Glioblastoma stem cell-derived exosomal miR-374b-3p promotes tumor angiogenesis and progression through inducing M2 macrophages polarization.

Glioblastoma stem cells (GSCs) reside in hypoxic periarteriolar niches of glioblastoma micro-environment, however, the crosstalk of GSCs with macrophages on regulating tumor angiogenesis and progression are not fully elucidated. GSCs-derived exosomes (GSCs-exos) are essential mediators during tumor immune-microenvironment remodeling initiated by GSCs, resulting in M2 polarization of tumor-associated macrophages (TAMs) as we reported previously. Our data disclosed aberrant upregulation of miR-374b-3p in both clinical glioblastoma specimens and human cell lines of GSCs. MiR-374b-3p level was high in GSCs-exos and can be internalized by macrophages. Mechanistically, GSCs exosomal miR-374b-3p induced M2 polarization of macrophages by downregulating phosphatase and tensin expression, thereby promoting migration and tube formation of vascular endothelial cells after coculture with M2 macrophages. Cumulatively, these data indicated that GSCs exosomal miR-374b-3p can enhance tumor angiogenesis by inducing M2 polarization of macrophages, as well as promote malignant progression of glioblastoma. Targeting exosomal miR-374b-3p may serve as a potential target against glioblastoma.

Transformed astrocytes confer temozolomide resistance on glioblastoma via delivering ALKBH7 to enhance APNG expression after educating by glioblastoma stem cells-derived exosomes.

BACKGROUND: Glioblastoma is the most malignant primary brain tumor in adults. Temozolomide (TMZ) stands for the first-line chemotherapeutic agent against glioblastoma. Nevertheless, the therapeutic efficacy of TMZ appears to be remarkably limited, because of low cytotoxic efficiency against glioblastoma. Besides, various mechanical studies and the corresponding strategies fail to enhancing TMZ curative effect in clinical practice. Our previous studies have disclosed remodeling of glial cells by GSCs, but the roles of these transformed cells on promoting TMZ resistance have never been explored. METHODS: Exosomes were extracted from GSCs culture through standard centrifugation procedures, which can activate transformation of normal human astrocytes (NHAs) totumor-associated astrocytes (TAAs) for 3 days through detect the level of TGF-ß, CD44 and tenascin-C. The secretive protein level of ALKBH7 of TAAs was determined by ELISA kit. The protein level of APNG and ALKBH7 of GBM cells were determined by Western blot. Cell-based assays of ALKBH7 and APNG triggered drug resistance were performed through flow cytometric assay, Western blotting and colony formation assay respectively. A xenograft tumor model was applied to investigate the function of ALKBH7 in vivo. Finally, the effect of the ALKBH7/APNG signaling on TMZ resistance were evaluated by functional experiments. RESULTS: Exosomes derived from GSCs can activate transformation of normal human astrocytes (NHAs)to tumor-associated astrocytes (TAAs), as well as up-regulation of ALKBH7expression in TAAs. Besides, TAAs derived ALKBH7 can regulate APNG gene expression of GBM cells. After co-culturing with TAAs for 5 days, ALKBH7 and APNG expression in GBM cells were elevated. Furthermore, Knocking-down of APNG increased the inhibitory effect of TMZ on GBM cells survival. CONCLUSION: The present study illustrated a new mechanism of glioblastoma resistance to TMZ, which based on GSCs-exo educated TAAs delivering ALKBH7 to enhance APNG expression of GBM cells, which implied that targeting on ALKBH7/APNG regulation network may provide a new strategy of enhancing TMZ therapeutic effects against glioblastoma.

Glioma stem cell-derived exosomes induce the transformation of astrocytes via the miR-3065-5p/DLG2 signaling axis.

