Cloning brain tumour overrides malignant mutations.

Drugs that mimic cloning might one day help treat cancer Credit: © SPL

Scientists have grown mouse embryos from cloned brain tumours, they revealed yesterday. The remarkable results imply that drugs that mimic cloning might one day help to treat the pernicious cancer.

Tom Curran of St Jude Children's Research Hospital in Memphis, Tennessee, performed the technique that delivered Dolly on a brain-tumour cell. With his colleague James Morgan, he injected the mouse cell's cancerous DNA into a healthy egg that had been stripped of its own nucleus.

Despite carrying malignant genetic mutations, the cloned cell grew into a small mouse embryo. "No one predicted it," Curran told the Society for Neuroscience's annual meeting in Orlando, Florida. Only when an abnormal gene failed to drive embryo growth did the mouse die, he thinks.

Some of the genetic changes that turn a healthy cell into a cancerous one must be erased during cloning, explains Curran, a process called reprogramming. These changes probably involve reversible chemical markers or structural changes in DNA that control which genes are active, rather than being mistakes in the genetic code itself.

The discovery suggests that drugs that help to reprogramme cells, and imitate cloning, might also help beat brain tumours. Some such therapies, such as histone deacetylase inhibitors, are already being developed to treat other cancers.

Embryonic tumour

Even without cloning, brain tumours share many characteristics of a growing embryo, the Orlando meeting heard. "There are intriguing trends," says cancer researcher Luis Parada of the University of Texas Southwestern Medical Center in Dallas.

Parada revealed that adult stem cells that sprout nervous system neurofibromas switch on and off many of the same genes as embryonic precursors to nerve cells. And Curran's team found that gene activity in medulloblastomas in the brain's cerebellum mirrors that in the growing tissue.

“We'd all like to discover where the genes are and how they operate Terry Van Dyke , University of North Carolina”

Ultimately, scientists hope to work out the fatal sequence of events that converts a culprit stem cell into a budding cancer and find drugs that reverse or block it. Buried in the brain, such tumours remain the most insidious and mysterious of cancers; 100,000 are diagnosed annually in the United States alone, and most are incurable.

The recent creation of genetically modified mice with versions of the disease has fuelled the latest advances. Yesterday's special session at the annual neuroscience gathering was the first time cancer has been timetabled.

"We haven't come up with unified theories," says the creator of another tumour model, Terry Van Dyke of the University of North Carolina in Chapel Hill. "We'd all like to discover where the genes are and how they operate."

Authors Helen Pearson View author publications You can also search for this author in PubMed Google Scholar

Additional information University of North Carolina

Related links Related links Related external links Society for Neuroscience 2002 American Brain Tumor Association

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