Role of IFN-γ-STAT1 pathway in human gastric adenocarcinoma

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AIM: To investigate relationships among STAT1, Caspase-7 and p21 in gastric adenocarcinoma tissue and gastric adenocarcinoma cell SGC7901, and to shed light on features of IFN-γ-STAT1 pathway in gastric adenocarcinoma. METHODS: Gastric adenocarcinoma tissue was tested by immunohistochemical method. SGC7901 cell was treated with IFN-γ and STAT1 antisense oligonucleotides, and mRNA and protein expression was detected using RT-PCR, immunocytochemistry and image analysis methods. Apoptosis was determined by Hoechest 33258. RESULTS: Caspase-7 was positive correlation with STAT1 and p21 (r = 0.32, 0.22, both P < 0.05) in gastric adenocarcinoma tissue. IFN-γ promoted mRNA and protein expression of STAT1, Caspase-7 and p21 was up-regulated in SGC7901 cell (P < 0.05). After treatment with IFN-γ along with varied concentrations of STAT1 antisense oligonucleotides, significantly lower STAT1 mRNA and protein expression was observed than IFN-γ used alone in SGC7901 cells, which showed a concentration-dependent manner (P < 0.05); significantly lower Caspase-7 and P21 protein expression was observed than IFN-γ used alone in SGC7901 cell in a concentration-dependent manner (P < 0.05). However, mRNA expression of Caspase-7 was down-regulated first and then up-regulated, while mRNA expression of p21 was up-regulated first and then down-regulated. CONCLUSION: There is a IFN-γ-STAT1 pathway in gastric adenocarcinoma tissue and SGC7901 cell line. IFN-γ-STAT1 could upregulate the expression of Caspase-7 and p21 in gastric adenocarcinoma, but could not induce apoptosis. The downstream molecular of IFN-γSTAT1 pathway has different expression features in mRNA and protein expression level in gastric adenocarcinoma.