Weed treats deadly child cancer

A chemical isolated from a weed may provide a new way to treat the most common form of aggressive brain cancer in children.

Medulloblastoma accounts for about a fifth of all childhood brain tumours and can spread from the brain to other parts of the body. There is currently no effective treatment.

Researchers have found that they were able to kill off cultured mouse medulloblastoma cells and tumours, and similar cells taken from human tumours.

The key was a chemical called cylcopamine, which was extracted from the corn lily, a plant that grows in mountain meadows in the western US.

Cylcopamine was able to block growth signals put out by a protein called Hedgehog.

Crucial role

These signals play a crucial role in directing the development of tissues during an embryo's growth.

But if they are activated at a later stage they can lead to the formation of cancer, particularly in an area of the brain called the cerebellum.

Cyclopamine reduced growth of mouse medulloblastoma cells grown in the laboratory and encouraged tumours implanted in mice to shrink.

The chemical also killed 99.9% of cancer cells taken from seven patients who had undergone surgery to remove medulloblastomas.

The researchers from Johns Hopkins University in Baltimore and the Fred Hutchinson Cancer Research Center in Seattle, said the research was promising.

But they warned there was still a long way to go before a new treatment would be widely available.

But researcher Dr James Olson said: "Success in the mice was not unexpected because we designed the mouse's tumours to rely on the Hedgehog signal.

"But learning that medulloblastoma samples from all seven patients were very sensitive to cyclopamine as well was very surprising indeed."

Other possibilities

Other cancers are also linked to Hedgehog signalling, including rhabdomyosarcoma, a childhood muscle cancer, and basal cell skin cancer, the most common cancer in adults.

However, the effect of blocking Hedgehog on the growth of these cancers has not been evaluated.

The researchers, whose work is published in the journal Science, believe other chemicals will also be found to achieve the same effect.

Tom Lober, of Cancer Research UK, told BBC News Online: "Cyclopamine or similar molecules could become important tools for treating medulloblastoma in the future.

"The research is still in its very early days and it will be years before researchers will be able to confirm its usefulness for patients.