Abstract 6777: Characterization of the dual MCT1 and MCT4 inhibitor MCT-IN-1 in MOC1 cell line demonstrates increased apoptosis and compensatory upregulation of glutathione conjugation gene sets

Abstract Background: Head and neck squamous cell carcinoma, like many solid tumors, upregulates glycolysis regardless of O2 availability via the Warburg effect, which results in accumulation of intracellular lactate. To avoid apoptosis from the resultant decreased pH, these cells export lactate via monocarboxylate transporters (MCT), primarily MCT1 and MCT4, with overexpression of MCT1 and MCT4 having been linked to poor prognosis. Methods: Mouse Oral Cancer (MOC1) cells were treated with MCT-IN-1, a dual MCT1 and MCT4 inhibitor. Flow cytometry was utilized to characterize apoptosis and S-phase of the cell cycle. Bulk RNAseq data were obtained from both MCT-IN-1-treated and untreated MOC1 cells and analyzed with unbiased gene set enrichment analysis (GSEA). Leading edges of enrichment were analyzed by using the STRING database of protein-protein interactions. Results: Treatment of MOC1 cells with MCT-IN-1 resulted in decreased tumor cell count (p<0.01), increased apoptosis (p<0.01), and reduced S-phase of the cell cycle (p<0.01) compared to untreated cells. Unbiased GSEA of bulk RNAseq data, contrasting MCT-IN-1 treated versus untreated cells, revealed upregulation of endoplasmic reticulum (ER) stress (NES 1.79, FDR=0.012), suggesting possible mechanism of cell death. In addition, the glutathione conjugation gene set was found to be upregulated (NES 1.75, FDR=0.016), suggesting a possible compensatory response mechanism. Further, GSEA revealed significant enrichment of the oxidative stress and redox pathway (NES 1.74, FDR=0.016), including glutathione transferase and oxidoreductase activities. STRING analysis of upregulations in gene expression revealed a dense protein-protein interaction network, suggesting coordinated roles in detoxification (FDR = 1.00e-16) and cellular stress response mechanisms (FDR = 2.61e-41) in MOC1 cells treated with MCT-IN-1. Conclusions: We report the first characterization of the dual MCT1 and MCT4 inhibitor MCT-IN-1. Treatment of MOC1 cells in vitro with MCT-IN-1 induces tumor cell apoptosis possibly via upregulation of ER stress and further demonstrates upregulation of glutathione conjugation gene sets, suggesting a possible compensatory mechanism. Validation with in vivo studies and further evaluation of the exact mechanism of these findings are required. Citation Format: Eric V. Mastrolonardo, Víctor Díaz Barros, Zhao Lin, Hani Samarah, Julian Jackson, Adam J. Luginbuhl, Alban Linnenbach, Ubaldo Martinez-Outschoorn, Joseph M. Curry. Characterization of the dual MCT1 and MCT4 inhibitor MCT-IN-1 in MOC1 cell line demonstrates increased apoptosis and compensatory upregulation of glutathione conjugation gene sets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6777.