Glioblastoma progression is hindered by melatonin-primed mesenchymal stromal cells through dynamic intracellular and extracellular reorganizations

Background. Glioblastoma (GBM) is the deadliest form of brain cancer and its treatment remains an unresolved challenge. Mesenchymal stromal cells (MSCs) have been explored as vehicles for the targeted delivery of anticancer drugs due to their tumor-homing abilities. However, their clinical application is limited due to the controversial role of MSCs on carcinogenesis. This study investigates how MSCs influence tumor behavior and explores the synergistic anticancer effects of the cytoprotective melatonin (Mel). Methods. Orthotopic and subcutaneous GBM xenograft mouse models were used to assess the antitumor effect of Mel pre-treated MSCs (MSCMel). Histological, immunohistochemistry and ultrastructural analysis were conducted to identify phenotypic changes in the tumors. A set of in vitro assays, including direct and indirect co-cultures, dynamic single-cell tracking and tumorsphere migration assay, was conducted to explore the impact of MSCMel on primary and non-primary GBM cells. Transcriptome profiling was used to identify genes and pathways modulated by the synergistic therapy. Results. MSCMel delayed tumor growth in mice and increased collagen deposition. Additionally, MSCMel showed enhanced capacity to prevent GBM cell migration than untreated MSCs. Molecular analysis identified genes and pathways related to cell migration, cytoskeletal dynamics and extracellular matrix remodeling in GBM cells exposed to MSCMel, including extensive reduction of vimentin expression. Finally, a gene signature associated with the clinical outcomes of GBM patients was identified. Conclusions. Our study demonstrates that melatonin enhances the anticancer properties of MSCs, providing new insights on their interaction with GBM cells and the tumor environment. These findings offer valuable guidance for advancing MSC-based therapies in clinical practice. Overall design: U87 cells were co-cultured with MSC or melatonin-pretreated MSCs in an indirect transwell system. After co-culture, U87 cells were collected and processed for RNA-seq.

研究背景。胶质母细胞瘤（Glioblastoma, GBM）是致死性最高的脑恶性肿瘤，其临床治疗至今仍是未被攻克的难题。间充质基质细胞（Mesenchymal stromal cells, MSCs）凭借其肿瘤归巢特性，被探索作为抗肿瘤药物靶向递送的载体。然而，由于MSCs在癌变过程中作用存在争议，其临床应用受到限制。本研究旨在探究MSCs对肿瘤行为的影响，并揭示细胞保护性褪黑素（cytoprotective melatonin, Mel）的协同抗肿瘤效应。
研究方法。本研究构建原位及皮下GBM异种移植小鼠模型，以评估褪黑素预处理MSCs（MSCMel）的抗肿瘤效果。通过组织学、免疫组织化学及超微结构分析，鉴定肿瘤组织的表型变化。同时开展一系列体外实验，包括直接与间接共培养、动态单细胞追踪及肿瘤球迁移实验，探究MSCMel对原代及非原代GBM细胞的作用。采用转录组分析，筛选协同治疗调控的基因与信号通路。
研究结果。MSCMel可延缓小鼠体内肿瘤生长，并促进胶原蛋白沉积。相较于未处理的MSCs，MSCMel抑制GBM细胞迁移的能力显著增强。分子分析显示，暴露于MSCMel的GBM细胞中，与细胞迁移、细胞骨架动态及细胞外基质重塑相关的基因和通路发生显著调控，其中波形蛋白（vimentin）的表达水平大幅下调。最后，本研究鉴定出与GBM患者临床结局相关的基因特征。
研究结论。本研究证实，褪黑素可增强MSCs的抗肿瘤特性，为阐明MSCs与GBM细胞及肿瘤微环境的相互作用提供了新视角。上述研究结果为推动基于MSCs的肿瘤治疗临床转化提供了重要参考。
实验整体设计：将U87细胞与MSCs或褪黑素预处理的MSCs置于间接Transwell共培养体系中进行共培养。共培养结束后，收集U87细胞并开展RNA测序（RNA-seq）分析。