Murine tyrosinase expressed by a T7 vector in bone marrow-derived dendritic progenitors effectively prevents and eradicates melanoma tumors in mice

Dendritic cell (DC)-mediated cancer immunotherapy is a Very promising alter native approach to cancer treatment. In a previous study, we successfully t ransfected bone marrow-derived dendritic progenitors (BMDDPs) with a T7 vec tor - a nonviral, cytoplasmic-based autogene expression system - encoding a model tumor antigen, firefly luciferase, and subsequently stimulated the t ransfected eel Is to differentiate into DCs. When injected into experimenta l mice, those DCs generated a strong immune response against tumor cells be aring luciferase, which not only prevented occurrence of metastasis but als o eradicated existing tumors. In the present study, we constructed a T7 Vec tor encoding mouse tyrosinase, a well-known melanoma associated tumor antig en, and used it to transfect BM DDPs. Reverse transcriptase polymerase chai n reaction and Western analysis confirmed the expression of tyrosinase by D Cs differentiated from transfected BMDDPs. Two immunizations of these DCs a t a dose of 2x10(6) of each successfully prevented tumor growth. More impor tantly, one injection of 2x10(6) of these DCs into mice followed by five do ses of recombinant human interleukin-2 administration effectively eradicate d existing tumors as indicated by pulmonary metastasis assay.