【作者】 张小平；

【导师】 钱旻；

【作者基本信息】 华东师范大学 ， 生物化学与分子生物学， 2006， 硕士

【摘要】 原发性肝癌在世界范围分布较广泛，是严重影响我国人民健康的疾病之一。随着现代医学影像技术的发展，肝癌的诊断率和准确性大幅度地提高了，但是包括基因工程技术在内的现代分子生物学技术的发展在肝癌临床治疗中的应用和对预后的提高上几乎是微乎其微，传统的肿瘤治疗方法在肝癌的治疗中仍占据绝对主导地位。随着肝脏外科技术的改进，肝癌的手术切除率和治疗效果也不断提高，手术死亡率随之降低，但手术治疗也有其特有的局限性，尤其在肝癌的中晚期病人中，往往已不能采取手术治疗的方法。另外常规的放射治疗和化学治疗等方法也存在种种不足和缺陷，如肿瘤的耐药性以及严重的副作用。因此研究肝癌的诊断与治疗新方法具有十分重要的理论与现实意义。 免疫毒素是近年来新兴的一种肿瘤导向治疗方法。它利用抗肿瘤单抗与肿瘤细胞的特异性结合，将生物毒素与抗体偶联，定向攻击肿瘤细胞，而对正常组织的杀伤较小，故被形象地称为“生物导弹”。免疫毒素的细胞毒作用主要源于各种生物毒素，它们的生物活性较高、毒性较大。我们采用的毒素是改造过的绿脓杆菌外毒素PE40KDEL，即去除原毒素中的细胞非特异性结合域并进行了氨基酸突变以增加其细胞毒性，使获得的毒素蛋白在丧失了非特异性细胞毒性的同时增加了对靶细胞的毒性，因而具有很高的应用价值。目前，免疫毒素已在乳腺癌、黑色素瘤、白血病治疗和体外骨髓移植等方面获得了一定的进展，有不少制剂也进入临床Ⅰ／Ⅱ期试验阶段。但由抗体介导的免疫毒素在体内的应用还没有人们预期的那么有效，其原因主要在于：一，鼠源性抗体进入人后会产生人抗鼠的抗体(HAMA)，引起人体过敏反应；二，抗体分子量大，在体内组织的穿透能力差；三，目前多数的小分子抗体自身的亲和力较低，特异性不高；四，肿瘤自身抗原表达的不均一性及抗原的调变，可以逃避偶联药物与之的结合，从而影响治疗效果。随着小分子多肽研究的进一步深入，尤其是随着噬菌体肽库技术的发展，小分子导向载体的发现和应用为导向治疗提供了新途径。 本课题拟从噬菌体展示肽库中筛选能与肝癌细胞发生特异性结合的噬菌体肽(称为肝癌特异性结合肽，liver cancer adhesion peptide，LAP)，并与改造过的绿脓杆菌外毒素PE40KDEL进行基因重组，旨在得到特异性高，杀伤力强的新更多还原

【Abstract】 Human hepatocellular carcinoma(HCC) is one of the most common cancers worldwide and remains one of leading causes of death from cancer in China. With the development of medical imaging technology, the diagnosis has been more precise ,but the application of molecular biological technology in the treatment of HCC is very little. The conventional approaches include surgery, chemotherapy, and radiotherapy take up the first status in cancer cure。 but most of human cancers remains incurable and prognosis remains poor. It is clear that new therapeutic approaches are urgently needed for those patients who have unresectable cancer at the time of diagnosis.Differentiation antigens, hormones, growth factor receptors, and viral antigens are expressed on the surface of a variety of malignant and dysfunctional cells in humans, which is the base of targeted therapy. Targeted therapy has become a major part of biotherapy of cancer after the conventional therapeusis. Over the past years, monoclonal antibodies have attracted enormous interest as targeted therapeutics, especially advances in immunoconjugate technology have revitalized the "magic bullet" concept of immunotherapeutics for the treatment of cancer. More importantly, antibody fusion proteins such as immunotoxins which were derived by coupling toxins to scFv antibody fragments using recombinant DNA technology have greatly increased the potential for cancer therapeutic oppottunities. Immunotoxin is composed of "bullet" and vector. "Bullet" is creature toxin, derived from plant and bacteria, which is catalyzed by enzymes. Once recombinant immunotoxins bind to receptors on cancer cells, the toxin enters and kills the cells. Pseudomonas exotoxin A enzymatically ADP-ribosylates elongation factor 2, restrain protein synthesis. Presently, some achievements of immunotoxins have been made in breast cancer,更多还原