Expression of phosphorylated caspase-9 in gastric carcinomas

Alterations of caspases, the main executioners of apoptosis, have been described in human cancers. Caspase-9 plays a crucial role in the initiation phase of the intrinsic apoptosis pathway. Caspase-9 is phosphorylated at Thr125 through the mitogen-activated protein kinase (MAPK) pathway, and this phosphorylation is associated with inhibition of caspase-9 activation. The aim of this study was to explore whether phosphorylated caspase-9 (p-caspase-9) expression could be a characteristic of gastric carcinomas. We analyzed expression of p-caspase-9 protein in 60 gastric adenocarcinomas by immunohistochemistry using a tissue microarray approach. p-caspase-9 was detected in 33 of the 60 carcinomas (55%). Both early and advanced gastric carcinomas expressed p-caspase-9. There was no significant association of p-caspase-9 expression with clinocopathological characteristics, including invasion, metastasis and stage. In contrast to gastric cancer cells, epithelial cells in normal gastric mucosa showed no or only weak expression of p-caspase-9. Taken together, these results indicate that caspase-9 is frequently phosphorylated in gastric carcinomas, and that the phosphorylation of caspase-9 might be an inhibitory mechanism of caspase-9-mediated apoptosis in gastric carcinomas. Increased expression of p-caspase-9 in malignant gastric epithelial cells compared to normal mucosal epithelial cells suggests that p-caspase-9 expression might play a role in gastric carcinoma development.