Identification of a Principal mRNA Species for Human 3 -Hydroxysteroid Dehydrogenase Isoform (AKR1C3) That Exhibits High Prostaglandin D2 11-Ketoreductase Activity

Abstract

Human 3alpha-hydroxysteroid dehydrogenase exists in four isoforms, which belong to the aldo-keto reductase (AKR) superfamily and are named AKR1C1-AKR1C4. The properties of AKR1C3 have not been fully characterized compared to the other isoforms. In addition, a cDNA that shows more than 99% homology with AKR1C3 cDNA has been cloned from human myeloblasts. We have here expressed and purified a recombinant enzyme (designated as DBDH) from this cDNA. DBDH oxidized xenobiotic alicyclic alcohols and 3alpha- or 17beta-hydroxy-5beta-androstanes, and catalyzed the reversible conversion between prostaglandin D2 and 9alpha,11beta-prostaglandin F2 more efficiently than that of 3alpha- or 17beta-hydroxysteroids:the respective Km values were 0.6 and 6.8 microM, and kcat/Km values were about 1,000 min-1.mM-1. Anti-inflammatory drugs highly inhibited the enzyme. The recombinant AKR1C3 prepared by site-directed mutagenesis of DBDH also showed the same properties as the wild-type DBDH. Analyses of expression of mRNAs for DBDH and AKR1C3 by reverse transcription-PCR indicated that only one mRNA species for DBDH is expressed in 33 human specimens of liver, kidney, lung, brain, heart, spleen, adrenal gland, small intestine, placenta, prostate, and testis. These results suggest that AKR1C3 acts as prostaglandin D2 11-ketoreductase, and that its principal gene in the human has a coding region represented by DBDH cDNA.

Close kinship of human 20α‐hydroxysteroid dehydrogenase gene with three aldo‐keto reductase genes

“…The activities to oxidize these synthetic substrates were inhibited by bile acids (data not shown), similarly to the previous report with BABP puri®ed from the liver (Hara et al 1996). On the other hand, PGFS shows prominent PGD 2 11-ketoreductase activity to reduce PGD 2 and to oxidize 9a, 11b-PGF 2 (Matsuura et al 1998;Suzuki-Yamamoto et al 1999). DD4 possessed 3a-HSD activity, such as the reduction of androstanolone and the oxidation of dihydroandrosterone and bile acids, including chenodeoxycholic acid.…”

An indomethacin analogue, N-(4-chlorobenzoyl)-melatonin, is a selective inhibitor of aldo-keto reductase 1C3 (type 2 3α-HSD, type 5 17β-HSD, and prostaglandin F synthase), a potential target for the treatment of hormone dependent and hormone independent malignancies

“…This effect is reflected by the lower K I for indomethacin observed for both the uncompetitive inhibition of PQ reduction and the competitive inhibition of testosterone oxidation as compared to the higher K I value observed for the competitive inhibition of Δ 4 -androstene-3,17-dione reduction. Inhibition of the AKR1C3-mediated formation of the PGF 2 isomers by indomethacin and its analogues may occur through either one or both of these complexes as these reactions have catalytic efficiencies that are intermediate between the reduction of PQ and the reduction of Δ 4 -androstene-3,17-dione [10].…”

“…Indomethacin methyl ester, which could only be tested up to 20 μM because its UV absorbance interfered with the assay at higher concentrations, effectively inhibited only AKR1C3 and had no effect on PQ reduction by the other AKR1C enzymes at the concentrations tested. Previously, Matsuura et al [10] had shown that indomethacin had high affinity for AKR1C3, while Hara et al [26] showed that indomethacin was a relatively weak inhibitor of AKR1C1 and AKR1C2. However, these studies used widely varied concentrations of substrate relative to the K M of the respective enzymes, making the results difficult to compare across isoform.…”

“…AKR1C3 also plays an important role in the biosynthesis of prostaglandins, catalyzing the formation of prostaglandin (PG) F 2α and 9α,11β-PGF 2 from PGH 2 and PGD 2 , respectively [9,10]. Of its endogenously relevant substrates, AKR1C3 has the highest catalytic activity for the reduction of PGD 2 [9;10].…”

Introduction and Overview of the Aldo-Keto Reductase Superfamily

“…AKRs that have hydroxysteroid dehydrogenase activity can either form or eliminate active steroid hormone in target tissues and therefore may regulate the occupancy and ^raws-activation of steroid receptors (54). A similar case could be made for AKRs that have prostaglandin reductase activity since they may regulate ligand access to PPARy receptors (55). This area needs further attention.…”