Abstract
Mammaglobin A (MGBA) is a novel breast cancer-associated antigen almost exclusively over-expressed in primary and metastatic human breast cancers, making it a potential therapeutic target for breast cancer. The development of dendritic cell (DC)-induced tumor antigen specific CD8(+) cytotoxic T lymphocytes (CTLs) may hold promise in cancer immunotherapy. In this study we constructed recombinant replication-defective adenoviral (Ad) vectors encoding MGBA and evaluated their ability to trigger anti-tumor immunity in vitro. DCs were isolated from the human peripheral blood monocyte cells (PBMCs) of two HLA-A33(+) healthy female volunteers, and infected with adenovirus carrying MGBA cDNA (Ad-MGBA). After that, the Ad-MGBA-infected DCs were used to stimulate CD8(+) CTLs in vitro and the latter was used for co-culture with breast cancer cell lines. The data revealed that infection with Ad-MGBA improved DC maturation and up-regulated the expression of co-stimulatory molecules and the secretion of interleukin-12 (IL-12), but down-regulated interleukin-10 (IL-10) secretion from DCs. Ad-MGBA-infected DC-stimulated CD8(+)CTLs displayed the highest cytotoxicity towards HLA-A33(+)/MGBA(+) breast cancer MDA-MB-415 cells compared with other CD8(+)CTL populations, and compared with the cytotoxicity towards HLA-A33(-)/MGBA(+) breast cancer HBL-100 cells and HLA-A33(-)/MGBA(-) breast cancer MDA-MB 231 cells. In addition, Ad-MGBA-infected DC-stimulated CD8(+) CTLs showed a high level of IFNγ secretion when stimulated with HLA-A33(+)/MGBA(+) breast cancer MDA-MB-415 cells, but not when stimulated with HLA-A33(-)/MGBA(+) HBL-100 and HLA-A33(-)/MGBA(-)MDA-MB-231 cells. In addition, killing of CD8(+)CTLs against breast cancer was in a major histocompability complex (MHC)-limited pattern. Finally, the data also determined the importance of TNF-α in activating DCs and T cells. These data together suggest that MGBA recombinant adenovirus-infected DCs could induce specific anti-tumor immunity against MGBA(+) breast cancers, which could provide a novel strategy in the immunotherapy of breast cancer.