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.

    虽说人们一早知道吃十字花科的蔬菜,如西兰花,能帮助预防乳癌,但究竟是哪种物质在主动抑制癌细胞的扩散,人们对此却所知甚少 —— 直到现在。

    加州大学的科学家在周二宣布,他们的最新研究揭示了这种治疗能力在细胞层次上的工作机理。

    研究结果已经在这个月的Carcinogenesis杂志上发表。

    “乳癌可以通过进食如卷心菜及其近亲西兰花和白菜花等十字花科蔬菜来预防。”作者Olga Azarenko说道,“这些蔬菜含有称为异硫氰酸盐的化合物,我们相信在这些蔬菜中,就是它们在承担预防和抗击癌症的职责。”

    他们的研究集中在这其中的一种化合物,被称为莱菔硫烷或SFN的抗癌作用上。已经证明,它能减少在动物身上由化学致癌物诱导的乳房肿瘤的发病率和扩散速率。它也能抑制人工培养的人类乳癌细胞的生长。

    研究人员发现了一个令人惊奇的事实,SFN抑制人类肿瘤细胞扩散的机制,跟抗癌药物抑制细胞分裂的方法相似。然而SFN的药性要比其他提取自植物的药物的药性要弱得多,因此毒性也要比它们小得多。

    “SFN也许是一种有效的癌症预防物质,因为它会抑制癌症前期细胞的扩散并将它们杀死,”文章作者说道。它也可能用作抗癌药物的添加剂,在不增加毒性的前提下提高杀死肿瘤细胞的效率。