title: Effect of hypoxia on tissue factor pathway inhibitor expression in breast cancer.
abstract: ESSENTIALS: A hypoxic microenvironment is a common feature of tumors that may influence activation of coagulation. MCF-7 and SK-BR-3 breast cancer cells and breast cancer tissue samples were used. The results showed transcriptional repression of tissue factor pathway inhibitor expression in hypoxia. Hypoxia-inducible factor 1α may be a target for the therapy of cancer-related coagulation and thrombosis.
  
  
  BACKGROUND
  Activation of coagulation is a common finding in patients with cancer, and is associated with an increased risk of venous thrombosis. As a hypoxic microenvironment is a common feature of solid tumors, we investigated the role of hypoxia in the regulation of tissue factor (TF) pathway inhibitor (TFPI) expression in breast cancer.
  
  
  OBJECTIVE
  To explore the transcriptional regulation of TFPI by hypoxia-inducible factor (HIF)-1α in breast cancer cells and their correlation in breast cancer tissues.
  
  
  RESULTS
  MCF-7 and SK-BR-3 breast cancer cells were cultured in 1% oxygen or treated with cobalt chloride (CoCl2 ) to mimic hypoxia. Time-dependent and dose-dependent downregulation of TFPI mRNA (quantitative RT-PCR) and of free TFPI protein (ELISA) were observed in hypoxia. Western blotting showed parallel increases in the levels of HIF-1α protein and TF. HIF-1α inhibitor abolished or attenuated the hypoxia-induced downregulation of TFPI. Luciferase reporter assay showed that both hypoxia and HIF-1α overexpression caused strong repression of TFPI promoter activity. Subsequent chromatin immunoprecipitation and mutagenesis analysis demonstrated a functional hypoxia response element within the TFPI promoter, located at -1065 to -1060 relative to the transcriptional start point. In breast cancer tissue samples, gene expression analyses showed a positive correlation between the mRNA expression of TFPI and that of HIF-1α.
  
  
  CONCLUSIONS
  This study demonstrates that HIF-1α is involved in the transcriptional regulation of the TFPI gene, and suggests that a hypoxic microenvironment inside a breast tumor may induce a procoagulant state in breast cancer patients.
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Department of Hematology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: X Y
authors.initials: XY
authors.lastname: Cui
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.|Department of Medical Genetics, Oslo University Hospital, Oslo, Norway.
authors.forename: M
authors.initials: M
authors.lastname: Tinholt
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: B
authors.initials: B
authors.lastname: Stavik
authors.affiliation: Department of Hematology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.|Department of Hematology, Akershus University Hospital, Lørenskog, Norway.
authors.forename: A E A
authors.initials: AE
authors.lastname: Dahm
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.|Institute of Basal Medical Sciences, University of Oslo, Oslo, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Kanse
authors.affiliation: Department of Biosciences, University of Oslo, Oslo, Norway.
authors.forename: Y
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.|Institute of Basal Medical Sciences, University of Oslo, Oslo, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Seidl
authors.affiliation: Department of Research, Vestre Viken Hospital Trust, Drammen, Norway.|K. G. Jebsen Center for Breast Cancer Research, University of Oslo, Oslo, Norway.|Oslo Breast Cancer Research Consortium (OSBREAC), Oslo, Norway.
authors.forename: K K
authors.initials: KK
authors.lastname: Sahlberg
authors.affiliation: Department of Medical Genetics, Oslo University Hospital, Oslo, Norway.
authors.forename: N
authors.initials: N
authors.lastname: Iversen
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: G
authors.initials: G
authors.lastname: Skretting
authors.affiliation: Department of Hematology, Oslo University Hospital, Oslo, Norway.|Research Institute of Internal Medicine, Oslo University Hospital, Oslo, Norway.|Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors.forename: P M
authors.identifier: http://orcid.org/0000-0001-5556-8099
authors.initials: PM
authors.lastname: Sandset
mesh_terms: D000328:Adult; D000368:Aged; D001665:Binding Sites; D001777:Blood Coagulation; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015687:Cell Hypoxia; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D061986:MCF-7 Cells; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D059016:Tumor Microenvironment
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008074:Lipoproteins; D012333:RNA, Messenger; C051928:lipoprotein-associated coagulation inhibitor; D010100:Oxygen
keywords: HIF-1α protein; blood coagulation; breast cancer; human; hypoxia; tissue factor pathway inhibitor