Molecular Dynamics of Trogocytosis and Other Contact-Dependent Cell Trafficking Mechanisms in Tumor Pathogenesis

Horizontal trafficking of subcellular components, such as nucleic acids, proteins, and membrane fragments, is utilized by tumor cells to facilitate tumor cell proliferation and survival. Conventionally, tumor cells have been known to undergo long-range transfer through the import and export of extracellular vesicles and exosomes. However, other means of intercellular transfer are also employed by tumor cells. These trafficking methods can facilitate changes in anti-tumor immunity and distribute oncogenic protein variants to nearby cells to provide a hospitable tumor microenvironment. The molecular mechanisms that drive many of these cell trafficking mechanisms are conserved, relying on de novo synthesis of filamentous actin. However, the delineation between these processes is not yet known. This review will highlight four recently characterized and underappreciated contact-dependent intercellular trafficking mechanisms: (i) trogocytosis, (ii) entosis, (iii) cell fusion, and (iv) tunneling nanotubes/microtubes utilized by tumor cells to promote a hospitable microenvironment.