Karakas Bahriye, Aka Yeliz, Giray Asli, Temel Sehime Gulsun, Acikbas Ufuk, Basaga Huveyda, Gul Ozgur, Kutuk Ozgur
Sabanci University, Molecular Biology, Genetics and Bioengineering Program, Istanbul, Turkey.
Baskent University School of Medicine, Dept. of Immunology, Adana Dr. Turgut Noyan Medical and Research Center, Adana, Turkey.
Cell Death Discov. 2021 Jul 22;7(1):189. doi: 10.1038/s41420-021-00573-2.
Breast cancer is the most common cancer with a high rate of mortality and morbidity among women worldwide. Estrogen receptor status is an important prognostic factor and endocrine therapy is the choice of first-line treatment in ER-positive breast cancer. However, most tumors develop resistance to endocrine therapy. Here we demonstrate that BH3 profiling technology, in particular, dynamic BH3 profiling can predict the response to endocrine therapy agents as well as the development of acquired resistance in breast cancer cells independent of estrogen receptor status. Immunofluorescence analysis and subcellular fractionation experiments revealed distinct ER-α and ER-β subcellular localization patterns in breast cancer cells, including mitochondrial localization of both receptor subtypes. shRNA-mediated depletion of ER-β in breast cancer cells led to resistance to endocrine therapy agents and selective reconstitution of ER-β in mitochondria restored sensitivity. Notably, mitochondria-targeted ER-α did not restore sensitivity, even conferred further resistance to endocrine therapy agents. In addition, expressing mitochondria-targeted ER-β in breast cancer cells resulted in decreased mitochondrial respiration alongside increased total ROS and mitochondrial superoxide production. Furthermore, our data demonstrated that mitochondrial ER-β can be successfully targeted by the selective ER-β agonist Erteberel. Thus, our findings provide novel findings on mitochondrial estrogen signaling in breast cancer cells and suggest the implementation of the dynamic BH3 technique as a tool to predict acquired endocrine therapy resistance.
乳腺癌是全球女性中最常见的癌症，其死亡率和发病率都很高。雌激素受体状态是一个重要的预后因素，内分泌治疗是雌激素受体阳性乳腺癌一线治疗的首选。然而，大多数肿瘤会对内分泌治疗产生耐药性。在此我们证明，BH3分析技术，尤其是动态BH3分析，能够预测乳腺癌细胞对内分泌治疗药物的反应以及获得性耐药的发生，且与雌激素受体状态无关。免疫荧光分析和亚细胞分级实验揭示了乳腺癌细胞中雌激素受体α（ER-α）和雌激素受体β（ER-β）不同的亚细胞定位模式，包括两种受体亚型的线粒体定位。短发夹RNA（shRNA）介导的乳腺癌细胞中ER-β缺失导致对内分泌治疗药物产生耐药性，而线粒体中ER-β的选择性重建恢复了敏感性。值得注意的是，靶向线粒体的ER-α并不能恢复敏感性，甚至会使细胞对内分泌治疗药物产生进一步的耐药性。此外，在乳腺癌细胞中表达靶向线粒体的ER-β会导致线粒体呼吸作用减弱，同时总活性氧（ROS）和线粒体超氧化物生成增加。此外，我们的数据表明，线粒体ER-β可被选择性ER-β激动剂Erteberel成功靶向。因此，我们的研究结果为乳腺癌细胞中线粒体雌激素信号传导提供了新的发现，并建议将动态BH3技术作为一种预测获得性内分泌治疗耐药性的工具加以应用。
