Tunneling Nanotubes: Implications for Chemoresistance.

Tunneling nanotubes (TNTs) are thin, membranous protrusions that connect cells and allow for the transfer of various molecules, including proteins, organelles, and genetic material. TNTs have been implicated in a wide range of biological processes, including intercellular communication, drug resistance, and viral transmission. In cancer, they have been investigated more deeply over the past decade for their potentially pivotal role in tumor progression and metastasis. TNTs, as cell contact-dependent protrusions that form at short and long distances, enable the exchange of signaling molecules and cargo between cancer cells, facilitating communication and coordination of their actions. This coordination induces a synchronization that is believed to mediate the TNT-directed evolution of drug resistance by allowing cancer cells to coordinate, including through direct expulsion of chemotherapeutic drugs to neighboring cells. Despite advances in the overall field of TNT biology since the first published report of their existence in 2004 (Rustom A, Saffrich R, Markovic I, Walther P, Gerdes HH, Science. 303:1007-10, 2004), the mechanisms of formation and components vital for the function of TNTs are complex and not yet fully understood. However, several factors have been implicated in their regulation, including actin polymerization, microtubule dynamics, and signaling pathways. The discovery of TNT-specific components that are necessary and sufficient for their formation, maintenance, and action opens a new potential avenue for drug discovery in cancer. Thus, targeting TNTs may offer a promising therapeutic strategy for cancer treatment. By disrupting TNT formation or function, it may be possible to inhibit tumor growth and metastasis and overcome drug resistance.