Figure 1.

Exosome-mediated epigenetic regulation of cancer therapy resistance. Within the tumor microenvironment, various cell types communicate with each other leading to conditions favoring aggressive tumors and resistance against therapies, with exosomes playing an important role in cellular communications. Exosomes are released by various cell types and they transport epigenetic factors such as miRNAs, lncRNAs and circRNAs, in addition to carrying methyltransferases, all of which bring about epigenetic modifications in the recipient cells, resulting in the induction of EMT, cancer stem cell phenotype and cellular signaling pathways that favor cancer cell migration, invasion, angiogenesis, metastasis and therapy resistance. CAFs: cancer-associated fibroblasts, EMT: epithelial–mesenchymal transition, lncRNA: long non-coding RNA, miRNA: microRNA, mTOR: mammalian target of rapamycin, TAMs: tumor-associated macrophages.