Inhibition of the activity of ‘basic’ 5 alpha-reductase (type 1) detected in DU 145 cells and expressed in insect cells.
Delos S; Iehle C; Martin PM; Raynaud JP
Laboratoire de Cancerologie Experimentale, Faculte de Medecine, Secteur Nord, Marseille, France.
J Steroid Biochem Mol Biol 1994 Mar; 48 (4): 347-52
LANGUAGE OF PUBLICATION
The purpose of this study was 2-fold: (1) to identify the 5 alpha-reductase (5 alpha-R) isozyme(s) present in DU 145 cells, a human cell-line of low androgen sensitivity derived from a cerebral metastasis of an epithelial prostate cancer; and (2) to compare the inhibitory potencies of three compounds on the ‘basic’ 5 alpha-R isozyme expressed in a baculovirus-directed insect cell system. Conversion of testosterone (T) into 5 alpha-dihydrotestosterone (DHT) in DU 145 cells was measured by HPLC coupled to a Flo-one HP radioactivity detector. DU 145 cells exhibited 5 alpha-R activity (21 pmol DHT/min/mg protein) at pH 7.4 which disappeared at pH 5.5 suggesting that, of the two genomically distinct human isozymes identified so far, type 1 5 alpha-R is expressed in DU 145 cells. This was confirmed by at least two observations: first, 5 alpha-R activity in DU 145 cells was inhibited with much higher potency by 4-MA than by finasteride which is known to be a very poor competitor of the ‘basic’ enzyme (IC50s = 2.8 +/- 0.2 and 264 +/- 55 nM, respectively). Second, only the type 1 5 alpha-R cDNA and not type 2 5 alpha-R cDNA hybridized with DU 145 RNA. A high potency differential was also recorded for the inhibition of ‘basic’ type 1 5 alpha-R expressed in a baculovirus-directed-insect cell system by these two compounds, 4-MA being considerably more active than finasteride (Ki = 8.4 +/- 2.3 and 330 +/- 9 nM, respectively). This inhibition was competitive. On the other hand, inhibition by an n-hexane lipid/sterol extract of Serenoa repens (LSESr) was non-competitive and, when expressed in terms of recommended therapeutic doses, was 3-fold greater for LSESr than for finasteride. These studies suggest that LSESr might exert a regulatory inhibitory activity due to its specific lipid/sterol composition. (AUTHOR)
MJTR: Brain Neoplasms SC. Gene Expression. Isoenzymes AI. Prostatic Neoplasms EN. Testosterone 5-alpha-Reductase AI.
MNTR: Animal. Azasteroids PD. Baculoviridae GE. Brain Neoplasms EN. Chromatography, High Pressure Liquid. Finasteride PD. Human. Hydrogen-Ion Concentration. Isoenzymes AN. Isoenzymes GE. Kinetics. Male. Moths. Recombinant Proteins AI. Stanolone AA. Stanolone ME. Stanolone PD. Support, Non-U.S. Gov’t. Testosterone ME. Testosterone 5-alpha-Reductase AN. Testosterone 5-alpha-Reductase GE. Tumor Cells, Cultured. JOURNAL ARTICLE
RNUM: EC 22.214.171.124 (Testosterone 5-alpha-Reductase); 0 (Azasteroids); 0 (Isoenzymes); 0 (Recombinant Proteins); 521-18-6 (Stanolone); 57-85-2 (Testosterone); 73671-86-0 (17-N,N-diethylcarbamoyl-4-methyl-4-azaandrostane-3-one); 98319-26-7
IDEN: ISSN: 0960-0760. JOURNAL-CODE: AX4. ENTRY-DATE: 940505. JOURNAL-SUBSET: M X. IM-DATE: 9407.