title: A DNA vaccine encoding a codon-optimized human papillomavirus type 16 E6 gene enhances CTL response and anti-tumor activity.
abstract: The HPV oncoproteins E6 and E7 are consistently expressed in HPV-associated cancer cells and are responsible for their malignant transformation. Therefore, HPV E6 and E7 are ideal target antigens for developing vaccines and immunotherapeutic strategies against HPV-associated neoplasms. Recently, it has been demonstrated that codon optimization of the HPV-16 E7 gene resulted in highly efficient translation of E7 and increased the immunogenicity of E7-specific DNA vaccines. Since vaccines targeting E6 also represent an important strategy for controlling HPV-associated lesions, we developed a codon-optimized HPV-16 E6 DNA vaccine (pNGVL4a-E6/opt) and characterized the E6-specific CD8+ T cell immune responses as well as the protective and therapeutic anti-tumor effects in vaccinated C57BL/6 mice. Our data indicated that transfection of human embryonic kidney cells (293 cells) with pNGVL4a-E6/opt resulted in highly efficient translation of E6. In addition, vaccination with pNGVL4a-E6/opt significantly enhanced E6-specific CD8+ T cell immune responses in C57BL/6 mice. Mice vaccinated with pNGVL4a-E6/opt are able to generate potent protective and therapeutic antitumor effects against challenge with E6-expressing tumor cell line, TC-1. Thus, DNA vaccines encoding a codon-optimized HPV-16 E6 may be a promising strategy for improving the potency of prophylactic and therapeutic HPV vaccines with potential clinical implications.
authors.affiliation: Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital and Chung Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Cheng-Tao
authors.initials: CT
authors.lastname: Lin
authors.forename: Ya-Chea
authors.initials: YC
authors.lastname: Tsai
authors.forename: Liangmei
authors.initials: L
authors.lastname: He
authors.forename: Roanne
authors.initials: R
authors.lastname: Calizo
authors.forename: Hung-Hsueh
authors.initials: HH
authors.lastname: Chou
authors.forename: Ting-Chang
authors.initials: TC
authors.lastname: Chang
authors.forename: Yung-Kuei
authors.initials: YK
authors.lastname: Soong
authors.forename: Chien-Fu
authors.initials: CF
authors.lastname: Hung
authors.forename: Chyong-Huey
authors.initials: CH
authors.lastname: Lai
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003062:Codon / Q000235:genetics; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009856:Oncogene Proteins, Viral / Q000235:genetics*; D030361:Papillomavirus Infections / Q000276:immunology / Q000517:prevention & control*; D012097:Repressor Proteins / Q000235:genetics*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014611:Vaccination; D019444:Vaccines, DNA / Q000235:genetics* / Q000276:immunology
chemical_list: D003062:Codon; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D019444:Vaccines, DNA