Expression of p8 in human pancreatic cancer.

The p8 gene is a recently identified gene with mitogenic activity. p8 expression is induced in acute pancreatitis, pancreatic development, and regeneration. However, the expression of p8 in pancreatic cancer is not reported. We investigated p8 expression in 72 human pancreatic tissues, including 38 pancreatic cancers (PCs), by immunohistochemistry. p8 was overexpressed (positive cells >25% in 1,000 cells) in 71% (27 of 38) of PCs, but in only 17% (3 of 18) of chronic pancreatitis cases. There was no overexpression in mucinous cystadenoma or in normal pancreas. The p8 overexpression rate in PC was significantly higher than that in other conditions (P < 0.05). Reverse transcription-PCR analysis confirmed p8 mRNA overexpression (tumor/nontumor ratio >2) in 75% (3 of 4) of PCs. p8 was overexpressed also in human pancreatic cancer cell lines (MIA PaCa-2 and PANC-1). These results suggest that p8 is involved in the development of pancreatic cancer, reflecting its mitogenic activity.