ΔNp73α, the N-terminal truncated form of p73α is a candidate tumor antigen because of its selective expression in many human cancers and lack of expression in normal tissues. Therefore, we investigated the effects of dendritic cells infected with adenoviral ΔNp73α (DNp73α) on breaking immune tolerance and induction of immunity against DNp73α-expressing (A549 lung cancer, K-562 leukemia) and non-expressing (MCF-7 breast cancer) cell lines. Immature dendritic cells generated in the presence of interleukin-4 and granulocyte/macrophage colony-stimulating factor from a human umbilical cord blood were transduced with a recombinant adenoviral (Ad) vector encoding full-length human DNp73α cDNA (Ad-DNp73α) or a control vector Ad-EGFP, using the centrifugal force method. Induction of DNp73α-specific CTL response was evaluated by a cytotoxic assay against the three human tumor cell lines with different DNp73α expression levels. The viability and activation status of transduced dendritic cells were assessed by flow cytometry. The dendrocyte/Ad-DNp73α-activated cytotoxic T lymphocytes showed significantly higher cytotoxicity against the cell lines A549/DNp73α, K-562 that expressed DNp73α than the DNp73α-null MCF-7 cells. The DCs/Ad-DNp73α showed higher survival rates than the DCs/Ad-EGFP or untransduced DCs, presumably due to the inhibition of cell death. These findings, with potential applications for immunotherapy, demonstrate that dendrocytes transduced with Ad-DNp73α can induce specific and sustained T cell responses against tumors expressing this variant p53-related gene.

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