Human prostatic steroid 5 alpha-reductase isoforms--a comparative study of selective inhibitors

C Iehlé, S Délos, O Guirou, R Tate, J P Raynaud, P M Martin

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Abstract

The present study describes the independent expression of the type 1 and 2 isoforms of human 5 alpha-reductase in the baculovirus-directed insect cell expression system and the selectivity of their inhibition. The catalytic properties and kinetic parameters of the recombinant isozymes were consistent with published data. The type 1 isoform displayed a neutral (range 6-8) pH optimum and the type 2 isoform an acidic (5-6) pH optimum. The type 2 isoform had higher affinity for testosterone than did the type 1 isoform (Km = 0.5 and 2.9 microM, respectively). Finasteride and turosteride were selective inhibitors of the type 2 isoform (Ki (type 2) = 7.3 and 21.7 nM compared to Ki (type 1) = 108 and 330 nM, respectively). 4-MA and the lipido-sterol extract of Serenoa repens (LSESr) markedly inhibited both isozymes (Ki (type 1) = 8.4 nM and 7.2 micrograms/ml, respectively; Ki (type 2) = 7.4 nM and 4.9 micrograms/ml, respectively). The three azasteroids were competitive inhibitors vs substrate, whereas LSESr displayed non-competitive inhibition of the type 1 isozyme and uncompetitive inhibition of the type 2 isozyme. These observations suggest that the lipid component of LSESr might be responsible for its inhibitory effect by modulating the membrane environment of 5 alpha-reductase. Partially purified recombinant 5 alpha-reductase type 1 activity was preserved by the presence of lipids indicating that lipids can exert either stimulatory or inhibitory effects on human 5 alpha-reductase.
LanguageEnglish
Pages273-279
Number of pages7
JournalJournal of Steroid Biochemistry and Molecular Biology
Volume54
Issue number5-6
DOIs
Publication statusPublished - 1995

Fingerprint

3-Oxo-5-alpha-Steroid 4-Dehydrogenase
Cholestenone 5 alpha-Reductase
Protein Isoforms
Isoenzymes
Sterols
Lipids
Azasteroids
Finasteride
Baculoviridae
Kinetic parameters
Insects
Membranes
Substrates

Keywords

  • animals
  • azasteroids
  • Cholestenone 5 alpha-Reductase
  • dihydrotestosterone
  • enzyme activation
  • enzyme inhibitors
  • finasteride
  • insects
  • isoenzymes
  • oxidoreductases
  • prostate
  • recombinant proteins
  • transfection

Cite this

Iehlé, C ; Délos, S ; Guirou, O ; Tate, R ; Raynaud, J P ; Martin, P M. / Human prostatic steroid 5 alpha-reductase isoforms--a comparative study of selective inhibitors. In: Journal of Steroid Biochemistry and Molecular Biology . 1995 ; Vol. 54, No. 5-6. pp. 273-279.
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Human prostatic steroid 5 alpha-reductase isoforms--a comparative study of selective inhibitors. / Iehlé, C; Délos, S; Guirou, O; Tate, R; Raynaud, J P; Martin, P M.

In: Journal of Steroid Biochemistry and Molecular Biology , Vol. 54, No. 5-6, 1995, p. 273-279.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Human prostatic steroid 5 alpha-reductase isoforms--a comparative study of selective inhibitors

AU - Iehlé, C

AU - Délos, S

AU - Guirou, O

AU - Tate, R

AU - Raynaud, J P

AU - Martin, P M

PY - 1995

Y1 - 1995

N2 - The present study describes the independent expression of the type 1 and 2 isoforms of human 5 alpha-reductase in the baculovirus-directed insect cell expression system and the selectivity of their inhibition. The catalytic properties and kinetic parameters of the recombinant isozymes were consistent with published data. The type 1 isoform displayed a neutral (range 6-8) pH optimum and the type 2 isoform an acidic (5-6) pH optimum. The type 2 isoform had higher affinity for testosterone than did the type 1 isoform (Km = 0.5 and 2.9 microM, respectively). Finasteride and turosteride were selective inhibitors of the type 2 isoform (Ki (type 2) = 7.3 and 21.7 nM compared to Ki (type 1) = 108 and 330 nM, respectively). 4-MA and the lipido-sterol extract of Serenoa repens (LSESr) markedly inhibited both isozymes (Ki (type 1) = 8.4 nM and 7.2 micrograms/ml, respectively; Ki (type 2) = 7.4 nM and 4.9 micrograms/ml, respectively). The three azasteroids were competitive inhibitors vs substrate, whereas LSESr displayed non-competitive inhibition of the type 1 isozyme and uncompetitive inhibition of the type 2 isozyme. These observations suggest that the lipid component of LSESr might be responsible for its inhibitory effect by modulating the membrane environment of 5 alpha-reductase. Partially purified recombinant 5 alpha-reductase type 1 activity was preserved by the presence of lipids indicating that lipids can exert either stimulatory or inhibitory effects on human 5 alpha-reductase.

AB - The present study describes the independent expression of the type 1 and 2 isoforms of human 5 alpha-reductase in the baculovirus-directed insect cell expression system and the selectivity of their inhibition. The catalytic properties and kinetic parameters of the recombinant isozymes were consistent with published data. The type 1 isoform displayed a neutral (range 6-8) pH optimum and the type 2 isoform an acidic (5-6) pH optimum. The type 2 isoform had higher affinity for testosterone than did the type 1 isoform (Km = 0.5 and 2.9 microM, respectively). Finasteride and turosteride were selective inhibitors of the type 2 isoform (Ki (type 2) = 7.3 and 21.7 nM compared to Ki (type 1) = 108 and 330 nM, respectively). 4-MA and the lipido-sterol extract of Serenoa repens (LSESr) markedly inhibited both isozymes (Ki (type 1) = 8.4 nM and 7.2 micrograms/ml, respectively; Ki (type 2) = 7.4 nM and 4.9 micrograms/ml, respectively). The three azasteroids were competitive inhibitors vs substrate, whereas LSESr displayed non-competitive inhibition of the type 1 isozyme and uncompetitive inhibition of the type 2 isozyme. These observations suggest that the lipid component of LSESr might be responsible for its inhibitory effect by modulating the membrane environment of 5 alpha-reductase. Partially purified recombinant 5 alpha-reductase type 1 activity was preserved by the presence of lipids indicating that lipids can exert either stimulatory or inhibitory effects on human 5 alpha-reductase.

KW - animals

KW - azasteroids

KW - Cholestenone 5 alpha-Reductase

KW - dihydrotestosterone

KW - enzyme activation

KW - enzyme inhibitors

KW - finasteride

KW - insects

KW - isoenzymes

KW - oxidoreductases

KW - prostate

KW - recombinant proteins

KW - transfection

U2 - 10.1016/0960-0760(95)00134-L

DO - 10.1016/0960-0760(95)00134-L

M3 - Article

VL - 54

SP - 273

EP - 279

JO - Journal of Steroid Biochemistry and Molecular Biology

T2 - Journal of Steroid Biochemistry and Molecular Biology

JF - Journal of Steroid Biochemistry and Molecular Biology

SN - 0960-0760

IS - 5-6

ER -