Chemicals in cruciferous vegetables, such as broccoli, watercress, cabbage and cauliflower, appear to stop human prostate cancer cells from growing in mice by affecting the expression of proteins, says a University of Pittsburgh Cancer Institute study, abstract number 5601, being presented today at the annual meeting of the American Association for Cancer Research, at the Washington Convention Center in Washington, D.C.
"The contribution of diet and nutrition to cancer risk, prevention and treatment have been a major focus of research in recent years because certain nutrients in vegetables and dietary agents appear to protect the body against diseases such as cancer," said Shivendra Singh, Ph.D., lead investigator and professor of pharmacology and urology at the University of Pittsburgh School of Medicine. "From epidemiologic data, we know that increased consumption of vegetables reduces the risk for certain types of cancer, but now we are beginning to understand the mechanisms by which certain edible vegetables like broccoli help our bodies fight cancer and other diseases."
Dr. Singh's study is based on phytochemicals found in several cruciferous vegetables called isothiocyanates (ITCs), which are generated when vegetables are either cut or chewed. His laboratory has found that phenethyl-ITC, or PEITC, is highly effective in suppressing the growth of human prostate cancer cells at concentrations achievable through dietary intake of cruciferous vegetables.
In seeking to further define the mechanisms by which PEITC induces apoptosis, or programmed cell death, mice were grafted with human prostate tumors and orally administered a small amount of PEITC daily. After 31 days of treatment, the average tumor volume in the control group that did not receive PEITC was 1.9 times higher than that of the treatment group. In addition, a pro-apoptotic protein called Bax appeared to play a role in bringing about apoptosis by PEITC.
"Our next step is to design clinical trials to determine the efficacy of PEITC for prostate cancer prevention in men," said Dr. Singh.
The study was supported by a grant from the National Cancer Institute. Co-investigators include Stanley W. Marynowski, Jr., Dong Xiao, Ph.D., Karen L. Lew, Yan Zeng, Rajiv Dhir, M.D., and Hui Xiao, Ph.D., all with the University of Pittsburgh Cancer Institute.
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