Comparative analysis of apoptosis induction by selenium compounds in human lymphoblastic leukemia MT-4 cells.
OBJECTIVE
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 microM, while sodium selenate was much less toxic inducing apoptotic cell death only at 300 microM. 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.


CONCLUSIONS
Sodium selenite induced apoptosis is accompanied by increased Bax expression.
Philchenkov
A
A
RE Kavetsky Institute of Experimental Oncology, Pathology and Radiobiology, National Academy of Sciences of Ukraine, Kyiv 03022, Ukraine. a_philch@onconet.kiev.ua
Zavelevich
M
M
Khranovskaya
N
N
Surai
P
P
D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D020552:Comet Assay; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000473:pathology*; D018036:Selenium Compounds / Q000008:administration & dosage*; D051028:bcl-2-Associated X Protein / Q000187:drug effects* / Q000378:metabolism
D018036:Selenium Compounds; D051028:bcl-2-Associated X Protein