HeLa S3細胞に対するFDGと⁶⁷Ga citrate集積の細胞周期依存性

抄録

Positron emission tomography using fluorine-18 fluoro-deoxyglucose (FDG PET) is useful for the detection of malignant tumor recurrences and for the evaluation of a therapeutic response to these;including ones found in the lung, colon, head and neck regions. The experimental study demonstrated FDG uptake was higher in faster-growing rather than in slower-growing tumors. These findings show FDG accumulation exhibits cell cycle dependency. However, the precise mechanism remains to be elucidated. In this study, the relationship between FDG uptake and the cell cycle phase in HeLa S3 cells, as well as how they compare to the conventional tracer ⁶⁷Ga citrate (Ga) with single photon emission tomography (SPECT) was assessed. Synchronization of HeLa S3 cells was accomplished via a double thymidine block. The uptake of FDG and Ga was determined after cell cycle synchronization. The glucose transporter was independently evaluated for the level of its Glut 1 glucose transporter membrane protein. FDG uptake in HeLa S3 cells was significantly higher in the early S phase and G₂/M phase compared to the G₁ phase. In addition, Ga uptake was higher in the G₂/M phase. Immunochemical assays for the Glut 1 transporter showed an increase in membrane expression within S phase cells. It has been concluded that cell cycle dependency is reflected in the uptake of FDG and Ga, seen during PET or SPECT imaging of tumor tissue. These results reveal tumor proliferative activity, and can assist in evaluating a therapeutic response. Furthermore, the increased FDG uptake, in part due to increased membrane expression of the Glut 1 glucose transporter, contributes to this phenomenon.