Tunneling nanotube‐like structures in brain tumors

Background Diffuse astrocytomas, including glioblastomas, are malignant brain tumors with notorious resistance to standard therapies. One hallmark of malignant gliomas is their highly infiltrative growth. To allow long‐range communication, exchange of molecules, and cell‐cell contact between these scattered tumor cells, mechanisms other than paracrine signaling seem requisite. Recent findings We recently described long and thin membrane tubes (tumor microtubes, or TMs) that interconnect single glioma cells to a functional network. The integration of cells into these networks protected them from the cytotoxic effects of radiotherapy and chemotherapy. There is growing interest in cell protrusions, membrane tubes, and cell‐cell connections today, not only in cancer research. For the first time, so‐called tunneling nanotubes (TNTs) were described as thin intercellular membrane tubes in 2004. Until now, such membrane tube connections have not only been described in diffuse astrocytomas, but also in other tumor entities and other diseases. Conclusion Here, we want to review the biological functions of TMs, their similarities and differences to TNTs and other cellular protrusions, as well as potential clinical applications.