title: High-grade clear cell renal cell carcinoma has a higher angiogenic activity than low-grade renal cell carcinoma based on histomorphological quantification and qRT-PCR mRNA expression profile.
abstract: Clear cell renal cell carcinoma (CC-RCC) is a highly vascularised tumour and is therefore an attractive disease to study angiogenesis and to test novel angiogenesis inhibitors in early clinical development. Endothelial cell proliferation plays a pivotal role in the process of angiogenesis. The aim of this study was to compare angiogenesis parameters in low nuclear grade (n=87) vs high nuclear grade CC-RCC (n=63). A panel of antibodies was used for immunohistochemistry: CD34/Ki-67, carbonic anhydrase IX, hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF). Vessel density (MVD - microvessel density), endothelial cell proliferation fraction (ECP%) and tumour cell proliferation fraction (TCP%) were assessed. mRNA expression levels of angiogenesis stimulators and inhibitors were determined by quantitative RT-PCR. High-grade CC-RCC showed a higher ECP% (P=0.049), a higher TCP% (P=0.009), a higher VEGF protein expression (P<0.001), a lower MVD (P< 0.001) and a lower HIF-1alpha protein expression (P=0.002) than low-grade CC-RCC. Growth factor mRNA expression analyses revealed a higher expression of angiopoietin 2 in low-grade CC-RCC. Microvessel density and ECP% were inversely correlated (Rho=-0.26, P=0.001). Because of the imperfect association of nuclear grade and ECP% or MVD, CC-RCC was also grouped based on low/high MVD and ECP%. This analysis revealed a higher expression of vessel maturation and stabilisation factors (placental growth factor, PDGFB1, angiopoietin 1) in CC-RCC with high MVD, a group of CC-RCC highly enriched in low nuclear grade CC-RCC, with low ECP%. Our results suggest heterogeneity in angiogenic activity and vessel maturation of CC-RCC, to a large extent linked to nuclear grade, and, with probable therapeutic implications.
authors.affiliation: Angiogenesis Laboratory, Department of Pathology, Research Institute for Growth and Development (GROW), Maastricht University & University Hospital Maastricht, Maastricht NL 6229 HX, The Netherlands. mbald@lpat.azm.nl
authors.forename: M M
authors.initials: MM
authors.lastname: Baldewijns
authors.forename: V L
authors.initials: VL
authors.lastname: Thijssen
authors.forename: G G
authors.initials: GG
authors.lastname: Van den Eynden
authors.forename: S J
authors.initials: SJ
authors.lastname: Van Laere
authors.forename: A M
authors.initials: AM
authors.lastname: Bluekens
authors.forename: T
authors.initials: T
authors.lastname: Roskams
authors.forename: H
authors.initials: H
authors.lastname: van Poppel
authors.forename: A P
authors.initials: AP
authors.lastname: De Bruïne
authors.forename: A W
authors.initials: AW
authors.lastname: Griffioen
authors.forename: P B
authors.initials: PB
authors.lastname: Vermeulen
mesh_terms: D000368:Aged; D002292:Carcinoma, Renal Cell / Q000098:blood supply* / Q000235:genetics* / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D007680:Kidney Neoplasms / Q000098:blood supply* / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D042461:Vascular Endothelial Growth Factor A