Dendritic cells transduced with TAT protein transduction domain-containing tyrosinase-related protein 2 vaccinate against murine melanoma

Incorporation of an 11 amino acid region of the HIV TAT protein transduction domain (TAT PTD) into proteins facilitates rapid, efficient entry into cells. We previously showed that rTAT-PTD-OVA-transduced dendritic cells (DC) stimulated antigen (Ag)-specific CTL and Th cells, and vaccinated against OVA-expressing tumors. Here we studied B16 melanoma in C57BL/6 mice, using murine tyrosinase-related protein 2 (Trp2) as a candidate tumor Ag. We produced a 472-amino acid N-terminal fragment of Trp2 protein (rTrp2Δ) with or without PTD. Although PTD-deficient rTrp2Δ was ineffective, mice given rTAT-PTD-Trp2Δ-transduced DC were efficiently primed for Trp2_180-188 peptide-specific and B16-reactive CTL. In 58% of such mice, growth of melanomas was prevented. Trp2₁₈₀-₁₈₈ peptide-pulsed DC protected 35% of recipients, and irradiated GM-CSF-producing B16 cells protected 75%. rTAT-PTD-Trp2Δ-transduced DC induced a more vigorous memory response to B16 rechallenge than the other regimens, and protected 30% of recipients from progressive tumor development in treatment studies. In this setting, Trp2 peptide-treated DC protected 20% and irradiated GM-CSF-producing cells protected 0%. Both tumor prevention and tumor treatment were CD8⁺ T cell dependent. Vaccination with rTAT-PTD-Trp2Δ-transduced DC induced a robust CTL response and durable anti-melanoma immunity. This approach should be clinically applicable, and offers theoretical and practical advantages to those that are in current use.