Tumor-specific Expression of Insulin-like Growth Factor II mRNA-binding Protein 3 Independently Predicts Worse Survival of Patients With Adenocarcinoma of the Ampulla of Vater.

Background/Aim: Insulin-like growth factor II mRNA-binding protein 3 (IMP3) plays an important role in the adhesion, invasion, and metastasis of tumor cells. Although emerging evidence suggests that IMP3 promotes tumor progression in several malignancies, the expression of IMP3 and its prognostic implication in adenocarcinoma of the ampulla of Vater (AVAC) has not been clarified to date. Materials and Methods: The IMP3 expression status in 87 AVAC tissues was examined using immunostaining, and its association with various clinicopathological features and outcome of patients with AVAC was investigated. Results: The vast majority (87.4%) of AVAC cases displayed at least focal cytoplasmic and membranous IMP3 immunoreactivity in tumor cells, whereas IMP3 expression was consistently absent from normal biliary epithelial cells. Tumor-specific IMP3 expression was associated with submucosal and pancreatic invasion, which were not identified in the corresponding hematoxylin and eosin-stained slides. This finding led to up-staging of the pathological tumor stage in two cases of well-differentiated AVAC. In addition, high IMP3 expression was significantly associated with a poorly differentiated histology (p=0.026). Survival analyses revealed that high IMP3 expression independently predicted shorter recurrence-free (p=0.003) and overall (p=0.029) survival. Conclusion: Our study demonstrated tumor-specific IMP3 expression in AVAC, which will be helpful in determining invasion depth and tumor extent in patients with well-differentiated tumors, as well as indicating worse survival of patients with AVAC. Our data highlight IMP3 expression status as a potential diagnostic and prognostic marker for AVAC.