👤 Borhane Annabi

Glioblastoma (GBM), a rare, highly aggressive and chemoresistant brain cancer, exhibits profound metabolic plasticity that relies, in part, on aberrant transforming growth factor-β (TGF-β) signaling. Such plasticity was recently associated with TGF-β-regulated apoptosis and autophagy. Here, we questioned whether TGF-β-regulated apoptotic/autophagic phenotypes are recapitulated in a preclinical in vitro 3D spheroid culture model of human U87 GBM-derived cells, and how metabolic alterations affect such phenotypes. 3D U87 spheroids were cultured using the hanging drop method. Western blotting was used to assess protein expression, while RT-qPCR was used to assess gene expression levels. 3D spheroids exhibited decreased AKT phosphorylation, and increased TGF-β, fibronectin, and Smad2 phosphorylation, indicative of both cell death signaling and epithelial-mesenchymal transition molecular signatures. 2-Deoxy- 3D spheroids require ATP and a TGF-β/TGF-βR1 autocrine signaling axis to recapitulate the apoptosis/autophagy phenotypes. Combining glycolysis inhibition with TGF-β signaling inhibition could offer a promising therapeutic strategy for this rare and lethal brain cancer. Show less

During obesity, the excessive accumulation of fat in tissue promotes dysregulated hormonal and cytokine homeostasis that triggers chronic inflammation, which is, in part, associated with an increased incidence of some cancers. This protumoral inflammatory environment is further exacerbated through the secretome of mature adipocytes, which promotes tumor angiogenesis. Emerging studies suggest that human adipocyte-derived mesenchymal stromal/stem cells (ADMSCs) may contribute to a complementary process supporting local angiogenesis termed vasculogenic mimicry (VM). The molecular mechanisms linking ADMSCs to VM and inflammation remain poorly understood. ADMSC 3D capillary-like structures were generated upon seeding on Cultrex. Structure analysis was performed using WIMASIS. Total RNA was extracted using TRIzol and RT-qPCR was performed to assess gene expression or screen RT Our findings revealed that in vitro priming of ADMSCs with Cultrex led to the formation of 3D capillary-like structures and the acquisition of an inflammatory molecular signature. VM-derived ADMSCs share a common proinflammatory molecular signature similar to that induced in 2D ADMSC monolayers by tumor necrosis factor (TNF)-alpha and are characterized by upregulated expression of COX2, CCL2, CCL5, CXCL5, CXCL8, IL-6, SNAI1, and MMP9. Interestingly, pharmacological inhibition or gene silencing of the JAK2/STAT3 signaling pathway reduced chemotactic cell migration, in vitro VM and the expression of proinflammatory and invasive biomarkers. Overall, we provide novel evidence that inhibiting JAK2/STAT3-regulated VM can also alter the acquisition of a proinflammatory signature and prevent the contribution of ADMSCs to alternative tumor neovascularization processes. Show less

Mesenchymal stromal/stem cells (MSC) play a crucial role in promoting neovascularization, which is essential for wound healing. They are commonly utilized as an autologous source of progenitor cells in various stem cell-based therapies. However, incomplete MSC differentiation towards a vascular endothelial cell phenotype questions their involvement in an alternative process to angiogenesis, namely vasculogenic mimicry (VM), and the signal transducing events that regulate their in vitro priming into capillary-like structures. Here, human MSC were primed on top of Cultrex matrix to recapitulate an in vitro phenotype of VM. Total RNA was extracted, and differential gene expression assessed through RNA-Seq analysis and RT-qPCR. Transient gene silencing was achieved using specific siRNA. AG490, Tofacitinib, and PP2 pharmacological effects on VM structures were analyzed using the Wimasis software. In vitro VM occurred within 4 h and was prevented by the JAK/STAT3 inhibitors AG490 and Tofacitinib, as well as by the Src inhibitor PP2. RNA-Seq highlighted STAT3 as a signaling hub contributing to VM when transcripts from capillary-like structures were compared to those from cell monolayers. Concomitant increases in IL6, IL1b, CSF1, CSF2, STAT3, FOXC2, RPSA, FN1, and SNAI1 transcript levels suggest the acquisition of a combined angiogenic, inflammatory and epithelial-to-mesenchymal transition phenotype in VM cultures. Increases in STAT3, FOXC2, RPSA, Fibronectin, and Snail protein expression were confirmed during VM. STAT3 and RPSA gene silencing abrogated in vitro VM. In conclusion, in vitro priming of MSC into VM structures requires Src/JAK/STAT3 signaling. This molecular evidence indicates that a clinically viable MSC-mediated pseudo-vasculature process could temporarily support grafts through VM, allowing time for the host vasculature to infiltrate and remodel the injured tissues. Show less

Glioblastoma (GBM) is a highly angiogenic malignancy of the central nervous system that resists standard antiangiogenic therapy, in part because of an alternative process to angiogenesis termed vasculogenic mimicry. Intricately linked to GBM, dysregulation of the Hippo signaling pathway leads to overexpression of YAP/TEAD and several downstream effectors involved in therapy resistance. Little is known about whether vasculogenic mimicry and the Hippo pathway intersect in the GBM chemoresistance phenotype. This study seeks to investigate the expression patterns of Hippo pathway regulators within clinically annotated GBM samples, examining their involvement in vitro regarding vasculogenic mimicry. In addition, it aims to assess the potential for pharmacological targeting of this pathway. In-silico analysis of the Hippo signaling members YAP1 , TEAD1 , AXL , NF2 , CTGF , and CYR61 transcript levels in low-grade GBM and GBM tumor tissues was done by Gene Expression Profiling Interactive Analysis. Gene expression was analyzed by real-time quantitative PCR from human U87, U118, U138, and U251 brain cancer cell lines and in clinically annotated brain tumor cDNA arrays. Transient gene silencing was performed with specific small interfering RNA. Vasculogenic mimicry was assessed using a Cultrex matrix, and three-dimensional capillary-like structures were analyzed with Wimasis. CYR61 and CTGF transcript levels were elevated in GBM tissues and were further induced when in-vitro vasculogenic mimicry was assessed. Silencing of CYR61 and CTGF , or treatment with a small-molecule TEAD inhibitor LM98 derived from flufenamic acid, inhibited vasculogenic mimicry. Silencing of SNAI1 and FOXC2 also altered vasculogenic mimicry and reduced CYR61 / CTGF levels. Pharmacological targeting of the Hippo pathway inhibits in-vitro vasculogenic mimicry. Unraveling the connections between the Hippo pathway and vasculogenic mimicry may pave the way for innovative therapeutic strategies. Show less

Epithelial-to-mesenchymal transition (EMT) recapitulates metastasis and can be induced in vitro through transforming growth factor (TGF)-β signaling. A role for MMP activity in glioblastoma multiforme has been ascribed to EMT, but the molecular crosstalk between TGF-β signaling and membrane type 1 MMP (MT1-MMP) remains poorly understood. Here, the expression of common EMT biomarkers, induced through TGF-β and the MT1-MMP inducer concanavalin A (ConA), was explored using RNA-seq analysis and differential gene arrays in human U87 glioblastoma cells. TGF-β triggered SNAIL and fibronectin expressions in 2D-adherent and 3D-spheroid U87 glioblastoma cell models. Those inductions were antagonized by the TGF-β receptor kinase inhibitor galunisertib, the JAK/STAT inhibitors AG490 and tofacitinib, and by the diet-derived epigallocatechin gallate (EGCG). Transient gene silencing of MT1-MMP prevented the induction of SNAIL by ConA and abrogated TGF-β-induced cell chemotaxis. Moreover, ConA induced STAT3 and Src phosphorylation, suggesting these pathways to be involved in the MT1-MMP-mediated signaling axis that led to SNAIL induction. Our findings highlight a new signaling axis linking MT1-MMP to TGF-β-mediated EMT-like induction in glioblastoma cells, the process of which can be prevented by the diet-derived EGCG. Show less