cancer from a evolutionary perspective.

thorium1010

Okay, so i have read one or two articles about cancer from a evolutionary perspective. However it still its not clear how cancer cells have a particular advantage in our body ?
Is it that cancer cells have increase their survivability by rapidly multiplying - are there any examples of this in nature (such as rapidly multiplying colony of bacteria outgrowing nearby colonies ) .

Here' s an article (abstract ) that says cancer rates are higher in humans compared to larger animals -

http://www.ncbi.nlm.nih.gov/pubmed/21296451

Would welcome any comments, resources on the subject.

chemisttree

Why do you think they would need to have an advantage? Don't cancers generally occur long after humans have reached sexual maturity?

Monique

See my signature, mutations are needed for evolution. One of the side-effects of mutations is tumor formation, not good for the organism.

thorium1010

I think that sexual maturity thing is not correct, as children or for that matter young adults are affected by cancer.

Thanks monique, i will look into it.

mishrashubham

Why do you think survivability of cancerous cells "inside' the body would have any evolutionary implications. Clearly cancerous cells are cases of deviation from the usual cell cycle. If you consider fitness of a gene to somehow cause the production of more copies of itself, then the cancerous cells are not doing themselves any good by destroying the organism in which they are formed since their genes wouldn't be carried forward to next generation. (Competition arises because of the slight mutational difference in the genotypes of the normal and cancer cells)

He did use the word 'generally' so he isn't wrong.


http://www.ncbi.nlm.nih.gov/books/NBK1559/

chemisttree

... and of course there is the little gem in the opening line of your quoted text, "The evolution of multicellularity required the suppression of cancer."

Kind of argues against your assumed point, "...still its not clear how cancer cells have a particular advantage in our body?"

mishrashubham

You've lost me there.

chemisttree

What confused you? That multicellularity requires the suppression of cancer cells vs. cancer cells offer an advantage? How about if cancer cells afford some advantage then why should it be necessary they be suppressed? Why suppress the 'advantage'?

mishrashubham

By that statement, I think he implied cancer cells having an advantage inside the body and not them offering an advantage to their host.

chemisttree

It was in context of evolution... host is all that matters. Do rapidly-dividing epithelial cells have an 'advantage' over a brain cell?

mishrashubham

Exactly my point too. He seems to be under the impression that the cancer cells having the ability to rapidly multiply inside the body somehow contributes to its evolutionary stability.

thorium1010

Yes, multicellualrity requires suppression of not only cancer cells lot of other things for the organism to survive. I don't know where in my post did you get an impression that i claimed cancer cells are helpful or advantageous to the host . I was interested to know how cancer have a particular advantage in our body. I know there are many mechanisms that keep a check on cells which are damaged to stop the progression to cancer.


If you look at my post again , I said, it was not very clear how cancer cells had a particular advantage over regular cells and then ended it with some sort of question

My premise was to set up some sort of discussion on the subject which could offer some ideas on the subject . I did not say only by rapidly multiplying cancer cells have an advantage. But, it is one of those characteristic of a cancer, someone would easily recognize . And no not all cancers are rapidly multiplying (but most are).

O k, is it because i used the word survivability that might have led to the confusion of interpreting it as stability.

As for this, it seems out of point. I never argued or was under the impression that cancer cells have higher stability than regular cells.

Ygggdrasil

When cancer biologist speak of cancer evolution, they refer to changes in the cancer cells' genome that allow the cancer to outcompete the body's cells for resources, grow into tumors, metastasize, can colonize other areas of the body. Obviously, the analogy is not perfect as the cancer cells ultimately doom themselves by slowly killing the host, but in certain contexts, it is useful to think of cancer progression as an evolutionary process. For example, there are some useful analogies between how pathogens acquire drug resistance and how tumors become resistant to chemotherapy.

There are, however, cases where thinking of the development of cancerous cells as an evolutionary process is very apt. For example, some cancers have evolved into transmissible diseases that can spread from animal to animal and parasitize their hosts:

https://en.wikipedia.org/wiki/Transmissible_cancer

Ygggdrasil

If you are interested in the changes required to convert normal cells into cancer cells, and how these changes allow the cancer cells to proliferate within the body, you should read the following two articles by Hanahan and Weinberg, describing the "Hallmarks of Cancer":

"We have proposed that six hallmarks of cancer together constitute an organizing principle that provides a logical framework for understanding the remarkable diversity of neoplastic diseases. Implicit in our discussion was the notion that as normal cells evolve progressively to a neoplastic state, they acquire a succession of these hallmark capabilities, and that the multistep process of human tumor pathogenesis could be rationalized by the need of incipient cancer cells to acquire the traits that enable them to become tumorigenic and ultimately malignant."

In the original article from 2000, the authors discuss identify six properties are essential for cancer progression: sustaining proliferative signaling, evading growth surpressors, activating invasion and metastasis, enabling replicative immortality, inducing angiogenesis, and resisting cell death. The authors published an update in 2011 which incorporates new results from the past ten years to provide new insights into other hallmarks of cancer.

Hanahan and Weinberg. 2000. The Hallmarks of Cancer. Cell, 100: 57. doi:10.1016/S0092-8674(00)81683-9
Hanahan and Weinberg. 2011. The Hallmarks of Cancer: The Next Generation. Cell, 144: 646. doi:10.1016/j.cell.2011.02.013