J Cancer Prev.  2019 Dec;24(4):197-207. 10.15430/JCP.2019.24.4.197.

Genistein Inhibits Proliferation of BRCA1 Mutated Breast Cancer Cells: The GPR30-Akt Axis as a Potential Target

• Kim GY
• Suh J
• Jang JH
• Kim DH
• Park OJ
• Park SK
• Surh YJ

• KMID: 2468809
• DOI: http://doi.org/10.15430/JCP.2019.24.4.197

Abstract

BACKGROUND
BRCA1 mutated breast cancer cells exhibit the elevated cell proliferation and the higher metastatic potential. G protein-coupled receptor 30 (GPR30) has been shown to regulate growth of hormonally responsive cancers, such as ovarian and breast cancers, and high expression of GPR30 is found in estrogen receptor (ER)-negative breast cancer cells. ER-negative breast cancer patients often have a mutation in the tumor suppressor gene, BRCA1. This study explored antiproliferative effects of genistein, a chemopreventive isoflavone present in legumes, and underlying molecular mechanisms in triple negative breast cancer cells with or without functionally active BRCA1.
METHODS
Expression of BRCA1, GPR30 and Nrf2 was measured by Western blot analysis. Reactive oxygen species (ROS) accumulation was monitored by using the fluorescence-generating probe, 2',7'-dichlorofluorescein diacetate. The effects of genistein on breast cancer cell viability and proliferation were assessed by the MTT, migration and clonogenic assays.
RESULTS
The expression of GPR30 was dramatically elevated at both transcriptional and translational levels in BRCA1 mutated breast cancer cells compared to cells with wild-type BRCA1. Notably, there was diminished Akt phosporylation in GPR30 silenced cells. Treatment of BRCA1 silenced breast cancer cells with genistein resulted in the down-regulation of GPR30 expression and the inhibition of Akt phosphorylation as well as the reduced cell viability, migration and colony formation. Genistein caused cell cycle arrest at the Gâ‚‚/M phase in BRCA1-mutant cells through down-regulation of cyclin B1 expression. Furthermore, BRCA1-mutant breast cancer cells exhibited higher levels of intracellular ROS than those in the wild-type cells. Genistein treatment lowered the ROS levels through up-regulation of Nrf2 expression.
CONCLUSIONS
Lack of functional BRCA1 activates GPR30 signaling, thereby stimulating Akt phosphorylation and cell proliferation. Genistein induces G2/M phase arrest by down-regulating cyclin B1 expression, which is attributable to its suppression of GPR30 activation and Akt phosphorylation in BRCA1 impaired breast cancer cells.

Keyword

BRCA1; GPR30; Genistein; Akt; Breast cancer

MeSH Terms

Blotting, Western
Breast Neoplasms*
Breast*
Cell Cycle Checkpoints
Cell Proliferation
Cell Survival
Cyclin B1
Down-Regulation
Estrogens
Fabaceae
Genes, Tumor Suppressor
Genistein*
Humans
Phosphorylation
Reactive Oxygen Species
Triple Negative Breast Neoplasms
Up-Regulation
Cyclin B1
Estrogens
Genistein
Reactive Oxygen Species