Metabolism and toxicity of arsenic in human urothelial cells expressing rat arsenic (+3 oxidation state)-methyltransferase
Metabolism and toxicity of arsenic in human urothelial cells expressing rat arsenic (+3 oxidation state)-methyltransferase
复制标题
DOI：
10.1016/j.taap.2004.12.007
复制
发表时间：
2005-09-01
影响因子：
3.8
通讯作者：
Styblo, M
中科院分区：
文献类型：
--
作者：
Drobná, Z;Waters, SB;Styblo, M
无机 As (iAs) 的酶促甲基化由 As(+3 氧化态)-甲基转移酶 (AS3MT) 催化。 AS3MT 在大鼠肝脏和人肝细胞中表达。然而，AS3MT 在 UROtsa（不甲基化 iAs 的人类尿路上皮细胞）中不表达。因此，UROtsa 细胞是理想的零背景，可以在其中检查 iAs 甲基化在调节这种类金属的毒性和促癌作用中的作用。本研究使用逆转录病毒基因传递系统创建表达大鼠 AS3MT 的克隆 UROtsa 细胞系 (UROtsa/F35)。在这里，我们表征了表达 AS3MT 的亲本细胞和克隆细胞中亚砷酸盐 (iAs(III)) 和甲基化三价砷的代谢和细胞毒性。与亲本细胞相比，UROtsa/F35 细胞有效地甲基化 iAs(III)，产生含有 As-III 或 As-V 的甲基砷 (MAs) 和二甲基砷 (DMAs)。当暴露于 MAsIII 时，UROtsa/F35 细胞产生 DMAsIII 和 DMAsV。在 UROtsa 和 UROtsa/F35 细胞中，MAsIII 和 DMAsIII 的细胞毒性比 iAs(III) 更强。 MAsIII 或 DMAsIII 比 iAs(III) 的细胞毒性更大，这与每种甲基化三价砷的细胞摄取和保留更大有关。值得注意的是，UROtsa/F35 细胞比亲本细胞对 iAs(III) 的细胞毒性作用更敏感，但对 MAsIII 的细胞毒性更具抵抗力。 UROtsa/F35 细胞对 iAs(III) 的敏感性增加与 DMA 产生和细胞内 MA 积累的抑制有关。 UROtsa/F35 细胞对中等浓度 MAsIII 的耐药性与其快速转化为 DMA 和 DMA 流出有关。然而，抑制 UROtsa/F35 细胞产生 DMA 的 MAsn(III) 浓度对于亲本和克隆细胞系具有同样的毒性。因此，MAsIII 的产生和积累是甲基化细胞中急性 iAs 暴露毒性的关键因素。 (c) 2004 Elsevier Inc. 保留所有权利。
The enzymatic methylation of inorganic As (iAs) is catalyzed by As(+3 oxidation state)-methyltransferase (AS3MT). AS3MT is expressed in rat liver and in human hepatocytes. However, AS3MT is not expressed in UROtsa, human urothelial cells that do not methylate iAs. Thus, UROtsa cells are an ideal null background in which the role of iAs methylation in modulation of toxic and cancer-promoting effects of this metalloid can be examined. A retroviral gene delivery system was used in this study to create a clonal UROtsa cell line (UROtsa/F35) that expresses rat AS3MT. Here, we characterize the metabolism and cytotoxicity of arsenite (iAs(III)) and methylated trivalent arsenicals in parental cells and clonal cells expressing AS3MT. In contrast to parental cells, UROtsa/F35 cells effectively methylated iAs(III), yielding methylarsenic (MAs) and dimethylarsenic (DMAs) containing either As-III or As-V. When exposed to MAsIII, UROtsa/F35 cells produced DMAsIII and DMAsV. MAsIII and DMAsIII were more cytotoxic than iAs(III) in UROtsa and UROtsa/F35 cells. The greater cytotoxicity of MAsIII or DMAsIII than of iAs(III) was associated with greater cellular uptake and retention of each methylated trivalent arsenical. Notably, UROtsa/F35 cells were more sensitive than parental cells to the cytotoxic effects of iAs(III) but were more resistant to cytotoxicity of MAsIII. The increased sensitivity of UROtsa/F35 cells to iAs(III) was associated with inhibition of DMAs production and intracellular accumulation of MAs. The resistance of UROtsa/F35 cells to moderate concentrations of MAsIII was linked to its rapid conversion to DMAs and efflux of DMAs. However, concentrations of MAsn(III) that inhibited DMAs production by UROtsa/F35 cells were equally toxic for parental and clonal cell lines. Thus, the production and accumulation of MAsIII is a key factor contributing to the toxicity of acute iAs exposures in methylating cells. (c) 2004 Elsevier Inc. All rights reserved.