Exosomes are extracellular vesicles secreted by most eukaryotic cells and participate in intercellular communication. The components of exosomes, including proteins, DNA, mRNA, microRNA, long noncoding RNA, circular RNA, etc., which play a crucial role in regulating tumor growth, metastasis, and angiogenesis in the process of cancer development, and can be used as a prognostic marker and/or grading basis for tumor patients. Hereby, we mainly summarized as followed: the role of exosome contents in cancer, focusing on proteins and noncoding RNA; the interaction between exosomes and tumor microenvironment; the mechanisms that epithelial-mesenchymal transition, invasion and migration of tumor affected by exosomes; and tumor suppression strategies based on exosomes. Finally, the application potential of exosomes in clinical tumor diagnosis and therapy is prospected, which providing theoretical supports for using exosomes to serve precise tumor treatment in the clinic.
Introduction
Exosomes, with a size range of 40–160 nanometers in diameter (averaging 100 nanometers), are a subset of extracellular vesicles (EVs) surrounded by a lipid bilayer membrane and secreted by most eukaryotic cells,1 Identified as early as in late 1980s, exosomes were originally and simply considered as cellular waste products.2 However, with the development of research methodologies and techniques, people now have realized that exosomes represent a novel mode of intercellular communication and contribute to a wide range of biological processes in health and disease including cancer.3 The biological function of exosome relies on its bioactive cargos, such as lipids, metabolites, proteins and nucleic acids,4,5,6,7 which can be delivered to the target cells. Growing evidence suggests that tumor-derived exosomes (TEXs) play critical roles in cancer. Exosomes and their cargos may serve as cancer prognostic marker, therapeutic targets or even as anticancer drug‐carrier.8 In this review, we endeavor to summarize the bioactive exosomal contents focusing on proteins and noncoding RNAs, clarify the crosstalk of exosome with tumor microenvironment (TME), elucidate the underlying mechanism of affected epithelial-mesenchymal transition (EMT), invasion and migration affected by exosomes, and discuss the future tumor suppression strategies based on exosomes.
