A tumor with a functional nerve growth factor receptor may be dependent on the neurotrophin nerve growth factor for survival and may regress in its absence, allowing a new approach to the treatment of certain patients with neuroblastoma.
We have used the human neuroblastoma cell line SH-SY5Y as a model system to investigate the expression and regulation of the receptors for brain-derived neurotrophic factor (BDNF), a member of the nerve growth factor (NGF) family of neurotrophins.
In summary, the study of neurotrophin receptor expression and function in neuroblastomas may provide important insights into the role that these pathways play in the pathogenesis and clinical behavior of this tumor.
Neuroblastomas express neurotrophin receptors and high levels of mRNA for trk-A correlates with favourable outcome, whereas trk-B mRNA is expressed by more unfavourable tumours.
Here we demonstrate that NGF-but not neurotrophin-3 (NT-3) or brain-derived neurotrophic factor (BDNF)-induced apoptosis in p75NTR-expressing human neuroblastoma SK-N-MC cells.BDNF prevented NGF-induced apoptosis.
Extracellular-regulated kinases and phosphatidylinositol 3-kinase are involved in brain-derived neurotrophic factor-mediated survival and neuritogenesis of the neuroblastoma cell line SH-SY5Y.
We tested whether brain derived neurotrophic factor (BDNF) protects neuroblastoma (NB) cells from cytotoxic agents using a model NB cell line, NB 1643, which expresses functional tropomyosin related kinase B (TRKB) following treatment with all-trans-retinoic acid.TRKB is the receptor for BDNF.
SK-N-BE neuroblastoma cell clones transfected with p75(NTR) and lacking Trk neurotrophin receptors, previously reported to undergo extensive spontaneous apoptosis and to be protected by nerve growth factor (NGF) (Bunone, G., Mariotti, A., Compagni, A., Morandi, E., and Della Valle, G. (1997) Oncogene 14, 1463-1470), are shown to exhibit (i) increased levels of the pro-apoptotic lipid metabolite ceramide and (ii) high activity of caspases, the proteases of the cell death cascade.
Activation of the neurotrophin receptor TrkA by its ligand nerve growth factor (NGF) initiates a cascade of signaling events leading to neuronal differentiation in vitro and might play an important role in the differentiation of favorable neuroblastomas (NB) in vivo.
We transfected the neuroblastoma line SH-SY5Y, which has endogenous expression of BDNF, with a full-length TrkB expression vector, and obtained clones with moderate or high levels of expression.
By using neuroblastoma cell clones lacking the expression of all neurotrophin receptors or engineered to express full-length or various truncated forms of p75(NTR), we could show that p75(NTR) is involved in the direct signaling of cell death by Abeta via the function of its death domain.
High expression of the neurotrophin receptor TrkA in neuroblastomas (NBs) is associated with a favorable prognosis, whereas TrkB is mainly expressed on aggressive, MYCN-amplified NBs.
This shows that MYCN overexpression per se is not sufficient to induce trkB expression. trkB expression and BDNF responsiveness in neuroblastoma cells can be induced by all-trans-retinoic acid (RA).
However, the spontaneous regression of neuroblastoma mimics the programmed cell death normally occurring in developing sympathetic cells expressing both TrkA tyrosine kinase A and p75NTR neurotrophin receptor.