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Epigenetic silencing of SALL2 confers tamoxifen resistance in breast cancer.
EMBO Molecular Medicine ( IF 9.0 ) Pub Date : 2019-10-28 , DOI: 10.15252/emmm.201910638
Liping Ye 1 , Chuyong Lin 1 , Xi Wang 1 , Qiji Li 2 , Yue Li 1 , Meng Wang 1 , Zekun Zhao 3 , Xianqiu Wu 4 , Dongni Shi 1 , Yunyun Xiao 1 , Liangliang Ren 5 , Yunting Jian 1 , Meisongzhu Yang 5, 6 , Ruizhang Ou 7 , Guangzheng Deng 1 , Ying Ouyang 1 , Xiangfu Chen 1 , Jun Li 5 , Libing Song 1
Affiliation  

Resistance to tamoxifen is a clinically major challenge in breast cancer treatment. Although downregulation of estrogen receptor-alpha (ERα) is the dominant mechanism of tamoxifen resistance, the reason for ERα decrease during tamoxifen therapy remains elusive. Herein, we reported that Spalt-like transcription factor 2 (SALL2) expression was significantly reduced during tamoxifen therapy through transcription profiling analysis of 9 paired primary pre-tamoxifen-treated and relapsed tamoxifen-resistant breast cancer tissues. SALL2 transcriptionally upregulated ESR1 and PTEN through directly binding to the DNA promoters. By contrast, silencing SALL2 induced downregulation of ERα and PTEN and activated the Akt/mTOR signaling, resulting in estrogen-independent growth and tamoxifen resistance in ERα-positive breast cancer. Furthermore, hypermethylation of SALL2 promoter was found in tamoxifen-resistant breast cancer. Importantly, in vivo experiments showed that DNA methyltransferase inhibitor-mediated SALL2 restoration resensitized tamoxifen-resistant breast cancer to tamoxifen therapy. These findings shed light on the mechanism of SALL2 in regulation of ER and represent a potential clinical signature that can be used to categorize breast cancer patients who may benefit from co-therapy with tamoxifen and DNMT inhibitor.

中文翻译:

SALL2 的表观遗传沉默赋予了乳腺癌对他莫昔芬的耐药性。

对他莫昔芬的耐药性是乳腺癌治疗的临床主要挑战。尽管雌激素受体-α (ERα) 的下调是他莫昔芬耐药的主要机制,但在他莫昔芬治疗期间 ERα 降低的原因仍然难以捉摸。在这里,我们通过对 9 对原发性三苯氧胺前治疗和复发的三苯氧胺耐药乳腺癌组织的转录谱分析,报道了 Spalt 样转录因子 2 (SALL2) 的表达在三苯氧胺治疗期间显着降低。SALL2 通过直接结合 DNA 启动子转录上调 ESR1 和 PTEN。相比之下,沉默 SALL2 诱导 ERα 和 PTEN 的下调并激活 Akt/mTOR 信号传导,导致 ERα 阳性乳腺癌的雌激素非依赖性生长和他莫昔芬耐药。此外,在对他莫昔芬耐药的乳腺癌中发现了 SALL2 启动子的高甲基化。重要的是,体内实验表明 DNA 甲基转移酶抑制剂介导的 SALL2 恢复使对他莫昔芬耐药的乳腺癌对他莫昔芬治疗重新敏感。这些发现揭示了 SALL2 调节 ER 的机制,并代表了一种潜在的临床特征,可用于对可能受益于他莫昔芬和 DNMT 抑制剂联合治疗的乳腺癌患者进行分类。
更新日期:2019-12-06
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