FDG uptake and glucose transporter subtype expressions in experimental tumor and inflammation models

Although FDG uptake is closely related to the expression of the glucose tra nsporter (GLUT) in malignant tumors, such a relationship has not been fully investigated in inflammatory lesions. The aim of our study was to determin e the expression of GLUT subtypes in experimental inflammatory lesions and to compare the results with those in malignant tumors in relation to FDG ac cumulation. Methods: Rats were inoculated with a suspension of Staphylococc us aureus or allogenic hepatoma cells (KDH-8) into the left calf muscle. Fi ve days after S. aureus inoculation (n = 9) and 14 d after KDH-8 inoculatio n (n = 11), [C-14]FDG was Injected intravenously and its accumulation in th e infectious and tumor tissues was determined as the percentage activity of the injected dose per gram of tissue (%ID/g). The expression of glucose tr ansporters (GLUT-1 to GLUT-5) was investigated by immunostaining the infect ious tissues (n = 6) and the tumor tissues (n = 6). Immunohistochemical gra ding was assessed semiquantitatively by 5 observers. Results: The [14C]FDG uptake was significantly higher in the tumor lesion than in the inflammator y lesion (2.04 +/- 0.38 %ID/g vs. 0.72 +/- 0.15 %ID/g; P < 0.0001). The tum or and inflammatory tissues highly expressed GLUT-1 and GLUT-3. The GLUT-1 expression level was significantly higher in the tumor tissue than in the i nflammatory tissue (P < 0.05). Conclusion: The results based on our models showed a high FDG uptake and high GLUT-1 expression level not only in the t umor lesion but also in the inflammatory lesion. The higher GLUT-1 expressi on level In the tumor lesion may partially explain the higher FDG accumulat ion in the tumor than in the inflammatory lesion.