title: Global phosphoproteomics reveals crosstalk between Bcr-Abl and negative feedback mechanisms controlling Src signaling.
abstract: In subtypes and late stages of leukemias driven by the tyrosine kinase fusion protein Bcr-Abl, signaling by the Src family kinases (SFKs) critically contributes to the leukemic phenotype. We performed global tyrosine phosphoprofiling by quantitative mass spectrometry of Bcr-Abl-transformed cells in which the activities of the SFKs were perturbed to build a detailed context-dependent network of cancer signaling. Perturbation of the SFKs Lyn and Hck with genetics or inhibitors revealed Bcr-Abl downstream phosphorylation events either mediated by or independent of SFKs. We identified multiple negative feedback mechanisms within the network of signaling events affected by Bcr-Abl and SFKs and found that Bcr-Abl attenuated these inhibitory mechanisms. The C-terminal Src kinase (Csk)-binding protein Pag1 (also known as Cbp) and the tyrosine phosphatase Ptpn18 both mediated negative feedback to SFKs. We observed Bcr-Abl-mediated phosphorylation of the phosphatase Shp2 (Ptpn11), and this may contribute to the suppression of these negative feedback mechanisms to promote Bcr-Abl-activated SFK signaling. Csk and a kinase-deficient Csk mutant both produced similar globally repressive signaling consequences, suggesting a critical role for the adaptor protein function of Csk in its inhibition of Bcr-Abl and SFK signaling. The identified Bcr-Abl-activated SFK regulatory mechanisms are candidates for dysregulation during leukemia progression and acquisition of SFK-mediated drug resistance.
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Liudmilla
authors: L
authors: Rubbi
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Björn
authors: B
authors: Titz
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Lauren
authors: L
authors: Brown
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Erica
authors: E
authors: Galvan
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Evangelia
authors: E
authors: Komisopoulou
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Sharon S
authors: SS
authors: Chen
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Tracey
authors: T
authors: Low
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.
authors: Martik
authors: M
authors: Tahmasian
authors: David Geffen School of Medicine, Division of Rheumatology, University of California, Los Angeles CA 90095, USA.
authors: Brian
authors: B
authors: Skaggs
authors: Department of Laboratory Medicine, University of California, San Francisco CA 94143, USA.
authors: Markus
authors: M
authors: Müschen
authors: Institute for Genomics and Proteomics; Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles CA 90095, USA.|California NanoSystems Institute, University of California, Los Angeles CA 90095, USA.
authors: Matteo
authors: M
authors: Pellegrini
authors: Crump Institute for Molecular Imaging; Institute for Molecular Medicine; Jonsson Comprehensive Cancer Center, California NanoSystems Institute, David Geffen School of Medicine, Department of Molecular & Medical Pharmacology, University of California, Los Angeles CA 90095, USA.|California NanoSystems Institute, University of California, Los Angeles CA 90095, USA.
authors: Thomas G
authors: TG
authors: Graeber
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000081247:CSK Tyrosine-Protein Kinase; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007938:Leukemia / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D008565:Membrane Proteins; C498710:PAG1 protein, human; D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D016044:Fusion Proteins, bcr-abl; D019061:src-Family Kinases; C000631346:CSK protein, human; C422224:PTPN18 protein, human; D054558:Protein Tyrosine Phosphatases, Non-Receptor