Fluorescent THF‐Based Fructose Analogue Exhibits Fructose‐Dependent Uptake

Abstract

Recent publications suggest that high dietary fructose might play a significant role in cancer metabolism and can exacerbate a number of aspects of metabolic syndrome. Addressing the role that fructose plays in human health is a controversial question and requires a detailed understanding of many factors including the mechanism of fructose transport into healthy and diseased cells. Fructose transport into cells is thought to be largely mediated by the passive hexose transporters Glut2 and Glut5. To date, no probes that can be selectively transported by one of these enzymes but not by the other have been identified. The data presented here indicate that, in MCF-7 cells, a 1-amino-2,5-anhydro-D-mannitol-based fluorescent NBDM probe is transported twice as efficiently as fructose and that this takes place with the aid of Glut5. Its Glut5 specificity and differential uptake in cancer cells and in normal cells suggest this NBDM probe as a potentially useful tool for cross-cell-line correlation of Glut5 transport activity.

Tunable GLUT–Hexose Binding and Transport via Modulation of Hexose C‐3 Hydrogen‐Bonding Capabilities

“…Although 4 showed no effect on GLUT5‐mediated transport of [ 14 C]‐ d ‐fructose (Figure ), it did inhibit [ 14 C]‐ d ‐glucose uptake into EMT‐6 cells (IC 50 =3.1±0.3 m m , Figure ). This represents the first example of an apparent target of a d ‐glucose‐specific transporter protein by a derivative of 2,5‐AM; compounds of this class have previously been shown to target d ‐fructose transporters such as GLUT5 . Inhibition of [ 14 C]‐ d ‐glucose transport by 3 and 5 was also examined.…”

“…Holman and co‐workers described C‐1‐modified 2,5‐AM derivatives as high affinity GLUT5 ligands . Based on Holman's work, McQuade and co‐workers recently reported a fluorescent 2,5‐AM‐based probe (1‐NB D ‐AM 9 , Figure A), which exhibited d ‐fructose‐dependent uptake into tumor cells . To develop tracers for molecular imaging, minimal efflux from target cells in culture should be observed.…”

“…Early structure–activity relationship studies demonstrated the necessity of secondary hydroxyl groups at the C‐3, C‐4 and C‐5 positions of d ‐fructose for GLUT5‐mediated transport . However, the hydroxyl group at C‐6 of d ‐fructose derivatives plays a negligible role in binding with GLUT5 (Figure ) . Consequently, GLUT5 targeting probes have been developed by the modification of the C‐6 position; however, these probes suffer from rapid efflux, presumably because of the absence of the C‐6 hydroxyl group, whose removal precludes metabolic trapping through phosphorylation by hexokinase …”

Flow synthesis of a versatile fructosamine mimic and quenching studies of a fructose transport probe

“…2) [17]. While we did not expect to observe significant self-quenching over this range, we measured the fluorescent intensity of NBDM from 1–40 μM (1X phosphate buffer solution).…”

“…Using design principles gleaned from the Holman group [13–15] as well as other fructose analogue research [16], we synthesized NBDM [17] and demonstrated that this probe is transported into cancer cells known to overexpress Glut5 and poorly transported into cells known to express little Glut5 [2,5,18]. We demonstrated that the transport is inhibited by fructose but not by other dietary sugars (glucose, glucosamine) [17]. Furthering our understanding of fluorescent probes like NBDM will expedite the development of Glut5-specific PET compounds which could be non-invasive tools for determining Glut5 expression in vivo and provide a means for monitoring the onset and progression of metabolic syndrome and aggressive cancers.…”