Oncogenic mutations?

Ola Myklebost olam at radium.uio.no
Mon Apr 26 03:38:43 EST 1993


In article <6849 at krafla.rhi.hi.is>, agnar at rhi.hi.is (Agnar Sturla Helgason)
wrote:
> 

. According to the 2nd edition of The Cell 
> (Alberts & co.) oncogenic mutations are always dominant, while tumor 
> suppressor gene (anti-oncogenic) mutations are always reccesive. Another 
> reference seems to indicate the possibility of recessive oncogenic mutations 
> (this could be a misunderstanding on my behalf). 
> Can an oncogenic mutation be reccesive? And if not, why?
> 

Oncogenes were classically identified by transfection, and thus were
dominant (over the endogeneous genes). However, many transfection
experiments overexpress the exogeneous gene vastely, and the genes may not
always be dominant at physiological levels. (or levels obsevred in tumors).


When it comes to supressor genes always being recessive, the same applies:
p53 was originally called an oncogene because when the mutated gene was
transfected
it transformed cells. However, this was because overexpression of the
mutant competed with the wt genes. Because p53 tetra-merises, certain
lack-of-function mutations can enable the mutant to (partly) inactivate the
wt gene.

I can not help you with a newer definition covering all this...


Ola Myklebost             Email olam at radium.uio.no
Dept of Tumor Biology
Inst for Cancer Research
The Norwegian Radium Hospital
N-0310 OSLO, Norway
Tel +47-22-50-60-50, xtn 9830, Fax +47-22-52-24-21



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