The effect of human papilloma virus type 16 E7 protein expression on growth of RMA cells in vitro and in vivo

Objective： The aim of this study was to study the effect of human papilloma virus （HPV） type 16 E7 protein ex- pression on growth of RMA cells in vitro and in vivo. Methods： The recombination vector pcDNA3.1-E7 carrying wild type HPV 16 E7 was identified by sequencing. The recombination vector pcDNA3.1-E7 was transfected into mouse lymphadenoma cell line RMA by liposome, and the monoclonal cells transfected stably were obtained by antibiotics G418 sieving and limiting dilution assay. RT-PCR method was used to detect the expression of HPV 16 E7 mRNA in RMA-E7 cells. The growth of RMA cells and RMA-E7 cells cultured in vitro was tested by Cell Count Kit-8. RMA-E7 cells and RMA cells were subcutaneously inoculated in syngeneic mice respectively, the tumor size was measured by sliding caliper twice a week, and the E7 protein expression in tumor tissue of mice was detected by Western blot after tumor formation. The kinetics of cytolytic activity of E7 specific T cells in tumor-bearing mice was measured by LDH kit. Results： Sequencing of recombination vector showed the target gene which was inserted into the recombinant was correct, and RMA-E7 cells expressing E7 protein stably were obtained by limited dilution assay. There were no obvious differences in morphous and growth velocity between RMA cells and RMA-E7 cells in vitro. RMA-E7 cells grew in syngeneic mice were significantly slower than RMA cells. The E7 protein was ex- pressed stronger in RMA-E7 cells in vivo than in vitro. The cytolytic ability of ET-specific CTL was activated at the early stage, reached the maximum at the middle stage, and lost at the end stage. RMA-E7 cells isolated from the tumor-bearing mice were more resistant to E7-specific CTL killing than RMA-E7 cells cultured in vitro. Conclusion： The E7 protein expression has no obvious influence on growth of RMA-E7 cells in vitro, and can suppress growth of RMA-E7 cells in vivo. The activity curve of E7 specific CTL approximately presents ＂bell＂ shape. The RMA-E7 cells grew in vivo had a high expression levels of E7 protein, and more resistant to E7-specific CTL killing than those cultured in vitro. The E7 protein expression in vivo not only initiates immune activation, but also induces immune tolerance.

HPV16E7-HSP70 Hybrid DNA Vaccine Induces E7-Specific Cytotoxic T Cells and Antitumor Immunity

Using human papillomavirus type 16 （HPV16） E7 as an antigen and Heat Shock Protein 70 as adjuvant, we constructed a DNA vaccine by linking HSP70 gene to E7^C91G; gene. Mice, after being immunized with E7^C91G;-HSP70, E7^C91G/HSP70, E7^C91G, and wild E7 DNA vaccines respectively, produced E7 specific CD8^＋ T-cell precursor frequencies of 280.33±2.52, 144.34±4.04, 164.34±5.13 and 82.33±3.51 respectively within every 1 × 10^5 mouse splenocytes. This proves that E7^C91G-HSP70 fusion vaccine can significantly enhance the E7 specific cellular immunity within the mice body（p〈0. 01）. After being immunized with E7^C91G-HSP70 fusion vaccine, tumor-bearing mice of the group being treated have significantly longer latency and survival periods, comparing with other three categories of E7 vaccines. Experiment shows that this vaccine has a significant effect on enhancing E7 positive tumor-treatment within mice body. After being immunized with E7^C91G-HSP70 vaccine, there were no pathological changes found in livers, kidneys and spleens of the mice, which proves that the vaccine is quite safe. After all, E7^C91G-HSP70 fusion vaccine has a much stronger tumor- treatment effect than thai of wild type E7 DNA vaccine.

Increased expression of 70 kD heat shock protein in cultured primary human keratinocytes induced by human papillomavirus 16 E6/E7 gene

Background Heat shock protein 70 （HSP70） is expressed highly in epithelial tumours associated closely with human papillomavirus 16 （HPV16） infections. However, evidence about the direct relationship between HSP70 expression and HPVs infections are still lacking. In the present study, we examined the expression of HSP70 in keratinocytes introduced with HPV16 E6/E7 oncogenes. Methods Stable transfected cells were established by transfection of the plasmids pLXSN16E6/E7 into cultured primary keratinocytes and subsequently selected by plasmid specific selection antibiotic （G418） at the required concentration. The expression of HSP70 in pLXSN16E6/E7 transfected keratinocytes was determined by Western blot. The correlation of HSP70 expression and E6/E7 transfeetion was further confirmed by doubly labelled immunofluorescent staining. Results Compared to non-transfected keratinocytes, there was a significant trend for higher levels of HSP70 in pLXSN16E6/E7 transfected keratinocytes. Doubly labelled immunofluorescent staining experiment showed that the co-localization of HPV16 E6/E7 and HSP70 in transfeeted keratinoeytes was observed and increased expression of HSP70 was strongly associated with the transfection of HPV16 E6/E7. Conclusions Our studies demonstrated increased levels of HSP70 proteins in keratinocytes stably transfected by HPV16 E6/E7 oncogenes. It suggests that the expression of HSP70 is modulated by HPV16 E6/E7 proteins, which may be involved in HPV16 E6/E7 induced immortalization.