Study: Cancer Prevention May Begin at the Vegetable Stand

Mothers have a new reason to make their children eat their greens, and it is not just "because I told you so."

A recent article published by Georgetown researchers in The Journal of Medicinal Chemistry suggests that cruciferous vegetables such as broccoli, cabbage and watercress contain compounds that may block the growth of cancer cells.

The compounds — called isothiocyanates, or ITCs — work by binding to defective p53 proteins, which are found in approximately half of all cancer types. While normal p53 proteins are found in healthy human cells and prevent abnormal cell growth, mutated p53 proteins can create conditions favorable for the genesis of tumors, especially in cancer patients.

The study was conducted at Georgetown's Lombardi Comprehensive Cancer Center by first-time co-authors Anthony J. Di Pasqua, Ph.D., and Xiantao Wang, Ph.D., both of whom worked  under the guidance of ITC expert  Fung-Lung Chung. Georgetown graduate Charles Hong (COL '10), was an assistant for the study.

Explaining the research to The Hoya, Di Pasqua said that the study noted that certain kinds of ITCs were especially resilient in fighting only abnormal protein cells, leaving healthy p53 proteins intact.

"We concluded from our studies that depending on its structure, ITCs can robustly deplete mutant p53 protein, and that this depletion appears to be specific to mutant forms of p53," Di Pasqua said. "This is important because approximately half of all cancers carry p53 mutations, and there is evidence that mutant p53 promotes tumor genesis."  

Seventeen different types of ITCs, both natural and synthetic, were examined in the study. Of those, a synthetic ITC called 2,2-diphenylethyl ITC was one of the most successful at depleting mutant p53 proteins. It also induced the greatest extent of apoptosis — self-destruction by a cell — in breast cancer cells containing mutant p53.

"Several natural ITCs did perform very well in tests, particularly garden cress and other dark green leafy vegetables," Di Pasqua said.

Previous studies had observed that ITCs seemed to prevent the growth of cancer cells, but researchers now recognize the way in which ITCs bind to mutant p53 proteins, preventing them from instigating abnormal cell growth.

With a more developed understanding of ITC abilities, doctors may make the use of natural or synthetic ITCs an important component in the treatment of certain types of cancer in the future. Di Pasqua believes that the compounds have the potential to be used as chemopreventive and chemotherapeutic agents.

In addition to the preventative properties found in ITCs, cruciferous vegetables offer a number of other documented elements that aid in cancer treatment.

"Another benefit of consuming cruciferous vegetables is that they contain fiber, lutein and carotenoids along with the ITCs, and all of these substances fight cancer as well," Di Pasqua said.