TY - JOUR
T1 - Synergistic interactions between DMAG and mitogen- activated protein kinase kinase 1/2 inhibitors in Bcr/abl+ leukemia cells sensitive and resistant to imatinib mesylate
AU - Nguyen, Tri K.
AU - Rahmani, Mohamed
AU - Gao, Ning
AU - Kramer, Lora
AU - Corbin, Amie S.
AU - Druker, Brian J.
AU - Dent, Paul
AU - Grant, Steven
PY - 2006/4/1
Y1 - 2006/4/1
N2 - Purpose: To characterize interactions between the heat shock protein 90 antagonist 17-dimethylaminoethylamino-17-demethoxygeldanamycin (DMAG) and the mitogen-activated protein kinase/extracellular signal - regulated kinase (ERK) kinase 1/2 inhibitor PD184352 in Bcr/abl+ leukemia cells sensitive and resistant to imatinib mesylate. Experimental Design: K562 and LAMA 84 cells were exposed to varying concentrations of DMAG and PD184352 for 48 hours; after which, mitochondrial integrity, caspase activation, and apoptosis were monitored. Parallel studies were done in imatinib mesylate - resistant cells, including BaF3 cells transfected with plasmids encoding clinically relevant Bcr/abl mutations conferring imatinib mesylate resistance (e.g., E255K, M351T, and T315I) and primary CD34+ bone marrow cells from patients refractory to imatinib mesylate. Results: Cotreatment of Bcr/abl+ cells with minimally toxic concentrations of DMAG and PD184352 resulted in synergistic induction of mitochondrial injury (cytochrome c release and Bax conformational change), events associated with the pronounced and sustained inactivation of ERK1/2 accompanied by down-regulation of Bcl-xL. Conversely, cells ectopically expressing Bcl-xL displayed significant protection against PD184352/DMAG - mediated lethality. This regimen effectively induced apoptosis in K562 cells overexpressing Bcr/abl, in BaF3 cells expressing various clinically relevant Bcr/abl mutations, and in primary CD34+ cells from patients resistant to imatinib mesylate, but was relatively sparing of normal CD34+ bone marrow cells. Conclusions: A regimen combining the heat shock protein 90 antagonist DMAG and the mitogen-activated protein kinase/ERK kinase 1/2 inhibitor potently induces apoptosis in Bcr/abl+ cells, including those resistant to imatinib mesylate through various mechanisms including Bcr/abl kinase mutations, through a process that may involve sustained ERK1/2 inactivation and Bcl-xL down-regulation. This strategy warrants further attention in Bcr/abl+ hematopoietic malignancies, particularly those resistant to Bcr/abl kinase inhibitors.
AB - Purpose: To characterize interactions between the heat shock protein 90 antagonist 17-dimethylaminoethylamino-17-demethoxygeldanamycin (DMAG) and the mitogen-activated protein kinase/extracellular signal - regulated kinase (ERK) kinase 1/2 inhibitor PD184352 in Bcr/abl+ leukemia cells sensitive and resistant to imatinib mesylate. Experimental Design: K562 and LAMA 84 cells were exposed to varying concentrations of DMAG and PD184352 for 48 hours; after which, mitochondrial integrity, caspase activation, and apoptosis were monitored. Parallel studies were done in imatinib mesylate - resistant cells, including BaF3 cells transfected with plasmids encoding clinically relevant Bcr/abl mutations conferring imatinib mesylate resistance (e.g., E255K, M351T, and T315I) and primary CD34+ bone marrow cells from patients refractory to imatinib mesylate. Results: Cotreatment of Bcr/abl+ cells with minimally toxic concentrations of DMAG and PD184352 resulted in synergistic induction of mitochondrial injury (cytochrome c release and Bax conformational change), events associated with the pronounced and sustained inactivation of ERK1/2 accompanied by down-regulation of Bcl-xL. Conversely, cells ectopically expressing Bcl-xL displayed significant protection against PD184352/DMAG - mediated lethality. This regimen effectively induced apoptosis in K562 cells overexpressing Bcr/abl, in BaF3 cells expressing various clinically relevant Bcr/abl mutations, and in primary CD34+ cells from patients resistant to imatinib mesylate, but was relatively sparing of normal CD34+ bone marrow cells. Conclusions: A regimen combining the heat shock protein 90 antagonist DMAG and the mitogen-activated protein kinase/ERK kinase 1/2 inhibitor potently induces apoptosis in Bcr/abl+ cells, including those resistant to imatinib mesylate through various mechanisms including Bcr/abl kinase mutations, through a process that may involve sustained ERK1/2 inactivation and Bcl-xL down-regulation. This strategy warrants further attention in Bcr/abl+ hematopoietic malignancies, particularly those resistant to Bcr/abl kinase inhibitors.
UR - http://www.scopus.com/inward/record.url?scp=33646227904&partnerID=8YFLogxK
U2 - 10.1158/1078-0432.CCR-05-2282
DO - 10.1158/1078-0432.CCR-05-2282
M3 - Article
C2 - 16609040
AN - SCOPUS:33646227904
SN - 1078-0432
VL - 12
SP - 2239
EP - 2247
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 7 I
ER -