英語聽力文摘 漫步的細胞
漫步的細胞
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胞轉移。換而言之，癌細胞不會老實地待著，可以從原發(fā)部位轉移到身體其他部位。科學家苦心研究轉移細胞的原理，希望能抑制癌細胞“遷移”。
無論是“沖鋒陷陣”抵御感染的免疫細胞，還是在“遷移”的癌細胞，它們運動的基本原理是相同的。除了血細胞，其他細胞均由纖維物質細胞外基質包圍。移動的細胞采用點對點附著體系，就像小鉤一樣捕捉構成細胞外基質的物質。
基本而言，細胞順著細胞外基質移動，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。
而關鍵不僅僅是找出所有因素影響細胞自由運動的化學反應，還要明白如何能有選擇地控制化學反應。因為細胞運動對于傷口愈合和抵抗疾病都至關重要，完全抑制細胞運動并不可取?？茖W家必須解決如何抑制某些部位的運動，比如惡化的腫瘤周圍的細胞外基質。
