Exosomes: Critical Mediators of Tumour Microenvironment Reprogramming.

Tumour microenvironment (TME) is a resident of a variety of cells, which are devoted to the heterogeneous population of the tumour. TME establishes a communication network for crosstalk and signalling between tumour cells, stroma, and other interstitial cells. The cross-communication drives the reprogramming of TME cells, which promote cancer progression and metastasis via diverse signalling pathways. Recently, TMEderived exosomes are recognized as critical communicators of TME cell reprogramming. This review addresses the role of TME-derived exosomes in the modulation of stroma, including reprogramming the stromal cells, ECM and tumour cell metabolism, as well as neoplastic transformation. Subsequently, we described the role of exosomes in pre-metastatic niche development, maintenance of stemness and tumour vasculature, as well as development of drug resistance. We also explored tumour-derived exosomes in precision, including diagnosis, drug delivery, and vaccine development. We discussed the currently established bioengineered exosomes as carriers for chemotherapeutic drugs, RNAi molecules, and natural compounds. Finally, we presented tetraspanin and DNA-based precision methods for the quantification of tumour-derived exosomes. Overall, TMEderived exosome-mediated reprogramming of TME and precision strategies could illuminate the potential mechanisms for targeted therapeutic intervention.