ROLE OF DUTPASE EXPRESSION IN CANCER CHEMOTHERAPY

四十多年来，胸苷酸代谢一直是一个重要的研究领域。 是广泛使用抗癌剂的重要生物化学靶标。抑制剂 如氟嘧啶和抗叶酸剂诱导严重的 TTP池耗尽导致核苷酸池失衡和细胞杀伤 这一过程被称为“无胸腺嘧啶死亡”。“调查所涉 这一过程的机制表明，尿嘧啶-DNA代谢异常可能是 DNA损伤和细胞杀伤的重要介质。广泛、长期 本研究的目的是：1）阐明异常dUTP的作用 代谢作为化学治疗诱导的细胞杀伤的分子机制 靶向胸苷酸生物合成的药物; 2）为了更好地了解 参与dUTP代谢的关键酶在调节化疗敏感性中的作用。 在这项研究中，申请人提出了一种无胸腺嘧啶的机制分析。 使用过表达该酶的人类结肠癌细胞系死亡 脱氧尿苷三磷酸核苷酸水解酶（dUTR）。杜特尔特催化 dUTP水解形成dUMP和PPi，从而从DNA中消除dUTP 生物合成途径申请人假设dUTR的过度表达 对抗FUdR治疗的细胞毒性作用， dUTP池。尽管有大量证据表明尿嘧啶DNA 代谢可能是介导细胞毒性的关键因素， 未进行生化研究以阐明人dUTR亚型的作用 表达调节化疗敏感性。拟议的研究旨在 尿嘧啶-DNA介导的细胞毒性的关键机制标志与 氟脱氧尿苷诱导的细胞死亡。具体目标1研究了 dUTR异构体的过度表达作为对FUdR诱导的耐药机制 细胞毒具体目标2研究了生物化学之间的相关性 异常尿嘧啶-DNA代谢和对FUdR的化学敏感性的终点。 特异性目的3研究了dUTR亚型表达的意义， 预测患者对基于氟尿嘧啶的化疗的反应， 转移性结肠癌的存活率。更好地理解 尿嘧啶-DNA代谢异常介导无胸腺嘧啶死亡不仅 提高我们对这些药物作用的分子机制的认识， 重要的化学治疗剂，而且还提供了对新的和改进的 治疗策略。

For more than forty years, thymidylate metabolism has been an important biochemical target for widely utilized anti-cancer agents. Inhibitors of this pathway such as the fluoropyrimidines and antifolates induce a severe depletion of TTP pools resulting in nucleotide pool imbalance and cell killing through a process termed "thymineless death." Investigation of the underlying mechanisms of this process suggest that aberrant uracil-DNA metabolism may be an important mediator of DNA damage and cell killing. The broad, long-term objectives of this proposal are: 1) to elucidate the role of aberrant dUTP metabolism as a molecular mechanism of cell killing induced by chemotherapeutic agents that target thymidylate biosynthesis and; 2) to better understand the role of key enzymes involved in dUTP metabolism in modulating chemosensitivity. In this study, the applicants propose a mechanistic analysis of thymineless death using human colon cancer cell lines that over express the enzyme deoxyuridine triphosphate nucleotide hydrolase (dUTPase). dUTPase catalyzes the hydrolysis of dUTP to form dUMP and PPi, thereby eliminating dUTP from the DNA biosynthetic pathway. The applicants hypothesize that dUTPase over-expression counters the cytotoxic effect of FUdR treatment by limiting the expansion of dUTP pools. Although there is significant evidence suggesting that uracil-DNA metabolism may be a critical factor in mediating cytotoxicity, there have been no biochemical studies performed to clarify the role of human dUTPase isoform expression in modulating chemosensitivity. The proposed studies are designed to correlate key mechanistic hallmarks of uracil-DNA mediated cytotoxicity with cell death induced by fluorodeoxyuridine. Specific Aim 1 investigates the role of dUTPase isoform over-expression as a mechanism of resistance to FUdR-induced cytotoxicity. Specific Aim 2 investigates the correlation between biochemical endpoints of aberrant uracil-DNA metabolism and chemosensitivity to FUdR. Specific Aim 3 investigates the significance of dUTPase isoform expression in predicting patient response to fluoropyrimidine-based chemotherapy and overall survival in metastatic colon cancer. A better understanding of the role of aberrant uracil-DNA metabolism in mediating thymineless death should not only enhance our knowledge of the molecular mechanism of drug action of these important chemotherapeutics, but also provide insight into novel and improved treatment strategies.