Metabolic Oxidative Stress in Human Cancer Cells

自20世纪20年代以来，已经观察到癌细胞（相对于正常细胞）表现出增加的细胞凋亡。 糖酵解和戊糖循环活动的速率以及呼吸速率略有下降，但 这对癌症治疗的意义尚不清楚。最近的研究表明，葡萄糖剥夺 相对于正常细胞，在人癌细胞中优先诱导细胞毒性和氧化应激 [附录1]。线粒体被假设为葡萄糖代谢过程中产生氧化剂的场所 剥夺如果这是普遍正确的，葡萄糖剥夺诱导的氧化应激可能代表一种缺陷， 在肿瘤细胞中，线粒体代谢可用于改进癌症治疗。的 目前的提议将检验线粒体产生活性氧物质（ROS;即， 超氧化物和过氧化氢）介导人癌细胞对葡萄糖的敏感性增加 剥夺诱导的代谢氧化应激，相对于正常细胞。具体目标1将使用 电子传递链阻断剂（即，抗霉素A、粘噻唑和鱼藤酮），如果是完整的人癌细胞 (or分离的线粒体）证实了通过线粒体电子传递的ROS产生的改变 链复合物I、II和/或III，其有助于增加对葡萄糖剥夺诱导的 氧化应激，相对于正常细胞。特异性目标2将确定rho（0）癌细胞是否缺乏 功能性线粒体电子传递链表明对葡萄糖剥夺的敏感性改变- 诱导的细胞毒性和氧化应激，相对于含有全功能电子的亲代rho（+）细胞 运输链。特异性目的3将使用腺病毒载体以及稳定转染的细胞来确定 线，如果过度表达的抗氧化酶，使超氧化物和过氧化氢（即， 过氧化氢酶，超氧化物歧化酶）能够改变葡萄糖剥夺的生物学效应， 癌细胞具体目标4将确定2-脱氧-d-葡萄糖是否能够模拟葡萄糖的作用 在目标1-3中看到的剥夺。长期目标是提供一个严格的机械理解， 癌细胞对葡萄糖剥夺诱导的氧化应激的不同敏感性， 根据正常人氧代谢的差异， vs.癌细胞

Since the 1920's it has been observed that cancer cells (relative to normal cells) demonstrate increased rates of glycolysis and pentose cycle activity as well as slightly decreased rates of respiration but the significance of this to cancer therapy is unclear. Recent studies have shown that glucose deprivation preferentially induces cytotoxicity and oxidative stress in human cancer cells, relative to normal cells [Appendix 1]. Mitochondria have been hypothesized to be the site of prooxidant production during glucose deprivation. If this were generally true, glucose deprivation-induced oxidative stress could represent a defect in tumor cell mitochondrial metabolism amenable to manipulations designed to improve cancer therapy. The current proposal will test the hypothesis that mitochondrial production of reactive oxygen species (ROS; ie., superoxide and hydrogen peroxide) mediates the increased susceptibility of human cancer cells to glucose deprivation-induced metabolic oxidative stress, relative to normal cells. Specific Aim 1 will determine using electron transport chain blockers (i.e., antimycin A, myxothiazol, and rotenone), if intact human cancer cells (or isolated mitochondria) demonstrate alterations in ROS production by mitochondrial electron transport chain Complexes I, II, and/or III that contribute to increased susceptibility to glucose deprivation-induced oxidative stress, relative to normal cells. Specific Aim 2 will determine if rho(0) cancer cells, deficient in functional mitochondrial electron transport chains demonstrate altered susceptibility to glucose deprivation- induced cytotoxicity and oxidative stress, relative to parental rho(+) cells containing fully functional electron transport chains. Specific Aim 3 will detemine using adenoviral vectors as well as stably transfected cell lines, if over expession of antioxidant enzymes that scavenge superoxide and hydrogen peroxide (ie., catalase, superoxide dismutases) are capable of altering the biological effects of glucose deprivation in cancer cells. Specific Aim 4 will determine if 2-deoxy-d-glucose is capble of mimicing the effects of glucose deprivation seen in Aims 1-3. The long-term goal is to provide a rigourous mechanistic understanding of the differential susceptibility of cancer cells to glucose deprivation-induced oxidative stress for the purpose of developing combined modality cancer therapy based on differences between oxygen metabolism in normal vs. cancer cells.