Different effects of TrkA expression in neuroblastoma cell lines with or without MYCN amplification.
BACKGROUND
Expression of the neurotrophin receptor TrkA is associated with a favorable prognosis in neuroblastoma (NB) and promotes growth inhibition and neuronal differentiation. Aggressive, MYCN-amplified NB tumors express little or no TrkA mRNA, suggesting that MYCN overexpression may inhibit TrkA expression.


METHODS
To study the interactions of TrkA expression and MYCN amplification in NB, we stably expressed the TrkA receptor in the MYCN single copy cell lines SH-SY5Y and NB69 as well as in the MYCN amplified cell lines CHP134 and IMR5.


RESULTS
All four transfected cell lines demonstrated high TrkA expression and similar activation of the TrkA receptor and of mitogen-activated protein kinases as well as induction of immediate-early genes in response to nerve growth factor (NGF). Introduction of TrkA restored NGF responsiveness of SH-SY5Y and NB69 cells, as demonstrated by morphologic differentiation, growth inhibition, and enhanced survival in serum-free medium. However, no morphologic, growth, or survival responses to NGF were detected in MYCN-amplified CHP134 and IMR5 TrkA transfectants.


CONCLUSIONS
Thus, transfection of TrkA into MYCN amplified NB cell lines only partly restored the TrkA/NGF signaling pathway, suggesting additional inhibitory effects of MYCN overexpression on TrkA signaling.
Eggert
A
A
Division of Oncology, The Children's Hospital of Philadelphia and Department of Pediatrics, The University of Pennsylvania, Philadelphia, Pennsylvania 19104-4318, USA.
Ho
R
R
Ikegaki
N
N
Liu
X G
XG
Brodeur
G M
GM
D002455:Cell Division; D002470:Cell Survival; D005784:Gene Amplification / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D016259:Genes, myc / Q000235:genetics*; D006801:Humans; D009447:Neuroblastoma / Q000235:genetics*; D010766:Phosphorylation; D012333:RNA, Messenger / Q000096:biosynthesis; D020917:Receptor, trkA / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D020917:Receptor, trkA