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Prevention of Liver Metastasis in Colon Cancer Bearing Mice By Adenovirus B7H3 Gene Therapy
Catalin Mario Lupu, University of Heidelberg, Faculty of Medicine, Heidelberg, Baden Würtenberg, Germany; Christoph Eisenbach, Internal Medicine IV, University of Heidelberg,, Heidelberg, baden Würtenberg, Germany; Ming Xiang, Otto Mayerhof Zentrum, heidelberg, Baden Würtenberg, Germany; Wolfgang Stremmel, Jens Encke, Internal Medicine IV, University of Heidelberg, Heidelberg, Baden Würtenberg, Germany
BACKGROUND: T cell activation is regulated by costimulatory molecules of the B7 superfamily. B7-H3 is the newest member of this family. In human and mouse it is widely expressed in various normal tissues. Whether in human was proved that B7-H3 costimulates the proliferation of CD4+ and CD8+ T cells, and enhances induction of IFN-ã expression, in mouse function of B7-H3 in tumour regression remain controversial. OBJECTIVE: The aim of the study is to investigate cellular immune responses against colon carcinomas and secondary liver metastasis in mice after intratumoral injection of a B7-H3 expressing recombinant adenovirus as a model of immune and gene therapy to prevent and cure liver metastasis in patients with colon carcinoma. METHODS: C26 - colon carcinoma cells were transfected with the pcDNA3.1-B7-H3 plasmid using the Calcium Phosphate method. PCR was applied to test efficiency of gene transfer. Under selective pressure with Neomycin positive clones were selected by limiting dilution and expanded. Transfected cells were analyzed for B7-H3 expression by FACS using specific anti B3-H3 antibody FITC. For intratumoral administration a replication defective, B7-H3 recombinant Adenovirus (Ad5-B7-H3) was established. For in vivo experiments we have used BALB/c mouse orthotopic model of colon cancer. RESULT: The gene B7H3 was successfully transfected into the C26 cell line and the stable clone was selected and named C26B7H3. Colon carcinoma cells transfected with recombinant plasmids pcDNA3.1-B7-H3 grew vigorously in vitro and express high level of B7-H3 confirmed by Western Blotting and FACS analysis. After orthotopicaly injection of C26B7H3 tumours didn't growth or growth lowlier than after C26 injection. This preliminary result suggest that B7H3 could have an anti tumour effect in mouse. ONCLUSION: The B7-H3 gene can be transfected into colon carcinoma cells and can be expressed steadily in vitro, with a view to increase the immunongenity of C26 cells. We have successfully generated appliance to study in vivo immune response against colon cancer, further more a recombinant adenovirus (Ad5-B7-H3) to prevent liver metastasis
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