title: The effects of the standardized extracts of Ginkgo biloba on steroidogenesis pathways and aromatase activity in H295R human adrenocortical carcinoma cells.
abstract: OBJECTIVE
  Aromatase inhibitors that block estrogen synthesis are a proven first-line hormonal therapy for postmenopausal breast cancer. Although it is known that standardized extract of Ginkgo biloba (EGb761) induces anti-carcinogenic effects like the aromatase inhibitors, the effects of EGb761 on steroidogenesis have not been studied yet. Therefore, the effects of EGb761 on steroidogenesis and aromatase activity was studied using a H295R cell model, which was a good in vitro model to predict effects on human adrenal steroidogenesis.
  
  
  METHODS
  Cortisol, aldosterone, testosterone, and 17β-estradiol were evaluated in the H295R cells by competitive enzyme-linked immunospecific assay after exposure to EGb761. Real-time polymerase chain reaction were performed to evaluate effects on critical genes in steroid hormone production, specifically cytochrome P450 (CYP11/ 17/19/21) and the hydroxysteroid dehydrogenases (3β-HSD2 and 17β-HSD1/4). Finally, aromatase activities were measured with a tritiated water-release assay and by western blotting analysis.
  
  
  RESULTS
  H295R cells exposed to EGb761 (10 and 100 μg/mL) showed a significant decrease in 17β-estradiol and testosterone, but no change in aldosterone or cortisol. Genes (CYP19 and 17β-HSD1) related to the estrogen steroidogenesis were significantly decreased by EGb761. EGb761 treatment of H295R cells resulted in a significant decrease of aromatase activity as measured by the direct and indirect assays. The coding sequence/ Exon PII of CYP19 gene transcript and protein level of CYP19 were significantly decreased by EGb761.
  
  
  CONCLUSIONS
  These results suggest that EGb761 could regulate steroidogenesis-related genes such as CYP19 and 17β-HSD1, and lead to a decrease in 17β-estradiol and testosterone. The present study provides good information on potential therapeutic effects of EGb761 on estrogen dependent breast cancer.
authors.affiliation: Oncology and Antimicrobial Products Division, National Institute of Food and Drug Safety Evaluation, Cheongju, Korea.
authors.forename: Mijie
authors.identifier: 0000-0002-4715-7641
authors.initials: M
authors.lastname: Kim
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon, Korea.
authors.forename: Yong Joo
authors.identifier: 0000-0002-0528-6197
authors.initials: YJ
authors.lastname: Park
authors.affiliation: Department of Nanofusion Technology, Hoseo University, Asan, Korea.
authors.forename: Huiyeon
authors.identifier: 0000-0001-5030-1600
authors.initials: H
authors.lastname: Ahn
authors.affiliation: Department of Nanofusion Technology, Hoseo University, Asan, Korea.
authors.forename: Byeonghak
authors.identifier: 0000-0002-2018-6418
authors.initials: B
authors.lastname: Moon
authors.affiliation: School of Pharmacy, Sungkyunkwan University, Suwon, Korea.
authors.forename: Kyu Hyuck
authors.identifier: 0000-0003-4283-0742
authors.initials: KH
authors.lastname: Chung
authors.affiliation: Department of Nanofusion Technology, Hoseo University, Asan, Korea.
authors.forename: Seung Min
authors.identifier: 0000-0002-5701-8960
authors.initials: SM
authors.lastname: Oh
keywords: Aromatase inhibitor; Ginkgo biloba extracts; H295R cells; Steroidogenesis