Environ Health Toxicol.  2016 ;31(1):e2016010. 10.5620/eht.e2016010.

The effects of the standardized extracts of Ginkgo biloba on steroidogenesis pathways and aromatase activity in H295R human adrenocortical carcinoma cells

• Kim M
• Park YJ
• Ahn H
• Moon B
• Chung KH
• Oh SM

• KMID: 2469666
• DOI: http://doi.org/10.5620/eht.e2016010

Abstract

OBJECTIVES
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.

Keyword

Ginkgo biloba extracts; Aromatase inhibitor; H295R cells; Steroidogenesis

MeSH Terms

Adrenocortical Carcinoma*
Aldosterone
Anticarcinogenic Agents
Aromatase Inhibitors
Aromatase*
Blotting, Western
Breast Neoplasms
Clinical Coding
Cytochrome P-450 Enzyme System
Estrogens
Exons
Ginkgo biloba*
Humans*
Hydrocortisone
Hydroxysteroid Dehydrogenases
In Vitro Techniques
Real-Time Polymerase Chain Reaction
Testosterone
Therapeutic Uses
Aldosterone
Anticarcinogenic Agents
Aromatase
Aromatase Inhibitors
Cytochrome P-450 Enzyme System
Estrogens
Hydrocortisone
Hydroxysteroid Dehydrogenases
Testosterone
Therapeutic Uses