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[tvoivozhd <tvoivozd AT infionline.net>]

Bone marrow cancer (myelofibrosis) begins with a single DNA-damaged cell 
that across a year or so, displaces all the healthy bone-marrow cells.  
Watch the Stemline licensee for cure progress---assuming early detection 
of bone-marrow cancer takes place.

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   New tests identify cancer "ringleaders"

   * 12:59 20 January 2005
   * NewScientist.com news service
   * Andy Coghlan

Cancer treatments could improve by targeting cancer "stem cells" which 
give birth to all other cells in tumours, say researchers who have 
devised techniques for identifying and potentially killing two types of 
cancer stem cell.

Killing the stem cells is vital because these cells avoid destruction 
and trigger regrowth of cancer even when all other cancer cells have 
been obliterated through standard drug or radiation therapy.

By wiping out the stem cell "ringleaders" as well as the other cancer 
cells, doctors stand a much better chance of eradicating the cancer in a 
patient for good.

Now, new techniques to do this developed at the University of Cambridge, 
UK, and Kumamoto University, Japan, have been licensed for 
commercialisation to Stemline, a biotechnology company in New York, US.

"Once we have eradicated the cancer stem cells, in essence we have 
destroyed the engine responsible for treatment failure and disease 
recurrence, the major problems for fighting cancer," says Ivan 
Bergstein, chief executive of Stemline.

But it could be five years before the first treatments start to come 
through, warns Toru Kondo, head of the team at the University of 
Cambridge which pioneered the two new tests.


         Dye pump

The first test relies on antibodies which recognise and bind to CD133, a 
surface protein unusually common on stem cells and already known to 
orchestrate several human cancers, including those of the blood, 
prostate and nervous system.

The second test relies on a blue dye absorbed without trace by ordinary 
cancer cells but pumped out again by stem cells found in certain 
cancers, such those of the breast and aggressive glioma cancers found in 
the brain. They can do this because, unlike the ordinary cells, they 
have a transporter protein, ABCG2, which pumps the dye out through the 
cell membrane.

"If you use this special dye to label cells, the cancer stem cells 
exclude it," Kondo explains.

Stemline is using the tests to find out which cancers depend on which 
stem cells, and to identify drugs which kill the cancer stem cells but 
spare healthy stem cells.

One possibility, says Kondo, is to target the cancer stem cells with 
specially generated antibodies loaded with toxins or radioactive 
elements lethal to the stem cells.


         Telltale markers

But it might first be necessary to identify further telltale markers of 
the cancer stem cells to make doubly sure that the cancer stem cells 
alone are killed, says Peter Dirks of the Hospital for Sick Children in 
Toronto, Canada.

Dirks led a team which demonstrated 
<http://www.newscientist.com/article.ns?id=mg18424741.700> in 2004 that 
brain cancers transplanted into mice only grew if the transplanted 
tissue included stem cells bearing the surface marker, CD133.

But Dirks warns that some healthy stem cells carry CD133 or ABCG2 on 
their surfaces too, and so could be accidentally destroyed by drugs 
targeting the cancer stem cells.

"Hopefully, the investigators can find new markers that could be unique 
to cancer stem cells, enabling safer targeting," says Dirks. Indeed, 
Stemline is currently seeking additional markers through collaborations 
with academic institutes in the US.


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     <http://www.newscientist.com/article.ns?id=mg18424741.700>
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     <http://www.newscientist.com/article.ns?id=dn6511>
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