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Scientists
Watch Breast
Cancer
Gene At Work
NEW
YORK (Reuters Health) - Shedding new light on gene-related cases
of breast and ovarian cancer, scientists have discovered that
a gene linked to both diseases may play a crucial role in repairing
genetic damage in body cells.
Researchers
have known for several years that mutations in the genes BRCA1
and BRCA2 increase awoman's risk of breast and ovarian cancer.
The new research, reported in the May 22nd issue of Proceedings
of the National Academy of Sciences, offers clues as to why.
BRCA1 appears
to spot and help mend DNA damage that occurs during normal cell
division. The implication is that when BRCA1 is mutated, the DNA
repair process may eventually go wrong, allowing abnormal cells
to proliferate and cancer to begin.
Dr. Tanya
T. Paull and her colleagues were able to observe BRCA1's interaction
with DNA by genetically engineering human BRCA1 protein and observing
it in a test tube. Just creating the protein in the lab has been
a significant obstacle for scientists, according to Paull, a researcher
at the University of Texas,Austin.
But, she said
in an interview with Reuters Health, her team was able to show
for the first time that BRCA1 binds directly to cell DNA. Moreover,
Paull explained, the gene ``prefers'' to bind to ``unusual'' DNA
structures. This strongly suggests BRCA1 is a key player in the
DNA repair system, the body's first line of defense against cancer.
Women found
to be carriers of a BRCA1 or BRCA2 mutation have one defective
copy of the gene and one normal copy. They are more susceptible
to cancer, Paull noted, because if something goes wrong with the
normal copy, there is nothing left to take over the gene's job.
But why BRCA
mutations are linked only to breast and ovarian cancers is a mystery.
If BRCA1 is so important to DNA repair, Paull said, ``you'd expect
the effects of a mutation to be across the body.''
One theory
is that something inherent in breast and ovary cells makes them
more susceptible to the loss of a functioning BRCA gene. For example,
Paull explained, during puberty breast cells go through a period
of rapid division, which could increase the rate of DNA damage
within the cells.
While this
research is for now ``far removed'' from women who carry BRCA
mutations or who have cancer, Paull stressed the importance of
understanding what happens at the most basic cellular level during
cancer development.
``I think
the only way to find cures,'' she said,'' is to understand what's
going wrong in the cells.''
SOURCE:
Proceedings of the National Academy ofSciences 2001;98:6086-6091.
Reference
Source 89
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