Tunneling Nanotubes: A Versatile Target for Cancer Therapy.

Currently Cancer is the leading cause of death worldwide. Malignancy or cancer is a class of diseases characterized by uncontrolled cell growth that eventually invade other tissues and develop secondary malignant growth at other sites by metastasis. Intercellular communication plays a major role in cancer, particularly in the process of cell proliferation and coordination which in turn leads to tumor invasion, metastasis and development of resistance to therapy. Cells communicate among themselves in a variety of ways, namely: i) via gap junctions with adjacent cells; ii) via exosomes with nearby cells; and iii) via chemical messengers with distant cells. Besides, cell - cell connection by tunneling nanotubes (TnTs) is recently gaining importance where intercellular components are transferred between cells. In general cell organelles like Golgi vesicle and mitochondria; and biomolecules like nucleic acids and proteins are transferred through these TnTs. These TnTs are long cytoplasmic extensions made up of actin that function as intercellular bridge and connect a wide variety of cell types. Malignant cells form TnTs with either other malignant cells or cells of the surrounding tumor matrix. These TnTs help in the process of initiation of tumor formation, its organization and propagation. The current review focuses on the role of TnTs mediated cell - cell signaling in cancer micro-environment. Drugs that inhibit TnT-formation such as metformin and everolimus can be targeted towards TnTs in the management of cancer growth, proliferation, tumor invasion and metastasis.