Regulated expression of the orphan nuclear estrogen-related receptor alpha

孤儿核雌激素相关受体α的调节表达

• 批准号: 8156794
• 负责人: MICHEL BERNIER
• 金额: $ 28.71万
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8156794
• 关键词: ERR1 protein; Nuclear; Orphan

Earlier studies have described CB1R-independent actions of AM251 in wild-type and CB1R knockout mice. Here we observed a potent and coordinate induction in the expression of EGFR and its ligands by AM251 in the human PANC-1 pancreatic cancer cell line and HCT116 colon carcinoma cells. This event was associated with enhanced expression of EGFR on the cell surface with concomitant increase in EGF-induced cellular responses in AM251-treated cells. Using genetic, biochemical and pharmacological approaches, we showed that this transcriptional response was NOT related to the modulation of cannabinoid 1 receptor, but, instead, relied on AM251s role as an inverse agonist of estrogen-related receptor α (ERRα). ERRα is an orphan nuclear receptor, whose expression in tumor cells is associated with bad prognosis. Exposure to the synthetic estrogen diethylstilbestrol or the classical inverse agonist XCT790 also induced EGFR and ligands at the transcriptional level to the same extent as AM251, whereas pretreatment with the ERRα selective agonist, biochanin A, blunted AM251 actions. AM251 promoted the proteolytic degradation of ERRα protein without loss of the corresponding mRNA. Knockdown of ERRα by siRNA-based approach led to constitutive induction of EGFR and its ligands and eliminated the biological responses of AM251 and XCT790. Finally, AM251 was found to displace diethylstilbestrol prebound to the ligand-binding domain of ERRα. In summary, this study demonstrates that the CB1R inverse agonist, AM251, exerts off-target effects through binding to and destabilization of the orphan nuclear receptor ERRα in cultured human cancer cell lines. Because of the structural characteristics of AM251 and its clinical analog, rimonabant, future studies will need to be carried out in a panel of normal and cancer cell lines and in vivo models to determine the properties of these compounds as potential endocrine-disrupting chemicals and cancer-inducing agents. Work is underway to determine whether pharmacological interventions provide a viable avenue for interfering with ERRα protein stability in cellular models of various human cancer types and mouse xenograft models. Because of the newly discovered role for ERRα in adaptive energy metabolism, strategies aimed at targeting ERRα may be useful in fighting not only cancer but also metabolic diseases as well. A new investigation on the effect of AM251 on ERRα transcriptional activity will be initiated soon, focusing on histone acetylation and DNA methylation, two major epigenetic molecular mechanisms involved in activation or repression of transcription through changes in chromatin configurations. It is likely that the recruitment of nuclear co-regulatory molecules and other DNA-binding proteins to ERRα at the target gene promoter region is mediated by a mechanism involving epigenetic alterations.

早期的研究已经描述了AM 251在野生型和CB 1 R敲除小鼠中的CB 1 R独立作用。在此，我们观察到AM 251在人PANC-1胰腺癌细胞系和HCT 116结肠癌细胞中对EGFR及其配体表达的有效和协调诱导。该事件与细胞表面EGFR表达增强相关，伴随着AM 251处理细胞中EGF诱导的细胞应答增加。使用遗传，生物化学和药理学方法，我们表明这种转录反应与大麻素1受体的调节无关，而是依赖于AM 251作为雌激素相关受体（ERR）的反向激动剂的作用。ERR是一种孤儿核受体，其在肿瘤细胞中的表达与不良预后相关。暴露于合成雌激素己烯雌酚或经典的反向激动剂XCT 790也诱导EGFR和配体在转录水平上与AM 251相同的程度，而预处理与ERR选择性激动剂，鹰嘴豆芽素A，钝化AM 251的行动。AM 251促进ERR蛋白的蛋白质降解，而不损失相应的mRNA。通过基于siRNA的方法敲低ERR导致EGFR及其配体的组成型诱导，并消除了AM 251和XCT 790的生物学应答。最后，AM 251被发现取代己烯雌酚prebound的配体结合结构域的ERR。总之，本研究表明，CB 1 R反向激动剂AM 251通过与培养的人癌细胞系中孤儿核受体ERR结合并使其不稳定而发挥脱靶效应。由于AM 251及其临床类似物利莫那班的结构特征，未来的研究将需要在一组正常和癌细胞系和体内模型中进行，以确定这些化合物作为潜在内分泌干扰化学物质和癌症诱导剂的特性。 正在进行的工作是确定药物干预是否提供了一个可行的途径，干扰ERR蛋白的稳定性，在各种人类癌症类型的细胞模型和小鼠异种移植模型。由于新发现的ERR在适应性能量代谢中的作用，旨在靶向ERR的策略不仅可用于对抗癌症，还可用于对抗代谢性疾病。 关于AM 251对ERR转录活性影响的新研究即将启动，重点是组蛋白乙酰化和DNA甲基化，这两种主要的表观遗传分子机制涉及通过染色质构型的变化激活或抑制转录。核共调节分子和其他DNA结合蛋白在靶基因启动子区向ERR的募集可能由涉及表观遗传改变的机制介导。