Comparison of K-ras point mutations at codon 12 and p21 expression in pancreatic cancer between Japanese and Chinese patients

Background and Objectives: K-ras (Kirsten-ras) point mutation (PM) in codon 12 are suggested to be significantly associated with the tumorigenesis of pancreatic cancer. The incidences of K-ras PMs in human pancreatic cancer a re reported to be different between Europeans and Japanese. The present stu dy was designed to compare the incidences and profile of K-ras PMs and ras- p21 expression in primary invasive ductal carcinoma (LDC) of the pancreas b etween Japanese and Chinese. Methods: The specimens included 51 Japanese and 34 Chinese patients with th e primary IDC of the pancreas. K-ras PMs were tested by allele specific oli gonucleotide dot blot hybridization methods and ras-p21 expression was stai ned by the immunohistochemical method. Results: K-ras PMs were detected in 48 Japanese IDCs (94%) and in 24 Chines e ones (71%). There was a significant difference between the two groups. Th e GAT mutation was more frequent both in Japanese (61%, 33/54) and in Chine se (60%. 18/30) IDCs. The transitions/trans versions ratio in the Japanese group was 2.4 in this study. By contrast, that in the Chinese group was 1.5 . The expression of p21 was detected in 24 Japanese IDCs (47%) and in 24 Ch inese IDCs (71%). There was a significant difference between the two groups . The expression of p21 and the patterns of R-ras PMs did not show any sign ificant influence on the survival of the patients both in Japanese and Chin ese. In the present study, Chinese IDC had a lower frequency of K-ras PMs i n codon 12 than Japanese IDC. The pattern of K-ras PMs in Chinese IDC was d ifferent from that in Japanese and European IDC, respectively. Conclusions: Ki-ras PM and p21 expression were frequently seen both in Japa nese and Chinese patients with pancreatic cancer. Factors such as lifestyle and environment may have influences on pancreatic carcinogenesis in variou s populations. J. Surg. Oncol. 2000:75:176-185. (C) 2000 Wiley-Liss, Inc.