Methylation-mediated regulation of the glutathione S-transferase P1 gene in human breast cancer cells
Methylation-mediated regulation of the glutathione S-transferase P1 gene in human breast cancer cells
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DOI：
10.1016/s0378-1119(98)00021-3
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发表时间：
1998-03-27
期刊：
影响因子：
3.5
通讯作者：
Morrow, CS
中科院分区：
文献类型：
--
作者：
Jhaveri, MS;Morrow, CS
了解乳腺癌细胞中调节人pi类GST（GSTP 1）基因表达的机制对乳腺癌生物学的研究特别重要。在培养的人乳腺癌细胞系中，GST 1仅在雌激素受体阴性（ER-）细胞中表达，但在受体阳性（ER+）细胞中检测不到。在此之前，我们研究了瞬时转染GSTP 1启动子的活性，在体外GSTP 1启动子-DNA相互作用，和GSTP 1 mRNA的稳定性。这些研究表明，瞬时转染GSTP 1启动子元件和GSTP 1 mRNA的稳定性只能部分解释内源性GSTP 1的细胞系特异性表达。在本研究中，我们研究了GST 1 CpG岛的甲基化状态是否在GST 1调控中起重要作用。Southern印迹分析显示，GSTP 1 CpG岛在ER+、GSTP 1非表达细胞系中高甲基化，而在ER-、GSTP 1表达细胞系中甲基化不足。RT-PCR、北方印迹和Western印迹分析表明，经5-氮杂-2 '-脱氧胞苷处理后，GST P1 CpG岛部分去甲基化，导致ER+细胞系中GST P1基因的重新表达。我们的数据有力地表明，启动子的甲基化状态显着有助于GSTP 1在ER-和ER+乳腺癌细胞系中表达的水平。(C)1998年Elsevier Science B.V.
Understanding the mechanisms that regulate the human pi class GST (GSTP1) gene expression in breast cancer cells is of particular importance to the study of breast cancer biology. In cultured human breast cancer cell lines, GSTP1 is exclusively expressed in estrogen receptor-negative (ER-) cells but is undetectable in receptor-positive (ER+) cells. Previously, we examined transiently transfected GSTP1 promoter activities, in vitro GSTP1 promoter-DNA interactions, and GSTP1 mRNA stability. These studies indicated that transiently transfected GSTP1 promoter elements and GSTP1 mRNA stability could only partially explain cell line-specific expression of endogenous GSTP1. In the present study, we examined whether the methylation status of the GSTP1 CpG island plays an important role in GSTP1 regulation. Southern blot analysis revealed that the GSTP1 CpG island is hypermethlyated in ER+, GSTP1 non-expressing cell lines but is undermethylated in ER-, GSTP1 expressing cell lines. Moreover, partial demethylation of the GSTP1 CpG island by treatment with 5-aza-2'-deoxycytidine resulted in de novo gene expression in ER+ cell lines, as detected by RT-PCR, Northern blot and Western blot analyses. Our data strongly indicate that methylation status of the promoter contributes significantly to the levels of GSTP1 expressed in ER-and ER+ breast cancer cell lines. (C) 1998 Elsevier Science B.V.