[p53 gene point mutation in human colorectal carcinoma].

We introduced two modified assay systems, PCR-SSCP and PCR-direct sequencing for the identification of structure aberration at p53 exon 7 in 22 colorectal carcinomas and 1 metastatic lymph node. The data indicated that 27.2% (6/22) colorectal carcinomas and one metastatic lymph node were shown to contain the point mutations in codons 245, 251, 259 and 260 of exon 7. One half of all the mutations was G:c to A:T transition in codon 245. Other mutation patterns were base insertion and deletion. All positive point mutations of p53 exon 7 existed in colon carcinomas in this study. The point mutation in p53 exon 7 was usually associated with poorly differentiated primary carcinomas (P = 0.0178) and the mutation rate of was higher in Duckes C stage of the disease than in stage Duckes A and B (P = 0.0361). Thus p53 exon 7 point mutation in primary colorectal tumors and regional lymph nodes may identity a subgroup of colorectal cancer patients with more aggressive disease and may be as a new tumor markers for assessing the prognosis of colorectal carcinomas.