Miyaki M, Konishi M, Kikuchi-Yanoshita R, Enomoto M, Igari T, Tanaka K, Muraoka M, Takahashi H, Amada Y, Fukayama M
Department of Biochemistry, Tokyo Metropolitan Institute of Medical Science, Japan.
Cancer Res. 1994 Jun 1;54(11):3011-20.
Mutation of the adenomatous polyposis coli (APC) gene was analyzed in 500 colorectal tumors from 70 familial adenomatous polyposis (FAP) and 102 non-FAP patients and in normal tissues from 119 FAP patients, using polymerase chain reaction-single-strand conformation polymorphism and direct sequencing methods. These tumors were histopathologically diagnosed. Sixty-eight germ line mutations (62% deletion, 9% insertion, and 29% single-base substitution) and 241 somatic mutations (56% deletion, 12% insertion, and 32% single-base substitution) were detected. All mutations formed stop codons resulting in truncated APC proteins, except for one germ line mutation. Differences were found between somatic and germ line mutations, including 3 new hot spots of mutation at codons 1378, 1450, and 1487-1490, which frequently occurred in somatic mutations but not in germ lines. The frequency of mutation in each histopathological type of FAP tumor was 53% in moderate adenoma, 64% in severe adenoma, 52% in intramucosal carcinoma, and 33% in invasive carcinoma, whereas the loss of heterozygosity including the APC gene increased with development to each histopathological type. A similar tendency was observed in non-FAP tumors. Additionally, we found 10 FAP tumors that had both somatic mutation and loss of heterozygosity. These tumors were assumed to have developed from moderate adenomas with germ line and somatic mutations, followed by deletion of the allele with germ line mutation. These results suggest that inactivation of the APC gene by two mutations is involved in the development of moderate adenoma, and loss of heterozygosity of the APC gene is associated with further development to carcinoma. It was also observed that the distribution of 75 somatic mutations from one FAP patient on the APC sequence was similar to the distribution of 159 somatic mutations from 83 patients with FAP and non-FAP, which suggests that the position of somatic mutation is mostly due to the APC sequence itself.
采用聚合酶链反应-单链构象多态性和直接测序方法，对70例家族性腺瘤性息肉病（FAP）患者和102例非FAP患者的500例结直肠肿瘤以及119例FAP患者的正常组织中的腺瘤性息肉病大肠杆菌（APC）基因进行了分析。这些肿瘤均经组织病理学诊断。共检测到68个种系突变（62%为缺失、9%为插入、29%为单碱基替换）和241个体细胞突变（56%为缺失、12%为插入、32%为单碱基替换）。除一个种系突变外，所有突变均形成终止密码子，导致APC蛋白截短。在体细胞突变和种系突变之间发现了差异，包括密码子1378、1450和1487 - 1490处3个新的突变热点，这些热点在体细胞突变中频繁出现，但在种系中未出现。FAP肿瘤各组织病理学类型的突变频率分别为：中度腺瘤53%、重度腺瘤64%、黏膜内癌52%、浸润性癌33%，而包括APC基因在内的杂合性缺失随各组织病理学类型的发展而增加。在非FAP肿瘤中也观察到类似趋势。此外，我们发现10例FAP肿瘤同时存在体细胞突变和杂合性缺失。这些肿瘤被认为是由具有种系和体细胞突变的中度腺瘤发展而来，随后发生了具有种系突变的等位基因缺失。这些结果表明，两个突变导致的APC基因失活参与了中度腺瘤的发生，而APC基因的杂合性缺失与癌的进一步发展相关。还观察到一名FAP患者的75个体细胞突变在APC序列上的分布与83例FAP和非FAP患者的159个体细胞突变的分布相似，这表明体细胞突变的位置主要取决于APC序列本身。
