Immunization with mutant HPV16 E7 protein inhibits the growth of TC-1 cells in tumor-bearing mice

Genetic variability of human papillomavirus type 39 based on E6, E7 and L1 genes in Southwest China

Background

Human papillomavirus type 39 associated with genital intraepithelial neoplasia and invasive cancers, has a high prevalence in Southwest China. HPV E6, E7 are two main papillomavirus oncoproteins, closely relate to the function of HPV immortalization, cell transformation, and carcinogenesis. L1 is the major capsid protein, can reflect the replication status of the virus in cells and the progression of cervical lesions. The purpose of this study is to reveal the prevalence of HPV 39 and the genetic polymorphisms of HPV39 based on E6, E7 and L1 gene in southwest China.

Methods

Cell samples were collected by cervical scraped for HPV detecting and typing, and HPV39 positive samples were selected out. Important E6, E7 and L1 genes of HPV39 were sequenced and analyzed for the study of HPV39 genetic polymorphisms. Phylogenetic trees were constructed by Maximum-likelihood and Kimura 2-parameters methods in Molecular Evolutionary Genetics Analysis version 6.0. The selection pressures of E6, E7 and L1 genes were estimated by Datamonkey web server. The secondary and three-dimensional structure of HPV39 E6, E7 proteins were created by sopma server and SWISS-MODEL software.

Results

344 HPV39 positive samples were selected from 5718 HPV positive cell samples. Among HPV39 E6-E7 sequences, 20 single nucleotide mutations were detected, including 10 non-synonymous and 10 synonymous mutations; 26 single nucleotide mutations were detected in HPV39 L1 sequences, including 7 non-synonymous and 19 synonymous mutations respectively. 11 novel variants of HPV39 E6-E7 (5 in E6 and 6 in E7) and 14 novel variants of HPV39 L1 were identified in this study. A-branch was the most frequent HPV39 lineage in southwest China during our investigation. Selective pressure analysis showed that codon sites 26, 87, 151 in E6 and 75, 180, 222, 272, 284, 346, 356 in L1 were positively selected sites, as well as codon sites 45, 138, 309, 381 were negative selection sites in L1 gene, E7 has neither positive selection sites nor negative selection sites. A certain degree of secondary and three-dimensional structure dislocation was existed due to the non-synonymous mutations.

Conclusions

Amino acid substitution affected the secondary and three-dimensional structure of HPV39, and resulting in the differences of carcinogenic potential and biological functions as well as the immune response due to the antigen epitopes difference, the antigen epitopes with stronger adaptability in Southwest will be screened out based on the above research results for the later vaccine development. And gene polymorphism of HPV39 in Southwest China may improve the effectiveness of clinical test and vaccine design, specifically for women in Southwest China.

Co-administration of 2'3'-cGAMP STING activator and CpG-C adjuvants with a mutated form of HPV 16 E7 protein leads to tumor growth inhibition in the mouse model

Persistent infection with high-risk genotypes of human papillomavirus (HPV) is the leading cause of cervical cancer. The HPV oncoprotein E7 is constitutively expressed in cervical cancer and considered as an essential target for tumor-specific immunity. The goal of this study was to develop a candidate therapeutic vaccine based on the mutated E7 protein that had possibly reduced transformation capacity while was able to elicit a robust immune response. Therefore, the mutant type of HPV 16 E7 (E7GRG) protein was recombinantly expressed in E. coli. The protein was then purified and formulated with 2’-3’cGAMP CDN and/or CpG-C ODN adjuvants and subcutaneously injected to female C57BL/6 mice. To evaluate the immunogenic response, lymphocyte proliferation, secretion levels of IFN-γ and IL-4 cytokines, granzyme B level, and total IgG and subclasses of IgG antibody were measured. The anti-tumor activity was evaluated in tumor-harboring C57BL/6 mice. The highest rate of cell proliferation, IFN-γ and granzyme B levels, and amount of IgG antibody were found in mice group that were injected by E7GRG + 2′-3′cGAMP + CpG-C. Therapeutic immunization with E7GRG + 2′-3′cGAMP + CpG-C also significantly suppressed TC-1 tumor growth in mice. In conclusion, the results demonstrated that E7GRG + 2′-3′cGAMP + CpG-C induced strong cell-mediated and humoral immune responses that resulted in inhibition of tumor in mouse model.

