The study of the apoptogenic effect of pyrimidine derivatives on murine leukemia cells

Abstract

BACKGROUND: In the light of the recent findings concerning the role of apoptosis and of tumor cell enzymes in cancer chemotherapy, the interest in pyrimidine derivatives has greatly increased. Thio- and hydrazine- pyrimidines were synthesized as potential antimetabolites inhibiting the biosynthesis of nucleic acids. Some of them demonstrated biological activity, including antibacterial and antitumor action. The aim of this study was to analyze the cytotoxic activity and the ability of some derivatives to induce apoptosis in murine leukemia cells. METHODS: Exponentially growing cells were incubated with compounds and after 24, 48, and 72 hours were stained with trypan blue and counted hemocytometrically. For detection of the cell fraction undergoing apoptosis, a morphological analysis was made using fluorescent dye propidium iodide. RESULTS: Eight thio- and hydrazine- pyrimidine derivatives were investigated. 2-Thiouracil and 6- hydrazinouracil did not influence the cell growth. 2,4-dithiouracil, 2-thio-4-hydrazinouracil, 2-hydrazinouracil, and 2-thio-5-fluorouracil decreased cell proliferation, but even at the highest studied concentration (1000 ?M) had no cytostatic action. Only high concentrations of 2,4-dihydrazinouracil and 2- chloro-4-hydrazinouracil showed a strong cytotoxic activity. The treatment with 2,4-dihydrazinouracil as well as with 5-fluorouracil caused the appearance of apoptotic cells with typical fragmented condensed nuclei, ghosts and apoptotic bodies. In contrast, dead cells treated with 2-chloro-4-hydrazinouracil did not show apoptotic morphology. CONCLUSION: Among studied eight thio- and hydrazine- pyrimidine derivatives only 2,4-dihydrazinouracil demonstrated strong apoptogenic activity. Its active concentrations were about 100 times higher than apoptogenic concentrations of 5-fluorouracil which points to different mechanisms of cytotoxic action.