by Playfuls Staff |
4th February 2007
Her carefully cultured cells were
dead and Katherine Schaefer was annoyed, but just a few minutes
later, the researcher realized she had stumbled onto a
potential new cancer treatment. [more]
Schaefer and colleagues at the University of Rochester
Medical Center in New York believe they have discovered a new
way to attack tumors that have learned how to evade existing
drugs.
Tests in mice suggest the compound helps break down the
cell walls of tumors, almost like destroying a tumor cell's
"skeleton."
The researchers will test the new compound for safety and
hope they can develop it to treat cancers such as colon cancer,
esophageal cancer, liver and skin cancers.
"I was using these cancer cells as models of the normal
intestine," Schaefer said in a telephone interview.
Normal human cells are difficult to grow and study in the
lab, because they tend to die. But cancer cells live much
longer and are harder to kill, so scientists often use them.
Schaefer was looking for drugs to treat the inflammation
seen in Crohn's disease and ulcerative colitis, both of which
cause pain and diarrhea.
She was testing a compound called a PPAR-gamma modulator.
It would never normally have been thought of as a cancer drug,
or in fact a drug of any kind.
"I made a calculation error and used a lot more than I
should have. And my cells died," Schaefer said.
A colleague overheard her complaining. "The co-author on my
paper said,' Did I hear you say you killed some cancer?' I said
'Oh', and took a closer look."
They ran several tests and found the compound killed
"pretty much every epithelial tumor cell lines we have seen,"
Schaefer said. Epithelial cells line organs such as the colon,
and also make up skin.
It also killed colon tumors in mice without making the mice
sick, they reported in the journal International Cancer
Research.
The compound works in much the same way as the taxane
drugs, including Taxol, which were originally derived from
Pacific yew trees.
"It targets part of the cell cytoskeleton called tubulin,"
Schaefer said. Tubulin is used to build microtubules, which in
turn make up the cell's structure.
Destroying it kills the cell, but cancer cells eventually
evolve mechanisms to pump out the drugs that do this, a problem
called resistance.
"Resistance to anti-tubulin therapies is a huge problem in
many cancers. We see this as another way to get to the
tubulin," Schaefer said.
The PPAR-gamma compound does this in a different way from
the taxanes, which might mean it could overcome the resistance
that tumor cells often develop to chemotherapy.
"Most of the drugs like Taxol affect the ability of tubulin
to forms into microtubules. This doesn't do that -- it causes
the tubulin itself to disappear. We do not know why."
Schaefer's team plans more safety tests in mice. As the
compound is already patented, her team will probably have to
design something slightly different to be able to patent it as
a new drug.
Taxol, developed by U.S. National Cancer Institute
researchers and manufactured by Bristol-Myers Squibb in 1993,
had annual sales of $1.6 billion at its peak in 2000.
By Maggie Fox, Health and Science Editor(c) Reuters 2007. All rights reserved. Republication or redistribution of Reuters content, including by caching, framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
