Cancers Are Newly Evolved Parasitic Species

[GenesForLife]

Tumours can be transmitted via dodgy transplants or transfusions - I saw it on House!

One would think this would be a very rare occurence, unless the recipient was severely immuno-supressed. Successful cancer cells seem to be able to fool their own body's immune system, but it would be much harder to escape the attentions of a genetically different immune system. The reason why it works in the Tassie Devil poputation is because of their low genetic diversity; yet another example where the genetic diversity of a population is pivotal in its chances of going extinct...

Also, I remember reading a NewScientist article which suggested that everybody develops incipient cancer cells quite often, but almost all of the time, they are recognised and destroyed by the immune system. I gather that one line of cancer research is all about investigating the factors that give succesful cancer cells their ability to hide from the immune system...

Correct, some of the ways in which cancer cells can do it is to drop the markers that are being targeted by the immune system, yet another mechanism is to lose the receptors that immune cells dock onto to trigger apoptosis, one particularly devious case that's been noted involves cancer cells that are resistant to such apoptosis inducing ligands, but themselves secrete such ligands which go on to kill the immune cells that are trying to kill them to establish immune cell-free zones!

[Xamonas Chegwé]

Tumours can be transmitted via dodgy transplants or transfusions - I saw it on House!

One would think this would be a very rare occurence, unless the recipient was severely immuno-supressed. Successful cancer cells seem to be able to fool their own body's immune system, but it would be much harder to escape the attentions of a genetically different immune system. The reason why it works in the Tassie Devil poputation is because of their low genetic diversity; yet another example where the genetic diversity of a population is pivotal in its chances of going extinct...

Also, I remember reading a NewScientist article which suggested that everybody develops incipient cancer cells quite often, but almost all of the time, they are recognised and destroyed by the immune system. I gather that one line of cancer research is all about investigating the factors that give succesful cancer cells their ability to hide from the immune system...

Correct, some of the ways in which cancer cells can do it is to drop the markers that are being targeted by the immune system, yet another mechanism is to lose the receptors that immune cells dock onto to trigger apoptosis, one particularly devious case that's been noted involves cancer cells that are resistant to such apoptosis inducing ligands, but themselves secrete such ligands which go on to kill the immune cells that are trying to kill them to establish immune cell-free zones!

I saw it on House! Are you saying House is wrong?

[mistermack]

And oh, Mistermack, nobody has said that cancer is a species, they've said that every tumour is a new species, no requirement for being transmissible at all.

One thing about a species is that it has the ability to reproduce itself.
A cancer can do that, until the host dies, then it's fucked, totally extinct.

A parasite that kills its host and cannot spread further is as much a species as is one that does not kill its host and spreads further, to assert otherwise is to be absurd.

Acting like a parasite, and BEING a parasite, are two different things.

Cancer patients may feel like they have alien creatures or parasites growing inside their bodies, robbing them of health and vigor. According to one cell biologist, that’s exactly right. The formation of cancers is really the evolution of a new parasitic species.

At the moment, it seems to be you, and one cell biologist.
I don't read of experts in the field of cancer discovering new species of cancer, or drugs affecting certain species of cancer.

I stand on the requirement that a species needs to be able to reproduce for a reasonable length of time, to be called a species. One that arises and is certain to become extinct within a few decades is not what most people would term species.
Species is a wooly term anyway, but your definition sucks.

[GenesForLife]

And oh, Mistermack, nobody has said that cancer is a species, they've said that every tumour is a new species, no requirement for being transmissible at all.

One thing about a species is that it has the ability to reproduce itself.
A cancer can do that, until the host dies, then it's fucked, totally extinct.

A parasite that kills its host and cannot spread further is as much a species as is one that does not kill its host and spreads further, to assert otherwise is to be absurd.

Acting like a parasite, and BEING a parasite, are two different things.

Cancer patients may feel like they have alien creatures or parasites growing inside their bodies, robbing them of health and vigor. According to one cell biologist, that’s exactly right. The formation of cancers is really the evolution of a new parasitic species.

At the moment, it seems to be you, and one cell biologist.

I don't read of experts in the field of cancer discovering new species of cancer, or drugs affecting certain species of cancer.

I stand on the requirement that a species needs to be able to reproduce for a reasonable length of time, to be called a species. One that arises and becomes extinct within a few decades is not what most people would term species.
Species is a wooly term anyway, but your definition sucks.

