基于结构的新型血清白蛋白改造及其应用

血清白蛋白作为人体血浆中含量最高和长半衰期的蛋白，具有酯酶活性，能结合体内脂肪酸和体外药物。作为血浆容量扩充剂，白蛋白主要从献血者血浆中获取，重组的血清白蛋白至今仍然未进入临床应用。而作为药物载体，白蛋白虽然有成功临床应用的例子，但其自身的局限性：1）对药物的载药量有限；2）对肿瘤缺乏明确的靶向性等，限制了其广泛应用。本申请针对这些科学问题，将开展基于白蛋白晶体结构的白蛋白内部（而不是表面）氨基酸的改造，构建高载药量、无免疫源性的新型重组白蛋白；将筛选出针对4种靶标的靶向拟抗体并将其与新型白蛋白融合制备成靶向型白蛋白；将用这类新型白蛋白装载药物，对靶向型白蛋白与药物或其靶标复合物进行三维结构研究，并评价这些载药靶向白蛋白的体内和体外的抗肿瘤效果。申请人长期开展白蛋白研究。本项目是多学科交叉和多技术的融合，是基础和应用的结合，有较强的可行性，有望对白蛋白这个热点研究领域做出重大推进作用。

Human serum albumin (HSA) has the highest abundance and longest half-life in plasma, binds and transports fatty acids, and has esterase activity. HSA has important applications in clinic for maintaining osmotic pressure and others. Clinic-used HSA is still derived from blood of healthy donors; the recombinant HSA (rHSA) has not been used in clinic yet. HSA is also used a carrier for external drugs to promote drug absorption and transportation in plasma, but is restrained by a number of factors, including limited loadability to cargo drug and limited targeting capability to tumors. In this application, we propose to tackle these problems by engineering HSA, based on its crystal structure, at its interior (but not surface) amino acid residues to avoid immunogenicity. We aim to generate new recombinant HSA with high drug loadability. We will also identify new peptide-based targeting agents to bind to 4 tumor targets, and fuse the coding DNA of these peptide binders with HSA to generate recombinant HSA fusion protein capable to binding to target and to having high drug loadability. We will then study the crystal structure new targeting rHSA and its complex with drug cargo or targeting proteins. Next, we will evaluate the efficacy of the new targeting rHSA as drug carrier in cells and in animal models. This is an interdisciplinary proposal applying an array of techniques to undertake the important scientific questions. The applicant for this proposal has long experience in the field. The proposal is also backed by promising preliminary results. Thus, this proposal has high chance of success and will have major impact to the field of HSA.