Rosato Roberto R, Almenara Jorge A, Grant Steven
Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
Cancer Res. 2003 Jul 1;63(13):3637-45.
Effects of the histone deacetylase (HDAC) inhibitor MS-275 have been examined in human leukemia and lymphoma cells (U937, HL-60, K562, and Jurkat) as well as in primary acute myelogenous leukemia blasts in relation to differentiation and apoptosis. MS-275 displayed dose-dependent effects in each of the cell lines. When administered at a low concentration (e.g., 1 micro M), MS-275 exhibited potent antiproliferative activity, inducing p21(CIP1/WAF1)-mediated growth arrest and expression of differentiation markers (CD11b) in U937 cells. These events were accompanied by an increase in hypophosphorylated retinoblastoma protein and down-regulation of cell cycle-related proteins including cyclin D1. However, at higher concentrations (e.g., 5 micro M), MS-275 potently induced cell death, triggering apoptosis in approximately 70% of cells at 48 h. In contrast to other HDAC inhibitors such as apicidin, the extrinsic, receptor-mediated pathway played a minimal role in MS-275 lethality. However, MS-275 potently induced a very early (e.g., within 2 h) increase in reactive oxygen species (ROS), followed by the loss of mitochondrial membrane potential (Delta psi(m)) and cytosolic release of cytochrome c. These events culminated in activation of the caspase cascade, manifested by poly(ADP-ribose) polymerase, p21(CIP1/WAF1), p27(KIP), Bcl-2, and retinoblastoma protein degradation. MS-275 exposure also resulted in diminished expression of cyclin D1 and the antiapoptotic proteins Mcl-1 and XIAP. Administration of the free radical scavenger L-N-acetylcysteine blocked MS-275-mediated mitochondrial injury and apoptosis, suggesting a primary role for ROS generation in MS-275-associated lethality. Lastly, U937 cells stably expressing a p21(CIP1/WAF1) antisense construct were significantly more sensitive to MS-275-mediated apoptosis than controls, but they were impaired in their differentiation response. Together, these findings demonstrate that MS-275 exerts dose-dependent effects in human leukemia cells, i.e., p21(CIP1/WAF1)-dependent growth arrest and differentiation at low drug concentrations and a marked induction of ROS, mitochondrial damage, caspase activation, and apoptosis at higher concentrations.
已在人白血病和淋巴瘤细胞（U937、HL - 60、K562和Jurkat）以及原发性急性髓性白血病原始细胞中研究了组蛋白脱乙酰酶（HDAC）抑制剂MS - 275与分化和凋亡相关的作用。MS - 275在每种细胞系中均表现出剂量依赖性效应。当以低浓度（例如1微摩尔）给药时，MS - 275表现出强大的抗增殖活性，诱导U937细胞中p21（CIP1/WAF1）介导的生长停滞和分化标志物（CD11b）的表达。这些事件伴随着低磷酸化视网膜母细胞瘤蛋白的增加以及包括细胞周期蛋白D1在内的细胞周期相关蛋白的下调。然而，在较高浓度（例如5微摩尔）时，MS - 275强烈诱导细胞死亡，在48小时时约70%的细胞发生凋亡。与其他HDAC抑制剂如阿皮西丁不同，外在的、受体介导的途径在MS - 275致死性中起的作用最小。然而，MS - 275强烈诱导活性氧（ROS）非常早期（例如在2小时内）增加，随后线粒体膜电位（Δψm）丧失和细胞色素c的胞质释放。这些事件最终导致半胱天冬酶级联反应激活，表现为聚（ADP - 核糖）聚合酶、p21（CIP1/WAF1）、p27（KIP）、Bcl - 2和视网膜母细胞瘤蛋白降解。MS - 275处理还导致细胞周期蛋白D1以及抗凋亡蛋白Mcl - 1和XIAP的表达减少。给予自由基清除剂L - N - 乙酰半胱氨酸可阻断MS - 275介导的线粒体损伤和凋亡，表明ROS生成在MS - 275相关致死性中起主要作用。最后，稳定表达p21（CIP/WAF1）反义构建体 的U937细胞对MS - 275介导的凋亡比对照细胞显著更敏感，但它们的分化反应受损。总之，这些发现表明MS - 275在人白血病细胞中发挥剂量依赖性作用，即在低药物浓度下依赖p21（CIP1/WAF1）的生长停滞和分化，在较高浓度下显著诱导ROS、线粒体损伤、半胱天冬酶激活和凋亡。
