Preliminary results comparing the recovery of basic fibroblast growth factor (FGF-2) in adipose tissue and benign and malignant renal tissue

Purpose: Basic fibroblast growth factor (bFGF or FGF-2) is mitogenic to numerous epithelial, mesodermal and endothelial cells, and thus may play a role in the neovascularity and progression of several tumors. Furthermore, FGF-2 is reported to be elevated in the serum and urine of patients with various cancers, including renal cancer. Obesity, with increased body fat, is a risk factor for renal cancer through unknown mechanisms. Since adipose tissue is a source of FGF-8, we determined the quantity and quality of activity of FGF-2 in omental adipose tissue and compared it to normal and cancerous renal tissue. Materials and Methods: Using heparin-Sepharose chromatography we extracted proteins from human omental adipose tissue, renal cell carcinoma (RCC) and benign renal tissue (BRT). Using FGF-2 antisera we performed western blot analysis to confirm their homology to FGF-2. We also assessed recovery, mitogenicity and angiogenicity of each of the proteins using thymidine incorporation into human umbilical vein endothelial cells (HUVEC) and the chorioallantoic membrane (CAM) assay. Results: Each of the three purified mitogenic proteins eluted with NaCl concentrations between 1.4 M. and 1.8 M., similar to control FGF-2. There was greater recovery of FGF-2 from omental adipose tissue compared with renal cell carcinoma or benign renal tissue (42 mu g. vs. 24 mu g. and 18 mu g., respectively; ANOVA p < 0.05). Moreover, FGF-2 from adipose tissue had greater mitogenic activity (96.% versus 68% and 38%; p < 0.05) and greater angiogenic activity (5.5 vessels versus 2.7 and 1.6 vessels; p < 0.05) on the CAM assay. Conclusions: We suggest that human omental adipose tissue FGF-2 may demonstrate greater mitogenic and angiogenic activity than either benign or cancerous renal tissue FGF-2. It is not known if FGF-2 from adipose tissue may play a role in the relationship between obesity and renal cancer.