Hydroxysteroid dehydrogenases AKR1C1–AKR1C3, members of the aldo-keto reductase superfamily, are involved in metabolism of steroid hormones, neurosteroids, xenobiotics and prostaglandins. AKR1C3 catalyzes reduction of androstenedione to testosterone and estrone to estradiol, and may thus promote the excessive proliferation of prostate and breast cells. AKR1C3 also catalyzes reduction of PGH2 to PGF2α and PGD2 to 9α,11β-PGF2 and thus prevents activation of PPARγ and cell apoptosis. AKR1C1 as 20-ketosteroid reductase inactivates progesterone by producing 20α-hydroxyprogesterone and also converts a potent neurosteroid 5α-pregnane-3α-ol-20-one to 5α-pregnane-3α,20α-diol. In this manner AKR1C1 prevents protective effects of progesterone in uterus and ectopic endometrium and is involved in promotion of endometrial cancer, endometriosis and premenstrual syndrome. Due to its role in neurosteroid metabolism it is also associated with depressive disorders. AKR1C2 catalyzes inactivation of 5α-DHT to 3α-androstanediol and thus protects prostate cells from excessive proliferation. AKR1C1 and AKR1C3 have important roles in different pathophysiological conditions so they represent important drug targets in hormone-dependent and hormone-independent cancers and other diseases. Previous studies showed that cinnamic acid derivatives and NSAID analogs inhibit AKR1C isoenzymes. Therefore, the aim of this study was to evaluate 56 compounds with similar structural characteristics from three different groups of compounds: 1) derivatives of fumaric acid, 2) derivatives of 3-aminobenzoic acid and 3) derivatives of 2-phenylcinnamic acid for their inhibition of the recombinant AKR1C1, AKR1C2 and AKR1C3 enzymes. First, we determined the percentages of inhibition of 1-acenaphthenol oxidation in the presence of 100 μM of individual compound and 30 μM, 60 μM and 100 μM concentration of substrate, respectively. The best inhibitors were derivatives of 2-phenylcinnamic acid. For compounds that showed at least 50 % inhibition of AKR1C1-AKR1C3 the IC50 values were determined. 17 compounds showed low μM IC50 values. The best inhibitor of AKR1C1 and AKR1C3 were compounds 13c and 26c with 6.6 μM and 5.8 μM IC50 values, respectively. We found 7 AKR1C3-specific inhibitors, compounds 26c, 21c, 24c, 10c, 22c, 23c and 1c, showing 5.8 μM; 10.8 μM; 16.8 μM; 38,7 μM; 43.1 μM; 69.8 μM and 121.1 μM IC50 values. These compounds represent good starting points for development of new AKR1C3-specific agents for treatment of acute myeloid leukemia and prostate and breast cancer.
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