Effects of magnesium sulfate on apoptosis in cultured human gastric epithelial cells

This study investigated the effect of magnesium sulfate (MgSO4) on the viability of the human gastric adenocarcinoma (AGS) epithelial cell line. AGS cells were exposed to various concentrations of MgSO4 for different time-periods and the effects on cell viability, DNA fragmentation, apoptotic gene expression, and caspase activity were investigated. A range of tests were employed in this study, including a lactate dehydrogenase cell viability assay, annexin V staining, reverse transcription polymerase chain reaction (RT-PCR), terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and several caspase activity assays. Expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), Fas ligand (FasL) and Fas receptor (FasR) were analyzed using RT-PCR. These analyses revealed that MgSO4 induced a dose-dependent reduction in AGS cell viability. Annexin V staining did not differ between negative control and treated cells, indicating that no apoptotic cells were detected. The TUNEL assay data were consistent with the annexin V staining results. FasL mRNA expression was increased and FasR mRNA expression was decreased in a dose-dependent manner by MgSO4. MgSO4 treatment tended to cause an initial (1 h) dose-dependent increase in the activities of caspase-3, -6, -8, and -9; however, these activities were subsequently inhibited (24 h). We deduced that MgSO4 exerted an anti-apoptotic effect in AGS cells via caspase activation.