DETECTION OF POINT MUTATIONS IN K-RAS GENE AT CODON-12 IN BILE FROM PERCUTANEOUS TRANSHEPATIC CHOLEDOCHAL DRAINAGE TUBES FOR DIAGNOSIS OF BILIARY STRICTURES

Detection of K-ras mutations at codon 12 constitutes one modality for diagnosis of pancreatic tumors. We attempted to detect K-ras mutations in DNA from bile collected through percutaneous transhepatic choledoc hal drainage (PTCD) tubes as a diagnostic approach to biliary strictur es. Since bile salts induce cell damage, we first investigated the deg eneration of cells according to bile exposure time using cell lines. H igh-mel-wt DNA could be extracted from cells exposed to bile for 6 h, but not from those exposed for 12 h. However, DNA exposed to bile for up 12 h could be amplified by the polymerase chain reaction (PCR) meth od. Therefore, K-ras mutations in fresh bile specimens collected from 15 patients through PTCD tubes were examined using PCR with restrictio n enzyme digestion. K-ras mutations were found in five out of five (10 0%) pancreatic cancers, all of which were negative according to cytodi agnosis of the same bile. On the other hand, K-ras mutations were not detected in bile from biliary tract cancers or metastatic neoplasms, e xcept for one bile duct carcinoma and one metastatic case. Thus, altho ugh K-ras mutation alone is not an absolute marker for cancer, detecti on of K-ras mutations in fresh bile from PTCD tubes is a useful adjunc t for diagnosis of pancreatic carcinomas in cases of biliary tract str ictures.