title: Matrix metalloproteinase-9 is required for vasculogenic mimicry by clear cell renal carcinoma cells.
abstract: BACKGROUND
  Vasculogenic mimicry (VM), a new pattern of tumor microcirculation system, has been proved to be important for tumor growth and progression and may be one of the causes of antiangiogenesis resistance. Matrix metalloproteinase-9 (MMP9) was shown to correlate with VM formation in some other cancers. However, the relationship between VM formation and MMP9 in renal cell carcinoma (RCC) has not been determined.
  
  
  METHODS
  The VM formation and MMP9 expressions were analyzed by CD34/periodic acid-Schiff dual staining and immunohistochemistry in 119 RCC specimens. We used a well-established 3-dimention culture model to compare VM formation in 786-O, 769-P, and HK-2 cell lines in vitro. MMP9 expressions on either messenger RNA or protein levels were compared among the cell lines by quantitative polymerase chain reaction or Western blot. To determine further the relationship between MMP9 and VM in RCC, 786-O and 769-P were treated with specific MMP9 inhibitor or small interfering RNA. VM formation, cell migration, and invasion were subsequently assessed by 3-dimention culture, wound-healing, and transwell assays.
  
  
  RESULTS
  Immunohistochemistry demonstrated both VM formation and MMP9 overexpression were positively associated with clinical staging, pathological grade, and metastasis (P<0.01). VM formation was closely correlated with MMP9 overexpression in RCC (r = 0.602, P<0.01). Lower MMP9 expression level was observed in normal kidney cell line HK-2, which was unable to form VM on Matrigel, whereas higher expression of MMP9 was found in VM-forming cancer cell lines 786-O and 769-P. Inhibition of MMP9 not only disrupted VM formation in 786-O and 769-P but also reduced cell migration and invasion.
  
  
  CONCLUSIONS
  These results indicate an intimate relationship between MMP9 overexpression and VM formation in RCC. Treatments targeting VM formation by inhibiting the activity of MMP9 could be beneficial in RCC therapy.
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Lin
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Jin-cheng
authors.initials: JC
authors.lastname: Pan
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Fa-ming
authors.initials: FM
authors.lastname: Zhang
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Jin-tao
authors.initials: JT
authors.lastname: Zhuang
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Cheng-qiang
authors.initials: CQ
authors.lastname: Mo
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China. Electronic address: wangdaoh@mail.sysu.edu.cn.
authors.forename: Dao-hu
authors.initials: DH
authors.lastname: Wang
authors.affiliation: Department of Urology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China. Electronic address: qiushp@mail.sysu.edu.cn.
authors.forename: Shao-peng
authors.initials: SP
authors.lastname: Qiu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000098:blood supply / Q000201:enzymology / Q000473:pathology*; D045744:Cell Line, Tumor; D002648:Child; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000098:blood supply / Q000201:enzymology / Q000473:pathology*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000201:enzymology / Q000473:pathology*; D016133:Polymerase Chain Reaction; D055815:Young Adult
chemical_list: C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9
keywords: Invasion; Matrix metalloproteinase-9; Metastasis; Migration; Renal cell carcinoma; Vasculogenic mimicry