Sameshima Y, Tsunematsu Y, Watanabe S, Tsukamoto T, Kawa-ha K, Hirata Y, Mizoguchi H, Sugimura T, Terada M, Yokota J
National Cancer Center Research Institute, Tokyo, Japan.
J Natl Cancer Inst. 1992 May 6;84(9):703-7. doi: 10.1093/jnci/84.9.703.
Germ-line p53 mutations appear to be inherited among the members of families diagnosed with Li-Fraumeni syndrome (LFS). The mutations detected in those families to date have been clustered in exon 7 of the p53 gene and, typically, have been single-base substitutions resulting in amino acid changes.
Our aim was to define the spectrum of p53 mutations associated with LFS.
From seven cancer-prone families identified by selecting members with childhood adrenocortical carcinoma as probands, we chose two families, each of which had two members from whom specimens could be obtained for genetic analysis. To detect germ-line p53 gene mutations in these individuals, we performed polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis with Taq polymerase and oligonucleotide primers specific for p53 gene sequences. Genomic DNA extracted from fresh tissue samples and paraffin-embedded tumor samples was amplified, denatured, and electrophoresed on neutral polyacrylamide gels. PCR amplification was also carried out using total RNA from adrenocortical carcinoma samples of the proband in family 1. PCR products were purified, subcloned, and sequenced.
We detected novel germ-line p53 mutations in affected members of both cancer-prone families. In the proband of family 1, a single-base deletion was detected at the first nucleotide of codon 307 in exon 8 of the p53 gene, resulting in a premature stop codon in exon 10. In family 2, we detected an A to C transversion at the second nucleotide of codon 286 in exon 8, both in DNA isolated from the adrenocortical tumor of the proband and in DNA isolated from the astrocytoma of the proband's father. This single-base substitution resulted in an amino acid substitution of alanine for glutamic acid. Both of these mutations are located outside the highly conserved region of the p53 gene where mutations in patients with LFS have been reported previously.
Our results indicate that a wide range of germ-line p53 mutations is inherited in members of diverse-cancer-prone families.
种系p53突变似乎在被诊断为李-佛美尼综合征（LFS）的家族成员中具有遗传性。迄今为止，在这些家族中检测到的突变集中在p53基因的外显子7中，并且通常是导致氨基酸变化的单碱基替换。
我们的目的是确定与LFS相关的p53突变谱。
从通过选择患有儿童肾上腺皮质癌的成员作为先证者而确定的7个癌症易患家族中，我们选择了两个家族，每个家族有两名成员，可从他们身上获取标本进行基因分析。为了检测这些个体中的种系p53基因突变，我们使用Taq聚合酶和针对p53基因序列的寡核苷酸引物进行聚合酶链反应（PCR）-单链构象多态性分析。从新鲜组织样本和石蜡包埋的肿瘤样本中提取的基因组DNA进行扩增、变性，并在中性聚丙烯酰胺凝胶上进行电泳。还使用来自家族1先证者的肾上腺皮质癌样本的总RNA进行PCR扩增。PCR产物被纯化、亚克隆并测序。
我们在两个癌症易患家族的患病成员中检测到了新的种系p53突变。在家族1的先证者中，在p53基因外显子8的密码子307的第一个核苷酸处检测到一个单碱基缺失，导致外显子10中出现一个提前终止密码子（UAG）。在家族2中，我们在先证者的肾上腺皮质肿瘤分离的DNA以及先证者父亲的星形细胞瘤分离的DNA中，均检测到外显子8中密码子286的第二个核苷酸处发生了A到C的颠换。这种单碱基替换导致氨基酸由谷氨酸替换为丙氨酸。这两种突变都位于p53基因的高度保守区域之外，而此前报道的LFS患者的突变位于该区域。
我们的结果表明，多种癌症易患家族的成员中遗传性种系p53突变范围广泛。
