Impact of uracil DNA glycosylase on lung cancer cell sensitivity to pemetrexed

描述（由申请人提供）：耐药性和剂量限制性毒性是治疗人类癌症的主要障碍。通过将当前的抗癌药物与肿瘤增敏剂相结合，可以实现改善的全身性癌症治疗。肿瘤对化疗的敏感性受多种因素影响，包括识别和修复抗癌药物引起的DNA损伤。培美曲塞是一种用于治疗人肺癌和间皮瘤的叶酸拮抗剂。培美曲塞方案的成功受到剂量限制性骨髓抑制和获得性耐药的影响。在肿瘤细胞内，培美曲塞通过抑制参与从头胸苷生物合成的酶引起基因组尿嘧啶掺入。由尿嘧啶DNA糖基化酶（UDG）启动的碱基切除修复（BER）主动识别并从基因组中去除错误掺入的尿嘧啶。该提案将利用肺癌细胞系解决在理解UDG在培美曲塞敏感性中的作用方面的差距。使用该模型，我们将阐明以下假设：培美曲塞治疗通过参与DNA损伤反应信号传导（AIM 1）的转录因子调节细胞核UDG启动子诱导UDG表达。在AIM 2中，我们将建立UDG-/-肺癌细胞，以解决UDG表达缺失使肺癌细胞对培美曲塞敏感的假设。最后，在AIM 3中，我们将使用候选UDG抑制剂来评价抑制UDG活性可增强培美曲塞细胞毒性的假设。本文提出的研究将极大地扩展我们对UDG响应于DNA损伤的调节以及培美曲塞诱导的尿嘧啶蓄积对癌细胞毒性的影响的知识，以及评估UDG靶向改善培美曲塞疗效的潜力。 公共卫生相关性：本提案的目的是确定DNA修复蛋白UDG的表达和活性对肺癌对培美曲塞敏感性的影响。我们建议通过使用肺癌细胞系来研究培美曲塞处理的细胞中UDG表达的调节因子。我们还将开发稳定的UDG敲除肺癌细胞系，并利用UDG活性的小分子抑制剂来评估UDG表达和活性降低对培美曲塞敏感性的影响。

DESCRIPTION (provided by applicant): Drug resistance and dose-limiting toxicities are major obstacles in the treatment of human cancers. Improved systemic cancer therapy can be achieved by combining current anti-cancer drugs with tumor sensitizing agents. Tumor sensitivity to chemotherapy is influenced by several factors, including recognition and repair of the DNA damage caused by anti-cancer agents. Pemetrexed is an antifolate used in the treatment of human lung cancers and mesothelioma. The success of pemetrexed regimens is influenced by dose-limiting myelosuppression and the development of acquired resistance. Within tumor cells, pemetrexed causes genomic uracil incorporation through inhibition of enzymes involved in de novo thymidine biosynthesis. Base excision repair (BER), initiated by uracil DNA glycosylase (UDG), actively recognizes and removes misincorporated uracil from the genome. This proposal will utilize lung cancer cell lines address gaps in understanding of the role of UDG in pemetrexed sensitivity. Using this model we will address the hypothesis that UDG expression is induced in response to pemetrexed treatment via regulation of the nuclear UDG promoter by transcription factors involved in DNA damage response signaling (AIM1). In AIM 2, we will establish UDG-/- lung cancer cells to address the hypothesis that loss of UDG expression sensitizes lung cancer cells to pemetrexed. Lastly, in AIM3, we will use candidate UDG inhibitors to evaluate the hypothesis that inhibition of UDG activity can potentiate pemetrexed cytotoxicity. The studies proposed herein will greatly expand our knowledge of the regulation of UDG in response to DNA damage and the impact of pemetrexed- induced uracil accumulation on cancer cell toxicity, as well as evaluate the potential for UDG targeting to improve pemetrexed efficacy. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to determine the impact of expression and activity of the DNA repair protein, UDG, on lung cancer sensitivity to pemetrexed. We propose to do this by using lung cancer cell lines to study the regulators of UDG expression in cells treated with pemetrexed. We will also develop stable UDG knockout lung cancer cell lines as well as utilize small molecule inhibitors of UDG activity to evaluate the impact of decreased UDG expression and activity on pemetrexed sensitivity.