Publications

• Sex hormone metabolism in prostate cancer cells during transition to an androgen-independent state.

  Haerkoenen P., Toern S., Kurkela R., Porvari K., Pulkka A., Lindfors A., Isomaa V., Vihko P.

  The progression of prostate cancer during androgen deprivation therapy is a serious clinical problem. Little is known, however, about the mechanisms behind the transition of the disease to an androgen-independent stage. In the present report, we provide evidence of substantial changes in both estr ... >> More

  The progression of prostate cancer during androgen deprivation therapy is a serious clinical problem. Little is known, however, about the mechanisms behind the transition of the disease to an androgen-independent stage. In the present report, we provide evidence of substantial changes in both estrogen and androgen metabolism during the transition of cultured prostate cancer LNCaP (lymph node carcinoma of the prostate) cells. The results of enzyme activity measurements performed using HPLC suggest that, related to the transition, there exists a remarkable decrease in the oxidative 17 beta-hydroxysteroid dehydrogenase (17HSD) activity, whereas the reductive 17HSD activity seems to increase. Relative quantitative RT-PCR revealed that the decrease in oxidative activity largely coincided with the remarkable decrease in the expression of the HSD17B2 gene. Furthermore, the present data suggest that the observed increasing activity of 17HSD type 7 could lead to the increased intracellular production of 17 beta-estradiol during disease progression. This was supported by the cDNA microarray screening results, which showed a considerable overexpression of several estrogen up-regulated genes in the LNCaP cell line variant that represents progressive prostate cancer. Because 17HSDs critically contribute to the control of bioavailability of active sex steroid hormones locally in the prostate, the observed variation in intraprostatic 17HSD activity might be predicted to be crucially involved in the regulation of growth and function of the organ. << Less

  J. Clin. Endocrinol. Metab. 88:705-712(2003) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Multiple catalytic activities of human 17beta-hydroxysteroid dehydrogenase type 7 respond differently to inhibitors.

  Ferrante T., Adinolfi S., D'Arrigo G., Poirier D., Daga M., Lolli M.L., Balliano G., Spyrakis F., Oliaro-Bosso S.

  Cholesterol biosynthesis is a multistep process in mammals that includes the aerobic removal of three methyl groups from the intermediate lanosterol, one from position 14 and two from position 4. During the demethylations at position 4, a 3-ketosteroid reductase catalyses the conversion of both 4- ... >> More

  Cholesterol biosynthesis is a multistep process in mammals that includes the aerobic removal of three methyl groups from the intermediate lanosterol, one from position 14 and two from position 4. During the demethylations at position 4, a 3-ketosteroid reductase catalyses the conversion of both 4-methylzymosterone and zymosterone to 4-methylzymosterol and zymosterol, respectively, restoring the alcoholic function of lanosterol, which is also maintained in cholesterol. Unlike other eukaryotes, mammals also use the same enzyme as an estrone reductase that can transform estrone (E1) into estradiol (E2). This enzyme, named 17β-hydroxysteroid dehydrogenase type 7 (HSD17B7), is therefore a multifunctional protein in mammals, and one that belongs to both the HSD17B family, which is involved in steroid-hormone metabolism, and to the family of post-squalene cholesterol biosynthesis enzymes. In the present study, a series of known inhibitors of human HSD17B7's E1-reductase activity have been assayed for potential inhibition against 3-ketosteroid reductase activity. Surprisingly, the assayed compounds lost their inhibition activity when tested in HepG2 cells that were incubated with radiolabelled acetate and against the recombinant overexpressed human enzyme incubated with 4-methylzymosterone (both radiolabelled and not). Preliminary kinetic analyses suggest a mixed or non-competitive inhibition on the E1-reductase activity, which is in agreement with Molecular Dynamics simulations. These results raise questions about the mechanism(s) of action of these possible inhibitors, the enzyme dynamic regulation and the interplay between the two activities. << Less

  Biochimie 170:106-117(2020) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• Human cytosolic 3alpha-hydroxysteroid dehydrogenases of the aldo-keto reductase superfamily display significant 3beta-hydroxysteroid dehydrogenase activity: implications for steroid hormone metabolism and action.

  Steckelbroeck S., Jin Y., Gopishetty S., Oyesanmi B., Penning T.M.

  The source of NADPH-dependent cytosolic 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity is unknown to date. This important reaction leads e.g. to the reduction of the potent androgen 5alpha-dihydrotestosterone (DHT) into inactive 3beta-androstanediol (3beta-Diol). Four human cytosolic aldo ... >> More

  The source of NADPH-dependent cytosolic 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity is unknown to date. This important reaction leads e.g. to the reduction of the potent androgen 5alpha-dihydrotestosterone (DHT) into inactive 3beta-androstanediol (3beta-Diol). Four human cytosolic aldo-keto reductases (AKR1C1-AKR1C4) are known to act as non-positional-specific 3alpha-/17beta-/20alpha-HSDs. We now demonstrate that AKR1Cs catalyze the reduction of DHT into both 3alpha- and 3beta-Diol (established by (1)H NMR spectroscopy). The rates of 3alpha-versus 3beta-Diol formation varied significantly among the isoforms, but with each enzyme both activities were equally inhibited by the nonsteroidal anti-inflammatory drug flufenamic acid. In vitro, AKR1Cs also expressed substantial 3alpha[17beta]-hydroxysteroid oxidase activity with 3alpha-Diol as the substrate. However, in contrast to the 3-ketosteroid reductase activity of the enzymes, their hydroxysteroid oxidase activity was potently inhibited by low micromolar concentrations of the opposing cofactor (NADPH). This indicates that in vivo all AKR1Cs will preferentially work as reductases. Human hepatoma (HepG2) cells (which lack 3beta-HSD/Delta(5-4) ketosteroid isomerase mRNA expression, but express AKR1C1-AKR1C3) were able to convert DHT into 3alpha- and 3beta-Diol. This conversion was inhibited by flufenamic acid establishing the in vivo significance of the 3alpha/3beta-HSD activities of the AKR1C enzymes. Molecular docking simulations using available crystal structures of AKR1C1 and AKR1C2 demonstrated how 3alpha/3beta-HSD activities are achieved. The observation that AKR1Cs are a source of 3beta-tetrahydrosteroids is of physiological significance because: (i) the formation of 3beta-Diol (in contrast to 3alpha-Diol) is virtually irreversible, (ii) 3beta-Diol is a pro-apoptotic ligand for estrogen receptor beta, and (iii) 3beta-tetrahydrosteroids act as gamma-aminobutyric acid type A receptor antagonists. << Less

  J. Biol. Chem. 279:10784-10795(2004) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• Human cytosolic hydroxysteroid dehydrogenases of the aldo-ketoreductase superfamily catalyze reduction of conjugated steroids: implications for phase I and phase II steroid hormone metabolism.

  Jin Y., Duan L., Lee S.H., Kloosterboer H.J., Blair I.A., Penning T.M.

  Aldo-ketoreductase 1C (AKR1C) enzymes catalyze the NADPH-dependent reduction of ketosteroids to hydroxysteroids. They are Phase I metabolizing enzymes for natural and synthetic steroid hormones. They convert 5alpha-dihydrotestosterone (Dht, potent androgen) to 3alpha/beta-androstanediols (inactive ... >> More

  Aldo-ketoreductase 1C (AKR1C) enzymes catalyze the NADPH-dependent reduction of ketosteroids to hydroxysteroids. They are Phase I metabolizing enzymes for natural and synthetic steroid hormones. They convert 5alpha-dihydrotestosterone (Dht, potent androgen) to 3alpha/beta-androstanediols (inactive androgens) and the prodrug tibolone (Tib) to estrogenic 3alpha/beta-hydroxytibolones. Herein we demonstrate for the first time that human AKR1C enzymes (AKR1C1-4) are able to reduce conjugated steroids such as Dht-17beta-glucuronide (DhtG), Dht-17beta-sulfate (DhtS), and Tib-17beta-sulfate (TibS). Product identities were characterized by liquid chromatography-mass spectrometry, and kinetic parameters of the reactions were determined. The product profile of the reduction of each steroid conjugate by the individual AKR1C isoform was similar to that of the corresponding free steroid except for the reduction of DhtG catalyzed by AKR1C2, where a complete inversion in stereochemical preference to 3beta-reduction (with DhtG) from 3alpha-reduction (with Dht and DhtS) was observed. The catalytic efficiency of 3-keto reduction was modestly affected by the presence of a 17-sulfate group but severely impaired by the presence of a 17-glucuronide group for AKR1C1-3 isoforms. AKR1C4, however, showed superior catalytic efficiencies versus the other isoforms, and those were unaffected by steroid conjugation. Our findings provide evidence for alternative pathways of steroid metabolism where the phase I reaction (reduction) occurs after the phase II reaction (conjugation). Specifically, it is indicated that Dht is metabolized to its metabolite 3alpha-androstanediol-17-glucuronide via the previously unrecognized "conjugation pathway" involving the sequential reactions of UGT2B17 and AKR1C4 in liver but via the conventional "reduction pathway" involving the sequential reactions of AKR1C2 and UGT2B15/17 in prostate. << Less

  J. Biol. Chem. 284:10013-10022(2009) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.