From Technology Networks by Alison Halliday –
Evidence is mounting for exosomes playing a central role in many aspects of cancer biology. As researchers start to unravel the secrets of these elusive little vesicles, this is opening a host of exciting new opportunities to tackle cancer – from non-invasive diagnostics to innovative new therapeutics.
Exosomes are thought to be a specific class of vesicle that arise from multivesicular bodies (MVBs) and are released from cells. Around 50 to 150 nanometres in size, these tiny membrane-wrapped packages contain a variety of cargo – such as small molecules, proteins or nucleic acids.
However, with no markers available to distinguish them from other vesicles, exosomes are difficult to define – and their nomenclature is currently a subject of hot debate.
“I quite like the term exosomes because that’s what I think I’m studying – but I can’t prove it!” says Professor Aled Clayton of the Division of Cancer and Genetics at the University of Cardiff, UK.
“The umbrella term that is probably more correct is extracellular vesicles, which also includes larger plasma membrane-derived vesicles that are structurally and physically quite different.”
As well as what to call them, the role of exosomes in healthy systems is also unclear.
“We think they may facilitate a few things, one is potentially to remove unwanted proteins that may have misfolded, and another is to transfer information between cells,” says Dr Richard Kelwick, a Research Associate at Imperial College London, UK.
Exosomes are integral in cancer biology
However, there is an increasing number of studies pointing the finger at exosomes in many aspects of cancer development, including hypoxia driven epithelial-mesenchymal transition (EMT), cancer stemness, angiogenesis, metastasis and modulating the immune response.
“Just think of everything that tumors need to do – these vesicles are in some fashion involved,” says Clayton.
Exosomes may even help explain why particular cancer types show a preference for metastatic spread to specific organs.