Exploiting the message from cancer: the diagnostic value of extracellular vesicles for clinical applications

Liquid biopsy is indispensable for the resolution of current medical issues, such as the cost of developing new drugs and predicting responses of patients to drugs. In this sense, not only the technology for liquid biopsy but also the target biomolecules for biomarkers need to be identified. Extracellular vesicles (EVs), which contain various proteins, including membrane-bound proteins, and RNAs, including mRNA and long/short noncoding RNAs, have emerged as ideal targets for liquid biopsy. These complex biomolecules are covered by a lipid bilayer, which can protect them from degradation. In this review, we review current topics regarding EVs as cancer biomarkers and introduce technologies used for these recently emerged biomolecules. Extracellular vesicles (EVs), small packets of proteins and RNAs secreted by cells and carried in the bloodstream, are promising diagnostic markers for cancer. Developing new markers that can be collected non-invasively can dramatically improve detection and treatment of cancer. EVs secreted by cells, including tumor cells, send messages to distant cells. EVs collected from blood samples can potentially be excellent disease markers. Takahiro Ochiya and Nobuyoshi Kosaka at Tokyo Medical University in Japan and co-workers have reviewed available EV technology. They report that tumors reliably secrete diagnostic EVs, revealing the origin and state of the tumor. Some EVs can even be used to predict whether a cancer might spread to another tissue. With improvement of methods for isolation and standardization, EVs could provide sensitive markers for early diagnosis of many cancers.