School of Medicine

Brain tumors caused by normal neuron activity in mice predisposed to such tumors

Researchers at Washington University School of Medicine in St. Louis and Stanford University School of Medicine have found that normal exposure to light can drive the formation and growth of optic nerve tumors in mice — and maybe people — with a genetic predisposition. Such tumors can lead to vision loss. (Photo: Getty Images)

Seeing, hearing, thinking, daydreaming — doing anything at all, in fact — activates neurons in the brain. But for people predisposed to developing brain tumors, the ordinary buzzing of their brains could be a problem. A study by researchers at Washington University School of Medicine in St. Louis and Stanford University School of Medicine shows that the normal day-to-day activity of neurons can drive the formation and growth of brain tumors.

The researchers studied mice genetically prone to developing tumors of their optic nerves, the bundle of neurons that carries visual signals from the eyes to the brain. The mice served as a model for children with the genetic condition neurofibromatosis type 1 (NF1). About one in six children with NF1 develops low-grade optic nerve tumors by age 7. In this study, mice with Nf1 mutations raised under normal lighting developed tumors; those kept in the dark during a critical period of development did not.

The findings, published May 26 in the journal Nature, suggest that neuronal activity plays an underappreciated role in nervous system cancers. The research opens up new avenues to preventing brain tumors in children at high risk for them.

“Optic gliomas are very common in children with NF1, and they can cause vision loss,” said co-senior author David H. Gutmann, MD, PhD, the Donald O. Schnuck Family Professor of Neurology at Washington University and the director of the university’s NF Center. “We don’t have a good way to predict who will develop tumors or any way to prevent them. But now that we know these brain tumors are caused by exposure to light and neuronal activity, we can start thinking of next-gen prevention strategies. Maybe we can give kids cool sunglasses to wear with filters or lenses to block out certain wavelengths of light, or repurpose drugs that suppress excessive neuronal activity, and protect these kids from developing brain tumors and losing their sight.”

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