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【摘译】原文：Cancerous tumors might be our oldest evolutionary ancestors http://www.abovetopsecret.com/forum/thread675117/pg19 S# Z& S4 z% k5 @: B, p: J
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癌症是医学科学史上所面对最困难的敌人之一，但一个有争议的新想法可能为我们打通胜利的道路。一个科学家小组证据显示，癌症可能是一种将我们退化到最遥远的动物的祖先机制。9 p+ p6 T6 R" v
0 g$ Y( d- f8 a9 A 天体生物学家澳大利亚国立大学Charles Lineweaver和亚利桑那州的Paul Davies 提出，癌细胞是一个所谓的“活化石”，来自距今约600万年前一个关键的进化接缝的最后残余。 癌症可以追溯到多细胞动物的开始，此前需要进行一个进化的创新，即每当细胞想要开始与其他有机体协调时要停止复制。
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1 F. K3 T$ ~5 I4 B) @" ^. x癌症发生于这些非常古老的细胞复制控制故障，导致失控的细胞复制。但这里Lineweaver和Davies有了进一步的想法——他们认为癌症实际上是我们的最早的动物祖先。 他们指出，这些生物最早拥有了一些对细胞复制的控制措施，但他们缺乏对细胞生长更精确的控制。 ! e, J# b D, h, r$ M7 e) N
4 H ^* x* R0 Q$ [ M0 q3 c/ A这一假说，他们认为，比那些认为所有癌细胞都是特立独行的观点能更好地解释肿瘤的行为。他们指出血管生成，癌细胞建设血管网络将养料运入肿瘤，这表明细胞之间的合作。事实上，癌细胞可以转移到其他组织的地区，如果所有的细胞都是特立独行的癌转移行为是很难解释的。
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有时为了击败你的敌人，你必须成为你自己的敌人，用这种方式看待癌症正是我们在做的。 4 X1 @# g* L# \# [4 t$ r" N3 }
显然，辐射、或遗传因素等种种因素可以导致癌症，因此绝不会有“痊愈”。然而，这可能意味着将有一个标准的过程最终被用于清除它。 一旦我们掌握了她的代码，我们就可以开始攻击它。
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Tumours could be the ancestors of animals
2 A* E/ K/ o5 a4 R0 K11 March 2011 by Colin Barras & G/ s, b2 [( C0 y
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CANCER remains a formidable foe even 40 years after Richard Nixon officially declared war on it. A new and controversial hypothesis now offers hope that the war can ultimately be won. It suggests tumours have a limited ability to evade modern therapies - a consequence of the idea that cancer is our most distant animal ancestor, a "living fossil" from over 600 million years ago.
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Some cancers evolve resistance to a treatment within a few years. One possible explanation for this is that the cells within a tumour act independently, competing with one another via natural selection to evolve therapy-dodging innovations.
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: I m2 i4 Y2 |+ Z6 G) vAstrobiologists Charles Lineweaver at the Australian National University in Canberra and Paul Davies at Arizona State University in Tempe have an alternative explanation. They say that evidence of basic cellular cooperation within tumours suggests cancers are a throwback from the origin of the animal kingdom - and that any ability to resist modern drugs relies on an ancient and ultimately limited array of survival tactics." k2 x; F2 s6 M. n2 ?3 U
7 R0 Q/ A5 y4 w$ pTheir hypothesis builds on an old idea that suggests a link between cancer and the origin of multicellular animals, sometime before 600 million years ago. For billions of years before that point, the animals' single-celled ancestors replicated with reckless abandon. Once organisms contained multiple cells, however, replication had to become more restrained, to avoid adverse effects on the organism.
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Cancer is thought to be triggered by a malfunction of the genes that try to hold back this uncontrolled replication. But Lineweaver and Davies go further: cancer is not simply linked to the evolution of animals - it was the earliest animals. They believe these organisms had cracked the problem of runaway replication but they still lacked total control over cell growth and proliferation.6 r1 {/ a- }. t
) q3 n: o3 d7 z. H9 _0 w% }( Q% iThe hypothesis helps to explain some of the more unusual features of tumours, says Lineweaver. Some cancer cells build a network of blood vessels, a process known as angiogenesis, to bring nutrients into the tumour - evidence of tumour-wide cooperation. Other cells gain the ability to spread to other tissues, or metastasise, which is difficult to explain if all cancer cells act independently.
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: {, S0 X0 U/ l& Y- B; [) c t. Z) }Lineweaver and Davies think the genetic toolkit at work in these first animals is buried within all of us. The genes that came later might have tinkered with it, but whenever those later additions malfunction the ancient genes can revert to their initial function.5 t5 B+ r( C+ O! y2 {
5 ]$ D$ O$ z( P" _" o1 r AConsequently, a tumour is not a collection of independently evolving cells, like bacteria, with almost infinite potential to evolve resistance to therapy. It is a group of largely cooperating cells relying on a finite collection of survival strategies that were locked in place over half a billion years ago (Physical Biology, DOI: 10.1088/1478-3975/8/1/015001).# V: X. P. H# e+ a" N! h- F% ?/ h
# I! ]! a! v" y& vReactions to Lineweaver and Davies's idea vary from cautious enthusiasm to outright scepticism. Carlo Maley at the University of California in San Francisco, who studies the evolutionary processes at work in cancer, is receptive: "They make a bunch of interesting predictions," he says.! L% |% B2 a) r' s7 E
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Others are more guarded. It is an "imaginative metaphor", says Mansi Srivastava at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, who studies the evolution of genes including those involved with cancer. However, she thinks the idea of cancer as a living fossil from the dawn of animal life is a step too far. "There is no evidence to believe that the ability to develop blood vessels is an ancient feature of animals."
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Lineweaver disagrees: "Fully developed angiogenesis had to have evolved from proto-angiogenesis," he says. "I think it's clear that some form of proto-angiogenesis was very important for the earliest animals."7 t3 J* N& H5 [) w! Q+ y
2 y, d" {; i8 q5 n7 h% lGenetic profiling may soon help to test the hypothesis, says Lineweaver. The ways a particular cancer responds to treatment in different people should correlate with each other, he says, because they should share strategies for dealing with toxins that were developed in the earliest animals.
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, G2 |: y' G$ D3 n' I4 E2 {Even if cancer does have a limited ability to resist treatment, though, Maley has a reality check. If the war on cancer has taught us anything, it is that battling even a predictable cancer will remain "plenty hard" in the short term.
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发表于 2011-4-17 16:50
发表于 2011-4-17 18:10
