Cancer DNA Binds To Gold That Could Lead To New Cancer Blood Test

January 23, 2021

Researchers have discovered strange differences between the DNA of cancer cells and that of healthy cells, a finding that could lead to a new blood test for cancer.

What’s the difference? Cancer DNA has a fairly strong affinity for gold, according to a new study. Researchers say this feature appears to be common to cancer DNA, regardless of the type of cancer.

Using this finding, the researchers devised a new test that uses gold nanoparticles to detect cancer. The gold particles change color based on the presence or absence of cancer DNA. The result is a simple and quick test that can detect cancer in as little as 10 minutes, according to the study published today (Dec. 4) in the journal Nature Communications.

“You can detect it by eye – it’s that simple,” senior study author Matt Trau, a professor and senior team leader at the Australian Institute for Bioengineering and Nanotechnology at the University of Queensland, said in a statement.

However, the work is preliminary and more research is needed before the test can be useful to patients, outside experts told Live Science.

Cancer DNA “methyl landscape”
The new research focuses on the “epigenome,” or chemical modifications to DNA that turn genes “on” or “off.” These modifications do not change the DNA sequence, but rather affect how the cell “reads” the gene. An example of an epigenetic change is DNA methylation, which is the addition of a methyl group or “chemical cap” to a part of the DNA molecule. This modification prevents the expression of certain genes.

Previous studies have shown that the pattern of DNA methylation in cancer cells differs from the methylation pattern in healthy cells. Specifically, cancer cell DNA has clusters of methyl groups at specific locations and little or no methylation elsewhere, while normal DNA has methyl groups more evenly distributed throughout the genome. Researchers refer to this methylation pattern as the “methylscape” or “methylation landscape.”

And while this “methylscape” can be used as a biomarker for cancer, researchers don’t have a good way to detect it.

So in the new study, instead of focusing on methylation itself, the researchers looked at the effects of methylation on the overall structure and chemistry of cancer DNA.

The researchers found that the methylation landscape of cancer DNA causes DNA fragments to fold into 3D “nanostructures” that have an affinity for gold. In contrast, normal DNA folds somewhat differently and does not result in such a strong affinity for gold, the researchers said.

Therefore, the researchers developed a test method that takes advantage of this ability of cancer DNA to adhere to gold. If cancer DNA is present, the gold nanoparticles turn a different color than they would if cancer DNA were not present. The test can use “circulating free DNA,” or DNA released into the bloodstream from cancer or healthy cells.

Researchers have already tested their technique on samples from about 200 cancer patients and healthy people and found the test to be 90 percent accurate in detecting cancer.

A new cancer test?
Dr. Jeffrey Weber, associate director of NYU Langone Health’s Perlmutter Cancer Center, called the new study “great science” and applauded the idea of finding ways to detect the cancer’s DNA methyl landscape. However, Weber, who was not involved in the study, said the work is “just the beginning.” He added that larger studies are needed to assess the accuracy of the test and whether it could be useful to patients, compared to existing tests.

“It’s going to be a lot of work to turn this [test] into a real, clinically useful [test],” Weber told Live Science.

Joyce Ohm, an associate professor of oncology at the Roswell Park Comprehensive Cancer Center in Buffalo, New York, agreed that the work is “an exciting potential advance” in the search for general epigenetic biomarkers for cancer. But she added that the study “is very much a proof of principle at this point.”

Currently, the test only detects the presence of cancer, not the type of cancer. It’s also unclear exactly how high the level of cancer DNA needs to be in order for the test to work, which would affect how early in the disease process the test is used, the researchers said.

Ohm told Live Science that in its current form, the test would be less useful as a screening test because it doesn’t detect the type of cancer. But if the technology is developed further, perhaps the most immediate potential application would be to monitor the recurrence of disease in existing cancer patients, she said.

The researchers acknowledge that their test needs further study, “but it looks really interesting as an incredibly simple ‘universal marker’ for cancer,” Trau said in a statement. It’s also appealing “as a very convenient and inexpensive technique that doesn’t require complex laboratory equipment like DNA sequencing,” he said.