In androgen target tissues 3a-hydroxysteroid dehydrogenases (3a-HSDs) may regulate the occupancy of androgen receptor (AR) by interconverting 5a-dihydrotestosterone (5a-DHT, a potent androgen) with 5a-androstane-3a,17b-diol (3a-diol, a weak androgen). We have obtained type 2 and type 3 3a-HSD cDNAs expressed in human prostate and overexpressed the enzymes in E. coli. Kinetic studies of these recombinant enzymes show that type 3 3a-HSD functions as both a 3a-and 17b-HSD to inactivate active androgens, whereas, type 3 3a-HSD interconverts 5a-DHT with 3a- diol. Levels of 3a-HSD mRNA were higher in primary cultures of prostatic epithelial cells than stromal cells; and elevated levels of 3a-HSD mRNA were observed in primary cultures of epithelial cells derived from benign prostatic hyperplasia and prostatic carcinoma tissues. Expression of steady state levels of 3a-HSD mRNA is up-regulated by epidermal growth (EGF) in human prostatic cell lines, LNCaP (androgen sensitive) and PC3 (androgen insensitive). The focus of this proposal is to examine the physiological functions of type 2 and type 3 3a-HSD in regulating androgen metabolism and their activities in modulating prostatic cell proliferation will be investigated. This will be accomplished by stably transfecting type 2 and type 3 3a-HSD cDNAs into these cells. Second, levels of endogenous type 2 and type 3 3a-HSD transcripts will be examined in RNA extracted from the cell lines and normal prostate using ribonuclease protection assay (RPA). Third, EGF-regulated type 2 and type 3 3a-HSD mRNA levels will be examined using RPA. Changes in 3a-HSD expression mediated by EGF will be examined in cell lysates by immunotitration of the enzyme activity. Fourth, to understand the constitutive and EGF- regulated type 2 and type 3 3a-HSD expression in prostatic cells, the 5'-flanking regions of the 3a-HSD genes will be sequenced and cis-acting elements responsible for transcription regulation of two isoforms will be identified.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK054925-01
Application #
2614194
Study Section
Special Emphasis Panel (ZRG4-UROL (01))
Project Start
1998-09-28
Project End
1998-11-30
Budget Start
1998-09-28
Budget End
1998-11-30
Support Year
1
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Pharmacology
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
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