Tumor-associated astrocytes (TAAs) in the glioblastoma microenvironment play an important role in tumor development and malignant progression initiated by glioma stem cells (GSCs). In the current study, normal human astrocytes (NHAs) were cultured and continuously treated with GSC-derived exosomes (GSC-EXOs) induction to explore the mechanism by which GSCs affect astrocyte remodeling. This study revealed that GSC-EXOs can induce the transformation of NHAs into TAAs, with relatively swollen cell bodies and multiple extended processes. In addition, high proliferation, elevated resistance to temozolomide (TMZ), and increased expression of TAA-related markers (TGF-ß, CD44, and tenascin-C) were observed in the TAAs. Furthermore, GSC-derived exosomal miR-3065-5p could be delivered to NHAs, and miR-3065-5p levels increased significantly in TAAs, as verified by miRNA expression profile sequencing and Reverse transcription polymerase chain reaction. Overexpression of miR-3065-5p also enhanced NHA proliferation, elevated resistance to TMZ, and increased the expression levels of TAA-related markers. In addition, both GSC-EXO-induced and miR-3065-5p-overexpressing NHAs promoted tumorigenesis of GSCs in vivo. Discs Large Homolog 2 (DLG2, downregulated in glioblastoma) is a direct downstream target of miR-3065-5p in TAAs, and DLG2 overexpression could partially reverse the transformation of NHAs into TAAs. Collectively, these data demonstrate that GSC-EXOs induce the transformation of NHAs into TAAs via the miR-3065-5p/DLG2 signaling axis and that TAAs can further promote the tumorigenesis of GSCs. Thus, precisely blocking the interactions between astrocytes and GSCs via exosomes may be a novel strategy to inhibit glioblastoma development, but more in-depth mechanistic studies are still needed.

Exosomal miR-6733-5p mediates cross-talk between glioblastoma stem cells and macrophages and promotes glioblastoma multiform progression synergistically.

AIM: Exosomal miRNAs derived from glioblastoma stem cells (GSCs) are important mediators of immunosuppressive microenvironment formation in glioblastoma multiform (GBM), especially in M2-like polarization of tumor-associated macrophages (TAMs). However, the exact mechanisms by which GSCs-derived exosomes (GSCs-exo) facilitate the remodeling of the immunosuppressive microenvironment of GBM have not been elucidated. METHODS: Transmission electron microscopy (TME) and nanoparticle tracking analysis (NTA) were applied to verify the existence of GSCs-derived exosomes. Sphere formation assays, flow cytometry, and tumor xenograft transplantation assays were performed to identify the exact roles of exosomal miR-6733-5p. Then, the mechanisms of miR-6733-5p and its downstream target gene regulating crosstalk between GSCs cells and M2 macrophages were further investigated. RESULTS: GSCs-derived exosomal miR-6733-5p induce macrophage M2 polarization of TAMs by positively targeting IGF2BP3 to activate the AKT signaling pathway, which further facilitates the self-renewal and stemness of GSCs. CONCLUSION: GSCs secrete miR-6733-5p-rich exosomes to induce M2-like polarization of macrophages, as well as enhance GSCs stemness and promote malignant behaviors of GBM through IGF2BP3 activated AKT pathway. Targeting GSCs exosomal miR-6733-5p may provide a potential new strategy against GBM.

Intralayer Synchronization of Multiplex Dynamical Networks via Pinning Impulsive Control.

These days, the synchronization of multiplex networks is an emerging and important research topic. Grounded framework and theory about synchronization and control on multiplex networks are yet to come. This article studies the intralayer synchronization on a multiplex network (i.e., a set of networks connected through interlayer edges), via the pinning impulsive control method. The topologies of different layers are independent of each other, and the individual dynamics of nodes in different layers are different as well. Supra-Laplacian matrices are adopted to represent the topological structures of multiplex networks. Two cases are considered according to impulsive sequences of multiplex networks: 1) pinning controllers are applied to all the layers simultaneously at the instants of a common impulse sequence and 2) pinning controllers are applied to each layer at the instants of distinct impulse sequences. Using the Lyapunov stability theory and the impulsive control theory, several intralayer synchronization criteria for multiplex networks are obtained, in terms of the supra-Laplacian matrix of network topology, self-dynamics of nodes, impulsive intervals, and the pinning control effect. Furthermore, the algorithms for implementing pinning schemes at every impulsive instant are proposed to support the obtained criteria. Finally, numerical examples are presented to demonstrate the effectiveness and correctness of the proposed schemes.

Topology Identification of Multilink Complex Dynamical Networks via Adaptive Observers Incorporating Chaotic Exosignals.

Topology identification of complex networks is an important and meaningful research direction. In recent years, the topology identification method based on adaptive synchronization has been developed rapidly. However, a critical shortcoming of this method is that inner synchronization of a network breaks the precondition of linear independence and leads to the failure of topology identification. Hence, how to identify the network topology when possible inner synchronization occurs within the network has been a challenging research issue. To solve this problem, this article proposes improved topology identification methods by regulating the original network to synchronize with an auxiliary network composed of isolated chaotic exosystems. The proposed methods do not require the sophisticated assumption of linear independence. The topology identification observers incorporating a series of isolated chaotic exosignals can accurately identify the network structure. Finally, numerical simulations show that the proposed methods are effective to identify the structure of a network even with large weights of edges and abundant connections between nodes.