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Cruciferous vegetable compounds halt experimental lung cancer progression
Two reports published in the September 15 2005 issue of the journal Cancer Research (http://cancerres.aacrjournals.org/) revealed how isothiocyanate compounds that occur in the cruciferous family of vegetables (which include broccoli, cabbage, cauliflower and Brussels sprouts) blocked lung tumors’ progression to cancer.
Professor of Oncology at the Lombardi Cancer Center at Georgetown University Medical Center Fung-Lung Chung, PhD, and colleagues tested the compounds on mice and on human cells. In one experiment, the researchers gave mice a chemical combination that induces potentially cancerous lung tumors, and counted the number of adenomas (benign tumors) that formed in a sampling of animals after twenty weeks. The remainder of the animals were given high or low doses of one of four isothiocyanate derived compounds: phenethyl isothiocyanates, sulforaphane, phenethyl isothiocyanate-N-acetylcysteine, or sulforaphane-N-acetylcysteine for 22 additional weeks.
The researchers found that mice who received the compounds experienced reduced progression from adenoma to adenocarcinoma (malignant tumors). Nineteen percent of the tumors in mice who received the higher dose of phenethyl isothiocyanate and 13 percent of those in the higher dose phenethyl isothiocyanate-N-acetylcysteine group developed into malignancies, while 42 percent in the group that received no isothiocyanate compounds were malignant. In the group that received sulforaphane-N-acetylcysteine, 11 percent of the tumors in the low dose group and 16 percent in the high dose group had developed into adenocarcinoma.
In the study involving human cell cultures that were genetically modified to emulate cancer by growing quickly, administration of phenethyl isothiocyanate-N-acetylcysteine induced increased programmed cell death, suggesting that its use may arrest rapidly growing lung cancers.
Dr Chung commented, "These studies provide significant insight into the mechanisms of lung cancer prevention and suggests ways the process can be slowed down after exposure has already occurred. We still need to do more research, but it may be that an agent containing these ingredients could, to some degree, help protect people who have developed early lung lesions due to smoking. In any case, we know that eating vegetables is generally good for us, and that some studies have shown they help lower a person's risk of developing cancer."
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A report to be published in the September 2005 issue of the journal Cancer, Epidemiology, Biomarkers and Prevention (http://cebp.aacrjournals.org/) revealed the finding of researchers at the University of California, San Francisco (UCSF) that consuming a lot of vegetables and fruits is associated with half the chance of developing pancreatic cancer than that experienced by people whose intake is low. The study is one of the largest of its kind to date.
Onions, garlic, beans, yellow vegetables, dark leafy vegetables and cruciferous vegetables (broccoli, cauliflower, Brussels sprouts) were vegetables associated with the greatest amount of protection against pancreatic cancer risk. Although eating fruit was associated with a lesser degree of risk reduction, citrus fruits offered more protection than other fruits.
N-acetylcysteine (NAC) has both chemopreventive and therapeutic potential in malignancies arising in the lung, skin, breast, liver, head, and neck (van Zandwijk 1995; Izzotti 1998). NAC is effective in inhibiting tumor cell growth in melanoma, prostate cells, and astrocytoma cell lines (the latter is a primary tumor in the brain) (Albini et al. 1995; Arora-Kuruganti et al. 1999; Chiao et al. 2000). Neovascularization (new blood vessel growth) is crucial for tumor mass expansion and metastasis. NAC inhibited invasion and metastasis of malignant cells by up to 80% by preventing angiogenesis (De Flora et al. 1996).
In a study on men from Japan, China, and the United States, it was shown that legumes, including soy, reduce the incidence of prostate cancer by 38%. Eating yellow-orange vegetables reduces it 33%, and cruciferous vegetables reduce it 39%.
Glucosinolates (appearing in cruciferous vegetables) can inhibit, retard, or even reverse experimental multistage carcinogenesis (Fimognari et al. 2002). As enzymatic processes hydrolyze glucosinolates, isothiocyanates are released, including sulphoraphane. Sulphoraphane wields a strong arm against cancer, promoting apoptosis, inducing Phase II detoxification enzymes, increasing p53 and participating in the regulatory mechanisms of the cell's growth cycle. Necrosis (localized death of diseased tissues) is typically observed after prolonged exposure to elevated doses of sulphoraphane.
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