pastoriselicits a humoral response against Her2/neu == To determine whether the recombinant mannosylated ECD/Her2 expressed in yeastP. cellular and humoral responses were observed as well as efficacy. == Background == The Her2/neu (ErbB2) gene encodes a 185 kDa transmembrane glycoprotein that belongs to the family of epidermal growth factor receptors. It consists of a 620 aa extracellular domain name, followed by a 23 aa transmembrane domain name and a 490 aa intracellular domain name with a tyrosine kinase activity [1]. It is a ligand-less receptor and it is the preferred heterodimerization partner for ligand-bound EGFR, Her3 and Her4, providing as a co-receptor. Any alteration of the strongly regulated EGF receptor signaling pathways prospects to cellular abnormalities and tumorigenesis [2]. The Her2/neu gene has a low expression in normal tissues. However, it is amplified and overexpressed in ~30% of invasive breast carcinomas and it is associated with increased metastatic potential and poor prognosis. Overexpression of the Her2/neu receptor is also observed in various other human cancers, including lung, ovary, kidney, and bladder [3]. Several reports have shown that this Her2/neu molecule is usually immunogenic, since it may generate antibodies and peptide-specific CTL response in some patients [4]. Therefore Her2/neu is an attractive target for active immunotherapy. DNA- and peptide-based vaccines were able to break tolerance and generate tumor antigen-specific immunity in animal models [5-8]. However, when the extracellular domain name of the Her2/neu protein, produced in cell lines which confer normal mammalian glycosylation, was used as a vaccine, it could not confer protection against Her2/neu overexpressing tumors [9-11]. An Tipranavir effective immune response was elicited only when ECD/Her2 was fused to cytokines [12] or combined with antibodies Tipranavir fused to cytokines [11]. Given that antigen presenting cells (APCs) do recognize and direct mannosylated antigens for degradation [13], it was recently shown that the use of fungal systems to mannosylate vaccine candidates can enhance immunogenicity in the context of CD4+[14] and CD8+T cells [15]. The present study utilizes the mannosylated extracellular domain name of the human HER2/neureceptor (ECD/Her2) produced in yeastP. pastoristo reduce tumor growth. ECD/Her2 elicited a humoral response in vaccinated mice with specific antibodies against Her2/neu that were able to reduce the proliferation rate of malignancy cellsin vitro. It, also, elicited a cellular response with Her2/neu-specific CTL capable of lysing tumor cellsin vitro. When Balb/c and HHD vaccinated mice were challenged with Her2/neu overexpressing cells, tumor growth was inhibited. These results suggest that ECD/Her2 is a good candidate for any tumor antigen vaccine as it prolongs tumor free survival and overall survival of vaccinated mice. == Methods == == Animals == Female BALB/c obtained from Harlan Laboratories (Indianapolis, IN, USA) and HHD mice (2 m-/-, H-2Db-/-and expressing a HLA.A2.1 monochain composed of a chimeric heavy chain, 1 and 2 domains of HLA-A*0201 and the 3 intracellular domain name of Db[16]) obtained from Institut Pasteur (Paris, France), were used. All mice were managed in pathogen-free conditions in the animal facilities of the Hellenic Pasteur Institute. Experiments were performed according to the Greek and European regulations on Animal Welfare and with General public Health Service recommendations. == Cell lines == D2F2/E2, a mouse mammary tumor cell collection stably transfected with the human Her2/neu molecule, was previously described [17]. This cell collection, as well as the parental D2F2 cell collection, was managed in hi-glucose DMEM, supplemented with 100 models/mL Penicillin, 100 g/mL Streptomycin, 10% FBS, 10% NCTC 109, 1% non-essential amino acids and 5% Sodium Bicarbonate. ALC.A2.1.hHer2, a murine lymphoma cell collection stably transfected with the HLA.A2.1 and the human Mouse monoclonal to Glucose-6-phosphate isomerase Her2/neu molecule [8] and the SK-BR-3 cell collection were maintained in RPMI 1640, supplemented with 100 models/mL Penicillin, 100 g/mL Streptomycin and 10% FBS. All cell lines were managed at 37C under a 5% Tipranavir CO2- 95% air flow atmosphere. == Soluble expression of ECD/Her2 in yeast Pichia pastoris == The extracellular domain name of human Her2/neu receptor (ECD/Her2, aminoacid residues 1 – 627) was previously enzymatically amplified by PCR and subcloned into the expression vector pPICZaC (Invitrogen, Carlsbad, California, USA) for soluble expression in yeastP. pastoris[18]. Protein production was induced with methanol while cells were produced at 30C for 72 h. The culture supernatant was exceeded through a 0.22 – m membrane filter, concentrated using the Minitan Ultrafiltration System (Millipore, Billerica, Massachusetts, USA) equipped with 30 kDa cut-off membrane and then dialyzed extensively against 20 mM sodium phosphate buffer pH 7.4, containing 0.5 M NaCl.