New gene involved in breast,
prostate and other cancers
BETHESDA, MD -- Apr.
1, 2001 (Cancer Digest) -- A new tumor suppressor gene, that
appears to be involved in a wide range of cancers, has been isolated
say scientists at the National Human Genome Research Institute
(NHGRI) in Washington, D.C. and the M.D. Anderson Cancer Center
Houston, Tex.
While finding a new
gene alone is not surprising, the discovery of this gene demonstrates
the value of the first draft sequence of the entire human genome
to molecular genetics research, says Dr. Francis S. Collins,
NHGRI director.
"This finding
is an excellent example of how individual researchers, aided
by the availability of the near-complete sequence of the human
genome can make major advances in our knowledge of the genetic
basis of disease in a matter of a few years or less," said
Collins in an announcement.
In the past, the discovery
of a new tumor suppressor gene would require a major effort involving
many scientists, often in several laboratories, working for several
years.
The research team including
co-authors Dr. Jean Claude Zenklusen of M.D. Anderson and Dr.
Eric Green of the NHGRI published its findings in the April issue
of Nature Genetics. They identified the gene as ST7, short for
Suppression of Tumorigenicity 7, on chromosome 7.
"Inactivating
a tumor suppressor gene is like disabling the brakes on a car,"
said Green in a prepared statement. "Without the function
of such a gene, a tumor keeps growing out of control. And just
like a car without brakes, the consequences can be fatal."
The study shows that
ST7 is widely expressed in normal tissues throughout the body
and that the gene is often disrupted by mutation or deletion
in tumors arising from epithelial cells, such as cancers of the
breast, prostate, colon and ovary.
Tumor suppressor genes
play a key role in the regulation of cell growth. Scientists
have known for about 15 years that when a tumor suppressor gene
is inactivated, the cells it affects grow out of control and
become cancerous. Scientists know of at least 30 tumor suppressor
genes and a search of gene databases suggests that there may
be another 100 or more.
Preliminary evidence
suggests that ST7 may be involved in regulating the growth of
blood vessels into a tumor, a process called angiogenesis.
"If ST7 is involved
in regulating angiogenesis, it may prove to be a target for developing
drugs that would interfere with that process," Zenklusen
says. "Without an adequate blood supply, a tumor withers
away and dies. So theoretically, if you could prevent angiogenesis,
you might be able to come up with a way to kill the tumor without
harming the patient."
The researchers still
don't know exactly what the gene does. "ST7 has no relatives
or structural similarities to any other known gene," Zenklusen
says. But the scientists have shown that the gene has been highly
conserved over evolution, because it is widely found in lower
organisms. That generally means the gene plays an important function
in the body.
SOURCE: April 2001, Nature Genetics (Vol. 27, No. 4).
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