Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD20892, USA.
Free Radic Biol Med. 2013 Apr;57:162-75. doi: 10.1016/j.freeradbiomed.2013.01.002. Epub 2013 Jan 11.
Iodonium-class flavoprotein dehydrogenase inhibitors have been demonstrated to possess antiproliferative potential and to inhibit reactive oxygen production in human tumor cells, although the mechanism(s) that explains the relationship between altered cell growth and the generation of reactive oxygen species (ROS) remains an area of active investigation. Because of the ability of these compounds to inhibit the activity of flavoprotein-containing epithelial NADPH oxidases, we chose to examine the effects of several iodonium-class flavoprotein inhibitors on human colon cancer cell lines that express high, functional levels of a single such oxidase (NADPH oxidase 1, or Nox1). We found that diphenyleneiodonium (DPI), di-2-thienyliodonium (DTI), and iodonium diphenyl inhibited the growth of Caco2, HT-29, and LS-174T colon cancer cells at concentrations (10-250nM for DPI, 0.5-2.5μM for DTI, and 155nM to 10μM for iodonium diphenyl) substantially lower than needed for DU145 human prostate cancer cells, which do not possess functional NADPH oxidase activity. Drug treatment was associated with decreased H2O2 production and diminished intracellular ROS levels, lasting up to 24h, after short-term (1-h) exposure to the iodonium analogs. Decreased tumor cell proliferation was caused, in part, by a profound block in cell cycle progression at the G1/S interface in both LS-174T and HT-29 cells exposed to either DPI or DTI; and the G1 block was produced, for LS-174T cells, by upregulation of p27 and a drug concentration-related decrease in the expression of cyclins D1, A, and E that was partially prevented by exogenous H2O2. Not only did DPI and DTI decrease intracellular ROS, they both also significantly decreased the mRNA expression levels of Nox1, potentially contributing to the prolonged reduction in tumor cell reactive oxygen levels. We also found that DPI and DTI significantly decreased the growth of both HT-29 and LS-174T human tumor xenografts, at dose levels that produced peak plasma concentrations similar to those utilized for our in vitro experiments. These findings suggest that iodonium analogs have therapeutic potential for NADPH oxidase-containing human colon cancers in vivo and that at least part of their antineoplastic mechanism of action may be related to targeting Nox1.
碘鎓类黄素蛋白脱氢酶抑制剂已被证明具有抗增殖潜力，并能抑制人肿瘤细胞中活性氧的产生，尽管解释细胞生长变化与活性氧（ROS）产生之间关系的机制仍是一个活跃的研究领域。由于这些化合物能够抑制含黄素蛋白的上皮 NADPH 氧化酶的活性，我们选择研究几种碘鎓类黄素蛋白抑制剂对表达高水平单一此类氧化酶（NADPH 氧化酶 1 或 Nox1）的人结肠癌细胞系的影响。我们发现二苯并碘鎓（DPI）、二噻吩基碘鎓（DTI）和二苯基碘鎓抑制 Caco2、HT-29 和 LS-174T 结肠癌细胞的生长，其浓度（DPI 为 10-250nM，DTI 为 0.5-2.5μM，二苯基碘鎓为 155nM 至 10μM）远低于不具有功能性 NADPH 氧化酶活性的 DU145 人前列腺癌细胞所需的浓度。药物处理与短期（1 小时）暴露于碘鎓类似物后长达 24 小时的 H2O2 产生减少和细胞内 ROS 水平降低有关。在暴露于 DPI 或 DTI 的 LS-174T 和 HT-29 细胞中，部分通过在 G1/S 界面处细胞周期进程的严重阻断导致肿瘤细胞增殖减少；并且 LS-174T 细胞中的 G1 阻断是由 p27 的上调和细胞周期蛋白 D1、A 和 E 的表达与药物浓度相关的降低引起的，而外源性 H2O2 部分阻止了这种降低。DPI 和 DTI 不仅降低了细胞内的 ROS，还显著降低了 Nox1 的 mRNA 表达水平，这可能有助于肿瘤细胞内活性氧水平的长期降低。我们还发现 DPI 和 DTI 显著降低了 HT-29 和 LS-174T 人肿瘤异种移植物的生长，其剂量水平产生的峰值血浆浓度与我们的体外实验中使用的浓度相似。这些发现表明，碘鎓类似物在体内对含有 NADPH 氧化酶的人结肠癌具有治疗潜力，其抗肿瘤作用机制的至少一部分可能与靶向 Nox1 有关。
