title: SHP-2 phosphatase is required for hematopoietic cell transformation by Bcr-Abl.
abstract: SHP-2 phosphatase forms a stable protein complex with and is heavily tyrosine-phosphorylated by the oncogenic tyrosine kinase Bcr-Abl. However, the role of SHP-2 in Bcr-Abl-mediated leukemogenesis is unclear. In the present report, we provide evidence that SHP-2 is required for hematopoietic cell transformation by Bcr-Abl. In vitro biological effects of Bcr-Abl transduction were diminished in SHP-2Delta/Delta hematopoietic cells, and the leukemic potential of Bcr-Abl-transduced SHP-2Delta/Delta cells in recipient animals was compromised. Further analyses showed that Bcr-Abl protein (p210) was degraded, and its oncogenic signaling was greatly decreased in SHP-2Delta/Delta cells. Treatment with proteasome inhibitors or reintroduction of SHP-2 restored p210 level in Bcr-Abl-transduced SHP-2Delta/Delta cells. Subsequent investigation revealed that SHP-2 interacted with heat shock protein 90, an important chaperone protein protecting p210 from proteasome-mediated degradation. The role of SHP-2 in the stability of p210 is independent of its catalytic activity. Blockade of SHP-2 expression in p210-expressing cells by antisense or small-interfering RNA approaches decreased p210 level, causing cell death. Inhibition of SHP-2 enzymatic activity by overexpression of catalytically inactive SHP-2 mutant did not destabilize p210 but enhanced serum starvation-induced apoptosis, suggesting that SHP-2 also plays an important role in downstream signaling of p210 kinase. These studies identified a novel function of SHP-2 and suggest that SHP-2 might be a useful target for controlling Bcr-Abl-positive leukemias.
authors.affiliation: Department of Medicine, Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Wen-Mei
authors.initials: WM
authors.lastname: Yu
authors.forename: Hanako
authors.initials: H
authors.lastname: Daino
authors.forename: Hal E
authors.initials: HE
authors.lastname: Broxmeyer
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Druker
authors.forename: Cheng-Kui
authors.initials: CK
authors.lastname: Qu
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000378:metabolism*; D018014:Gene Transfer Techniques; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000378:metabolism* / Q000473:pathology; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D016376:Oligonucleotides, Antisense; D034741:RNA, Small Interfering; D016044:Fusion Proteins, bcr-abl; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse