title: Loss of expression of TIMP3 in clear cell renal cell carcinoma.
abstract: OBJECTIVE
  In clear cell renal cell carcinoma (CCRCC), vascular endothelial growth factor (VEGF) represents the central positive mediator of tumour angiogenesis while VEGF receptor (VEGFR) is the primary target of anti-angiogenic therapies. TIMP3 is a physiological VEGFR-2 antagonist and thus could be considered as an anti-angiogenic factor. We therefore determined the status of this physiological inhibitor in CCRCC.
  
  
  METHODS
  Archival tumour from 105 patients was studied. TIMP3 expression was analysed using immuno-histochemistry and real-time RT-PCR. Results were correlated with clinicopathological variables. To analyse the mechanisms of gene silencing involved, we performed Multiplex Ligation-dependent Probe Amplification (MLPA) and methylation-specific MLPA (MS-MLPA). At last, we evaluated the main upstream pathway described implicating TGFbetaRII, which induces TIMP3 expression.
  
  
  RESULTS
  A down-expression of TIMP3, determined by immunohistochemistry, affected 100/105 renal cancers (95.2%). TIMP3 mRNA levels were significantly lower in high-grade tumours. Loss of heterozygosity of the TIMP3 gene was observed in 8 tumours (7.6%) and the 5'CpG island of the TIMP3 promoter was found to be methylated in 25 tumours (23.8%). A down-expression of TGFbetaRII was found in 85/105 CCRCCs (80.9%). A significant correlation was found between TIMP3 expression and TGFbetaRII expression.
  
  
  CONCLUSIONS
  This is the first demonstration that the loss of TIMP3 expression is observed in almost all CCRCCs. This loss of expression is a common molecular event in CCRCC. It may be an important initiation step for tumour development in a complex process implicating loss of heterozygosity on chromosome 22q, promoter hyper-methylation and inactivation of the TGFbetaRII pathway.
authors.affiliation: CNRS UMR 6061, Institut de Génétique et Développement, Université Rennes 1, 35043 Rennes, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Masson
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rioux-Leclercq
authors.forename: Patricia
authors.initials: P
authors.lastname: Fergelot
authors.forename: Florence
authors.initials: F
authors.lastname: Jouan
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Mottier
authors.forename: Sandrine
authors.initials: S
authors.lastname: Théoleyre
authors.forename: Kalyane
authors.initials: K
authors.lastname: Bach-Ngohou
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Patard
authors.forename: Marc G
authors.initials: MG
authors.lastname: Denis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism*; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D055815:Young Adult
chemical_list: D009363:Neoplasm Proteins; D012333:RNA, Messenger; C088390:TIMP3 protein, human; D019717:Tissue Inhibitor of Metalloproteinase-3; D042461:Vascular Endothelial Growth Factor A