Autors: Huang C, Huang Y, Li J, Hu W, Aziz R, Tang MS, Sun N, Cassady J and Stoner GD

Research Institute: Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York (USA)

Publication: Cancer Resarch. 2002 December 1;62(23):6857-63

Epidemiological evidence illustrates that fruit and vegetables contain anticancer phytochemicals. It is estimated that the daily consumption of at least five portions of fruits and vegetables could reduce the cancer rates by 20 to 30% in the United States. This association between the consumption of fruits and vegetables -- such as tomato, paprika, garlic, soybeans and dry beans -- and the risk of cancer has also been illustrated with scientific in-vivo and in-vitro studies. Previous studies with rodents have shown that black raspberry has anticancer properties and inhibit the development of esophageal and colon cancer, induced by carcinogens. An in-vitro study with epidermal cells has also illustrated that organic extracts from black raspberry inhibit the induced cell transformation. The exact molecular mechanism of this protective action was still unclear and was the subject of this in-vitro study. Mouse epidermal cells were exposed to the carcinogen benzo(a)pyrene diol-epoxide and treated with several organic blackberry extracts.

The researchers found that pre-treatment with several black raspberry extracts resulted in the inhibition of activated protein-1 (AP-1) and nuclear factor kappa-B, two proteins having important roles in tumor growth. Post-treatment did not result in inhibition of these proteins. The inhibitory effect was caused by inhibition of mitogen activated protein kinase and subunit kappa-B phosphorylation. None of the black raspberry extracts had an influence on the activation of tumor protein 53 (TP53), which is a transcription factor that regulates the cell cycle and hence suppressor tumor growth. Benzo(a)pyrene diol-epoxide may act by initiating oxidative stress which activates AP-1 and nuclear factor kappa-B. This oxidative stress may be reduced by the antioxidants in black raspberry extracts.

The study concluded that the anticancer activity of black berry extracts is probably caused by their mediation of pathways resulting in reduced activation of activated protein-1 and nuclear factor kappa-B.