ANALYSIS OF K-RAS GENE-MUTATIONS IN PERIAMPULLARY CANCERS, GALLBLADDER CANCERS AND CHOLANGIOCARCINOMAS FROM PARAFFIN-EMBEDDED TISSUE-SECTIONS

Point mutations of the K-ras gene were analyzed in 25 periampullary ca ncers (21 ampulla vater cancers, two common bile duct cancers and two duodenal cancers), two gallbladder cancers and six cholangiocarcinomas . DNA extracted from the paraffin-embedded tissues was amplified with the polymerase chain reaction and subsequently analyzed by direct cycl e sequencing at codons 12, 13 and 18 of the Ii-ras gene. Codon 61 was first screened with single strand conformation polymorphism and then s equenced by direct cycle sequencing. No point mutation was found in an y of tile 25 periampullary cancers or the two gallbladder cancers. The se results are similar to previous reports. Mutation of the K-ras gene seems not to play an important role in tumorigenesis of periampullary cancer. In two of six (33%) cholangiocarcinoma patients, point mutaio ns were found. Both mutations were transitions, GGT to GAT at codon 12 . The incidence of mutation was greater than that in Thailand (about 8 %) but less than that in Japan (about 60%). Mutation of tile K-ras gen e may play varied roles in the tumorigenesis of cholangiocarcinoma, de pending on geographic area.