Quantitative analysis of VEGF-C mRNA of extrahepatic cholangiocarcinoma with real-time PCR using samples obtained during endoscopic retrograde cholangiopancreatography

Abstract

Objective. Vascular endothelial growth factor (VEGF)-C overexpression in extrahepatic cholangiocarcinoma (ECC) has been shown to be correlated with lymph node metastasis. The intensity of immunohistochemical staining of VEGF-C protein in surgical samples has been used as index of VEGF-C overexpression in previous studies. The aim of the study was to examine if VEGF-C overexpression in ECC could be preoperatively detected by using samples obtained during ERCP. Methods. Consecutive patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) for biliary stricture during the study period were prospectively analyzed. VEGF-C mRNA was quantified by real-time PCR methods using endoscopic samples obtained during ERCP. The high intensity of immunohistochemical staining of VEGF-C protein in surgical samples was used for the reference standard of VEGF-C overexpression. The level of S100P mRNA which was a novel diagnostic marker of ECC was also quantified to evaluate whether the endoscopic samples contained ECC cells. Results. Twenty-five patients were enrolled in this study. Eighteen patients were diagnosed as ECC and seven patients were diagnosed as benign biliary structure. Nine of eighteen patients with ECC, who showed positive S100P mRNA in endoscopic samples and received surgical resection, were finally analyzed. Receiver operating characteristics analysis yielded VEGF-C mRNA cut-off value of 3.85 for detection of VEGF-C overexpression, and the diagnostic performance of VEGF-C mRNA measurement in the endoscopic sample for VEGF-C overexpression reached sensitivity of 75.0%, specificity of 100%, and accuracy of 88.9%. Conclusion. The quantification of VEGF-C mRNA of ECC with real-time PCR using endoscopic samples was useful for preoperative detection of VEGF-C overexpression.