Effects of inorganic and organic arsenic compounds on growth and apoptosis of human T-lymphoblastoid leukemia cells.

Background/aim: To investigate the effects of inorganic and organic arsenic compounds on human T-lymphoblastoid leukemia cells.

Materials And Methods: Cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5¬diphenyltetrazolium bromide (MTT) assay. Apoptotic cell morphology was examined by cell staining with Hoechst 33342. Cellular caspase-3/7 activities were measured after arsenic treatment.

Results: The inhibitory concentration by 50% (IC(50)) values of As(2)O(3) towards MOLT-4 and daunorubicin- resistant MOLT-4/DNR cell proliferation were 0.87 and 0.92 μM, while the values for arsenic acid were 69.1 and 116.6 μM, respectively. These arsenic compounds also inhibited mitogen-induced proliferation of human peripheral blood mononuclear cells. Six organic arsenic compounds did not inhibit leukemia cell proliferation. As(2)O(3) and arsenic acid induced apoptotic cell morphology and increased caspase-3/7 activity in the leukemia cells. Ascorbic acid and buthionine sulfoxide enhanced, while N-acetyl-L-cysteine abated, the suppressive effects of inorganic arsenic compounds on leukemia cell proliferation.

Conclusion: As(2)O(3) and arsenic acid inhibit proliferation and induce apoptosis in MOLT-4 and daunorubicine-resistant MOLT-4/DNR cells via glutathione-depletion and subsequent caspase-3/7 activation. Organic arsenic compounds have no inhibitory activity on the leukemia cell proliferation. Inorganic arsenic compounds are suggested as useful agents for treatment of T-lymphoblastoid leukemia.