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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pathways of testosterone metabolism in tissue slices and cell suspensions of human benign hyperplastic prostate (BPH) tissue and human prostate cancer cell lines (DU145, HPC-36M, PC-3/MA2 and LNCaP) were investigated. Thin layer chromatography analysis was used to identify the following tritiated metabolites: testosterone, 5 alpha-dihydrostestosterone (DHT), 5 alpha-androstane-3 alpha/3 beta-17 beta-diol (androstanediols), 4-androstene-3,17-dione (androstenedione) and 5 alpha-androstanedione. The predominant pathway for testosterone metabolism in BPH was via 5 alpha-reductase producing 5 alpha-dihydrotestosterone (71% and 75% total metabolites in slices and suspensions incubated for 24 h, respectively). The cancer cell lines DU145 and HPC-36M resembled BPH by metabolizing testosterone predominantly to DHT (68% and 82% total metabolites, respectively), although the rate of metabolism was much lower in the cell lines (0.099 and 0.05 pmol testosterone/mg protein/h in DU145 and HPC-36M) compared to the BPH cell suspensions (6.4 pmol testosterone/mg protein/h). In contrast, PC-3/MA2 contained high 17 beta-HSD activity forming large amounts of 4-androstene-3,17-dione (84% total metabolites), converting testosterone at a rate faster (12.8 pmol testosterone/mg protein/h) than the BPH cell suspensions. LNCaP rapidly converted testosterone exclusively to a glucuronide conjugate (7.4 pmol testosterone/mg protein/h), although after incubation with [3H]-4-androstene-3,17-dione, 5 alpha-reductase activity was demonstrated. LNCaP was the only cell line whose growth and colony-forming ability was stimulated by testosterone and DHT. BPH and all the cell lines tested had 5 alpha-reductase activity, but only the prostate tissue and the cell lines DU145 and HPC-36M converted testosterone predominantly to DHT.
J Steroid Biochem Mol Biol 1994 Aug
PMID:Comparison of testosterone metabolism in benign prostatic hyperplasia and human prostate cancer cell lines in vitro. 751 39

This study reports that, in contrast to previous findings, basic fibroblast growth factor (FGF-2) stimulates immature Leydig cell steroidogenesis in the absence of luteinizing hormone (LH). Heparan sulphate proteoglycans (HSPGs) are essential for this action of FGF-2 and the data suggest that HSPG/FGF-2 interactions have a significant role in the maintenance of immature Leydig cell steroidogenesis. Culture conditions were established for the maintenance of immature rat Leydig cells steroidogenesis in vitro for at least 2 days. Under these conditions the effect of exposure to FGF-2 at doses ranging from 0.1-10 ng/ml was shown to cause a significant stimulation of basal, but not LH-stimulated, 5 alpha-androstane 3 alpha,17 beta-diol production over 24h in culture. This stimulatory action on basal steroidogenesis is mediated through HSPG, as it was blocked by the addition of heparin (100 micrograms/ml), sodium chlorate (25mM) and protamine sulphate (5 micrograms/ml). These data demonstrate the involvement of HSPG in regulating FGF-2 action on Leydig cells and a potential role for Leydig cell HSPG in mediating paracrine regulatory actions of other heparin binding growth factors.
J Steroid Biochem Mol Biol 1995 Sep
PMID:Requirement for heparan sulphate proteoglycans to mediate basic fibroblast growth factor (FGF-2)-induced stimulation of Leydig cell steroidogenesis. 757 6

LNCaP, a human prostate cancer cell line, metabolizes testosterone into a variety of 5 alpha-reduced C19 steroids, such as dihydrotestosterone (DHT), androstane-3 alpha, 17 beta-diol (3 beta, 17 beta-DIOL), and androsterone (ADT). Recent reports also suggest that 5 alpha-reduced C19 steroid glucuronides can be detected in the medium. The purpose of this work was to characterize by liquid chromatograph ion spray mass spectroscopy (LCMS) the metabolites formed by LNCaP during incubation with testosterone and its 5 alpha-reduced C19 steroids. Time course studies using 10 nM labeled testosterone, 3 alpha-DIOL, 3 beta-DIOL, or ADT showed that a large proportion of polar steroids were produced by LNCaP. Identification of metabolites produced by LNCaP was carried out by LCMS using 1 microM substrates. Analysis of testosterone metabolism indicated that testosterone glucuronide was formed at 77 +/- 2% after 96 h of incubation. Using DHT as substrate, 3 alpha-DIOL-G and DHT-G were the major metabolites, accounting for 46 +/- 4% and 38 +/- 3%, respectively, of the total radioactivity in the medium; ADT-G accounted for 8 +/- 1%. Further analysis by LCMS also indicated that the glucuronide group in 3 alpha-DIOL-G was at position 17-carbon, 3 alpha-DIOL-G (86 +/- 3%) was the prominent metabolite formed from 3 alpha-DIOL, a minor product was detected at 7 +/- 1% and identified by mass spectrometry to correspond to a trihydroxylated C19 steroid.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1995 Feb
PMID:Glucuronosyltransferase activity in human cancer cell line LNCaP. 776 24

The structures of cDNA clones encoding four members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family were characterized. The rat type I, type II and the novel type IV are genuine NAD+/H-dependent 3 beta-HSD isoenzymes. On the other hand, the liver-specific type III protein is a specific 3-keto-reductase (3-KSR) that catalyzes the conversion of 5 alpha-androstane-3-one-17 beta-ol (DHT) and 5 alpha-androstane 3,17-dione (A-dione) into their 3 beta-hydroxy metabolites. The aim of the present study was to further characterize the enzymatic properties of rat types I, III and IV, especially their role in the formation and degradation of DHT after transient expression in intact human HeLa cervical carcinoma, JEG-3 choriocarcinoma or SW-13 adrenal cortex adenocarcinoma cells in culture. The expressed type III 3-KSR in intact HeLa cells catalyzed the reduction of DHT into 3 beta-diol, whereas expression of type I 3 beta-HSD in these cell lines had no significant effect on the basal conversion of DHT into 3 beta-diol, but it did increase the formation of DHT from 3 beta-diol. A-dione is the predominant product obtained when DHT and 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) are used as substrates in intact JEG-3 and SW-13 cells transfected with rat type I 3 beta-HSD. Furthermore, this predominant 17 beta-HSD activity was also observed in SW-13 cells transfected with the novel rat type IV 3 beta-HSD. The predominance of this 'secondary' 17 beta-HSD activity is also reflected in HeLa cells transfected with type I 3 beta-HSD by the deduced predominant pathway 3 beta-diol-->DHT-->5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol)-->androsterone (ADT), in which formation of 3 alpha-HSD activity of HeLa cells, whereas the other reactions are catalyzed by the type I 3 beta-HSD isoenzyme. This observation thus demonstrates that rat type I 3 beta-HSD may also catalyze the conversion of 3 alpha-diol into ADT through its intrinsic 17 beta-HSD activity. The predominant metabolic pathways observed in the present study could be attributed to preponderant bioavailability of NAD+ and NADPH in the intact transfected cells used.
Mol Cell Endocrinol 1994 Jul
PMID:Formation and degradation of dihydrotestosterone by recombinant members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase family. 795 95

Patients bearing macrocysts of the breast are at higher risk of later developing cancer. The fluid filling the cysts (breast cysts fluid, BCF) contains unusual amounts of steroid conjugates, first androgen and estrogen sulfates. Measuring BCF cations (K+,Na+) allows categorization of cysts into two major subsets (type I and type II) that are associated with a different degree and/or turnover of apocrine metaplastic cells in the lining epithelium. Type I cysts (high K+/Na+ ratio) accumulate hugh amounts of dehydroepiandrosterone sulfate, estrone sulfate, androstane-3 alpha,17 beta-diol glucuronide, androsterone glucuronide and contain more testosterone and dihydrotestosterone than type II. Conversely, type II cysts (low K+/Na+ ratio) contain more progesterone and pregnenolone. A cohort study was started in 1983 at the Cancer Prevention Center, Ravenna, Italy, with the aim of evaluating the relationships between the biochemistry of BCF and the incidence of breast cancer in women with gross cystic disease (GCD) of the breast. The bimodal distribution of the cationic pattern has been confirmed from data obtained in 798 patients aspirated. The risk of cyst relapse was significantly higher among women with type I cysts or with multiple cysts at presentation. Twelve incident cases of breast cancer have been diagnosed among women whose BCF was categorized. Eleven out of 12 cases had type I or multiple cysts. The cumulative incidence of breast cancer among patients bearing type I cysts was 2.5%. We conclude that women with GCD bearing type I cysts have an increased breast cancer risk when compared with the counterpart bearing type II cysts or the general population.
J Steroid Biochem Mol Biol 1994 Jun
PMID:Steroid biochemistry and categorization of breast cyst fluid: relation to breast cancer risk. 804 97

