Primary leukemia cells can respond very differently to cytokines such as G-CSF and GM-CSF, demonstrating marked increases in colony-forming ability to one but not the other (

Park et al, Blood 1989; 74: 56–65
). To examine if such differences might correlate with underlying molecular abnormalities, we examined the growth and survival response of hematopoietic cells containing abnormal RUNX1 variants (a frequent occurrence in leukemia and myelodysplastic syndrome) to treatment with G-CSF and GM-CSF. In the RUNX1-ETO containing cell-line Kasumi-1, GM-CSF decreased colony forming ability whereas G-CSF preserved or increased it. The 32Dcl3 murine myelomonocytic cell-line terminally differentiates in response to G-CSF or mGM-CSF. We transduced 32Dcl3 with RUNX1-ETO or Empty Vector: G-CSF promoted the growth and survival of 32D RUNX1-ETO but caused 32D Empty Vector to terminally differentiate and die. In contrast, 32D RUNX1-ETO cultured in mGM-CSF demonstrated accelerated terminal differentiation and death compared to 32D Empty Vector. Many of the RUNX1 variants seen in leukemia and myelodysplastic syndrome, including RUNX1-ETO, lack the RUNX1 C-terminal transcription regulating domain (TRD). In human CD34+ hematopoietic cells transduced with RUNX1 with TRD deleted (CD34 RUNX1noTRD), colony forming ability was retained even after >40 days of culture in IMDM 10% FBS, SCF 10ng/ml, IL-3 30ng/ml, G-CSF 100ng/ml (CD34 Empty Vector lost colony forming ability after 14 days). However, culture in media supplemented with 100ng/ml GM-CSF instead of G-CSF significantly impaired colony forming ability of CD34 RUNX1noTRD compared to CD34 Empty Vector. In conclusion, RUNX1 variants seen in acute myeloid leukemia and myelodysplastic syndrome promote growth and survival in G-CSF but accelerate differentiation and death in response to GM-CSF. The molecular basis for this effect appears to relate to the presence or absence of the RUNX1 C-terminal transcription regulating domain. These findings may have clinical relevance.

Topics:
granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, recombinant granulocyte colony stimulating factor, recombinant granulocyte-macrophage colony-stimulating factors, cd34 antigens, leukemia, myelodysplastic syndrome, colony-stimulating factors, cytokine, death

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2005, The American Society of Hematology
2005
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