SPECIFIC ANTISENSE OLIGOMER ANTI BCR-ABL JUNCTIONS IN CHRONIC MYELOID-LEUKEMIA - A CELL-CYCLE ANALYSIS AND CFU-GM STUDY

Antisense oligonucleotides were used to determine the role of the BCR- ABL gene in the proliferation of chronic myeloid leukaemia (CML) clono genic cells. Peripheral blood Philadelphia chromosome positive cells w ere obtained from eight CML patients at diagnosis (chronic phase = 7; accelerared phase = 1). Mononuclear cells were incubated with syntheti c antisense 18-mer oligonucleotides complementary to the two different junctions b2a2 or b3a2. The type of junction (b2a2 or b3a2) was previ ously determined by RT-PCR techniques. Cells incubated for 12 to 14 ho urs with or without sense oligonucleotides served as controls. After i ncubation with oligonucleotides, the cell DNA synthesis was analysed b y flow cytometry using the BrdUrd/DNA method and, the cell plating eff iciency in methylcellulose was determined. In six of the seven patient s in chronic phase, there was a significant inhibition of CFU-GM produ ction which was only 68.4 +/- 19%; (p < .01) of that found in controls . The S phase index, which depends upon the percentage of S phase cell s as well as the fluorescence intensity, was 48 +/- 29% (p < .01) of t he control values for the seven patients in chronic phase. Interesting ly, for the only CML patient in accelerated phase, antisense oligomers had no inhibitory effect on either the production of CFU-GM or the nu mber of S phase cells. In improving the specificity of oligomers, it m ight be usefull for gene-targeted anti-leukemic therapy and/or bone ma rrow purging.