Combined detection of p16 aberrant methylation and K-ras gene mutation in pancreatic juice for diagnosis of pancreatic cancer

Abstract

Objective To investigate the diagnostic significance of detecting p16 aberrant meth-ylation and K-ras gene mutation in pancreatic juice for pancreatic cancer. Methods Aberrant p16 methylation was detected using the methylation-specific PCR (MSP) in pure pancreatic juice(PPJ) col-lected from the pancreatic duct through a nasopancreatic tube put under endoscopic retrograde cholan-giopancreatography (ERCP). K-ras gene 12 codon mutation was detected using the m PCR-RFLP in the pure PPJ. Results The DNA was obtained from PPJ through a nasopancreatic tube. Aberrant p16 methylation and K-ras gene mutation were detected in the same samples of PPJ. Sensitivity, specifici-ty,positive predictive values, negative predictive values and accuracy of HE staining for pancreatic cancer were 40%, 100%, 100%,45.4% and 60.0%, respectively. Of the 20 cases of pancreatic canc-er,K-ras gene mutation was detected in 14 (70%) and the p16 gene was shown to be methylated in 7(35%). Of the 8 cases of chronic pancreatitis,K-ras gene mutation was detected in 2 (25%). Of the 2cases of mucinous cystoadenoma of pancreas,K-ras gene mutation was detected in 1 (50%). Aberrant methylation of p16 was not detected in pancreatic juice samples from patients with chronic pancreatitis and mucinous cystoadenoma of pancreas. Sensitivity, specificity, positive predictive values, negative predictive values and accuracy of detection K-ras gene mutation for pancreatic cancer were 70%, 70%,82.4%,53.8% and 70.0%, respectively. The sensitivity, specificity, positive predictive values, nega-tive predictive values and accuracy of detection of K-ras gene mutation and p16 methylation for pancre-atic cancer were 70%, 100%, 100%,62.5% and 80%, respectively. Conclusion Pancreatic juice can be used for molecular analysis of pancreatic juice obtained using nasopanereatic drainage during ERCP.Detecting aberrant methylation of p16 and K-ras gene mutation from pancreatic juice may be a new tool to diagnose pancreatic cancer. Key words: Pancreatic cancer; ERCP; Pancreatic neoplasms; Methylation; K-ras gene