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

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 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.

Genistein: A Potent Anti-Breast Cancer Agent

“…Genistein treatment to BRCA1 silenced breast cancer cells, led to downregulation of GPR30 expression and the inhibition of Akt phosphorylation which induced downregulation of B1 expression, leading to cell-cycle arrest. Furthermore, the treatment also led to diminished ROS levels via upregulation of Nrf2 expression [84].…”

Molecular Changes Underlying Genistein Treatment of Wound Healing: A Review

“…The present data summarize the effects of genistein (Table 1) as natural SERM that has the unique ability to selectively act as agonist or antagonist in a tissuespecific manner. Therefore, genistein improves skin repair [47,90] and simultaneously exerts anti-cancer [105] and chemopreventive properties [106]. As a result several clinical trials combining genistein and/or its analogues with conventional chemotherapeutics have been conducted and point to the safety and efficiency of this drug [107,108].…”

Molecular Pathways of Genistein Activity in Breast Cancer Cells

“…This was demonstrated by a decrease in the expression of CYP1B1, a potential target for the aryl hydrocarbon receptor [176,177]. BRCA1-treated BC cells were silenced by genistein therapy, which also caused GPR30 expression to be downregulated, Akt phosphorylation to be inhibited, B1 expression to be downregulated, and cell cycle arrest [178]. Moreover, the therapy increased Nrf2 expression, which decreased ROS levels [178].…”