Contributed by Lisa Olen | 18 April, 2005 20:39 GMT
Chocolate has an ingredient that seems to exert anti-cancer properties, according to new research findings that may one day contribute to the design of novel cancer treatments. The study, carried out by researchers from the Lombardi Comprehensive Cancer Center at Georgetown University, is published in the April issue of the journal Molecular Cancer Therapeutics.
Pentameric procyanidin (pentamer), a natural compound found in cocoa, deactivates a number of proteins that likely work in concert to push a cancer cell to continually divide, the authors explain.
“There are all kinds of chemicals in the food we eat that potentially have effects on cancer cells, and a natural compound in chocolate may be one,” says the lead author, Robert B. Dickson, Ph.D., professor of oncology. “We need to slowly develop evidence about the selectivity of these compounds to cancer, learn how they work, and sort out any issues of toxicity.”
Flavonoids Offer Protection from Free Radicals
Chocolate, like many other foods, is the source of many possible anti-cancer compounds, but Dickson stresses that this research, which is part of a series of studies conducted at Georgetown on the chocolate-cancer connection, does not mean that people who eat chocolate will reduce their cancer risks or treat a current case.
Although the study was conducted in breast-cancer cell cltures, the finding potentially could apply to other cancers, Dickson said.
Chocolate is made from the beans of the cacao tree, one of the plants that is rich in natural antioxidants known as flavonoids. These antioxidants may protect cells from the damage caused by unstable molecules called free radicals, which are thought to contribute to both heart disease and cancer development.
The primary family of flavonoids contributing to the antioxidant benefit in chocolate is the procyanidins. Of the various types of procyanidins, pentamer seem to be strongest, according to a number of studies.
Stopped Breast-Cancer Cell Division
The Georgetown researchers looked at what happened when they used a purified preparation of pentamer on a variety of breast-cancer cells, compared to treatment on normal breast cells. They used a variety of tests to find and identify proteins that were deactivated in the cancer cells.
What they located were two well-known tumor suppressor genes, as well as two other proteins known to be involved in regulating the “cell cycle” — the progression of a cell from a state of being “quiet” into division and growth.
They specifically found that the breast-cancer cells stopped dividing when treated with pentamer and that all four proteins were inactivated. Furthermore, expression of one of the genes was reduced.
Master Switch Turned Off?
Dickson notes that “the novel aspect here is that a pattern of several regulatory proteins are jointly deactivated, probably greatly enhancing the inhibitory effect compared to targeting any one of the proteins singly. That is also why the compound seems to work on cancer cells, irrespective of whether any of these single genes are mutated, which often happens in cancer cells.”
The researchers don’t know why pentamer deactivates these proteins simultaneously, stopping the cell cycle, he adds. “We don’t know at a fundamental level whether a master switch that triggers cell growth is turned off or whether the chocolate compound exerts multiple independent effects on diverse cellular processes. That will be the subject of future studies here.”