The Inhibitory Effects of the Standardized Extracts of Ginkgo biloba on Aromatase Activity in JEG-3 Human Choriocarcinoma Cells

Authors

  • Mi Jie Kim,

    1. School of Pharmacy, Sungkyunkwan University, Jangan-gu, Suwon, Kyeonggi-do, South Korea
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  • Yong Joo Park,

    1. School of Pharmacy, Sungkyunkwan University, Jangan-gu, Suwon, Kyeonggi-do, South Korea
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  • Kyu Hyuck Chung,

    Corresponding author
    1. School of Pharmacy, Sungkyunkwan University, Jangan-gu, Suwon, Kyeonggi-do, South Korea
    • Correspondence to: Kyu Hyuck Chung, School of Pharmacy, Sungkyunkwan University, 300 Cheoncheon dong, Jangan-gu, Suwon, Kyeonggi-do 440-746, South Korea; Seung Min Oh, Hoseo Fusion Technology Laboratory, Hoseo University, 165 Sechul-ri, Asan, ChungcheongNam-do, 336-795, South Korea.

      E-mail: khchung@skku.edu; ohsm0403@hoseo.edu

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    • S.M. Oh and K.H. Chung contributed equally
  • Seung Min Oh

    Corresponding author
    1. Hoseo Fusion Technology Laboratory, Hoseo University, ChungcheongNam-do, South Korea
    • Correspondence to: Kyu Hyuck Chung, School of Pharmacy, Sungkyunkwan University, 300 Cheoncheon dong, Jangan-gu, Suwon, Kyeonggi-do 440-746, South Korea; Seung Min Oh, Hoseo Fusion Technology Laboratory, Hoseo University, 165 Sechul-ri, Asan, ChungcheongNam-do, 336-795, South Korea.

      E-mail: khchung@skku.edu; ohsm0403@hoseo.edu

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    • S.M. Oh and K.H. Chung contributed equally

Abstract

Breast cancer is the most common cancer in women worldwide. There are many endocrine adjuvant therapies for breast cancer patients that are categorized according to their mechanisms. Among them, aromatase inhibitors (AIs) that block the synthesis of estrogens have proven superiority compared with tamoxifen and have replaced it as a first-line hormonal therapy. However, AIs also have limitations due to their side effects – increased rate of bone loss and musculoskeletal complaints. We therefore need new candidate AIs with fewer side effects. The extracts of Ginkgo biloba (EGb), which contain phytochemicals from the tree, had biphasic effects for estrogens and osteoporosis-inhibiting activities in our previous experiments. In this study, we explored the possibility of EGb as an AI and their mechanisms. Aromatase activities were inhibited by EGb both in JEG-3 cells and in recombinant CYP19 microsomes. The results of polymerase chain reaction for aromatase from a coding sequence and specific promoter sequences (exon I.a, exon I.c) in JEG-3 cells as well as the results of reporter gene assays showed that EGb dose-dependently decreased the aromatase gene expression. The decreased protein levels were demonstrated by Western blotting. From these results, we concluded that EGb could act as an AI at both the enzyme and transcriptional levels. Copyright © 2013 John Wiley & Sons, Ltd.

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