RESUMO
BACKGROUND: The ultimate success of cancer vaccination is primarily dependent upon the generation of tumour-specific CTLs. Protein-based vaccination, while safe, poorly elicits such CTL responses. As fusion of an antigen to the HIV-1 Tat transduction domain was reported to increase MHC class I presentation and CTL responses in vitro, we tested the potency of this approach to augment tumour-directed responses. MATERIALS AND METHODS: Human papillomavirus type 16 (HPV16) E7 proteins, fused (E7-Tat) or not (E7) to Tat carboxy-terminal region, were produced and studied in vitro and in vivo. RESULTS: E7-Tat, not E7, penetrated the cell membrane and was transcriptionally active. In vitro, E7-Tat induced higher IFN-gamma production from E7-specific T-cells than E7. In C57BL/6 mice, E7-Tat mixed with Quil A generated enhanced prophylactic and therapeutic suppression of HPV16-positive C3 tumour outgrowth. Similar, but greatly enhanced E7-specific effector and helper T-cell responses were elicited following E7-Tat/Quil A rather than E7/Quil A vaccination. CONCLUSION: This study offers a new strategy for improving subunit cancer vaccines.
Assuntos
Vacinas Anticâncer/imunologia , Produtos do Gene tat/imunologia , Imunoterapia/métodos , Neoplasias Experimentais/terapia , Proteínas Oncogênicas Virais/imunologia , Proteínas Recombinantes de Fusão/imunologia , Células 3T3 , Adjuvantes Imunológicos/farmacologia , Animais , Vacinas Anticâncer/genética , Produtos do Gene tat/genética , Interferon gama/biossíntese , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias Experimentais/imunologia , Proteínas Oncogênicas Virais/genética , Proteínas E7 de Papillomavirus , Saponinas de Quilaia , Proteínas Recombinantes de Fusão/genética , Saponinas/farmacologia , Linfócitos T/imunologia , Linfócitos T/metabolismo , Linfócitos T Auxiliares-Indutores/imunologia , Células Tumorais CultivadasRESUMO
BACKGROUND: Genetic immunisation induces the endogenous production of the encoded antigens, which favours their presentation by MHC class I molecules. The E7 protein from "high risk" Human Papillomavirus (HPV) is constitutively expressed in cervical cancer and represents a target for immunotherapy. MATERIALS AND METHODS: Several E7-encoding DNA vaccines were constructed including unmodified E7 and E7 fused to ubiquitin or to the Invariant chain in order to increase the presentation of E7-derived peptides by MHC class I or II molecules, respectively. These vaccines were administered i.m. to C57BL/6 mice that were subsequently challenged with E7-positive tumour cell lines expressing different levels of MHC class I molecules. RESULTS: The E7-Ii fusion sequence protected a number of animals from tumour challenging. No differences were associated with the MHC class I status of the challenging cell lines. CONCLUSION: Engineering the intracellular pathway for antigen presentation is able to produce a valid therapeutic response even against tumours with down-regulated MHC class I.
