ECE2007 Poster Presentations (1) (659 abstracts)
18FDG-PET is based on the capability of tumor cells to take up glucose. An increment in expression of the glucose transporter 1 (GLUT1) has been observed in thyroid tumors with poor prognosis but very few data are available about the expression of other glucose transporters in thyroid. Here, we study the expression and function of GLUT isoforms 1, 2, 3, 4, 6, 8, 10, 12 in human thyroid carcinoma cell lines ARO and FRO (anaplastic carcinoma), NPA (poorly-differentiated papillary carcinoma), WRO (follicular carcinoma) and TT (medullary carcinoma). We studied expression of GLUTs by conventional and quantitative RT-PCR, we evaluated cell 2-Deoxy-D-[3H]-glucose uptake and we studied GLUT1 protein on cell membrane fractions. We confirmed that GLUT1 is the predominant isoform in thyroid carcinoma with higher expression in ARO and FRO. By contrast, GLUT3 expression is lower in these two cell lines but comparable to GLUT1 in WRO, NPA and TT. GLUT4 and GLUT10 are barely expressed in all cell lines. We also observed GLUT6 and GLUT8 expression in all cell lines and GLUT12 in ARO, TT and FRO. Western blot shows GLUT1 protein in ARO and FRO membrane fractions. All lines studied but TT display different levels of glucose uptake; surprisingly, NPA and WRO uptake is higher than in ARO and FRO although these latter show higher levels of GLUT1 expression. In conclusion, we confirm that GLUT1 is the predominant form in thyroid tumors but other isoforms can be present and its protein is abundant in anaplastic carcinoma cell membranes. Medullary carcinoma cell line TT, despite the expression of some GLUT isoforms, is not able to take up glucose. Finally, the high rate of glucose uptake observed in NPA and WRO could be justified by presence of other forms of GLUT not considered in this study.