,4-catechol estrogens, UGT2B15 glucuronidates 17 beta-h ydroxy-C19 steroids while UGT2B10 has as yet an undescribed activity. To further demonstrate the presence of UGTs in peripheral tissues we s tudied the expression of these enzymes in human prostate hyperplastic tissue and the LNCaP cell line. Metabolism studies using intact LNCaP cells in culture indicate the presence of UGT activities involved in t he glucuronidation of 3 alpha-hydroxysteroids (androsterone) and 17 be ta-hydroxysteroids (testosterone and dihydrotestosterone). Northern bl ot analysis of poly(A(+)) RNA from LNCaP cells and prostate using a UG T2B15 cDNA probe revealed two bands of 2.0 and 2.3 kb. In order to ide ntify more specifically the mRNAs detected in Northern blot analysis w e used RNase protection and RT-PCR assays. The relatively high express ion of UGT2B10 and UGT2B15 in LNCaP cells was confirmed by RNase prote ction and RT-PCR, although, these approaches did not allow detection o f UGT2B7 transcripts. Our studies demonstrate the presence of two UGT activities and at least two types of UGT transcripts in both the human prostate and the LNCaP cells.