Section of Oncology, Division of Cancer, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
Breast Cancer Res Treat. 2011 Jan;125(1):43-53. doi: 10.1007/s10549-010-0823-1. Epub 2010 Mar 12.
Nicastrin is an essential component of the gamma secretase (GS) enzyme complex, required for its synthesis and recognition of substrates for proteolytic cleavage. The purpose of this study was to investigate whether nicastrin has prognostic value or potential as a therapeutic target in breast cancer (BC). The suitability of nicastrin as a target in BC was assessed using BC tissue microarrays (TMAs) (n = 1050), and its biological role in vitro was evaluated in BC cell lines following gene silencing. Nicastrin blocking antibodies were developed and evaluated for their suitability as potential clinical therapeutics. TMA and cell line analysis confirmed that nicastrin expression was upregulated in BC compared to normal breast cells. In TMA patient samples, high nicastrin expression was observed in 47.5% of cases and correlated with ERα expression, patient age, and tumor grade. In pre-defined subset analysis, high nicastrin expression predicted for worse BC specific survival in the ERα -ve cohort. In vitro gene silencing of nicastrin resulted in disruption of the GS complex and a decrease in notch1 cleavage. This was sufficient to increase E-cadherin expression and its co-localization with p120 catenin at cell-cell junctions in MCF7 cells. Nicastrin silencing in invasive MDA-MB-231 cells resulted in loss of vimentin expression and a marked reduction in both cell motility and invasion; which was concomitant with the de novo formation of cell-cell junctions characterized by the colocalization of p120 catenin and F-actin. These data indicate that nicastrin can function to maintain epithelial to mesenchymal transition during BC progression. Anti-nicastrin polyclonal and monoclonal antibodies were able to decrease notch1 and vimentin expression and reduced the invasive capacity of BC cells in vitro. This supports our hypothesis that a nicastrin blocking antibody could be used to limit metastatic dissemination in invasive BC.
尼卡丁是 γ 分泌酶（GS）酶复合物的必需组成部分，对于其合成和识别蛋白水解切割的底物是必需的。本研究旨在探讨尼卡丁在乳腺癌（BC）中是否具有预后价值或作为治疗靶点的潜力。使用 BC 组织微阵列（TMA）（n = 1050）评估尼卡丁作为 BC 靶点的适宜性，并在基因沉默后评估其在 BC 细胞系中的生物学作用。开发了尼卡丁阻断抗体，并评估其作为潜在临床治疗药物的适用性。TMA 和细胞系分析证实，与正常乳腺细胞相比，BC 中尼卡丁的表达上调。在 TMA 患者样本中，47.5%的病例观察到高尼卡丁表达，且与 ERα 表达、患者年龄和肿瘤分级相关。在预定义的亚组分析中，高尼卡丁表达预示 ERα-ve 队列中 BC 特异性生存较差。体外基因沉默尼卡丁导致 GS 复合物的破坏和 notch1 切割减少。这足以增加 MCF7 细胞中 E-钙粘蛋白的表达及其与 p120 连环蛋白在细胞-细胞连接处的共定位。在侵袭性 MDA-MB-231 细胞中沉默尼卡丁导致波形蛋白表达丧失，细胞迁移和侵袭能力显著降低；同时伴有细胞-细胞连接处的新形成，其特征为 p120 连环蛋白和 F-肌动蛋白的共定位。这些数据表明，尼卡丁可以在 BC 进展过程中维持上皮-间充质转化。抗尼卡丁多克隆和单克隆抗体能够降低 notch1 和波形蛋白的表达，并降低 BC 细胞在体外的侵袭能力。这支持了我们的假设，即尼卡丁阻断抗体可用于限制侵袭性 BC 的转移扩散。
