Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: HUMANGGP:014866 (AKR1C1)
 209 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human 20alpha-hydroxysteroid dehydrogenase (h20alpha-HSD; AKR1C1) catalyzes the transformation of progesterone (Prog) into 20alpha-hydroxy-progesterone (20alpha-OHProg). Although h20alpha-HSD shares 98% sequence identity with human type 3 3alpha-HSD (h3alpha-HSD3, AKR1C2), these two enzymes differ greatly in their activities. In order to explain these differences, we have solved the crystal structure of h20alpha-HSD in a ternary complex with NADP(+) and 20alpha-OHProg at 1.59A resolution. The steroid is stabilized by numerous hydrophobic interactions and a hydrogen bond between its O20 and the N(epsilon ) atom of His222. This new interaction prevents the formation of a hydrogen bond with the cofactor, as seen in h3alpha-HSD3 ternary complexes. By combining structural, direct mutagenesis and kinetic studies, we found that the H(222)I substitution decreases the K(m) value for the cofactor 95-fold. With these results, we hypothesize that the rotation of the lateral chain of His222 could be a mediating step between the transformation of Prog and the release of the cofactor. Moreover, crystal structure analysis and direct mutagenesis experiments lead us to identify a new residue involved in the binding of Prog. Indeed, the R(304)L substitution leads to a 65-fold decrease in the K(m) value for Prog reduction. We thus propose that Prog is maintained in a new steroid-binding site composed mainly of residues found in the carboxy-terminal region of the protein.
 ...
PMID:Human 20alpha-hydroxysteroid dehydrogenase: crystallographic and site-directed mutagenesis studies lead to the identification of an alternative binding site for C21-steroids. 1289 31

Progesterone plays an essential role in breast development and cancer formation. The local metabolism of progesterone may limit its interactions with the progesterone receptor (PR) and thereby act as a prereceptor regulator. Selective loss of AKR1C1, which encodes a 20alpha-hydroxysteroid dehydrogenase [20alpha-HSD (EC 1.1.1.149)], and AKR1C2, which encodes a 3alpha-hydroxysteroid dehydrogenase [3alpha-HSD (EC 1.1.1.52)], was found in 24 paired breast cancer samples as compared with paired normal tissues from the same individuals. In contrast, AKR1C3, which shares 84% sequence identity, and 5alpha-reductase type I (SRD5A1) were minimally affected. Breast cancer cell lines T-47D and MCF-7 also expressed reduced AKR1C1, whereas the breast epithelial cell line MCF-10A expressed AKR1C1 at levels comparable with those of normal breast tissues. Immunohistochemical staining confirmed loss of AKR1C1 expression in breast tumors. AKR1C3 and AKR1C1 were localized on the same myoepithelial and luminal epithelial cell layers. Suppression of ARK1C1 and AKR1C2 by selective small interfering RNAs inhibited production of 20alpha-dihydroprogesterone and was associated with increased progesterone in MCF-10A cells. Suppression of AKR1C1 alone or with AKR1C2 in T-47D cells led to decreased growth in the presence of progesterone. Overexpression of AKR1C1 and, to a lesser extent, AKR1C2 (but not AKR1C3) decreased progesterone-dependent PR activation of a mouse mammary tumor virus promoter in both prostate (PC-3) and breast (T-47D) cancer cell lines. We speculate that loss of AKR1C1 and AKR1C2 in breast cancer results in decreased progesterone catabolism, which, in combination with increased PR expression, may augment progesterone signaling by its nuclear receptors.
 ...
PMID:Selective loss of AKR1C1 and AKR1C2 in breast cancer and their potential effect on progesterone signaling. 1549 89

We examined expression and activity of steroid aldoketoreductase (AKR) 1C enzymes in adipose tissue in women. AKR1C1 (20alpha-hydroxysteroid dehydrogenase; 20alpha-HSD), AKR1C2 (3alpha-HSD-3), and AKR1C3 (17beta-HSD-5) are involved mainly in conversion of progesterone to 20alpha-hydroxyprogesterone and inactivation of dihydrotestosterone to 5alpha-androstane-3alpha,17beta-diol. Abdominal subcutaneous and omental adipose tissue biopsies were obtained during abdominal hysterectomies in seven women with low visceral adipose tissue (VAT) area and seven age- and total body fat mass-matched women with visceral obesity. Women with elevated VAT areas were characterized by significantly higher omental adipose tissue 20alpha-HSD and 3alpha-HSD-3 mRNA abundance compared with women with low VAT accumulations (1.4- and 1.6-fold differences, respectively; P < 0.05). Omental and subcutaneous adipose tissue 3alpha-HSD activities were significantly higher in women with high vs. low VAT areas (P < 0.05 for both comparisons). Total and visceral adiposities were positively associated with omental 20alpha-HSD mRNA level (r = 0.75, P < 0.003 for fat mass; r = 0.57, P < 0.04 for VAT area) and omental 3alpha-HSD-3 mRNA level (r = 0.68, P < 0.01 for fat mass; r = 0.74, P < 0.003 for VAT area). Enzyme activities in both depots were also positively correlated with adiposity measures. Omental adipose tissue enzyme expression and activity were positively associated with omental adipocyte size and LPL activity. In conclusion, mRNA abundance and activity of AKR1C enzymes in abdominal adipose tissue compartments are positive correlates of adiposity in women. Increased progesterone and/or dihydrotestosterone reduction in abdominal adipose tissue may impact locally on fat cell metabolism.
 ...
PMID:Expression and activity of steroid aldoketoreductases 1C in omental adipose tissue are positive correlates of adiposity in women. 1549 12

