Rodríguez, TeresaMéndez, RosaCampo, Ana DelJiménez, PilarAptsiauri, NataliaGarrido, FedericoRuiz-Cabello, Francisco2012-11-122012-11-122007-02-23Rodríguez T, Méndez R, Campo A Del, Jiménez P, Aptsiauri N, Garrido, et al. Distinct mechanisms of loss of IFN-gamma mediated HLA class I inducibility in two melanoma cell lines.BMC Cancer. 2007 Feb 23;7:34.http://hdl.handle.net/10668/616Journal Article; Research Support, Non-U.S. Gov't;BACKGROUND The inability of cancer cells to present antigen on the cell surface via MHC class I molecules is one of the mechanisms by which tumor cells evade anti-tumor immunity. Alterations of Jak-STAT components of interferon (IFN)-mediated signaling can contribute to the mechanism of cell resistance to IFN, leading to lack of MHC class I inducibility. Hence, the identification of IFN-gamma-resistant tumors may have prognostic and/or therapeutic relevance. In the present study, we investigated a mechanism of MHC class I inducibility in response to IFN-gamma treatment in human melanoma cell lines. METHODS Basal and IFN-induced expression of HLA class I antigens was analyzed by means of indirect immunofluorescence flow cytometry, Western Blot, RT-PCR, and quantitative real-time RT-PCR (TaqMan(R) Gene Expression Assays). In demethylation studies cells were cultured with 5-aza-2'-deoxycytidine. Electrophoretic Mobility Shift Assay (EMSA) was used to assay whether IRF-1 promoter binding activity is induced in IFN-gamma-treated cells. RESULTS Altered IFN-gamma mediated HLA-class I induction was observed in two melanoma cells lines (ESTDAB-004 and ESTDAB-159) out of 57 studied, while treatment of these two cell lines with IFN-alpha led to normal induction of HLA class I antigen expression. Examination of STAT-1 in ESTDAB-004 after IFN-gamma treatment demonstrated that the STAT-1 protein was expressed but not phosphorylated. Interestingly, IFN-alpha treatment induced normal STAT-1 phosphorylation and HLA class I expression. In contrast, the absence of response to IFN-gamma in ESTDAB-159 was found to be associated with alterations in downstream components of the IFN-gamma signaling pathway. CONCLUSION We observed two distinct mechanisms of loss of IFN-gamma inducibility of HLA class I antigens in two melanoma cell lines. Our findings suggest that loss of HLA class I induction in ESTDAB-004 cells results from a defect in the earliest steps of the IFN-gamma signaling pathway due to absence of STAT-1 tyrosine-phosphorylation, while absence of IFN-gamma-mediated HLA class I expression in ESTDAB-159 cells is due to epigenetic blocking of IFN-regulatory factor 1 (IRF-1) transactivation.enHLA AntigensIRF1 protein, humanInterferon Regulatory Factor-1STAT1 Transcription FactorSTAT1 protein, humanInterferon-gammaInterferón gammaMelanomaFosforilación OxidativaFactor de Transcripción STAT1Transducción de SeñalNeoplasias CutáneasActivación TranscripcionalCélulas Tumorales CultivadasAntineoplastic AgentsMedical Subject Headings::Phenomena and Processes::Genetic Phenomena::Genetic Processes::Gene Expression Regulation::Epigenesis, GeneticMedical Subject Headings::Phenomena and Processes::Genetic Phenomena::Genetic Structures::Genome::Genome Components::Genes::Major Histocompatibility Complex::Genes, MHC Class IMedical Subject Headings::Chemicals and Drugs::Biological Factors::Antigens::Antigens, Surface::Histocompatibility Antigens::HLA AntigensMedical Subject Headings::Organisms::Eukaryota::Animals::Chordata::Vertebrates::Mammals::Primates::Haplorhini::Catarrhini::Hominidae::HumansMedical Subject Headings::Chemicals and Drugs::Amino Acids, Peptides, and Proteins::Peptides::Intracellular Signaling Peptides and Proteins::Adaptor Proteins, Signal Transducing::Interferon Regulatory Factors::Interferon Regulatory Factor-1Medical Subject Headings::Chemicals and Drugs::Amino Acids, Peptides, and Proteins::Peptides::Intercellular Signaling Peptides and Proteins::Cytokines::Interferons::Interferon-gammaMedical Subject Headings::Diseases::Neoplasms::Neoplasms by Histologic Type::Nevi and Melanomas::MelanomaMedical Subject Headings::Phenomena and Processes::Chemical Phenomena::Biochemical Phenomena::Biochemical Processes::PhosphorylationMedical Subject Headings::Chemicals and Drugs::Amino Acids, Peptides, and Proteins::Peptides::Intracellular Signaling Peptides and Proteins::Adaptor Proteins, Signal Transducing::STAT Transcription Factors::STAT1 Transcription FactorMedical Subject Headings::Phenomena and Processes::Chemical Phenomena::Biochemical Phenomena::Biochemical Processes::Signal TransductionMedical Subject Headings::Diseases::Neoplasms::Neoplasms by Site::Skin NeoplasmsMedical Subject Headings::Phenomena and Processes::Genetic Phenomena::Genetic Processes::Gene Expression Regulation::Transcriptional ActivationMedical Subject Headings::Phenomena and Processes::Genetic Phenomena::Genetic Processes::Gene Expression Regulation::Epigenesis, GeneticMedical Subject Headings::Chemicals and Drugs::Chemical Actions and Uses::Pharmacologic Actions::Therapeutic Uses::Antineoplastic Agentsresearch article17319941open access10.1186/1471-2407-7-341471-2407PMC1808467