London, Apr 22 : Doctors will now be able to screen for a brain tumour's molecular characteristics without having to perform invasive surgery or biopsy that requires opening the patient's skull, thanks to an Indian origin scientist, who has identified a new fundamental mechanism of how tumour cells communicate.
Dr Abhijit Guha from the University of Toronto and Dr. Janusz Rak at the Research Institute of the McGill University Health Centre (MUHC), found that cancer cells actually communicate with the healthy cells by releasing bubble-like vesicles, called oncosomes, present in blood of cancer patients.
These oncosomes could become a clinical marker to screen tumours without invasive surgery or biopsy, they said.
The researchers said that their finding can ultimately lead to major clinical innovations.
They said that these bubble-like structures contain cancer-causing (oncogenic) proteins that can trigger specific mechanisms when they merge into non or less-malignant cells.
It has been shown that the mutated variant III epidermal growth factor receptor (EGFRvIII), present in tumour cells triggers production of small vesicles that project from the cell membrane, which carry mutated copies of EGFRvIII on their surfaces. Then they were named "oncosomes."
This indicates that oncoproteins are not always confined to the cell that produced them but also migrate. Oncosomes will migrate until they fuse with another cell, either healthy or benign tumoral.
Then, oncogenic protein AGFRvIII becomes accumulated in the membrane of the "recipient" cell and starts stimulating specific metabolic pathways to make it act in an aberrant and malignant way.
"With this information we can imagine that many mutant proteins are not necessarily confined to the cells that make them, but rather can migrate and spread around as cargo of oncosomes, a process that could be referred to as formation of the "oncogenic field effect. It demonstrates that cancer is a multi-cell process, where the cells talk to one another extensively. This goes against the traditional view that a single 'mutated' cell will simply multiply uncontrollably to the point of forming a tumour. This discovery opens exciting new research avenues, but we also hope that it will lead to positive outcomes for patients," Nature quoted Dr. Rak, as saying.
Indeed, the presence of oncosomes (containing EGFRvIII or other proteins) in blood of cancer patients could become a clinical marker enabling the doctors to screen for a tumour's molecular characteristics instead of having to perform invasive surgery or biopsy.
Right now, in the case of brain cancer, this particular assessment cannot be performed without removing the tumour and therefore opening a patient's skull. But further research in oncosomes would potentially only require taking a small sample of blood or cerebrospinal fluid.
This would make it possible to develop a personalized therapy for such patients.
The study is published in the on-line edition of Nature Cell Biology.