Mutations in the promoter reveal a cause for the reduced expression of the human manganese superoxide dismutase gene in cancer cells.
Mutations in the promoter reveal a cause for the reduced expression of the human manganese superoxide dismutase gene in cancer cells.
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启动子突变揭示了癌细胞中人锰超氧化物歧化酶基因表达减少的原因。
DOI：
10.1038/sj.onc.1202265
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
StClair,DK
中科院分区：
文献类型：
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作者：
Xu,Y;Krishnan,A;Wan,XS;Majima,H;Yeh,CC;Ludewig,G;Kasarskis,EJ;StClair,DK
锰超氧化物歧化酶（MnSOD）已被证明在预防癌症的发展中发挥重要作用。MnSOD活性在许多转化细胞和肿瘤组织中降低。我们先前表明，癌细胞中MnSOD活性水平的降低不是由于MnSOD蛋白一级结构的缺陷，而是由于基因表达的缺陷。为了阐明人MnSOD在癌症中表达减少的原因，我们研究了正常人细胞系和各种人肿瘤细胞系中MnSOD基因调控区的核苷酸序列。从正常人基因组DNA文库中分离出MnSOD基因5′侧翼区3.4kb的DNA片段，用于测定MnSOD启动子的DNA序列。用PCR方法扩增人MnSOD基因5′侧翼区3.4kb片段。序列分析确定了三个杂合突变的近端区域的启动子在五个人类肿瘤细胞系。这些突变聚集在人MnSOD启动子的富含GC的区域周围，改变AP-2的结合模式，并导致使用荧光素酶报告基因测定系统的转录活性降低。这些结果表明，MnSOD在某些肿瘤细胞中的表达水平降低，至少部分是由于启动子区的DNA序列的缺陷。
Manganese superoxide dismutase (MnSOD) has been shown to play an important role in preventing the development of cancer. MnSOD activity is reduced in many transformed cells and tumor tissues. We previously showed that the reduced level of MnSOD activity in cancer cells was not due to a defect in the primary structure of MnSOD protein, but rather was due to defects in gene expression. To elucidate the cause for the reduced expression of human MnSOD in cancer, we investigated the nucleotide sequence in the regulatory region of the MnSOD gene in a normal human cell line and various human tumor cell lines. A DNA fragment spanning 3.4 kb 5′ flanking region of the MnSOD gene isolated from a normal human genomic DNA library was used to determine the DNA sequence of MnSOD promoter. PCR primers were used for amplification of the 3.4 kb 5′ flanking region of the human MnSOD gene in cancer cells. Sequence analysis identified three heterozygous mutations in the proximal region of the promoter in five human tumor cell lines. These mutations, clustered around the GC-rich region of the human MnSOD promoter, change the binding pattern of AP-2 and lead to a reduction in transcription activity using a luciferase reporter assay system. These results suggest that the reduced level of MnSOD expression in some tumor cells is, at least in part, due to a defect in the DNA sequence of the promoter region.