Emerging research suggests that genistein, a component of soy, could protect a gene that suppresses the development of cancerous tumors. Share on Pinterest Could genistein, a soy component, be a key element in the development of better breast cancer treatments? In the past, some components of soy have been linked to various health benefits, including relief of acute menopausal symptoms such as hot flashes. At the core of some of these benefits stand isoflavones, which are plant-derived, estrogen-like compounds that can influence estrogen receptors once ingested. Soy-derived isoflavones have also been associated with a reduced recurrence of breast cancer, but their in-depth benefits are still being questioned and weighed. Now, new research from the University of Arizona Cancer Center in Tucson looks at the potential of genistein — a soy isoflavone — in halting the development of breast cancer tumors. Drs. Donato F. Romagnolo and Ornella I. Selmin, who led the study, suggest that genistein has a protective role in relation to BRCA1, which is a gene that can suppress tumor development. The researchers’ findings were recently published in the journal Current Developments in Nutrition.

BRCA1 ‘silencing’ promotes cancer Tamoxifen, an estrogren agonist — meaning that it acts by binding to estrogen receptors — is a drug often used to treat and prevent cancer. However, many breast cancer tumors are estrogen-receptor-negative, which renders hormonal therapy ineffective since these tutors lack the expression of the estrogen receptor. When breast cancer lacks not only the estrogen receptor but the progesterone receptor and the expression of a gene tied to cancer development as well, it is called “triple-negative.” “In triple-negative breast cancers,” says Dr. Romagnolo, “no targeted chemotherapy is available.” Triple-negative breast cancer has a very poor outcome, as it is particularly aggressive and resistant to most available therapies. Thus, finding a way of addressing the lack of an estrogen receptor might provide new avenues for tackling this disease. The BRCA1 gene plays a central role in the development of breast cancer. In a healthy system, it has a suppressive role, protecting against the development of cancerous tumors. When BRCA1 “malfunctions,” the first line of defense against cancer is weakened. In yet other cases, gene methylation — a process in which methyl groups are added to the genetic code — affects BRCA1 activity, rendering it “silent.” Thus, the BRCA1 gene becomes unable to act as a tumor suppressor.

Can BRCA1 be ‘unsilenced?’ For the purpose of this study, the researchers focused on the relationship between the aromatic hydrocarbon receptor (AhR) — which is a protein activated by environmental carcinogenic factors such as tobacco smoke — and BRCA1. They note that activated AhR “silences” BRCA1, rendering it harmless to cancer cells, which, in turn, leaves tumors free to develop and spread. Dr. Romagnolo notes that normally, BRCA1 interacts with estrogen receptor-alpha (ER-alpha). When BRCA1 is “silenced,” however, the connection with ER-alpha is also compromised. So, drugs that would normally act on the BRCA1-ER-alpha interaction — of which tamoxifen is one — become ineffective. Thus, Dr. Romagnolo and team were interested in seeing whether or not they could disable the effect of activated AhR, to allow BRCA1 to regain normal function.