Nguyen Tri K, Rahmani Mohamed, Gao Ning, Kramer Lora, Corbin Amie S, Druker Brian J, Dent Paul, Grant Steven
Department of Medicine, Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia, USA.
Clin Cancer Res. 2006 Apr 1;12(7 Pt 1):2239-47. doi: 10.1158/1078-0432.CCR-05-2282.
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.
在对甲磺酸伊马替尼敏感和耐药的Bcr/abl(+)白血病细胞中，表征热休克蛋白90拮抗剂17-二甲基氨基乙基氨基-17-去甲氧基格尔德霉素（DMAG）与丝裂原活化蛋白激酶/细胞外信号调节激酶（ERK）激酶1/2抑制剂PD184352之间的相互作用。
将K562和LAMA 84细胞暴露于不同浓度的DMAG和PD184352中48小时；之后，监测线粒体完整性、半胱天冬酶激活和细胞凋亡情况。在甲磺酸伊马替尼耐药细胞中进行了平行研究，包括用编码赋予甲磺酸伊马替尼耐药性的临床相关Bcr/abl突变（如E255K、M351T和T315I）的质粒转染的BaF3细胞，以及来自对甲磺酸伊马替尼难治的患者的原代CD34(+)骨髓细胞。
用最低毒性浓度的DMAG和PD184352联合处理Bcr/abl(+)细胞，导致线粒体损伤（细胞色素c释放和Bax构象变化）的协同诱导，这些事件与ERK1/2的显著且持续失活以及Bcl-x(L)的下调相关。相反，异位表达Bcl-x(L)的细胞对PD184352/DMAG介导的致死性表现出显著的保护作用。该方案有效诱导了过表达Bcr/abl的K562细胞、表达各种临床相关Bcr/abl突变的BaF3细胞以及对甲磺酸伊马替尼耐药患者的原代CD34(+)细胞中的细胞凋亡，但对正常CD34(+)骨髓细胞的影响相对较小。
热休克蛋白90拮抗剂DMAG与丝裂原活化蛋白激酶/ERK激酶1/2抑制剂联合使用的方案可有效诱导Bcr/abl(+)细胞凋亡，包括那些通过包括Bcr/abl激酶突变在内的各种机制对甲磺酸伊马替尼耐药的细胞，这一过程可能涉及ERK1/2的持续失活和Bcl-x(L)的下调。该策略在Bcr/abl(+)造血恶性肿瘤中，尤其是那些对Bcr/abl激酶抑制剂耐药的肿瘤中，值得进一步关注。
