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5‐Azacytidine Increases Class I HLA ABC Expression in Tumor Cell Lines
Author(s) -
Long Patrick L,
Louis Cassandre L,
Nicholas David W.,
O'Donnell Robert W.
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.581.3
Subject(s) - dna methylation , flow cytometry , epigenetics , methyltransferase , carcinogenesis , cancer research , cell culture , biology , microbiology and biotechnology , human leukocyte antigen , antigen , methylation , chemistry , immunology , cancer , dna , biochemistry , genetics , gene expression , gene
MHC‐I expression is commonly down regulated during carcinogenesis due to the proliferative advantage acquired. Without class I MHC surface proteins, neoplastic cells are able to avoid surveillance of the adaptive immune system by preventing the presentation of endogenous antigens, providing a proliferative advantage. 5‐azacytidine is a novel epigenetic therapeutic drug that inhibits DNA methyltransferase through methyltransferase trapping. Tumor cells display global hypomethylation of their genome but specific hypermethylation of tumor suppressor CpG islands. We hypothesized that tumor cell lines treated with 5‐Azacytidine would display an increased amount of Class I HLA expression on their surface. To test this model we have begun to treat MCF‐7, MDA‐MB‐435, MDA‐MB‐231, A431 and HL‐60 tumor cell lines with relatively high and low doses of 5‐Azacytidine over a 48 or 72‐hour period. For the MDA‐MB 435 cell line we also compared long‐term exposure. Class I HLA‐ABC proteins were detected with a PE‐conjugated anti‐HLA‐ABC monoclonal antibody and fluorescence measured by flow cytometry. Preliminary results have shown an increase in expression in 5‐Azacytidine treated cells compared to controls but the magnitude of change varied among the cell lines tested. MDA‐MB‐435 cells treated with 5‐Azacytidine for more than six months showed the greatest change (mean fluorescence values of 785 in the untreated cells and 1180 for the 5‐azacytidine treated ). HL‐60 treated with 5‐Azacytidine for three weeks showed little to no change in fluorescence. Future experiments will optimize dose and length of exposure and attempt to identify methylated promoter regions in MHC via bisulfate conversion. With further experimentation, 5‐Azacytidine may prove to assist cancer immunotherapies where low MHC expression in tumor cells is encountered.