Novel urine test diagnoses brain tumor by identifying DNA biomarker

The catch-and-release test uses zinc oxide (ZnO) nanowire surfaces to trap cfDNA effectively.  
Mrigakshi Dixit
Urine tests identify brain tumors by capturing cancer-derived extracellular vesicles and DNA using nanowires.
Urine tests identify brain tumors by capturing cancer-derived extracellular vesicles and DNA using nanowires.

Takao Yasui 

For the first time, a urine test has been developed to identify brain tumors in a non-invasive manner. 

Tissue biopsy is the most often used approach for diagnosing brain tumors nowadays. It is an invasive method requiring surgery to take a tiny amount of tumor tissue for microscopic inspection.

Nagoya University in Japan has developed a novel method that may aid in diagnosing brain tumors faster and more timely. Nanowires are used in this newly developed method to "capture and release cell-free DNA" (cfDNA) in urine. 

Through this method, the team detected an IDH1 mutation linked to gliomas, a type of brain tumor. 

Use of tumor biomarker  

The official release highlighted that many people are subjected to routine medical examinations that include the collection of urine samples. These samples might be used for tumor testing to check for a cancer biomarker cfDNA. 

When tumor cells divide and destroy healthy cells, these tiny DNA particles are discharged into the bloodstream and other bodily fluids. 

The presence of cfDNA is naturally cleared up by white blood cells; but in the case of cancer, where cells reproduce faster than healthy cells, there is an excess of remaining cfDNA that WBCs cannot efficiently clear. These are thus eliminated in the urine.  

The catch-and-release test uses zinc oxide (ZnO) nanowire surfaces to trap cfDNA effectively.  

The scientists chose zinc oxide because water molecules adsorb on its nanowire surface. This enables water molecules to bond hydrogen with the cfDNA in the urine sample. And that’s how researchers may extract traces of cfDNA from the sample.

“We succeeded in isolating urinary cfDNA, which was exceptionally difficult with conventional methods,” said Professor Takao Yasui in an official release.

“Although in a previous experiment, we showed that our nanowire could capture cancer extracellular vesicles, which we found in this sample too; the surprising thing was the capture of cfDNA using a similar technique. When we extracted the cfDNA, we detected the IDH1 mutation, which is a characteristic genetic mutation found in gliomas. This was exciting for us, as this is the first report of the detection of the IDH1 mutation from a urine sample as small as 0.5 ml,” added Yasui. 

Brain tumors are often diagnosed at an advanced stage only after symptoms such as limb paralysis emerge. And even when they are detected, they are at the advanced stage, making surgical removal challenging and sometimes impossible. 

The researchers hope their nanowire-detecting approach could be used to make early cancer diagnoses in the near future. 

The findings have been reported in the journal Biosensors and Bioelectronic

Study abstract:

Cell-free DNA (cfDNA) and extracellular vesicles (EVs) are molecular biomarkers in liquid biopsies that can be applied for cancer detection, which are known to carry information on the necessary conditions for oncogenesis and cancer cell-specific activities after oncogenesis, respectively. Analyses for both cfDNA and EVs from the same body fluid can provide insights into screening and identifying the molecular subtypes of cancer; however, a major bottleneck is the lack of efficient and standardized techniques for the isolation of cfDNA and EVs from clinical specimens. Here, we achieved catch-and-release isolation by hydrogen bond-mediated binding of cfDNA in urine to zinc oxide (ZnO) nanowires, which also capture EVs by surface charge, and subsequently, we identified genetic mutations in urinary cfDNA. The binding strength of hydrogen bonds between single-crystal ZnO nanowires and DNA was found to be equal to or larger than that of conventional hydrophobic interactions, suggesting the possibility of isolating trace amounts of cfDNA. Our results demonstrated that nanowire-based cancer screening assay can screen cancer and can identify the molecular subtypes of cancer in urine from brain tumor patients through EV analysis and cfDNA mutation analysis. We anticipate our method to be a starting point for more sophisticated diagnostic models of cancer screening and identification.

Add Interesting Engineering to your Google News feed.
Add Interesting Engineering to your Google News feed.
message circleSHOW COMMENT (1)chevron
Job Board