Targeted biological effect of an affitoxin composed of an HPV16E7 affibody fused with granzyme B (ZHPV16E7-GrB) against cervical cancer in vitro and in vivo

BACKGROUND

High risk type 16 of human papillomavirus (HPV16) is associated with 50% of cervical cancer, for which reliable targeted therapies are lacking. HPV early protein 7 (E7) is an oncoprotein responsible for cell malignant transformation. In our previous work, a highly specific affibody targeting HPV16E7 (ZHPV16E7) was developed.

OBJECTIVE

In order to improve the targeted therapeutic effect, the present study prepared an affitoxin consisting of ZHPV16E7 fused with granzyme B (GrB), namely, ZHPV16E7-GrB, and evaluated its targeting action in vitro and in vivo.

METHODS

The ZHPV16E7-GrB fusion protein was produced in a prokaryotic expression system. The targeted binding properties of the ZHPV16E7-GrB to the HPV16E7 were confirmed by immunofluorescence assay (IFA) in cervical cancer cell lines, by immunohistochemical assay (IHA) in cervical cancer tissue from clinical specimens and by near-infrared imaging in tumour-bearing mice. The anti-tumour effect on both cervical cancer cells in vitro and tumour-bearing mice in vivo were further evaluated.

RESULTS

A 34-kDa ZHPV16E7-GrB fusion protein was produced in E. coli and displayed corresponding immunoreactivity. IFA revealed that ZHPV16E7-GrB bound specifically to HPV16-positive TC-1 and SiHa cells. IHA showed that ZHPV16E7-GrB also bound specifically to HPV16-positive clinical tissue specimens. In addition, the near-infrared imaging results showed that ZHPV16E7-GrB was enriched in tumour tissues. Moreover, both the ZHPV16E7-GrB affitoxin and ZHPV16E7 affibody (without GrB) significantly reduced the proliferation of cervical cancer cells in vitro and tumour-bearing mice in vivo, and the antiproliferative effect of ZHPV16E7-GrB was higher than that of the ZHPV16E7 affibody.

CONCLUSIONS

The affitoxin by coupling the affibody with GrB is a promising targeted therapeutic agent with the dual advantages of the targeted affibody and the GrB cytotoxin.

Intranasal Therapeutic Peptide Vaccine Promotes Efficient Induction and Trafficking of Cytotoxic T Cell Response for the Clearance of HPV Vaginal Tumors

Human papillomavirus (HPV)-induced cancers continue to affect millions of women around the world, and the five year survival rate under the current standard of care for these cancers is less than 60% in some demographics. Therefore there is still an unmet need to develop an effective therapy that can be easily administered to treat established HPV cervical cancer lesions. We sought to investigate the potential of an intranasal HPV peptide therapeutic vaccine incorporating the combination of α-Galactosylceramide (α-GalCer) and CpG-ODN adjuvants (TVAC) against established HPV genital tumors in a syngeneic C57BL/6J mouse model. We obtained evidence to show that TVAC, delivered by the mucosal intranasal route, induced high frequencies of antigen-specific CD8 T cells concurrent with significant reduction in the immunosuppressive regulatory T cells and myeloid derived suppressor cells in the tumor microenvironment (TME), correlating with sustained elimination of established HPV genital tumors in over 85% of mice. Inclusion of both the adjuvants in the vaccine was necessary for significant increase of antigen-specific CD8 T cells to the tumor and antitumor efficacy because vaccination incorporating either adjuvant alone was inefficient. These results strongly support the utility of the TVAC administered by needle-free intranasal route as a safe and effective strategy for the treatment of established genital HPV tumors.

Development of multiepitope therapeutic vaccines against the most prevalent high-risk human papillomaviruses

Aim: Our goal was the development of DNA- or peptide-based multiepitope vaccines targeting HPV E7, E6 and E5 oncoproteins in tumor mouse model. Materials & methods: After designing the multiepitope E7, E6 and E5 constructs from four types of high risk HPVs (16, 18, 31 & 45) using bioinformatics tools, mice vaccination was performed by different homologous and heterologous modalities in a prophylactic setting. Then, anti-tumor effects of the best prophylactic strategies were studied in a therapeutic setting. Results: In both prophylactic and therapeutic experiments, groups receiving homologous E7+E6+E5 polypeptide, and heterologous E7+E6+E5 DNA prime/polypeptide boost were successful in complete rejection of tumors. Conclusion: The designed multiepitope constructs can be considered as promising candidates to develop effective therapeutic HPV vaccines.