title: Id1 enhances human ovarian cancer endothelial progenitor cell angiogenesis via PI3K/Akt and NF-κB/MMP-2 signaling pathways.
abstract: BACKGROUND
  Endothelial progenitor cells (EPCs) contribute to tumor angiogenesis and growth. We previously reported that over-expression of an inhibitor of DNA binding/differentiation 1 (Id1) in EPCs can enhance EPC proliferation, migration, and adhesion. In this study, we investigated the role of Id1 in EPC angiogenesis in patients with ovarian cancer and the underlying signaling pathway.
  
  
  METHODS
  Circulating EPCs from 22 patients with ovarian cancer and 15 healthy control subjects were cultured. Id1 and matrix metalloproteinase-2 (MMP-2) expression were analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blot. EPC angiogenesis was detected by tube formation assays. Double-stranded DNA containing the interference sequences was synthesized according to the structure of a pGCSIL-GFP viral vector and then inserted into a linearized vector. Positive clones were identified as lentiviral vectors that expressed human Id1 short hairpin RNA (shRNA).
  
  
  RESULTS
  Id1 and MMP-2 expression were increased in EPCs freshly isolated from ovarian cancer patients compared to those obtained from healthy subjects. shRNA-mediated Id1 down-regulation substantially reduced EPC angiogenesis and MMP-2 expression. Importantly, transfection of EPCs with Id1 in vitro induced phosphorylation of Akt (p-Akt) via phosphoinositide 3-kinase and increased the expression of MMP-2 via NF-κB. Blockage of both pathways by specific inhibitors (LY294002 and PDTC, respectively) abrogated Id1-enhanced EPC angiogenesis.
  
  
  CONCLUSIONS
  Id1 can enhance EPC angiogenesis in ovarian cancer, which is mainly mediated by the PI3K/Akt and NF-κB/MMP-2 signaling pathways. Id1 and its downstream effectors are potential targets for treatment of ovarian cancer because of their contribution to angiogenesis.
authors.affiliation: Department of clinical laboratory, the affiliated tumor hospital, Harbin Medical University, Harbin, China.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Su
authors.forename: Lingjuan
authors.initials: L
authors.lastname: Gao
authors.forename: Lichen
authors.initials: L
authors.lastname: Teng
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Jialin
authors.initials: J
authors.lastname: Cui
authors.forename: Shiyun
authors.initials: S
authors.lastname: Peng
authors.forename: Songbin
authors.initials: S
authors.lastname: Fu
mesh_terms: D000328:Adult; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1 / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism; D009389:Neovascularization, Pathologic; D010051:Ovarian Neoplasms / Q000378:metabolism*; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1; D016328:NF-kappa B; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2