Biology subjects

Varela, M. L.

Publications and source records attributed to Varela, M. L..

4 recordsLinked to original sources

bioRxiv2025

Gliomas organize as liquid crystals: three-dimensional nematic order, disclinations and quasi-long-range order

Active nematic liquid crystals are the main structural phase of gliomas, promoting collective migration and aggression. We establish the existence of nematic order and topological defect lines and loops in 3D in vivo mouse and human glioma brain tumors. As predicted by theory, sections through the disclination lines in 3D appear as {+/-}1/2 topological defects in 2D. In 3D, these defects either persist along disclination lines or twist as they interconvert from -1/2 to +1/2. Cell alignment exhibits quasi-long-range order, spreading throughout the tumor over distances between 300-3000 m. In vitro -1/2 and +1/2 defects display changes in apoptosis levels, suggesting topological defects regulate glioma cell density. The large scale order of gliomas correlates with tumors aggressive behavior. The organization of gliomas as active nematic liquid crystals provides a novel physical foundation of complex solid tumors; their deconstruction signposts potential treatments for deadly cancers.

biophysics↗

bioRxiv2023

Modeling Glioma Oncostreams In Vitro: Spatiotemporal Dynamics of their Formation, Stability, and Disassembly

Glioblastoma (GBM), known for its invasive nature, remains a challenge in clinical oncology due to its poor prognosis. Only 5% of patients live past 2 years. The extensive intra-tumoral heterogeneity, combined with aggressive infiltration into surrounding healthy brain tissue limits complete resection and reduces the efficiency of therapeutic interventions. In previous studies using ex-vivo 3D explants and in-vivo intravital imaging, we discovered the existence of oncostreams. Oncostreams are accumulations of nematically aligned elongated spindle-like cells constituted by both tumor and non-tumor cells. We observed a direct correlation between the density of oncostreams and glioma aggressiveness, in genetically engineered mouse glioma models, in high-grade human gliomas, and especially in gliosarcomas. Oncostreams play a pivotal role in the intra-tumoral distribution of both tumoral and non-tumoral cells, potentially facilitating collective invasion of neighboring healthy brain tissue. We further identified a unique molecular signature intrinsic to oncostreams, with a prominent overexpression of COL1A1, MMP9, ADAMts2, and ACTA2 - pivotal genes influencing gliomas mesenchymal transformation and potential determinants of tumor malignancy. COL1A1 inhibition in genetic mouse gliomas resulted in the elimination of oncostreams and induced significant changes in the tumor microenvironment, a reduction in mesenchymal-associated gene expression, and prolonged animal survival. Based on this foundation, we endeavored to model glioma oncostreams in vitro, evaluating the potential of various pharmacologic agents on the formation and organization of oncostreams. Using an optimized workflow, oncostreams were established using GFP+ NPA cells (NRAs\shP53\shATRX) derived from a genetically engineered mouse model utilizing the Sleeping Beauty transposon system. In-depth global and localized statistical analysis employing Julia programming and R Studio based in-house scripts provided insights into the behavior and organization of glioma cells. Our in vitro model led us to probe the impact of factors like cell density, cell morphology, collagen coating, exposure to neurotransmitter agonists, and changes in calcium levels. We also explored interventions targeting specific cytoskeleton structures like non-muscle myosin II B and C, myosin, actomyosin, and microtubules on oncostream formation and organization. In conclusion, our data provide novel information on patterns of glioma migration, which will inform mechanisms of glioma collective invasion in vivo. Through quantitative analysis of these pathologically aggressive and invasive structures, we highlight the importance of potential anti-invasion targets in improving outcomes for GBM patients. Integrating anti-invasive molecules with conventional treatments could significantly enhance clinical benefits. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=195 HEIGHT=200 SRC="FIGDIR/small/571722v1_ufig1.gif" ALT="Figure 1"> View larger version (95K): org.highwire.dtl.DTLVardef@31a40corg.highwire.dtl.DTLVardef@1093c09org.highwire.dtl.DTLVardef@1449e7corg.highwire.dtl.DTLVardef@10892_HPS_FORMAT_FIGEXP M_FIG Dynamics of oncostream structure and cellular motility modulation. This graphical abstract represents the intricacies of the oncostream structure, a proposed model for the collective migration of cancer cells. The central diagram illustrates the oncostream structure, delineated by various treatment conditions radiating outward. Each segment displays a fluorescent micrograph showing the effect of specific inhibitors and compounds on cellular oncostream structure. The array of compounds, including TC-I-15 (21 integrin inhibitor), Collagenase, p-nitro Blebbistatin, Cytochalasin-D, BAPTA-AM, Histamine, Glutamate, 4-Hydroxy acetophenone (4-HAP), Rho-Inhibitor, and Rho-Activator I, are marked on each corresponding segment. Quantitative measures of cellular migration speed, expressed in micrometers per hour (m/h) are noted for each treatment. Notably, the top half of the diagram reveals the oncostreams sensitivity to pharmacological drug treatments, whereas the bottom half shows resistance to these treated conditions. This representation emphasizes the selective effects of pharmacological agents on cancer cell motility within the oncostream framework. C_FIG

cancer biology↗

bioRxiv2022

Zinc Finger MYND-Type Containing 8 (ZMYND8) is epigenetically regulated in mutant Isocitrate Dehydrogenase 1 (IDH1) glioma to promote radioresistance

Mutant isocitrate dehydrogenase 1 (mIDH1) alters the epigenetic regulation of chromatin, leading to a hypermethylation phenotype in adult glioma. Establishment of glioma-specific methylation patterns by mIDH1 reprogramming drives oncogenic features of cancer metabolism, stemness and therapeutic resistance. This work focuses on identifying gene targets epigenetically dysregulated by mIDH1. Treatment of glioma cells with mIDH1 specific inhibitor AGI-5198, upregulated gene networks involved in replication stress. Specifically, we found that the expression of ZMYND8, a regulator of DNA damage response was decreased in three patient-derived glioma cell cultures (GCC) after treatment with AGI-5198. ZMYND8 functions as a chromatin reader to modulate enhancer activity and recruit DNA repair machinery. Knockdown of ZMYND8 expression sensitized mIDH1 GCCs to radiotherapy marked by decreased cellular viability. Following IR, mIDH1 glioma cells with ZMYND8 knockout (KO) exhibit significant phosphorylation of ATM and sustained {gamma}H2AX activation. ZMYND8 KO mIDH1 GCCs were further responsive to IR when treated with either BRD4 or HDAC inhibitors. The accumulation of DNA damage in ZMYND8 KO mIDH1 GCCs promoted the phosphorylation of cell cycle checkpoint proteins Chk1 and Chk2. In addition, the recruitment of ZMYND8 to sites of DNA damage has been shown to be PARP- dependent. PARP inhibition further enhanced the efficacy of radiotherapy in ZMYND8 KO mIDH1 glioma cells. These findings indicate the impact of ZMYND8 in the maintenance of genomic integrity and repair of IR-induced DNA damage in mIDH1 glioma. Translational RelevanceOur understanding of radioresistance mechanisms in patient-derived glioma cell cultures (GCC) that endogenously express mIDH1-R132H are limited. We have uncovered a novel gene target Zinc Finger MYND-Type Containing 8 (ZMYND8) that is downregulated following treatment of human mIDH1 GCCs with mIDH1 specific inhibitors. We demonstrate that suppression of ZMYND8 expression by shRNA knockdown or genetic knockout reduces the cellular viability of mIDH1 GCCs to ionizing radiation (IR). Our findings reveal an epigenetic vulnerability of mIDH1 GCCs to ZMYND8 knockout (KO) which results in impaired resolution of IR-induced DNA damage and induction of cell cycle arrest. Additionally, ZMYND8 KO mIDH1 GCCs display increased radiosensitivity to inhibition of epigenetic regulators BRD4, HDAC, and PARP which could be mediated by enhanced replicative stress.

cancer biology↗

bioRxiv2021

Systemic delivery of a CXCR4-CXCL12 signaling inhibitor encapsulated in synthetic protein nanoparticles for glioma immunotherapy

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor, with poor prognosis. Major obstacles hampering effective therapeutic response in GBM are tumor heterogeneity, high infiltration of immunosuppressive myeloid cells, and the presence of the blood-brain barrier. The C-X-C Motif Chemokine Ligand 12/ C-X-C Motif Chemokine Receptor 4 (CXCL12/ CXCR4) signaling pathway is implicated in GBM invasion and cell cycle progression. While the CXCR4 antagonists (AMD3100) has a potential anti-GBM effects, its poor pharmacokinetic and systemic toxicity had precluded its clinical application. Moreover, the role of CXCL12/ CXCR4 signaling pathway in anti-GBM immunity, particularly in GBM-mediated immunosuppression has not been elucidated. Here, we developed a synthetic protein nanoparticle (SPNPs) coated with the cell-penetrating peptide iRGD (AMD3100 SPNPs) to target the CXCR4/CXCL12 signaling axis in GBM. We showed that AMD3100 SPNPs effectively blocked CXCR4 signaling in mouse and human GBM cells in vitro as well as in GBM model in vivo. This results in inhibition of GBM proliferation and induction of immunogenic tumor cell death (ICD) leading to inhibition of GBM progression. Our data also demonstrate that blocking CXCR4 sensitizes GBM cells to radiation, eliciting enhanced release of ICD ligands. Combining AMD3100 SPNPs with radiotherapy inhibited GBM progression and led to long-term survival; with 60% of mice remaining tumor-free. This was accompanied by an anti-GBM immune response and sustained immunological memory that prevented tumor recurrence without further treatment. Finally, we showed that systemic delivery of AMD3100 SPNPs decreased the infiltration of CXCR4+ monocytic myeloid-derived suppressor cells to the tumor microenvironment. With the potent ICD induction and reprogrammed immune microenvironment, this strategy has significant potential for future clinical translation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/457953v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@17c9377org.highwire.dtl.DTLVardef@1b5a4dcorg.highwire.dtl.DTLVardef@5aa4eaorg.highwire.dtl.DTLVardef@1011a86_HPS_FORMAT_FIGEXP M_FIG Immunological mechanism targeting Glioblastoma (GBM) upon blocking CXCR4 signaling pathway with AMD3100-conjugated nanoparticles (SPNPs). (1) Radiotherapy induces glioma cell death, followed by Damage-associated molecular patterns (DAMPs) release. Dendritic cells (DC) are activated by DAMPs and migrate to the regional lymph node where they prime cytotoxic T lymphocyte immune response. Tumor-specific cytotoxic T cells infiltrate the tumor and attack glioma cells. (2) Glioma cells express CXCR4, as well its ligand CXCL12. CXCL12 induces glioma cell proliferation and, (3) as well as mobilization in the bone marrow of CXCR4 expressing myeloid MDSC, which will infiltrate the tumor, and inhibit tumor-specific cytotoxic T cells activity. GEMM of glioma when treated systemically with SPNPs AMD3100 SPNPs plus radiation, nanoparticles block the interaction between CXCR4 and CXCL12, thus (4) inhibiting glioma cell proliferation and (5) reducing mobilization in the bone marrow of CXCR4 expressing myeloid MDSC, (6) generating a reduced MDSC tumor infiltration, as well as releasing MDSC inhibition over tumor specific cytotoxic T cell response. C_FIG

cell biology↗