Induction of apoptosis in myeloid leukaemic cells by ribozymes targeted against AML1/MTG8.
The translocation (8;21)(q22;q22) is a karyotypic abnormality detected in acute myeloid leukaemia (AML) M2 and results in the formation of the chimeric fusion gene AML1/MTG8. We previously reported that two hammerhead ribozymes against AML1/MTG8 cleave this fusion transcript and also inhibit the proliferation of myeloid leukaemia cell line Kasumi-1 which possesses t(8;21)(q22;q22). In this study, we investigated the mechanisms of inhibition of proliferation in myeloid leukaemic cells with t(8;21)(q22;q22) by ribozymes. These ribozymes specifically inhibited the growth of Kasumi-1 cells, but did not affect the leukaemic cells without t(8;21)(q22;q22). We observed the morphological changes including chromatin condensation, fragmentation and the formation of apoptotic bodies in Kasumi-1 cells incubated with ribozymes for 7 days. In addition, DNA ladder formation was also detected after incubation with ribozymes which suggested the induction of apoptosis in Kasumi-1 cells by the AML1/MTG8 ribozymes. However, the ribozymes did not induce the expression of CD11b and CD14 antigens in Kasumi-1 cells. The above data suggest that these ribozymes therefore inhibit the growth of myeloid leukaemic cells with t(8;21)(q22;q22) by the induction of apoptosis, but not differentiation. We conclude therefore that the ribozymes targeted against AML1/MTG8 may have therapeutic potential for patients with AML carrying t(8;21)(q22;q22) while, in addition, the product of the chimeric gene is responsible for the pathogenesis of myeloid leukaemia.
Matsushita
H
H
Division of Haematology, Keio University School of Medicine, Tokyo, Japan.
Kizaki
M
M
Kobayashi
H
H
Muto
A
A
Ikeda
Y
Y
D017209:Apoptosis / Q000235:genetics; D002454:Cell Differentiation; D002455:Cell Division; D002891:Chromosomes, Human, Pair 21; D002898:Chromosomes, Human, Pair 8; D050676:Core Binding Factor Alpha 2 Subunit; D053938:DNA Fragmentation; D004273:DNA, Neoplasm; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000503:physiopathology*; D009363:Neoplasm Proteins / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion; D016337:RNA, Catalytic / Q000378:metabolism*; D000075142:RUNX1 Translocation Partner 1 Protein; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured
C107844:AML1-ETO fusion protein, human; D050676:Core Binding Factor Alpha 2 Subunit; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; D016337:RNA, Catalytic; D000075142:RUNX1 Translocation Partner 1 Protein; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors