The Two Hit Model Of Leukemogenesis: The Role Of Coexpression Of AML1-ETO And IASPPsv In Malignant Hematopoiesis

Cell proliferation and differentiation are strictly regulated by intrinsic and extrinsic signals. Uncontrolled proliferation and impaired differentiation of hematopoietic cells lead to leukemogenesis. According to the two hit hypothesis, most acute leukemias are the consequence of a collaboration of several types of mutations. The AML1-ETO rearrangement t(8;21)(q22;q22) has been reported in acute myeloid leukemia (AML) subtype M2. As an inhibitor of p53-induced apoptosis, iASPP is a novel oncogene.Objective:To investigate the role and mechanism of coexpressed AML1-ETO and iASPPsv in triggering the development of aggressive leukemia.Methods:1) Bone marrow mononuclear cells (BMMNCs) from iASPPsv transgenic C57 mice were infected with the lentiviral vector pCDH expressing AML1-ETO protein and a green fluorescent protein (GFP).2) BMMNCs from AML1-ETO transduced transgenic C57 mice were plated in methylcellulose medium (M3434). BMMNCs infected with the vector expressing GFP only was used as a control.3) BMMNCs from AML1-ETO transduced transgenic C57 mice were transplanted into lethally irradiated mice, the development of leukemia in these mice were observed.4)The expression of AML1-ETO in BMCs was detected by RT-PCR.Results:1)The gene transduction efficiencies, which were assessed by GFP expression in the BMMNCs, were 33.6% to 88.95%.2)Coexpression of AML1-ETO and iASPPsv enhances the colony-forming activity of BMMNCs and inhibits their differentiation at more immature stages.3)The RT-PCR results showed that AML1-ETO mRNA expressed only in AML1-ETO transduced BMMNCs.4)The development of leukemia in the mice coexpressed the iASPPsv and AML1-ETO was not observed yet.Conclusion:Coexpression of AML1-ETO and iASPPsv exhibited inhibition of BMMNCs at more immature stage and higher in vitro colony-forming ability compared with the BMCs expressing GFP only.