Immunohistochemical analysis of apoptosis-inducing factor (AIF) expression in gastric carcinomas

Mounting evidence suggests that both survival and death of cells play an important role in tumorigenesis. Apoptosis-inducing factor (AIF), a mitochondrial protein, plays an important role in the caspase-independent apoptosis. Also, recent studies have demonstrated that AIF has an oxidoreductase function that confers survival on the cells. As the roles of AIF in cancers are largely unknown, it may be important to identify the expression pattern of AIF in cancer tissues. In this study, which aims at defining the role of AIF in gastric tumorigenesis, we analyzed the expression of AIF in 60 gastric adenocarcinomas using immunohistochemistry. AIF expression was detected in the cytoplasm in 42 cases (70%) of gastric carcinoma. We also analyzed AIF expression in early (EGC) and advanced gastric carcinomas (AGC). AIF was expressed in 25 (73%) of 34 intestinal-type cancers and in 17 (65%) of 26 diffuse-type cancers. However, there was no significant difference in AIF expression with respect to the histological subtypes or the depth of invasions, either. In normal gastric mucosal cells, parietal cells, but not other mucosal cells, expressed AIF. Increased expression of AIF in malignant gastric epithelial cells compared to the normal mucosal cells suggests that AIF expression may play a role in gastric tumorigenesis. Also, the data suggest that AIF expression may play a role in the function of the gastric parietal cells.