title: Signaling of ERBB receptor tyrosine kinases promotes neuroblastoma growth in vitro and in vivo.
abstract: BACKGROUND
  ERBB receptor tyrosine kinases can mediate proliferation, migration, adhesion, differentiation, and survival in many types of cells and play critical roles in many malignancies. Recent reports suggest a role for EGFR signaling in proliferation and survival of neuroblastoma, a common form of pediatric cancer that often has an extremely poor outcome.
  
  
  METHODS
  The authors examined ERBB family expression in neuroblastoma cell lines and patient samples by flow cytometry, western blot, and quantitative real time polymerase chain reaction (Q-PCR). Response to ERBB inhibition was assessed in vitro by cell-cycle analysis and western blot and in vivo by serial tumor-size measurements.
  
  
  RESULTS
  A panel of neuroblastoma cell lines and primary patient tumors expressed EGFR, HER-3, and HER-4, with HER-2 in some tumors. HER-4 mRNA was expressed predominantly in cleavable isoforms. Whereas EGFR inhibition with erlotinib and pan-ERBB inhibition with CI-1033 inhibited EGF-induced phosphorylation of EGFR, AKT, and ERK1/2, only CI-1033 induced growth inhibition and dose-dependent apoptosis in vitro. Both CI-1033 and erlotinib treatment of neuroblastoma xenograft tumors resulted in decreased tumor growth in vivo, although CI-1033 was more effective. In vivo expression of EGFR was observed predominantly in vascular endothelial cells.
  
  
  CONCLUSIONS
  Pan-ERBB inhibition is required for ERBB-related neuroblastoma apoptosis in vitro, although EGFR contributes indirectly to tumor growth in vivo. Inhibition of EGFR in endothelial cells may be an important aspect of erlotinib's impact on neuroblastoma growth in vivo. Our results suggest that non-EGFR ERBB family members contribute directly to neuroblastoma growth and survival, and pan-ERBB inhibition represents a potential therapeutic target for treating neuroblastoma.
authors.affiliation: Department of Pediatrics Research, Children's Cancer Hospital, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Kristen N
authors.initials: KN
authors.lastname: Richards
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Zweidler-McKay
authors.forename: Nadine
authors.initials: N
authors.lastname: Van Roy
authors.forename: Frank
authors.initials: F
authors.lastname: Speleman
authors.forename: Jesus
authors.initials: J
authors.lastname: Trevino
authors.forename: Peter E
authors.initials: PE
authors.lastname: Zage
authors.forename: Dennis P M
authors.initials: DP
authors.lastname: Hughes
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009025:Morpholines / Q000494:pharmacology; D009368:Neoplasm Transplantation; D009447:Neuroblastoma / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology*; D015398:Signal Transduction
chemical_list: D009025:Morpholines; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; C420268:Canertinib; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; D066246:ErbB Receptors