Single CpG site methylation controls estrogen receptor gene transcription and correlates with hormone therapy resistance
Single CpG site methylation controls estrogen receptor gene transcription and correlates with hormone therapy resistance
复制标题
DOI：
10.1016/j.jsbmb.2017.04.001
复制
发表时间：
2017-07-01
影响因子：
4.1
通讯作者：
Hayashi, Shin-ichi
中科院分区：
文献类型：
--
作者：
Tsuboi, Kouki;Nagatomo, Takamasa;Hayashi, Shin-ichi
激素治疗是雌激素受体α阳性乳腺癌患者最有效的治疗方法。然而，尽管在某些情况下在治疗过程中发生耐药性，并且通常反映了雌激素受体α状态的改变，但雌激素受体α表达的变化与治疗耐药性之间的关系尚不清楚。在这项研究中，我们确定了一种机制，改变雌激素受体α表达在疾病进展和获得性激素治疗耐药性芳香化酶的乳腺癌细胞系。随后，我们研究了雌激素受体α启动子的启动子转换和DNA甲基化状态，发现在耐药细胞中单个CpG位点（CpG 4）的甲基化发生了显著变化。此外，荧光素酶报告基因测定显示该甲基化CpG位点的转录活性降低。该CpG区域在物种间也是完全保守的，这表明它作为甲基化敏感的Ets-2转录因子结合位点，使用染色质免疫沉淀试验证实。在雌激素受体α阳性肿瘤中，CpG 4甲基化水平与雌激素受体α表达状态呈负相关，表明单个CpG位点在调节雌激素受体α转录中起重要作用。
Hormone therapy is the most effective treatment for patients with estrogen receptor alpha-positive breast cancers. However, although resistance occurs during treatment in some cases and often reflects changed estrogen receptor alpha status, the relationship between changes in estrogen receptor a expression and resistance to therapy are poorly understood. In this study, we identified a mechanism for altered estrogen receptor alpha expression during disease progression and acquired hormone therapy resistance in aromatase inhibitor-resistant breast cancer cell lines. Subsequently, we investigated promoter switching and DNA methylation status of the estrogen receptor alpha promoter, and found marked changes of methylation at a single CpG site (CpG4) in resistant cells. In addition, luciferase reporter assays showed reduced transcriptional activity from this methylated CpG site. This CpG region was also completely conserved among species, suggesting that it acts as a methylation-sensitive Ets-2 transcription factor binding site, as confirmed using chromatin immunoprecipitation assays. In estrogen receptor alpha-positive tumors, CpG4 methylation levels were inversely correlated with estrogen receptor alpha expression status, suggesting that single CpG site plays an important role in the regulation of estrogen receptor alpha transcription.