Antioxidant Enzymes and Cell Cycle Checkpoint Pathways

氧化副产物产生的活性氧物种(ROS：超氧化物和过氧化氢) 能量代谢已被证明是生理信号过程的重要中介。这 该提案旨在检验ROS(即，超氧化物和过氧化氢)调节 通过对G1期细胞周期调节蛋白的氧化还原调节，从G1期进入S期。这 假说是基于我们的观察，在G！的末端有一个促氧化信号！法线的相位 成纤维细胞周期似乎是进入S期的刺激所必需的(癌症研究 63：2109-2117,2003)。此外，我们还发现抗氧化酶(磷脂)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)诱导人乳房发育迟缓 和前列腺癌细胞(自由基研究37：621-630,2003；癌基因，24：77-89,2005)。这些 观察表明，细胞周期的氧化还原调节可以在细胞之间提供一种机械联系 循环调节蛋白和氧化代谢过程是成功完成 每一个细胞周期时相。为了严格检验上述假设，本文提出了三个具体目标： 目标1：确定细胞内代谢超氧化物和过氧化氢的抗氧化酶 (锰超氧化物歧化酶、铜锌超氧化物歧化酶、过氧化氢酶和/或谷胱甘肽过氧化物酶)调节细胞周期进程 非恶性小鼠和人成纤维细胞从GI到S。 目标2：确定超氧化物和过氧化氢的稳态水平是否随着细胞的进展而波动 通过细胞周期的不同阶段，如果ROS在不同阶段之间的波动 细胞周期是通过抗氧化酶表达的变化来调节的。 目的3：确定抗氧化物酶介导的胃肠道疾病进展到S的改变是否由 细胞周期蛋白D1表达的氧化还原调节变化。 对细胞内氧化还原环境和细胞周期进程的机械评估可能会导致更好的 对正常和异常细胞增殖的理解。因为增殖性疾病是 人类各种病理生理状况，包括正常组织损伤和肿瘤细胞反应 在癌症治疗期间，完成本提案中的研究所获得的结果可以提供 控制细胞增殖以改善结果的生化原理。

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.