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

结直肠癌是德国第二大确诊癌症，每年导致30000人死亡。一般说来，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外源物质的解毒中发挥着至关重要的作用，从而在癌症预防中发挥着重要作用。UDP-葡萄糖醛酸基转移酶(UGT)作为细胞防御机制的一部分，催化致癌物和药物等外来物质的解毒。伊立替康可根据临床情况单独使用或与其他细胞抑制剂(FOLFIRI)联合用于转移性结直肠癌的治疗。接受治疗的患者中有20%-30%出现严重的副作用，如腹泻和白细胞减少症(最高可达WHO 4级)，这是一种限制毒性的药物，影响了伊立替康的治疗和治疗潜力。广泛表达的羧酸酯酶催化伊立替康转化为其活性但毒性更强的代谢物SN38。UGTS的葡萄糖醛酸化作用导致SN38失活并通过胆汁和尿液消除。在几项研究中，UGT1A1基因的启动子突变(UGT1A1*28)与伊立替康治疗期间严重副作用的增加有关。然而，大约50%的携带该基因的患者出现了严重的副作用，这表明进一步的因素可能在腹泻和白细胞减少症的预测中发挥作用。105例接受伊立替康治疗的患者的基因分型显示，只有UGT1A7基因(UGT1A7*3)的3种不同多态和UGT1A1*28变异相结合才能可靠地预测伊立替康中毒的发生。在此背景下，我们想要研究SNP介导的降低的葡萄糖醛酸化活性是否可以被适当的、无毒的UGT1A诱导剂补偿，并可能导致伊立替康相关毒性的降低。在这个项目中，应该分析UGT1A激活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，采用人源化的转基因小鼠品系，携带上述单倍型UGT1a作为转基因。结果与第二个携带人类UGT1A基因的野生型小鼠品系的结果进行了比较。此外，应该分析伊立替康咖啡治疗期间的性别差异，这可能会为尚未确定的性别特定治疗策略提供基础。

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.