Comparison of the tumorigenic potential of liver and kidney tumors induced by N-nitrosodimethylamine.

The aim of the study was to determine the tumorigenic potential of two cell lines established from N-nitrosodimethylamine induced rat hepatocarcinoma (HeDe) and mesenchymal renal tumors (NeDe). The basis of the distinction is that human cancers are known to overexpress facilitative GLUT transporters and TGF-beta1 protein. These proteins are linked to the increased metabolic energy consumption indicating uncontrolled growth and proliferation. We have assayed not only the expression of GLUT-1, GLUT-3 and TGF-beta1 proteins, but also the uptake of 2-fluoro-[18F]-2-deoxy-D-glucose (18FDG), a tracer for cancer diagnosis. Western blot analysis and whole body autoradiography were used to measure the 18FDG uptake of tumor cells. Elevated 18FDG uptake was measured in both tumor cell lines. Whole body autoradiography provided evidence that the uptake of 18FDG was lower in the necrotic inner part than in the more vascularized outer parts of primary hepatocarcinoma and mesenchymal renal tumors. GLUT-1 overexpression in hepatocarcinoma tumor, and high levels of GLUT-3 were found in the NeDe cell line and in the mesenchymal renal tumor. TGF-beta-1 was overexpressed in hepatocarcinoma and mesenchymal renal tumors. In vitro and in vivo parameters support the view that the tumorigenic potential of cancer cells cannot be determined by the expression of a single parameter such as the expression of either GLUT-1, GLUT-3 or 18FDG uptake. Besides the tumorigenic potential of the hepatocarcinoma, the high metabolic activity of the renal tumor indicated by its 18FDG uptake, GLUT-3 and TGF-beta1 expression, the mesenchymal renal tumor induced by N-nitroso-dimethylamine is not a benign, but an an aggressive renal carcinoma.