Cellular Localization of mRNA Expression of Enzymes Involved in the Formation and Inactivation of Hormonal Steroids in the Mouse Prostate

SUMMARY It is well documented that several tissues, including the prostate, are actively involved in the local formation and inactivation of hormonal steroids. To identify the cell types involved in the formation and inactivation of androgens and estrogens in the ventral lobe prostate, we have localized by in situ hybridization (ISH) a large number of steroidogenic as well as steroid-inactivating enzyme mRNAs in the adult mouse prostate. In parallel studies, we also measured enzyme mRNA levels by quantitative real-time PCR (RTPCR) in ventral lobe prostates. From the results obtained with quantitative RT-PCR, it appears that, with a few exceptions, the enzyme with low mRNA expression could not be detected by ISH. The following enzymes have been localized by ISH: 17 � -hydroxysteroid dehydrogenase (17 � -HSD) types 1, 2, 3, 4, 7, 8, 9, 10, and 11; 5 � -reductase type 2; 5 � reductase type 1; P450 7 � hydroxylase; estrogen sulfotransferase type 1; 11 � -HSD types 1 and 2; and UDP-glucuronosyltransferase 1A6. All of these mRNAs are expressed in the epithelial cells of prostatic acini. Several enzyme mRNAs were also localized in stromal cells. Types 1, 7, and 10 17 � -HSD, estrogen sulfotransferase type 1, and 11 � -HSD types 1 and 2 were found only in epithelial cells. The present results indicate that both epithelial and stromal cells in the mouse prostate play a role in local formation and inactivation of hormonal steroids.