An investigation into the apoptotic inducing effect of fusaric acid on human lymphocytes and its role in cell growth inhibition.
Fusaric acid (FA) (5-butylpicolinic acid) is a divalent ion chelating agent that has low affinity for Ca2+ and Mg2+ and a high affinity for other essential metal ions such as Fe2+ Mn2+, Zn2+ and Cu2+. Its mode of action therefore may involve its interference with various transition metal ions and thus may be analogous to picolinic acid. Fusaric acid inhibits the proliferation of numerous cell lines in vitro. In the current in vitro study the effects of FA on peripheral blood lymphocytes was studied. Lymphocytes from a healthy volunteer were treated with varying concentrations of FA (3uM, 6uM, 25uM, 50uM 100uM 200uM, 400uM, and 1000uM) to assess the toxins apoptotic inducing potential. The 'Comet Assay' (Single cell gel electrophoresis), DNA fragmentation and Annexin V flous assays were employed to assess apoptosis. These assays proved that FA induces apoptosis in human lymphocytes. Lymphocytes were also incubated with phytohaemagglutinin (PHA) (10ug/ml) and increasing doses of FA (10, 50, 100 and 200uM). After 24, 48 and 72 hours of incubation an aliquot of the cells was stained with propidium iodide and subjected to flow cytometric analysis to assess the DNA configuration. Phytohaemagglutinin stimulation led to a significant increase of the S-phase of the cell cycle after 48 and 72 hours of incubation. All the PHA induced effects were reduced by co-incubation with increasing doses of FA. Lymphocytes were inhibited in the S-phase at 100 and 200uM concentration of FA. The current study shows that the in vitro inhibitory effects of FA can be demonstrated using flow cytometric technology on a cellular level. Fusaric acid leads to an inhibition of cell cycle progression in peripheral blood lymphocytes.