K-ras and p53 gene mutations in colorectal cancer in 57 Japanese patients.
Fifty-eight tissue specimens from 57 Japanese patients with colorectal cancer were analyzed for the K-ras and p53 gene mutations by polymerase chain reaction-single strand conformation polymorphism analysis and direct sequencing. K-ras mutations were detected in 21 cases (36.2%) and p53 mutations in 20 cases (34.5%). Eight specimens had both gene mutations. The K-ras mutation was associated with higher degrees of differentiation (p = 0.0019). The P53 mutation was associated with Duke B to D staging (p = 0.028), lymph vessel invasion (p = 0.021), and venous invasion (p = 0.03). Interestingly, a mutation in only exon 7 of the P53 gene was associated with lymph node metastasis. These results suggest the important effect of the mutations of the K-ras and p53 genes, especially p53 gene on colorectal carcinogenesis in Japanese patients. The grades of malignancy of the specimens with the mutations in both genes were not different significantly from those with a single (K-ras or p53) or no mutation, suggesting no cooperation between K-ras and p53 gene mutations on carcinogenesis or tumorigenesis.