In the current study, we have used a similar assay to identify chemicals that increase iron uptake into cells and demonstrate that these chemicals are effective in increasing iron transport across Caco2 cells, a model system for studying intestinal iron absorption, and increasing iron uptake into various cancer cell lines, favourably altering several aspects of the malignant phenotype. ubiquitin-Proteasome system Methods

Cell lines and Chemicals All antibodies were purchased from Santa Cruz Biotechnology, Inc. (Santa Cruz, CA) except for rabbit anti-HIF-1α and -2α which were purchased from Novos Biologicals (Littleton, CO). All analytical chemicals were from Sigma-Aldrich (St. Louis, MO). The chemical libraries were obtained from ChemDiv (San Diego, CA) and TimTec (Newark, DE). CM-H2DCFDA (5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate, acetyl ester) or DCFDA and calcein-AM were from Invitrogen (Carlsbad, CA). The cell lines K562, ITF2357 solubility dmso PC-3, Caco2, MDA-MB231, and 267B1 were

obtained from ATCC (Bethesda, MD). RPMI1640 and DMEM culture media and fetal calf serum (FCS) were obtained from Atlanta Biologicals (Lawrenceville, GA). Screening for chemicals that increase iron uptake K562 cells were loaded with calcein by incubating cells with 0.1 μM of Calcein-AM for 10 min in 0.15 M NaCl-20 mM Hepes buffer, pH 7.4, with 0.1% BSA at 37°C followed by extensive washing with NaCl-Hepes buffer to remove extracellular bound calcein, and aliquoted at 5 × 104 – 1 × 105 cells/well in 96-well plates containing test compounds at 10 μM and incubated for 30 min in a humidified 37°C incubator with 5% CO2 before baseline fluorescence was obtained at 485/520 nm (excitation/emission) with 0.1% DMSO as the vehicle control and DTPA as a strong iron chelator control to block all iron uptake. much The fluorescence was then obtained 30 min after addition of 10 μM ferrous ammonium sulfate in 500 μM ascorbic acid (AA). The percentage of fluorescence quench was calculated relative

to 200 μM DTPA added as a blocking control and DMSO as a vehicle control as follows: (1) where Δ F is the change in fluorescence, or fluorescence quench, observed in any well, F0 represents the fluorescence after 30 min of compound, and Ff represents the fluorescence 30 min after addition of Fe. These results were normalized to the blocking and vehicle controls as follows: (2) where Δ Fn is the normalized quench observed after addition of iron, Fcompound is the Δ F observed with compound, Fmin is the average Δ F of the DMSO control; and Fmax is the average Δ F of the DTPA control. With this normalization 100% indicates that a test compound is as potent as DTPA in blocking iron-induced quenching and 0% indicates no inhibition of iron quenching by a test compound or the same quench as observed with the DMSO vehicle control. Compounds with Δ Fn between 0% and 100% are defined as inhibitors of iron uptake.