PGP9.5 Abnormal Expression And Its Significance In Pancreatic Endocrine Tumors

Purpose There is a lack of reliable biomarker to distinguish benign and malignant form of pancreatic endocrine tumors as well as to predict the prognosis of the disease. The aim of this study is to identify if PGP9.5protein was expressed in pancreatic endocrine tumors, and if the alteration of PGP9.5expression could be used to distinguish benign and malignant pancreatic endocrine tumors and to predict the outcome of the patients. In addition, we try to figure out the molecular mechanisms underlying the expression of PGP9.5in these tumors.Experimental Design Expression of PGP9.5was tested in226pancreatic endocrine tumors by immunohistochemical staining. One hundred and sixty-seven patients with pancreatic endocrine tumors were followed up. The data were correlated with clinical-pathological characteristics, using both univariate and multivariate statistical analysis. We detected the methylation status of gene promoter by MSP and bisulfated sequencing.Results We found that PGP9.5protein was expressed in93of226(41.2%) pancreatic endocrine tumors, whereas in normal pancreatic tissues or paired pancreatic tissues, the protein was found in part of islet cells (P=7.98x10-12). The expression rate of PGP9.5in benign and malignant pancreatic endocrine tumors were significantly different (47.4%vs.28.8%, respectively, P=0.008), and the reduced expression of PGP9.5or loss of expression was associated with metastases (P=0.023). The rate of the expression of PGP9.5was significantly higher in functional tumors than in non-functional ones (P=0.001). The expression of PGP9.5is not significantly correlated with prognosis.Conclusion PGP9.5protein may be a novel molecular marker to distinguish benign and malignant form of pancreatic endocrine tumor, rather than a prognostic marker.