Exosomes: key players in cancer and potential therapeutic strategy

Abstract

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.

Fig. 1

Exosome biogenesis and its contents. Exosomes originated from MVBs, which contain many kinds of proteins, such as membrane transporters, HSPs and so on. In addition, it also contains a lot of noncoding RNA, including miRNA, lncRNA, and circRNA. These contents play an important role in the development of tumor. MVBs multi-vesicular bodies, CDEs cancer-associated fibroblast-derived exosomes, MSCs mesenchymal stromal cells, CSCs cancer stem cells

Fig. 2

Signal transduction pathway of exosomes in tumor microenvironment. The most important cells in tumor microenvironment mainly include CAFs, CSCs, MSCs, TMICs, etc. These four types of cells use exosomes to promote EMT, tumor metastasis and drug resistance through a variety of mechanisms. CAFs cancer-associated fibroblasts, CSCs cancer stem cells, MSCs mesenchymal stromal cells, TMICs tumor microenvironmental immune cells

Fig. 3

Precisely targeting tumor with engineering exosomes as delivery carrier. Exosomes are carriers with natural delivery ability, which have the characteristics of precisely targeting and high bioavailability. After being loaded into exosomes, anticancer drugs and/or extrinsic ncRNA can directly target cancer cells or CSCs specific pathways, and prevent the further development of tumors. Additionally, the surfaces of exosomes can also be modified with the ligands corresponding to receptors overexpression on cancer cell surfaces, which improving cellular uptake efficiency of exosomes by cancer cells. ncRNA noncoding RNA, CSCs cancer stem cells