Selective Inhibition of Leukemia Cell Proliferation by BCR-ABL Antisense Oligodeoxynucleotides

Abstract

To determine the role of the BCR-ABL gene in the proliferation of blast cells of patients with chronic myelogenous leukemia, leukemia blast cells were exposed to synthetic 18-mer oligodeoxynucleotides complementary to two identified BCR-ABL junctions. Leukemia colony formation was suppressed, whereas granulocyte-macrophage colony formation from normal marrow progenitors was unaffected. When equal proportions of normal marrow progenitors and blast cells were mixed, exposed to the oligodeoxynucleotides, and assayed for residual colony formation, the majority of residual cells were normal. These findings demonstrate the requirement for a functional BCR-ABL gene in maintaining the leukemic phenotype and the feasibility of gene-targeted selective killing of neoplastic cells.

The presence of the Rb c-box peptide in the cytoplasm inhibits p210bcr-abl transforming function

“…This inhibition of colony formation was not observed in similar experiments in which the Rb C-box peptide was co-electroporated with the zeomycin cDNA dominant selection marker into tet32D cells in the presence of IL3. These experiments are consistent with earlier reports by Calabretta and his coworkers, who observed inhibition of proliferation of p210 bcr-abl dependent cells when the bcr-abl antisense oligonucleotides were used (Szczylik et al, 1991). The results of these experiments suggest that the interaction between the p210 bcr-abl and the Rb C-box is highly speci®c.…”

BCR – ABL accelerates C2-ceramide-induced apoptosis

“…These include an increased tyrosine kinase activity and an exclusively cytoplasmic localization (Konopka and Witte, 1985;Van Etten et al, 1989). The concordance observed between the presence of the BCR ± ABL gene and the development of CML in humans (Bartram et al, 1983;Wiedemann et al, 1988), as well as laboratory studies of BCR ± ABL gene transfer to normal cells (Daley et al, 1990;Kelliher et al, 1990) and antisense e ects seen in BCR ± ABL + cells (Szczylik et al, 1991), argue that p210 BCR ± ABL plays a critical role in the pathogenesis of CML. Because the tyrosine kinase function of p210 BCR ± ABL is essential to its transforming ability (Lugo et al, 1990;Cortez et al, 1995), it has been anticipated that identi®cation of its substrates would facilitate elucidation of the mechanisms by which BCR ± ABL-transformed hematopoietic stem cells initiate CML in humans.…”

Antisense inhibition of P210bcr‐ablin chronic myeloid leukemia

“…In the last few years, different authors have described potentially fruitful approaches toward selective growth inhibition of Philadelphia-positive leukemic cells by antisense molecules [ 10,11,[13][14][15]19,16]. These experiments have been performed using various experimental conditions: cell lines in culture, fresh CML cells in culture, and animal models.…”

“…In the last two years, unmodified oligonucleotides targeted to the bcr-abl junctional sequences [14,161 or against the c-myb transcript [ 1 11 were shown to have a specific effect on the growth of CML leukemic progenitors as demonstrated by colony assays. The authors investigated the effects of the antisense oligonucleotides in a specific context-cells from CML in blast crisis [14], chronic phase [16], or both [ 1 11-and did not examine the amount of transcripts or the level of expression of P210 during or just after incubation.…”

“…The authors investigated the effects of the antisense oligonucleotides in a specific context-cells from CML in blast crisis [14], chronic phase [16], or both [ 1 11-and did not examine the amount of transcripts or the level of expression of P210 during or just after incubation. Again, a preferential non-specific toxicity of the antisense oligomers (especially for phosphorothioates at relatively high doses) or of their degradation products (for phosphodiesters mainly) cannot always be excluded, and only investigating the target RNA or protein can provide a reliable proof of the specificity of the observed effects.…”