Glyceryl Trinitrate Enhances Caffeine Cytotoxicity Under Metabolic Stress in Cancer Cells

Area of Science:

• Biochemistry
• Pharmacology
• Oncology

Background:

• Cancer cell metabolism is a key therapeutic target, especially under metabolic stress.
• Glycolysis inhibitors like 2-deoxy-D-glucose (2-DG) and nitric oxide donors like nitroglycerin (GTN) have shown anticancer potential.
• Investigating drug combinations under metabolic stress can reveal novel therapeutic strategies.

Purpose of the Study:

• To evaluate the combined cytotoxic effects of nitroglycerin (GTN) and caffeine on human cancer cell lines under 2-DG-induced metabolic stress.
• To determine the drug interaction patterns (synergistic, additive, or antagonistic) of GTN and caffeine in combination with 2-DG.
• To explore potential molecular targets using in silico methods.

Main Methods:

• Human cancer cell lines (HeLa, A549, HT29) and fibroblasts (MRC-5) were treated with 2-DG, GTN, and caffeine.
• Cell viability was assessed using the sulforhodamine B assay at 24 and 48 hours.
• Drug interactions were quantified using the Chou-Talalay method to calculate combination index (CI) values.
• Molecular docking was performed to predict binding interactions of GTN and caffeine with potential targets.

Main Results:

• 2-DG alone reduced cell viability in a dose- and time-dependent manner across cell lines.
• Combined treatment with GTN and caffeine under 2-DG stress enhanced cytotoxicity, particularly in A549 cells.
• Synergistic interactions (CI < 1) were observed in HeLa and A549 cells, while HT29 cells showed predominantly antagonistic responses (CI > 1).
• Strong synergistic effects were also noted in MRC-5 fibroblasts, indicating a lack of cancer cell selectivity.
• Molecular docking suggested favorable binding of GTN to ALDH2 and caffeine to the adenosine A2A receptor.

Conclusions:

• GTN enhances caffeine-induced cytotoxicity under 2-DG-induced metabolic stress via combined metabolic and redox perturbation.
• The effectiveness and selectivity of the GTN-caffeine combination are context-dependent and require further mechanistic validation.
• Findings suggest potential for combination therapies but highlight the need for experimental validation of molecular targets and pathway activation.