title: Pioglitazone inhibits androgen production in NCI-H295R cells by regulating gene expression of CYP17 and HSD3B2.
abstract: Thiazolidinediones (TZDs) such as pioglitazone and rosiglitazone are widely used as insulin sensitizers in the treatment of type 2 diabetes. In diabetic women with polycystic ovary syndrome, treatment with pioglitazone or rosiglitazone improves insulin resistance and hyperandrogenism, but the mechanism by which TZDs down-regulate androgen production is unknown. Androgens are synthesized in the human gonads as well as the adrenals. We studied the regulation of androgen production by analyzing the effect of pioglitazone and rosiglitazone on steroidogenesis in human adrenal NCI-H295R cells, an established in vitro model of steroidogenesis of the human adrenal cortex. Both TZDs changed the steroid profile of the NCI-H295R cells and inhibited the activities of P450c17 and 3betaHSDII, key enzymes of androgen biosynthesis. Pioglitazone but not rosiglitazone inhibited the expression of the CYP17 and HSD3B2 genes. Likewise, pioglitazone repressed basal and 8-bromo-cAMP-stimulated activities of CYP17 and HSD3B2 promoter reporters in NCI-H295R cells. However, pioglitazone did not change the activity of a cAMP-responsive luciferase reporter, indicating that it does not influence cAMP/protein kinase A/cAMP response element-binding protein pathway signaling. Although peroxisome proliferator-activated receptor gamma (PPARgamma) is the nuclear receptor for TZDs, suppression of PPARgamma by small interfering RNA technique did not alter the inhibitory effect of pioglitazone on CYP17 and HSD3B2 expression, suggesting that the action of pioglitazone is independent of PPARgamma. On the other hand, treatment of NCI-H295R cells with mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibitor 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059) enhanced promoter activity and expression of CYP17. This effect was reversed by pioglitazone treatment, indicating that the MEK/ERK signaling pathway plays a role in regulating androgen biosynthesis by pioglitazone.
authors.affiliation: Division of Pediatric Endocrinology and Diabetology, University Children's Hospital Bern, G3 812, Freiburgstrasse 15, 3010 Bern, Switzerland.
authors.forename: Petra
authors.initials: P
authors.lastname: Kempná
authors.forename: Gaby
authors.initials: G
authors.lastname: Hofer
authors.forename: Primus E
authors.initials: PE
authors.lastname: Mullis
authors.forename: Christa E
authors.initials: CE
authors.lastname: Flück
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000235:genetics*; D000311:Adrenal Glands / Q000378:metabolism*; D000728:Androgens / Q000096:biosynthesis*; D001483:Base Sequence; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008969:Molecular Sequence Data; D047495:PPAR gamma / Q000502:physiology; D000077205:Pioglitazone; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D000077154:Rosiglitazone; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics*; D045162:Thiazolidinediones / Q000494:pharmacology*
chemical_list: D000728:Androgens; D017362:Cyclic AMP Response Element-Binding Protein; D007004:Hypoglycemic Agents; D047495:PPAR gamma; D012333:RNA, Messenger; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D000242:Cyclic AMP; D015096:3-Hydroxysteroid Dehydrogenases; D013254:Steroid 17-alpha-Hydroxylase; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D000077205:Pioglitazone