RESUMO
Neurotrophins are structurally related growth polypeptide factors that play an essential role in the development and functioning of the vertebrate nervous system. They provide forming and survival of different neuron populations of the central and peripheral nervous system. Neurotrophins are also involved in the processes of higher nervous activity. Neurotrophins are active not only in the nervous system; these universal trophic factors are important for the development, proliferation, and maintaining of different tissues including tumor tissues. Changes in the neurotrophin signaling system are significant for the pathogenesis of malignancies at the initiation stage as well as during the tumor progression. Neurotrophins and their receptors are complex multi-component system controlled in a very complicated manner. This system can affect the cells and tissues in different ways; the final results of neurotrophin action vary from cell maintenance and survival to apoptosis. Differences in mechanisms and results of the neurotrophin action depend on the cell and tissue type in which the system works. The effects of the neurotrophin signaling are especially variable in different malignancies. In the review we summarize the information on the neurotrophin signaling in various tumors and demonstrate its contribution to the disease course.