Wiseman R W, Cochran C, Dietrich W, Lander E S, Söderkvist P
Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709.
Proc Natl Acad Sci U S A. 1994 Apr 26;91(9):3759-63. doi: 10.1073/pnas.91.9.3759.
To identify the potential involvement of tumor-suppressor gene inactivation during neoplastic development in B6C3F1 mice, genetic losses were determined from allelotypes of butadiene-induced lung and mammary adenocarcinomas. By using length polymorphisms in restriction fragments and simple sequence repeats, or "microsatellites," markers on each autosome were analyzed for allele losses in tumor DNAs. Losses of heterozygosity on chromosome 11 were observed at several loci surrounding the p53 tumor-suppressor gene (Trp53) in 12 of 17 mammary tumors and 2 of 8 lung tumors. Although most of these alterations appeared to result from nondisjunction, at least two examples of somatic recombination or deletion were also observed. Southern analysis revealed a homozygous deletion of the remaining Trp53 allele of one of these mammary tumors. Losses of heterozygosity were also detected at the Rb-1 tumor-suppressor gene in 7 of 17 mammary tumors and 1 lung tumor. Finally, frequent allele losses were observed on chromosome 4 in lung tumors. Analysis of nine chromosome 4 loci defined an interstitial deletion containing the Ifa gene cluster in one of the lung tumors. A tumor-suppressor gene was previously mapped to this region of chromosome 4 in studies with somatic cell hybrids. In addition, homozygous deletions have been reported in a homologous region of human chromosome 9p for acute lymphocytic leukemias, glioblastomas, melanomas, and lung carcinomas. These findings suggest that the inactivation of tumor-suppressor genes including Trp53, Rb-1, and an unidentified gene on chromosome 4 plays a significant role during carcinogenesis in mice.
为了确定肿瘤抑制基因失活在B6C3F1小鼠肿瘤发生过程中的潜在作用，通过丁二烯诱导的肺和乳腺腺癌的等位基因型来确定基因缺失情况。利用限制性片段长度多态性和简单序列重复，即“微卫星”，分析每个常染色体上的标记在肿瘤DNA中的等位基因缺失情况。在17个乳腺肿瘤中的12个以及8个肺肿瘤中的2个中，在p53肿瘤抑制基因（Trp53）周围的几个位点观察到11号染色体上的杂合性缺失。尽管这些改变大多似乎是由于不分离导致的，但也观察到至少两个体细胞重组或缺失的例子。Southern分析显示其中一个乳腺肿瘤的剩余Trp53等位基因发生了纯合缺失。在17个乳腺肿瘤中的7个以及1个肺肿瘤中还检测到Rb - 1肿瘤抑制基因的杂合性缺失。最后，在肺肿瘤中观察到4号染色体上频繁的等位基因缺失。对9个4号染色体位点的分析确定了一个肺肿瘤中包含Ifa基因簇的中间缺失。在体细胞杂交研究中，一个肿瘤抑制基因先前被定位到4号染色体的这个区域。此外，在人类9号染色体p臂的同源区域，急性淋巴细胞白血病、胶质母细胞瘤、黑色素瘤和肺癌中也有纯合缺失的报道。这些发现表明，包括Trp53、Rb - 1以及4号染色体上一个未确定的基因在内的肿瘤抑制基因失活在小鼠致癌过程中起重要作用。
