| Research Abstract |
Intravenous inoculation of radiation-induced murine myeloid cells, C2M-A5, into C3H/He mice resulted in the development of myeloid leukemia. However, the leukemic death of the mice was completely suppressed by the subcutaneous injections of G-CSF.This anti-leukemic effect of G-CSF was ascribed to apoptosis of C2M-A5 cells induced by G-CSF.Besides G-CSF,the apoptosis-inducing effect on C2M-A5 cells was observed in GM-CSF and IL-3, but not in Epo, M-CSF,SCF,LIF,EDF,IL-1, IL-4, IL-5, IL-6, IL-7, and IL-11. G-CSF,GM-CSF,and IL-3 seemed to induce apoptosis of C2M-A5 cells independently because the apoptosis-inducing effect of GM-CSF was observed in the presence of both anti-G-CSF antibody and anti-IL-3 anti-body, and because the apoptosis-inducing effect of IL-3 was observed in the presence of both anti-G-CSF antibody and anti-GM-CSF antibody. The induction of apoptosis of C2M-A5 cells was closely related to the activation of c-myc since the activation of c-myc was observed prior to apoptosis by G-CSF.On the other hand, activation of jun, fos, myb, sis, src, and erb-A was not observed. Furthermore, the progression of cell cycle seemed to play an important role in the induction of apoptosis since the accumulation of C2M-A5 cells in G_0/G_1 phase and the reduction of C2M-A5 cells in S phase were observed in the apoptosis.
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