Sumizawa Tomoyuki, Igisu Hideki
Department of Environmental Toxicology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Iseigaoka, Yahatanishi, Kitakyushu, Japan.
Arch Toxicol. 2009 Sep;83(9):817-24. doi: 10.1007/s00204-009-0438-7. Epub 2009 May 28.
In our previous study, we found that caspase-dependent apoptosis played a role in the genesis of toxicity of acrylamide in human neuroblastoma (SH-SY5Y) cells (Sumizawa and Igisu in Arch Toxicol 81:279-282, 2007). In the present experiment, we examined whether carboxyfullerene may suppress the cytotoxicity of acrylamide because carboxyfullerene has been reported to protect nerve cells from various pathologic processes including apoptosis. Carboxyfullerene lowered lactate dehydrogense leakage and elevated cell viability in SH-SY5Y cells exposed to acrylamide. It also lowered caspase-3 activities and cell population in the sub-G(1) phase induced by acrylamide. Nevertheless, carboxyfullerene enhanced cellular uptake of [(14)C]acrylamide. On the other hand, acrylamide markedly decreased glutathione (GSH)-content in cells and carboxyfullerene blocked the decrease. The toxicity of acrylamide was suppressed by adding GSH or GSH monoethyl ester, whereas it was not lowered by carboxyfullerene when GSH synthesis was inhibited by L: -buthionine-(S,R)-sulfoximine. Thus, the cytotoxicity of acrylamide including apoptotic processes is closely related to GSH level in SH-SY5Y cells and carboxyfullerene suppresses the toxicity by maintaining GSH content. Neither tricarboxylic acids without fullerene moiety nor hydroxylated fullerene showed comparable effects of carboxyfullerene (60 microM) against 1-5 mM acrylamide, suggesting the importance of the three malonic acid groups at specific positions in a fullerene molecule for the effects.
在我们之前的研究中，我们发现半胱天冬酶依赖性凋亡在丙烯酰胺对人神经母细胞瘤（SH-SY5Y）细胞的毒性发生过程中起作用（Sumizawa和Igisu，《毒理学文献》81:279 - 282，2007年）。在本实验中，我们研究了羧基富勒烯是否可以抑制丙烯酰胺的细胞毒性，因为据报道羧基富勒烯可保护神经细胞免受包括凋亡在内的各种病理过程的影响。羧基富勒烯降低了暴露于丙烯酰胺的SH-SY5Y细胞中的乳酸脱氢酶泄漏，并提高了细胞活力。它还降低了丙烯酰胺诱导的半胱天冬酶-3活性以及亚G(1)期的细胞数量。然而，羧基富勒烯增强了[(14)C]丙烯酰胺的细胞摄取。另一方面，丙烯酰胺显著降低了细胞内的谷胱甘肽（GSH）含量，而羧基富勒烯阻止了这种降低。添加GSH或GSH单乙酯可抑制丙烯酰胺的毒性，而当L-丁硫氨酸-(S,R)-亚砜亚胺抑制GSH合成时，羧基富勒烯并不能降低其毒性。因此，丙烯酰胺的细胞毒性包括凋亡过程与SH-SY5Y细胞中的GSH水平密切相关，羧基富勒烯通过维持GSH含量来抑制毒性。既没有不含富勒烯部分的三羧酸，也没有羟基化富勒烯对1 - 5 mM丙烯酰胺显示出与羧基富勒烯（60 microM）相当的作用，这表明富勒烯分子中特定位置的三个丙二酸基团对于这些作用的重要性。
