Structure-guided screening identifies Tucatinib as dual inhibitor for MCT1/2.

Cell surface glycoproteins Basigin or embigin form heterodimers with monocarboxylate transporters (MCTs), enhancing their membrane trafficking and modulating their transport functions. Cancer cells often reprogram their metabolism and depend on proton-coupled lactate transport mediated by MCTs to sustain their glycolytic state and to maintain intracellular pH. A deeper understanding of MCTs regulation may open avenues for the development of novel inhibitors, potentially applicable in clinical settings. Here, we determine the cryo-EM structures of the human MCT2-embigin complex in both apo and AR-C155858-bound states and observe that embigin engages in extensive interactions with MCT2, facilitating its localization to the plasma membrane and substrate transport. Given the high structural conservation among MCTs, we conduct virtual screening based on MCT1/2 structures and identify Tucatinib as an effective inhibitor of pyruvate transport mediated by both MCT1 and MCT2. We show that Tucatinib potently inhibits the proliferation and migration of cervical tumor cells in vitro and tumor growth in a mouse xenograft model, while exhibiting excellent biological safety. These findings offer molecular insights into the structural and functional mechanism of MCT2 and identify Tucatinib as novel dual inhibitor of both transporters.