Antisense Oligodeoxyribonucleotide against the MLL-LTG19 Chimeric Transcript Inhibits Cell Growth and Induces Apoptosis in Cells of an Infantile Leukemia Cell Line Carrying the t(ll;19) Chromosomal Translocation1

To clarify the role of the multiple lineage leukemia gene-leukemia translocation gene of chromosome 19 (MLL-LTG19) protein in leukemogenesis, we synthesized antisense Oligodeoxyribonucleotide (ODN) against the fused region of the MLL-LTG19 chimi-rie transcript and treated KOCL33 cells carrying the t(ll;19) translocation with antisense ODN. The antisense ODN inhibited cell growth and induced apoptosis in KOCL33 cells but not in Daudi cells, which have no nil:!'»). The levels of MLL-LTG19 mRNA and MLL-LTG19 protein in KOCL33 cells treated with antisense ODN were shown to decrease with time by reverse transcription-PCR and Western blot analysis. These results suggest that the MLL-LTG19 fusion protein contributes to cell proliferation and malig nant transformation in infantile acute leukemia cells carrying the t(ll;19) translocation.