Disorderly cancer:
Classically cancer is thought to be a growth produced by a change in the DNA of a cell such that it grows and divides repeatedly engendering a large number of progeny that have escaped the normal controls the body has that usually prevent such things. Eventually the abnormal cells destroy the host.
It is, to quote Hamlet, a custom honored more in the breach than in the observance. That central dogma seems always to be under challenge. At last so it seems from my perspective. This is in contradistinction to the usual wail I here that science is dominated by rigid paradigms, prescriptions for thinking about things, that one challenges at ones peril. With cancer any change of thinking that offers a better treatment is pretty generally welcome. It’s like the communist official who approved the budget item for jails but rejected the one for better schools. He said he thought he himself was more likely to end up in jail than go back to school. (I miss the Russians as bogymen. They had a sense of humor.) Researchers know that having to cope with cancer some day is not a remote possibility.
So there is a new challenge. (Clonal Clues Reveal Cancer Chaos NATURE vol. 492 no. 7429 December 20/27 2012 page 315 reviewing John Dick et al. University of Toronto Science http://dx.doi.org/ 10.1126/science.1227670 (2012)) What they have shown is that cancer cells with identical DNA (scratch that, with DNA directly descended from the same DNA) can have different biological behaviors.
Any living thing must retain its organization in order to continue. Cancer gets disorganized. You can often recognize that under the microscope. Look at a tissue and, if you have been instructed, you can see kind of how it is set up to do its business. Cancer is a worst than useless blob. It may vary from place to place within a mass or like leukemia it may present a boring array of almost identical cells where there should be great variety and specificity.
The implication of the study – that cancer is not totally guided in its biology by its DNA – comes with a bit of a caveat. One of the functions of a cell is to assure that DNA will be faithfully replicated. If the mechanism for that is faulty, then it does not follow that sister cells have identical DNA. But that is a quibble that can, and surely will, be addressed and resolved in the not too distant.
But what they are suggesting is, more or less, that it is epigenetic change that is determining such things as whether a cancer will spread to distant sites or whether it will respond to treatment. These are matters of great moment.
So there is now it seems to me greater urgency to understand epigenetic change. Bring it on.
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