Regulation of NGF responsiveness in human neuroblastoma.
Functional nerve growth factor (NGF) responsiveness was investigated in human neuroblastoma (NB) cell lines in vitro and retinoic acid (RA) was found to transcriptionally enhance expression of the trkA, but not the trkB gene in GOTO cells, while the reverse was found in HTLA230 NB cells. Ciliary neurotrophic factor (CNTF) specifically induced trkA gene transcription in both cell lines. Transcriptional activation of the trkA gene increased total trkA protein and surface bound receptor, which was tyrosine phosphorylated upon NGF stimulation inducing immediate early response gene transcription (i.e. c-fos, Egr-1). Newly synthesized trkA protein had a molecular weight of 110 kDa and was post-translationally modified. Rapid down regulation of the receptor protein occurred upon NGF stimulation, despite the presence of high levels of trkA mRNA, due to an increased rate of receptor degradation. Transient DNA synthesis and cell proliferation upon NGF treatment occurred in GOTO cells with elevated trkA expression. In contrast, NGF induced neuronal differentiation in HTLA230 cells expressing the endogenous trkA receptor gene, despite the lack of p75 expression. Hence, transcriptional activation of trkA gene expression can be achieved by different signal pathways in human NB cells, but NGF can act either as mitogen or inducer of cell differentiation, depending on the tumor from which cells are derived.
Bogenmann
E
E
Division of Hematology/Oncology, Childrens Hospital Los Angeles, California 90027, USA.
Peterson
S
S
Maekawa
K
K
Matsushima
H
H
D020934:Ciliary Neurotrophic Factor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051766:Early Growth Response Protein 1; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017874:Immediate-Early Proteins; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009419:Nerve Tissue Proteins; D009447:Neuroblastoma / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D020801:Receptor, Ciliary Neurotrophic Factor; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D020934:Ciliary Neurotrophic Factor; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D020801:Receptor, Ciliary Neurotrophic Factor; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D014157:Transcription Factors; D014212:Tretinoin; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA