New strategy for efficient selection of dendritic cell-tumor hybrids and clonal heterogeneity of resulting hybrids

Abstract

ABBREVIATIONS ACKNOWLEDGEMENTSWe thank Pat Adcock for her secretarial assistance. This work was supported by NIH grants AI46755 (to H. Matsue), AR35068, AR43777 and AI43232 (to A. Takashima). Research PaperNew Strategy for Efficient Selection of Dendritic Cell-Tumor Hybrids and Clonal Heterogeneity of Resulting Hybrids ABSTRACTHeterotypic hybrids created between dendritic cells (DC) and tumor cells represent an efficient approach for loading DC with tumor-associated antigens (TAA) and DC-tumor hybrid vaccines have shown promising outcomes in various preclinical and clinical studies. Conventional DC-tumor hybrid preparations, however, are unavoidably contaminated by DC-tumor aggregates and DC loaded with tumor cell debris. Here we describe a new strategy for selecting genuine DC-tumor hybrids. A HAT-sensitive/zeocin-resistant DC clone (XS106-7 Zeo) was fused with a GFP-transduced fibrosarcoma clone (S1509a-GFP) by polyethylene glycol and heterotypic hybrid clones were established by limiting dilution in the presence of HAT and zeocin. CD45 (DC origin) and GFP (tumor origin) were both expressed in 91% (51/56 clones) of the resulting clones, indicating high efficiency of our strategy. Marked heterogeneity was observed among the hybrid clones and only one clone exhibited characteristic features of DC (CD86 and I-A expression, dendritic morphology, T cell-stimulatory capacity and IL-1β, IL-6 and TNFα production), suggesting that only small fractions of DC-tumor hybrids acquire and maintain the properties of parental DC. Finally, vaccination with this hybrid clone protected mice from subsequent growth of S1509a tumor cells, documenting the in vivo activity of DC-tumor hybrids in the complete absence of exogenous TAA.

Regulation of Tumor Immunity by Tumor/Dendritic Cell Fusions

“…Therefore, mature fusions have more active to stimulate CTL responses in the immunosuppressive environment in the growing tumor burden (Figure 4). Indeed, in murine models, tumor/DC fusions coadministrated with TLR9 (synthetic oligodeoxynucleotides (ODNs) containing specific bacterial unmethylated CpG motifs (CpG ODNs)) and TLR3 agonists (Poly(I:C)) significantly reduced melanoma metastasis through IL-12 production, compared with fusions alone [59, 82]. Moreover, tumor/DC fusions transduced with IL-12 [30, 87, 91, 96], IL-18 [90, 96], GM-CSF [47], IL-4 [88], CD40L [89] genes induced potentially increased therapeutic efficacy.…”

Antigen-Specific Polyclonal Cytotoxic T Lymphocytes Induced by Fusions of Dendritic Cells and Tumor Cells

“…Therefore, the fusions vaccine may represent an effective strategy for the treatment of human tumors. The DCs/tumor fusions vaccine not only provided protection against challenge with tumor cell, but also regressed the established tumors, including melanoma [11, 19, 24, 36–40], colorectal [12, 20, 34, 41–48], breast [49–53], esophageal [54], pancreatic [55], hepatocellular [56–60], lung [61, 62], laryngeal [63], renal cell carcinoma [64], sarcoma [65–67], myeloma [68–73], mastocytoma [74], and neuroblastoma [75]. …”

Cancer Vaccine by Fusions of Dendritic and Cancer Cells

“…Indeed, DCs/tumor fusion cell vaccines have been shown to possess the elements essential for processing and presenting tumor antigens to host immune cells for inducing effective antitumor immune response and for breaking T-cell tolerance to tumor-associated antigens in animal models [12, 20]. Many animal studies have demonstrated that the DCs/tumor fusion vaccine not only provided protection against challenge with tumor cells, but also regressed established tumors, including melanoma [21–27], colorectal [12–14, 18, 28–35], breast [36–39], esophageal [40], pancreatic [41], hepatocellular [42–46], lung [47, 48], laryngeal [49], renal cell carcinoma [50], sarcoma [51–53], myeloma [54–59], mastocytoma [60], and neuroblastoma [61]. …”