[Microvessel count and vascular endothelial growth factor in renal cell carcinoma]

Angiogenesis plays an important role in the growth of solid tumors. The objective of this study is to investigate the relationship between microvessel density and mRNA measurement for vascular endothelial growth factor (VEGF) as well as the kinase domain receptor (KDR) in renal cell carcinoma (RCC).

From 1992 to 1994, expression of mRNAs of VEFG, KDR and microvessel count by Factor VIII immunohistochemical staining were examined in 22 cases of RCC.

Northern blot hybridization demonstrated that 18 tumors (82%) expressed a higher level of VEGF gene than corresponding normal renal tissues (T/N > 1) and that the expression of VEGF gene in the tumors correlated well with that of KDR gene (r = 0.780, p = 0.001). Most of the tumor cells positively reacted to immunohistochemical staining for VEGF, but all of the normal renal tissue elements did not. RT-PCR analysis revealed that mRNAs of VEGF expressed in the tumors were of soluble subclasses. The mean number of microvessels (< 50 micrometers in diameter) in the tumors was 62.7 +/- 39.1/mm2 (range 13.7-133.1) and significantly correlated with the expression of VEGF gene (r = 0.636, p = 0.001).

The results indicate that RCC cells actively produce soluble VEGF and strongly suggest that VEGF and its receptor KDR cooperate to enhance the angiogenesis of this tumor.