title: Impaired dihydrotestosterone catabolism in human prostate cancer: critical role of AKR1C2 as a pre-receptor regulator of androgen receptor signaling.
abstract: We previously reported the selective loss of AKR1C2 and AKR1C1 in prostate cancers compared with their expression in paired benign tissues. We now report that dihydrotestosterone (DHT) levels are significantly greater in prostate cancer tumors compared with their paired benign tissues. Decreased catabolism seems to account for the increased DHT levels as expression of AKR1C2 and SRD5A2 was reduced in these tumors compared with their paired benign tissues. After 4 h of incubation with benign tissue samples, (3)H-DHT was predominantly catabolized to the 5alpha-androstane-3alpha,17beta-diol metabolite. Reduced capacity to metabolize DHT was observed in tumor samples from four of five freshly isolated pairs of tissue samples, which paralleled loss of AKR1C2 and AKR1C1 expression. LAPC-4 cells transiently transfected with AKR1C1 and AKR1C2, but not AKR1C3, were able to significantly inhibit a dose-dependent, DHT-stimulated proliferation, which was associated with a significant reduction in the concentration of DHT remaining in the media. R1881-stimulated proliferation was equivalent in all transfected cells, showing that metabolism of DHT was responsible for the inhibition of proliferation. PC-3 cells overexpressing AKR1C2 and, to a lesser extent, AKR1C1 were able to significantly inhibit DHT-dependent androgen receptor reporter activity, which was abrogated by increasing DHT levels. We speculate that selective loss of AKR1C2 in prostate cancer promotes clonal expansion of tumor cells by enhancement of androgen-dependent cellular proliferation by reducing DHT metabolism.
authors.affiliation: Department of Medicine, Keck School of Medicine, University of Southern California, 2011 Zonal Avenue, Los Angeles, CA 90033, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Ji
authors.forename: Lilly
authors.initials: L
authors.lastname: Chang
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: Murad
authors.initials: M
authors.lastname: Ookhtens
authors.forename: Andy
authors.initials: A
authors.lastname: Sherrod
authors.forename: Andrew
authors.initials: A
authors.lastname: Stolz
mesh_terms: D015089:20-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D000368:Aged; D059002:Androgen Receptor Antagonists; D013196:Dihydrotestosterone / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000378:metabolism*; D011944:Receptors, Androgen / Q000378:metabolism*; D015398:Signal Transduction; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)
chemical_list: D015089:20-Hydroxysteroid Dehydrogenases; D059002:Androgen Receptor Antagonists; D013196:Dihydrotestosterone; D006913:Hydroxysteroid Dehydrogenases; D011944:Receptors, Androgen; C115140:3 alpha-beta, 20 beta-hydroxysteroid dehydrogenase; C435496:AKR1C2 protein, human; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)