Kirkpatrick D L, Sa'da I A, Chernoff W, Kuperus M
Department of Chemistry, University of Regina, Saskatchewan, Canada.
Oncol Res. 1994;6(10-11):545-52.
The cytotoxicity of the disulfide n-butyl 2-imidazolyl disulfide (III-2) was determined to be the result of a disruption in the cellular redox state and inhibition of critical membrane enzymes. These events cause perturbations in Ca2+ homeostasis, which may affect the cell signalling machinery and cause the activation of catabolic enzymes. Exposure of EMT6 cells to III-2 resulted in depletion of nonprotein and protein thiols. Under hypoxic conditions, the depletion of reduced glutathione was less than that measured when cells were treated in air, whereas following an exposure to 500 microM III-2 for 2 h the enzymes glutathione S-transferase and glutathione reductase were inhibited to a greater extent under hypoxia. Ca2+ homeostasis was disrupted with an initial shift from the mitochondrial to the cytoplasmic pool. The inhibition of plasma membrane Ca(2+)-ATPase resulted in accumulation of Ca2+ in the cytoplasm. At higher concentrations, further disruption was seen as a net loss of Ca2+ of the cytoplasmic excess with no change in the mitochondrial levels, resulting in lower total cellular Ca2+. Neither the inhibition of Ca(2+)-ATPase nor the disruption of Ca2+ homeostasis were different under hypoxic vs. oxic conditions. Due to these observations, HL60 cells were used to measure whether III-2 stimulated apoptosis. Morphologic changes and DNA laddering were observed following exposure to the disulfide, with lower concentrations required to stimulate the cellular changes under hypoxia. These events may be the result of the disruption in Ca2+ homeostasis due to thiolation or alteration in redox status of the cells.(ABSTRACT TRUNCATED AT 250 WORDS)
二硫代正丁基2-咪唑基二硫化物（III-2）的细胞毒性被确定是细胞氧化还原状态破坏和关键膜酶抑制的结果。这些事件导致Ca2+稳态紊乱，这可能会影响细胞信号传导机制并导致分解代谢酶的激活。EMT6细胞暴露于III-2会导致非蛋白质和蛋白质硫醇的消耗。在缺氧条件下，还原型谷胱甘肽的消耗比在空气中处理细胞时测得的要少，而在暴露于500 microM III-2 2小时后，谷胱甘肽S-转移酶和谷胱甘肽还原酶在缺氧条件下受到的抑制程度更大。Ca2+稳态被破坏，最初从线粒体池转移到细胞质池。质膜Ca(2+)-ATPase的抑制导致Ca2+在细胞质中积累。在较高浓度下，进一步的破坏表现为细胞质中过量Ca2+的净损失，而线粒体水平没有变化，导致细胞内总Ca2+降低。在缺氧与有氧条件下，Ca(2+)-ATPase的抑制和Ca2+稳态的破坏没有差异。基于这些观察结果，使用HL60细胞来测量III-2是否刺激细胞凋亡。暴露于二硫化物后观察到形态学变化和DNA梯状条带，在缺氧条件下刺激细胞变化所需的浓度较低。这些事件可能是由于细胞硫醇化或氧化还原状态改变导致Ca2+稳态破坏的结果。（摘要截断于250字）
