THEY have finally caught the nasty genes
- which have been plaguing women
with breast cancer -- red-handed.
Breast cancer research took three significant strides this year with the isolation
of the BRCA-2 gene, with scientists
zeroing in on the relationship between
cancer gene mutation and the type of
cancer it causes and finally by the
isolation of the gene responsible for the
early onset of cancer.
The isolation of BRCA-2 by a team of
researchers at the Institute of Cancer
Research, London, is being seen as a
path-breaking find in breast cancer
research. Last year, when scientists had
isolated BRCA-1, they immediately suspected the involvement of another troublemaker. Now, the hunt is on for yet another, a third gene.
Researchers report that defects in
BRCA-1 account for almost half of the
known breast cancer cases in Britain,
while defects in BRCA-2 account for
another third. "There may be yet
another gene involved," say researchers.
Even though, "the lifetime risk of contracting breast cancer for someone with
abnormal BRCA-1 or BRCA-2 is about
80 per cent". Now that both genes have
been isolated, scientists will be able to
develop genetic tests to enable women
with a farnily history of breast cancer, to
find whether they are individually at risk.
On the other hand, pharmaceutical researchers have got
a vital clue about the molecular mechanism by which breast
cancer occurs. This will enable
them to design more effective
anti-cancer drugs, besides helping them to devise ways to
repair the defective gene
through gene therapy.
While the scientific community applauds the discovery
of BRCA-2, they have yet another
reason to celebrate. Simon
Gavther and his colleagues
at the Cancer Research
Campaigns, Human Genetics
group in Cambridge, have
worked out a relationship
between the position of BRCA- 1
mutations and the type of cancer they cause.
BRCA-1 is an example of a
gene that causes two diseases.
While the defective copies
Of 13RCA-1 account for roughly half
the inherited cases of breast cancer,
the gene can cause ovarian cancer
as well. Researchers say they can
now predict whether a woman will
develop both the diseases or just
breast cancer. It will depend on
determining the position of mutations
on the BRCA-1 gene.
It is reported that more than 100 different BRCA-1 mutations take place
along the length of the gene. Scientists
have discovered that mutations in the
third part of the cancer-causing genes
usually mean breast cancer alone. In families afflicted by both the types of
tumour, the mutations occur closer to
the first part of the gene.
While nobody knows which protein
the BRCA- I gene produces, or how the non-mutated form of this protein prevents cancer, scientists can take consolation from the discovery of a gene whose
overactivity is supposed to promote
The work conducted by a research
team headed by Patricia Steeg of the
National Cancer Institute in US, is significant. Scientists discovered that the
gene responsible for producing a protein called cyclin D, was "frequently
overactive in early breast cancers but
only rarely so in non-cancerous breast
Confirmation of this preliminary
discovery by further research, shall pave
the way for prevention of some breast
cancers. For instance, drugs to slow
down the activity of the gene will be useful for prevention of breast cancer in
certain high risk cases.
Larry Norton at the Memorial
Sloane Kettering Cancer Center in New
York rightly says, "it is just the beginning and we do not have a specific
therapy that is derived from this work".
But these discoveries undeniably open
up new vistas to arrest that lethal growth
in the breast.