A new study has discovered evidence that brain tumors utilize fat as their preferred source of energy, bringing into question the decades-long assumption that sugar is their primary fuel source.
If validated, this could essentially change the way we deal with cancer in the future, considering that in recent times scientists have been focusing their efforts on ways to starve cancer cells of their sugar supply.
“For 60 years, we have believed all tumors rely on sugars for their energy source, and the brain relies on sugars for its energy source, so you certainly would think brain tumors would,” lead researcher Elizabeth Stoll, a neuroscientist from Newcastle University in the UK, told Ian Johnston at The Independent.
A glioma is a kind of brain tumor that grows from glial cells – cells that support the nerve cells and assist to maintain the blood-brain barrier. Glial cells comprise 90 percent of the brain’s overall cells, and up until recently have actually been shrouded in mystery.
There are three types of glial tumors – astrocytoma, oligodendroglioma, and glioblastoma – and they can be notoriously difficult to treat. Glioblastomas are the most typical and most aggressive form, with just 30 percent of patients in the US living to more than 2 years after medical diagnosis.
A new target for treatments might make a huge difference, with Stoll and her team discovering that when they prevented the tumor cell’s ability to process fat as fuel, their growth rate slowed considerably, which relates to a much better survival rate.
The team dealt with human tumour tissue that had been donated by glioma patients undergoing surgery, and live mouse models of the illness, and treated them with a fat oxidation inhibitor called etomoxir.
“We tested etomoxir in our animal model, and showed that systemic doses of this drug slow glioma growth, prolonging median survival time by 17 percent,”Stoll said in a press statement. “These results provide a novel drug target which could aid in the clinical treatment of this disease for patients in the future.”
The concept of cancer development being sustained by glucose – a simple sugar that healthy cells likewise break down to utilize as an energy source – has actually been around since at least the 1950s, when Nobel Prize-winning German scientist Otto Warburg observed that tumors mostly metabolised glucose in order to grow.
This process, called the Warburg result, and is now approximated to happen in approximately 80 percent of cancers.
“It is so fundamental to most cancers that a positron emission tomography (PET) scan, which has emerged as an important tool in the staging and diagnosis of cancer, works simply by revealing the places in the body where cells are consuming extra glucose,” Sam Apple reports for The New York Times.
With a lot of cancers appearing to respond first on glucose and then for their growth, also healthy brain cells themselves likewise depending on sugar to keep functioning, it was only natural for researchers to presume that cancer cells in the brain would follow suit.
This perception was also perpetuated by the way researchers treat tissue samples in the lab.
As Stoll described to The Independent, it’s common for scientists to draw out brain tumor cells from patients and put them into blood to culture them in the laboratory. However the basic act of putting these cells into a medium where sugar is more abundant than fat appears to alter them, prompting them to change fuel sources and use sugar because they’re starved of fat.
Stoll’s team avoided this complication by culturing their mouse and human tumor cells in serum-free conditions.
“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,” she said. “If you take malignant brain tumors and expose them to blood serum, it changes them. Then they switch quite easily.”
We ought to make it clear that Stoll’s discovery has just been made in animals and drawn out human brain tumor cells up until now, so until the team can demonstrate comparable results from the drug etomoxir in human trials, we can’t jump to any conclusions.
The scientists also state they’re not all set making any presumptions about how our diets could be linked in the fat versus sugar dispute at this phase.
However any new target for cancer research is something to be carefully positive about, because if anything is going to permit us to lastly beat the enigma that is cancer, it’s going to be a better understanding of what fuels its unrelenting growth.