Radiosensitization of Prostate Cancer by Soy Isoflavones

A trend in investigating the use of several nutritional compounds for cancer chemoprevention has revealed that phytochemicals demonstrated anti-cancer properties by inhibiting signal transduction pathways essential for cancer cell proliferation, tumor growth, invasion and metastasis. Emerging evidence suggests that the anti-proliferative and anti-oxidant effects of some of these dietary agents could be utilized to both potentiate the response of cancer cells to radiotherapy and reduce radiation-induced toxicity to normal surrounding tissues. Using pre-clinical orthotopic models of prostate cancer, studies on the combination of soy isoflavones with tumor irradiation demonstrate a synergistic anti-cancer effect between these two modalities and emphasize the potential and safety of dietary factors to improve conventional radiotherapy for a better control of tumor growth and metastasis. The goal of this review is to focus on the role of soy isoflavones as potent radiosensitizers for prostate cancer and other malignancies. We will discuss molecular pathways regulated by soy isoflavones that inhibit survival pathways activated by radiation and ultimately drive the cells to cell death both in vitro and in vivo in pre-clinical models.