Studies On HPV16、18E6E7Based Cancer Therapeutic Vaccines

Cervical cancer is the second leading cause of cancer death among womenworldwide. In developing countries, cervical cancer is the most common cancer inwomen. Traditional treatments of cervical cancer such as surgery, radiotherapy andchemotherapy have their own limitations. Human papillomavirus is a majoretiological factor in cervical cancers, nearly all cervical cancers are attributable toinfection with a virus belonging to the high-risk subset of human papillomavirustypes, such as HPV16and18. Therefore, in this study two subjects were carried outaccording to therapeutic vaccine. One is the investigation of immunogenicity andantitumor response of therapeutic vaccines for cervical cancer with HPV16E6E7asantigens, another is the testing of carcinogenicity of the optimized and recombinantHPV18E6E7gene.E6and E7are the major onco-proteins of high-risk HPVs. The E6protein canbind and induce the degradation of P53and destroy the normal control of the cellcycle, While the E7protein can bind and induce the degradation of the pRb proteinand hence the pRb lost it ability as an anti-oncogene. Since E6and E7are consistentlyexpressed in HPV infected tissues but absent in normal tissues, they represent idealtherapeutic targets for immunotherapy of cervical cancer.In the research of immunogenicity and antitumor response of therapeuticvaccines, a recombinant adenoviruses based and a DNA based vaccine containingoptimized mutant fused HPV16E6E7gene were constructed. The adenovirusesexpressing wide type and mutant E6E7protein were used to transduce murine DCs todevelop therapeutic vaccine. ELISPOT assay were used to detect the cellular immuneresponses after C57BL/6mice were immunized. In order to detect antitumorresponses, preventing tumor formation test were carried out. Our data indicated thatthe HPV16E6E7primed DC vaccines had good immunogenicity and antitumorresponse. In the testing of carcinogenicity of the optimized and recombinant gene, theoptimized fusion gene HPV18E6E7(HPV18-E6E7-1) was constructed according togenetic codon usage in human gene. Meanwhile, for safety future clinical application,the mutant of HPV18-E6E7fusion gene was generated by site-directed mutagenesis.The results suggested that the optimized mutant fused HPV18-E6E7genesconstructed in this work (HPV18-E6E7-3&HPV18-E6E7-4) lost the transformationcapability to NIH3T3cells and tumorigenicity in BALB/c Nud mice, which indicatethat the optimized mutant fused genes are safe.