英語聽力文摘 漫步的細(xì)胞

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漫步的細(xì)胞

A major reason why many cancers are so dangerous is that they metastasize. This means that instead of staying in one place, the cancer cells migrate from their original site to other parts of the body. No wonder that scientists are busy studying the mechanism that enables cells to move around, in hope of finding a way to control this migration.

Whether it’s an immune cell going off to battle infection, or a cancer cell making its way to a new area of the body, the underlying mechanism for its movement is the same. All non-blood cells are surrounded by a fibrous material known as the extracellularmatrix. Anyway, cells on the go use a point-to-point adhesion system, which functions like tiny hooks, to grab the materials that make up the extracellularmatrix.

So, basically, in order to move, a cell climbs hand-over-hand along the extracellularmatrix until it reaches a blood or lymphaticvessel and penetrates it. From there, it’s smooth sailing. By the way, the thinner walls of lymphaticvessels are easier to penetrate, which is why examining lymph nodes plays a major role in cancer detection.

The trick then, is not only to figure out all the factors that affect the chemical reactions that enable cells to move around, but also to figure out how to control these reactions selectively. Because cell movement is necessary for healing wounds and fighting off diseases, stopping it completely isn’t an option. Instead, scientists will have to figure out how to block movement in select locations, like in the extra-cellular matrix around growing tumors.

癌癥的危險因素主要在于癌細(xì)胞轉(zhuǎn)移。換而言之，癌細(xì)胞不會老實地待著，可以從原發(fā)部位轉(zhuǎn)移到身體其他部位?？茖W(xué)家苦心研究轉(zhuǎn)移細(xì)胞的原理，希望能抑制癌細(xì)胞“遷移”。

無論是“沖鋒陷陣”抵御感染的免疫細(xì)胞，還是在“遷移”的癌細(xì)胞，它們運(yùn)動的基本原理是相同的。除了血細(xì)胞，其他細(xì)胞均由纖維物質(zhì)細(xì)胞外基質(zhì)包圍。移動的細(xì)胞采用點對點附著體系，就像小鉤一樣捕捉構(gòu)成細(xì)胞外基質(zhì)的物質(zhì)。

基本而言，細(xì)胞順著細(xì)胞外基質(zhì)移動，一旦發(fā)現(xiàn)血管或淋巴管，穿透血管和淋巴管，這樣就暢通無阻了。因為淋巴管壁很薄，極易穿透，所以通過淋巴的檢查可以診斷癌癥。

而關(guān)鍵不僅僅是找出所有因素影響細(xì)胞自由運(yùn)動的化學(xué)反應(yīng)，還要明白如何能有選擇地控制化學(xué)反應(yīng)。因為細(xì)胞運(yùn)動對于傷口愈合和抵抗疾病都至關(guān)重要，完全抑制細(xì)胞運(yùn)動并不可取。科學(xué)家必須解決如何抑制某些部位的運(yùn)動，比如惡化的腫瘤周圍的細(xì)胞外基質(zhì)。