Glioma stem-like cells (GSCs) are regarded as the sources of oncogenesis, recurrence, invasion and chemoresistance in malignant gliomas. Growing evidence suggests that the microenvironment surrounding GSCs interacts with tumor cells to influence biological behavior; however, the functional mechanisms involved are still unclear. In the present study, we investigated the modulation of GSCs triggered by fibronectin (FN), a main component of the extracellular matrix (ECM), in terms of cell adhesion, differentiation, proliferation and chemoresistance. We demonstrated that pre-coated FN prompted increased adherence by GSCs, with increased matrix metallopeptidases (MMPs)-2 and -9 expression, in a concentration-dependent manner. Decreases in sox-2 and nestin levels, and increased levels of glial fibrillary acidic protein (GFAP) and β-tubulin were also found in GSCs, indicating cell differentiation driven by FN. Further investigation revealed that FN promoted cell growth, as demonstrated by the elevation of Ki-67, with the activation of p-ERK1/2 and cyclin D1 also evident. In addition, FN suppressed p53-mediated apoptosis and upregulated P-glycoprotein expression, making GSCs more chemoresistant to alkylating agents such as carmustine. In contrast, this effect was reversed by an integrin inhibitor, cilengitide. Activation of the focal adhesion kinase/paxillin/AKT signaling pathway was involved in the modulation of GSCs by FN. Focusing on the interactions between tumor cells and the ECM may be an encouraging aspect of research on novel chemotherapeutic therapies in future.

Originating in the brain, glioblastoma (GBM) is a highly lethal and virtually incurable cancer, in large part because it readily develops resistance to treatments. While numerous studies have investigated mechanisms enabling GBM cells to evade chemotherapy-induced apoptosis, few have addressed how their surrounding extracellular matrix (ECM) acts to promote their survival. Here, we employed a biomaterial-based, 3D culture platform to investigate systematically how interactions between patient-derived GBM cells and the brain ECM promote resistance to alkylating chemotherapiesincluding temozolomide, which is used routinely in clinical practice. Scaffolds for 3D culture were fabricated from hyaluronic acid (HA)a major structural and bioactive component of the brain ECMand functionalized with the RGD (arginine-glycineaspartic acid) tripeptide to provide sites for integrin engagement. Data demonstrate that cooperative engagement of CD44, through HA, and integrin α V , through RGD, facilitates resistance to alkylating chemotherapies through co-activation of Src, which inhibited downstream expression of BCL-2 family pro-apoptotic factors. In sum, a bioengineered, 3D culture platform was used to gain new mechanistic insights into how ECM in the brain tumor microenvironment promotes resistance to chemotherapy and suggests potential avenues for the development of novel, matrix-targeted combination therapies designed to suppress chemotherapy resistance in GBM.

Chemotherapy resistance to glioblastoma (GBM) remains an obstacle that is difficult to overcome, leading to poor prognosis of GBM patients. Many previous studies have focused on resistance mechanisms intrinsic to cancer cells; the microenvironment surrounding tumor cells has been found more recently to have significant impacts on the response to chemotherapeutic agents. Extracellular matrix (ECM) proteins may confer cell adhesion-mediated drug resistance (CAMDR). Here, expression of the ECM proteins laminin, vitronectin, and fibronectin was assessed in clinical GBM tumors using immunohistochemistry. Then, patient-derived GBM cells grown in monolayers on precoated laminin, vitronectin, or fibronectin substrates were treated with cilengitide, an integrin inhibitor, and/or carmustine, an alkylating chemotherapy. Cell adhesion and viability were quantified. Transcription factor (TF) activities were assessed over time using a bioluminescent assay in which GBM cells were transduced with lentiviruses containing consensus binding sites for specific TFs linked to expression a firefly luciferase reporter. Apoptosis, mediated by p53, was analyzed by Western blotting and immunocytofluorescence. Integrin αv activation of the FAK/paxillin/AKT signaling pathway and effects on expression of the proliferative marker Ki67 were investigated. To assess effects of integrin αv activation of AKT and ERK pathways, which are typically deregulated in GBM, and expression of epidermal growth factor receptor (EGFR), which is amplified and/or mutated in many GBM tumors, shRNA knockdown was used. Laminin, vitronectin, and fibronectin were abundant in clinical GBM tumors and promoted CAMDR in GBM cells cultured on precoated substrates. Cilengitide treatment induced cell detachment, which was most pronounced for cells cultured on vitronectin. Cilengitide treatment increased cytotoxicity of carmustine, reversing CAMDR. ECM adhesion increased activity of NFκB and decreased that of p53, leading to suppression of p53-mediated apoptosis and upregulation of multidrug resistance gene 1 (MDR1; also known as ABCB1 or P-glycoprotein). Expression of Ki67 was correlative with activation of the integrin αv-mediated FAK/paxillin/AKT signaling pathway. EGFR expression increased with integrin αv knockdown GBM cells and may represent a compensatory survival mechanism. These results indicate that ECM proteins confer CAMDR through integrin αv in GBM cells.

Background: Long intergenic non-coding RNAs (lincRNAs) are associated with the progression of glioblastoma (GBM). However, how linc01094 contributes to the growth and metastatic phenotypes of GBM remains not fully studied. Methods: The expression levels of linc01094 and miR-126-5p in GBM tissues and cell lines were analyzed using qRT-PCR. Loss-of-function experiments were performed to detect the biological activity of linc01094 in GBM. Glioblastoma tumor model was constructed to explore the impact of linc01094 on GBM cell growth in vivo. Linc01094-sponged miR-126-5p was certified by luciferase reporter assay and RNA immunoprecipitation (RIP). The protein expression of miRNA target gene, dynactin subunit 4 (DCTN4) was detected using Western blotting assay. Results: Herein, we observed that the level of linc01094 was higher in GBM tissues. Silencing of linc01094 restrained the growth and invasive abilities of GBM cell. Moreover, linc01094 level was negatively associated with miR-126-5p level in GBM and linc01094 acted as a "sponge" for miR-126-5p. Reintroduction of linc01094 reversed the tumor-inhibiting effects of miR-126-5p in GBM. Conclusion: Altogether, linc01094 promoted the tumorigenesis and metastatic phenotypes of GBM cell by modulating of miR-1126-5p/DCTN4 signaling axis.