On the basis of our finding that the antitumor effect of 5-{4-[(1-methylcyclohexyl)methoxy]benzyl}thiazolidine-2,4-dione, a thiazolidinedione peroxisome proliferator-activated receptor (PPAR)γ agonist, was, in part, attributable to its ability to block glucose uptake independently of PPARγ, we used its PPARγ-inactive analogue to develop a novel class of glucose transporter (GLUT) inhibitors. This lead optimization led to compound 30 {5-(4-hydroxy-3-trifluoromethylbenzylidene)-3-[4,4,4-trifluoro-2-methyl-2-(2,2,2-trifluoroethyl)butyl]thiazolidine-2,4-dione} as the optimal agent, which exhibited high antitumor potency through the suppression of glucose uptake (IC(50), 2.5 μM), while not cytotoxic to prostate and mammary epithelial cells. This glucose uptake inhibition was associated with the inhibition of GLUT1 (IC(50), 2 μM). Moreover, the mechanism of antitumor action of compound 30 was validated by its effect on a series of energy restriction-associated cellular responses. Homology modeling analysis suggests that the inhibitory effect of compound 30 on glucose entry was attributable to its ability to bind to the GLUT1 channel at a site distinct from that of glucose.