Notch1 expression predicts an unfavorable prognosis and serves as a therapeutic target of patients with neuroblastoma.
OBJECTIVE
Notch signaling has been implicated to play a critical role in the tumorigenesis of neuroblastoma (NB) and can modulate calreticulin (CRT) expression that strongly correlates with tumor differentiation and favorable prognosis of NB. We thus sought to determine how Notch regulates CRT expression and affects NB tumor behavior.


METHODS
The Notch-dependent regulation of CRT expression in cultured NB cells was analyzed by confocal microscopy and Western blotting. Notch1 protein expression in 85 NB tumors was examined by immunohistochemistry and correlated with the clinicopathologic/biological characters of NB patients. The progression of NB tumors in response to attenuated Notch signaling was examined by using a xenograft mouse model.


RESULTS
We showed that CRT is essential for the neuronal differentiation of NB cells elicited by inhibition of Notch signaling. This effect was mediated by a c-Jun-NH(2)-kinase-dependent pathway. Furthermore, NB tumors with elevated Notch1 protein expression were strongly correlated with advanced tumor stages, MYCN amplification, an undifferentiated histology, as well as a low CRT expression level. Most importantly, the opposing effect between Notch1 and CRT could reciprocally affect the survival of NB patients. The administration of a gamma-secretase inhibitor into a xenograft mouse model of NB significantly suppressed the tumor progression.


CONCLUSIONS
Our findings provide the first evidence that a c-Jun-NH(2)-kinase-CRT-dependent pathway is essential for the neuronal differentiation elicited by Notch signaling blockade and that Notch1 and CRT can synergistically predict the clinical outcomes of NB patients. The present data suggest that Notch signaling could be a therapeutic target for NB.
Chang
Hsiu-Hao
HH
Department of Pediatrics, National Taiwan University Hospital, Taiwan.
Lee
Hsinyu
H
Hu
Ming-Kuan
MK
Tsao
Po-Nien
PN
Juan
Hsueh-Fen
HF
Huang
Min-Chuan
MC
Shih
Yu-Yin
YY
Wang
Bo-Jeng
BJ
Jeng
Yung-Ming
YM
Chang
Christina Ling
CL
Huang
Shiu-Feng
SF
Tsay
Yeou-Guang
YG
Hsieh
Fon-Jou
FJ
Lin
Kai-Hsin
KH
Hsu
Wen-Ming
WM
Liao
Yung-Feng
YF
D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D015153:Blotting, Western; D037282:Calreticulin / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D053208:Kaplan-Meier Estimate; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D009842:Oligopeptides / Q000494:pharmacology; D011237:Predictive Value of Tests; D011379:Prognosis; D034622:RNA Interference; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
D000873:Anthracenes; D037282:Calreticulin; D009842:Oligopeptides; D051881:Receptor, Notch1; C523462:benzyloxycarbonyl-leucyl-leucyl-norleucinal; C432165:pyrazolanthrone; D048031:JNK Mitogen-Activated Protein Kinases; D053829:Amyloid Precursor Protein Secretases