17-(dimethylaminoethylamino)-17-demethoxygeldanamycin and Leukemia

To investigate the role of HSP90 in proliferation and apoptosis of leukemia cells K562 through detecting the effect of HSP90 inhibitors 17-[2-(Dimethylamino) ethyl] amino-17-desmethoxygeldanamycin(17-DMAG) on leukemia K562 cell lines.. The K562 cells were treated with HSP90 inhibitors 17-DMAG, the semi-quantitative PCR was used to detect HSP90 gene expression, the WST was used to detect the effect 17-DMAG on cell proliferation as well as Annexin V flow cytometry was used to detect the cell apoptosis.. After 17-DMAG treated the K562 cells in different stage, the K562 cell growth was obviously inhibited with time dependent (48 h)(r=0.9918) and dose dependent(3.2 µmol/L) manners (r=0.9999) (P<0.01); after the K562 cells in different stage were treated with different concentrations of 17-DMAG, the K562 cells showed significant apoptosis and with dosage-dependent mauner (r=0.9903)(P<0.01); HSP90 mRNA expression decreased significantly after K562 cells were treated with different concentrations of 17-DMAG for 48 hours. 17-DAMG down-regulated the HSP90 mRNA expression in dosage-dependent mauner as well(r=0.9227) (P<0.01).. HSP90 inhibitor 17-DMAG can inhibit the proliferation of K562 cells and induce their apoptosis. This study result provides laboratory basis for the treatment of leukemia patients with 17-DMAG.

Topics: Apoptosis; Benzoquinones; Cell Proliferation; HSP90 Heat-Shock Proteins; Humans; K562 Cells; Lactams, Macrocyclic; Leukemia

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.. 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.. 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-x(L). Conversely, cells ectopically expressing Bcl-x(L) 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.. 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-x(L) down-regulation. This strategy warrants further attention in Bcr/abl(+) hematopoietic malignancies, particularly those resistant to Bcr/abl kinase inhibitors.

Topics: Antineoplastic Agents; Apoptosis; Benzamides; Benzoquinones; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Drug Synergism; Enzyme Inhibitors; Fusion Proteins, bcr-abl; Humans; Imatinib Mesylate; Lactams, Macrocyclic; Leukemia; Piperazines; Pyrimidines; Quinones; Rifabutin; Sensitivity and Specificity; Structure-Activity Relationship; Time Factors; Tumor Cells, Cultured