Mutation in the ATP-binding pocket of the ABL kinase domain in an STI571-resistant BCR/ABL-positive cell line.
The major mechanism of action of STI571 is a competitive interference with the ATP-binding site of the Bcr/Abl tyrosine kinase. In the BCR/ABL-positive cell line KBM5, we studied cellular events associated with the in vitro acquisition of resistance to STI571. The emergence of the STI571-resistant phenotype was accompanied by only a marginal increase in the number of copies of the BCR/ABL gene and its level of expression. The activity of the Bcr/Abl kinase (level of autophosphorylation) in resistant cells was, however, incompletely inhibited by STI571, and the acquisition of the high degree of resistance was associated with a single-point mutation leading to a substitution of a threonine-to-isoleucine at position 315 of Abl. In the resistant KBM5-STI571(R1.0) cells, 20% of the BCR/ABL transcripts and 10% of BCR/ABL gene copies on the DNA level were mutated. The mutation was present in all 10 STI571-resistant clones derived from low density clonogenic assay, confirming its presence in all colony-forming cells but only in a fraction of the BCR/ABL gene copies in each cell. The contribution of this mutation to STI571-resistant phenotype remains unknown. Preliminary data showing partial reversibility of resistance in these cells suggest that resistance may be multifactorial. No other mutations were identified in the kinase domain of the BCR/ABL gene.
Ricci
Clara
C
Department of Leukemia, Division of Medicine, The University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Scappini
Barbara
B
Divoky
Vladimir
V
Gatto
Simona
S
Onida
Francesco
F
Verstovsek
Srdan
S
Kantarjian
Hagop M
HM
Beran
Miloslav
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001549:Benzamides; D001665:Binding Sites; D004252:DNA Mutational Analysis; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D016313:Genes, abl / Q000235:genetics*; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics*; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D000255:Adenosine Triphosphate; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl