Mechanisms of autoinhibition and STI-571/imatinib resistance revealed by mutagenesis of BCR-ABL.
The Bcr-Abl fusion protein kinase causes chronic myeloid leukemia and is targeted by the signal transduction inhibitor STI-571/Gleevec/imatinib (STI-571). Sequencing of the BCR-ABL gene in patients who have relapsed after STI-571 chemotherapy has revealed a limited set of kinase domain mutations that mediate drug resistance. To obtain a more comprehensive survey of the amino acid substitutions that confer STI-571 resistance, we performed an in vitro screen of randomly mutagenized BCR-ABL and recovered all of the major mutations previously identified in patients and numerous others that illuminate novel mechanisms of acquired drug resistance. Structural modeling implies that a novel class of variants acts allosterically to destabilize the autoinhibited conformation of the ABL kinase to which STI-571 preferentially binds. This screening strategy is a paradigm applicable to a growing list of target-directed anti-cancer agents and provides a means of anticipating the drug-resistant amino acid substitutions that are likely to be clinically problematic.
Azam
Mohammad
M
Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA.
Latek
Robert R
RR
Daley
George Q
GQ
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001549:Benzamides; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D014644:Genetic Variation; D006801:Humans; D000068877:Imatinib Mesylate; D020128:Inhibitory Concentration 50; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010879:Piperazines / Q000494:pharmacology*; D017354:Point Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D011743:Pyrimidines / Q000494:pharmacology*
D000970:Antineoplastic Agents; D001549:Benzamides; D004791:Enzyme Inhibitors; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases