title: Immune selection of hot-spot beta 2-microglobulin gene mutations, HLA-A2 allospecificity loss, and antigen-processing machinery component down-regulation in melanoma cells derived from recurrent metastases following immunotherapy.
abstract: Scanty information is available about the mechanisms underlying HLA class I Ag abnormalities in malignant cells exposed to strong T cell-mediated selective pressure. In this study, we have characterized the molecular defects underlying HLA class I Ag loss in five melanoma cell lines derived from recurrent metastases following initial clinical responses to T cell-based immunotherapy. Point mutations in the translation initiation codon (ATG-->ATA) and in codon 31 (TCA-->TGA) of the beta(2)-microglobulin (beta(2)m) gene were identified in the melanoma cell lines 1074MEL and 1174MEL, respectively. A hot-spot CT dinucleotide deletion within codon 13-15 was found in the melanoma cell lines 1106MEL, 1180MEL, and 1259MEL. Reconstitution of beta(2)m expression restored HLA class I Ag expression in the five melanoma cell lines; however, the HLA-A and HLA-B,-C gene products were differentially expressed by 1074MEL, 1106MEL, and 1259MEL cells. In addition, in 1259MEL cells, the Ag-processing machinery components calnexin, calreticulin, and low m.w. polypeptide 10 are down-regulated, and HLA-A2 Ags are selectively lost because of a single cytosine deletion in the HLA-A2 gene exon 4. Our results in conjunction with those in the literature suggest the emergence of a preferential beta(2)m gene mutation in melanoma cells following strong T cell-mediated immune selection. Furthermore, the presence of multiple HLA class I Ag defects within a tumor cell population may reflect the accumulation of multiple escape mechanisms developed by melanoma cells to avoid distinct sequential T cell-mediated selective events.
authors.affiliation: Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: Chien-Chung
authors.initials: CC
authors.lastname: Chang
authors.forename: Michael
authors.initials: M
authors.lastname: Campoli
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Restifo
authors.forename: Xinhui
authors.initials: X
authors.lastname: Wang
authors.forename: Soldano
authors.initials: S
authors.lastname: Ferrone
mesh_terms: D000595:Amino Acid Sequence; D017951:Antigen Presentation / Q000235:genetics*; D001483:Base Sequence; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics* / Q000276:immunology; D000939:Epitopes / Q000096:biosynthesis / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D015234:HLA-A Antigens / Q000096:biosynthesis / Q000235:genetics; D015789:HLA-A2 Antigen / Q000096:biosynthesis / Q000235:genetics*; D015235:HLA-B Antigens / Q000096:biosynthesis / Q000235:genetics; D015236:HLA-C Antigens / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007167:Immunotherapy; D019656:Loss of Heterozygosity; D008545:Melanoma / Q000235:genetics* / Q000276:immunology* / Q000556:secondary; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D017354:Point Mutation; D021122:Protein Subunits / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D019139:Tumor Escape / Q000235:genetics / Q000276:immunology; D001613:beta 2-Microglobulin / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D018076:DNA, Complementary; D000939:Epitopes; D015234:HLA-A Antigens; C435939:HLA-A*02:01 antigen; D015789:HLA-A2 Antigen; D015235:HLA-B Antigens; D015236:HLA-C Antigens; C105787:MART-1-Melan-A(27-35) epitope; D009363:Neoplasm Proteins; D021122:Protein Subunits; D001613:beta 2-Microglobulin