Antioxidant Enzymes and Cell Cycle Checkpoint Pathways

作为氧化反应的副产物产生的活性氧物质（ROS：超氧化物和过氧化氢） 能量代谢已被证明是生理信号传导过程的重要介质。这 建议被设计为测试ROS（即，超氧化物和过氧化氢）调节 通过氧化还原调节G1细胞周期调节蛋白从G1期进展到S期。这 假设是基于我们的观察，在G！正常相位 成纤维细胞周期似乎是刺激进入S期所必需的（Cancer Research 63：2109-2117，2003）。此外，我们还发现抗氧化酶（磷脂酶）的过度表达， 过氧化氢谷胱甘肽过氧化物酶和锰超氧化物歧化酶诱导人乳腺癌生长延迟 和前列腺癌细胞（Free Radical Research 37：621-630，2003; Oncogene，24：77-89，2005）。这些 观察表明，细胞周期的氧化还原调节可以提供细胞之间的机械联系， 周期调节蛋白和氧化代谢过程所必需的成功完成 每个细胞周期阶段。提出了三个具体目标来严格检验所述假设： 目的1：确定代谢超氧化物和过氧化氢的细胞内抗氧化酶 （MnSOD、CuZnSOD、过氧化氢酶和/或谷胱甘肽过氧化物酶）调节细胞周期进程 在非恶性小鼠和人类成纤维细胞中从GI到S。 目的2：确定超氧化物和过氧化氢的稳态水平是否随细胞进展而波动 通过细胞周期的各个阶段，如果ROS在不同阶段之间的波动， 细胞周期由抗氧化酶表达的变化介导。 目的3：确定抗氧化酶介导的从GI到S进展的改变是否由以下因素引起： 细胞周期蛋白D1表达的氧化还原调节的变化。 细胞内氧化还原环境和细胞周期进程的机制评估可能会导致更好的 了解正常和异常的细胞增殖。由于增殖性疾病是一种 各种人类病理生理状况，包括正常组织损伤以及肿瘤细胞反应 在癌症治疗过程中，完成本提案中的研究所获得的结果可以提供 生物化学原理操纵细胞增殖以改善结果。

Reactive oxygen species (ROS: superoxide and hydrogen peroxide) produced as by products of oxidative energy metabolism have been shown to be important mediators of physiologic signaling processes. This proposal is designed to test the hypothesis that ROS(i.e., superoxide and hydrogen peroxide) regulate progression from G1 to S phase via redox regulation of G1 cell cycle regulatory proteins. This hypothesis is based on our observations that a pro-oxidant signal at the end of the G! phase of the normal fibroblast cell cycle appears to be necessary for stimulation of entry into S-phase (Cancer Research 63:2109-2117, 2003). Furthermore, we have shown over expression of antioxidant enzymes (phospholipid hydroperoxide glutathione peroxidase and Mn-superoxide dismutase) induce a Grdelay in human breast and prostate cancer cells (Free Radical Research 37:621-630, 2003; Oncogene, 24:77-89, 2005). These observations suggest that redox regulation of the cell cycle could provide a mechanistic link between the cell cycle regulatory proteins and the oxidative metabolic processes necessary for the successful completion of each cell cycle phase. Three specific aims are proposed to rigorously test the stated hypothesis: Aim 1: Determine if intracellular antioxidant enzymes that metabolize superoxide and hydrogen peroxide (MnSOD, CuZnSOD, catalase and/or glutathione peroxidase) modulate cell cycle progression from GI to S in nonmalignant mouse and human fibroblasts. Aim 2: Determine if steady-state levels of superoxide and hydrogen peroxide fluctuate as cells progress through the various phases of the cell cycle and if fluctuations in ROS between different phases of the cell cycle are mediated by changes in antioxidant enzyme expression. Aim 3: Determine if antioxidant enzyme mediated alterations in progression from GI to S are caused by changes in the redox regulation of cyclin D1 expression. A mechanistic evaluation of intracellular redox environment and cell cycle progression could lead to a better understanding of normal and aberrant cellular proliferation. Since proliferative disorders are central to a variety of human pathophysiological conditions including normal tissue injury as well as tumor cell response during cancer therapy, results obtained from completion of the studies in this proposal could provide a biochemical rationale for manipulating cell proliferation to improve outcome.