The discovery of a unique DNA signature common to multiple cancers could one day revolutionise the way we diagnose cancer, particularly in its early stages, Australian researchers say.
The cancer marker was identified by scientists at the University of Queensland who have also developed a simple test to detect it in blood and biopsy tissue.
Senior researcher Matt Trau said it had been difficult to find a "simple marker" that would distinguish cancer cells from healthy ones.
"We never thought this would be possible, because cancer is so complicated," said Professor Trau, whose paper is published today in the journal Nature Communications.
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"Even for breast cancer, there are a dozen types, so we thought there would be different tests for different types of cancer."
The researchers were surprised to find the marker appeared in every type of breast cancer they examined, as well as in people with prostate cancer, colorectal cancer and lymphoma.
"That absolutely stunned us," Professor Trau said.
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"It seems to be a general feature for all cancer."
Researchers relied on epigenetics
Cancer is caused by changes in DNA, which controls the way cells function.
"Usually, the approach to find cancer markers … is to look at the sequence of DNA," Professor Trau said.
Taking a different tack, he and his colleagues looked instead at patterns of molecules called methyl groups, which decorate the DNA and control which genes are switched on and off.
The position of these molecules forms part of the epigenome — a set of instructions that controls how genes are expressed.
The researchers found that in healthy cells, methyl groups are spread out across the genome.
But on the genomes of cancer cells, methyl groups were positioned in intense clusters at specific locations.
"Virtually every piece of cancerous DNA we examined had this highly predictable pattern," Professor Trau said.
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"If you think of a cell as a hard-drive … the epigenome is sort of like the apps the cell is running at any one moment.
"It seems that to launch cancer, you have to run a series of genetic apps."
Nanoparticles key to developing test for marker
The researchers developed a test which can detect cancer cells by picking up this epigenetic pattern in blood and biopsy tissue.
The development was made possible after they discovered that placing the cancerous DNA in a solution caused it to fold up into 3D structures.
It turns out these structures stick to gold, so when cancerous DNA is put into a solution with gold nanoparticles, it attaches to them and instantly changes the colour of solution.
"It's just a simple blood test that you can see with a naked eye," said Professor Trau.
The scientists tested the technology on 200 human cancer samples and Professor Trau said the accuracy of cancer detection is as high as 90 per cent.
"You can compare that with some of our frontline cancer detection techniques," he said.
At this stage, the test can only detect the presence of cancer cells, not their type or the stage of the disease.
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The research was funded by the National Breast Cancer Foundation and the researchers are now working with the University of Queensland's commercialisation company UniQuest to further develop the technology.
Still early days
Elin Gray, a senior cancer researcher at Edith Cowan University, said the research was exciting piece of work that offered "a lot of potential".
"It's in early stages and will have to be validated … but I think it's very interesting — it's a totally different approach," Associate Professor Gray said.
Dr Gray, who studies the cancer biomarkers of melanoma, said more work was needed to determine if the test would be useful as a screening tool.
"If it's very sensitive, we could use it for early diagnosis of cancer … especially for cancers where there is no screening paradigm, like ovarian and pancreatic," she said.
Therese Becker, a molecular biologist from the University of New South Wales, agreed the research was "interesting" and required further investigation.
"Like all good science, it raises a lot more questions," she said.
Whether the biomarker is indeed common to all cancers also remains unclear, Dr Gray said.
"It is universal? We don't know until it's tested — it's impossible to know."
Professor Trau said the next stage of the research was to conduct more clinical testing.
"We certainly don't know yet whether it's the holy grail for all cancer diagnostics, but it looks really interesting," he said.