Objective Cytostatics are widely used to treat paediatric cancer with the intention to eliminate cancer cells by apoptosis. 5-Fluorouracil (5-FU) is frequently used in the treatment of malignancies. Previous studies with 5-FU and different cell lines indicate that the pro-apoptotic protein Bax and the tumour suppressor protein p53 are central actors in this process. The acute leukaemic T-cell line Jurkat E6 has mutations in both genes and 5-FU therefore needs to activate alternative death pathways. Previously, we have shown that incubation with 5-FU apparently triggers apoptosis in Jurkat cells in a dose-dependent manner, with a maximal response within 72 h; death response was attenuated in the presence of general caspase inhibitor.
Methods Jurkat T cells were treated with 5-FU for different time periods. Caspase-3 activity and changes in the mitochondrial membrane potential were measured by flow cytometry. Expression of various proteins, eg, PARP, NOXA and Mcl-1, was examined by Western blot.
Results Flow cytometric analysis showed activation of caspase-3 in a time and dose-dependent manner. Using Western blot we observed decreasing levels of anti-apoptotic and increasing levels of pro-apoptotic proteins. Treatment with 5-FU induced a breakdown of the mitochondrial membrane potential.
Conclusion Our results indicate that Jurkat T cells, previously thought to be resistant, can indeed be induced to undergo cell death, using sufficient doses of 5-FU and incubation time. The apoptotic pathway induced by 5-FU in this cell line may provide a rational basis for the design of chemotherapy.