Apoptosis induction in human leukemia cells by novel 2-amino-5-benzylthiazole derivatives

Derivatives of 2-amino-5-benzylthiazole are heterocyclic pharmacophores that exhibit different pharmacological activities including anticancer action. The mechanisms of such action of these compounds are not clear. The aim of the present study was to investigate apoptosis induction, particularly DNA damage in human leukemia cells, by the novel synthesized thiazole derivatives ‒ 2,8-dimethyl-7-(3-trifluoromethyl-benzyl)pyrazolo[4,3-e]thiazolo[3,2-a]pyrimidin-4(2H)-one (compound 1) and 7-benzyl-8-methyl-2-propylpyrazolo[4,3-e]thiazolo[3,2-a]pyrimidin-4(2H)-one (compound 2). Western-blot analysis, DNA comet assay in alkaline conditions, diphenylamine DNA fragmentation assay, agarose gel retardation, and methyl green DNA intercalation assays were used to study the effects of the studied compounds in human leukemia cells. These compounds induced PARP1 and caspase 3 cleavage in the leukemia cells, also increased the level of pro-apoptotic Bim protein and the mitochondrion-specific EndoG nuclease, and decreased the level of the anti-apoptotic Bcl-2 protein. They caused DNA single-strand breaks and DNA fragmentation in the leukemia cells without direct DNA binding or DNA intercalation. Thus, novel 2-amino-5-benzylthiazole derivatives may be promising agents for apoptosis induction in the targeted human leukemia cells.