CHEMBL5732730

Lactate Transport in MCT4-Expressing MDA-MB-453 Breast Cancer Cells: MCT4 may be stably expressed in MDA-MB-453 breast cancer cells that do not express native MCT1 or MCT4. MCT4 activity may be assessed by monitoring the intracellular pH change that accompanies lactate/proton symport, using the pH-sensitive fluorescent dye 2′,7′-bis-(carboxyethyl)-5(6)-carboxyfluorescein (BCECF), in a manner similar to that previously reported for MCT1 and MCT4. The following is an exemplary procedure for assaying MCT4 activity of the compounds of Formula (I). 2.5 μL BCECF-loaded cells, along with either 10 μL DMSO or 100×compound in DMSO, are added to 937.5 μL of Tyrode's Solution in a quartz 1.0 mL cuvette (PerkinElmer, B0631116). Fluorescence measurements are performed on a PerkinElmer LS55 fluorescence spectrometer with dual excitation wavelengths achieved using a filter wheel (FL Winlab program: Fast Filter; Excitation 490/440; Emission 535). After establishing baseline BCECF fluorescence (around 10-20 s), 50 μL of 1 M sodium L-lactate (Sigma-Aldrich) is added to the cuvette (final concentration: 50 mM) and rapidly mixed. The time-dependent decrease in BCECF fluorescence (490/440 ratio) may be fit to an exponential decay curve (Prism GraphPad) to determine the rate of lactate transport.