NADPH-dependent 3 alpha/beta-hydroxysteroid dehydrogenase (3 alpha/beta-HSD) was purified to apparent homogeneity from testicular cytosol of mature pigs. The purified enzyme catalyzes the conversion of 5 alpha-dihydrotestosterone (5 alpha-DHT) to both 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol. The molecular weight of the enzyme was estimated to be 31 kDa by SDS-polyacrylamide gel electrophoresis and 40 kDa by gel filtration chromatography indicating that the native 3 alpha/beta-HSD is a monomer. The isoelectric point of the purified enzyme was found to be 6.2 by density gradient isoelectric focusing and 6.4 by chromatofocusing. The enzyme reduced both 5 alpha- and 5 beta-DHT, 5 alpha- and 5 beta-dihydroprogesterone, 5 alpha- and 5 beta-dihydrocortisol, prostaglandin E2, 13,14-dihydro-15-keto-prostaglandin E2 and 13,14-dihydro-15-keto-prostaglandin F2 alpha. Moreover, the enzyme caused rapid reduction of other carbonyl compounds including aldehydes, ketones and quinones. The rates of reduction of these compounds are fast relative to the rates of reduction of steroids and prostaglandins. The purified enzyme was inhibited by AgNO3, SH-reagent, quercetin, hexesterol, stilbestrol, disulfiram and divalent cation such as Cu2+, Hg2+ and Cd2+. The two enzymes show certain similarities (e.g. molecular weight, cross-reactivity to a common antibody) and certain striking differences (e.g. pI, effects of various inhibitors and greater enzyme activity towards steroids (neonatal form) or prostaglandins (mature form). Reasons are give for suggesting that these enzymes are closely related to carbonyl reductase.
J Steroid Biochem Mol Biol 1994 Feb
PMID:Purification and characterization of 3 alpha/beta-hydroxysteroid dehydrogenase from mature porcine testicular cytosol. 814 2

The enzyme 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta HSD) is essential for the biosynthesis of all steroid hormones. The enzyme catalyzes the conversion of delta 5-3 beta-hydroxysteroids to delta 4-3-ketosteroids. We report the isolation of a novel mouse 3 beta HSD cDNA, 3 beta HSD IV, and describe the tissue-specific expression of its mRNA, the enzyme characteristics of the 3 beta HSD IV protein, and the structural and functional relationships it has to other 3 beta HSD isoforms previously characterized in the mouse and rat. The predicted amino acid sequence of mouse 3 beta HSD IV is 77% and 73% identical to that of mouse 3 beta HSD I and III, respectively. Comparison of the nucleotide and amino acid sequences of the four isoforms characterized to date show that 3 beta HSD IV is more distantly related to I, II, and III than these three forms are to each other. 3 beta HSD IV mRNA is only expressed in mouse kidney. In situ hybridization of mouse kidney indicates that expression is found only in the cortex and appears to be associated with the proximal tubules. Transiently expressed 3 beta HSD IV protein could not convert the delta 5-3 beta-hydroxysteroids, pregnenolone or dehydroepiandrosterone, to their respective delta 4-3-ketosteroids, progesterone or androstenedione, nor did it have the capacity to convert 5 alpha-androstane-3 beta, 17 beta-diol to dihydrotestosterone, characteristic enzymatic activities of expressed mouse 3 beta HSD I and III. 3 beta HSD IV could only catalyze the conversion of dihydrotestosterone to 5 alpha-androstanediol in the presence of the cofactor NADPH. Thus, 3 beta HSD IV is a 3-ketosteroid reductase rather than a 3 beta-hydroxysteroid dehydrogenase/isomerase despite its homology to the other members of the 3 beta HSD family. Mouse 3 beta HSD IV is functionally and structurally most closely related to rat 3 beta HSD III, an isoform expressed predominantly in male rat liver.
Mol Endocrinol 1993 Dec
PMID:A novel mouse kidney 3 beta-hydroxysteroid dehydrogenase complementary DNA encodes a 3-ketosteroid reductase instead of a 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase. 814 63

Turosteride [FCE 26073; 1-(4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carbonyl)-1,3- diisopropylurea] is a novel inhibitor of 5 alpha-reductase, the enzyme responsible for the conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). The compound caused inhibition of rat and human prostatic enzymes, with IC50 values of 55 and 53 nM, respectively. In addition, turosteride did not show any relevant binding affinity to the rat prostate androgen receptor (IC50 84 microM; relative binding affinity 0.004% of DHT). The endocrine effects of turosteride were evaluated in adult male rats, treated orally at daily doses of 3, 10 and 30 mg/kg for 20 days. At these doses, the compound reduced the ventral prostate weight by 10, 33 and 42% and the intraprostatic total DHT content by 61, 74 and 78%, respectively, whereas no change in the intraprostatic content of T was observed. Turosteride caused a 40% reduction of serum DHT levels which, however, did not reach statistical significance, whereas serum T levels were similar to control animals. No effect on serum luteinizing hormone or prolactin was observed. These results indicate that the antiprostatic effect of turosteride in the adult rat is related to inhibition of the conversion of T to DHT. However, at variance with other 5 alpha-reductase inhibitors (e.g. finasteride), turosteride caused a decrease in prostatic DHT not associated with a secondary increase in T content. This peculiarity of turosteride may represent an improvement of the compound over other inhibitors.
J Steroid Biochem Mol Biol 1993 Nov
PMID:Hormonal effects of turosteride, a 5 alpha-reductase inhibitor, in the rat. 824 Sep 76

