title: A tripartite complex composed of ETV6-NTRK3, IRS1 and IGF1R is required for ETV6-NTRK3-mediated membrane localization and transformation.
abstract: ETV6-NTRK3 (EN), a chimeric tyrosine kinase generated by t(12;15) translocations, is a dominantly acting oncoprotein in diverse tumor types. We previously showed that insulin-like growth factor 1 receptor (IGF1R) is essential for EN-mediated oncogenesis and that insulin receptor substrate 1 (IRS1) is constitutively tyrosine phosphorylated and bound by EN in transformed cells. Given that IRS1 is also an adapter for IGF1R, we hypothesized that IRS1 might localize EN to IGF1R at the membrane to activate phosphatidylinositol 3-kinase (PI3K)-Akt, which is critical for EN oncogenesis. In this study, we examined EN/IRS1/IGF1R complexes in detail. We find that both IRS1 and kinase active IGF1R are required for EN transformation, that tyrosine phosphorylated IRS1 is present in high molecular weight complexes with EN and IGF1R, and that EN colocalizes with IGF1R at the plasma membrane. Both IGF1R kinase activity and an intact cytoplasmic Y950 residue, the IRS1-docking site of IGF1R, are required, confirming the importance of the IGF1R/IRS1 interaction for EN oncogenesis. The dual specificity IGF1R and insulin receptor (INSR) inhibitor, BMS-536924, blocks EN transformation activity, cell survival and its interaction with IRS proteins, and induces a striking shift of EN proteins to smaller sized molecular complexes. We conclude that a tripartite complex of EN, IRS1 and IGF1R localizes EN to the membrane and that this is essential for EN-mediated transformation. These findings provide an explanation for the observed IGF1R dependency of EN transformation. Blocking IGF1R kinase activity may, therefore, provide a tractable therapeutic strategy for the many tumor types driven by the EN oncoprotein.
authors.affiliation: Department of Molecular Oncology, BC Cancer Research Centre, Vancouver, British Columbia, Canada.
authors.forename: C E
authors.initials: CE
authors.lastname: Tognon
authors.forename: M J
authors.initials: MJ
authors.lastname: Martin
authors.forename: A
authors.initials: A
authors.lastname: Moradian
authors.forename: G
authors.initials: G
authors.lastname: Trigo
authors.forename: B
authors.initials: B
authors.lastname: Rotblat
authors.forename: S-W G
authors.initials: SW
authors.lastname: Cheng
authors.forename: M
authors.initials: M
authors.lastname: Pollard
authors.forename: E
authors.initials: E
authors.lastname: Uy
authors.forename: C
authors.initials: C
authors.lastname: Chow
authors.forename: J M
authors.initials: JM
authors.lastname: Carboni
authors.forename: M M
authors.initials: MM
authors.lastname: Gottardis
authors.forename: M
authors.initials: M
authors.lastname: Pollak
authors.forename: G B
authors.initials: GB
authors.lastname: Morin
authors.forename: P H B
authors.initials: PH
authors.lastname: Sorensen
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic; D055504:Insulin Receptor Substrate Proteins / Q000502:physiology*; D007377:Interleukin-3 / Q000494:pharmacology; D051379:Mice; D015514:Oncogene Proteins, Fusion / Q000502:physiology*; D010766:Phosphorylation; D017526:Receptor, IGF Type 1 / Q000502:physiology*; D020812:Receptor, trkC; D000097764:ETS Translocation Variant 6 Protein
chemical_list: D055504:Insulin Receptor Substrate Proteins; D007377:Interleukin-3; D015514:Oncogene Proteins, Fusion; D017526:Receptor, IGF Type 1; C526167:ETV6-NTRK3 fusion protein, mouse; D020812:Receptor, trkC; D000097764:ETS Translocation Variant 6 Protein; C526295:Irs1 protein, mouse; C491531:Irs4 protein, mouse