Endometrial cancer is the most common malignancy of the female genital tract. Its incidence correlates with prolonged estrogen stimulation unopposed by progesterone or synthetic progestins. Estrogen and progestin action is regulated at the pre-receptor level, by interconversion of active hormones (estradiol (E2), progesterone (P)) with their inactive counterparts (estrone (E1), 20alpha-hydroxyprogesterone (20alpha-OHP)) in target tissues. Expression of enzymes that control the ratio of E2 and P may thus play role in the disease process. We first confirmed that AKR1C1 (human 20alpha-hydroxysteroid dehydrogenase) in a cellular context inactivates P by forming 20alpha-OHP but does not catalyze the reverse reaction. We next examined the expression of AKR1C1 and AKR1C3 (type 5 17beta-hydroxysteroid dehydrogenase) in 16 paired specimens of endometrial cancer and adjacent normal endometrium. Quantification by isoform specific real-time PCR revealed higher expression of AKR1C1 in nine specimens and higher expression of AKR1C3 in four specimens of endometrial cancer. Importantly, upregulation of both enzymes in the same specimen was observed. Since AKR1C1 inactivates P its elevated expression in diseased endometrium may contribute to diminished protection by P, while elevated expression of AKR1C3 which forms E2 in vivo, may contribute to the enhanced estrogen action. It is suggested that the expression of AKR1C1 and AKR1C3 in endometrial cancer will govern the ratio of P:E2.
 ...
PMID:AKR1C1 and AKR1C3 may determine progesterone and estrogen ratios in endometrial cancer. 1633 60

Phytoestrogens are plant-derived, non-steroidal constituents of our diets. They can act as agonists or antagonists of estrogen receptors, and they can modulate the activities of the key enzymes in estrogen biosynthesis. Much less is known about their actions on the androgen and progesterone metabolizing enzymes. We have examined the inhibitory action of phytoestrogens on the key human progesterone-metabolizing enzyme, 20alpha-hydroxysteroid dehydrogenase (AKR1C1). This enzyme inactivates progesterone and the neuroactive 3alpha,5alpha-tetrahydroprogesterone, to form their less active counterparts, 20alpha-hydroxyprogesterone and 5alpha-pregnane-3alpha,20alpha-diol, respectively. We overexpressed recombinant human AKR1C1 in Escherichia coli, purified it to homogeneity, and examined the selected phytoestrogens as inhibitors of NADPH-dependent reduction of a common AKR substrate, 9,10-phenantrenequinone, and progesterone. The most potent inhibitors were 7-hydroxyflavone, 3,7-dihydroxyflavone and flavanone naringenin with IC(50) values in the low microM range. Docking of the flavones in the active site of AKR1C1 revealed their possible binding modes, in which they are sandwiched between the Leu308 and Trp227 of AKR1C1.
 ...
PMID:Phytoestrogens as inhibitors of the human progesterone metabolizing enzyme AKR1C1. 1696 2

We examined 5alpha-dihydrotestosterone (5alpha-DHT) inactivation and the expression of several steroid-converting enzymes with a focus on aldoketoreductases 1C (AKR1C), especially AKR1C2, in abdominal adipose tissue in men. AKR1C2 is mainly involved in the conversion of the potent androgen 5alpha-DHT to its inactive forms 5alpha-androstane-3alpha/beta,17beta-diol (3alpha/beta-diol). Subcutaneous (s.c.) and omental (Om) adipose tissue biopsies were obtained from 21 morbidly obese men undergoing biliopancreatic derivation surgery and 11 lean to obese men undergoing general abdominal surgery. AKR1C2 mRNA and 5alpha-DHT inactivation were detected in both s.c. and Om adipose tissue. After incubation of preadipocytes with 5alpha-DHT, both 3alpha-diol and 3beta-diol were produced through 3alpha/beta-ketosteroid reductase (3alpha/beta-HSD) activity. In preadipocyte cultures, 3alpha-reductase activity was significantly predominant over 3beta-reductase activity in cells from both the s.c. and Om compartments. Expression levels of AKR1C1, AKR1C3 and of the androgen receptor were significantly higher in s.c. versus Om adipose tissue while mRNA levels of 17beta-HSD-2 (hydroxysteroid dehydrogenase type 2) and 3(alpha-->beta)-hydroxysteroid epimerase were significantly higher in Om fat. 3Alpha/beta-HSD activity was mainly detected in the cytosolic fraction, suggesting that AKR1C may be responsible for this reaction. Experiments with isoform-specific AKR1C inhibitors in preadipocytes showed that AKR1C2 inhibition significantly decreased 3alpha-HSD and 3beta-HSD activities (3alpha-HSD: 30 +/- 24% of control for s.c. and 32 +/- 9% of control for Om, 3beta-HSD: 44 +/- 12% of control for s.c.). When cells were incubated with both AKR1C2 and AKR1C3 inhibitors, no significant additional inhibition was observed. 5Alpha-DHT inactivation was significantly higher in mature adipocytes compared with preadipocyte cultures in s.c. adipose tissue, as expressed per microgram total protein (755 +/- 830 versus 245 +/- 151 fmol 3alpha/beta-diol per microg protein over 24 h, P < 0.05 n = 10 cultures). 5Alpha-DHT inactivation measured in tissue homogenates was significantly higher in the s.c. depot compared with Om fat (117 +/- 39 versus 79 +/- 38 fmol 3alpha/beta-diol per microg prot over 24 h, P < 0.0001). On the other hand, Om 3alpha/beta-HSD activity was significantly higher in obese men (body mass index (BMI) >or= 30 kg/m2) compared with lean and overweight men (84 +/- 37 versus 52 +/- 30 fmol 3alpha/beta-diol per microg protein over 24 h, P < 0.03). No difference was found in s.c. 3alpha/beta-HSD activity between these groups. Positive correlations were found between s.c. 5alpha-DHT inactivation rate and circulating levels of the androgen metabolites androsterone-glucuronide (r = 0.41, P < 0.02) and 3alpha-diol-glucuronide (r = 0.38, P < 0.03) and with the adrenal precursor androstenedione (r = 0.42, P < 0.02). In conclusion, androgen inactivation was detected in abdominal adipose tissue in men, with higher 3alpha/beta-HSD activity in the s.c. versus Om depot. Higher Om 5alpha-DHT inactivation rates were found in obese compared with lean men. Further studies are required to elucidate whether local androgen inactivation in abdominal adipose tissue is involved in the modulation of adipocyte metabolism and regional fat distribution in men.
 ...
PMID:Androgen inactivation and steroid-converting enzyme expression in abdominal adipose tissue in men. 1717 Feb 21

The skin is a well-recognized site of steroid formation and metabolism. Episkin is a cultured human epidermis. In this report, we investigate whether Episkin possesses a steroidogenic machinery able to metabolize adrenal steroid precursors into active steroids. Episkin was incubated with [14C]-dehydroepiandrosterone (DHEA) and 4-androstenedione (4-dione) and their metabolites were analyzed by liquid chromatography/mass spectrometry (LC/MS/MS). The results show that the major product of DHEA metabolism in Episkin is DHEA sulfate (DHEAS) (88% of the metabolites) while the other metabolites are 7alpha-OH-DHEA (8.2%), 4-dione (1.3%), 5-androstenediol (1.3%), dihydrotestosterone (DHT) (1.4%) and androsterone (ADT) (2.3%). When 4-dione is used as substrate, much higher levels of C19-steroids are produced with ADT representing 77% of the metabolites. These data indicate that 5alpha-reductase, 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and 3alpha-hydroxysteroid dehdyrogenase (3alpha-HSD) activities are present at moderate levels in Episkin, while 3beta-HSD activity is low and represents a rate-limiting step in the conversion of DHEA into C19-steroids. Using realtime PCR, we have measured the level of mRNAs encoding the steroidogenic enzymes in Episkin. A good agreement is found between the mRNAs expression in Episkin and the metabolic profile. High expression levels of steroid sulfotransferase SULT2B1B and type 3 3alpha-HSD (AKR1C2) correspond to the high levels of DHEA sulfate (DHEAS) and ADT formed from DHEA and 4-dione, respectively. 3beta-HSD is almost undetectable while the other enzymes such as type 1 5alpha-reductase, types 2, 4, 5, 7, 8, and 10 17beta-HSD and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) (AKR1C1) are highly expressed. Except for UGT-glucuronosyl transferase, similar mRNA expression profiles between Episkin and human epidermis are observed.
 ...
PMID:Steroid metabolism and profile of steroidogenic gene expression in Episkin: high similarity with human epidermis. 1766 97

