title: An activating mutation in the kit receptor abolishes the stroma requirement for growth of ELM erythroleukemia cells, but does not prevent their differentiation in response to erythropoietin.
abstract: We have previously shown that murine ELM erythroleukemia cells can only be grown in vitro in the presence of a stromal feeder layer, or alternatively stem cell factor (SCF), without which they differentiate. When grown in the presence of SCF, ELM cells can still differentiate in response to erythropoietin (Epo), but growth on stroma prevents this. We previously isolated a stroma-independent ELM variant, ELM-I-1, that is also defective in Epo-induced differentiation. We show here that this variant has an activating mutation in the Kit receptor, converting aspartic acid 814 to histidine. Expression of the mutant receptor in stroma-dependent ELM-D cells causes growth factor-independent proliferation and also gives the cells a selective advantage, in terms of proliferation rate and clonegenicity, compared with ELM-D cells grown in optimal amounts of SCF. Expression of the mutant receptor in ELM-D cells also prevents spontaneous differentiation, but not differentiation induced by Epo. Analysis of mitogenic signaling pathways in these cells shows that the mutant receptor induces constitutive activation of p42/p44 mitogen-activated protein kinases. It also selectively inhibits the expression of p66Shc but not the p46/p52 Shc isoforms (as did treatment of ELM cells with SCF), which is of interest, because p66Shc is known to play an inhibitory role in growth factor signaling.
authors.affiliation: Beatson Institute for Cancer Research, CRC Beatson Laboratories, Glasgow, Scotland.
authors.forename: N R
authors.initials: NR
authors.lastname: Leslie
authors.forename: J
authors.initials: J
authors.lastname: O'Prey
authors.forename: C
authors.initials: C
authors.lastname: Bartholomew
authors.forename: P R
authors.initials: PR
authors.lastname: Harrison
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004921:Erythropoietin / Q000494:pharmacology*; D015870:Gene Expression; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D010766:Phosphorylation; D017354:Point Mutation; D014176:Protein Biosynthesis; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019089:Stem Cell Factor / Q000494:pharmacology; D017154:Stromal Cells / Q000166:cytology*; D015534:Trans-Activators / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D004268:DNA-Binding Proteins; C497426:Fli1 protein, mouse; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019089:Stem Cell Factor; D015534:Trans-Activators; D004921:Erythropoietin; D019009:Proto-Oncogene Proteins c-kit