From: Hal Finney (hal@finney.org)
Date: Wed Jun 18 2003 - 00:43:08 MDT
There is a pretty good (I thought) article in the July 2003 Scientific
American describing challenges to traditional theories about how cells
turn cancerous. The old idea is that it is due to an accumlation of
mutations, oncogenes which induce cancer being turned on, while cancer
suppressor genes are turned off. However now that genetic assays are
possible against cancer tumors, this model isn't working that well.
The new ideas focus on more general forms of genetic damage than
mutations. The most radical one suggests that the first thing that goes
wrong is massive chromosomal damage. When cells divide sometimes the
neat split of the chromosomes doesn't work, and the daughter cells end
up with missing or duplicated or hacked up chromosomes. Usually this
kills them, but occasionally they survive. At one stroke the behavior
of thousands of genes is changed massively. From here on the cell is
not working as designed. It has found its own path to survival, which
will often be erratic and unstable, making it much more susceptable to
further genetic damage.
The problem is that observations of tumor cells often show disrupted
chromosomes and damaged genes, but which came first? No one knows.
The article is available online at
http://www.sciam.com/article.cfm?chanID=sa006&articleID=000C24C1-2210-1EDD-8E1C809EC588EF21out,
Hal
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