In vitro antitumor cytotoxic T lymphocyte response induced by dendritic cells transduced with ΔNp73α recombinant adenovirus

Delta Np73 alpha , the N-terminal truncated form of p73 alpha 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 Delta Np73 alpha (DNp73 alpha ) on breaking immune tolerance and induction of immunity against DNp73 alpha -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 DNp73 alpha cDNA (Ad-DNp73 alpha ) or a control vector Ad-EGFP, using the centrifugal force method. Induction of DNp73 alpha -specific CTL response was evaluated by a cytotoxic assay against the three human tumor cell lines with different DNp73 alpha expression levels. The viability and activation status of transduced dendritic cells were assessed by flow cytometry. The dendrocyte/Ad-DNp73 alpha -activated cytotoxic T lymphocytes showed significantly higher cytotoxicity against the cell lines A549/DNp73 alpha , K-562 that expressed DNp73 alpha than the DNp73 alpha -null MCF-7 cells. The DCs/Ad-DNp73 alpha 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-DNp73 alpha can induce specific and sustained T cell responses against tumors expressing this variant p53-related gene.