title: Scavenger chemokine (CXC motif) receptor 7 (CXCR7) is a direct target gene of HIC1 (hypermethylated in cancer 1).
abstract: The tumor suppressor gene HIC1 (Hypermethylated in Cancer 1) that is epigenetically silenced in many human tumors and is essential for mammalian development encodes a sequence-specific transcriptional repressor. The few genes that have been reported to be directly regulated by HIC1 include ATOH1, FGFBP1, SIRT1, and E2F1. HIC1 is thus involved in the complex regulatory loops modulating p53-dependent and E2F1-dependent cell survival and stress responses. We performed genome-wide expression profiling analyses to identify new HIC1 target genes, using HIC1-deficient U2OS human osteosarcoma cells infected with adenoviruses expressing either HIC1 or GFP as a negative control. These studies identified several putative direct target genes, including CXCR7, a G-protein-coupled receptor recently identified as a scavenger receptor for the chemokine SDF-1/CXCL12. CXCR7 is highly expressed in human breast, lung, and prostate cancers. Using quantitative reverse transcription-PCR analyses, we demonstrated that CXCR7 was repressed in U2OS cells overexpressing HIC1. Inversely, inactivation of endogenous HIC1 by RNA interference in normal human WI38 fibroblasts results in up-regulation of CXCR7 and SIRT1. In silico analyses followed by deletion studies and luciferase reporter assays identified a functional and phylogenetically conserved HIC1-responsive element in the human CXCR7 promoter. Moreover, chromatin immunoprecipitation (ChIP) and ChIP upon ChIP experiments demonstrated that endogenous HIC1 proteins are bound together with the C-terminal binding protein corepressor to the CXCR7 and SIRT1 promoters in WI38 cells. Taken together, our results implicate the tumor suppressor HIC1 in the transcriptional regulation of the chemokine receptor CXCR7, a key player in the promotion of tumorigenesis in a wide variety of cell types.
authors.affiliation: CNRS UMR 8161 Institut de Biologie de Lille, Université de Lille NORD de France, Institut Pasteur de Lille, 59017 Lille, France.
authors.forename: Capucine
authors.initials: C
authors.lastname: Van Rechem
authors.forename: Brian R
authors.initials: BR
authors.lastname: Rood
authors.forename: Majid
authors.initials: M
authors.lastname: Touka
authors.forename: Sébastien
authors.initials: S
authors.lastname: Pinte
authors.forename: Mathias
authors.initials: M
authors.lastname: Jenal
authors.forename: Cateline
authors.initials: C
authors.lastname: Guérardel
authors.forename: Keri
authors.initials: K
authors.lastname: Ramsey
authors.forename: Didier
authors.initials: D
authors.lastname: Monté
authors.forename: Agnès
authors.initials: A
authors.lastname: Bégue
authors.forename: Mario P
authors.initials: MP
authors.lastname: Tschan
authors.forename: Dietrich A
authors.initials: DA
authors.lastname: Stephan
authors.forename: Dominique
authors.initials: D
authors.lastname: Leprince
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D001483:Base Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D047369:Chromatin Immunoprecipitation; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D052138:Genes, Neoplasm; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D012516:Osteosarcoma / Q000235:genetics / Q000473:pathology; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D054387:Receptors, CXCR / Q000235:genetics* / Q000378:metabolism; D056564:Sirtuin 1; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism
chemical_list: C501896:ACKR3 protein, human; D004268:DNA-Binding Proteins; C499808:HIC1 protein, human; D051741:Kruppel-Like Transcription Factors; D012333:RNA, Messenger; D054387:Receptors, CXCR; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D037761:Sirtuins