BDNF and neoplasm: In a variety of malignant tumors, the interaction between neuronal signaling and cancer stem cells not only stimulates tumor growth but also represents a potential therapeutic target against CSCs (105–107).Numerous studies have demonstrated that neurotrophic factors (such as NGF and BDNF) and their receptors (such as TrkA and p75NTR), neurotransmitters (such as dopamine and acetylcholine), as well as other neural system components, exert direct or indirect regulatory effects on CSCs.