The Value Of Alterations In K-ras Gene,DPC4 Gene For Diagnosis Of Pancreatic Cancer

Objective To evaluate their diagnostic value in pancreatic adenocarcinoma ,the alterations in the K-ras codon12 point,DPC4 gene were detected in both pancreatic adenocarcinoma and noncarcinoma. Methods 23 pancreatic adenocarcinoma specimens and 12 noncarcinoma of pancreatic disorder specimens were obtained.DNA was extrated by two different methods.K-ras codon 12 point mutation were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).The products were analysed in 12% polyacrylamide gel electrophoresis with silver staining and the presence of 135 base pairs fragment was considered as positive result.A negative(no DNA)control was run with each PCR analysis.All specimens were monitored with polymersae chain reaction(PCR),single-strand conformation polymorphism(SSCP) analysis to demonstrate mutation in 2 exons(8 and 11) of DPC4 gene,and the presence of abnormal DNA bands was considered as positive result compared with control.The delection in DPC4 gene was amplified by PCR together with K-ras gene exon 1.The products were analysed in 12% polyacrylamide gel electrophoresis with silver standing and the presence of K-ras DNA band without DPC4 gene band was considered as positive.DNA extrated from normal gastric mucosa was used as both positive control of DPC4 gene PCR and negative control of mutation in DPC4 gene of SSCP.All of tests were repeated 2 or 3 times.Results The rate of k-ras codon 12point mutation in pancreatic adenocarcinoma and noncarcinoma of pancreatic disorder is 65.2%(15/23),33.3%(4/12),respectively. Mutation in the DPC4 gene wasfound in 6 of 23 cases.3 in exon 8,2 in exon 11b,1 in exon 8,11a. 3 of 6 without k-ras gene mutation. None delection in DPC4 was found in both pancreatic adenocarcinoma and noncarcinoma.The diagnosis of pancreatic adenocarcinoma connected k-ras with DPC4 gene was with sensitivity 78.3%, specificity 100%, positive predictive value 82%, negative predictive value 70.6% and diagnosis accordance rate 85.7%,respectively. Conclusions1 K-ras codon 12 point mutation in pancreatic adenocarcinoma was much higher than that in nonadenocarcinoma of pancreatic disorders (65.2%,33.3%,respectively.P<0.05) , Which indicates that k-ras gene point mutation is useful for diagnisis of pancreatic cancer.2 The most manifest of alterations in DPC4 gene in paraffin-embedded pancreatic adenocarcinoma specimens was mutation,whereas delection in DPC4 gene was uncommon.3 The sensitivity, specificity, positive predictive value, and diagnosis accordance rate for diagnosis of pancreatic adenocarcinoma were increased when connected k-ras with DPC4 gene. So detection of DPC4 gene may be complementary to k-ras mutation.4 K-ras gene point mutation was found in some nonadenocarcinoma of pancreatic disorders,such as chronic pancreatitis,which may be at high risk for the development of pancreatic cancer. A case with k-ras mutation should be followed-up so as to diagnose early pancreatic cancer.