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.
Authors' Affiliations: Division of Metastasis and Invasion Signaling, National Cancer Center Research Institute; Department of Neurosurgery, National Defense Medical College, Saitama;
Arata
A
Tomiyama
Authors' Affiliations: Division of Metastasis and Invasion Signaling, National Cancer Center Research Institute; Department of Applied Chemistry, National Defense Academy, Kanagawa;
Takamasa
T
Uekita
Authors' Affiliations: Division of Metastasis and Invasion Signaling, National Cancer Center Research Institute;
Reiko
R
Kamata
Department of Molecular Pharmacology, National Cerebral and Cardiovascular Center Research Institute, Osaka;
Kazuki
K
Sasaki
Department of Cell Therapy and Transplantation Medicine, Graduate School of medicine, The University of Tokyo, Tokyo;
Junko
J
Takita
Divisions of Cancer Genomics and.
Miki
M
Ohira
Biochemistry and Innovative Cancer, Chiba Cancer Center Research Institute, Chiba; and.
Akira
A
Nakagawara
Department of Molecular Cancer Science, Yamagata University School of Medicine, Yamagata, Japan.
Chifumi
C
Kitanaka
Department of Neurosurgery, National Defense Medical College, Saitama;
Kentaro
K
Mori
Authors' Affiliations: Division of Metastasis and Invasion Signaling, National Cancer Center Research Institute;
Hideki
H
Yamaguchi
Authors' Affiliations: Division of Metastasis and Invasion Signaling, National Cancer Center Research Institute; rsakai@ncc.go.jp.
Ryuichi
R
Sakai
D000077548:Anaplastic Lymphoma Kinase; D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004705:Endocytosis; D005260:Female; D015870:Gene Expression; D064593:Heterografts; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D010641:Phenotype; D011379:Prognosis; D011485:Protein Binding; D055550:Protein Stability; D059748:Proteolysis; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D008565:Membrane Proteins; C106354:flotillins; C000626173:ALK protein, human; C000626174:Alk protein, mouse; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases