Quantification of 11C-methionine uptake during proliferation of cultured human cancer cells

It has been reported that 11C-methionine (Met) is taken up in greater amounts when tumor cells are actively proliferating. This observation suggests that Met uptake depends on the cell cycle. This study was aimed at investigating the relationship between the cell cycle of cultured human cancer cells and Met uptake, and obtaining basic information for Met PET interpretation. HeLa S3 cells were synchronized by the double thymidine block method, and the relationship between cells synchronized at each phase and Met uptake was investigated during 14 hours after release. As a result, Met uptake was 73% of the peak level in the early S-phase immediately after release, gradually increased, and peaked in the early G2/M phase. Subsequently, Met uptake steeply declined over the late G2/M phase to 44% in the G1 phase. These results indicate that Met uptake depends on the cell cycle: Met accumulates highly from the S through G2/M phases and maximally in the G2 phase. Met PET seems to produce images reflecting the mitotic index of tumor cells, and predicts that more rapidly progressing malignant tumors will show a higher Met uptake. (author)