脑转移 (BrM) 是一种毁灭性的终末期神经系统并发症，高达 50% 的 HER2 乳腺癌患者会发生这种情况。了解播散性肿瘤细胞如何穿过血脑屏障 (BBB) 对于制定有效的预防策略至关重要。我们鉴定出外核苷酸酶 ENPP1 在 HER2 脑转移细胞的分泌组中特异性富集，促使我们探索其对 BBB 功能障碍和 BrM 形成的影响。我们使用体外 BBB 和体内转移前小鼠模型来评估肿瘤-分泌的 ENPP1 对脑血管通透性有影响。通过 20 kDa Cy7.5-葡聚糖外渗的实时荧光成像以及粘附物和紧密连接蛋白的免疫荧光染色来分析 BBB 完整性。在实验性脑转移模型中评估了 ENPP1 的促转移作用。原发性乳腺肿瘤系统性分泌的 ENPP1 损害了 BBB 的完整性，在 BrM 发作之前早期就失去了紧密连接蛋白和粘附连接蛋白。从机制上讲，ENPP1 通过损害胰岛素信号及其下游 AKT/GSK3β/β-catenin 通路诱导内皮细胞功能障碍。从 HER2 脑转移细胞中基因消除 ENPP1 可防止内皮细胞功能障碍并减轻转移负担，同时延长小鼠的总体生存期和无转移生存期。此外，血浆 ENPP1 水平与脑转移负担相关，并与总生存率成反比。我们证明，转移性乳腺癌细胞利用 ENPP1 信号传导进行细胞跨 BBB 的迁移和脑定植。我们的数据表明 ENPP1 是 HER2 乳腺癌不良预后和早期检测 BrM 的潜在生物标志物。© 作者 2024。由牛津大学出版社代表神经肿瘤学会出版。

Brain metastasis (BrM) is a devastating end-stage neurological complication that occurs in up to 50% of HER2+ breast cancer patients. Understanding how disseminating tumor cells manage to cross the blood-brain barrier (BBB) is essential for developing effective preventive strategies. We identified the ecto-nucleotidase ENPP1 as specifically enriched in the secretome of HER2+ brain metastatic cells, prompting us to explore its impact on BBB dysfunction and BrM formation.We used in vitro BBB and in vivo premetastatic mouse models to evaluate the effect of tumor-secreted ENPP1 on brain vascular permeability. BBB integrity was analyzed by real-time fluorescence imaging of 20 kDa Cy7.5-dextran extravasation and immunofluorescence staining of adherens and tight junction proteins. Pro-metastatic effects of ENPP1 were evaluated in an experimental brain metastatic model.Systemically secreted ENPP1 from primary breast tumors impaired the integrity of BBB with loss of tight and adherens junction proteins early before the onset of BrM. Mechanistically, ENPP1 induced endothelial cell dysfunction by impairing insulin signaling and its downstream AKT/GSK3β/β-catenin pathway. Genetic ablation of ENPP1 from HER2+ brain metastatic cells prevented endothelial cell dysfunction and reduced metastatic burden while prolonging the overall and metastasis-free survival of mice. Furthermore, plasmatic ENPP1 levels correlate with brain metastatic burden and inversely with overall survival.We demonstrated that metastatic breast cancer cells exploit the ENPP1 signaling for cell transmigration across the BBB and brain colonization. Our data implicate ENPP1 as a potential biomarker for poor prognosis and early detection of BrM in HER2+ breast cancer.© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Neuro-Oncology.