The high rate of glucose uptake to fuel the bioenergetic and anabolic demands of proliferating cancer cells is well recognized and is exploited with 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG- PET) to image tumors clinically. In contrast, enhanced glucose storage as glycogen (glycogenesis) in cancer is less well understood and the availability of a noninvasive method to image glycogen in vivo could provide important biologic insights. Here, we demonstrate that 18F-N-(methyl-(2-fluoroethyl)-1H-[1,2,3] triazole-4-yl)glucosamine (18F-NFTG) annotates glycogenesis in cancer cells and tumors in vivo, measured by PET. Specificity of glycogen labeling was demonstrated by isolating 18F-NFTG-associated glycogen and with stable knockdown of glycogen synthase 1, which inhibited 18F-NFTG uptake, whereas oncogene (Rab25) activation-associated glycogen synthesis led to increased uptake. We further show that the rate of glycogenesis is cell-cycle regulated, enhanced during the nonproliferative state of cancer cells. We demonstrate that glycogen levels, 18F-NFTG, but not 18F-FDG uptake, increase proportionally with cell density and G1-G0 arrest, with potential application in the assessment of activation of oncogenic pathways related to glycogenesis and the detection of posttreatment tumor quiescence.
ASJC Scopus subject areas
- Cancer Research