New device to detect brain tumours using urine

Japanese researchers have developed a new device to identify a key membrane protein in urine that indicates whether the patient has a brain tumour. This protein could be used to detect brain cancer, avoiding the need for invasive tests and increasing the likelihood of tumours being detected early enough for surgery. The team’s research could also have potential implications for detecting other types of cancer, and has been published in the journal ACS Nano.

Although early detection of many types of cancer has contributed to the recent increases in cancer survival rates, the survival rate for brain tumours has remained almost unchanged for over 20 years. This is in part due to their late detection: physicians often discover brain tumours only after the onset of neurological symptoms, such as loss of movement or speech, by which time the tumour has reached a considerable size. Detecting the tumour when it is still small, and starting treatment as soon as possible, should help to save lives.

One possible sign that a person has a brain tumour is the presence of tumour-related extracellular vesicles (EVs) in their urine. EVs are nano-sized vesicles involved in a variety of functions, including cell-to-cell communication. Because those found in brain cancer patients have specific types of RNA and membrane proteins, they could be used to detect the presence of cancer and its progression. Many EVs from cancer cells exist stably and are excreted in the urine without breaking down.

“Liquid biopsy can be performed using many body fluids, but blood tests are invasive,” said Associate Professor Takao Yasui from Nagoya University. “Urine tests are an effective, simple and non-invasive method because the urine contains many informative biomolecules that can be traced back to identify the disease.”

A research group from Nagoya University and The University of Tokyo, co-led by Yasui, has now developed a new analysis platform for brain tumour EVs using nanowires at the bottom of a well plate. Using this device, they identified two specific types of EV membrane proteins, known as CD31/CD63, from urine samples of brain tumour patients. Looking for these tell-tale proteins could enable doctors to identify tumour patients before they develop symptoms.

“Currently, EV isolation and detection methods require more than two instruments and an assay to isolate and then detect EVs,” Yasui said. “The all-in-one nanowire assay can isolate and detect EVs using one simple procedure. In the future, users can run samples through our assay and change the detection part, by selectively modifying it to detect specific membrane proteins or miRNAs inside EVs to detect other types of cancer.

“Using this platform, we expect to advance the analysis of the expression levels of specific membrane proteins in patients’ urinary EVs, which will enable the early detection of different types of cancer.”

Image caption: Microscopic image of nanowires. Image credit: Dr Takao Yasui.