title: Cross-Presentation of the Oncofetal Tumor Antigen 5T4 from Irradiated Prostate Cancer Cells--A Key Role for Heat-Shock Protein 70 and Receptor CD91.
abstract: Immune responses contribute to the success of radiotherapy of solid tumors; however, the mechanism of triggering CD8(+) T-cell responses is poorly understood. Antigen cross-presentation from tumor cells by dendritic cells (DC) is a likely dominant mechanism to achieve CD8(+) T-cell stimulation. We established a cross-presentation model in which DCs present a naturally expressed oncofetal tumor antigen (5T4) from irradiated DU145 prostate cancer cells to 5T4-specific T cells. The aim was to establish which immunogenic signals are important in radiation-induced cross-presentation. Radiation (12 Gy) caused G2-M cell-cycle arrest and cell death, increased cellular 5T4 levels, high-mobility protein group-B1 (HMGB1) release, and surface calreticulin and heat-shock protein-70 (Hsp70) expression in DU145 cells. DCs phagocytosed irradiated tumor cells efficiently, followed by upregulation of CD86 on phagocytic DCs. CD8(+) 5T4-specific T cells, stimulated with these DCs, proliferated and produced IFNγ. Inhibition of HMGB1 or the TRIF/MyD88 pathway only had a partial effect on T-cell stimulation. Unlike previous investigators, we found no evidence that DCs carrying Asp299Gly Toll-like receptor-4 (TLR4) single-nucleotide polymorphism had impaired ability to cross-present tumor antigen. However, pretreatment of tumor cells with Hsp70 inhibitors resulted in a highly statistically significant and robust prevention of antigen cross-presentation and CD86 upregulation on DCs cocultured with irradiated tumor cells. Blocking the Hsp70 receptor CD91 also abolished cross-presentation. Together, the results from our study demonstrate that irradiation induces immunologically relevant changes in tumor cells, which can trigger CD8(+) T-cell responses via a predominantly Hsp70-dependent antigen cross-presentation process.
authors: Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors: Josephine
authors: J
authors: Salimu
authors: Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors: Lisa K
authors: LK
authors: Spary
authors: Velindre Cancer Centre, Velindre NHS Trust, Cardiff, United Kingdom.
authors: Saly
authors: S
authors: Al-Taei
authors: Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors: Aled
authors: A
authors: Clayton
authors: Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors: Malcolm D
authors: MD
authors: Mason
authors: Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom.
authors: John
authors: J
authors: Staffurth
authors: Institute of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom. tabiz@cardiff.ac.uk.
authors: Zsuzsanna
authors: Z
authors: Tabi
mesh_terms: D017951:Antigen Presentation / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D059447:Cell Cycle Checkpoints / Q000528:radiation effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D045142:Cross-Priming / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D056747:Immunomodulation / Q000528:radiation effects; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology*; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D011110:Polymorphism, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D021381:Protein Transport; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D024243:HMGB1 Protein; D018840:HSP70 Heat-Shock Proteins; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D008562:Membrane Glycoproteins; D053594:Myeloid Differentiation Factor 88; D051197:Toll-Like Receptor 4; C063709:trophoblastic glycoprotein 5T4, human