Reducing Light Exposure and Neuronal Activity Decreases Risk of Optic Glioma, in Mice

Article: Brain tumors caused by normal neuron activity in mice predisposed to such tumors
Source: Washington University School of Medicine at St. Louis, via NEI
Published: May 26, 2021

Increased activity of the optic nerve drives growth of Nf1-OPG

Seeing, hearing, thinking all require brain activity. But for those at risk, the normal day-to-day activity of neurons can drive the formation and growth of brain tumors, such as optic gliomas in this case. Since the neurons of the optic nerve become active when exposed to light, the researchers wanted to investigate whether reducing exposure to light could decrease neuronal activity and thereby limit tumor formation. Using a mouse model of neurofibromatosis type 1 (NF1), they found that mice with Nf1 mutations raised under normal lighting developed tumors, while those kept in the dark during a critical period of development did not. Additional experiments narrowed down the critical window to age 6 to 12 weeks in these mice. None of the mice reared in the dark during that time frame developed tumors by 24 weeks of age. Limited effect was seen beyond the critical window; when the tumors have already formed, placing the mice into darkness slowed tumor growth but did not shrink them. In both mice with Nf1 mutations and in tissue samples of people with low-grade brain tumors, tumor formation was associated with abnormally high levels of a protein called neuroligin 3. In mouse studies, blocking the protein with a drug or eliminating the protein through genetic modification resulted in fewer and smaller tumors. Understanding risk factors for tumor formation can help guide preventative strategies. As one of the senior authors states, “[N]ow 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.”

My rating of this study: ⭐⭐

Pan Y, Hysinger JD, Barron T, et al. "NF1 mutation drives neuronal activity-dependent initiation of optic glioma." Nature.  594:277–282. 26 May 2021. https://doi.org/10.1038/s41586-021-03580-6