title: Role of AMP-activated protein kinase on steroid hormone biosynthesis in adrenal NCI-H295R cells.
abstract: Regulation of human androgen biosynthesis is poorly understood. However, detailed knowledge is needed to eventually solve disorders with androgen dysbalance. We showed that starvation growth conditions shift steroidogenesis of human adrenal NCI-H295R cells towards androgen production attributable to decreased HSD3B2 expression and activity and increased CYP17A1 phosphorylation and 17,20-lyase activity. Generally, starvation induces stress and energy deprivation that need to be counteracted to maintain proper cell functions. AMP-activated protein kinase (AMPK) is a master energy sensor that regulates cellular energy balance. AMPK regulates steroidogenesis in the gonad. Therefore, we investigated whether AMPK is also a regulator of adrenal steroidogenesis. We hypothesized that starvation uses AMPK signaling to enhance androgen production in NCI-H295R cells. We found that AMPK subunits are expressed in NCI-H295 cells, normal adrenal tissue and human as well as pig ovary cells. Starvation growth conditions decreased phosphorylation, but not activity of AMPK in NCI-H295 cells. In contrast, the AMPK activator 5-aminoimidazole-4-carboxamide (AICAR) increased AMPKα phosphorylation and increased CYP17A1-17,20 lyase activity. Compound C (an AMPK inhibitor), directly inhibited CYP17A1 activities and can therefore not be used for AMPK signaling studies in steroidogenesis. HSD3B2 activity was neither altered by AICAR nor compound C. Starvation did not affect mitochondrial respiratory chain function in NCI-H295R cells suggesting that there is no indirect energy effect on AMPK through this avenue. In summary, starvation-mediated increase of androgen production in NCI-H295 cells does not seem to be mediated by AMPK signaling. But AMPK activation can enhance androgen production through a specific increase in CYP17A1-17,20 lyase activity.
authors.affiliation: Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, Inselspital, University Hospital, University of Bern, Bern, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hirsch
authors.forename: Dagmar
authors.initials: D
authors.lastname: Hahn
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: Jean-Marc
authors.initials: JM
authors.lastname: Nuoffer
authors.forename: Christa E
authors.initials: CE
authors.lastname: Flück
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000311:Adrenal Glands / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000728:Androgens / Q000096:biosynthesis*; D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D016895:Culture Media, Serum-Free; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis*; D013552:Swine
chemical_list: D000728:Androgens; D016895:Culture Media, Serum-Free; D007093:Imidazoles; D021122:Protein Subunits; D011720:Pyrazoles; D011743:Pyrimidines; D034741:RNA, Small Interfering; D013256:Steroids; C516138:dorsomorphin; C029899:imidazole; D013254:Steroid 17-alpha-Hydroxylase; D055372:AMP-Activated Protein Kinases