title: Chemokine receptor CXCR7 regulates the invasion, angiogenesis and tumor growth of human hepatocellular carcinoma cells.
abstract: BACKGROUND
  In spite of recent advances in diagnostic and therapeutic measures, the prognosis of hepatocellular carcinoma (HCC) patients remains poor. Therefore, it is crucial to understand what factors are involved in promoting development of HCC. Evidence is accumulating that members of the chemokine receptor family are viewed as promising therapeutic targets in the fight against cancer. More recent studies have revealed that chemokine receptor CXCR7 plays an important role in cancer development. However, little is known about the effect of CXCR7 on the process of HCC cell invasion and angiogenesis. The aim of this study is to investigate the expression of CXCR7 in hepatocellular carcinoma tissues and cell lines and to evaluate the role of CXCR7 in tumor growth, angiogenesis and invasion of HCC cells.
  
  
  METHODS
  We constructed CXCR7 expressing shRNA, and CXCR7shRNA was subsequently stably transfected into human HCC cells. We evaluated the effect of CXCR7 inhibition on cell invasion, adhesion, VEGF secretion, tube formation and tumor growth. Immunohistochemistry was done to assess the expression of CXCR7 in human hepatocellular carcinoma tissues and CD31 in tumor of mice. We also evaluated the effect of VEGF stimulation on expression of CXCR7.
  
  
  RESULTS
  CXCR7 was overexpressed in hepatocellular carcinoma tissues. We showed that high invasive potential HCC cell lines express high levels of CXCR7. In vitro, CXCL12 was found to induce invasion, adhesion, tube formation, and VEGF secretion in SMMC-7721 cells. These biological effects were inhibited by silencing of CXCR7 in SMMC-7721 cells. In addition, we also found that VEGF stimulation can up-regulate CXCR7 expression in SMMC-7721 cells and HUVECs. More importantly, enhanced expression of CXCR7 by VEGF was founctional. In vivo, tumor growth and angiogenesis were suppressed by knockdown of CXCR7 in SMMC-7721 cells. However, silencing of CXCR7 did not affect metastasis of tumor in vivo.
  
  
  CONCLUSIONS
  Increased CXCR7 expression was found in hepatocellular carcinoma tissues. Knockdown of CXCR7 expression by transfected with CXCR7shRNA significantly inhibits SMMC-7721 cells invasion, adhesion and angiogenesis. Finally, down-regulation of CXCR7 expression lead to a reduction of tumor growth in a xenograft model of HCC. This study provides new insights into the significance of CXCR7 in invasion and angiogenesis of HCC.
authors.affiliation: Department of Endocrine Surgery and breast cancer centre, the First Affiliated Hospital, Chongqing Medical University, Chongqing, PR China.
authors.forename: Ke
authors.initials: K
authors.lastname: Zheng
authors.forename: Hong-Yuan
authors.initials: HY
authors.lastname: Li
authors.forename: Xin-Liang
authors.initials: XL
authors.lastname: Su
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Wang
authors.forename: Tian
authors.initials: T
authors.lastname: Tian
authors.forename: Fan
authors.initials: F
authors.lastname: Li
authors.forename: Guo-Sheng
authors.initials: GS
authors.lastname: Ren
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008113:Liver Neoplasms / Q000473:pathology*; D008297:Male; D051379:Mice; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis; D054387:Receptors, CXCR / Q000096:biosynthesis*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C501896:ACKR3 protein, human; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D054387:Receptors, CXCR; D042461:Vascular Endothelial Growth Factor A