The mannosylated extracellular domain of Her2/neu produced in P. pastoris induces protective antitumor immunity.
BACKGROUND
Her2/neu is overexpressed in various human cancers of epithelial origin and is associated with increased metastatic potential and poor prognosis. Several attempts have been made using the extracellular domain of Her2/neu (ECD/Her2) as a prophylactic vaccine in mice with no success in tumor prevention.


METHODS
The extracellular domain of Her2/neu (ECD/Her2) was expressed in yeast P. pastoris, in a soluble highly mannosylated form. The immune response of the immunization with this recombinant ECD/Her2 was analyzed using immunoprecipitation and western blot analysis, proliferation and cytotoxicity assays as well as specific tumor growth assays.


RESULTS
Mannosylated ECD/Her2 elicited a humoral response with HER2/neu specific antibodies in vaccinated mice, which were able to reduce the proliferation rate of cancer cells in vitro. Moreover, it elicited a cellular response with Her2/neu-specific CTL capable of lysing tumor cells, in vitro. When immunized Balb/c and HHD mice were challenged with Her2/neu-overexpressing cells, tumor growth was inhibited.


CONCLUSIONS
Here we report on the efficacy of the extracellular domain of human Her2/neu produced in yeast P. pastoris, which confers mannosylation of the protein, to act as a potent anti-tumor vaccine against Her2/neu overexpressing tumors. Specific cellular and humoral responses were observed as well as efficacy.
Dimitriadis
Alexios
A
Laboratory of Molecular Biology and Immunobiotechnology, Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece. aldimitriadis@pasteur.gr
Gontinou
Chrysanthi
C
Baxevanis
Constantin N
CN
Mamalaki
Avgi
A
D043925:Angiogenesis Inducing Agents / Q000097:blood; D000818:Animals; D019496:Cancer Vaccines / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D015870:Gene Expression; D006801:Humans; D007109:Immunity; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000276:immunology* / Q000517:prevention & control*; D010843:Pichia / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D043925:Angiogenesis Inducing Agents; D019496:Cancer Vaccines; D018719:Erb-b2 Receptor Tyrosine Kinases; D011994:Recombinant Proteins; C508053:ERBB2 protein, human