Atorvastatin Exerts More Selective Inhibitory Effects on hMCT2 than on hMCT1 and hMCT4

Abstract

Background/Aim: Human monocarboxylate transporter 1 (hMCT1), hMCT2, and hMCT4 transport monocarboxylates, such as L-lactate and pyruvate, with pH dependency. They are often over-expressed in various cancer cells and mediate the energy balance and pH homeostasis. Therefore, hMCT inhibitors can potentially be used as anticancer drugs. However, isoform-selective inhibitors have not yet been well-characterized. In addition, several statins and 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors have been reported to inhibit hMCTs, but their selectivity has not yet been evaluated. In this study, we aimed to determine whether statins could inhibit hMCT1, hMCT2, and hMCT4. Materials and Methods: We expressed hMCT1, hMCT2, and hMCT4 in a heterologous expression system of Xenopus oocytes and performed inhibitory experiments with various statins (fluvastatin, atorvastatin, simvastatin, rosuvastatin, pravastatin, and pitavastatin). As the three-dimensional structure of hMCT2 has been recently reported, docking simulations of statins and their structures were also performed to estimate the inhibition site. Results: All statins inhibited the transport activities of hMCT1, hMCT2, and hMCT4. In addition, atorvastatin was found to be a potent isoform-selective inhibitor of hMCT2. Docking simulation indicated that atorvastatin could interact with a site surrounded by transmembrane (TM)-2, TM11, and intracellular helix in the TM6/7loop. Therefore, targeting this site may lead to the discovery of more potent hMCT2-selective inhibitors. Conclusion: Atorvastatin exerts selective inhibitory effects on hMCT2. These findings provide insights into the inhibitory mechanism of statins against hMCT1, hMCT2, and hMCT4 and may aid in the development of novel anticancer agents.