Fiorucci S, Distrutti E, Ajuebor M N, Mencarelli A, Mannucci R, Palazzetti B, Del Soldato P, Morelli A, Wallace J L
Clinica di Gastroenterologia ed Epatologia, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Perugia, 06100 Perugia, Italy.
Am J Physiol Gastrointest Liver Physiol. 2001 Sep;281(3):G654-65. doi: 10.1152/ajpgi.2001.281.3.G654.
The activation of a self-amplifying cascade of caspases, of which caspase-8 is the apical protease, mediates Fas-, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-, and TNF-alpha-induced apoptosis in colon cell lines. Nitric oxide (NO) protects from apoptosis induced by Fas and TNF-alpha. We examined whether NCX-456, an NO-releasing derivative of mesalamine, protects colon epithelial cells from cytokine-induced apoptosis. Caco-2 and HT-29 cell lines express death factor receptors and are driven to apoptosis in response to incubation with Fas-agonistic antibody, TNF-alpha/interferon-gamma, and TRAIL. The two novel observations reported here are that 1) cotreatment of cells with NCX-456, but not mesalamine, resulted in concentration-dependent protection against death factor-induced apoptosis and inhibition of caspase activity, and 2) exposure to dithiothreitol, an agent that effectively removes NO from thiol groups, resulted in a 70% recovery of caspase activity, which is consistent with S-nitrosation as a major mechanism for caspase inactivation. These data suggest that caspase S-nitrosation represents a mechanism for protection of colonic mucosal epithelial cells from death factor-induced death.
半胱天冬酶的自我扩增级联反应被激活，其中半胱天冬酶-8是顶端蛋白酶，介导结肠细胞系中Fas、肿瘤坏死因子（TNF）相关凋亡诱导配体（TRAIL）和TNF-α诱导的凋亡。一氧化氮（NO）可保护细胞免受Fas和TNF-α诱导的凋亡。我们研究了美沙拉嗪的NO释放衍生物NCX-456是否能保护结肠上皮细胞免受细胞因子诱导的凋亡。Caco-2和HT-29细胞系表达死亡因子受体，并在与Fas激动性抗体、TNF-α/干扰素-γ和TRAIL孵育后被诱导凋亡。本文报道的两个新发现是：1）用NCX-456而非美沙拉嗪共同处理细胞，可产生浓度依赖性地保护细胞免受死亡因子诱导的凋亡并抑制半胱天冬酶活性；2）暴露于二硫苏糖醇（一种能有效从硫醇基团中去除NO的试剂）后，半胱天冬酶活性恢复了70%，这与S-亚硝基化作为半胱天冬酶失活的主要机制一致。这些数据表明，半胱天冬酶S-亚硝基化是保护结肠黏膜上皮细胞免受死亡因子诱导死亡的一种机制。
