Identification of CCAAT displacement protein (CDP/cut) as a locus-specific repressor of major histocompatibility complex gene expression in human tumor cells.
Human major histocompatibility (MHC) class I antigen expression is important in controlling the metastatic growth of malignant tumors. Locus-specific down-regulation of MHC class I gene expression is frequently observed in human tumors, leading to decreased susceptibility to cytotoxic T-cell-mediated lysis. The mechanism of this down-regulation is incompletely understood. Here, we describe the identification of human CCAAT displacement protein (CDP/cut) as a locus-specific repressor of HLA-B and C gene expression. Transient and stable transfections in HeLa and K562 cells demonstrated the presence of a repressor element 650 base pairs upstream of the first exon of HLA-B7. A specific binding complex with the HLA-B7 and Cw2 repressor elements was demonstrated by EMSA. Formation of the EMSA complex was inhibited specifically with polyclonal antiserum to human CDP/cut, demonstrating that CDP/cut binds the HLA-B7 repressor element. The corresponding region of the HLA-A2 promoter neither repressed HLA-A2 gene expression nor bound CDP/cut. Overexpression of CDP/cut in cell lines deficient in CDP/cut resulted in a nearly 4-fold repression of reporter constructs containing the HLA-B7 repressor element but not the corresponding region of the HLA-A2 promoter. Repression of HLA-B and C gene expression by CDP/cut does not involve displacement of NF-Y, nor is CDP/cut associated with the histone deacetylase HDAC1 when bound to the HLA-B7 repressor element. To our knowledge, these results identify CDP/cut as the first example of a locus-specific repressor of MHC class I gene transcription in human tumor cells.
Snyder
S R
SR
Massey Cancer Center, Medical College of Virginia at Virginia Commonwealth University, Richmond, VA 23298, USA. ssnyder@hsc.vcu.edu
Wang
J
J
Waring
J F
JF
Ginder
G D
GD
D001665:Binding Sites; D023081:CCAAT-Binding Factor / Q000378:metabolism; D015536:Down-Regulation; D005805:Genes, MHC Class I; D017930:Genes, Reporter; D015789:HLA-A2 Antigen / Q000235:genetics; D015793:HLA-B7 Antigen / Q000235:genetics; D006367:HeLa Cells; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism; D018398:Homeodomain Proteins; D006801:Humans; D020014:K562 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors; D015533:Transcriptional Activation; D014162:Transfection
D023081:CCAAT-Binding Factor; C080632:CUX1 protein, human; D015789:HLA-A2 Antigen; D015793:HLA-B7 Antigen; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases