Differential response of gastric carcinoma MKN-45 and 23132/87 cells to H2O2 exposure

Background/aims: Reactive oxygen species are involved in tumor progression but how they function is not well understood. In this study, we investigated and compared the effects of hydrogen peroxide on the survival, apoptosis, accumulation of oxidative stress, and matrix metalloprotein-7 gene expression on human gastric carcinoma MKN-45 and 23132187 cells. Methods: The cell lines were exposed to hydrogen peroxide in a dose-and time-dependent manner. The surviving cells were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The oxidative stress was analyzed by an oxidative stress marker, 2,7-dichlorofluorescein diacetate, under fluorescence microscope. The effect of oxidative stress on the apoptotic behavior, caspase-3 activity, and matrix metalloprotein-7 gene expressions of the cell lines were determined, respectively, by TUNEL, caspase-3 activity assay, and quantitative real-time polymerase chain reaction. Results: Exposure of the gastric cancer cells to oxidative stress resulted in dose-and time-dependent decrease in the survival of the cell lines. While MKN-45 cells had oxidative stress, increased apoptosis with no caspase-3 activity, and increased matrix metalloprotein-7 expression following hydrogen peroxide exposure, 23132187 cells showed none, with internal oxidative stress accumulation prior to hydrogen peroxide exposure. Conclusions: The two gastric cancer cell lines responded differently to oxidative stress conditions, and unlike in 23132187 cells, matrix metalloprotein-7 gene expression was shown to be affected by external hydrogen peroxide in MKN-45 cells.