Effects of new 17alpha-hydroxylase/C(17,20)-lyase inhibitors on LNCaP prostate cancer cell growth in vitro and in vivo.
Our laboratory has been developing new inhibitors of a key regulatory enzyme of testicular and adrenal androgen synthesis 17alpha-hydroxylase/C(17,20)-lyase (P450c17), with the aim of improving prostate cancer treatment. We designed and evaluated two groups of azolyl steroids: delta5-non-competitive inhibitors (delta5NCIs), VN/63-1, VN/85-1, VN/87-1 and their corresponding delta4 derivatives (delta4NCIs), VN/107-1, VN/108-1 and VN/109-1. The human P450c17 gene was transfected into LNCaP human prostate cancer cells, and the resultant LNCaP-CYP17 cells were utilized to evaluate the inhibitory potency of the new azolyl steroids. VN/85-1 and VN/108-1 had the lowest IC50 values of 1.25 +/- 0.44 nM and 2.96 +/- 0.78 nM respectively, which are much lower than that of the known P450 inhibitor ketoconazole (80.7 +/- 1.8 nM). To determine whether the compounds had direct actions on proliferation of wild-type LNCaP cells, cell growth studies were performed. All of the delta5NCIs and VN/108-1 blocked the growth-stimulating effects of androgens. In steroid-free media, the delta5NCIs decreased the proliferation of LNCaP cells by 35-40%, while all of the delta4NCIs stimulated LNCaP cells growth 1.5- to 2-fold. In androgen receptor (AR) binding studies, carried out to determine the mechanism of this effect, all of the delta4NCIs (5 microM) displaced 77-82% of synthetic androgen R1881 (5 nM) from the LNCaP AR. The anti-androgen flutamide and the delta5NCIs displaced 53% and 32-51% of R1881 bound to AR respectively. These results suggested that the delta5NCIs may also be acting as anti-androgens. We further evaluated our inhibitors in male severe combined immunodeficient mice bearing LNCaP tumour xenografts. In this model VN/85-1 was as effective as finasteride at inhibiting tumor growth (26% and 28% inhibition, respectively) and the inhibitory effect of VN/87-1 was similar to that of castration (33% and 36% inhibition respectively). These results suggest that VN/85-1 and VN/87-1 may be potential candidates for treatment of prostate cancer.
Grigoryev
D N
DN
Department of Pharmacology and Experimental Therapeutics, University of Maryland, School of Medicine, Baltimore 21201, USA.
Long
B J
BJ
Nnane
I P
IP
Njar
V C
VC
Liu
Y
Y
Brodie
A M
AM
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D015741:Metribolone / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology; D013254:Steroid 17-alpha-Hydroxylase / Q000037:antagonists & inhibitors*; D013256:Steroids / Q000627:therapeutic use*; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D013256:Steroids; D015741:Metribolone; D013254:Steroid 17-alpha-Hydroxylase; D017430:Prostate-Specific Antigen