Resistance to chemotherapy mediated by TrkB in neuroblastomas

Cancer Res. 2002 Nov 15;62(22):6462-6.

Abstract

Neuroblastoma is a common childhood tumor derived from the peripheral nervous system. Favorable neuroblastomas usually express TrkA, the receptor for nerve growth factor (NGF), whereas unfavorable, MYCN-amplified neuroblastomas usually express TrkB and its ligand, brain-derived neurotrophic factor (BDNF). Here, we provide evidence that the TrkB-BDNF pathway is associated with enhanced survival and resistance to chemotherapy in neuroblastoma. 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. Cells were exposed in vitro to chemotherapy agents used to treat neuroblastomas: doxorubicin, etoposide (VP16), and cisplatin. Chemoresistance was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cell survival and by ELISA for cell death. In all cases, the TrkB-expressing subclones were more resistant to treatment than the parent line. Furthermore, when the TrkB tyrosine kinase was blocked with the Trk-specific inhibitor CEP-2563, or by neutralizing antibody to BDNF, sensitivity to chemotherapy was significantly increased. We also found constitutive phosphorylation of AKT at the Ser-473 site in TrkB transfectants, whereas there was only a minimal level of constitutive phosphorylation of AKT in SY5Y cells. These results show that the TrkB-BDNF pathway provides a survival advantage when exposed to DNA-damaging reagents, and, therefore, this autocrine pathway may play an important role in mediating the drug-resistant phenotype associated with TrkB-expressing neuroblastomas. Activation of PI3K/AKT survival pathway may contribute to the increased drug resistance in TrkB-expressing neuroblastomas.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antibodies / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Brain-Derived Neurotrophic Factor / antagonists & inhibitors
  • Brain-Derived Neurotrophic Factor / biosynthesis
  • Brain-Derived Neurotrophic Factor / genetics
  • Brain-Derived Neurotrophic Factor / immunology
  • Cisplatin / pharmacology
  • Doxorubicin / pharmacology
  • Drug Resistance, Multiple / physiology*
  • Drug Resistance, Neoplasm
  • Enzyme Inhibitors / pharmacology
  • Etoposide / pharmacology
  • Humans
  • Neuroblastoma / drug therapy*
  • Neuroblastoma / genetics
  • Neuroblastoma / metabolism
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Receptor, trkB / genetics
  • Receptor, trkB / metabolism
  • Receptor, trkB / physiology*
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Antibodies
  • Brain-Derived Neurotrophic Factor
  • Enzyme Inhibitors
  • Etoposide
  • Doxorubicin
  • Protein-Tyrosine Kinases
  • Receptor, trkB
  • Cisplatin