Xu W, Yang D, Wan Y
Department of Surgery, Beijing Medical University.
Zhonghua Zhong Liu Za Zhi. 1995 Sep;17(5):328-31.
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.
我们引入了两种改良的检测系统，即聚合酶链反应-单链构象多态性分析（PCR-SSCP）和聚合酶链反应直接测序法，用于检测22例结直肠癌及1个转移淋巴结中p53基因第7外显子的结构畸变。数据表明，27.2%（6/22）的结直肠癌及1个转移淋巴结在第7外显子的密码子245、251、259和260处存在点突变。所有突变中有一半是密码子245处的G:c到A:T转换。其他突变模式为碱基插入和缺失。本研究中p53基因第7外显子的所有阳性点突变均存在于结肠癌中。p53基因第7外显子的点突变通常与低分化原发性癌相关（P = 0.0178），且该疾病Dukes C期的突变率高于Dukes A期和B期（P = 0.0361）。因此，原发性结直肠癌及区域淋巴结中p53基因第7外显子的点突变可能可识别出一组疾病侵袭性更强的结直肠癌患者，并且可能作为评估结直肠癌预后的一种新的肿瘤标志物。