Androst-5-ene-3 beta,17 beta-diol (ADIOL) and 5 alpha-androstane-3 beta,17 beta-diol (5 alpha A), which are metabolites of dehydroepiandrosterone and dihydrotestosterone, are known to have estrogenic properties. This study reevaluates the estrogenic effects of ADIOL and 5 alpha A in MCF-7 cells and demonstrates additionally androgen-like inhibitory properties of these compounds in human hormone-dependent mammary cancer cells. ADIOL and 5 alpha A (10-100 nM) stimulate the proliferation of estrogen-sensitive MCF-7 cells. Binding assays with the estrogen receptor and inhibition of stimulation with the antiestrogen tamoxifen support the involvement of the estrogen receptor. On the other hand, the mammary cancer cell line MFM-223 is strongly inhibited by ADIOL and 5 alpha A in the same concentration range. This cell line is androgen receptor positive and is inhibited by androgens, but unresponsive to estrogens and progestins. The inhibitory effects of ADIOL and 5 alpha A in MFM-223 cells are mediated by the androgen receptor as demonstrated by receptor studies and competition experiments with hormone antagonists. ADIOL and 5 alpha A thus possess estrogen- and androgen-like properties and can stimulate or inhibit proliferation of human mammary cancer cells. The reactions of mammary cancer cells to these steroids depend on the receptor content and the growth properties of the individual cell line.
J Steroid Biochem Mol Biol 1993 Nov
PMID:Estrogen and androgen receptor mediated stimulation and inhibition of proliferation by androst-5-ene-3 beta,17 beta-diol in human mammary cancer cells. 824 Sep 82

The role of brain cytochrome P450 (P450) in regulating the levels of the potent anesthetic steroid 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha-OH-DHP) has been investigated. By analogy with the elimination of androgen from its target tissues, we present evidence that it is 3 beta-hydroxy-5 alpha-pregnan-20-one (3 beta-OH-DHP) and not 3 alpha-OH-DHP that represents the major pathway for the formation of more polar metabolites and thus the elimination of the 5 alpha-reduced metabolites of progesterone from target tissues. No polar metabolites were formed when 3 alpha-OH-DHP was incubated with microsomal fractions prepared from rat brain, but 3 beta-OH-DHP was hydroxylated at the 6 alpha- and 7 alpha-positions. These 3 beta-diols were not formed to any detectable extent in the liver or kidney but were formed in prostate, pituitary, brain, and breast. The highest catalytic activity, 512 nmol of products formed/g of tissue/hr, was found in the prostate. The corresponding rates in the pituitary, brain, and breast were 71.9, 28.1, and 6.7 nmol/g/hr, respectively. These hydroxylations were confirmed to be P450-catalyzed reactions by solubilization of the P450 from prostate, brain, and breast microsomes and reconstitution of the catalytic activity with NADPH-P450 reductase (EC 1.6.2.4) and lipid. Because 5 alpha-androstane-3 beta,17 beta-diol (3 beta-Adiol) has been shown to be a good substrate for prostate and brain P450, competition experiments were performed to determine whether the same form of P450 is involved in the elimination of 3 beta-Adiol and 3 beta-OH-DHP in the brain. These two substrates competed with each other for metabolism in microsomal fractions and in reconstitution experiments with P450 extracted from the brain or prostate. To test the hypothesis that the hydroxylation of 3 beta-OH-DHP represents a pathway for regulation of the level of 3 alpha-OH-DHP in the brain, the effect of inhibition of the hydroxylation of 3 beta-OH-DHP on the duration of 3 alpha-OH-DHP-induced anesthesia was examined. The nonanesthetic steroid 3 beta-Adiol was used as a competitive inhibitor of the metabolism of 3 beta-OH-DHP. The duration of anesthesia upon intravenous administration of 3 alpha-OH-DHP was increased by 33% when 3 beta-Adiol was coadministered.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Pharmacol 1993 Nov
PMID:Role of brain cytochrome P450 in regulation of the level of anesthetic steroids in the brain. 824 11


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