Decitabine and Interferon-γ enhance neuroblastoma cells susceptibility to CTL-mediated killing (156.26)

Abstract

Abstract MAGE-A1, MAGE-A3, and NY-ESO-1 are cancer-testis (CT) antigens expressed on a number of malignant solid tumors, including neuroblastoma, but many tumor cell lines down-regulate the expression of CT antigens as well as major histocompatibility (MHC) antigens, precluding recognition by antigen specific T cells. If expression of cancer antigens as well as MHC molecules could be enhanced pharmacologically, the efficacy of CT antigen specific immunotherapy could be improved. We have demonstrated that the expression of MAGE-A1, MAGE-A3, and NY-ESO-1 can be upregulated on neuroblastoma cells following exposure to the demethylating agent 5-aza-2’-deoxycytidine (decitabine, DAC) in 10/10 neuroblastoma cell lines. Culture of neuroblastoma cell lines with IFN-γ was associated with an increased expression of either MHC Class I or II by cytofluorometry, with MHC Class I upregulated in 10/10 of these cell lines, although to varying degrees. MAGE-A1, MAGE-A3, and NY-ESO-1 specific CTL were cultured from volunteer donors by stimulating peripheral blood mononuclear cells with dendritic cells pulsed with overlapping peptide mixes derived from full length proteins, and these CTL lysed HLA partially matched, DAC treated neuroblastoma and glioblastoma cell lines. These studies confirm that DAC and IFN-γ can be used to increase the expression of CT antigens and MHC molecules on neuroblastoma cells, and pre-treatment with these agents makes tumor cell lines more susceptible to CTL mediated killing.