New cancer drug?

Washington - Her carefully cultured cells were dead and Katherine Schaefer was annoyed, but just a few minutes later, the researcher realised she had stumbled onto a potential new cancer treatment.

Schaefer and colleagues at the University of Rochester Medical Centre in New York believe they have discovered a new way to attack tumours that have learned how to evade existing drugs.

Tests in mice suggest the compound helps break down the cell walls of tumours, almost like destroying a tumour 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, oesophageal cancer, liver and skin cancers.

"I was using these cancer cells as models of the normal intestine," Schaefer said.

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 diarrhoea.

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.

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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 tumour 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."

So...will the pharmaceutical companies let this drug exist? Or will they shut it down because it threatens their cancer medicines?