Cadmium-induced cell killing in Sacharomyces cerevisiae involves increases in intracellular NO levels

Cadmium is a widespread environmental pollutant and poses some potential risks to human health. However, the signaling events controlling cadmium toxicity are not fully understood. In this study, we examined the effect of cadmium chloride on cell viability and the intracellular nitric oxide (NO) level in yeast cells. The results showed that exposure of yeast cells to cadmium (0-100 μM) could induce cell killing with significantly increased intracellular NO levels. Morphological analysis of the nuclei with 4('),6-diamidino-2-phenylindole staining and DNA strand breaks analysis showed that cadmium at 50 μM can induce cell apoptosis in yeast cells. Treatment of yeast cells with cadmium (50 μM) and the nitric oxide scavenger c-PTIO [2-(4-carboxyphenyl)-4,4,5,5-teramethylimidazoline-1-oxyl-3-oxide; 0.2 mM] showed that c-PTIO attenuated the cadmium-induced cell killing. Our findings indicated that cadmium-induced yeast cell killing is mediated by a directly increased intracellular NO level.