BDNF and central nervous system cancer: Overexpressed TUG1 promotes self-renewal of glioma cells by functioning as a molecular sponge for miR-145, an important CSC regulator [157], in the cytoplasm and recruiting Polycomb via YY1 binding activity to repress differentiation genes in the nucleus, such as BDNF(brain derived neurotrophic factor), NGF (nerve growth factor), and NTF3 (neurotrophin 3).