Functional promoter upstream p53 regulatory sequence of IGFBP3 that is silenced by tumor specific methylation.
Functional promoter upstream p53 regulatory sequence of IGFBP3 that is silenced by tumor specific methylation.
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DOI：
10.1186/1471-2407-5-9
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发表时间：
2005-01-20
期刊：
影响因子：
3.8
通讯作者：
Koide N
中科院分区：
文献类型：
--
作者：
Hanafusa T;Shinji T;Shiraha H;Nouso K;Iwasaki Y;Yumoto E;Ono T;Koide N
胰岛素样生长因子结合蛋白-3(IGFBP-3)是循环中胰岛素样生长因子(IGF)的载体，也是细胞内生长抑制信号的中介。已报道的IGFBP3基因有两个p53调控区，一个在启动子的上游，一个在内含子。我们先前报道了人肝细胞癌及其衍生细胞系中IGFBP-3基因启动子高甲基化的热点。由于热点位于假定的上游P53共有序列，这些P53共有序列是否具有真正的功能是一个有待回答的问题。在这项研究中，我们检测了p53诱导的IGFBP-3表达的IGFBP-3启动子上游的p53共有序列。在人肝母细胞瘤细胞系HepG2中对IGFBP-3启动子的缺失、突变和甲基化结构进行了活性评估。这些序列的缺失和突变在P53过表达的情况下完全取消了IGFBP-3的表达。在体外，这些p53共有序列的甲基化也抑制了IGFBP-3的表达。相反，在没有P53过表达的情况下，IGFBP-3的表达不受影响。进一步，我们通过凝胶迁移率改变实验观察到，当甲基化时，P53与启动子区域的结合减弱。根据这些观察，我们得出结论：IGFBP-3启动子上游的11个p53共有序列中有4个是P53诱导的IGFBP-3表达所必需的，这些序列的高甲基化选择性地抑制了P53诱导的HepG2细胞中IGFBP-3的表达。
Insulin-like growth factor binding protein (IGFBP)-3 functions as a carrier of insulin-like growth factors (IGFs) in circulation and a mediator of the growth suppression signal in cells. There are two reported p53 regulatory regions in the IGFBP3 gene; one upstream of the promoter and one intronic. We previously reported a hot spot of promoter hypermethylation of IGFBP-3 in human hepatocellular carcinomas and derivative cell lines. As the hot spot locates at the putative upstream p53 consensus sequences, these p53 consensus sequences are really functional is a question to be answered. In this study, we examined the p53 consensus sequences upstream of the IGFBP-3 promoter for the p53 induced expression of IGFBP-3. Deletion, mutagenesis, and methylation constructs of IGFBP-3 promoter were assessed in the human hepatoblastoma cell line HepG2 for promoter activity. Deletions and mutations of these sequences completely abolished the expression of IGFBP-3 in the presence of p53 overexpression. In vitro methylation of these p53 consensus sequences also suppressed IGFBP-3 expression. In contrast, the expression of IGFBP-3 was not affected in the absence of p53 overexpression. Further, we observed by electrophoresis mobility shift assay that p53 binding to the promoter region was diminished when methylated. From these observations, we conclude that four out of eleven p53 consensus sequences upstream of the IGFBP-3 promoter are essential for the p53 induced expression of IGFBP-3, and hypermethylation of these sequences selectively suppresses p53 induced IGFBP-3 expression in HepG2 cells.
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影响因子：
13
作者：
Clemmons, David R.
通讯作者：
Clemmons, David R.
DOI：
10.1093/jnci/88.9.601
发表时间：
1996-05-01
期刊：
JOURNAL OF THE NATIONAL CANCER INSTITUTE
影响因子：
--
作者：
Rocha, RL;Hilsenbeck, SG;Yee, D
通讯作者：
Yee, D
影响因子：
64.8
作者：
BUCKBINDER, L;TALBOTT, R;KLEY, N
通讯作者：
KLEY, N
影响因子：
8
作者：
Bourdon, JC;DeguinChambon, V;May, E
通讯作者：
May, E
影响因子：
4.8
作者：
Hong, J;Zhang, G;Rechler, MM
通讯作者：
Rechler, MM