Aldo-keto reductase (AKR) 1C3 (type 2 3alpha-HSD, type 5 17beta-HSD, and prostaglandin F synthase) regulates ligand access to steroid hormone and prostaglandin receptors and may stimulate proliferation of prostate and breast cancer cells. NSAIDs are known inhibitors of AKR1C enzymes. An NSAID analogue that inhibits AKR1C3 but is inactive against the cyclooxygenases and the other AKR1C family members would provide an important tool to examine the role of AKR1C3 in proliferative signaling. We tested NSAIDs and NSAID analogues for inhibition of the reduction of 9,10-phenanthrenequinone (PQ) catalyzed by AKR1C3 and the closely related isoforms AKR1C1 and AKR1C2. Two of the compounds initially screened, indomethacin and its methyl ester, were specific for AKR1C3 versus the other AKR1C isoforms. Based on these results and the crystal structure of AKR1C3, we predicted that N-(4-chlorobenzoyl)-melatonin (CBM), an indomethacin analogue that does not inhibit the cyclooxygenases, would selectively inhibit AKR1C3. CBM inhibited the reduction of PQ by AKR1C3, but did not significantly inhibit AKR1C1 or AKR1C2. Indomethacin and CBM also inhibited the AKR1C3-catalyzed reduction of Delta(4)-androstene-3,17-dione but did not significantly inhibit the reduction of steroid hormones catalyzed by AKR1C1 or AKR1C2. The pattern of inhibition of AKR1C3 by indomethacin and CBM was uncompetitive versus PQ, but competitive versus Delta(4)-androstene-3,17-dione, indicating that two different inhibitory complexes form during the ordered bi bi reactions. The identification of CBM as a specific inhibitor of AKR1C3 will aid the investigation of its roles in steroid hormone and prostaglandin signaling and the resultant effects on cancer development.
 ...
PMID:An indomethacin analogue, N-(4-chlorobenzoyl)-melatonin, is a selective inhibitor of aldo-keto reductase 1C3 (type 2 3alpha-HSD, type 5 17beta-HSD, and prostaglandin F synthase), a potential target for the treatment of hormone dependent and hormone independent malignancies. 1795 Feb 53

20alpha-hydroxysteroid dehydrogenase (AKR1C1) plays a key role in the metabolism of progesterone and other steroid hormones, thereby regulating their action at the pre-receptor level. AKR1C1 is implicated in neurological and psychiatric conditions such as catamenial epilepsy and depressive disorders. Increased activity of AKR1C1 is associated with termination of pregnancy and the development of breast cancer, endometriosis and endometrial cancer. Inhibition of the undesired activity of AKR1C1 will help reduce risks of premature birth, neurological disorders and the development of cancer. In order to identify potential leads for new inhibitors of AKR1C1 we adopted a virtual screening-based approach using the automated DOCK program. Approximately 250,000 compounds from the NCI database were screened for potential ligands based on their chemical complementarity and steric fit within the active site of AKR1C1. Kinetic analysis revealed 3,5-diiodosalicylic acid, an analogue of salicylic acid, as a potent competitive inhibitor with respect to the substrate 5beta-pregnane-3alpha,20alpha-diol with a K(i) of 9 nM. Aspirin, which is a well known salicylic acid-based drug, was also found to inhibit AKR1C1 activity. This is the first report to show aspirin (IC(50)=21 microM) and its metabolite salicylic acid (IC(50)=7.8 microM) as inhibitors of AKR1C1.
 ...
PMID:A salicylic acid-based analogue discovered from virtual screening as a potent inhibitor of human 20alpha-hydroxysteroid dehydrogenase. 1804 4

The crystal structure of human 20alpha-hydroxysteroid dehydrogenase (AKR1C1) in ternary complex with the coenzyme NADP (+) and the potent inhibitor 3,5-dichlorosalicylic acid was determined at a resolution of 1.8 A. The inhibitor is held in place by a network of hydrogen bonding interactions with the active site residues Tyr55, His117, and His222. The important role of the nonconserved residues Leu54, His222, Leu306, and Leu308 in inhibitor binding and selectivity was determined by site-directed mutagenesis.
 ...
PMID:Selectivity determinants of inhibitor binding to human 20alpha-hydroxysteroid dehydrogenase: crystal structure of the enzyme in ternary complex with coenzyme and the potent inhibitor 3,5-dichlorosalicylic acid. 1862 Mar 80


1 2 Next >>