Glyceryl Trinitrate Enhances Caffeine Cytotoxicity Under Metabolic Stress in Cancer Cells.

抄録

Cancer cell metabolism represents a critical therapeutic target, particularly under conditions of metabolic stress induced by glycolysis inhibition. Nitroglycerin (glyceryl trinitrate, GTN), a nitric oxide donor, and 2-deoxy-D-glucose (2-DG), a glycolysis inhibitor, have individually demonstrated anticancer potential through modulation of cellular metabolism and redox balance. In this study, we investigated the cytotoxic and combined effects of GTN and caffeine under 2-DG-induced metabolic stress in human cancer cell lines (HeLa, A549, HT29, and MRC-5). Cell viability was assessed using the sulforhodamine B assay after 24 and 48 h treatments, while drug interactions were evaluated using the Chou-Talalay method and combination index (CI) values. 2-DG alone reduced cell viability in a concentration- and time-dependent manner, with IC₅₀ values ranging from 2.01 to 7.05 mM depending on the cell line and exposure period. The combined treatment further enhanced cytotoxicity, particularly in A549 cells, where viability decreased to approximately 63% after 48 h and the calculated IC₅₀ value for GTN in the presence of caffeine reached 0.143 μM. CI analysis demonstrated synergistic interactions in HeLa and A549 cells (CI < 1), whereas HT29 cells predominantly exhibited antagonistic responses (CI > 1). However, strong synergistic effects were also observed in MRC-5 fibroblasts, indicating limited selectivity toward cancer cells. Molecular docking suggested favorable in silico binding of GTN to aldehyde dehydrogenase 2 (ALDH2) and caffeine to the adenosine A2A receptor. Nevertheless, these findings should be considered exploratory and hypothesis-generating because target expression, enzymatic activity, and pathway activation were not experimentally validated. Overall, the results suggest that GTN enhances caffeine-induced cytotoxicity under metabolically stressed conditions through combined metabolic and redox perturbation, although the magnitude of the response depends on cellular context and warrants further mechanistic investigation.