Qu Wei, Liu Jie, Fuquay Richard, Shimoda Ryuya, Sakurai Teruaki, Saavedra Joseph E, Keefer Larry K, Waalkes Michael P
Inorganic Carcinogenesis Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at the National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
Nitric Oxide. 2005 Mar;12(2):114-20. doi: 10.1016/j.niox.2005.01.005.
The liver is an important target tissue of cadmium. The compound O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2 diolate (V-PYRRO/NO) is a liver-selective nitric oxide (NO) prodrug that is metabolized by hepatic P450 enzymes to release NO in hepatocytes. In vivo, V-PYRRO/NO can protect against the toxicity of various hepatotoxicants, including cadmium. Since NO is an effective vasodilator, whether this protective effect against cadmium toxicity is at the level of the hepatic vascular system or actually within the liver cells has not been defined. Thus, we studied the effects of V-PYRRO/NO pretreatment on cadmium-induced toxicity and apoptosis in cultured rat liver epithelial (TRL 1215) cells. Cells were pretreated with V-PYRRO/NO at 500 or 1000 microM for up to 24 h, then exposed to cadmium (as CdCl2) for additional 24 h and cytotoxicity was measured. Cadmium was significantly less cytotoxic in V-PYRRO/NO (1000 microM) pretreated cells (LC50=6.1+/-0.6 microM) compared to control cells (LC50=3.5+/-0.4 microM). TRL 1215 cells acted upon the prodrug to release NO, producing nitrite levels in the extracellular media after 24 h of exposure to 500 or 1000 microM V-PYRRO/NO measured at 87.0+/-4.2 and 324+/-14.8 microM, respectively, compared to basal levels of 7.70+/-0.46 microM. V-PYRRO/NO alone produced small increases in metallothionein (MT), a metal-binding protein associated with cadmium tolerance. However, V-PYRRO/NO pretreatment greatly enhanced cadmium induction of MT. V-PYRRO/NO pretreatment also markedly reduced apoptotic cell death induced by cadmium (5 microM), apparently by blocking cadmium-induced activation of the c-Jun N-terminal kinase (JNK) pathway. Thus, the prodrug, V-PYRRO/NO, protects against the adverse effects of cadmium directly within rat liver cells apparently through generation of NO and, at least in part, by facilitation of cadmium-induced MT synthesis.
肝脏是镉的重要靶组织。化合物O2 - 乙烯基1 -（吡咯烷 - 1 - 基）重氮 - 1,2 - 二醇盐（V - PYRRO/NO）是一种肝脏选择性一氧化氮（NO）前药，可被肝脏P450酶代谢，在肝细胞中释放NO。在体内，V - PYRRO/NO可以保护机体免受包括镉在内的各种肝毒性物质的毒性作用。由于NO是一种有效的血管舒张剂，这种对镉毒性的保护作用是在肝血管系统水平还是实际上在肝细胞内尚未明确。因此，我们研究了V - PYRRO/NO预处理对培养的大鼠肝上皮（TRL 1215）细胞中镉诱导的毒性和凋亡的影响。细胞用500或1000 microM的V - PYRRO/NO预处理长达24小时，然后再暴露于镉（以CdCl2形式）24小时，并测量细胞毒性。与对照细胞（LC50 = 3.5±0.4 microM）相比，在V - PYRRO/NO（1000 microM）预处理的细胞中，镉的细胞毒性明显降低（LC50 = 6.1±0.6 microM）。TRL 1215细胞作用于前药释放NO，在暴露于500或1000 microM V - PYRRO/NO 24小时后，细胞外培养基中的亚硝酸盐水平分别为87.0±4.2和324±14.8 microM，而基础水平为7.70±0.46 microM。单独的V - PYRRO/NO使金属硫蛋白（MT）略有增加，MT是一种与镉耐受性相关的金属结合蛋白。然而，V - PYRRO/NO预处理大大增强了镉对MT的诱导作用。V - PYRRO/NO预处理还明显减少了镉（5 microM）诱导的凋亡细胞死亡，显然是通过阻断镉诱导的c - Jun N末端激酶（JNK）途径。因此，前药V - PYRRO/NO显然通过产生NO并至少部分地通过促进镉诱导的MT合成，在大鼠肝细胞内直接保护机体免受镉的不良影响。
