Research article

The mannosylated extracellular domain of Her2/neu produced in P. pastoris induces protective antitumor immunity

Alexios Dimitriadis¹ , Chrysanthi Gontinou¹ , Constantin N Baxevanis² and Avgi Mamalaki¹

¹Laboratory of Molecular Biology and Immunobiotechnology, Department of Biochemistry, Hellenic Pasteur Institute, 127 Vas. Sofias Ave., 11521 Athens, Greece

²Cancer Immunology and Immunotherapy Center, Saint Savas Cancer Hospital, 171 Alexandras Ave., 11522 Athens, Greece

author email corresponding author email

BMC Cancer 2009, 9:386doi:10.1186/1471-2407-9-386

Published:	30 October 2009

Abstract

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.

Conclusion

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.