Relationship between vascular endothelial growth factor and nuclear factor-κB in renal cell tumors

Abstract

Aim: To assess the relationship between protein and messenger RNA (mRNA) levels of vascular endothelial growth factor (VEGF) and subcellular localization of nuclear factor-kappa B (NF-κB), proliferation rate of tumor cells, and clinicopathological characteristics of renal cell tumors. Methods: We analyzed 31 one renal cell tumors - 22 clear cell renal cell carcinomas (CCRCC) and 9 other histologic types (non-CCRCC). VEGF expression and subcellular localization of p65 member of NF-κB and Ki67 were immunohistochemically evaluated for the proliferation rate of tumor cells. Expression of VEGF mRNA was assessed using quantitative real-time polymerase chain reaction after total RNA extraction from snap-frozen tumor tissue samples. Results: Cytoplasmic localization of VEGF protein in renal cell tumors showed a perimembranous and diffuse pattern, the former being more evident in CCRCC (27.1 ± 18.9 vs 3.3 ± 10 % tumors, P<0.001) and the latter in non-CCRCC type (71.7 ± 23.2 vs 31.1 ± 22.1 % tumors, P < 0.001). Heterogeneity in VEGF gene expression was more pronounced in CCRCC type than in non-CCRCC type (P = 0.004). In addition, perimembranous VEGF pattern was associated with higher VEGF mRNA levels (P = 0.006) and diffuse VEGF pattern with lower VEGF mRNA levels (P < 0.001). Nuclear and cytoplasmic staining of NF-κB/p65 was observed in the majority of tumor cells. A significant association was recorded between cytoplasmic NK-κB/65 staining and VEGF staining of diffuse pattern (P = 0.026). Association between NF-κB/65 and proliferation rate of tumor cells was significant for cytoplasmic staining (P = 0.039) but not for nuclear NFkB/p65 staining (P = 0.099). Conclusion: Higher but inhomogeneous expression of VEGF in tumor cells, especially in CCRCCs, is associated with NF-κB/65 activity. This indicates that both VEGF and NF-κB/65 may be important in renal carcinogenesis, representing a possible molecular target in the treatment of renal cell carcinoma.