背景:人表皮生长因子受体2(HER2)在具有高转移率的人乳腺癌亚组中被扩增并成为临床靶标。涉及抗体曲妥珠单抗和曲妥珠单抗-emtansine(T-DM1)的靶向治疗极大地改善了HER2阳性(HER2+)乳腺癌患者的预后。然而,对这些靶向治疗的耐药性会发展并限制其疗效。这里,我们在HER2+乳腺癌模型中测试内吞衔接蛋白内皮素A2(EndoII)的参与,以及他们对曲妥珠单抗和T-DM1治疗的反应。
方法:用免疫组织化学方法分析EndoⅡ在人乳腺肿瘤和淋巴结转移中的表达。在HER2+癌细胞系(SK-BR-3和HCC1954)中实现了EndoII的稳定沉默,以测试EndoII对HER2水平的影响,定位和信令,细胞运动和肿瘤转移。使用实时细胞运动性和细胞毒性测定测试EndoII沉默对HER2+癌细胞对曲妥珠单抗或T-DM1治疗的应答的影响。
结果:在HER2阳性肿瘤中检测到高EndoII蛋白表达,并且在mRNA水平上与淋巴结阳性HER2+乳腺癌的总体生存率较差有关.EndoII在HER2+细胞系中的稳定沉默导致细胞表面HER2水平升高,表皮生长因子诱导的HER2内化受损,和下游效应子激酶Akt和Erk的信号传导减少。EndoII沉默还导致HER2+癌细胞在体外的迁移和侵袭减少,和小鼠尾静脉注射后肺接种受损。此外,EndoII沉默也损害了响应曲妥珠单抗的HER2内化,并导致用T-DM1处理的HER2+癌细胞的细胞毒性反应降低。
结论:我们的研究提供了EndoII在HER2+癌细胞运动性和HER2运输中的功能的新证据,这与曲妥珠单抗或T-DM1的有效治疗有关。因此,EndoII的差异表达可能与对基于曲妥珠单抗的HER2+癌症治疗的敏感性或耐药性有关.
BACKGROUND: Human epidermal growth factor receptor-2 (HER2) is amplified and a clinical target in a subset of human breast cancers with high rates of metastasis. Targeted therapies involving the antibody trastuzumab and trastuzumab-emtansine (T-DM1) have greatly improved outcomes for HER2-positive (HER2+) breast cancer patients. However, resistance to these targeted therapies can develop and limit their efficacy. Here, we test the involvement of the endocytic adaptor protein endophilin A2 (Endo II) in HER2+ breast cancer models, and their responses to treatments with trastuzumab and T-DM1.
METHODS: Endo II expression in human breast tumors and lymph node metastases were analyzed by immunohistochemistry. Stable silencing of Endo II was achieved in HER2+ cancer cell lines (SK-BR-3 and HCC1954) to test Endo II effects on HER2 levels, localization and signaling, cell motility and tumor metastasis. The effects of Endo II silencing on the responses of HER2+ cancer cells to trastuzumab or T-DM1 treatments were tested using real-time cell motility and cytotoxicity assays.
RESULTS: High Endo II protein expression was detected in HER2-positive tumors, and was linked to worse overall survival in node-positive HER2+ breast cancers at the mRNA level. Stable silencing of Endo II in HER2+ cell lines led to elevated levels of HER2 on the cell surface, impaired epidermal growth factor-induced HER2 internalization, and reduced signaling to downstream effector kinases Akt and Erk. Endo II silencing also led to decreased migration and invasion of HER2+ cancer cells in vitro, and impaired lung seeding following tail vein injection in mice. In addition, Endo II silencing also impaired HER2 internalization in response to Trastuzumab, and led to reduced cytotoxicity response in HER2+ cancer cells treated with T-DM1.
CONCLUSIONS: Our study provides novel evidence of Endo II function in HER2+ cancer cell motility and trafficking of HER2 that relates to effective treatments with trastuzumab or T-DM1. Thus, differential expression of Endo II may relate to sensitivity or resistance to trastuzumab-based therapies for HER2+ cancers.