An article published in the December, 2008 issue of the journal Carcinogenesis <http://carcin.oxfordjournals.org/> explains how broccoli and other cruciferous vegetables protect against cancer of the breast. Increased intake of cruciferous vegetables, which also include cauliflower, Brussels sprouts and cabbage, has been associated with a lower risk of breast and other cancers, yet their mechanism of action against the disease has not been thoroughly explored.
Researchers at the University of California Santa Barbara laboratories of Professors Leslie Wilson and Mary Ann Jordan studied the effects of sulforaphane, one of a group of cruciferous vegetable compounds known as isothiocyanates, on cultured human breast cancer cells. They found that sulforaphane inhibits tumor cell proliferation in a manner similar to that of taxol and vincristine, which are powerful anticancer drugs. The drugs help prevent cell division during a process known as mitosis, in which duplicated DNA in the cells’ chromosomes is distributed to two daughter cells. The chromosomes are separated with the assistance of tube-like structures known as microtubules, whose function is interfered with by taxane and vinca alkaloid drugs. Sulforaphane similarly interferes with microtubule function during mitosis, but its action is weaker than the pharmaceutical agents, lessening the potential for toxicity.
"Breast cancer, the second leading cause of cancer deaths in women, can be protected against by eating cruciferous vegetables such as cabbage and near relatives of cabbage such as broccoli and cauliflower," first author and UC Santa Barbara graduate student Olga Azarenko commented. "These vegetables contain compounds called isothiocyanates which we believe to be responsible for the cancer-preventive and anticarcinogenic activities in these vegetables. Broccoli and broccoli sprouts have the highest amount of the isothiocyanates.”
"Our paper focuses on the anticancer activity of one of these compounds, called sulforaphane, or SFN," Dr Azarenko stated. "It has already been shown to reduce the incidence and rate of chemically induced mammary tumors in animals. It inhibits the growth of cultured human breast cancer cells, leading to cell death."
"Sulforaphane may be an effective cancer preventive agent because it inhibits the proliferation and kills precancerous cells," concurred Dr Wilson, who is a professor of biochemistry and pharmacology at UC Santa Barbara. The compound also has potential as an additive therapy to antimitotic drugs to enhance their effects without increasing toxicity.