title: Inhibition of phosphotyrosine phosphatase 1B causes resistance in BCR-ABL-positive leukemia cells to the ABL kinase inhibitor STI571.
abstract: Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of BCR-ABL-mediated transformation in vitro and in vivo. To investigate whether PTP1B modulates the biological effects of the abl kinase inhibitor STI571 in BCR-ABL-positive cells, we transfected Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia cell-derived K562 cells with either wild-type PTP1B (K562/PTP1B), a substrate-trapping dominant-negative mutant PTP1B (K562/D181A), or empty vector (K562/mock). Cells were cultured with or without STI571 and analyzed for its effects on proliferation, differentiation, and apoptosis. In both K562/mock and K562/PTP1B cells, 0.25 to 1 mumol/L STI571 induced dose-dependent growth arrest and apoptosis, as measured by a decrease of cell proliferation and an increase of Annexin V-positive cells and/or of cells in the sub-G(1) apoptotic phase. Western blot analysis showed increased protein levels of activated caspase-3 and caspase-8 and induction of poly(ADP-ribose) polymerase cleavage. Low concentrations of STI571 promoted erythroid differentiation of these cells. Conversely, K562/D181A cells displayed significantly lower PTP1B-specific tyrosine phosphatase activity and were significantly less sensitive to STI571-induced growth arrest, apoptosis, and erythroid differentiation. Pharmacologic inhibition of PTP1B activity in wild-type K562 cells, using bis(N,N-dimethylhydroxamido)hydroxooxovanadate, attenuated STI571-induced apoptosis. Lastly, comparison of the STI571-sensitive Ph+ acute lymphoblastic leukemia cell line SupB15 with a STI571-resistant subline revealed significantly decreased PTP1B activity and enhanced BCR-ABL phosphorylation in the STI571-resistant SupB15 cells. In conclusion, functional PTP1B is involved in STI571-induced growth and cell cycle arrest, apoptosis, and differentiation, and attenuation of PTP1B function may contribute to resistance towards STI571.
authors.affiliation: Division of Hematology, Department of Internal Medicine II, Johann Wolfgang Goethe University, Frankfurt, Germany.
authors.forename: Noriko
authors.initials: N
authors.lastname: Koyama
authors.forename: Steffen
authors.initials: S
authors.lastname: Koschmieder
authors.forename: Sandhya
authors.initials: S
authors.lastname: Tyagi
authors.forename: Ignacio
authors.initials: I
authors.lastname: Portero-Robles
authors.forename: Jörg
authors.initials: J
authors.lastname: Chromic
authors.forename: Silke
authors.initials: S
authors.lastname: Myloch
authors.forename: Heike
authors.initials: H
authors.lastname: Nürnberger
authors.forename: Tanja
authors.initials: T
authors.lastname: Rossmanith
authors.forename: Wolf-Karsten
authors.initials: WK
authors.lastname: Hofmann
authors.forename: Dieter
authors.initials: D
authors.lastname: Hoelzer
authors.forename: Oliver Gerhard
authors.initials: OG
authors.lastname: Ottmann
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D016044:Fusion Proteins, bcr-abl / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D010766:Phosphorylation; D010879:Piperazines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011743:Pyrimidines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014638:Vanadates / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D004791:Enzyme Inhibitors; D010879:Piperazines; D011743:Pyrimidines; C402001:bis(N,N-dimethylhydroxamido)hydroxooxovanadate; D014638:Vanadates; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases