The lethal effects of pharmacological cyclin-dependent kinase inhibitors in human leukemia cells proceed through a phosphatidylinositol 3-kinase/Akt-dependent process.
The lethal effects of pharmacological cyclin-dependent kinase inhibitors in human leukemia cells proceed through a phosphatidylinositol 3-kinase/Akt-dependent process.
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发表时间：
2003-04
期刊：
影响因子：
11.2
通讯作者：
Chunrong Yu;M. Rahmani;Yun Dai;D. Conrad;G. Krystal;P. Dent;S. Grant
中科院分区：
文献类型：
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作者：
Chunrong Yu;M. Rahmani;Yun Dai;D. Conrad;G. Krystal;P. Dent;S. Grant
研究了PI 3 K（磷脂酰肌醇3-激酶）通路中断对人白血病细胞对药物性细胞周期蛋白依赖性激酶（CDK）抑制剂的反应的影响。将U937单核细胞白血病细胞暴露于最低毒性浓度的flavopiridol（FP）、roscovitine或CGP 74514 A 3 h，并结合PI 3 K抑制剂LY 294002（本文中缩写为LY），导致Akt磷酸化显著降低。细胞共暴露于LY和CDK抑制剂也导致早期（即，3小时内）和线粒体损伤的显著增加[例如，细胞色素c、第二类胱天蛋白酶衍生激活剂/具有低等电点的凋亡（IAP）直接抑制剂结合蛋白（Smac/DIABLO）和凋亡起始因子（AIF）释放]、胱天蛋白酶激活和凋亡。在多种其他白血病细胞类型中观察到类似的相互作用（例如，HL-60、Jurkat、Raji和NB 4）。凋亡，诱导FP/LY，基本上被阻断异位表达Bcl-2，但在相当小的程度上由显性负性caspase-8。FP诱导的细胞凋亡不被蛋白激酶（PK）A（H89）、PKC（GFX）、丝裂原活化蛋白（MAP）/细胞外信号调节激酶（ERK）激酶抑制剂增强。（MEK 1/2; U 0126），p38 MAP激酶（MAPK; SB 202190），雷帕霉素的m-靶标（TOR;雷帕霉素），或共济失调-毛细血管扩张突变（ATM;咖啡因），而PI 3 K抑制剂渥曼青霉素产生的效果与LY相似。LY对CDK激酶诱导的细胞凋亡的显著增强伴随着Bad磷酸化的减少、Bcl-2裂解的诱导以及X连锁IAP（XIAP）和Mcl-1的下调。暴露于CDK抑制剂+ LY的细胞也表现出糖原合成酶激酶（GSK）-3、叉头转录因子（FKHR）、p70（S6 K）和ERK的磷酸化减少，但p34（cdc 2）和p38 MAPK的活化增加。LY/CDK受体处理的细胞还显示CDK 2和CDK 4特异性位点上pRb去磷酸化减少，视网膜母细胞瘤蛋白裂解和细胞周期蛋白D下调（1）。诱导表达的组成型活性（豆蔻酸）Akt显着，虽然部分，衰减与FP单独或FP和LY的组合处理的Jurkat白血病细胞的凋亡。最后，LY和FP联合治疗导致从急性髓细胞白血病患者获得的原发性白血病原始细胞凋亡显著增加。总之，这些研究结果表明，PI 3 K/Akt通路在调节人白血病细胞对药物CDK抑制剂的凋亡反应中起着重要作用，并提高了CDK和PI 3 K相关通路的联合中断可能代表血液恶性肿瘤的新治疗策略的可能性。
The impact of disruption of the PI3K (phosphatidylinositol 3-kinase) pathway on the response of human leukemia cells to pharmacological cyclin-dependent kinase (CDK) inhibitors has been examined. Exposure of U937 monocytic leukemia cells to minimally toxic concentrations of flavopiridol (FP), roscovitine, or CGP74514A for 3 h in conjunction with the PI3K inhibitor LY294002 (abbreviated LY in the article) resulted in a marked decrease in Akt phosphorylation. Coexposure of cells to LY and CDK inhibitors also resulted in an early (i.e., within 3 h) and striking increase in mitochondrial damage [e.g., cytochrome c, second mitochondria-derived activator of caspases/direct inhibitor of apoptosis (IAP)-binding protein with low isoelectric point (Smac/DIABLO), and apoptosis-initiating factor (AIF) release], caspase activation, and apoptosis. Similar interactions were observed in a variety of other leukemia cell types (e.g., HL-60, Jurkat, Raji, and NB4). Apoptosis, induced by FP/LY, was substantially blocked by ectopic expression of Bcl-2, but to a considerably lesser extent by dominant-negative caspase-8. FP-induced apoptosis was not enhanced by agents that inhibited protein kinase (PK) A (H89), PKC (GFX), mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK1/2; U0126), p38 MAP kinase (MAPK; SB202190), m-target of rapamycin (TOR; rapamycin), or ataxia-telangiectasia mutation (ATM; caffeine), whereas the PI3K inhibitor wortmannin exerted effects similar to those of LY. The dramatic potentiation of CDK inhibitor-induced apoptosis by LY was accompanied by diminished Bad phosphorylation, induction of Bcl-2 cleavage, and down-regulation of X-linked IAP (XIAP) and Mcl-1. Cells exposed to CDK inhibitors + LY also exhibited reduced phosphorylation of glycogen synthase kinase (GSK)-3, forkhead transcription factor (FKHR), p70(S6K), and ERK, but increased activation of p34(cdc2) and p38 MAPK. LY/CDK inhibitor-treated cells also displayed diminished pRb dephosphorylation on CDK2- and CDK4-specific sites, retinoblastoma protein cleavage, and down-regulation of cyclin D(1). Inducible expression of constitutively active (myristolated) Akt significantly, albeit partially, attenuated apoptosis in Jurkat leukemia cells treated with either FP alone or the combination of FP and LY. Finally, cotreatment with LY and FP resulted in a dramatic increase in apoptosis in primary leukemic blasts obtained from a patient with acute myeloblastic leukemia. Together, these findings suggest that the PI3K/Akt pathway plays a major role in regulating the apoptotic response of human leukemia cells to pharmacological CDK inhibitors and raise the possibility that combined interruption of CDK- and PI3K-related pathways may represent a novel therapeutic strategy in hematological malignancies.