Genistein Prevents Spread of Prostate Cancer in a Mouse Model

Exploiting a mouse model for human prostate cancer that was developed for testing anti-metastatic drugs, cancer researchers found that the soybean isoflavone genistein prevented prostate tumor metastasis.

Genistein had been shown in previous research to have anti-cancer properties. It exhibited antioxidant, antiangiogenic, and immunosuppressive activities. Genistein bound to and inhibited protein-tyrosine kinase, thereby disrupting signal transduction and inducing cell differentiation. Genistein also inhibited topoisomerase-II, leading to DNA fragmentation and apoptosis, and induced G2/M cell cycle arrest.

In the current study, investigators at Northwestern University (Evanston, IL, USA) injected aggressive human prostate cancer cells (PCa cells) into a line of inbred athymic mice. Without treatment, the PCa cells formed lung micro-metastasis by four weeks in more than 80% of the mice. However, if the mice were fed on a diet containing a concentration of genistein equivalent to that consumed by a human adult male on a soybean enriched diet, metastasis of prostate cancer to the lungs was decreased by 96%.

Additional results published in the March 15, 2008, issue of the journal Cancer Research revealed that genistein induced nuclear morphometric changes in the PCa cells indicative of increased adhesion (i.e., decreased detachment) but did not alter growth of the original prostate tumor. Synthesis of proteins linked to cell motility was increased, but these proteins were ineffective in eliciting metastasis.

"These impressive results give us hope that genistein might show some effect in preventing the spread of prostate cancer in patients,” said senior author Dr. Raymond Bergan, professor of experimental therapeutics at Northwestern University. "Diet can affect cancer and it does not do it by magic. Certain chemicals have beneficial effects, and now we have all the pre-clinical studies we need to suggest genistein might be a very promising chemopreventive drug.”


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