Complementary Antitumor Immunity Induced by Plasmid DNA Encoding Secreted and Cytoplasmic Human ErbB-2

Abstract

A plasmid DNA was constructed to encode the N-terminal 505 aa of human ErbB-2 (E2, HER-2/neu) and designated as secreted ErbB-2 (secE2). Recombinant secE2 protein was detected in the transfected cells and was secreted as an 80-kDa glycoprotein. Vaccination of BALB/c mice with secE2 DNA induced both IgG1 and IgG2a ErbB-2-specific Abs and protected ∼90% of mice against mouse mammary tumor D2F2, which expressed human ErbB-2 (D2F2/E2). The efficacy of secE2 vaccine was comparable with that of wild-type ErbB-2 DNA, which encodes the entire 1258 aa of ErbB-2 protein, induced only IgG2a E2-specific Abs, and stimulated greater CTL activity. Immune lymphocytes were stimulated in vitro with irradiated 3T3 cells, which expressed ErbB-2, Kd, and B7.1. CTL activity was measured by the lysis of E2-positive target cells and by intracellular IFN-γ production. To enhance CTL activation, mice were immunized with a combination of secE2 and cytoplasmic E2 (cytE2); the latter encodes the 1258-aa ErbB-2 protein that was released into the cytoplasm upon synthesis. Significant increase in CTL activity was demonstrated after mice were immunized with the combined vaccines and all mice were protected from D2F2/E2 tumor growth. Therefore, secE2, which induced Th2 Ab and weak CTL, conferred similar protection as E2, which induced Th1 Ab and strong CTL. Combined vaccination with secE2 and cytE2 resulted in Th2 Ab, strong CTL, and the most effective protection against tumor growth. The strategy of coimmunization with DNA that direct Ags to different subcellular compartments may be adapted as appropriate to optimize immune outcome.

N-terminally fusion of Her2/neu to HSP70 decreases efficiency of Her2/neu DNA vaccine

“…It neither caused CTL activity nor increased CD8 + /decreased Tregs percentage at the tumor site. Apparently, it acted via effective antibody-mediated mechanisms (Curcio et al 2003;Piechocki et al 2001;Rovero et al 2000). In contrast, pHSP70/Her2 administration led to higher IFN-γ and IL-4 level.…”

“…It has been demonstrated that rejection of tumor is mainly based on antibodies, cytotoxic T lymphocyte (CTL) response, and decrease in CD4 + CD25 + regulatory T cells (Curcio et al 2003;Lin et al 2004;Quaglino et al 2005). However, the role of Th2 antibodies, even in the absence of CTL activity, has been shown to be a major one (Piechocki et al 2001). Therefore, determining the effective response could be a promiscuous and yet devastating battle.…”

HER-2/neu-gene engineered dendritic cell vaccine stimulates stronger HER-2/neu-specific immune responses compared to DNA vaccination

“…11,35 More recently, it has also been reported that the antitumor immunity derived from vaccination of DNA encoding ICD of HER-2/neu was mediated by HER-2/neu-specific CTL, but not humoral response. 36,37 Conceptually, vaccination with DNA en- Previous reports have shown that AdV transfection itself can mature DCs. 38,39 In this study, our data also showed that the transfected DC neu upregulated the expression of immunologically important molecules (MHC class II, CD40, CD54 and CD86) and inflammatory cytokines (IL-6, TNF-a, IL-1b, macrophage inflammatory protein-beta (MIP-b) and IP-10), compared with the untransfected DCs, indicating that AdV-transfected DCs are more immunogenic form of DCs with high immunostimulatory properties and capability in stimulating both natural killer cells and CTL.…”

Anti-HER2 vaccines: new prospects for breast cancer therapy

“…Wei et al [46,47] have developed several DNA vaccines that encode a modified human HER2 protein without tyrosine kinase activity. The three main constructs were (1) pE2A that encodes a full-length HER2 in which Lys753 has been substituted by Ala to remove the ATP-binding Lys residue, (2) pE2TM that encodes the HER2 signal peptide, extracellular and transmembrane domains but not the intracellular one and (3) psecE2 that encodes the N-terminal portion (aa 1-505) of ECD as a secreted protein.…”