You've got a citation for your stance, have you? A species is a population of interfertile organisms (if sexually reproducing) or an organism and its descendents (if not and clonality is maintained, or single organisms). That is how it is defined, if you don't like it you can bugger off. An extinct species is still a species, an unsuccessful species is still a species and if an asexually reproducing organism is distinct from its predecessor it is a new species. Get that? That is one of the definitions that is used for evolutionary biology, and insofar the neodarwinian synthesis is concerned, the most rigorous one. Your stand on it is irrelevant, and using your definition as part of evolutionary biology is a category error, and thus is absurd.

Cancer cells, which are characterised by aneuploidy, among other things, are clonally distinct from predecessors, and thus qualify under the criterion, so, in at least one scheme of classification that is regularly used to identify species, cancers qualify as new species. So what if they don't mention it as such, that is a classic non-sequitur, and going down that line of argument is plain fucking stupid. People can write articles mentioning wolves while not mentioning the species, that doesn't mean that the species definition does not apply to wolves, to use a slightly dodgy analogy.

Go look up Phylotype, and species, and read through this thread, http://www.rationalskepticism.org/creat ... oevolution

Also look at this post, which is by a proper evolutionary biologist too.

http://www.rationalskepticism.org/creat ... oevolution

Macroevolution and microevolution are actually well defined technical terms. Evolution in general is the change of allele frequencies in populations.
Microevolution is the change of allele frequencies in populations of organisms. Such change occurs whenever an organism dies or is born.
Macroevolution is the change of allele frequencies in populations of species. It occurs whenever speciation occurs (i.e. a species splits into two) or goes extinct.
There´s also somatic evolution, the change of allele freuqncies in populations of cells within organisms. It occurs whenever cells die or perform meiosis - or when they perform mitosis.

Evolutionary theory is all about predicting patterns at these different levels (it´s worth noting that these happen rather independently apart from some trivial things) and they are qualitatively different. Something to note is that these are tied to patterns: macroevolution and somatic evolution are tree-shaped, whereas micro-evolution is web-shaped. They are not tied to time - Single celled organisms incapable of horinzontal gene transfer are in fact single organism´d species as well - in these cases you can observe macroevolution in very short timespans.

Read the bolded bit again and again till you get it.

Also read this, from the same thread,

Susu, in cases of asexually reproducing organisms, wouldn't every mutation (which produces a new allele) result in macroevolutionary since they happen in species with single organisms?

Yes. That somehow slipped under my radar there.

My definition does not "suck" , it is evolutionarily rigorous, whereas your definition is neither rigorous nor widely used. Do you realize that Duesberg's paper was actually published and went through peer review?

Here is the abstract, chew on it.

Abstract

Since cancers have individual clonal karyotypes, are immortal and evolve from normal cells treated by carcinogens only after exceedingly long latencies of many months to decades-we deduce that carcinogenesis may be a form of speciation. This theory proposes that carcinogens initiate carcinogenesis by causing aneuploidy, i.e., losses or gains of chromosomes. Aneuploidy destabilizes the karyotype, because it unbalances thousands of collaborating genes including those that synthesize, segregate and repair chromosomes. Driven by this inherent instability aneuploid cells evolve ever-more random karyotypes automatically. Most of these perish, but a very small minority acquires reproductive autonomy-the primary characteristic of cancer cells and species. Selection for autonomy stabilizes new cancer species against the inherent instability of aneuploidy within specific margins of variation. The speciation theory explains five common characteristics of cancers: (1) species-specific autonomy; (2) karyotypic and phenotypic individuality; (3) flexibility by karyotypic variations within stable margins of autonomy; (4) immortality by replacing defective karyotypes from constitutive pools of competent variants or subspecies generated by this flexibility; and (5) long neoplastic latencies by the low probability that random karyotypic alterations generate new autonomous species. Moreover, the theory explains phylogenetic relations between cancers of the same tissue, because carcinogenesis is restricted by tissue-specific transcriptomes. The theory also solves paradoxes of other cancer theories. For example, "aneuploidy" of cancers is now said to be a "paradox" or "cancer's fatal flaw," because aneuploidy impairs normal growth and development. But if the "aneuploidies" of cancers are in effect the karyotypes of new species, this paradox is solved.

http://www.ncbi.nlm.nih.gov/pubmed/21666415

I'll try to procure the full paper, but until then, try repeating to yourself "A species that goes extinct is still a species" "A species that lives for a short time is still a species" " An unsuccessful species is still a species" until you get it before you expound drivel. So far your only argument is "I have an extra requirement for a species that the definition in use does not meet" , well, duh!

There is no requirement for inferences drawn from regularly accepted use of terms to meet whatever masala you add to your definitions of those terms.

