[Dendritic cells infected by recombinant adeno-associated virus with CEA gene to induce antigen-specific CTL response to CD44(+)CD24(-/low) cells from MCF-7 breast cancer cell line]

Abstract

Objective: To infect dendritic cells (DC) by recombinant human adeno-associated virus (rh-AAV) vector with CEA gene to generate antigen-specific CTL cells in vitro and to assay the CEA specific cytotoxic T lymphocyte(CTL), response to CD44(+)CD24(-/low) breast cancer stem cells.

Methods: Peripheral blood mononuclear cells were induced to generate DCs by cytokines interleukin-4(IL-4), granulocyte-macrophage colony-stimulating factor(GM-CSF)and tumor necrosis factor-alpha(TNF-α) while T lymphocytes were cultured with cytokines interleukin-2(IL-2). DCs were infected by CEA gene containing rh-AAV. After being matured, DCs were co-cultured with T cells to generate CTL cells. CD44(+)CD24(-/low) breast cancer stem cells were sorted out from MCF-7 and MDA-MB-231 cells. CEA specific CTL response to CD44(+)CD24(-/low) breast cancer stem cells was assayed by MTT method.

Results: The percentages of CD44(+)CD24(-/low) breast cancer stem cells subsets in MCF-7 and MDA-MB-231 were 5.1% and 76.3% respectively. DCs transfected with CEA gene could induce CEA antigen CTLs response. The killing ratio of MCF-7 cells in CEA gene transfection group was 46.5% plusmn; 15.0% with significant difference (P=0.009) as compared with that of CEA gene untransfection group. As for CD44(+)CD24(-/low) breast cancer stem cells subset from MCF-7 cells, CEA gene transfection group resulted in a higher killing ratio of 44.7% ± 28.2% as compared with that of CEA untransfection group. While the inhibitory rate of non-breast cancer stem cells subset from MCF-7 cells in CEA gene transfection group was 50.6% ± 22.2% (P=0.05). CTL cells generated by DCs transfected with CEA gene did not show inhibitory activity to MDA-MB-231 breast cancer cells (without CEA expression) as compared with CEA gene untransfection group. It was the same in CD44(+)CD24(-/low) breast cancer stem cells subset and non-breast cancer stem cells subset from MDA-MB-231 breast cancer cells (P>0.05).

Conclusion: DCs infected by rh-AAV with CEA gene could induce antigen-specific CTL response to kill CEA expressing breast cancer cells involved in CD44(+)CD24(-/low) breast cancer stem cells subset. It suggests that immune therapy might be a potential treatment of breast cancer stem cells.