Antibody-Dependent Natural Killer Cell–Mediated Cytotoxicity Engendered by a Kinase-Inactive Human HER2 Adenovirus-Based Vaccination Mediates Resistance to Breast Tumors

Abstract

Cancer vaccines may have applications in the therapy and prevention of mammary carcinoma. To investigate such applications, we constructed a recombinant adenoviral vaccine expressing a kinase-inactive mutant form of human HER2 and introduced this into BALB/c wild-type (WT) or HER2 transgenic mice. Here, we report contributions by antibody responses and natural killer (NK) cells in tumor protection in this model. One i.p. vaccination protected WT mice from the HER2-expressing mouse carcinoma D2F2/E2. Half of the HER2 transgenic mice were protected fully and long term after preventive vaccination. Tumor growth in mice that eventually developed neoplastic lesions was delayed. Protection in WT and HER2 transgenic mice was associated with high or low levels of IgG2a antibodies, respectively, whereas CTLs were observed in WT but not in HER2 transgenic mice. Depleting CD4 + or CD8 + cells in vaccinated WT mice had limited effects, suggesting that protection was largely independent of CD4 + or CD8 + T cells. In contrast, antibody-mediated tumor rejection seemed to contribute significantly based on a loss of protection in mice deficient for Fc-γ RI/III or B cells. Further, a role for antibody-dependent cellular cytotoxicity (ADCC) mediated by NK cells was indicated by evidence that vaccine protection could be abolished by in vivo depletion of NK cells. Lastly, NK cells and immune sera purified from WT or HER2 transgenic mice exhibited efficient ADCC of HER2-expressing tumor cells in vitro. Our findings define a critical requirement for NK cells in vaccine-induced protection against HER2-expressing tumors.

Breast cancer vaccines delivered by dendritic cell-targeted lentivectors induce potent antitumor immune responses and protect mice from mammary tumor growth

“…Mice immunized with LV-ERBB2 generated a marked amount of ErbB2-specific CD8+ T cells as compared with mice immunized with a LV-GFP control LV (1.68% vs. 0.25%, p< 0.001, t test). This compares favorably to previously published DNA, vector and DC vaccines, which have yielded 3–7-fold increases in tumor-specific CD8+ T cells with more complicated immunization regimens [28,30–32]. …”

“…The entire mouse Lalba coding sequence was inserted into the LV. In the case of ErbB2, only the extracellular domain of ErbB2 was inserted into the vector, as the dominant epitopes previously identified in mice and humans fall within this region [28,29]. LV particles were produced by transfection into 293T cells according to standard protocols, followed by ultracentrifugation.…”

“…We performed a single immunization of Balb/cJ mice with 1 × 10 7 TU of LV-ERBB2 and harvested splenocytes two weeks after immunization. By coculturing bulk splenocytes with a peptide of a known ErbB2 H-2 K d epitope [28], we were able to identify the percentage of CD8+ T cells that were specific for ErbB2 (Fig. 2A and 2B).…”

“…Splenocytes (1 × 10 6 ) were cultured with an ErbB2 peptide TYLPTNASL [28] (Genscript) at 10 µg/mL, for 6 hours in the following solution: RPMI media, 10% FBS, 10 U/mL penicillin, 100 ug/mL streptomycin, 2 mM L-glutamine, 0.67 uL/mL GolgiPlug™ (BD Biosciences #555029). Cells were washed and stained with antibodies to mouse CD4 and CD8 (Biolegend #130312, #100706).…”

Cripto-1 Plasmid DNA Vaccination Targets Metastasis and Cancer Stem Cells in Murine Mammary Carcinoma

“…Cripto-1 specific humoral response DNA vaccination in BALB/c mice can elicit a humoral response (24). We therefore evaluated the humoral response after vaccination with pmCR-1 (25,26).…”