Broccoli, soy anti-cancer benefits suggested
certain cancers, and researchers have now proposed a mechanism to
explain how such foods may offer protection.
Researchers from the University of California, Los Angeles report that diindolylmethane (DIM), a digestive product from cruciferous vegetable digestion, and genistein, a major isoflavone in soy, may interfere with the "CXCR4/CXCL12 axis," known to play a central role in the spread of breast cancer and is also thought to play a role in the development of ovarian cancer.
And the news may offer opportunities to the supplements industry since the doses used are comparable to use of a high dose of supplements, said researchers Erin Hsu and Oliver Hankinson from UCLA, but is unlikely to be achievable through consumption of food alone.
Epidemiological and animal studies have shown that diets high in cruciferous vegetables and soy result in less instances of certain cancers, especially breast and ovarian cancer.
Primary cancer cells are said to express very high levels of the CXCR4 chemokine receptor on the surface of their cells, and the organs to which these cancers spread secrete high levels of the CXCL12 chemokine ligand.
In other words, this attraction between CXCR4 and CXCL12 draws cancer cells to the organs they spread to.
This chemical attraction is thought to play a role in the development of over 23 different types of cancer.
Presenting their research at the Annual Meeting of the American Association for Cancer Research Hsu and Hankinson report that exposing breast and ovarian cancer cells to pure DIM and genistein decreased the levels of the CXCR4 and CXCL12 proteins in a dose-dependent manner.
To further investigate if the compounds had any effect on the spread of cancer cells, cancer cells were placed in one end of a compartment and watched how they moved toward CXCL12 at the other end.
"The cells degrade the extracellular matrix in the upper compartment in order to move toward CXCL12 in the lower compartment, a system that represents a cell culture model for invasiveness," explained Hsu.
However, exposure with either DIM or genistein cut movement by 80 per cent, said the researchers.
"Our data suggest that one mechanism whereby DIM and genistein protect against breast and ovarian cancers is through the repression of CXCL12 and/or CXCR4, thereby lowering the invasive and metastatic potential of these cells," they said.
"We have also tested other phytochemicals and seen similar effects, indicating that this mechanism may mediate protective effects of other vegetable products as well," said Hsu.
Hsu said that the results from the in vitro experiments now need testing in vivo before any more definitive links between the compounds and potential anti-cancer effects can be achieved.
Toxicity levels should also be investigated.
Source: Annual Meeting of the American Association for Cancer Research April 2007, Abstract 4217
"A novel mechanism for the chemoprotection by 3,3-diindolylmethane (DIM) and genistein for breast and ovarian cancers" Authors: E.L. Hsu, O. Hankinson
