Genistein Inhibits Proliferation of BRCA1 Mutated Breast Cancer Cells: The GPR30-Akt Axis as a Potential Target
Ga Yun Kim1,2, Jinyoung Suh2, Jeong-Hoon Jang2
1Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea.
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 G2/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.
Insights
Genistein, a soy isoflavone, inhibits proliferation in BRCA1-mutant breast cancer by downregulating GPR30 and Akt signaling. This leads to cell cycle arrest and reduced ROS, offering a potential therapeutic strategy for triple-negative breast cancer.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- BRCA1 mutations are linked to aggressive breast cancer with higher proliferation and metastatic potential.
- Estrogen receptor-negative breast cancer, often associated with BRCA1 mutations, shows high expression of G protein-coupled receptor 30 (GPR30).
- Genistein, a soy-derived isoflavone, possesses chemopreventive properties investigated for its effects on cancer cells.
Purpose of the Study:
- To investigate the antiproliferative effects of genistein in triple-negative breast cancer cells with or without functional BRCA1.
- To elucidate the molecular mechanisms underlying genistein's action, focusing on GPR30 and Akt signaling pathways.
- To assess the role of reactive oxygen species (ROS) and Nrf2 in BRCA1-mutant breast cancer response to genistein.
Main Methods:
- Western blot analysis was used to measure the expression of BRCA1, GPR30, and Nrf2.
- Reactive oxygen species (ROS) levels were monitored using a fluorescence-based assay.
- Cell viability, proliferation, migration, and colony formation were assessed using MTT, migration, and clonogenic assays, respectively.
Main Results:
- BRCA1-mutant breast cancer cells exhibited significantly higher GPR30 expression compared to wild-type cells.
- Genistein treatment downregulated GPR30, inhibited Akt phosphorylation, and reduced cell viability, migration, and colony formation in BRCA1-silenced cells.
- Genistein induced G2/M phase cell cycle arrest by downregulating cyclin B1 and lowered ROS levels via Nrf2 upregulation in BRCA1-mutant cells.
Conclusions:
- Loss of BRCA1 function activates GPR30 signaling, promoting Akt phosphorylation and cell proliferation in breast cancer.
- Genistein effectively suppresses GPR30 activation and Akt phosphorylation in BRCA1-impaired breast cancer cells, leading to cell cycle arrest.
- Genistein's ability to reduce ROS through Nrf2 upregulation presents a promising therapeutic avenue for BRCA1-mutant triple-negative breast cancer.
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