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

Abstract

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 are reported to be different between Europeans and Japanese. The present study was designed to compare the incidences and profile of K-ras PMs and ras-p21 expression in primary invasive ductal carcinoma (IDC) of the pancreas between Japanese and Chinese. The specimens included 51 Japanese and 34 Chinese patients with the primary IDC of the pancreas. K-ras PMs were tested by allele specific oligonucleotide dot blot hybridization methods and ras-p21 expression was stained by the immunohistochemical method. K-ras PMs were detected in 48 Japanese IDCs (94%) and in 24 Chinese ones (71%). There was a significant difference between the two groups. The GAT mutation was more frequent both in Japanese (61%, 33/54) and in Chinese (60%, 18/30) IDCs. The transitions/transversions 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 Chinese IDCs (71%). There was a significant difference between the two groups. The expression of p21 and the patterns of K-ras PMs did not show any significant influence on the survival of the patients both in Japanese and Chinese. In the present study, Chinese IDC had a lower frequency of K-ras PMs in codon 12 than Japanese IDC. The pattern of K-ras PMs in Chinese IDC was different from that in Japanese and European IDC, respectively. Ki-ras PM and p21 expression were frequently seen both in Japanese and Chinese patients with pancreatic cancer. Factors such as lifestyle and environment may have influences on pancreatic carcinogenesis in various populations.