Detection of p53 Gene Mutations in the Supernatant of Pancreatic Juice and Plasma from Patients with Pancreatic Carcinomas

Abstract

AIM: The sensitivity of pure pancreatic juice (PPJ) cytology for the diagnosis of pancreatic carcinoma (PCa) is still low. The usefulness of genetic analyses of PPJ seems to be limited because of insufficient sensitivity or false positivity. To improve the molecular diagnosis of PCa, we analyzed mutations of p53 together with K-ras in DNA extracted not only from the sediment but also from the supernatant of PPJ samples. METHOD: Polymerase chain reaction-single-strand conformation polymorphism and direct sequencing were used for analyses of p53 mutations in exons 5-8. K-ras mutations at codon 12 were examined by mutant allele-specific amplification. RESULTS: In PPJ supernatant from patients with PCa, p53 and K-ras mutations were detected in 42.9% (9 of 21) and 81.0% (17 of 21) of cases, respectively. The incidence of p53 and K-ras mutations in the sediment was 28.6% and 71.4%, respectively. By a combination assay with supernatant and sediment, p53 mutations were detected in 52.4% (11 of 21) of PCa cases. Moreover, p53 mutations were detected in 7 of 15 (46.7%) cases of PCa in which the cytologic diagnosis was negative. Among 25 patients with chronic pancreatitis (CP), none harbored mutant p53, although K-ras mutations were detected at an incidence of 28% (7 of 25) in the supernatant and 20% (5 of 25) in the sediment. In addition, mutant bands of p53 in plasma were detected in 2 of 11 patients with PCa in whom p53 mutations were detectable in PPJ. CONCLUSION: These results suggest that the sensitivity of detection for p53 mutations with high cancer specificity could be improved by using the Sup in PPJ samples of PCa. Genetic analysis of p53 could complement PPJ cytology. p53 mutations were detectable in PCa from plasma samples.