Figure 2.

Summary of the roles of BCEVs in cancer, the tumor microenvironment and therapeutic applications. BCEVs are involved in many aspects of cancer development and progression. Like other cancer cells, BC cells release EVs into extracellular spaces and can be received by urothelial cells and immune cells, consequently modifying their behavior to support or suppress tumor growth (red and blue arrows indicate the migrating direction of intracellular vesicles). On the one hand, BCEVs can promote neighboring recipient cells’ cancerous behaviors, including malignant transformation, proliferation, migration and invasion, as well as modify the tumor microenvironment in favor of tumor outgrowth, including promoting inflammation, ECM remodeling and fibroblast differentiation to cancer-associated fibroblasts (CAF). In contrast, BCEVs also participate in the immune surveillance system by presenting tumor antigens to provoke dendritic and cytotoxic T cell anti-tumor immunity. With specific cargoes carried by BCEVs such as miRNA, lncRNA and proteins, their clinical application, particularly in disease biomarkers, has rapidly expanded. Moreover, researching the utilization of BCEVs as vesicles to deliver therapeutic materials is also underway.