英语听力文摘 漫步的细胞
漫步的细胞
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.
癌症的危险因素主要在于癌细胞转移。换而言之，癌细胞不会老实地待着，可以从原发部位转移到身体其他部位。科学家苦心研究转移细胞的原理，希望能抑制癌细胞“迁移”。
无论是“冲锋陷阵”抵御感染的免疫细胞，还是在“迁移”的癌细胞，它们运动的基本原理是相同的。除了血细胞，其他细胞均由纤维物质细胞外基质包围。移动的细胞采用点对点附着体系，就像小钩一样捕捉构成细胞外基质的物质。
基本而言，细胞顺着细胞外基质移动，一旦发现血管或淋巴管，穿透血管和淋巴管，这样就畅通无阻了。因为淋巴管壁很薄，极易穿透，所以通过淋巴的检查可以诊断癌症。
而关键不仅仅是找出所有因素影响细胞自由运动的化学反应，还要明白如何能有选择地控制化学反应。因为细胞运动对于伤口愈合和抵抗疾病都至关重要，完全抑制细胞运动并不可取。科学家必须解决如何抑制某些部位的运动，比如恶化的肿瘤周围的细胞外基质。
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