Phytoestrogens as Novel Therapeutic Molecules Against Breast Cancer

Abstract Phytoestrogens (PEs) are natural estrogen-like substances. They are subdivided into four main classes: isoflavones, lignans, stilbenes (polyphenols), and coumestans. PEs are broadly distributed in regular diet and herbs. They have multiple targets within cells, including the epigenome, that could be advantageous to the development of a chemopreventive drug. Breast cancer is one of the most common cancers found in women. It is the second leading cause of cancer-related death after lung cancer. Chemoprevention using PEs against breast cancer may be an effective approach. PEs have shown anticancer activity via mechanisms, including modulation of estrogen receptors (ERs), redox homeostasis, cell signaling pathways, regulation of the cell cycle, and inhibition of enzyme, angiogenesis, and epigenetic alterations. PEs can bind inadequately to ERs and have a special affinity for ER-β that can inhibit the transcriptional activity of ER-α. Genistein, daidzein, and resveratrol are some of the well-studied PEs. There are some critical issues in developing PEs as effective chemopreventive agents for breast cancer. Still, the multiple targets in breast cancer cells and their capability to modulate the cancer cell homeostasis may lead to the development of new, nontoxic, long-acting, and highly specific therapeutic agents.