title: Limited in vitro efficacy of CYP17A1 inhibition on human castration resistant prostate cancer.
abstract: Although accumulating evidence indicates high expression of CYP17A1(P45017A1) allows castration resistant prostate cancer (CRPC) to maintain high intratumoral androgen levels, the potential P45017A1 activity has not been characterized yet. The aim of this study was to examine the potential CYP17A1 activity including 17α-hydroxylase and 17,20-lyase activities in human CRPC and the effect of a CYP17A inhibitor. We used three human CRPC cell lines: C4-2 and C4-2AT6 which was established from C4-2 under androgen ablation conditions for 6months, and PC3. To ascertain the potential CYP17A1 activity, we cultured with the steroid precursors: (13)C-[2,3,4]-progesterone (13C-Prog), and analyzed the sequential biosynthesis (13)C-[2,3,4]-17-hydroxyprogesterone (13C-17OHP) and (13)C-[2,3,4]-androstenedione(13C-Adione) by liquid chromatography/mass spectrometry (LC/MS/MS).The C4-2AT6 cells showed significantly higher CYP17A1 expression than C4-2 cells (p<0.001). LC/MS/MS analysis enabled us to detect the 13C-17-OHP and 13C-A-dione in these cell lines. The concentration ratio of 13C-Adione/13C-17OHP (Adione-17OHP ratio), which is thought to reflect the differences between 17-hydroxylase and 17,20-lyase activities, was then determined. The Adione-17OHP ratio in C4-2AT6 cells was significantly higher than that of C4-2 cells (p<0.001). Abiraterone were able to inhibit the CYP17A activities, although abiraterone did not have anti-proliferative effects on C4-2 and C4-2AT6 cells at clinically achievable concentrations of <1000nM in vitro. The present study clearly demonstrates CRPC have the dual activities of CYP17A1 mediated by 17-hydroxylase activity and 17,20-lyase activity. Abiraterone doesn't have an in vitro anti-proliferative efficacy in CRPC cells, suggesting limited efficacy in vitro.
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: takemduro@gmail.com.
authors.forename: Takeo
authors.initials: T
authors.lastname: Kosaka
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: akiram@a8.keio.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Miyajima
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Yota
authors.initials: Y
authors.lastname: Yasumizu
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Miyazaki
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Kikuchi
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Oya
mesh_terms: D000736:Androstenes / Q000494:pharmacology; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008297:Male; D064129:Prostatic Neoplasms, Castration-Resistant / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D000736:Androstenes; C501892:CYP17A1 protein, human; D013254:Steroid 17-alpha-Hydroxylase; C089740:abiraterone
keywords: Abiraterone; C4-2AT6; CYP17A1; Castration-resistant prostate cancer; Liquid chromatography/mass spectrometry; P45017A1