title: Ectopic expression of protein-tyrosine kinase Bcr-Abl suppresses tumor necrosis factor (TNF)-induced NF-kappa B activation and IkappaBalpha phosphorylation. Relationship with down-regulation of TNF receptors.
abstract: Bcr-Abl, the product of the protooncogene bcr-abl, is a constitutively active protein-tyrosine kinase that is highly expressed in chronic myelogenous leukemia and in acute myeloid leukemia cells. Because Bcr-Abl is known to provide mitogenic signals through suppression of apoptosis, we investigated the effect of this oncogene product on signaling by tumor necrosis factor (TNF), a proapoptotic cytokine. We used a bcr-abl-deficient human megakaryocytic leukemia cell line MO7E and an isogenic MBA cell line stably transfected with bcr-abl. Electrophoretic mobility shift assay revealed that TNF activated the nuclear transcription factor NF-kappaB in MO7E cells but not in MBA cells. The impaired NF-kappaB activation in Bcr-Abl-expressing cells was not due to absence of the NF-kappaB proteins p65, p50, or p100 or of IkappaBalpha or IkappaBbeta. Okadaic acid-induced NF-kappaB activation was unaffected by Bcr-Abl expression. TNF induced IkappaBalpha phosphorylation and degradation in MO7E cells but not in MBA cells. The suppression of TNF-induced NF-kappaB activation by Bcr-Abl was not restricted to MBA cells, because ectopic expression of Bcr-Abl in human acute myeloid leukemia HL-60 cells also blocked TNF-induced NF-kappaB activation. When examined for the TNF receptors by the radioreceptor assay, flow cytometry, or Western blot analysis, we found that Bcr-Abl expression down-regulated the expression of the TNF receptors. The RNase protection assay and Northern blot analysis revealed the transcriptional down-regulation of the TNF receptor by Bcr-Abl protein. Overall, these results indicate that ectopic expression of Bcr-Abl interferes with the TNF signaling pathway through the down-regulation of TNF receptors.
authors.affiliation: Cytokine Research Laboratory, Department of Bioimmunotherapy, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Asok
authors.initials: A
authors.lastname: Mukhopadhyay
authors.forename: Shishir
authors.initials: S
authors.lastname: Shishodia
authors.forename: Jill
authors.initials: J
authors.lastname: Suttles
authors.forename: Katherine
authors.initials: K
authors.lastname: Brittingham
authors.forename: Betty
authors.initials: B
authors.lastname: Lamothe
authors.forename: Ramdevi
authors.initials: R
authors.lastname: Nimmanapalli
authors.forename: Kapil N
authors.initials: KN
authors.lastname: Bhalla
authors.forename: Bharat B
authors.initials: BB
authors.lastname: Aggarwal
mesh_terms: D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation; D016044:Fusion Proteins, bcr-abl / Q000502:physiology*; D006801:Humans; D020672:I-kappa B Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D016044:Fusion Proteins, bcr-abl; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases