晚期乳腺癌以及导致癌细胞存活的无效治疗可能导致这些恶性细胞从原发肿瘤扩散到远处器官。最近的研究表明，microRNA 200c (miR-200c) 可以阻碍侵袭-转移级联的某些步骤。然而，目前尚不清楚仅 miR-200c 表达是否足以阻止乳腺癌细胞转移形成。因此，我们进行了异种移植小鼠实验，在 MDA-MB 231 细胞中诱导 miR-200c 表达。对肺、肝、脑和脾等多种器官转移部位的离体分析显示，表达 miR-200c 的肿瘤小鼠的转移负担显着降低。转移形成的基本先决条件是癌细胞的运动及其迁移。因此，我们利用具有转基因 miR-200c 表达的 MDA-MB 231 和 MCF7 细胞系统分析了 miR-200c 对体外集体和单细胞迁移的影响。对集体细胞迁移的分析揭示了 miR-200c 表达改变的细胞的汇合依赖性运动。此外，划痕实验显示 miR-200c 阴性细胞更容易离开细胞簇。使用 Transwell 实验验证了集体和单细胞迁移的中间阶段，结果显示 miR-200c 阳性细胞的迁移减少。最后，为了测量单细胞水平的迁移，对哑铃形微图案进行了一种新的测定，结果表明 miR-200c 关键地决定了有限的细胞运动。所有这些结果表明，miR-200c 的单独表达会阻碍体内转移形成和体外迁移，并强调 miR-200c 作为乳腺癌的转移抑制因子。© 2024 作者。约翰·威利出版的《分子肿瘤学》

Advanced breast cancer, as well as ineffective treatments leading to surviving cancer cells, can result in the dissemination of these malignant cells from the primary tumor to distant organs. Recent research has shown that microRNA 200c (miR-200c) can hamper certain steps of the invasion-metastasis cascade. However, it is still unclear whether miR-200c expression alone is sufficient to prevent breast cancer cells from metastasis formation. Hence, we performed a xenograft mouse experiment with inducible miR-200c expression in MDA-MB 231 cells. The ex vivo analysis of metastatic sites in a multitude of organs, including lung, liver, brain, and spleen, revealed a dramatically reduced metastatic burden in mice with miR-200c-expressing tumors. A fundamental prerequisite for metastasis formation is the motility of cancer cells and, therefore, their migration. Consequently, we analyzed the effect of miR-200c on collective- and single-cell migration in vitro, utilizing MDA-MB 231 and MCF7 cell systems with genetically modified miR-200c expression. Analysis of collective-cell migration revealed confluence-dependent motility of cells with altered miR-200c expression. Additionally, scratch assays showed an enhanced predisposition of miR-200c-negative cells to leave cell clusters. The in-between stage of collective- and single-cell migration was validated using transwell assays, which showed reduced migration of miR-200c-positive cells. Finally, to measure migration at the single-cell level, a novel assay on dumbbell-shaped micropatterns was performed, which revealed that miR-200c critically determines confined cell motility. All of these results demonstrate that sole expression of miR-200c impedes metastasis formation in vivo and migration in vitro and highlights miR-200c as a metastasis suppressor in breast cancer.© 2024 The Author(s). Molecular Oncology published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.