title: Tetraspanin Family Member, CD82, Regulates Expression of EZH2 via Inactivation of p38 MAPK Signaling in Leukemia Cells.
abstract: OBJECTIVE
  We recently found that the tetraspanin family member, CD82, which is aberrantly expressed in chemotherapy-resistant CD34(+)/CD38- acute myelogenous leukemia (AML) cells, negatively regulates matrix metalloproteinase 9, and plays an important role in enabling CD34(+)/CD38(-) AML cells to adhere to the bone marrow microenvironment. This study explored novel functions of CD82 that contribute to AML progression.
  
  
  METHODS
  We employed microarray analysis comparing the gene expression profiles between CD34(+)/CD38(-) AML cells transduced with CD82 shRNA and CD34(+)/CD38(-) AML cells transduced with control shRNA. Real-time RT-PCR and western blot analysis were performed to examine the effect of CD82 knockdown on the expression of the polycomb group member, enhancer of zeste homolog 2 (EZH2), in leukemia cells. A chromatin immunoprecipitation assay was performed to examine the effect of CD82 expression on the amount of EZH2 bound to the promoter regions of tumor suppressor genes in leukemia cells. We also utilized methylation-specific PCR to examine whether CD82 expression influences the methylation status of the tumor suppressor gene promoter regions in leukemia cells.
  
  
  RESULTS
  Microarray analysis revealed that levels of EZH2 decreased after shRNA-mediated depletion of CD82 in CD34(+)/CD38(-) AML cells. Moreover, the antibody-mediated blockade of CD82 in leukemia cells lowered EZH2 expression via activation of p38 MAPK signaling, decreased the amount of EZH2 bound to the promoter regions of the tumor suppressor genes, and inhibited histone H3 lysine 27 trimethylation in these promoter regions, resulting in upregulation of the tumor suppressors at both the mRNA and protein levels.
authors.affiliation: Department of hematology and Respiratory Medicine immunology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Nishioka
authors.affiliation: Department of hematology and Respiratory Medicine immunology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ikezoe
authors.affiliation: Department of immunology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan.
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of hematology and Respiratory Medicine immunology, Kochi Medical School, Kochi University, Nankoku, Kochi 783-8505, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Yokoyama
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000378:metabolism; D018952:Antigens, CD34 / Q000378:metabolism; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015536:Down-Regulation / Q000235:genetics; D000071221:Enhancer of Zeste Homolog 2 Protein; D004789:Enzyme Activation; D005260:Female; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic; D006657:Histones / Q000378:metabolism; D006801:Humans; D051861:Kangai-1 Protein / Q000235:genetics / Q000378:metabolism*; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology* / Q000235:genetics*; D008239:Lysine / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D008954:Models, Biological; D051059:PTEN Phosphohydrolase / Q000235:genetics; D063151:Polycomb Repressive Complex 2 / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D034741:RNA, Small Interfering / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D018952:Antigens, CD34; C497688:CD82 protein, human; D006657:Histones; D051861:Kangai-1 Protein; D034741:RNA, Small Interfering; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D048051:p38 Mitogen-Activated Protein Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D051997:ADP-ribosyl Cyclase 1; D008239:Lysine