MUC1 expressing tumor growth was retarded after human mucin 1 (MUC1) plasmid DNA immunization.

Abstract

IntroductionNaked DNA is one of the attractive tools for vaccination studies. We studied naked DNA vaccination against the human tumor antigen, mucin, which is encoded by the MUC1 gene.MethodsWe constructed the pcDNA3.0-MUC1 (pcDNA-MUC1) plasmid expressing an underglycosylated MUC1 protein. BALB/c mice were immunized intradermally thrice at 2-weeks intervals with pcDNA-MUC1. Two weeks after the last immunization, tumor challenge experiments were performed using either the CT26 or TA3HA tumor cell lines, both of which transduce human MUC1.ResultsImmune cell population monitoring from pcDNA-MUC1-immunized animals indicated that immune cell activation was induced by MUC1-specific immunization. Using intracellular fluorescence activated cell sorting and enzyme-linked immunosorbent spot assay, we reported that interferon-γ secreting CD8+ T cells were mainly involved in MUC1-specific immunization. In all mice immunized with MUC1 DNA, tumor growth inhibition was observed, whereas control mice developed tumors (p < 0.001).ConclusionOur results suggest that intradermal immunization with MUC1 DNA induces MUC1-specific CD8+ T cell infiltration into tumors, elicits tumor-specific Th1-type immune response, and inhibits tumor growth.