Abstract
AIM: To explore the relationship between STAT1 and p53 mRNA expression in human gastric cancer cell line SGC7901 and to characterize the regulatory effect of interferon-γ (IFN-γ) on p53 expression in gastric cancer.
METHODS: After SGC7901 cells were treated with IFN-γ and antisense oligonucleotides (ASON) targeting the STAT1 gene, alone or in combination, the mRNA expression of p53 and STAT1 was tested by RT-PCR, and cell apoptosis was examined by Hoechst 33258 staining. The protein expression of p53 and STAT1 in human gastric cancer tissue was examined by immunohistochemistry. Average optical density was compared between different groups using Student's t test analysis. The relationship between the expression of STAT1 and P53 protein in human gastric cancer was evaluated using Spearman rank correlation analysis.
RESULTS: Treatment with IFN-γ up-regulated the mRNA expression of STAT1 and p53 in SGC7901 cells (both P < 0.05). Treatment with STAT1-specific ASON induced down-regulation of STAT1 mRNA expression (P < 0.05) in a concentration-dependent manner. The expression of p53 mRNA was lower in all ASON groups than in the control group (all P > 0.05). Simultaneous treatment with IFN-γ and STAT1-specific ASON induced lower STAT1 mRNA expression than treatment with IFN-γ alone (P < 0.05). The mRNA expression of p53 was higher in all cells treated simultaneously with IFN-γ and STAT1-specific ASON than in those treated with IFN-γ alone (all P > 0.05). There was no correlation between STAT1 and p53 mRNA and protein expression in human gastric cancer tissue and cell lines. Treatment with either IFN-γ or STAT1-specific ASON had no significant impact on cell apoptosis.
CONCLUSION: IFN-γ could regulate p53 expression in gastric cancer through a STAT1-independent pathway.
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