Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli 35053, Taiwan.
Department of Laboratory Medicine, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei 100225, Taiwan.
Int J Mol Sci. 2021 Feb 9;22(4):1738. doi: 10.3390/ijms22041738.
Tetraspanin CD9 is widely expressed on various cell types, such as cancer cells and mesenchymal stem cells (MSCs), and/or cell-released exosomes. It has been reported that exosomal CD9 plays an important role in intercellular communications involved in cancer cell migration and metastasis. However, reports on the effect of the CD9 of MSCs or MSC-derived exosomes on cancer cell migration are still lacking. In this study, using a transwell migration assay, we found that both dextran-coated iron oxide nanoparticles (dex-IO NPs) and ionomycin stimulated exosomal CD9 expression in human MSCs (hMSCs); however, hMSCs could not deliver them to melanoma cells to affect cell migration. Interestingly, a reduced migration of melanoma cell line was observed when the ionomycin-incubated hMSC-conditioned media but not dex-IO NP-labeled hMSC-conditioned media were in the bottom chamber. In addition, we found that dex-IO NPs decreased cellular CD9 expression in hMSCs but ionomycin increased this. Simultaneously, we found that ionomycin suppressed the expression and secretion of the chemokine CCL21 in hMSCs. The silencing of CD9 demonstrated an inhibitory role of cellular CD9 in CCL21 expression in hMSCs, suggesting that ionomycin could upregulate cellular CD9 to decrease CCL21 expression and secretion of hMSCs, which would reduce the migration of B16F10, A549 and U87MG cancer cell lines due to chemoattraction reduction of CCL21. The present study not only highlights the important role of bone marrow-derived hMSCs' CD9-mediated CCL21 regulation in cancer bone metastasis but also suggests a new distinct pharmaceutical strategy for prevention or/and therapy of cancer metastasis.
四跨膜蛋白 CD9 在多种细胞类型上广泛表达，如癌细胞和间充质干细胞（MSCs），和/或细胞释放的外泌体。据报道，外泌体 CD9 在涉及癌细胞迁移和转移的细胞间通讯中发挥重要作用。然而，关于 MSCs 或 MSC 来源的外泌体的 CD9 对癌细胞迁移的影响的报道仍然缺乏。在这项研究中，我们通过 Transwell 迁移实验发现，葡聚糖包覆的氧化铁纳米粒子（dex-IO NPs）和离子霉素均能刺激人骨髓间充质干细胞（hMSCs）中外泌体 CD9 的表达；然而，hMSCs 不能将其递送至黑色素瘤细胞以影响细胞迁移。有趣的是，当将离子霉素孵育的 hMSC 条件培养基而非 dex-IO NP 标记的 hMSC 条件培养基置于下室时，观察到黑色素瘤细胞系的迁移减少。此外，我们发现 dex-IO NPs 降低了 hMSCs 中的细胞 CD9 表达，但离子霉素增加了这种表达。同时，我们发现离子霉素抑制了 hMSCs 中趋化因子 CCL21 的表达和分泌。CD9 的沉默表明细胞 CD9 在 hMSCs 中对 CCL21 表达具有抑制作用，提示离子霉素可以上调细胞 CD9 以减少 hMSCs 中 CCL21 的表达和分泌，从而减少 CCL21 趋化作用的减少导致 B16F10、A549 和 U87MG 癌细胞系的迁移。本研究不仅强调了骨髓来源的 hMSCs 的 CD9 介导的 CCL21 调节在癌症骨转移中的重要作用，还为癌症转移的预防或/和治疗提出了一种新的独特的药物策略。
