Cancer-Causing Protein May Restore Spinal Cord, Brain Cells

Scientists have discovered that a protein known for triggering the growth of cancer also plays an unexpected role in restoring the ability of neurons to regenerate, making it a significant target for tackling spinal cord damage or neurologic disorders such as diseases like Alzheimer's disease.

The study was published in the journal Nature's website on June 28, 2006, and will be published in an upcoming issue. "Our finding suggests that the same process this protein uses for proliferating cancer could also potentially be used to regenerate axons that are damaged in spinal cord injuries or neurological diseases,” said Antonio Iavarone, M.D., associate professor of neurology and pathology at Columbia University Medical Center's (New York, NY, USA) Institute for Cancer Genetics, and the study's lead author. The proteins, called Id (idiotype) proteins, are plentiful in the cells of many different types of cancer, including brain, breast, and pediatric tumors, and were known to promote tumor growth and contribute to the spread of cancer.

While looking for ways to attack Id's cancer-causing properties, Dr. Iavarone and Anna Lasorella, M.D., assistant professor of pediatrics and pathology at the Institute for Cancer Genetics, found the surprising neuron-healing properties of Id proteins. Their early results, also published in the Nature study, are important for potential cancer therapies. The researchers found that an enzyme inside normal cells, called adenomatous polyposis coli (APC), typically degrades Id proteins soon after they are produced, but cancerous cells demonstrate a very high level of Id proteins. This suggests that re-introducing the APC enzyme into cancer cells could eliminate the proteins and arrest the growth of tumor cells, something that researchers will now further examine.

Among neurons, however, the researchers assessed the Id protein potential for promoting growth, instead of suppressing it. The researchers wanted to use the power of Id proteins to stimulate growth of axons--the structures on neurons responsible for transmitting electrical signals in the brain and spinal cord. However, to do that they needed to solve the problem of the APC enzyme, which degrades the protein in healthy cells. So they devised a "super” Id protein that would resist degradation from the APC enzyme, allowing it to promote axonal growth.

Usually, neurons cannot regenerate damaged axons because of the presence of myelin, a substance that surrounds the axons, but the degradation-resistant "super” Id protein was able to promote axon growth even in the presence of myelin. Dr. Iavarone also noted that there is no possibility that such a therapy would cause cancer in the brain or spinal cord. "Neurons have completely lost the ability to create new cells so there's no danger of creating a tumor. The only growth they're capable of is regeneration of their axons,” he said.



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