Development of hormone-dependent prostate cancer models for the evaluation of inhibitors of 17beta-hydroxysteroid dehydrogenase type 3.
17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) are responsible for the pre-receptor reduction/oxidation of steroids at the 17-position into active/inactive hormones, and the 15 known enzymes vary in their substrate specificity, localisation, and directional activity. 17beta-HSD Type 3 (17beta-HSD3) has been seen to be over-expressed in prostate cancer, and catalyses the reduction of androstenedione (Adione) to testosterone (T), which stimulates prostate tumour growth. Specific inhibitors of 17beta-HSD3 may have a role in the treatment of hormone-dependent prostate cancer and benign prostate hyperplasia, and also have potential as male anti-fertility agents. A 293-EBNA-based cell line with stable expression of transfected human 17beta-HSD3 was created and used to develop a whole cell radiometric TLC-based assay to assess the 17beta-HSD3 inhibitory potency of a series of compounds. STX2171 and STX2624 (IC(50) values in the 200-450nM range) were two of several active inhibitors identified. In similar TLC-based assays these compounds were found to be inactive against 17beta-HSD1 and 17beta-HSD2, indicating selectivity. A novel proof of concept model was developed to study the efficacy of the compounds in vitro using the androgen receptor positive hormone-dependent prostate cancer cell line, LNCaPwt, and its derivative, LNCaP[17beta-HSD3], transfected and selected for stable expression of 17beta-HSD3. The proliferation of the parental cell line was most efficiently stimulated by 5alpha-dihydrotestosterone (DHT), but the LNCaP[17beta-HSD3] cells were equally stimulated by Adione, indicating that 17beta-HSD3 efficiently converts Adione to T in this model. Adione-stimulated proliferation of LNCaP[17beta-HSD3] cells was inhibited in the presence of either STX2171 or STX2624. The compounds alone neither stimulated proliferation of the cells nor caused significant cell death, indicating that they are non-androgenic with low cytotoxicity. STX2171 inhibited Adione-stimulated growth of xenografts established from LNCaPwt cells in castrated mice in vivo. In conclusion, a primary screening assay and proof of concept model have been developed to study the efficacy of 17beta-HSD3 inhibitory compounds, which may have a role in the treatment of hormone-dependent cancer. Active compounds are selective for 17beta-HSD3 over 17beta-HSD1 and 17beta-HSD2, non-androgenic with low toxicity, and efficacious in both an in vitro proof of concept model and in an in vivo tumour model.
Day
Joanna M
JM
Oncology Drug Discovery & Women's Health Group, Department of Endocrinology & Metabolic Medicine, & Sterix Ltd., Imperial College London, London W2 1NY, UK. joanna.day@imperial.ac.uk
Tutill
Helena J
HJ
Foster
Paul A
PA
Bailey
Helen V
HV
Heaton
Wesley B
WB
Sharland
Christopher M
CM
Vicker
Nigel
N
Potter
Barry V L
BV
Purohit
Atul
A
Reed
Michael J
MJ
D015067:17-Hydroxysteroid Dehydrogenases / Q000037:antagonists & inhibitors* / Q000145:classification; D000818:Animals; D000970:Antineoplastic Agents / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology*; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D008297:Male; D051379:Mice; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D006728:Hormones; D015067:17-Hydroxysteroid Dehydrogenases; C476565:17beta-hydroxysteroid dehydrogenase type 3