Focus on exosomes: novel pathogenic components of leukemia.

Exosomes are released membrane vesicles derived from late endosomes, which share structural and biochemical characteristics with proteasomes. Exosomes are responsible for trafficking proteins, microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) among cells and regulating various cellular processes, such as differentiation, proliferation, migration, invasion, and apoptosis. Although our knowledge of the roles of exosomes in the initiation and progression of leukemia is limited, some studies have indicated that exosomes can encompass many functional factors with an appropriate sorting signal, thereby supporting the metastasis, drug resistance, and immune escape of leukemia cells. This review initially focuses on the biogenesis and composition of exosomes and then summarizes the application of exosomes as a screening biomarker and a potential therapeutic target in leukemia. Many recent reports on the functions of exosomes released from leukemia cells are also discussed, including drug resistance, immune dysfunction, and microenvironment manipulation. Given the critical roles of exosomes in leukemia, understanding the mechanisms regulating the compositions and levels of exosomes, as well as defining exosome functions, will ultimately provide additional insights into the use of exosomes as therapeutic agents for leukemia treatment.