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Abstract
Background/Aims
Ligands for peroxisome proliferator-activated receptorγ (PPARγ), a member of the ligand-acti-vated nuclear receptor superfamily, exhibit anti-tumoral effects and are associated with de novo synthesis of proteins involved in regulating the cell cycle and cell survival/death. Helicobacter pylori (H. pylori) is an etiologic agent for gastric adenocarcinoma, and raises the cell turnover of gastric epithelium. The aim of this study was to investigate the effect of PPARγ ligand rosiglitazone on the cell proliferation and the expressions of p27 and Skp2 protein in H. pylori infected gastric epithelial cells.
Methods
We examined the expression of PPARγ by Western blot in H. pylori infected AGS human gastric epithelial cells. The effect of rosiglitazone on the survival of H. pylori infected AGS cells was assessed by cell viability assay. After the treatment of rosiglitazone in H. pylori infected AGS cells, the expressions of p27 and Skp2 were assessed by Western blot.
Results
The expression of PPARγ protein was increased in H. pylori infected AGS cells. Cell growth was inhibited and decreased in dose- and time- dependent manner in H. pylori infected AGS cells treated with rosiglitazone. A decrease in Skp2 expression and a reciprocal increase in p27 expression were found in dose- and time-dependent manner in H. pylori infected AGS cells treated with rosiglitazone.
Conclusions
Rosiglitazone inhibited the growth of H. pylori infected AGS cells. Rosiglitazone attenuated Skp2 expression, thereby promoting p27 accumulation in H. pylori infected human gastric epithelial cells. Further studies will be needed to find the effects of accumulation on cell turnover in H. pylori infection and the role in the H. pylori-associated gastric carcinogenesis.
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Fig. 1.
PPARγ protein expression in H. pylori non-infected and infected AGS cells. Western blot analyses were performed using anti-PPARγ monoclonal antibody. The PPARγ protein and β- actin as control expression was detected in H. pylori non-infected and infected AGS cells. H. pylori infection increased PPARγ protein expression.
Fig. 2.
Effects of rosiglitazone on H. pylori infected AGS cell proliferation. Cell proliferation was determined using the WST-1 assay. Rosiglitazone inhibited cell proliferation in H. pylori infected AGS cells in a dose- and time-dependent manner (∗p ＜0.01, when compared to vehicle only).
Fig. 3.
(A) p27 and Skp2 expression in non-treated AGS cells. Western blot analyses were performed using anti-p27 monoclonal antibody and anti-Skp2 polyclonal antibody. By densitometric analysis, the p27 protein and Skp2 protein expression was detected at several time points after normalization for β-actin. (B) p27 and Skp2 expression in H. pylori infected AGS cells by rosiglitazone. The p27 protein, Skp2 protein and β-actin as control expression was detected in H. pylori infected AGS cell at several time points after treatment with 100μ M rosiglitaone for 48 h. Rosiglitazone decreased Skp2 expression and increased p27 expression in H. pylori infected AGS cells in time-dependent manner.
Fig. 4.
p27 (A) and Skp2 (B) expression in H. pylori infected AGS cells by rosiglitazone. The expression levels of p27 protein and Skp2 protein were shown as densitometric values for the ratio of p27/β-actin and Skp2/β-actin, respectively. After 48 h, rosiglitazone † p decreased Skp2 expression and increased p27 expression in H. pylori infected AGS cells in dose-dependent manner. (∗p＜0.01, ＜0.001, respectively, compared to the control).
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