Adaphostin-induced oxidative stress overcomes BCR/ABL mutation-dependent and -independent imatinib resistance.
The BCR/ABL kinase has been targeted for the treatment of chronic myelogenous leukemia (CML) by imatinib mesylate. While imatinib has been extremely effective for chronic phase CML, blast crisis CML and Ph+ acute lymphoblastic leukemia (ALL) are often resistant. In particular, mutation of the T315 residue in the bcr/abl activation loop renders cells highly resistant to imatinib and to second-generation kinase inhibitors such as BMS-354825 or AMN107. Adaphostin is a tyrphostin that was originally intended to inhibit the BCR/ABL kinase by competing with its peptide substrates. Recent findings have in addition implicated reactive oxygen species (ROS) in the cytotoxic mechanism of adaphostin. In view of this unique mode of action, we examined the effects of adaphostin on numerous imatinib-resistant leukemia models, including imatinib-resistant CML and Ph+ ALL cell lines, cells harboring point mutations in BCR/ABL, and specimens from imatinib-resistant CML patients, using assays for intracellular ROS, apoptosis, and clonogenicity. Every model of imatinib resistance examined remained fully sensitive to adaphostin-induced cell death. Collectively, these data suggest that ROS generation by adaphostin overcomes even the most potent imatinib resistance in CML and Ph+ ALL.
Chandra
Joya
J
Department of Pediatrics Research, University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA. jchandra@mdanderson.org
Tracy
Jeannette
J
Loegering
David
D
Flatten
Karen
K
Verstovsek
Srdan
S
Beran
Miloslav
M
Gorre
Mercedes
M
Estrov
Zeev
Z
Donato
Nicholas
N
Talpaz
Moshe
M
Sawyers
Charles
C
Bhalla
Kapil
K
Karp
Judith
J
Sausville
Edward
E
Kaufmann
Scott H
SH
D000218:Adamantane / Q000031:analogs & derivatives* / Q000494:pharmacology; D017209:Apoptosis; D001549:Benzamides; D045744:Cell Line, Tumor; D002999:Clone Cells; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D016044:Fusion Proteins, bcr-abl; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology*; D000068877:Imatinib Mesylate; D007938:Leukemia / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects*; D010879:Piperazines / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D011743:Pyrimidines / Q000494:pharmacology*; D017382:Reactive Oxygen Species
D001549:Benzamides; D006873:Hydroquinones; C404397:NSC 680410; D010879:Piperazines; D011743:Pyrimidines; D017382:Reactive Oxygen Species; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; D000218:Adamantane