Monday, December 13, 2010

Leukemia Researchers 'Switch off Faulty Stem Cells'

Leukemia research has taken a "critical step forward", say British scientists, after they managed to turn off faulty stem cells that trigger the disease.

By suppressing a protein in the blood, the team at King's College London transformed leukemic stem cells back into ordinary ones without cancerous features.

They also managed to "re-sensitize" the most aggressive leukemic stem cells, which had become resistant to treatment, so they responded to anti-cancer drugs.

Professor Eric So, who led the team, said: "These results are extremely exciting and represent a critical step forward in the search for more effective treatments for this devastating form of leukemia.

"The findings provide compelling evidence that this protein could be exploited to develop an effective therapeutic target for this form of the disease."

The study, reported in the journal Cancer Cell, involved a dangerous strain of leukemia driven by defects in the mixed lineage leukemia (MLL) gene.

Stem cells are immature cells that can develop into a number of different mature cells.

People with MLL have leukemic stem cells which are part-way along the path to being cancerous white blood cells, although not all of them reach this stage.

The researchers showed in mice how "normal" stem cells could become leukemic stem cells and induce cancer.

They discovered that the process involved activation of a blood protein called beta-catenin. Suppressing this protein delayed the onset of cancer, slowed down cancer growth, and reversed leukemic stem cells to a pre-cancerous stage.

When beta-catenin was completely inactivated in mice with pre-leukemic cells, the animals did not develop cancer despite carrying all the necessary MLL mutations.

Laboratory studies on leukemic cells from human patients again showed that suppressing beta-catenin lessened their ability to multiply and renew themselves.

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