Faulty liver 'stem cells' might cause 40 per cent of liver cancers
WEDNESDAY 13 FEBRUARY 2008
US scientists have discovered stem cells in the liver, and found that
they might be responsible for 40 per cent of liver cancers when they
malfunction.
Scientists have spent a number of years looking for stem cells in the
liver, but the latest study in the Proceedings of the National
Academy of Sciences represents the first time that these have been
found in the organ.
The breakthrough came when Lynt Johnson, a transplant surgeon at
Georgetown University Medical Centre, suggested that Dr Lopa Mishra's
research team look for stem cells in donor liver tissue that had
recently been transplanted into patients with liver failure.
He argued that stem cells would be particularly active in this tissue
as they would be rapidly generating new liver cells.
Acting on his suggestion, the researchers took liver biopsies from
six surgery patients within four months of transplantation, and
looked for cells producing certain proteins characteristic of stem
cells.
For the first time, they were able to find normal stem cells in the
tissue, at a rate of two to four stem cells per 30,000 to 50,000
cells.
Dr Mishra, lead author and director of cancer genetics at
Georgetown's department of surgery, said: "These cells were working
really hard, expressing all of these proteins in abundance. In our
staining tests they looked like stars, surrounded by shells of cells
that were also expressing TGF-beta (transforming growth factor beta)
in order to make new liver cells."
The researchers then used the same technique to find cancer stem
cells in tissue from ten liver cancer patients, and found that one of
the apparently characteristic proteins, TGF-beta, was missing.
Dr Mishra revealed: "We found that all of these stem cells had lost
TGF-beta. Without the brakes that TGF-beta puts on cancer, the stem
cells had turned into bad guys."
The researchers also found evidence that a new experimental drug that
shuts down stat3 - another protein associated with stem cells - may
be effective against primary liver cancer, which accounts for around
one per cent of newly-diagnosed cancers in the UK.
Preliminary results of the drug's effect on liver cancer cells from
both mice and humans suggest that it dramatically inhibits cancer
cells and the researchers are now trialling the drug on mice with
liver cancer that are lacking TGF-beta.
Dr Mishra confirmed: "After locating the cancer stem cells that help
control development of these tumours, we were able to find a
potential vulnerability that might form the basis of a new treatment
for this disease - which is greatly needed."
She concluded: "Now we have a way to think about treating liver
cancer, and this is very exciting. Besides stat3, there are other
proteins that are activated on cancer stem cells, so they might also
offer us additional drug targets."
News provided by Adfero in collaboration with Cancer Research UK.
Please note that all copy is © Adfero Ltd and does not reflect the
views or opinions of Cancer Research UK unless explicitly stated.
http://info.
y/18465419
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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