Abstrakt
Zinc is an important cellular antioxidant. We investigated its role in chromium-induced oxidative stress and apoptosis in human tumor cell line Hep-2.
The measured parameters included intracellular labile zinc content (Zinquin-E fluorescence), cell viability (WST-1 assay), oxidative stress (spectrophotometry), mitochondrial potential (flow cytometry), caspase-3 activity, and PARP cleavage (immunofluoroscence). We found that Hep-2 cells contain abundant labile zinc stores that may be depleted by the ionophore TPEN or increased by external zinc supplementation.
Chromium (VI)-induced cytotoxicity and apoptosis were enhanced in zinc-depleted cells after 24 h, in particular at chromium (VI) concentrations of 50 umol/l. On the other hand, elevated levels of labile zinc were able to protect against apoptosis induced by 10 umol/l chromium (VI) but at higher chromium (VI) concentrations (50 and 150 umol/l) acted synergistically, significantly enhancing oxidative stress and the course of apoptosis.