title: Naked DNA immunization as an approach to target the generic tumor antigen survivin induces humoral and cellular immune responses in mice.
abstract: Survivin, a 16.5 kDa tumor associated antigen, is the smallest member of the inhibitor of apoptosis family that is abundantly expressed during development but essentially absent in normal adult tissues. Interestingly, survivin expression is up-regulated in virtually all types of cancers studied, as well as in vascular endothelial cells during tumor associated angiogenesis. Survivin links apoptosis to cell cycle progression and plays a pivotal role in regulation of cell proliferation. These characteristics make survivin a potentially promising generic target for cancer immunotherapy. Hence, a genetic immunization strategy to induce tumor-specific immune responses against human survivin in a pre-clinical animal model was developed. In initial studies, BALB/c mice were immunized by intramuscular injection with DNA coding for human survivin (pcDNA3.1/hSurv). In addition, a construct encoding a secreted version of survivin (pSecTag2B/hSurv) was designed. A plasmid coding for murine granulocyte-macrophage colony-stimulating factor (GM-CSF) was co-injected in both cases as a molecular adjuvant. Expression of survivin following transfection in mouse cells was corroborated. Humoral responses against human survivin were detected in mice sera using two immunization protocols (injections at 2- or 3-week intervals). The humoral response was markedly improved by secretion of survivin and co-expression of GM-CSF. The predominant antibody subclass detected in responsive mice was IgG2a, suggesting that a Th1-CD4+ cellular response had been induced. Furthermore, DNA immunization with survivin encoding vectors generated an effective CD8+ T cell response measured as an increase of cytotoxic Interferon-gamma (IFN-gamma) secreting CD8+ T cells. In conclusion, intramuscular genetic immunization of mice with human survivin encoding plasmids induced a survivin-specific humoral as well as cellular immune response in recipient mice. Secretion of survivin and co-injection of GM-CSF as a genetic adjuvant appear to be more important in generating an humoral than a cellular immune response.
authors.affiliation: FONDAP Center for Molecular Studies of the Cell (CEMC), University of Chile, Av. Independencia 1027, Independencia, Santiago, Chile.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Lladser
authors.forename: Mario
authors.initials: M
authors.lastname: Párraga
authors.forename: Licarallén
authors.initials: L
authors.lastname: Quevedo
authors.forename: Maria
authors.initials: M
authors.lastname: Carmen Molina
authors.forename: Soledad
authors.initials: S
authors.lastname: Silva
authors.forename: Arturo
authors.initials: A
authors.lastname: Ferreira
authors.forename: Rosario
authors.initials: R
authors.lastname: Billetta
authors.forename: Andrew F
authors.initials: AF
authors.lastname: G Quest
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000096:biosynthesis*; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D019496:Cancer Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D045744:Cell Line, Tumor; D005260:Female; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007111:Immunity, Cellular; D051034:Inhibitor of Apoptosis Proteins; D007371:Interferon-gamma / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012097:Repressor Proteins; D000077022:Survivin; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; C107489:BIRC5 protein, human; C117749:Birc5 protein, mouse; D019496:Cancer Vaccines; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D012097:Repressor Proteins; D000077022:Survivin; D019444:Vaccines, DNA; D007371:Interferon-gamma