Chocolate compound stops
cancer cell cycle in lab
18/04/2005 - A natural compound found in cocoa deactivates a number of
proteins that are probably behind the continual division of cancer cells, report
The compound pentameric procyanidin has previously been shown to stop breast
cancer progression in lab studies
the mechanism was unknown.
Writing in the April issue of Molecular Cancer Therapeutics (vol 4, issue
4, pp537-46), a team from the Lombardi
Cancer Center at Georgetown University explain that the compound appears to work
on several different
involved in the cancer.
Although the study was conducted in breast cancer cell cultures, the finding
could potentially apply to other cancers, said lead author Robert B. Dickson.
However he added: "We need to slowly develop evidence about the selectivity
of these compounds to cancer, learn how they work, and sort out any issues of
The research, which is part of a series of studies conducted at Georgetown on
the chocolate-cancer connection, is being funded by confectionery giant Mars.
Cacao beans are rich in natural antioxidants known as flavonoids. These
antioxidants may protect cells from the damage caused by 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, and of the various types of procyanidins,
pentamer seem to be strongest, according to a number of studies.
The Georgetown researchers tested a purified preparation of pentamer on a
variety of breast cancer cells, compared to treatment on normal breast cells.
two well known tumour 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 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.
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
The researchers can not yet explain why pentamer deactivates these proteins
simultaneously, stopping the cell cycle.
"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."