PDF(Pubmed)
Abstract：
Aberrant estrogen receptor (ERα) signaling mediates detrimental effects of tamoxifen including drug resistance and endometrial hyperplasia. ERα36, an alternative isoform of ERα, contributes to these effects. We have demonstrated that CK2 modulates ERα expression and function in breast cancer (BCa). Here, we assess if CX-4945 (CX), a clinical stage CK2 inhibitor, can disrupt ERα66 and ERα36 signaling in BCa. Using live cell imaging, we assessed the antiproliferative effects of CX in tamoxifen-sensitive and tamoxifen-resistant BCa cells in monolayer and/or spheroid cultures. CX-induced alterations in ERα66 and ERα36 mRNA and protein expression were assessed by RT-PCR and immunoblot. Co-immunoprecipitation was performed to determine the differential interaction of ERα isoforms with HSP90 and CK2 upon CX exposure. CX caused concentration-dependent decreases in proliferation in tamoxifen-sensitive MCF-7 and tamoxifen-resistant MCF-7 Tam1 cells and significantly repressed spheroid growth in 3D models. Additionally, CX caused dramatic decreases in endogenous or exogenously expressed ERα66 and ERα36 protein. Silencing of CK2β, the regulatory subunit of CK2, resulted in destabilization and decreased proliferation, similar to CX. Co-immunoprecipitation demonstrated that ERα66/36 show CK2 dependance for interaction with molecular chaperone HSP90. Our findings show that CK2 functions regulate the protein stability of ERα66 and ERα36 through a mechanism that is dependent on CK2β subunit and HSP90 chaperone function. CX may be a component of a novel therapeutic strategy that targets both tamoxifen-sensitive and tamoxifen-resistant BCa, providing an additional tool to treat ERα-positive BCa.
摘要：
异常的雌激素受体（ERα）信号介导他莫昔芬的有害作用，包括耐药性和子宫内膜增生。ERα36，ERα的替代亚型，有助于这些影响。我们已经证明CK2在乳腺癌（BCa）中调节ERα的表达和功能。这里,我们评估CX-4945（CX），临床阶段CK2抑制剂，可以破坏BCa中的ERα66和ERα36信号传导。使用活细胞成像，我们评估了CX在单层和/或球体培养的他莫昔芬敏感和他莫昔芬耐药BCa细胞中的抗增殖作用.通过RT-PCR和免疫印迹评估CX诱导的ERα66和ERα36mRNA和蛋白表达的改变。进行免疫共沉淀以确定暴露于CX时ERα同工型与HSP90和CK2的差异相互作用。CX引起他莫昔芬敏感性MCF-7和他莫昔芬抗性MCF-7Tam1细胞增殖的浓度依赖性降低，并在3D模型中显着抑制球体生长。此外,CX引起内源性或外源性表达的ERα66和ERα36蛋白的急剧减少。沉默CK2β，CK2的调节亚基，导致不稳定和减少增殖，类似于CX。免疫共沉淀表明ERα66/36显示与分子伴侣HSP90相互作用的CK2依赖性。我们的发现表明，CK2功能通过依赖于CK2β亚基和HSP90伴侣功能的机制调节ERα66和ERα36的蛋白质稳定性。CX可能是靶向他莫昔芬敏感和他莫昔芬抗性BCa的新型治疗策略的组成部分，提供了一个额外的工具来治疗ERα阳性BCa。
