Abstract

OBJECTIVES
Apotosis induced by metals and metal-related deleterious conditions has only recently been studied. Although the toxic effects of heavy metal are well described, little is known about the mechanism of apoptosis by heavy metal toxicity. This study is designed to define the induction of apoptosis by which heavy metals exert the cytotoxic effect on human promyelocytic leukemic HL-60 cells.
Methods
After the incubation with CdC12, Na2SeO3 and HgC12, viability of the cells were measured by MTT assay. DNA fragmentation was analyzed by electrophoresis. For measurement of caspase 1 and 3-like proteases activity, the whole lysates were subjected to the proteolytic cleavage and then measured by using fluorospectrometry. c-JUN N-terminal kinase (JNK) activity was detected by an in vitro kinase assay. Transcriptional activities of activating protein-1 (AP-1) and nuclear factor-kB (NF-kB) were measured by elec trophoresis mobility shift assay (EMSA).
RESULTS
Cadmium (l2OuiN/I) and selenium (30,iM) induce the apoptosis of HL-60 cells which is characterized by the ladder pattern of DNA fragmentation. Cadmium and selenium induce the activation of caspase-3 in a time dependent manner. They also increase the phosphotransferase activities of c-JUN N-terminal kinase (JNK) in cadmium and selenium treated HL-60 cells. Furthermore, cadmium and selenium increase the activation of transcriptional factors including AP-i and NF-kB.
CONCLUSIONS
These results suggest that cadmium and selenium induce the apoptotic death of HL-60 cells via activation of DEVD-specific caspase, JNK and transcriptional factors such as AP-1 and NF-kB.

• Keywords: Apoptosis;Cadmium;Selenium;Caspase;JNK;AP-1;NF-kB