Any more drivel to spout? (PS - you also committed the logical fallacies of a non-sequitur, an argumentum ad populum, and an argument from incredulity/ignorance/misattribution/irrelevant representation in media material)

[mistermack]

You've got a citation for your stance, have you? A species is a population of interfertile organisms (if sexually reproducing) or an organism and its descendents (if not and clonality is maintained, or single organisms). That is how it is defined, if you don't like it you can bugger off.

It is surprisingly difficult to define the word "species" in a way that applies to all naturally occurring organisms, and the debate among biologists about how to define "species" and how to identify actual species is called the species problem. Over two dozen distinct definitions of "species" are in use amongst biologists.

That's an awful lot of highly qualified biologists who need to bugger off then. I suspect many with better qualifications than yours. Including Charles Darwin :

Darwin wrote in chapter II of On the Origin of Species:

No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally the term includes the unknown element of a distinct act of creation.[8]

Wikipedia also said this about the definition of "species"

By definition it applies only to organisms that reproduce sexually. So it does not work for asexually reproducing single-celled organisms and for the relatively few parthenogenetic multi-celled organisms. The term "phylotype" is often applied to such organisms.

So Wikipedia has to bugger off as well, it seems.

[GenesForLife]

You've got a citation for your stance, have you? A species is a population of interfertile organisms (if sexually reproducing) or an organism and its descendents (if not and clonality is maintained, or single organisms). That is how it is defined, if you don't like it you can bugger off.

It is surprisingly difficult to define the word "species" in a way that applies to all naturally occurring organisms, and the debate among biologists about how to define "species" and how to identify actual species is called the species problem. Over two dozen distinct definitions of "species" are in use amongst biologists.

What part of the fact that the aforementioned definition is also used, especially in an evolutionary context, do you not get? From the same bloody article:

"'In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or ecological niche. "

Aneuploidy, which is a difference in similarity of DNA, qualifies as an identifier of species identity, Duesberg's statement holds true. Next?

That's an awful lot of highly qualified biologists who need to bugger off then. I suspect many with better qualifications than yours. Including Charles Darwin :

Darwin wrote in chapter II of On the Origin of Species:

No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally the term includes the unknown element of a distinct act of creation.[8]

Argumentum ad populum & Argumentum ad verecundiam, bloody well done. Looks like not comprehending evolutionary biology is not your only problem. What Darwin said is irrelevant to whether cancers can be seen as speciation events. They obviously can, and the concept has passed through peer review, and that is all that matters. My qualifications do not fucking matter, get that?

Wikipedia also said this about the definition of "species"

By definition it applies only to organisms that reproduce sexually. So it does not work for asexually reproducing single-celled organisms and for the relatively few parthenogenetic multi-celled organisms. The term "phylotype" is often applied to such organisms.

So Wikipedia has to bugger off as well, it seems.

I asked you to look up the meaning of phylotype, did I not? I'm well aware of the difference insofar traditional Linnaean taxonomy is concerned, by fucking definition of course Linnaean hierarchy doesn't apply in cases of somatic evolution or single celled asexual organisms either, that doesn't mean that they don't evolve or that speciation doesn't apply to them, category error again. For all evolutionary purposes, the phylotype is used as equivalent of the species, that is what Susu.exp has stated too, if you bother to read the thread I linked to. And oh, this statement contradicts what I quoted from Wikipedia too, so I'd be well entitled to reject your source for being self-contradictory, (the by definition thing you quoted is in conflict with what I've cited, again from wiki, and ergo the combination is absurd.)

Any more drivel forthcoming?

[GenesForLife]

The contradiction is here

A.

"'In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or ecological niche. "

B.

By definition it applies only to organisms that reproduce sexually. So it does not work for asexually reproducing single-celled organisms and for the relatively few parthenogenetic multi-celled organisms. The term "phylotype" is often applied to such organisms.

Now which one is it? B renders A false if B is true, A renders B false if A is true. If both are true then the article is absurd.

[mistermack]

Genes, your'e getting far too excited over the definition of the word. I've demonstrated clearly that there is no hard definition. You think there is.
Well, it's clearly not accepted by all. I think that you are stretching it to the limit.
And no, I didn't follow your links, because it's too tiresome, and I'm not obsessive.

As far as I'm concerned, a cancer cell is genetically almost identical to the other cells in the body of the organism. It just has a few mutations. It didn't evolve in the host, it's a rogue cell with some mutated genes. I don't consider that evolution of a species, it's just a mutation that happens and becomes extinct inside one animal.

As a human cancer cell has the genes necessary to make a human, I think it's still a human cell. That is it's species.

Like I said, it's a matter of opinion on semantics, and you are in the minority.

[GenesForLife]

Genes, your'e getting far too excited over the definition of the word. I've demonstrated clearly that there is no hard definition. You think there is.
Well, it's clearly not accepted by all. I think that you are stretching it to the limit.

The fact that there is no hard definition does not mean that under valid, accepted definitions of species, cancer cells fit the bill for new species, especially under the relevant criteria for asexually reproducing organisms, into which somatic evolution fits.

And no, I didn't follow your links, because it's too tiresome, and I'm not obsessive.

Irrelevant.

As far as I'm concerned, a cancer cell is genetically almost identical to the other cells in the body of the organism. It just has a few mutations. It didn't evolve in the host, it's a rogue cell with some mutated genes. I don't consider that evolution of a species, it's just a mutation that happens and becomes extinct inside one animal.

Actually, this is plain wrong, there is substantive evidence that massive chromosomal rearrangements, changes in copy number through segment duplication and genomic instability (as in extensive variability) is a feature of cancer cells. It is not genetically almost identical, far from it, actually. It is just that "some mutated genes" is an outdated concept that has been shown up by recent analyses. If you want citations I can drop a whole list of papers pointing to this and extensive variation from parental tissue type.

As a human cancer cell has the genes necessary to make a human, I think it's still a human cell. That is it's species.

When a new species forms, for instance take Drosophila pseudoobscura splitting into two based on assortative mating following a dietary separation barrier, the descendent population still has the genes to form members of the ancestral population, that does not mean that speciation has not occurred or that the descendent population is a new species.

Like I said, it's a matter of opinion on semantics, and you are in the minority.

Irrelevant again, the definition of cancers as species is definitely valid under some of the criteria in use today, the semantic issue arises from using definitions that don't apply and then asserting that cancers cannot be species even under the definitions that they are species under.

[mistermack]

Irrelevant again, the definition of cancers as species is definitely valid under some of the criteria in use today, the semantic issue arises from using definitions that don't apply and then asserting that cancers cannot be species even under the definitions that they are species under.

That kind of makes my point for me. I never said anywhere that there were not definitions that could be used to call a cancer a species. Look again at what I wrote :

Until contagious cancer appears, you can hardly call cancer a species.

That was clearly me giving my opinion on what I felt the word "species" should mean. Nowhere have I written that other definitions are wrong. I later pointed out that as there are so many definitions, it's down to a matter of opinion.
You on the other hand wrote down one definition, and said that if I didn't agree with it, I could bugger off.
Not really the scientific method.

[GenesForLife]

Irrelevant again, the definition of cancers as species is definitely valid under some of the criteria in use today, the semantic issue arises from using definitions that don't apply and then asserting that cancers cannot be species even under the definitions that they are species under.

That kind of makes my point for me. I never said anywhere that there were not definitions that could be used to call a cancer a species. Look again at what I wrote :

Until contagious cancer appears, you can hardly call cancer a species.

That was clearly me giving my opinion on what I felt the word "species" should mean. Nowhere have I written that other definitions are wrong. I later pointed out that as there are so many definitions, it's down to a matter of opinion.
You on the other hand wrote down one definition, and said that if I didn't agree with it, I could bugger off.
Not really the scientific method.

Sure, but the definition you were using, when commenting on fitness and success was terminology that clearly was contextually inadequate and was a misfit wrt gene flow, that equivocation was absurd. It isn't a matter of opinion alone either. Let us take your definition where persistence matters, or evolutionary success matters, that would lead to situations where a species when it was extant was a species and when it went extinct it wasn't a species, or it would lead to the idea that species that only last a short while aren't species, and that is absurd. The fact that multiple definitions exist does not mean that i)anything goes in any context and ii) that they can be absurd (which comes with improper context).

The definition I gave (and is used in evo-bio), which includes phylotypes and species, does cover all organisms and autonomously replicating entities, which is why it is generally used in the Neodarwinian synthesis; it allows expressions of gene pools in terms of gene flow, which is vital wrt fitness and speciation, in other words, that definition is intertwined with evolutionary biology, to substitute that with an alternate definition would require you to find alternative formulations of fitness, gene flow and speciation, your view as it is is incompatible with evolutionary biology, and to use that definition when talking about evolution, for instance, is again a category error.

[mistermack]

A human being's body experiences about 10,000,000,000,000,000 cell divisions in a lifetime. Each one of those cells is of a species separate to a human according to your logic, until it can't divide any more. Because what you say doesn't just apply to cancer cells. You would have to count any cell that can divide as a symbiotic species. And each one that involves even one mutation produces a separate species, according to what you say.
That's an awful lot of species. It's not how the rest of the world views it.

[GenesForLife]

A human being's body experiences about 10,000,000,000,000,000 cell divisions in a lifetime. Each one of those cells is of a species separate to a human according to your logic, until it can't divide any more. Because what you say doesn't just apply to cancer cells. You would have to count any cell that can divide as a symbiotic species. And each one that involves even one mutation produces a separate species, according to what you say.
That's an awful lot of species. It's not how the rest of the world views it.

Wrong; reason being that these are not reproductively autonomous, while cancer cells are (and the paper I linked to makes this clear) firstly, and secondly, if clonality is maintained then these cells are one phylotype, which means that every cell need not a single species even by the definitions I (and evolutionary biology per se) uses. What does not apply to cancer cells is the preservation of clonality; heterogeneity is a feature of tumours, which is not the case with normal somatic cells (i.e because any cell that does lose clonality is often eliminated, otherwise it becomes cancerous). Any more nonsensical strawmen you want to erect?

To summarize again

i) Interfertile population of sexually reproducing organisms = species.
ii) Population of asexually reproducing cells that are clonally identical = ONE phylotype.
iii) Population of asexually reproducing cells that are heterogenous = number of variants = number of phylotypes, which in evolutionary terms IS used as a substitute
for species.

[GenesForLife]

Older paper on the same topic here

Abstract

The many complex phenotypes of cancer have all been attributed to “somatic mutation.” These phenotypes include anaplasia, autonomous growth, metastasis, abnormal cell morphology, DNA indices ranging from 0.5 to over 2, clonal origin but unstable and non-clonal karyotypes and phenotypes, abnormal centrosome numbers, immortality in vitro and in transplantation, spontaneous progression of malignancy, as well as the exceedingly slow kinetics from carcinogen to carcinogenesis of many months to decades. However, it has yet to be determined whether this mutation is aneuploidy, an abnormal number of chromosomes, or gene mutation. A century ago, Boveri proposed cancer is caused by aneuploidy, because it correlates with cancer and because it generates “pathological” phenotypes in sea urchins. But half a century later, when cancers were found to be non-clonal for aneuploidy, but clonal for somatic gene mutations, this hypothesis was abandoned. As a result aneuploidy is now generally viewed as a consequence, and mutated genes as a cause of cancer although, (1) many carcinogens do not mutate genes, (2) there is no functional proof that mutant genes cause cancer, and (3) mutation is fast but carcinogenesis is exceedingly slow. Intrigued by the enormous mutagenic potential of aneuploidy, we undertook biochemical and biological analyses of aneuploidy and gene mutation, which show that aneuploidy is probably the only mutation that can explain all aspects of carcinogenesis. On this basis we can now offer a coherent two-stage mechanism of carcinogenesis. In stage one, carcinogens cause aneuploidy, either by fragmenting chromosomes or by damaging the spindle apparatus. In stage two, ever new and eventually tumorigenic karyotypes evolve autocatalytically because aneuploidy destabilizes the karyotype, ie. causes genetic instability. Thus, cancer cells derive their unique and complex phenotypes from random chromosome number mutation, a process that is similar to regrouping assembly lines of a car factory and is analogous to speciation. The slow kinetics of carcinogenesis reflects the low probability of generating by random chromosome reassortments a karyotype that surpasses the viability of a normal cell, similar again to natural speciation. There is correlative and functional proof of principle: (1) solid cancers are aneuploid; (2) genotoxic and non-genotoxic carcinogens cause aneuploidy; (3) the biochemical phenotypes of cells are severely altered by aneuploidy affecting the dosage of thousands of genes, but are virtually un-altered by mutations of known hypothetical oncogenes and tumor suppressor genes; (4) aneuploidy immortalizes cells; (5) non-cancerous aneuploidy generates abnormal phenotypes in all species tested, e.g., Down syndrome; (6) the degrees of aneuploidies are proportional to the degrees of abnormalities in non-cancerous and cancerous cells; (7) polyploidy also varies biological phenotypes; (8) variation of the numbers of chromosomes is the basis of speciation. Thus, aneuploidy falls within the definition of speciation, and cancer is a species of its own. The aneuploidy hypothesis offers new prospects of cancer prevention and therapy. Cell Motil. Cytoskeleton 47:81–107, 2000. © 2000 Wiley-Liss, Inc.

Full paper here (.PDF) http://mcb.berkeley.edu/labs/duesberg/p ... tility.pdf

[Ronja]

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