Park Seyeon, Han Seong-Su, Park Chan H, Hahm Eun-Ryeong, Lee Sook J, Park Hye K, Lee Se-Hoon, Kim Won S, Jung Chul Won, Park Keunchil, Riordan Hugh D, Kimler Bruce F, Kim Kihyun, Lee Je-Ho
Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
Int J Biochem Cell Biol. 2004 Nov;36(11):2180-95. doi: 10.1016/j.biocel.2004.04.005.
L-Ascorbic acid (LAA) is being investigated clinically for the treatment of patients with acute myeloid leukemia (AML) based on the observed effects of LAA on AML progenitor cells in vitro. However, the mechanism for LAA-induced cytoreduction remains to be elucidated. LAA at concentrations of 0.25-1.0 mM induced a dose- and time-dependent inhibition of proliferation in three AML cell lines and also in leukemic cells from peripheral blood specimens obtained from three patients with AML. In contrast, ovarian cancer cell lines were only minimally affected. Flow cytometric analysis showed that LAA at concentrations of 0.25-1.0 mM could significantly induce apoptosis in the AML cell lines. LAA induced oxidation of glutathione to oxidized form (GSSG) and subsequent H(2)O(2) accumulation in a concentration-dependent manner, in parallel to induction of apoptosis. The direct role of H(2)O(2) in the induction of apoptosis in AML cells was clearly demonstrated by the finding that catalase could completely abrogate LAA-induced apoptosis. Induction of apoptosis in LAA-treated AML cells involved a dose-dependent increase of Bax protein, release of cytochrome C from mitochondria to cytosol, activation of caspase 9 and caspase 3, and cleavage of poly[ADP-ribose]polymerase. In conclusion, LAA can induce apoptosis in AML cells, and this is clearly due to H(2)O(2) which accumulates intracellularly as a result of oxidation of reduced glutathione by LAA.
基于体外观察到的L-抗坏血酸（LAA）对急性髓性白血病（AML）祖细胞的作用，目前正在对其进行临床研究，以治疗AML患者。然而，LAA诱导细胞数量减少的机制仍有待阐明。浓度为0.25-1.0 mM的LAA对三种AML细胞系以及从三名AML患者外周血标本中获取的白血病细胞的增殖具有剂量和时间依赖性抑制作用。相比之下，卵巢癌细胞系仅受到轻微影响。流式细胞术分析表明，浓度为0.25-1.0 mM的LAA可显著诱导AML细胞系凋亡。LAA以浓度依赖性方式诱导谷胱甘肽氧化为氧化型（GSSG），随后H₂O₂积累，这与凋亡诱导平行。过氧化氢酶可完全消除LAA诱导的凋亡，这一发现清楚地证明了H₂O₂在AML细胞凋亡诱导中的直接作用。LAA处理的AML细胞凋亡诱导涉及Bax蛋白的剂量依赖性增加、细胞色素C从线粒体释放到细胞质、caspase 9和caspase 3的激活以及聚[ADP-核糖]聚合酶的裂解。总之，LAA可诱导AML细胞凋亡，这显然是由于LAA将还原型谷胱甘肽氧化导致细胞内积累的H₂O₂所致。
