Correlation Between RAB27B and p53 Expression and Overall Survival in Pancreatic Cancer

OBJECTIVES: RAB27B is a member of the Rab family GTPases involved in vesicle trafficking, and p53 has recently been implicated in regulating the exosome secretion pathway. Because exosome secretion plays an important role in modulating tumor microenvironment and invasive growth, we hypothesized that RAB27B and p53 expression might be associated with the aggressive behavior in pancreatic ductal adenocarcinoma, one of the most deadly human malignancies. METHODS: We determined protein expression of RAB27B and p53 in 260 pancreatic tissues (186 malignant and 74 normal or benign) by immunohistochemistry analysis on tissue microarray and their correlation with patients' clinical parameters and overall survival. RESULTS: We found that a high RAB27B protein expression (RAB27B(+)) was significantly associated with perineural and vascular invasion, as well as distant metastasis. Patients with a high RAB27B expression had significantly poorer overall survival in both univariate and multivariate analyses. A significant correlation between RAB27B and p53 expression was observed. CONCLUSIONS: Our data indicate that RAB27B expression is an independent prognostic marker for pancreatic ductal adenocarcinoma and suggest that RAB27B-regulated exosome secretion pathway represents a novel therapeutic target in pancreatic cancer.