Mutation-independent anaplastic lymphoma kinase overexpression in poor prognosis neuroblastoma patients.
Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase predominantly expressed in the developing nervous system. Recently, mutated ALK has been identified as a major oncogene associated with familial and sporadic neuroblastomas (NBL). Yet, a direct correlation between endogenous expression level of the ALK protein, oncogenic potential, and clinical outcome has not been established. We investigated ALK genetic mutations, protein expression/phosphorylation, and functional inhibition both in NBL-derived cell lines and in 34 localized and 48 advanced/metastatic NBL patients. ALK constitutive phosphorylation/activation was observed in high-ALK expressing cells, harboring either a mutated or a wild-type receptor. No activation was found in cell lines with low expression of wild-type ALK. After 72 hours of treatments, small molecule ALK inhibitor CEP-14083 (60 nmol/L) induced growth arrest and cell death in NBL cells overexpressing wild-type (viability: ALK(high) 12.8%, ALK(low) 73%, P = 0.0035; cell death: ALK(high) 56.4%, ALK(low) 16.2%, P = 0.0001) or mutated ALK. ALK protein expression was significantly up-regulated in advanced/metastatic compared with localized NBLs (ALK overexpressing patients: stage 1-2, 23.5%; stage 3-4, 77%; P < 0.0001). Interestingly, protein levels did not always correlate with ALK genetic alterations and/or mRNA abundance. Both mutated and wild-type ALK receptor can exert oncogenic activity in NBL cells. However, wild-type ALK receptor requires a critical threshold of expression to achieve oncogenic activation. Overexpression of either mutated or wild-type ALK defines poor prognosis patients. Alternative mechanisms other than direct mutations and/or gene amplification regulate the ALK level of expression in NBL cells. Wild-type ALK is a potential therapeutic target for advanced/metastatic NBLs.
Passoni
Lorena
L
Pediatric Oncology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy. lorena.passoni@istitutotumori.mi.it
Longo
Luca
L
Collini
Paola
P
Coluccia
Addolorata Maria Luce
AM
Bozzi
Fabio
F
Podda
Marta
M
Gregorio
Andrea
A
Gambini
Claudio
C
Garaventa
Alberto
A
Pistoia
Vito
V
Del Grosso
Federica
F
Tonini
Gian Paolo
GP
Cheng
Mangeng
M
Gambacorti-Passerini
Carlo
C
Anichini
Andrea
A
Fossati-Bellani
Franca
F
Di Nicola
Massimo
M
Luksch
Roberto
R
D000077548:Anaplastic Lymphoma Kinase; D002227:Carbazoles / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D018450:Disease Progression; D015536:Down-Regulation; D004789:Enzyme Activation; D018095:Germ-Line Mutation; D006801:Humans; D007150:Immunohistochemistry; D009447:Neuroblastoma / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D010671:Phenylurea Compounds / Q000494:pharmacology; D010766:Phosphorylation; D011379:Prognosis; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases
C540057:CEP 14083; D002227:Carbazoles; D010671:Phenylurea Compounds; D047428:Protein Kinase Inhibitors; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases