For decades, scientists thought they knew what a deadly form of brain tumour needed to grow: sugar.
But now researchers have found that a trick used to culture tissues in the lab had actually been fooling them and what glioma cancer cells actually require is fat.
The discovery has led to an entirely new approach to treating the disease, which could ultimately result in drugs that are able to significantly extend the life of patients.
Gliomas, such as astrocytoma or ependymoma, are among the hardest cancers to treat with 60 per cent of sufferers dying within a year.
Dr Elizabeth Stoll, who led the research team, said most cells in the brain use sugar as their main source of energy.
It had been thought that the brain cancer cells were no different and tests of tissue samples in the lab appeared to confirm this.
But Dr Stoll, who stressed that their findings were at the cell level and did not have any dietary implications, said they had shown that the tumours actually rely to a large extent on fat.
When tissue samples and live tumours in mice were treated with a drug, called etomoxir, designed to prevent the cells from using fat, it slowed the cancer’s growth, the researchers reported in the journal, Neuro-Oncology.
“We tested etomoxir in our animal model, and showed that systemic doses of this drug slow glioma growth, prolonging median survival time by 17 per cent,” said Dr Stoll, of Newcastle University’s Institute of Neuroscience.
“These results provide a novel drug target which could aid in the clinical treatment of this disease for patients in the future.”
She told The Independent that she had been surprised that the glioma cells did not simply switch to using sugars when they were unable to use fat.
“One way they do switch is if they are exposed to blood serum. Then they switch quite easily,” she said.
And this was the source of the misunderstanding about brain cancer cells because of the way researchers in a lab would treat tissue samples.
“What we have always needed to do is put the cells in [blood] serum. It’s a trick to get the cells to grow in culture,” Dr Stoll said.
“If you take malignant brain tumours and expose them to blood serum, it changes them.
“For 60 years, we have believed all tumours rely on sugars for their energy source and the brain relies on sugars for its energy source, so you certainly would think brain tumours would.”
She said it was possible that different cancers would use different sources of energy in the same way that different parts of the body do.
For example, the fast-twitch muscles that help people to sprint use sugars, while slow-twitch muscles used during endurance exercise burn fat.
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