BCR-ABL point mutants isolated from patients with imatinib mesylate-resistant chronic myeloid leukemia remain sensitive to inhibitors of the BCR-ABL chaperone heat shock protein 90.
Clinical resistance to imatinib mesylate is commonly observed in patients with advanced Philadelphia chromosome- positive (Ph(+)) leukemias. Acquired resistance is typically associated with reactivation of BCR-ABL due to kinase domain mutations or gene amplification, indicating that BCR-ABL remains a viable target for inhibition in these patients. Strategies for overcoming resistance can be envisioned through exploitation of other molecular features of the BCR-ABL protein, such as its dependence on the molecular chaperone heat shock protein 90 (Hsp90). To determine whether inhibition of Hsp90 could induce degradation of imatinib mesylate-resistant, mutant BCR-ABL proteins, hematopoietic cells expressing 2 mutant BCR-ABL proteins found in imatinib mesylate-resistant patients (T315I and E255K) were examined for sensitivity to geldanamycin and 17-allylaminogeldanamycin (17-AAG). Both compounds induced the degradation of wild-type and mutant BCR-ABL and inhibited cell growth, with a trend indicating more potent activity against mutant BCR-ABL proteins. These data support clinical investigations of 17-AAG in imatinib mesylate-resistant Ph(+) leukemias.
D000970:Antineoplastic Agents / Q000633:toxicity*; D001549:Benzamides; D019008:Drug Resistance, Neoplasm; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D018841:HSP90 Heat-Shock Proteins / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D010879:Piperazines / Q000633:toxicity*; D017354:Point Mutation; D011743:Pyrimidines / Q000633:toxicity*
D000970:Antineoplastic Agents; D001549:Benzamides; D018841:HSP90 Heat-Shock Proteins; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl