Three individual studies have been able to unearth a shocking discovery about tumour cells – they can attach themselves, and feed off, the neurons in the brain. This revelation might be another clue in understanding the labyrinth of tumours, and consequently allowing researchers to look at this puzzle from another perspective.
Brain cancers called gliomas, along with some breast cancers that spread to the brain possess this astonishing ability. The findings bolster a growing realisation among doctors and scientists that the nervous system plays an important role in the growth of cancers, says Michelle Monje, a pediatric neuro-oncologist at Stanford University in California and lead author of one of the studies.
This finding still came as a surprise. “It’s unsettling,” Monje says. “We don’t think of cancer as forming an electrically active tissue like the brain.”
Frank Winkler, a neurologist at Heidelberg University in Germany, uncovered the phenomenon while studying how cells in some brain tumours communicated: through synapses (structures that neurons use to communicate with one another).
Initially, the synapses were forgone as a random occurrence, but later studies proved this assumption wrong. They found synapses in glioma samples taken from cancer cells grown in culture, human glioma tumours transplanted into mice and glioma samples taken from ten people.
Monje’s team simultaneously discovered synapses between neurons and cells in paediatric gliomas. The parallel research proved that tumour synapses helped cancer cells flourish. Monje’s findings explain why tumours are notoriously difficult to treat – they tend to weave through the brain instead of staying in one place.
This phenomenon isn’t limited to brain tumours though. The third paper, published by Douglas Hanahan, a cancer scientist at the Swiss Institute for Experimental Cancer Research in Lausanne, and his team describes breast-cancer cells in the brain that act like neurons. These breast cancers are known for spreading to the brain and, once there, they are almost impossible to treat. Hanahan’s team showed that when breast-cancer cells invade the brain, they form a specialized type of synapse that allows them to soak up a chemical called glutamate. This is the most abundant neurotransmitter in the brain and can also boost tumour growth.
All three studies underscore the resilience of cancer cells, says Lisa Sevenich, who studies brain cancer at the University of Frankfurt in Germany. Researchers hope that these findings will lead to new ways of treating cancer.