Abstract LB-155: A new syngeneic MYCN-overexpressing neuroblastoma mouse model and MYCN-DNA vaccine

Abstract

Abstract High-level expression of MycN caused by amplification of the gene characterizes the malignant phenotype of neuroblastoma. Recent studies suggest that MYCN is a suitable target for immunotherapy, but up to now, a syngeneic NB mouse model over expressing MYCN is not available to examine immunotherapeutic strategies in vivo. Here, we report the development of a tetracycline inducible MYCN expressing murine NB cell line syngeneic to A/J mice and a MYCN-DNA vaccine. For this purpose, the murine NB cell line C1300, syngeneic to A/J mice, was stably transfected with a tetracycline inducible MYCN expression vector. Stable transfection was verified by real-time PCR and Western-Blot, revealing high expression levels of MYCN RNA and protein, respectively. Furthermore, a MYCN-DNA vaccine, based on epitopes encoding for three peptides from the murine MYCN protein sequence with high affinity to the A/J mouse MHC class I allele H2-Kk, was designed and tested in vivo for its ability to induce an antigen-specific immune response. Lymphocytes isolated from A/J mice vaccinated with the MYCN vaccine effectively lysed C1300-MYCN +tet cells in cytotoxicity assays in contrast to wild type C1300 cells and lymphocytes from control mice. Lymphocytes from minigene vaccinated mice produced significantly higher amounts of IFN-γ after stimulation with irradiated C1300 cells than lymphocytes from control mice. Interestingly, vaccine induced cytotoxic T lymphocytes also kill parental C1300 tumor cells which show low MYCN expression. We expect that this effect will be enhanced when MYCN-over expressing C1300 cells are employed in a similar cytotoxicity assay which will be reported at the meeting. In summary, we report the development of a new MYCN-DNA vaccine and a murine tetracycline inducible MYCN NB cell line providing an useful syngeneic mouse model for in vivo evaluation of MYCN directed immunotherapeutic strategies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-155. doi:10.1158/1538-7445.AM2011-LB-155