We can now see the genetic triggers of gasoline and cancer

Cancer genetic blueprint
revealed
Scientists have decoded the complete DNA
of a cancer patient and traced her disease
to its genetic roots.
The Washington University team identified 10
gene mutations which appeared key to the
development of the woman’s acute myeloid
leukaemia.
Just two of these had been linked to the
disease before.
The sequencing technique, described in the journal Nature, could be applied to
other cancers and aid the design of targeted drugs.
The researchers took two samples from the
woman in her 50s – who later died from the
disease – and examined the DNA for
differences.
One sample was taken from healthy skin cells,
the other from bone marrow tissue made up of cancerous cells.
They found that virtually every cell in the tumour sample had nine of the key
mutations.
Like most cancers, acute myeloid leukaemia (AML) – a cancer of blood-forming
cells in the bone marrow – arises from mutations that accumulate in people’s
DNA over the course of their lives.
However, little is known about the precise nature of those changes and how they
disrupt biological pathways to cause the uncontrolled cell growth that is the
hallmark of cancer.
Previous efforts to decode individual human genomes have looked at common
points of DNA variation that may be relevant for disease risk.
In contrast the Washington team, using a gene sequencing technique, were able
to sift through the three billion pairs of chemical bases that make up the human
genome to pull out the mutations that contributed to the patient’s cancer.
True landmark
Geneticist Dr Francis Collins, a former director of the US National Human
Genome Research Institute, called the study a “true landmark in cancer
research”.
Leukaemia targets cells in bone marrow
which form blood
This achievement ushers in a
new era of comprehensive
understanding of the
fundamental nature of cancer
Dr Francis Collins
Geneticist
He said: “In the past, cancer researchers have
been ‘looking under the lamp-post’ to find the
causes of malignancy – but now the team from
Washington University has lit up the whole
street.
“This achievement ushers in a new era of comprehensive understanding of the
fundamental nature of cancer, and offers great promise for the development of
powerful new approaches to diagnosis, prevention and treatment.”
Three of the newly-discovered mutations were in genes that normally suppress
tumour growth, and four were in genes linked to the spread of cancer.
The other appears to affect the transport of drugs into the cells, possibly fuelling
resistance to cancer therapy.
The researchers are still looking for other gene mutations which may also play a
part.
They also examined tumour samples from another 187 AML patients, but found
none had any of the eight new mutations.
Lead researcher Dr Richard Wilson said: “This suggests that there is a
tremendous amount of genetic diversity in cancer, even in this one disease.
“There are probably many, many ways to mutate a small number of genes to get
the same result, and we’re only looking at the tip of the iceberg in terms of
identifying the combinations of genetic mutations that can lead to AML.”
The researchers suspect that the mutations occurred one after another, with
each pushing the cell closer to malignancy.
Kat Arney, of the charity Cancer Research UK, said: “This is a very important
piece of research, not only for our understanding of leukaemia but for many
other types of cancer.
“Thanks to advances in technology it is now possible to unlock the genetic
secrets within cancer cells, which will be the key to better diagnostic tools and
treatments in the future.”
Ken Campbell, of Leukaemia Research said: “Although it is very early days, it is
realistic to think that these findings could lead to new treatments.
“Its wider application to other cancers may be limited though – the technique is
particularly valuable for blood cancers in which the chromosome changes are
usually simpler than in solid tumours at the time of diagnosis.”
This is a very important piece of
research, not only for our
understanding of leukaemia but
for many other types of cancer
Kat Arney
Cancer Research UK

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