基于黑猩猩腺病毒AdC68的溶瘤腺病毒系统及其抑瘤机制的研究

Oncolytic adenoviruses have widely been used to treat tumor in recent years, and the type of adenoviruses that are most widely engineered into adenoviruses is based on human adenoviruses AdHu5. However, the preexisting anti-AdHu5 neutralizing antibodies could reduce the anti-tumor efficacy of oncolytic adenoviruses derived from AdHu5. In addition, the interaction between the Hexon protein of adenoviruses and blood coagulation factor X lead to the accumulation of adenoviruses in liver through FX receptor widely expressed in hepatocytes. The expression of CAR receptor in a wide range of tissues results in in vivo transduction of nontarget tissues. Chimpanzee adenoviruses do not circulate in human beings, and thus there are not anti-chimpanzee adenovirus neutralizing antibodies in human populations. Previous researches have revealed that Anti-AdHu5 immune could not influence infection of chimpanzee adenoviruses. Moreover, the complexes of Hexon proteins and blood coagulation factor X are unstable, leading to less accumulation of adenoviruses in liver. In conclusion, chimpanzee adenoviruses are an ideal oncolytic adenoviral platform which could tackle some of drawbacks of Adhu5. In this study, we develop the oncolytic adenovirus system based on chimpanzee adenoviruses AdC68. Using the oncolytic adenovirus system AdC68, we construct a novel oncolytic adenovirus AdC7-IRES-ΔE3 in which tumor-specific IRSE from human rhinovirus 2 is inserted into the 5’NTR of E1A mRNA to control the specific translation of E1A in gliomas, thus enabling AdC7-IRES-ΔE3 to conditionally replicate in gliomas. In order to increase tropism for gliomas, peptides pK7, which can selectively bind to heparan sulfate receptors overexpressed in glioma cells, are inserted into fiber genes, forming oncolytic adenoviruses AdC7-IRES-ΔE3-pK7 that could more effectively target gliomas than AdC7-IRES-ΔE3. Furthermore, we investigate the anti-tumor efficacy of AdC7-IRES-ΔE3-pK7 and also the mechanism behind the anti-tumor efficacy.

溶瘤腺病毒近年来成为肿瘤治疗领域的热点。基于人5型腺病毒（AdHu5）的溶瘤腺病毒具有天然缺陷：人群普遍存在中和抗体；AdHu5的Hexon蛋白与血液中的凝血因子X（FX）结合，导致该腺病毒在肝脏累积；AdHu5的肿瘤靶向差。黑猩猩腺病毒在人群中不流行，也不会被抗腺病毒AdHu5的抗体所中和。而且黑猩猩腺病毒的Hexon蛋白不与FX结合。因此，黑猩猩腺病毒是一种理想的溶瘤病毒载体平台。在本项目中，我们将研发基于黑猩猩腺病毒AdC68的新型溶瘤腺病毒系统。将肿瘤特异的IRES插入到E1A mRNA的5端非翻译区，从而使其在肿瘤细胞中特异地表达，利用这一原理构建条件复制型腺病毒AdC7-IRES-ΔE3，然后在fiber蛋白中插入与硫酸肝素蛋白聚糖（HSGPs）特异结合的多肽pK7以增强其对肿瘤细胞的靶向性，从而获得一种高靶向性的新型溶瘤腺病毒，并研究该新型溶瘤腺病毒的溶瘤效果和溶瘤机制。