How Foods Fight Cancer

"Compounds like sulforaphane in broccoli and resveratrol in wine have been shown to prevent cancer. They do that by signaling our bodies to ramp up the production of proteins capable of preventing damage to our DNA. We now have a good idea how that signal works,” said Dr. Andrew Mesecar, associate professor of pharmaceutical biotechnology at the University of Illinois at Chicago (UIC) College of Pharmacy (USA), following a recent study.

Two major proteins, Keap1 and Nrf2, are involved in prompting the fight against cancer when disease-preventing foods are ingested, according to the UIC researchers. Keap1, the sensor protein, detects the presence of dietary substances such as sulforaphane when they bind with its cysteine residues, one of the amino acids that make up proteins. Keap1 attaches to Nrf2, the messenger that activates the genes for the protective proteins, avoiding DNA damage.

"Earlier studies in mice suggested that natural cancer-preventing compounds worked by severing the tie between Keap1 and Nrf2, freeing Nrf2 to take action,” Dr. Mesecar remarked. "But the signaling doesn't happen this way in humans.”

The researchers discovered that in humans the connection between the two proteins is not disrupted. What is significant, the investigators reported, is the alteration of cysteines in Keap1. They discovered that one specific cysteine was among the most likely to be modified in the interaction with cancer-preventing compounds.

This finding corresponded with results from other researchers. As a result, the scientists are proposing that the alteration of only this one amino acid in Keap1 is the critical step that triggers increases of the messenger Nrf2, and as a result, increased production of the protective proteins.

Keap1 is a potential new target for drugs to combat many different types of cancer, according to Dr. Mesecar. "One way of preventing cancer may be to eat certain foods rich in cancer-preventing compounds. An alternative is identifying how these compounds work and replicating their modes of action with drugs,” noted Dr. Mesecar.

The study was published in the June 12, 2005, online edition of the Proceedings of the [U.S.] National Academy of Sciences.




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