Exosomes: Emerging Players of Intercellular Communication in Tumor Microenvironment

Seminal discoveries have established the role of complex tumor microenvironment (TME) in cancer progression; and later on also uncovered that vesiculation is an integral part of intercellular communication among various cell types in coordinating the tumor assembly in a dynamic manner. Exosomes are small membrane bound endosomal vesicles, which are classically known for their role in discarding cellular wastes; however, recent reports underlined their novel role in malignancy by their release from cells into the TME. Since then, the role of exosomes have been a subject of increasing interest, as exosome mediated intercellular communications offer a novel reciprocal relationship between cancer and stromal cells within the TME and modulate the fate and function of the recipient cells to finally shape the tumor progression. Exosomes are characterised by different features including size, content and mode of delivery; and its cargo delivers interesting bioactive components in the form of proteins, miRNAs or other molecules to the target cell. In the pursuit of further study of exosomes, it was found that with the help of its distinct bioactive components, exosomes specifically regulate tumor growth, angiogenesis, metastasis as well as drug resistance properties. In fact, it acts as a bridge between different signaling networks, present inside the spatially distant cells of the heterogeneous tumor population. In the current endeavour, we have highlighted the role of exosomes in modulating the intercellular crosstalk during tumor growth and progression, and proposed certain novel roles of exosomes to address the few enigmatic questions of cancer cell biology.