Constitutively active TrkB confers an aggressive transformed phenotype to a neural crest-derived cell line. Academic Article uri icon

abstract

  • Neuroblastoma arises from sympathoadrenal progenitors of the neural crest and expression of the neurotrophin receptor TrkB and its ligand, brain-derived neurotrophic factor (BDNF), is correlated with poor prognosis. Although activated TrkB signaling promotes a more aggressive phenotype in established neuroblastoma cell lines, whether TrkB signaling is sufficient to transform neural crest-derived cells has not been investigated. To address the role of TrkB signaling in malignant transformation, we removed two immunoglobulin-like domains from the extracellular domain of the full-length rat TrkB receptor to create a ?IgTrkB that is constitutively active. In the pheochromocytoma-derived cell line PC12, ?IgTrkB promotes differentiation by stimulating process outgrowth; however, in the rat neural crest-derived cell line NCM-1, ?IgTrkB signaling produces a markedly transformed phenotype characterized by increased proliferation, anchorage-independent cell growth, anoikis resistance and matrix invasion. Furthermore, expression of ?IgTrkB leads to the upregulation of many transcripts encoding cancer-associated genes including cyclind1, twist1 and hgf, as well as downregulation of tumor suppressors such as pten and rb1. In addition, ?IgTrkB NCM-1 cells show a 21-fold increase in mRNA for MYCN, the most common genetic marker for a poor prognosis in neuroblastoma. When injected into NOD SCID mice, control GFP NCM-1 cells fail to grow whereas ?IgTrkB NCM-1 cells form rapidly growing and invasive tumors necessitating euthanasia of all mice by 15 days post injection. In summary, these results indicate that activated TrkB signaling is sufficient to promote the formation of a highly malignant phenotype in neural crest-derived cells.

publication date

  • February 20, 2014