Hiroyoshi Doihara
   Department   Kawasaki Medical School  Kawasaki Medical School, Department of General Surgery,
   Position   Professor with Special Assignment
Article types 原著
Language English
Peer review Peer reviewed
Title Effect of isoflavones on breast cancer cell development and their impact on breast cancer treatments.
Journal Formal name:Breast cancer research and treatment
Abbreviation:Breast Cancer Res Treat
ISSN code:15737217/01676806
Domestic / ForeginForegin
Volume, Issue, Page 185(2),pp.307-316
Author and coauthor Hatono Minami, Ikeda Hirokuni, Suzuki Yoko, Kajiwara Yukiko, Kawada Kengo, Tsukioki Takahiro, Kochi Mariko, Suzawa Ken, Iwamoto Takayuki, Yamamoto Hiromasa, Shien Tadahiko, Yamane Masaomi, Taira Naruto, Doihara Hiroyoshi, Toyooka Shinichi
Publication date 2021/01
Summary PURPOSE:Epidemiological studies have suggested that intake of soy isoflavones is associated with a reduced risk of development of breast cancer and an improved prognosis in patients with breast cancer. In addition, basic research has demonstrated the antitumor effects of these compounds on breast cancer cell lines. However, the detailed effects of the intake of equol, which is one of the metabolites of the soy isoflavones, are yet to be clarified on the risk of development and recurrence of breast cancer and its interactions with drugs used for treating breast cancer. This study aimed to determine the antitumor effects of equol and investigate the impact of adding equol to therapeutic agents for breast cancer using breast cancer cell lines.METHODS:We examined the antitumor effect of equol on breast cancer cell lines using MTS assay. We also studied the combined effect of equol and the existing hormonal or chemotherapeutic agents using combination index. We evaluated the expressions of the related proteins by Western blot analysis and correlated the findings with the antitumor effect.RESULTS:Equol showed bi-phasic protumor and antitumor effects; at a low concentration, it promoted the tumor growth in hormone receptor-positive cell lines, whereas antitumor effects were generally observed when an excessive amount of dose unexpected in the blood and the tissue was administered. When used with tamoxifen, equol might have some antagonistic effect, although it depends on equol concentration and the type of cancer cells.CONCLUSIONS:We confirmed that equol has dual action, specifically a tumor growth-promoting effect and an antitumor effect. Although the results suggested that equol might exert an antagonistic effect against tamoxifen depending on the concentration, equol did not exert an antagonistic effect on other therapeutic agents.
DOI 10.1007/s10549-020-05957-z
PMID 33034801