Subject: Re: Cancer and gene mutation: A real or fictious relationship?
On Tue, 16 Mar 2004 William Morse wrote:


cncabej{at}aol.com (CNCabej) wrote in
news:c30p1v$2t8e$1{at}darwin.ediacara.org: 

> Cancer is generally considered to be an abnormal growth of cells
> caused by mutations in DNA induced by carcinogenic substances, viral
> oncogenes, ionizing radiations etc. Although evidence has been
> insufficient, and it has also been argued that often this relationship
> was not seen, the mutational theory of cancer is the explanation we
> find in every textbook. A recent experiment raises doubts about the
> validity of the dogma. Investigators show that mutation in the 
> Ha-ras-1 gene is sometime found in normal mammary gland and is absent
> in cancerous cells. Here is the abstract published in the Journal of
> Cell Science on March , 2 2004.

(snip)

> Our results suggest
> that the stroma is a crucial target of the carcinogen and that 
> mutation in the Ha-ras-1 gene is neither necessary nor sufficient for
> tumor initiation.
 
> I am not predicting (although I am not excluding) that this will start
> a chain reaction of experiments designed to prove the EPIGENETIC
> origin of cancer, but it should make us rethink what is real
> (production of proteins) and what is fictious (determination of
> morphology, etiology of diseases, etc.) on the role of genes in
> biology. 

W.M.
The article, as I read it, has nothing to do with epigenetic origins of 
cancer.It simply says that the changes leading to the cancer occur in 
stromal cells rather than epithelial cells. 

N.C.
In my opinion, essential in this article is the fact that 
CANCEROUS EPITHELIAL CELLS ARE GENETICALLY
NORMAL.Those cells remain normal and do not  transform into cancer cells 
after exposure to the carcinogen.They transform into malignant cells
only when transplanted to the stroma previously exposed to the chemical 
carcinogen, what might indicate that the cells become malignant as a result of 
nongenetic changes in the stroma noncellular microenvironment (matrix)
surroundng the transplanted epithelial cells. Since the mutation believed to
induce cancer was found in both normal and cancerous cells according to
investigators it "did not correlate with initiation of neoplasia" and that 
the mutation "is neither necessary nor sufficient for tumor initiation."

However, you might argue that being nongenetic (no changes in the DNA of
malignant cells) by origin does not automatically  implies that the cause is
epigenetic.But, since the cause  is somewhere in the stroma altered
microenvironment and it is nongenetic, whether we would call it epigenetic or
supragenetic, etc. it makes no difference and depends on the definition of the
term. Most of us, if not all, would consider epigenetic any heritable change
that is not related to a change in DNA. Being this the case with mammary gland
cancer in rats, we might safely speak of its nongenetic origin, if
"epigenetic"
is not  preferred as a term.

Thank you.
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 3/16/04 9:00:18 PM