While it has been known for some time that eating cruciferous vegetables, such as broccoli, can help prevent breast cancer, the mechanism by which the active substances in these vegetables inhibit cell proliferation was unknown -- until now.

    Scientists in University of California reported on Tuesday that their new research has shown how the healing power of these vegetables works at the cellular level.

    The study results was published in this month's journal Carcinogenesis.

    "Breast cancer can be protected against by eating cruciferous vegetables such as cabbage and near relatives of cabbage such as broccoli and cauliflower," said author Olga Azarenko. "These vegetables contain compounds called isothiocyanates which we believe to be responsible for the cancer-preventive and anti- carcinogenic activities in these vegetables."

    Their research focuses on the anti-cancer activity of one of these compounds, called sulforaphane, or SFN. 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.

    The researchers made the surprising discovery that SFN inhibits the proliferation of human tumor cells by a mechanism similar to the way that the anticancer drugs inhibit cell division. However SFN is much weaker than these other plant-based drugs, and thus much less toxic.

    "SFN may be an effective cancer preventive agent because it inhibits the proliferation and kills precancerous cells," said the authors. It is also possible that it could be used as an addition to anticancer drugs to increase effective killing of tumor cells without increased toxicity.

    雖說人們一早知道吃十字花科的蔬菜,如西蘭花,能幫助預防乳癌,但究竟是哪種物質在主動抑制癌細胞的擴散,人們對此卻所知甚少 —— 直到現在。

    加州大學的科學家在周二宣布,他們的最新研究揭示了這種治療能力在細胞層次上的工作機理。

    研究結果已經在這個月的Carcinogenesis雜志上發表。

    “乳癌可以通過進食如卷心菜及其近親西蘭花和白菜花等十字花科蔬菜來預防。”作者Olga Azarenko說道,“這些蔬菜含有稱為異硫氰酸鹽的化合物,我們相信在這些蔬菜中,就是它們在承擔預防和抗擊癌癥的職責。”

    他們的研究集中在這其中的一種化合物,被稱為萊菔硫烷或SFN的抗癌作用上。已經證明,它能減少在動物身上由化學致癌物誘導的乳房腫瘤的發病率和擴散速率。它也能抑制人工培養的人類乳癌細胞的生長。

    研究人員發現了一個令人驚奇的事實,SFN抑制人類腫瘤細胞擴散的機制,跟抗癌藥物抑制細胞分裂的方法相似。然而SFN的藥性要比其他提取自植物的藥物的藥性要弱得多,因此毒性也要比它們小得多。

    “SFN也許是一種有效的癌癥預防物質,因為它會抑制癌癥前期細胞的擴散并將它們殺死,”文章作者說道。它也可能用作抗癌藥物的添加劑,在不增加毒性的前提下提高殺死腫瘤細胞的效率。