Ttoxicity analyses and therapeutic modification of the anti-cancer drug camptothecin

结直肠癌（CRC）是德国第二大诊断癌症，每年导致3万人死亡。一般来说，结直肠癌的发生是环境因素和遗传易感性相互作用的结果。细胞防御系统在潜在致癌物质的解毒和癌症预防中起着至关重要的作用。UDP-glucuronosyltransferases （UGT）作为细胞防御机制的一部分，催化对致癌物和药物等外源物质的解毒。依临床情况而定，伊立替康可用于单药治疗或与其他细胞抑制剂（FOLFIRI）联合治疗转移性结直肠癌。20-30%的治疗患者出现严重副作用，如腹泻和白细胞减少（高达世卫组织第4级），属于剂量限制性毒性，影响伊立替康的治疗和治愈潜力。普遍表达的羧酸酯酶催化伊立替康转化为其活化但毒性更大的代谢物SN38。ugt的糖醛酸化作用导致SN38失活并通过胆汁和尿液消除。在一些研究中，UGT1A1基因（UGT1A1*28）的启动子突变与伊立替康治疗期间严重副作用的发生率增加有关。然而，携带该基因型的患者中约有50%患有严重的副作用，这表明进一步的因素可能在预测腹泻和白细胞减少方面发挥作用。105例伊立替康治疗患者的基因分型显示，UGT1A7基因（UGT1A7*3）的3种不同多态性与UGT1A1*28变异的组合是伊立替康毒性发生的可靠预测因子。在此背景下，我们想研究snp介导的葡萄糖醛酸化活性降低是否可以通过适当的、无毒的ugt1a诱导剂来补偿，并可能导致伊立替康相关毒性的降低。在这个项目中，需要分析ugt1a -活化剂咖啡对伊立替康治疗期间副作用的发生和严重程度的影响。因此，采用一种人源化转基因小鼠系，将上述ugt1a单倍型作为转基因基因携带。结果与第二种携带野生型人类UGT1A基因位点的小鼠系进行了比较。此外，应该分析在伊立替康治疗期间的性别差异，为尚未建立的性别特异性治疗策略提供潜在的基础。

Colorectal cancer (CRC) is he second most diagnosed cancer in Germany leading to death of 30000 people per year. Generally, development of CRC is the outcome of interactions between environmental factors and genetic predisposition. The cellular defence system plays an essential role in the detoxification of potentially carcinogenic xenobiotics and consequently in cancer prevention. UDP-glucuronosyltransferases (UGT), as a part of the cellular defence mechanisms, catalyze the detoxification of xenobiotic substances like carcinogens and drugs.Irinotecan is used, depending on the clinical context, in a monotherapy or in combination with other cytostatic agents (FOLFIRI) for the treatment of metastatic CRC. 20-30% of the treated patients suffer from serious side effects like diarrhoea and leucopenia (up to WHO grade 4) representing the dosis limiting toxicity which affects the therapeutic and curative potential of irinotecan. Ubiquitous expressed carboxylesterases catalyze the conversion of irinotecan to its activated but also more toxic metabolite SN38. Glucuronidation by UGTs leads to inactivation and elimination of SN38 via bile and urine. In several studies, a promoter mutation in the UGT1A1 gene (UGT1A1*28) was associated with increased occurrence of serious side effects during irinotecan therapy. However, approximately 50% of the patients carrying this genotype suffered from serious side effects indicating that further factors may play a role in the prediction of diarrhoea and leucopenia. Genotyping of 105 irinotecan treated patients revealed that only the combination of 3 different polymorphisms in the UGT1A7 gene (UGT1A7*3) together with the UGT1A1*28 variant is a reliable predictor for the occurrence of irinotecan-toxocity. Against this background we want to investigate if the SNP-mediated reduced glucuronidation activity can be compensated by appropriate, non-toxic UGT1A-inducers and potentially leads to reduction of irinotecan associated toxicity. Within this project, the effects of the UGT1A-activator coffee on the occurrence and the severity of side effects during irinotecan-treatment should be analyzed. Therefore, a humanized transgenic mouse line is used which carries the above mentioned UGT1A-haplotype as a transgene. The results are compared to those of a second mouse line which carries the human UGT1A gene locus in the wild type form. Additionally, gender specific differences during a coffee attended irinotecan-therapy should be analyzed potentially offering fundamentals for not yet established gender specific therapeutic strategies.