Patterns of K-ras codon 12 and 13 mutations found in pancreatic adenocarcinoma of 30 Chinese patients by microdissection, PCR and direct sequencing

Background and Aim: To our knowledge there are few reports on the K-ras mutation pattern of pancreatic adenocarcinoma from Chinese mainland patients. We examined surgically resected formalin-fixed, paraffin-embedded primary pancreatic adenocarcinoma tissue blocks for the presence of activating point mutations at codon 12 and 13 of the K-ras gene. Methods: Mutations were detected through the use of microdissection, polymerase chain reaction (PCR) and direct sequencing. The results were confirmed by reverse sequencing. Results: The combination of microdissection, PCR and direct sequencing techniques resulted in a rapid and sensitive detection of K-ras mutations at codon 12 and 13. Twenty-five (83%) of the 30 pancreatic adenocarcinomas examined harbored K-ras mutation. Among the 25 pancreatic adenocarcinomas, 24 showed K-ras mutation at codon 12 (11 with GGT-GTT, seven with GGT-GAT, four with GGT-CGT, and two with GGT-TGT), and only one showed a GGC-TGC mutation at codon 13. In this study most of K-ras mutations at codon 12 were at the second base (72%, 18/25) with a transition/transversion ratio of 1:1.57 (7/11). Conclusions: The mutation profiles of K-ras at codon 12 in our pancreatic adenocarcinoma samples were significantly different from those of European and Japanese samples.