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 ¼ 87) vs high nuclear grade CC-RCC (n ¼ 63). A panel of antibodies was used for immunohistochemistry: CD34/Ki-67, carbonic anhydrase IX, hypoxia-inducible factor-1a (HIF-1a) 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 ¼ 0.049), a higher TCP% (P ¼ 0.009), a higher VEGF protein expression (Po0.001), a lower MVD (Po 0.001) and a lower HIF-1a protein expression (P ¼ 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 ¼ À0.26, P ¼ 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.

Complexity of tumor vasculature in clear cell renal cell carcinoma

“…As summarized in Table 1, higher MVD has been reported in many studies to be a favorable prognostic factor (eg, a higher blood vessel density in CCRCC is correlated with a better prognosis or longer patient survival). 4,[14][15][16][17][18][19][20][21][22] However, other studies have reported opposite results correlating higher MVD with poorer prognosis, [23][24][25][26][27][28] whereas others have been unable to find a significant prognostic role for MVD. [29][30][31][32][33] The controversy could result from many nonmechanistic factors, including sample size, sampling bias, the different blood vessel markers chosen for immunohistochemical (IHC) characterization, the quality of IHC staining, the methods of vasculature quantification, and the methods of interpretation.…”

The angiogenic makeup of human hepatocellular carcinoma does not favor vascular endothelial growth factor/angiopoietin-driven sprouting neovascularization

“…Although Ang-1 mRNA levels in the tumor were approximately 25% less compared with their levels in normal kidney tissue, Ang-2 mRNA was increased over 30-fold in the tumor. A similar shift in angiopoietin balance was recently reported in RCC by Baldewijns et al 16 Although mRNA levels of different genes cannot be directly compared, the change in Ang-1/-2 mRNA ratio implies a shift toward a vessel destabilization phenotype. The increased mRNA levels of Ang-2 in RCC were corroborated by western blot analysis, showing significant amounts of Ang-2 protein in this tumor type.…”

The Expression of Histone Demethylase JMJD1A in Renal Cell Carcinoma

“…JMJD1A is especially located around vessel of cancer tissue, which suggest that JMJD1A may be involved in VEGFA expression. The overexpression of VEGFA is beneficial for tumor angiogenesis and RCC is a highly vascularized cancer [19], so regulation of JMJD1A on VEGFA may be important for RCC development. …”