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

J Immunol. 2005 Feb 1;174(3):1462-71. doi: 10.4049/jimmunol.174.3.1462.

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Antigen Presentation / genetics*
  • Base Sequence
  • Cell Line, Transformed
  • Cell Line, Tumor
  • DNA, Complementary / genetics
  • Down-Regulation / genetics*
  • Down-Regulation / immunology
  • Epitopes / biosynthesis
  • Epitopes / genetics
  • Gene Expression Regulation, Neoplastic
  • HLA-A Antigens / biosynthesis
  • HLA-A Antigens / genetics
  • HLA-A2 Antigen / biosynthesis
  • HLA-A2 Antigen / genetics*
  • HLA-B Antigens / biosynthesis
  • HLA-B Antigens / genetics
  • HLA-C Antigens / biosynthesis
  • HLA-C Antigens / genetics
  • Humans
  • Immunotherapy*
  • Loss of Heterozygosity
  • Melanoma / genetics*
  • Melanoma / immunology*
  • Melanoma / secondary
  • Molecular Sequence Data
  • Neoplasm Proteins / biosynthesis
  • Neoplasm Proteins / genetics
  • Point Mutation*
  • Protein Subunits / biosynthesis
  • Protein Subunits / genetics
  • Transfection
  • Tumor Escape / genetics
  • Tumor Escape / immunology
  • beta 2-Microglobulin / genetics*
  • beta 2-Microglobulin / isolation & purification

Substances

  • DNA, Complementary
  • Epitopes
  • HLA-A Antigens
  • HLA-A*02:01 antigen
  • HLA-A2 Antigen
  • HLA-B Antigens
  • HLA-C Antigens
  • MART-1-Melan-A(27-35) epitope
  • Neoplasm Proteins
  • Protein Subunits
  • beta 2-Microglobulin