title: Markedly decreased expression of TAP1 and LMP2 genes in HLA class I-deficient human tumor cell lines.
abstract: HLA class I antigens of the human major histocompatibility complex play an important role in immune response. These molecules present foreign antigenic peptides to cytotoxic T lymphocytes and thereby play a role in the immune surveillance of cells infected with virus or other intracellular pathogens or altered by malignant transformation. A marked deficiency or lack of expression of these antigens has been reported in a variety of human neoplasms. In the present study, we examined the expression of class I alpha chain, beta 2-microglobulin, TAP (TAP1 and TAP2) and LMP (LMP2 and LMP7) genes in a number of human tumor cell lines including small-cell lung carcinoma, hepatocellular carcinoma, colon adenocarcinoma and basophilic leukaemia. These cell lines were deficient in expression of both class I alpha chain and beta 2-microglobulin gene products. In addition, these cell lines lacked the products of MHC-encoded proteasome subunit LMP2 as well as the putative peptide transporter TAP1 genes. In contrast, TAP2 and LMP7 genes were expressed in these cell lines. Treatment of cells with gamma-IFN markedly enhanced the expression of class I alpha chain, beta 2-microglobulin, TAP1 and LMP2 genes with a concomitant increase in cell-surface expression of class I molecules. The upregulation of TAP1 and LMP2 expression is associated with increased class I expression, suggesting that endogenous antigens, e.g. tumor antigens, could be presented by class I molecules following treatment of tumor cells with gamma-IFN.
authors.affiliation: Department of Pathology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: D P
authors.initials: DP
authors.lastname: Singal
authors.forename: M
authors.initials: M
authors.lastname: Ye
authors.forename: J
authors.initials: J
authors.lastname: Ni
authors.forename: D P
authors.initials: DP
authors.lastname: Snider
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D003546:Cysteine Endopeptidases; D015536:Down-Regulation; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D009097:Multienzyme Complexes; D009369:Neoplasms / Q000235:genetics / Q000276:immunology*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000235:genetics*; D014407:Tumor Cells, Cultured; D001613:beta 2-Microglobulin / Q000378:metabolism
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D015395:Histocompatibility Antigens Class I; D009097:Multienzyme Complexes; D011506:Proteins; C073119:TAP1 protein, human; D001613:beta 2-Microglobulin; C071313:LMP-2 protein; C071692:TAP2 protein, human; D003546:Cysteine Endopeptidases; C077436:LMP7 protein; D046988:Proteasome Endopeptidase Complex