The Role of Rho GTPases in Motility and Invasion of Glioblastoma Cells

Extracellular vesicles secreted by 3D tumor organoids are enriched for immune regulatory signaling biomolecules compared to conventional 2D glioblastoma cell systems

Background

Newer 3D culturing approaches are a promising way to better mimic the in vivo tumor microenvironment and to study the interactions between the heterogeneous cell populations of glioblastoma multiforme. Like many other tumors, glioblastoma uses extracellular vesicles as an intercellular communication system to prepare surrounding tissue for invasive tumor growth. However, little is known about the effects of 3D culture on extracellular vesicles. The aim of this study was to comprehensively characterize extracellular vesicles in 3D organoid models and compare them to conventional 2D cell culture systems.

Methods

Primary glioblastoma cells were cultured as 2D and 3D organoid models. Extracellular vesicles were obtained by precipitation and immunoaffinity, with the latter allowing targeted isolation of the CD9/CD63/CD81 vesicle subpopulation. Comprehensive vesicle characterization was performed and miRNA expression profiles were generated by smallRNA-sequencing. In silico analysis of differentially regulated miRNAs was performed to identify mRNA targets and corresponding signaling pathways. The tumor cell media and extracellular vesicle proteome were analyzed by high-resolution mass spectrometry.

Results

We observed an increased concentration of extracellular vesicles in 3D organoid cultures. Differential gene expression analysis further revealed the regulation of twelve miRNAs in 3D tumor organoid cultures (with nine miRNAs down and three miRNAs upregulated). MiR-23a-3p, known to be involved in glioblastoma invasion, was significantly increased in 3D. MiR-7-5p, which counteracts glioblastoma malignancy, was significantly decreased. Moreover, we identified four miRNAs (miR-323a-3p, miR-382-5p, miR-370-3p, miR-134-5p) located within the DLK1-DIO3 domain, a cancer-associated genomic region, suggesting a possible importance of this region in glioblastoma progression. Overrepresentation analysis identified alterations of extracellular vesicle cargo in 3D organoids, including representation of several miRNA targets and proteins primarily implicated in the immune response.

Conclusion

Our results show that 3D glioblastoma organoid models secrete extracellular vesicles with an altered cargo compared to corresponding conventional 2D cultures. Extracellular vesicles from 3D cultures were found to contain signaling molecules associated with the immune regulatory signaling pathways and as such could potentially change the surrounding microenvironment towards tumor progression and immunosuppressive conditions. These findings suggest the use of 3D glioblastoma models for further clinical biomarker studies as well as investigation of new therapeutic options.

Assessing the mechanism of fast-cycling cancer-associated mutations of Rac1 small Rho GTPase

Rho-GTPases proteins function as molecular switches alternating from an active to an inactive state upon Guanosine triphosphate (GTP) binding and hydrolysis to Guanosine diphosphate (GDP). Among them, Rac subfamily regulates cell dynamics, being overexpressed in distinct cancer types. Notably, these proteins are object of frequent cancer-associated mutations at Pro29 (P29S, P29L, and P29Q). To assess the impact of these mutations on Rac1 structure and function, we performed extensive all-atom molecular dynamics simulations on wild-type (wt) and oncogenic isoforms of this protein in GDP- and GTP-bound states. Our results unprecedentedly elucidate that P29Q/S-induced structural and dynamical perturbations of Rac1 core domain weaken the binding of the catalytic site Mg2+ ion, and reduce the GDP residence time within protein, enhancing the GDP/GTP exchange rate and Rac1 activity. This broadens our knowledge of the role of cancer-associated mutations on small GTPases mechanism supplying valuable information for future drug discovery efforts targeting specific Rac1 isoforms.

The C. elegans anchor cell: A model to elucidate mechanisms underlying invasion through basement membrane

Cell invasion through basement membrane barriers is crucial during many developmental processes and in immune surveillance. Dysregulation of invasion also drives the pathology of numerous human diseases, such as metastasis and inflammatory disorders. Cell invasion involves dynamic interactions between the invading cell, basement membrane, and neighboring tissues. Owing to this complexity, cell invasion is challenging to study in vivo, which has hampered the understanding of mechanisms controlling invasion. Caenorhabditis elegans anchor cell invasion is a powerful in vivo model where subcellular imaging of cell-basement membrane interactions can be combined with genetic, genomic, and single-cell molecular perturbation studies. In this review, we outline insights gained by studying anchor cell invasion, which span transcriptional networks, translational regulation, secretory apparatus expansion, dynamic and adaptable protrusions that breach and clear basement membrane, and a complex, localized metabolic network that fuels invasion. Together, investigation of anchor cell invasion is building a comprehensive understanding of the mechanisms that underlie invasion, which we expect will ultimately facilitate better therapeutic strategies to control cell invasive activity in human disease.

Differences and similarities in biophysical and biological characteristics between U87 MG glioblastoma and astrocyte cells

Current cancer studies focus on molecular-targeting diagnostics and interactions with surroundings; however, there are still gaps in characterization based on topological differences and elemental composition. Glioblastoma (GBM cells; GBMCs) is an astrocytic aggressive brain tumor. At the molecular level, GBMCs and astrocytes may differ, and cell elemental/topological analysis is critical for identifying potential new cancer targets. Here, we used U87 MG cells for GBMCS. U87 MG cell lines, which are frequently used in glioblastoma research, are an important tool for studying the various features and underlying mechanisms of this aggressive brain tumor. For the first time, atomic force microscopy (AFM), scanning electron microscopy (SEM) accompanied by energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) are used to report the topology and chemistry of cancer (U87 MG) and healthy (SVG p12) cells. In addition, F-actin staining and cytoskeleton-based gene expression analyses were performed. The degree of gene expression for genes related to the cytoskeleton was similar; however, the intensity of F-actin, anisotropy values, and invasion-related genes were different. Morphologically, GBMCs were longer and narrower while astrocytes were shorter and more disseminated based on AFM. Furthermore, the roughness values of these cells differed slightly between the two call types. In contrast to the rougher astrocyte surfaces in the lamellipodial area, SEM-EDS analysis showed that elongated GBMCs displayed filopodial protrusions. Our investigation provides considerable further insight into rapid cancer cell characterization in terms of a combinatorial spectroscopic and microscopic approach.

Rhizochalinin Exhibits Anticancer Activity and Synergizes with EGFR Inhibitors in Glioblastoma In Vitro Models

Rhizochalinin (Rhiz) is a recently discovered cytotoxic sphingolipid synthesized from the marine natural compound rhizochalin. Previously, Rhiz demonstrated high in vitro and in vivo efficacy in various cancer models. Here, we report Rhiz to be highly active in human glioblastoma cell lines as well as in patient-derived glioma-stem like neurosphere models. Rhiz counteracted glioblastoma cell proliferation by inducing apoptosis, G2/M-phase cell cycle arrest, and inhibition of autophagy. Proteomic profiling followed by bioinformatic analysis suggested suppression of the Akt pathway as one of the major biological effects of Rhiz. Suppression of Akt as well as IGF-1R and MEK1/2 kinase was confirmed in Rhiz-treated GBM cells. In addition, Rhiz pretreatment resulted in a more pronounced inhibitory effect of γ-irradiation on the growth of patient-derived glioma-spheres, an effect to which the Akt inhibition may also contribute decisively. In contrast, EGFR upregulation, observed in all GBM neurospheres under Rhiz treatment, was postulated to be a possible sign of incipient resistance. In line with this, combinational therapy with EGFR-targeted tyrosine kinase inhibitors synergistically increased the efficacy of Rhiz resulting in dramatic inhibition of GBM cell viability as well as a significant reduction of neurosphere size in the case of combination with lapatinib. Preliminary in vitro data generated using a parallel artificial membrane permeability (PAMPA) assay suggested that Rhiz cannot cross the blood brain barrier and therefore alternative drug delivery methods should be used in the further in vivo studies. In conclusion, Rhiz is a promising new candidate for the treatment of human glioblastoma, which should be further developed in combination with EGFR inhibitors.

Inhibition of induced-hepatic cancer in vivo through IQGAP1-shRNA gene therapy and modulation of TRAIL-induced apoptosis pathway

Background

Liver cancer is the deadliest malignancy among common tumors. It is the top cause of cancer-related deaths in Egypt, and it is characterized by increasing occurrence among the population. The objective of this study was to determine the outcome of pre-treatment of IQGAP1-shRNA on induced mouse hepatocellular carcinoma model and evaluate the potency of this IQGAP1-shRNA plasmid to recover hepatic cancer as a new tool of cancer therapy. Therefore, we will use RNA interference (RNAi) technology to silence IQGAP1 oncogene to completely recover the chemically induced models for hepatic cancer by designing short RNAi specific for IQGAP1 gene in HCC cells in vivo and construct new vectors suitable for this purpose. We assigned mice into three groups: the first negative control group (NC) was injected with saline, the second control group was injected with shRNA (shNC), the third positive control group was injected with diethylnitrosamine (DENAA), and the fourth group was treated with the IQGAP1-shRNA prior to its exposure to DENA.

Results

Our results revealed that the treated group with IQGAP1-shRNA with DENA developed very few cases of hepatic cancer when compared with the positive control group. The positive control group exhibited significant increases in the liver function level as well as a decrease in serum albumin levels when compared to both the treated and the negative control groups. The altered levels of the serum α-fetoprotein as well as of the tumor necrosis factor-alpha, and interleukin-4 in DENA-treated mice were significantly ameliorated by IQGAP1-shRNA administration. Flow cytometer analyses have indicated that the silencing of IQGAP1 cannot significantly modulate DENA-induced apoptosis in the circulating blood cells. Moreover, the elevated mRNA expression levels of IQGAP1, IQGAP3, KRas, HRas, interleukin-8, nuclear factor kappa B, caspase-3, caspase-9 and Bcl-2, were significantly decreased by the IQGAP1-shRNA treatment. However, the IQGAP2, DR4, DR5, p53 and BAX genes were found to be significantly up-regulated post-therapy. In agreement with these findings, IQGAP1-shRNA was able to modulate the DENA-induced histological changes in the mice liver which were represented by severe necrosis and hydropic degenerative changes.

Conclusion

Our study revealed that IQGAP1-shRNA was able to preserve hepatocyte integrity and the liver histological architecture through the regulation of the expression of IQGAPs, Ras, TRAILs and IL-8 receptors, as well as of pro-apoptotic and anti-apoptotic genes. Therefore, the silencing of IQGAP1 could be part of a promising therapeutic strategy against hepatic cancer.

Identification of cervical squamous cell carcinoma feature genes and construction of a prognostic model based on immune-related features

As heterogeneity of cervical squamous cell carcinoma (CSCC), prognosis assessment for CSCC patients remain challenging. To develop novel prognostic strategies for CSCC patients, associated biomarkers are urgently needed. This study aimed to cluster CSCC samples from a molecular perspective. CSCC expression data sets were obtained from The Cancer Genome Atlas and based on the accessed expression profile, a co-expression network was constructed with weighted gene co-expression network analysis to form different gene modules. Tumor microenvironment was evaluated using ESTIMATE algorithm, observing that the brown module was highly associated with tumor immunity. CSCC samples were clustered into three subtypes by consensus clustering based on gene expression profiles in the module. Gene set variation analysis showed differences in immune-related pathways among the three subtypes. CIBERSORT and single-sample gene set enrichment analysis analyses showed the difference in immune cell infiltration among subtype groups. Also, Human leukocyte antigen protein expression varied considerably among subtypes. Subsequently, univariate, Lasso and multivariate Cox regression analyses were performed on the genes in the brown module and an 8-gene prognostic model was constructed. Kaplan-Meier analysis illuminated that the low-risk group manifested a favorable prognosis, and receiver operating characteristic curve showed that the model has good predictive performance. qRT-PCR was used to examine the expression status of the prognosis-associated genes. In conclusion, this study identified three types of CSCC from a molecular perspective and established an effective prognostic model for CSCC, which will provide guidance for clinical subtype identification of CSCC and treatment of patients.

Screening seven hub genes associated with prognosis and immune infiltration in glioblastoma

Glioblastoma (GBM) is the most common and deadly primary brain tumor in adults. Diagnostic and therapeutic challenges have been raised because of poor prognosis. Gene expression profiles of GBM and normal brain tissue samples from GSE68848, GSE16011, GSE7696, and The Cancer Genome Atlas (TCGA) were downloaded. We identified differentially expressed genes (DEGs) by differential expression analysis and obtained 3,800 intersected DEGs from all datasets. Enrichment analysis revealed that the intersected DEGs were involved in the MAPK and cAMP signaling pathways. We identified seven different modules and 2,856 module genes based on the co-expression analysis. Module genes were used to perform Cox and Kaplan-Meier analysis in TCGA to obtain 91 prognosis-related genes. Subsequently, we constructed a random survival forest model and a multivariate Cox model to identify seven hub genes (KDELR2, DLEU1, PTPRN, SRBD1, CRNDE, HPCAL1, and POLR1E). The seven hub genes were subjected to the risk score and survival analyses. Among these, CRNDE may be a key gene in GBM. A network of prognosis-related genes and the top three differentially expressed microRNAs with the largest fold-change was constructed. Moreover, we found a high infiltration of plasmacytoid dendritic cells and T helper 17 cells in GBM. In conclusion, the seven hub genes were speculated to be potential prognostic biomarkers for guiding immunotherapy and may have significant implications for the diagnosis and treatment of GBM.

Glioblastoma: Current Status, Emerging Targets, and Recent Advances

Glioblastoma (GBM) is a highly malignant brain tumor characterized by a heterogeneous population of genetically unstable and highly infiltrative cells that are resistant to chemotherapy. Although substantial efforts have been invested in the field of anti-GBM drug discovery in the past decade, success has primarily been confined to the preclinical level, and clinical studies have often been hampered due to efficacy-, selectivity-, or physicochemical property-related issues. Thus, expansion of the list of molecular targets coupled with a pragmatic design of new small-molecule inhibitors with central nervous system (CNS)-penetrating ability is required to steer the wheels of anti-GBM drug discovery endeavors. This Perspective presents various aspects of drug discovery (challenges in GBM drug discovery and delivery, therapeutic targets, and agents under clinical investigation). The comprehensively covered sections include the recent medicinal chemistry campaigns embarked upon to validate the potential of numerous enzymes/proteins/receptors as therapeutic targets in GBM.

Dematin inhibits glioblastoma malignancy through RhoA-mediated CDKs downregulation and cytoskeleton remodeling

Glioblastoma multiforme (GBM) is well known as a highly aggressive brain tumor subtype. Here, we show that overexpression (OE) of dematin actin-binding protein (DMTN) inhibits GBM proliferation and invasion by affecting cell cycle regulation and actin remodeling, respectively. RT-qPCR, western blotting, and immunohistochemical (IHC) staining demonstrated a significant reduction in DMTN expression in gliomas, especially in high-grade gliomas (HGG) compared with normal brains, which correlates with worse survival in HGG patients. Functional studies revealed inhibitory effects of DMTN on tumor proliferation and migratory capacities. The attenuation in tumor proliferative ability upon DMTN OE was accompanied by RhoA suppression and CDK1, CDK2, CDK4, and cyclin D1 downregulation, while RhoA rescue restored the proliferative phenotype. Meanwhile, overexpression of DMTN produced profoundly disorganized stress fibers, which led to impaired tumor invasion. Furthermore, DMTN overexpression produced substantial suppression of tumor growth upon subcutaneous and intracranial implantation in mice, and this was accompanied by significantly reduced vinculin expression and Ki67 positivity. Taken together, these findings demonstrate the role of DMTN in regulating GBM cell proliferation, actin cytoskeleton, and cell morphology and identify DMTN as a vital tumor suppressor in GBM progression.

Overexpressed or hyperactivated Rac1 as a target to treat hepatocellular carcinoma

Despite novel targeted and immunotherapies, the prognosis remains bleak for patients with hepatocellular carcinoma (HCC), especially for advanced and/or metastatic forms. The rapid emergence of drug resistance is a major obstacle in the success of chemo-, targeted-, immuno-therapies of HCC. Novel targets are needed. The prominent roles of the small GTPase Rac1 in the development and progression of HCC are discussed here, together with its multiple protein partners, and the targeting of Rac1 with RNA-based regulators and small molecules. We discuss the oncogenic functions of Rac1 in HCC, including the contribution of Rac1 mutants and isoform Rac1b. Rac1 is a ubiquitous target, but the protein is frequently overexpressed and hyperactivated in HCC. It contributes to the aggressivity of the disease, with key roles in cancer cell proliferation, tumor metastasis and resistance to treatment. Small molecule targeting Rac1, indirectly or directly, have shown anticancer effects in HCC experimental models. Rac1-binding agents such as EHT 1864 and analogues offer novel opportunities to combat HCC. We discuss the different modalities to repress Rac1 overactivation in HCC with small molecules and the combination with reference drugs to promote cancer cell death and to repress cell invasion. We highlight the necessity to combine Rac1-targeted approach with appropriate biomarkers to select Rac1 activated tumors. Our analysis underlines the prominent oncogenic functions of Rac1 in HCC and discuss the modalities to target this small GTPase. Rac1 shall be considered as a valid target to limit the acquired and intrinsic resistance of HCC tumors and their metastatic potential.

Immune Landscape of CMV Infection in Cancer Patients: From "Canonical" Diseases Toward Virus-Elicited Oncomodulation

Human Cytomegalovirus (HCMV) is an immensely pervasive herpesvirus, persistently infecting high percentages of the world population. Despite the apparent robust host immune responses, HCMV is capable of replicating, evading host defenses, and establishing latency throughout life by developing multiple immune-modulatory strategies. HCMV has coexisted with humans mounting various mechanisms to evade immune cells and effectively win the HCMV-immune system battle mainly through maintaining its viral genome, impairing HLA Class I and II molecule expression, evading from natural killer (NK) cell-mediated cytotoxicity, interfering with cellular signaling, inhibiting apoptosis, escaping complement attack, and stimulating immunosuppressive cytokines (immune tolerance). HCMV expresses several gene products that modulate the host immune response and promote modifications in non-coding RNA and regulatory proteins. These changes are linked to several complications, such as immunosenescence and malignant phenotypes leading to immunosuppressive tumor microenvironment (TME) and oncomodulation. Hence, tumor survival is promoted by affecting cellular proliferation and survival, invasion, immune evasion, immunosuppression, and giving rise to angiogenic factors. Viewing HCMV-induced evasion mechanisms will play a principal role in developing novel adapted therapeutic approaches against HCMV, especially since immunotherapy has revolutionized cancer therapeutic strategies. Since tumors acquire immune evasion strategies, anti-tumor immunity could be prominently triggered by multimodal strategies to induce, on one side, immunogenic tumor apoptosis and to actively oppose the immune suppressive microenvironment, on the other side.

