Proapoptotic Effects of triazol-1,4-Naphthoquinones Involve Intracellular ROS Production and MAPK/ERK Pathway in Human Leukemia Cells

Abstract

Background: The natural products constitute an important source of antitumor and cytotoxic agents. Naphthoquinones are effectively quinones present in different plants, with demonstrated anticancer activities. A recent study conducted by our group demonstrated the antileukemic potential of two novel triazol-1,4- naphthoquinones derivatives, PTN (2-(4-Phenyl-1H-1,2,3-triazol-1-yl)-1,4-naphthoquinone) and MPTN (2-[4- (4-Methoxyphenyl)-1H-1,2,3-triazol-1-yl]-1,4-naphthoquinone). Although, the mechanisms underlying the proapoptotic effects of PTN and MPTN have not been fully elucidated so far.

Objective: The aim of this study was to evaluate the proapoptotic mechanism of PTN and MPTN in human acute leukemia cells.

Methods: We used fluorescence microscopy to observe acridine orange and annexin V staining cells. Flow cytometry assay has also been used for ROS quantification, BAX and cytochrome c proteins expression and apoptosis analysis. MTT assay and western blotting technique have been performed as well for MAPK pathway analysis.

Results: By using the acridine orange and annexin V staining with fluorescence microscopy, we have characterized the proapoptotic effects of PTN and MPTN in HL-60 cells involving the intrinsic mitochondrial pathway, since these compounds promoted an increase in the intracellular BAX and cytochrome c protein levels (p<0.05). We further demonstrated that apoptosis induction in HL-60 cells was mediated by increasing intracellular ROS levels via ERK but not p38 MAPKs pathway.

Conclusion: Taken together, these results have demonstrated that PTN and MPTN are promising tools for the development of new anti-leukemic drugs.

Keywords: Cancer; HL-60; acute leukemia; cytotoxicity; naphthoquinone; reactive oxygen species.