title: Important roles of the AKR1C2 and SRD5A1 enzymes in progesterone metabolism in endometrial cancer model cell lines.
abstract: Endometrial cancer is the most frequently diagnosed gynecological malignancy. It is associated with prolonged exposure to estrogens that is unopposed by progesterone, whereby enhanced metabolism of progesterone may decrease its protective effects, as it can deprive progesterone receptors of their active ligand. Furthermore, the 5α-pregnane metabolites formed can stimulate proliferation and may thus contribute to carcinogenesis. The aims of our study were to: (1) identify and quantify progesterone metabolites formed in the HEC-1A and Ishikawa model cell lines of endometrial cancer; and (2) pinpoint the enzymes involved in progesterone metabolism, and delineate their roles. Progesterone metabolism studies combined with liquid chromatography-tandem mass spectrometry enabled identification and quantification of the metabolites formed in these cells. Further quantitative PCR analysis and small-interfering-RNA-mediated gene silencing identified individual progesterone metabolizing enzymes and their relevant roles. In Ishikawa and HEC-1A cells, progesterone was metabolized mainly to 20α-hydroxy-pregn-4-ene-3-one, 20α-hydroxy-5α-pregnane-3-one, and 5α-pregnane-3α/β,20α-diol. The major difference between these cell lines was rate of progesterone metabolism, which was faster in HEC-1A cells. In the Ishikawa and HEC-1A cells, expression of AKR1C2 was 110-fold and 6800-fold greater, respectively, than expression of AKR1C1, which suggests that 20-ketosteroid reduction of 5α-pregnanes and 4-pregnenes is catalyzed mainly by AKR1C2. AKR1C1/AKR1C2 gene silencing showed decreased progesterone metabolism in both cell lines, thus further supporting the significant role of AKR1C2. SRD5A1 was also expressed in these cells, and its silencing confirmed that 5α-reduction is catalyzed by 5α-reductase type 1. Silencing of SRD5A1 also had the most pronounced effects, with decreased rate of progesterone metabolism, and consequently higher concentrations of unmetabolized progesterone. Our data confirm that in model cell lines of endometrial cancer, AKR1C2 and SRD5A1 have crucial roles in progesterone metabolism, and may represent novel targets for treatment.
authors.affiliation: Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Maša
authors.initials: M
authors.lastname: Sinreih
authors.affiliation: Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Anko
authors.affiliation: Institute of Experimental Genetics, Genome Analysis Centre, Helmholtz Zentrum München, München, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Zukunft
authors.affiliation: Institute of Experimental Genetics, Genome Analysis Centre, Helmholtz Zentrum München, München, Germany; Lehrstuhl für Experimentelle Genetik, Technische Universität München, 85356 Freising-Weihenstephan, Germany; German Centre for Diabetes Research, 85764 Neuherberg, Germany.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Adamski
authors.affiliation: Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia. Electronic address: Tea.Lanisnik-Rizner@mf.uni-lj.si.
authors.forename: Tea Lanišnik
authors.initials: TL
authors.lastname: Rižner
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism*; D045744:Cell Line, Tumor; D016889:Endometrial Neoplasms / Q000378:metabolism*; D005260:Female; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007664:Ketosteroids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D011278:Pregnanes / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism*; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific)
chemical_list: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase; D006913:Hydroxysteroid Dehydrogenases; D007664:Ketosteroids; D008565:Membrane Proteins; D011278:Pregnanes; D011374:Progesterone; C435496:AKR1C2 protein, human; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); C548467:SRD5A1 protein, human
keywords: 3-Keto/20-keto-reductases; 4-Pregnenes; 5α-Pregnanes; 5α-Reductases; Pre-receptor metabolism