Comparative analysis of apoptosis induction by selenium compounds in humanlymphoblastic leukemia MT-4 cells

Philchenkov A., Zavelevich M., Khranovskaya N., Surai P.

Summary. Aim: The precise mechanisms of apoptosis induced by various selenium compounds are not well understood. Therefore, the apoptogenic activity of two inorganic selenium compounds, sodium selenite and sodium selenate, in human T-cell acute lymphoblastic leukemia MT-4 cells was compared focusing on their effects on cell cycle progression and activation of proapoptotic Bax protein. Methods: Apoptosis and cell cycle distribution of MT-4 cells exposed to inorganic selenium compounds was assessed by flow cytometry upon propidium iodide staining. Bax expression was analyzed by flow cytometry of cells labeled with anti-Bax monoclonals. Extent of DNA damage was assessed by Comet analysis. Results: Sodium selenite induced apoptosis in dose-dependent mode starting from concentrations of 10 µM, while sodium selenate was much less toxic inducing apoptotic cell death only at 300 µM. Sodium selenite but not sodium selenate caused a slight arrest in G2/M phase of cell cycle. The cytotoxicity of sodium selenite was accompanied by DNA damaging effects visualized in DNA comet assay. Nevertheless, the drastic increase in Bax flow cytometry intensity was evident only in selenite-induced apoptosis. Conclusion: Sodium selenite induced apoptosis is accompanied by increased Bax expression.

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