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Publication Abstract from PubMed

Human 3alpha-HSD3 (3alpha-hydroxysteroid dehydrogenase type 3) plays an essential role in the inactivation of the most potent androgen 5alpha-DHT (5alpha-dihydrotestosterone). The present study attempts to obtain the important structure of 3alpha-HSD3 in complex with 5alpha-DHT and to investigate the role of 3alpha-HSD3 in breast cancer cells. We report the crystal structure of human 3alpha-HSD3.NADP(+).A-dione (5alpha-androstane-3,17-dione)/epi-ADT (epiandrosterone) complex, which was obtained by co-crystallization with 5alpha-DHT in the presence of NADP(+) Although 5alpha-DHT was introduced during the crystallization, oxidoreduction of 5alpha-DHT occurred. The locations of A-dione and epi-ADT were identified in the steroid-binding sites of two 3alpha-HSD3 molecules per crystal asymmetric unit. An overlay showed that A-dione and epi-ADT were oriented upside-down and flipped relative to each other, providing structural clues for 5alpha-DHT reverse binding in the enzyme with the generation of different products. Moreover, we report the crystal structure of the 3alpha-HSD3.NADP(+).4-dione (4-androstene-3,17-dione) complex. When a specific siRNA (100 nM) was used to suppress 3alpha-HSD3 expression without interfering with 3alpha-HSD4, which shares a highly homologous active site, the 5alpha-DHT concentration increased, whereas MCF7 cell growth was suppressed. The present study provides structural clues for 5alpha-DHT reverse binding within 3alpha-HSD3, and demonstrates for the first time that down-regulation of 3alpha-HSD3 decreases MCF7 breast cancer cell growth.

Human 3alpha-hydroxysteroid dehydrogenase type 3: structural clues of 5alpha-DHT reverse binding and enzyme down-regulation decreasing MCF7 cell growth.,Zhang B, Hu XJ, Wang XQ, Theriault JF, Zhu DW, Shang P, Labrie F, Lin SX Biochem J. 2016 Apr 15;473(8):1037-46. doi: 10.1042/BCJ20160083. Epub 2016 Feb, 29. PMID:26929402^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.