Jing Y, Dai J, Chalmers-Redman R M, Tatton W G, Waxman S
Rochelle Belfer Chemotherapy Foundation Laboratory, Division of Neoplastic Diseases, Department of Medicine, Mount Sinai Medical Center, New York, NY, USA.
Blood. 1999 Sep 15;94(6):2102-11.
Low concentrations of As(2)O(3) (</=1 micromol/L) induce long-lasting remission in patients with acute promyelocytic leukemia (APL) without significant myelosuppressive side effects. Several groups, including ours, have shown that 0.5 to 1 micromol/L As(2)O(3) induces apoptosis in APL-derived NB4 cells, whereas other leukemic cells are resistant to As(2)O(3) or undergo apoptosis only in response to greater than 2 micromol/L As(2)O(3). In this report, we show that the ability of As(2)O(3) to induce apoptosis in leukemic cells is dependent on the activity of the enzymes that regulate cellular H(2)O(2) content. Thus, NB4 cells have relatively low levels of glutathione peroxidase (GPx) and catalase and have a constitutively higher H(2)O(2) content than U937 monocytic leukemia cells. Glutathione-S-transferase pi (GSTpi), which is important for cellular efflux of As(2)O(3), is also low in NB4 cells. Moreover, As(2)O(3) further inhibits GPX activity and increases cellular H(2)O(2) content in NB4 but not in U937 cells. Selenite pretreatment of NB4 cells increases the activity of GPX, lowers cellular H(2)O(2) levels, and renders NB4 cells resistant to 1 micromol/L As(2)O(3). In contrast, concentrations of As(2)O(3) that alone are not capable of inducing apoptosis in NB4 cells induce apoptosis in the presence of the GPx inhibitor mercaptosuccinic acid. Similar effects are observed by modulating the activity of catalase with its inhibitor, aminotriazol. More important from a therapeutic point of view, U937 and HL-60 cells, which require high concentrations of As(2)O(3) to undergo apoptosis, become sensitive to low, clinically acceptable concentrations of As(2)O(3) when cotreated with these GPx and catalase inhibitors. The induction of apoptosis by As(2)O(3) involves an early decrease in cellular mitochondrial membrane potential and increase in H(2)O(2) content, followed by cytochrome c release, caspase 3 activation, DNA fragmentation, and the classic morphologic changes of apoptosis.
低浓度的三氧化二砷（≤1微摩尔/升）可使急性早幼粒细胞白血病（APL）患者获得持久缓解，且无明显的骨髓抑制副作用。包括我们小组在内的多个研究团队均已表明，0.5至1微摩尔/升的三氧化二砷可诱导APL来源的NB4细胞凋亡，而其他白血病细胞对三氧化二砷具有抗性，或仅在三氧化二砷浓度大于2微摩尔/升时才会发生凋亡。在本报告中，我们表明三氧化二砷诱导白血病细胞凋亡的能力取决于调节细胞过氧化氢（H₂O₂）含量的酶的活性。因此，NB4细胞中的谷胱甘肽过氧化物酶（GPx）和过氧化氢酶水平相对较低，且其过氧化氢含量比U937单核细胞白血病细胞持续更高。对三谷对于三氧化二砷的细胞外排很重要的谷胱甘肽 - S - 转移酶π（GSTpi）在NB4细胞中也较低。此外，三氧化二砷可进一步抑制NB4细胞中的GPX活性并增加细胞内过氧化氢含量，但对U937细胞则无此作用。用亚硒酸盐预处理NB4细胞可增加GPX的活性，降低细胞内过氧化氢水平，并使NB4细胞对1微摩尔/升的三氧化二砷产生抗性。相反，单独使用时不能诱导NB4细胞凋亡的三氧化二砷浓度，在存在GPx抑制剂巯基琥珀酸的情况下可诱导细胞凋亡。用其抑制剂氨基三唑调节过氧化氢酶的活性也可观察到类似效果。从治疗角度来看更重要的是，需要高浓度三氧化二砷才能发生凋亡的U937和HL - 60细胞，在与这些GPx和过氧化氢酶抑制剂共同处理时，会对低浓度且临床上可接受的三氧化二砷变得敏感。三氧化二砷诱导细胞凋亡涉及细胞线粒体膜电位早期下降和过氧化氢含量增加，随后是细胞色素c释放、半胱天冬酶3激活、DNA片段化以及凋亡的典型形态学变化。
