A study by Japanese researchers suggests that microRNAs in urine could be promising biomarkers for diagnosing brain tumors at an early stage. The results are published in the journal ACS Applied Materials &Interfaces .
Diagnosis of brain tumors is usually made after patients have undergone a CT scan or MRI. However, the latter are offered after the appearance of neurological symptoms, such as immobility of the limbs and the inability to speak. The problem is that at this stage, the tumors are already too massive to be completely eliminated, which inevitably reduces the survival rate of patients. As part of a study, researchers from the University of Nagoya have developed a test to advance the diagnosis.
For several years, urine tests – like blood tests – have been developed to detect the presence of cancers non-invasively before the typical clinical symptoms appear. The idea, roughly, is to take a sample of fluid and analyze it by focusing on biomarkers correlated to the disease . This work has shown promise with cancers of the bladder, pancreas or prostate, in particular.
Until now, however, there was no means of early detection for tumors of the central nervous system (CNS).
It is indeed difficult to propose a liquid biopsy for a blood test insofar as the blood-brain barrier tends to restrict molecular exchanges between the parenchyma and the blood. On the other hand, urine-based liquid biopsy has not received much attention due to the lack of a satisfactory way to collect urine biomarkers.
As part of a new study, the Nagoya team focused on this last point. Their idea:rely on microRNA , small nucleic acid molecules secreted by various cells and present in a stable and intact state in biological fluids such as blood and urine.
“Urine-based liquid biopsy had not been fully studied for patients with brain tumors, as none of the conventional methodologies can effectively extract the urine microRNA in terms of varieties and amounts” , explains Prof. Atsushi Natsume. “So we decided to develop a device that could do this” .
The newly developed device consists of one hundred million zinc oxide nanowires capable of extracting a greater variety and quantity of microRNAs from just one milliliter of urine compared to conventional methods. These nanowires, the researchers note, can also be sterilized and mass-produced .
After extracting these molecules, Professor Natsume's team tested their value as a biomarker of brain tumors. To do this, they used a diagnostic model based on microRNA expression in urine samples from brain tumor patients and non-cancer individuals. According to the study, this model could distinguish cancer patients from those in the control group with a ne sensitivity of 100% and a specificity of 97% , regardless of malignancy and tumor size.
Additional work will obviously be required before we can take full advantage of this new technique, but it looks very promising. For researchers, it could be useful for the early detection of aggressive types of brain cancer, such as glioblastoma , but also for other types of cancer.
