Black raspberries may reduce colorectal cancer risk: Mouse study
Researchers from the University of Illinois at Chicago report that supplements of the berries were associated with a 45 percent reduction in the incidence of colorectal tumors, and a 60 per cent reduction in the number of tumors in a specific strain of mouse engineered to develop intestinal tumors.
The study’s findings need to be replicated in additional studies, and particularly in human studies before any firm conclusions can be drawn, but it does support a small but growing body of science linking black raspberries and the polyphenolic compounds they contain to a potential reduction in the risk of a variety of cancers, most notably esophageal cancer.
The UIC researchers are indeed looking to take the research to the next stage and hope to obtain funding to begin clinical trials in humans, said lead author Dr Wancai Yang, an assistant professor of pathology at the UIC College of Medicine.
Berries and genes
A study published in2008 by Gary Stoner and his colleagues at Ohio State University (Cancer Research, Vol. 68, pp. 6460-6467) found that the berry may potentially help prevent certain cancers by acting on multiple gene targets. The Ohio study – which also used animals - found that over 2,000 genes were affected in the esophagus of animals when they were exposed to a carcinogen, but normal function was restored in 462 genes after supplementation with freeze-dried black raspberries.
“We have clearly shown that berries, which contain a variety of anticancer compounds, have a genome-wide effect on the expression of genes involved in cancer development,” said Dr Stoner in 2008.
“This suggests to us that a mixture of preventative agents, which berries provide, may more effectively prevent cancer than a single agent that targets only one or a few genes,” he added.
Writing in the November issue of Cancer Prevention Research, the UIC researchers examined the potential activity of black raspberries in the colon and rectum of two mouse models of colorectal cancer.
The first strain – Apc1638 – is engineered to develop intestinal tumors, while the second strain – Muc2 – has a specific gene knocked out, which causes colitis – inflammation of the large intestine that may contribute to the development of colorectal cancer.
Both sets of mice were randomized to receive a Western-style diet, high in fat and low in vitamin D and calcium, or the same diet with an additional 10 percent freeze-dried black raspberry powder.
After 12 weeks of study, the researchers report that Apc1638 mice receiving the additional raspberries displayed a 45 percent reduction in tumor incidence and a 60 percent reduction in the number of tumors. When Dr Yang and his co-workers looked at the genetics, they saw that the black raspberries were associated with an inhibition of tumor development by suppressing a protein, known as beta-catenin, which binds to the APC gene and promotes tumor development.
Furthermore, in the Muc2 mice fed the berries a reduction in chronic inflammation was observed, and the tumor incidence and the number of tumors were both reduced by 50 percent, said the researchers.
"We saw the black raspberry as a natural product, very powerful, and easy to access," said Dr Yang.
Source: Cancer Prevention Research
November 2010, 3(11); 1443–50, doi: 10.1158/1940-6207.CAPR-10-0124
“Black Raspberries Inhibit Intestinal Tumorigenesis in Apc1638+/− and Muc2−/− Mouse Models of Colorectal Cancer”
Authors: X. Bi, W. Fang, L-S. Wang, G.D. Stoner, W. Yang