Development of Imaging and Quantitation of Gene Induction and Expression using Nuclear Medicine Technique

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To evaluate the uptake of radiopharmaceuticals labeled with positron emitter in the brain tumor using positron emission tomography, in vitro evaluation of tracer uptake was examined. Firstly we performed [F-18] fluorodeoxyglucose (FDG) uptake in astrocytoma cell lines SW1088 and U-118MG. Uptake of FDG in these cell lines increased in a cell number dependent manner. The uptake of FDG in these cell lines was 26.7% and 32.5% at cell number of 15×10^4 and 21×10^4, respectively. Secondly amino-acid tracer [F-18] fluoromethyl tyrosine (FMT) was used. The uptake of FMT was 7.7% and 10.8% at cell number of 7.5×10^4 and 10.8×10^4, respectively. Tertiary we used [C-11] choline : precursor of phosphatidyl choline. The uptake in U-118MG was 11.2% at cell number of 17×10^4 and the uptake was temperature dependent. The results indicated that these cell lines accumulate positron emitter labeled biomarkers of glucose, amino acid and choline, and quantitative evaluation was possible.Clinical evaluation of these tracers was performed in cases with brain tumor. Although FDG is a representative tracer for the diagnosis of malignant tumors, its uptake is not specific for the malignant tumor. FMT and [C-11] choline may be also useful for the diagnosis in terms of cell proliferation and tumor malignancy.Based on these results the effect of gene therapy could be evaluated by the uptake of FDG as a tracer for glucose metabolism and also FAMT and [C-11] choline as tracers to correlate activity of tumor. Gene induction and evaluation of its expression could be evaluable by means of nuclear medicine technique.