Characterization of a near-infrared fluorescent DCPO-tagged glucose analogue for cancer cell imaging

Cancer cells are usually characterized with an increase in glucose uptake when compared with normal cells, which is known as Warburg effect. Near-infrared (NIR) fluorescent glucose analogues have been previously synthesized and been applied in cancer cell imaging. However, most NIR dyes usually have one or more charge in their structures, which may cause low cell membrane permeability and hamper their application in cell imaging. Here we reported a novel glucose analogue N2, which was designed and synthesized based on a new type of NIR dye, DCPO. As expected, higher level of N2 uptake was observed in hepatic carcinoma cells (HepG2) and gastric cancer cells (NCI-N87) than their equivalent cells from normal tissues of the same origin, respectively. The accumulation of N2 in cancer cells was in consistent with the overexpression of glucose transporter GLUT-1 in these cells. The cellular uptake of N2 was then confirmed to be dependent on GLUT-1, which was evidenced by the decreased uptake of N2 in the presence of d-glucose or GLUT-1 inhibitor phloretin. Moreover, uptake of N2 in cancer cells was found to be in a concentration- and time-dependent manner. In all, our study demonstrated that N2, as a novel DCPO-conjugated bioprobe, could be used to monitor cellular glucose consumption, and therefore might be applied in cancer cell bioimaging and bioassay in cancer studies.