People with the genetic condition neurofibromatosis type 1 (NF1) are prone to developing tumours on nervous system tissue. A new study from Washington University School of Medicine in St. Louis, USA, has found that the development and growth of such tumours are driven by nearby noncancerous neurons and immune cells. The findings point to potential new therapeutic targets for people with NF1.
Children with the genetic condition neurofibromatosis type 1 (NF1) can develop brain and nerve tumours. If a tumour develops within the optic nerve, which connects the eye and the brain, the child may lose his or her vision.
New research at Washington University School of Medicine in St. Louis indicates that the growth of these brain tumours is driven by nearby noncancerous neurons and immune cells, and that targeting immune cells slows tumour growth in mice. The findings, published May 1 in Nature Communications, point to new potential treatments for low-grade brain tumours in people with NF1.
“The fact that nerve cells and immune cells interact to support a tumour is a new way of thinking about how tumours develop and thrive,” said senior author David H. Gutmann, MD, PhD, the Donald O. Schnuck Family Professor of Neurology and director of the Washington University Neurofibromatosis Center. “These tumours are arising in the nervous system, but until recently, few people had considered that the nerve cells themselves could be playing a role in tumour development and growth. These findings show that we have to consider nerve cells as participants, if not essential drivers, of cancer development.”
NF1 affects about one in every 3,000 people. It is caused by any one of a variety of mutations in the NF1 gene. While people with NF1 usually come to medical attention for birthmarks on their skin, nearly one in five children with NF1 will develop a brain tumour on the optic nerve, called an optic glioma.
To better understand what drives the development and growth of these brain tumours in people with NF1, first author Xiaofan Guo, MD, a graduate student in Gutmann’s research laboratory, and colleagues studied mice with NF1 mutations and optic gliomas. The team previously had discovered that the tumour cells in optic gliomas are interspersed with immune cells that help drive tumour formation and growth. But there is also another cell type in the vicinity of the tumour: neurons.
Suspecting that neurons also might be contributing to tumour growth, the researchers examined human neurons with NF1 mutations that had been grown from stem cells. They discovered that the neurons release a protein that activates immune cells known as T cells, which then produce proteins that promote the growth of tumour cells. The findings jibe with data from people with low-grade gliomas. By analyzing two publicly available datasets, the researchers found that patients whose tumours had more of a kind of T cell known as CD8+ T cells had reduced overall survival.
Disrupting the communication between neurons, T cells and tumour cells potentially could slow the growth of tumours, the researchers said. In the new study, they removed T cells from mice with optic gliomas, or prevented T cells from getting into the brains of such mice. In both scenarios, the researchers found that the optic gliomas grew more slowly in the absence of T cells.
“What we have here is a new way of thinking about how neurons and immune cells interact to control tumour growth, adding important new insights to the emerging field of cancer neuroscience,” Gutmann said. “We are excited about harnessing these critical interactions to develop new therapeutic strategies for childhood brain tumours.”
Paper: Xiaofan Guo, Yuan Pan, Min Xiong, Shilpa Sanapala, Corina Anastasaki, Olivia Cobb, Sonika Dahiya, David H. Gutmann. Midkine activation of CD8 T cells establishes a neuron–immune–cancer axis responsible for low-grade glioma growth. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-15770-3