July 29, 2005
Broccoli attacks bladder cancer cellsTopics: Nutrition and Cancer
Some 63,000 people will be diagnosed with bladder cancer this year, according to the American Cancer Society. And more than 13,000 with the disease will die. But should you envision broccoli florets as doing the job?
No, we're not talking about broccoli florets acting like little pac-men (click the link to play the game), devouring cancer cells magically throughout your body. Glucosinolates are a class of phytochemicals found in certain dietary vegetables and condiments, such as broccoli and other cruciferous vegetables, which are metabolized in the body to isothiocyanates. Certain of these compounds have, in the past two decades, been determined to have many positive health effects, including carcinogen detoxification and antioxidant properties. In the last few years, they have been explored for their potential as components in a dietary cancer prevention strategy.
Glucosinolates (in broccoli, for example) are hydrolyzed by myrosinase (an enzyme found in plants and bowel microflora) to form isothiocyanates. In vivo (in the body), isothiocyanates are conjugated with glutathione and then sequentially metabolized to mercapturic acids. These metabolites are collectively designated dithiocarbamates.In this in-vitro study(in culture), researchers isolated compounds called glucosinolates from broccoli sprouts, and found that the isothiocyanates(converted from the glucosinolates) hindered the growth of bladder cancer cells. And the most profound effect was on the most aggressive form of bladder cancer they studied(this will most likely turn out to be an issue of gene expression).
In our bodies, it's the process of chewing and digestion that the glucosinolates in the broccoli are morphed into isothiocyanates - and it is the isothiocyates that are believed to play a role in inhibiting cancer. The current work of these researchers, reported on here, builds on a major study conducted six years ago by Harvard and Ohio State universities that found that men who ate two or more half-cup servings of broccoli per week had a 44 percent lower incidence of bladder cancer compared to men who ate less than one serving each week. That particular study was retrospective and was analyzed using regression analysis.
Researchers have isolated compounds from the vegetable broccoli that they believe may help prevent or slow the progress of bladder cancer. "We're starting to look at which compounds in broccoli could inhibit or decrease the growth of cancerous cells," said Steven Schwartz, a study co-author and a professor of food science and technology at Ohio State University .Cruciferous vegetables include Arugula, Broccoli, Cauliflower, Brussel Sprouts, Cabbage, Watercress, Bok Choy, Turnip Greens, Mustard Greens, and Collard Greens, Rutabaga, Napa or Chinese Cabbage, Daikon, Radishes, Turnips, Kohlrabi, and Kale. Only cruciferous vegetables contain isothiocyanates, which have been associated with a decrease in lung cancer. Also sulforaphane and indole-3-carbinol are most concentrated in cruciferous vegetables, and are linked with reducing the risk of breast, prostrate, cervical, and other cancers, as well as reducing the size and growth of some tumors.
(...) "Knowing that could help us create functional foods that benefit health beyond providing just basic nutrition."
(...) at least in the laboratory experiments. There, isothiocyanates hindered the growth of bladder cancer cells. And the most profound effect was on the most aggressive form of bladder cancer they studied.
(...) They first extracted and measured the levels of glucosinolates from broccoli sprouts. They then used a process that uses enzymes to convert the glucosinolates to isothiocyanates.
(...)While young sprouts naturally have higher concentrations of these phytochemicals than full-grown broccoli spears, eating the spears also provides health benefits, Schwartz said.
(...) He and his colleagues treated two human bladder cancer cell lines and one mouse cell line with varying amounts of glucosinolates and isothiocyanates. Even though glucosinolates are converted to isothiocyanates, the researchers wanted to know if the former would have any effect on controlling the growth of cancer cells.
(...) the isothiocyanates(only) decreased proliferation in all three cell lines. The strongest effect was on the most aggressive of these lines - human invasive transitional cell carcinoma.
(...) "There's no reason to believe that this is the only compound in broccoli that has an anti-cancer effect," said Steven Clinton, a study co-author and an associate professor of hematology and oncology at Ohio State. "There are at least a dozen interesting compounds in the vegetable.
(...) "We're now studying more of those compounds to determine if they work together or independently, and what kind of effects they have on cancer cells," he added.
(...) The plant's kin, which include cabbage, cauliflower, Brussels sprouts and kale, may all contain similar disease-fighting phytochemicals.
(...) "Cruciferous veggies have an effect on other types of cancer, too," Schwartz said. "We already know that they contain compounds that help detoxify carcinogens. We're thinking more along the lines of progression and proliferation, such as once cancer starts, is there a way to slow it down?"
Selective induction of phase II enzymes in the urinary bladder of rats by allyl isothiocyanate, a compound derived from Brassica vegetables.
Transcriptome analysis of human colon caco-2 cells exposed to sulforaphane.
Posted by Richard at July 29, 2005 6:41 PM
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