Development of hormone-dependent prostate cancer models for the evaluation of inhibitors of 17beta-hydroxysteroid dehydrogenase type 3.

Abstract

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.

• Authors: Joanna M Day, Helena J Tutill, Paul A Foster, Helen V Bailey, Wesley B Heaton, Christopher M Sharland, Nigel Vicker, Barry V L Potter, Atul Purohit, Michael J Reed
• Journal: Molecular and cellular endocrinology (Mol Cell Endocrinol) Vol. 301 Issue 1-2 Pg. 251-8 (Mar 25 2009) ISSN: 0303-7207 [Print] Ireland
• PMID: 18786604 (Publication Type: Journal Article)

Chemical References

• Antineoplastic Agents
• Enzyme Inhibitors
• Hormones
• 17-Hydroxysteroid Dehydrogenases
• 17beta-hydroxysteroid dehydrogenase type 3

Topics

• 17-Hydroxysteroid Dehydrogenases (antagonists & inhibitors, classification)
• Animals
• Antineoplastic Agents (analysis, chemistry, pharmacology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Disease Models, Animal
• Drug Evaluation, Preclinical
• Enzyme Inhibitors (analysis, chemistry, pharmacology)
• Hormones (pharmacology)
• Humans
• Male
• Mice
• Prostatic Neoplasms (drug therapy, enzymology, pathology)
• Transfection
• Xenograft Model Antitumor Assays