title: Fusion tyrosine kinase NPM-ALK Deregulates MSH2 and suppresses DNA mismatch repair function novel insights into a potent oncoprotein.
abstract: The fusion tyrosine kinase NPM-ALK is central to the pathogenesis of ALK-positive anaplastic large cell lymphoma (ALK(+)ALCL). We recently identified that MSH2, a key DNA mismatch repair (MMR) protein integral to the suppression of tumorigenesis, is an NPM-ALK-interacting protein. In this study, we found in vitro evidence that enforced expression of NPM-ALK in HEK293 cells suppressed MMR function. Correlating with these findings, six of nine ALK(+)ALCL tumors displayed evidence of microsatellite instability, as opposed to none of the eight normal DNA control samples (P = 0.007, Student's t-test). Using co-immunoprecipitation, we found that increasing levels of NPM-ALK expression in HEK293 cells resulted in decreased levels of MSH6 bound to MSH2, whereas MSH2·NPM-ALK binding was increased. The NPM-ALK·MSH2 interaction was dependent on the activation/autophosphorylation of NPM-ALK, and the Y191 residue of NPM-ALK was a crucial site for this interaction and NPM-ALK-mediated MMR suppression. MSH2 was found to be tyrosine phosphorylated in the presence of NPM-ALK. Finally, NPM-ALK impeded the expected DNA damage-induced translocation of MSH2 out of the cytoplasm. To conclude, our data support a model in which the suppression of MMR by NPM-ALK is attributed to its ability to interfere with normal MSH2 biochemistry and function.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Leah C
authors.initials: LC
authors.lastname: Young
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Bone
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Wu
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Adam
authors.forename: Samar
authors.initials: S
authors.lastname: Hegazy
authors.forename: Pascal
authors.initials: P
authors.lastname: Gelebart
authors.forename: Jelena
authors.initials: J
authors.lastname: Holovati
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.forename: Susan E
authors.initials: SE
authors.lastname: Andrew
authors.forename: Raymond
authors.initials: R
authors.lastname: Lai
mesh_terms: D003593:Cytoplasm / Q000378:metabolism; D004249:DNA Damage; D053843:DNA Mismatch Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D017728:Lymphoma, Large-Cell, Anaplastic / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D053842:Microsatellite Instability; D051718:MutS Homolog 2 Protein / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D055503:Protein Multimerization; D021381:Protein Transport; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D014443:Tyrosine; C107023:p80(NPM-ALK) protein; D011505:Protein-Tyrosine Kinases; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein