Flotillin-1 regulates oncogenic signaling in neuroblastoma cells by regulating ALK membrane association.

Neuroblastomas harbor mutations in the nonreceptor anaplastic lymphoma kinase (ALK) in 8% to 9% of cases where they serve as oncogenic drivers. Strategies to reduce ALK activity offer clinical interest based on initial findings with ALK kinase inhibitors. In this study, we characterized phosphotyrosine-containing proteins associated with ALK to gain mechanistic insights in this setting. Flotillin-1 (FLOT1), a plasma membrane protein involved in endocytosis, was identified as a binding partner of ALK. RNAi-mediated attenuation of FLOT1 expression in neuroblastoma cells caused ALK dissociation from endosomes along with membrane accumulation of ALK, thereby triggering activation of ALK and downstream effector signals. These features enhanced the malignant properties of neuroblastoma cells in vitro and in vivo. Conversely, oncogenic ALK mutants showed less binding affinity to FLOT1 than wild-type ALK. Clinically, lower expression levels of FLOT1 were documented in highly malignant subgroups of human neuroblastoma specimens. Taken together, our findings suggest that attenuation of FLOT1-ALK binding drives malignant phenotypes of neuroblastoma by activating ALK signaling.
AuthorsArata Tomiyama, Takamasa Uekita, Reiko Kamata, Kazuki Sasaki, Junko Takita, Miki Ohira, Akira Nakagawara, Chifumi Kitanaka, Kentaro Mori, Hideki Yamaguchi, Ryuichi Sakai
JournalCancer research (Cancer Res) Vol. 74 Issue 14 Pg. 3790-801 (Jul 15 2014) ISSN: 1538-7445 [Electronic] United States
PMID24830726 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Copyright©2014 American Association for Cancer Research.
Chemical References
  • Membrane Proteins
  • flotillins
  • Receptor Protein-Tyrosine Kinases
  • anaplastic lymphoma kinase
  • Animals
  • Cell Line, Tumor
  • Cell Membrane (metabolism)
  • Cell Transformation, Neoplastic (genetics, metabolism)
  • Disease Models, Animal
  • Endocytosis
  • Female
  • Gene Expression
  • Heterografts
  • Humans
  • Membrane Proteins (metabolism)
  • Mice
  • Mutation
  • Neuroblastoma (genetics, metabolism, mortality)
  • Phenotype
  • Prognosis
  • Protein Binding
  • Protein Stability
  • Proteolysis
  • Receptor Protein-Tyrosine Kinases (genetics, metabolism)
  • Signal Transduction

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