title: Inhibition of proliferation and induction of apoptosis in juvenile myelomonocytic leukemic cells by the granulocyte-macrophage colony-stimulating factor analogue E21R.
abstract: Juvenile myelomonocytic leukemia (JMML) is a malignancy that almost inevitably leads to death before adulthood. Chemotherapy has given disappointing results and a substantial number of patients relapse after bone marrow transplantation. A salient feature of this disease is that the JMML cells produce granulocyte-macrophage colony-stimulating factor (GM-CSF) spontaneously and survive and proliferate without exogeneous GM-CSF. Furthermore, JMML cells are hypersensitive to GM-CSF with addition of this cytokine leading to enhanced proliferation. We have recently generated a human GM-CSF analogue, E21R, that acts as a complete and selective GM-CSF receptor antagonist. We have now tested this molecule as a potential new agent to control the leukemic cell load in JMML with particular emphasis on its role in JMML cell survival. We found that E21R inhibited the spontaneous growth of JMML cells in vitro and caused their apoptosis in a dose- and time-dependent manner in seven of seven cases. In contrast, neither a neutralizing anti-GM-CSF monoclonal antibody (MoAb) nor a selective interleukin-1 (IL-1) receptor antagonist affected JMML cell survival. Furthermore, the apoptotic effect of E21R was seen even in the presence of interleukin-1 beta and tumor necrosis factor-alpha, which have also been implicated in the pathogenesis of JMML. The inhibitory effects of E21R on JMML cell growth and viability offer a novel approach to therapy in this lethal childhood leukemia.
authors.affiliation: Division of Human Immunology, Hanson Centre for Cancer Research, IMVS, Adelaide, Australia.
authors.forename: P O
authors.initials: PO
authors.lastname: Iversen
authors.forename: R L
authors.initials: RL
authors.lastname: Rodwell
authors.forename: L
authors.initials: L
authors.lastname: Pitcher
authors.forename: K M
authors.initials: KM
authors.lastname: Taylor
authors.forename: A F
authors.initials: AF
authors.lastname: Lopez
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002675:Child, Preschool; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000276:immunology / Q000494:pharmacology; D006801:Humans; D007223:Infant; D007375:Interleukin-1 / Q000096:biosynthesis; D015477:Leukemia, Myelomonocytic, Chronic / Q000473:pathology*; D008297:Male; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors*; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors*; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D000911:Antibodies, Monoclonal; D007375:Interleukin-1; D009363:Neoplasm Proteins; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; C101659:granulocyte-macrophage colony-stimulating factor, Arg(21)-; D016178:Granulocyte-Macrophage Colony-Stimulating Factor