Biochemical and cell cycle perturbations in methotrexate-treated cells

Area of Science:

• Biochemistry
• Cell Biology
• Pharmacology

Background:

• Methotrexate (MTX) is a chemotherapy agent.
• Understanding MTX's mechanism in leukemia is crucial.
• Deoxyribonucleoside triphosphate (dNTP) pools are vital for DNA synthesis.

Purpose of the Study:

• To investigate the impact of exogenous thymidine (dThd) and hypoxanthine (Hx) on MTX's effects.
• To analyze MTX's influence on cell cycle kinetics and dNTP pools.
• To correlate dNTP alterations with MTX cytotoxicity.

Main Methods:

• Cultured human leukemic T-cells (CCRF-CEM) were treated with MTX.
• Exogenous dThd and Hx were added in varying concentrations.
• Cell cycle kinetics, DNA synthesis rates, and dNTP pools were measured.

Main Results:

• MTX cytotoxicity increased with dose up to 10(-7) M, then plateaued.
• MTX inhibited DNA synthesis and altered dTTP and dGTP pools.
• dThd reduced MTX cytotoxicity; Hx had variable effects, potentiating toxicity at higher MTX concentrations.
• Reduced MTX toxicity correlated with increased dTTP and dGTP levels and DNA synthesis rates.

Conclusions:

• MTX cytotoxicity is closely linked to dNTP pool alterations and DNA synthesis inhibition.
• Exogenous purines like dThd and Hx can modulate MTX's efficacy and toxicity.
• These findings offer insights into potential strategies for optimizing MTX-based cancer therapy.