Abstract

Context The tumor protein p53-induced nuclear protein 1 (TP53INP1) gene was found using DNA microarray technology as an overexpressed gene in acute pancreatitis. However, expression of TP53INP1 in chronic pancreatitis has not been previously reported. Objective This study investigated TP53INP1 gene expression and its relationship with p53 and apoptosis in spontaneous chronic pancreatitis in the Wistar-Bonn/Kobori rat. Methods Ninety four-week-old male Wistar- Bonn/Kobori rats were fed a special breeding  diet until sacrifice. Camostat mesilate (n=30) or a herbal medicine (Saiko-keishi-to; n=30) were mixed with the diet, while the other 30 rats were untreated. The rats were sacrificed every 4 weeks for 20 weeks, and the pancreas was examined. In addition, 6 four-week-old male Wistar-Bonn/Kobori rats were sacrificed and studied as starting reference. Finally, Wistar rats (n=36) were studied as controls. Main outcome measure :TP53INP1 Mrna expression was determined by reverse transcription-polymerase chain reaction using semi-quantitative analysis, direct sequencing  and in situ hybridization. Results TP53INP1 mRNA was strongly expressed at 12 weeks when chronic pancreatitis developed, with a second peak at 20 weeks. The expression kinetics of TP53INP1 mRNA  paralleled acinar cell apoptosis assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. The p53 mRNA expression showed a single peak at 12 weeks. In situ hybridization revealed that TP53INP1 mRNA was expressed mainly in acinar cells. Therapeutic drugs such as camostat mesilate and a herbal medicine Saiko-keishi-to suppressed the TP53INP1 mRNA expression. TP53INP1 mRNA induction in acinar cells was confirmed with in vitro experiments using an arginine-induced rat pancreatic acinar AR4-2J cell injury model. Conclusions TP53INP1 expression may reflect the acute-phase response and apoptosis of acinar cells in the course of chronic pancreatitis.