Mechanisms of tamoxifen resistance: Increased estrogen receptor-HER2/neu cross-talk in ER/HER2-positive breast cancer
Mechanisms of tamoxifen resistance: Increased estrogen receptor-HER2/neu cross-talk in ER/HER2-positive breast cancer
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DOI：
10.1093/jnci/djh166
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发表时间：
2004-06-16
影响因子：
10.3
通讯作者：
Schiff, R
中科院分区：
文献类型：
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作者：
Shou, J;Massarweh, S;Schiff, R
背景资料：接受他莫昔芬辅助治疗的患者，其肿瘤表达高水平的HER 2/neu（HER 2）和雌激素受体（ER）共激活因子AIB 1，通常会产生他莫昔芬耐药。我们使用AIB 1和HER 2高表达的乳腺癌模型系统来研究这种耐药的可能机制。研究方法：在不存在或存在EGF受体（EGFR）酪氨酸激酶抑制剂吉非替尼的情况下，用雌激素、他莫昔芬、表皮生长因子（EGF）或调蛋白处理表达高水平AIB 1的MCF-7乳腺癌细胞和经工程改造过表达HER 2的他莫昔芬抗性衍生细胞系（MCF-7/HER 2 -18）。我们通过免疫印迹分析了信号中间体的磷酸化，报告基因构建体的ER转录活性和内源性基因产物的免疫印迹分析，通过染色质免疫沉淀（ChIP）测定的启动子组装，以及通过锚定非依赖性集落形成体外和体内裸鼠异种移植瘤的肿瘤细胞生长。结果：MCF-7/HER 2 -18肿瘤生长完全被雌激素剥夺抑制，但被他莫昔芬刺激生长。与MCF-7细胞相比，MCF-7/HER-2细胞中ER和HER 2通路之间的分子串扰增加，ER和EGFR/HER 2受体、信号分子AKT和ERK 1，2丝裂原活化蛋白激酶（MAPK）以及AIB 1本身在雌激素和他莫昔芬治疗下交叉磷酸化和活化。在MCF-7/HER 2 -18细胞中，他莫昔芬将辅激活因子复合物（ER、AIB 1、CBP、p300）募集到ER调节的pS2基因启动子，在MCF-7细胞中，将辅阻遏因子复合物（NCoR，组蛋白去乙酰化酶3）募集到ER调节的pS2基因启动子。吉非替尼预处理阻断了受体间的相互作用，与靶基因启动子上的他莫昔芬结合的ER重建了辅阻遏物复合物，消除了他莫昔芬的激动剂作用，并恢复了其在MCF-7/HER 2 -18细胞中的体外和体内抗肿瘤活性。结论：他莫昔芬在表达高水平AIB 1和HER 2的乳腺癌细胞中表现为雌激素激动剂，导致从头耐药。吉非替尼消除这种串扰和恢复他莫昔芬抗肿瘤作用的能力应该在临床上进行测试。[J Natl Cancer Inst 2004; 96：926-35]
Background: Patients receiving adjuvant tamoxifen whose tumors express high levels of both HER2/neu (HER2) and the estrogen receptor (ER) coactivator AIB1 often develop tamoxifen resistance. We used a breast cancer model system with high expression of AIB1 and HER2 to investigate the possible mechanisms underlying this resistance. Methods: MCF-7 breast cancer cells, which express high levels of AIB1, and a tamoxifen-resistant derivative cell line engineered to overexpress HER2 (MCF-7/HER2-18) were treated with estrogen, tamoxifen, epidermal growth factor (EGF), or heregulin in the absence or presence of the EGF receptor (EGFR) tyrosine kinase inhibitor gefitinib. We analyzed phosphorylation of signaling intermediates by immunoblotting, ER transcriptional activity with reporter gene constructs and immunoblot analysis of endogenous gene products, promoter assembly by chromatin immunoprecipitation (ChIP) assay, and tumor cell growth in vitro by anchorage-independent colony formation and in vivo using xenografts in nude mice. Results: MCF-7/HER2-18 tumors were completely growth inhibited by estrogen deprivation but were growth stimulated by tamoxifen. Molecular crosstalk between the ER and HER2 pathways was increased in the MCF-7/HER-2 cells compared with MCF-7 cells, with cross-phosphorylation and activation of both the ER and the EGFR/HER2 receptors, the signaling molecules AKT and ERK 1,2 mitogen-activated protein kinase (MAPK), and AIB1 itself with both estrogen and tamoxifen treatment. Tamoxifen recruited coactivator complexes (ER, AIB1, CBP, p300) to the ER-regulated pS2 gene promoter in MCF-7/ HER2-18 cells and corepressor complexes (NCoR, histone deacetylase 3) in MCF-7 cells. Gefitinib pretreatment blocked receptor cross-talk, reestablished corepressor complexes with tamoxifen-bound ER on target gene promoters, eliminated tamoxifen's agonist effects, and restored its antitumor activity both in vitro and in vivo in MCF-7/HER2-18 cells. Conclusions: Tamoxifen behaves as an estrogen agonist in breast cancer cells that express high levels of AIB1 and HER2, resulting in de novo resistance. Gefitinib's ability to eliminate this cross-talk and to restore tamoxifen's antitumor effects should be tested in the clinic. [J Natl Cancer Inst 2004; 96:926-35]