title: Growth-promoting effects of insulin-like growth factor-1 (IGF-1) on hematopoietic cells: overexpression of introduced IGF-1 receptor abrogates interleukin-3 dependency of murine factor-dependent cells by a ligand-dependent mechanism.
abstract: Although insulin-like growth factor (IGF-1) stimulated 3H-thymidine incorporation upon addition to the interleukin-3 (IL-3)-dependent cell line FDC-P1, IGF-1 did not relieve IL-3 dependency for growth. To further examine the effects of IGF-1 on hematopoietic cells, FDC-P1 cells were infected with a retroviral construct (LISN) containing the human IGF-1 receptor (hIGF-1R) and neo genes. IL-3-independent cells were readily isolated after LISN infection when either IGF-1 or supraphysiologic concentrations of insulin were included in the culture medium. These cells were transformed to IL-3 independence by a ligand-dependent mechanism because their growth was dependent on the presence of either IGF-1 or insulin and growth factors capable of supporting autocrine growth were not detected. Furthermore, a monoclonal antibody (MoAb) directed against the human IGF-1R (alpha IR-3) inhibited IGF-1 but not IL-3-induced proliferation and these cells contained 20- to 200-fold more IGF-1 receptors than uninfected FDC-P1 cells. In contrast, when LISN-infected cells were plated in medium without exogenously supplied IGF-1 or insulin, factor-independent cells were rarely isolated. Growth of these cells was also inhibited by the alpha IR-3 MoAb and they expressed 100- to 400-fold more IGF-1 receptors than uninfected FDC-P1 cells. The endogenous IGF-1 and/or insulin present in the calf serum may have enabled their growth because these cells, unlike the parental cells, would proliferate in serum-free defined media and their growth was again inhibited by the alpha IR-3 MoAb. These results demonstrate that IGF-1 can replace IL-3 for growth when FDC-P1 cells overexpress the IGF-1R. Given the fairly ubiquitous expression of the IGF-1 receptor, these and additional experiments might help to determine whether increased expression of endogenous receptors by cells can lead to leukemogenesis and tumorigenesis. Moreover, hIGF-1R-infected cells will be useful in investigating the mechanisms of IGF1-mediated signal transduction because they are now known to proliferate in response to IGF-1.
authors.affiliation: Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, NC 27858.
authors.forename: J A
authors.initials: JA
authors.lastname: McCubrey
authors.forename: L S
authors.initials: LS
authors.lastname: Steelman
authors.forename: M W
authors.initials: MW
authors.lastname: Mayo
authors.forename: P A
authors.initials: PA
authors.lastname: Algate
authors.forename: R A
authors.initials: RA
authors.lastname: Dellow
authors.forename: M
authors.initials: M
authors.lastname: Kaleko
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004357:Drug Synergism; D015870:Gene Expression; D005822:Genetic Vectors; D006133:Growth Substances / Q000096:biosynthesis; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007377:Interleukin-3 / Q000494:pharmacology*; D009955:Ornithine Decarboxylase / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017451:Receptors, Somatomedin; D011994:Recombinant Proteins / Q000494:pharmacology; D012190:Retroviridae / Q000235:genetics; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D006133:Growth Substances; D007328:Insulin; D007377:Interleukin-3; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D004247:DNA; D009955:Ornithine Decarboxylase