Technique developed to detect cancer early

University of Florida researchers have developed a technique they believe will allow easy detection of a wide variety of cancers even before symptoms appear.

The technique, reported online in the Proceedings of the National Academy of Sciences, involves introducing molecularly engineered strands of the genetic material, DNA, into cell cultures to see whether they produce a fluorescent light after binding to cancer proteins.

"We are able to detect cancer-related proteins very easily with this approach, which is really promising in terms of its potential for early diagnosis of cancer," study author and UF chemistry professor Weihong Tan said yesterday.

He explained that the technique relies on fluorescent molecules engineered into tiny strands of DNA, or its cousin, genetic messenger RNA. The strands act as molecular beacons, readily attaching to a sought-after substance, such as a cancer protein.

In their research, Mr. Tan and colleagues were looking for a protein known as platelet derived growth factor (PDGF), which regulates cell growth and division.

"In a cancer patient, there are high concentrations of PDGF. But concentrations are low in a normal patient," said Mr. Tan, also a member of the UF Genetics Institute and associate director of the school's Center for Research.

The scientists' achievement ?? so far limited to the laboratory ?? could enable doctors to search within extremely complex fluid or tissue samples to identify cancer biomarkers that pinpoint evidence of either new cancer or residual cancer in patients after treatment.

"Even when there are few cancer protein molecules, which are in extremely low concentrations, we have been able to detect them," said Mr. Tan.

"This technique has a lot of implications ... for much earlier diagnosis of cancer than current practices, which require looking at peoples' cancer tissue," he said.

It can be hard to distinguish a medical threat in such tissue, if it's early in the disease, as well as concerns about discovering it too late, he said.

The authors noted that elevated PDGF levels have been linked to different cancer types and have been found in patients with malignancies of the lungs, kidneys, ovaries, brain and pancreas.

What separates this research from work done previously is that the UF team found a way to sort through "background signals" coming from both the probe used to detect cancer proteins and the biological fluids where the proteins reside. That problem was overcome, said Mr. Tan, by "engineering a molecular switch that turns on the fluorescence."

Co-author Nicholas Turro, a chemistry professor at Columbia University, said the probe's green fluorescent burst lasts little more than a nanosecond, or a billionth of a second. But he said that is enough time to separate it from surrounding signals. That fluorescent light is a clear indication of the presence of PDGF.