Regulation of transcription factors NF kappa B and AP-1 following tumour necrosis factor-alpha treatment of cells from chronic B cell leukaemia patients.
Malignant B lymphocytes from patients with B-chronic lymphocytic leukaemia (B-CLL) or hairy cell leukemia (HCL) are refractory in vitro to mitogenic stimulation by several agents which trigger proliferation of normal B cells. Tumour necrosis factor (TNF) is a growth factor for these malignant cells, although the proliferative response is usually small. TNF regulates some of its cellular responses via induction of the transcription factors NF kappa B and AP-1 (jun/fos). The induction of NF kappa B by TNF is mediated via a novel signalling pathway involving the generation of reactive oxidative intermediates. Induction of jun and fos proteins (polypeptide components of AP-1) are mediated via pathways involving protein kinase C and the protein kinase encoded by the raf proto-oncogene. Here we have used an electrophoretic mobility shift assay to show that TNF induced NF kappa B in malignant cells isolated from 3/3 HCL and 15/15 B-CLL patients. By contrast, phorbol myristate acetate (PMA), a direct activator of protein kinase C, failed to activate this transcription factor in 1/1 HCL and 5/5 B-CLL isolates. The induction of jun and fos proteins (as detected by Western blot analysis) showed greater heterogeneity. Nuclear jun was induced by TNF in 5/12 chronic B cell leukaemia isolates. PMA induced this protein in 4/5 samples. Nuclear fos was induced by TNF in only 2/12 isolates and by PMA in 2/5. The data suggest that the pathways for the activation of jun and fos by TNF are defective in some B-CLL and HCL cells and that these defects may be heterogeneous. The induction of AP-1 is crucial in securing the mitogenic response to TNF. It is therefore plausible that these lesions may contribute to the refractory nature of B-CLL and HCL cells to proliferative stimuli in vitro.
Jabbar
S A
SA
Department of Haematology, Royal Free Hospital School of Medicine, London.
Hoffbrand
A V
AV
Gitendra Wickremasinghe
R
R
D001402:B-Lymphocytes / Q000737:chemistry; D001483:Base Sequence; D015153:Blotting, Western; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D006801:Humans; D007943:Leukemia, Hairy Cell / Q000235:genetics / Q000378:metabolism*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000097:blood / Q000187:drug effects*; D009363:Neoplasm Proteins / Q000187:drug effects; D009841:Oligonucleotides / Q000737:chemistry; D000090063:Proto-Oncogene Mas; D016755:Proto-Oncogene Proteins c-jun / Q000097:blood / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
C000715470:MAS1 protein, human; D016328:NF-kappa B; D009363:Neoplasm Proteins; D009841:Oligonucleotides; D000090063:Proto-Oncogene Mas; D016755:Proto-Oncogene Proteins c-jun; D014409:Tumor Necrosis Factor-alpha