Apoptotic cell death in TrkA-overexpressing cells: kinetic regulation of ERK phosphorylation and caspase-7 activation.
The TrkA tyrosine kinase is activated by autophosphorylation in response to NGF, and plays an important role in cell survival, differentiation, and apoptosis. To investigate its role in cell fate determination, we produced stable TrkA-inducible SK-N-MC and U2OS cell lines using the Tet-On system. Interestingly, TrkA overexpression induced substantial cell death even in the absence of NGF, by stimulating ERK phosphorylation and caspase-7 activation leading to PARP cleavage. TrkA-mediated cell death was shown by the annexin-V binding assay to be, at least in part, apoptotic in both SK-N-MC and U2OS cells. Furthermore, the truncated form (p18) of Bax accumulated in the TrkA-induced cells, suggesting that TrkA induces mitochondria-mediated apoptosis. NGF treatment augmented the cell death induced by TrkA overexpression. This TrkA-induced cell death was blocked by the tyrosine kinase inhibitors, K-252a and GW441756. Moreover, TrkA overexpression inhibited long-term proliferation of both the neuronal SK-N-MC cells and the non-neuronal U2OS cells, suggesting a potential role of TrkA as a tumor suppressor.
Department of Biochemistry and RINS, MRCND and Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju 660-751, Korea.
Eun Joo
EJ
Jung
Deok Ryong
DR
Kim
D017209:Apoptosis; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000378:metabolism / Q000473:pathology*; D053179:Caspase 7 / Q000378:metabolism*; D003114:Colony-Forming Units Assay; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D020932:Nerve Growth Factor / Q000494:pharmacology; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology*; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D020917:Receptor, trkA / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D020932:Nerve Growth Factor; D020917:Receptor, trkA; D048049:Extracellular Signal-Regulated MAP Kinases; D053179:Caspase 7