GTPBP2 positively regulates the invasion, migration and proliferation of non-small cell lung cancer

Lung cancer is one of the most common malignant tumors in the world, and the mortality rate ranks first among various malignant tumors. GTP-binding proteins (guanosine 5'-triphosphate-binding proteins, GTPBPs) are a type of protein with signal transduction function, have GTP hydrolase activity, and play an important role in cell signal transmission, cytoskeletal regulation, protein synthesis and other activities. GTPBP2 is one of the members of the G protein superfamily. Research on GTPBP2 is currently focused on human genetics, and its research in tumors has not been reported. First, Western blot and quantitative real-time PCR were used to analyze the expression differences of 12 cases of GTPBP2 in human NSCLC fresh cancer tissues and adjacent tissues. Then we selected 112 cases of NSCLC cancer tissues and 65 adjacent tissues for immunohistochemistry experiments to analyze the relationships between the expression of GTPBP2 and clinical pathological parameters and prognosis, we found that GTPBP2 is highly expressed in NSCLC cancer tissues, and the high expression of GTPBP2 is related to pTNM stage and lymph node metastasis. In addition, after GTPBP2 knockdown, GTPBP2 can promote the proliferation and invasion of NSCLC cell lines by up-regulating RhoC and MMP-9, and up-regulate cyclinD1, CDK4 and c-myc, and down-regulate P27 to promote the invasion of NSCLC cell lines. In addition, GTPBP2 negatively regulates Axin to promote β-catenin expression, thereby activating Wnt/β-catenin signaling, and promoting the occurrence of NSCLC.

Dysregulation of Rho GTPases in orofacial cleft patients-derived primary cells leads to impaired cell migration, a potential cause of cleft/lip palate development

Cleft lip and/or palate are a split in the lip, the palate or both. This results from the inability of lip buds and palatal shelves to properly migrate and assemble during embryogenesis. By extracting primary cells from a cleft patient, we aimed at offering a better understanding of the signaling mechanisms and interacting molecules involved in the lip and palate formation and fusion. With Rho GTPases being indirectly associated with cleft occurrence, we investigated the role of the latter in both. First, whole exome sequencing was conducted in a patient with cleft lip and palate. Primary fibroblastic cells originating from the upper right gingiva region were extracted and distinct cellular populations from two individuals were obtained: a control with no cleft phenotype and a patient with a cleft lip and palate. The genetic data showed three candidate variables in ARHGEF18, EPDR1, and CUL7. Next, the molecular data showed no significant change in proliferation rates between healthy patient cells and CL/P patient cells. However, CL/P patient cells showed decreased migration, increased adhesion and presented with a more elongated phenotype. Additionally, RhoA activity was upregulated in these cells, whereas Cdc42 activity was downregulated, resulting in loss of polarity. Our results are suggestive of a possible correlation between a dysregulation of Rho GTPases and the observed phenotype of cleft lip and palate patient cells. This insight into the intramolecular aspect of this disorder helps link the genetic defect with the observed phenotype and offers a possible mechanism by which CL/P occurs.

Human recombinant arginase I [HuArgI (Co)-PEG5000]-induced arginine depletion inhibits ovarian cancer cell adhesion and migration through autophagy-mediated inhibition of RhoA

Ovarian carcinoma is the second most common malignancy of the female reproductive system and the leading cause of death from female reproductive system malignancies. Cancer cells have increased proliferation rate and thus require high amounts of amino acids, including arginine. L-arginine is a non-essential amino acid synthesized from L-citrulline by the Arginosuccinate synthetase (ASS1) enzyme. We have previously shown that the ovarian cancer cells, SKOV3, are auxotrophic to arginine, and that arginine deprivation by treatment with the genetically engineered human arginase I (HuArgI (Co)-PEG5000) triggers the death of SKOV3 cells by autophagy. In this study we examine the effect of HuArgI (Co)-PEG5000 on ovarian cancer cell migration and we dissect the mechanism involved. Wound healing assays, 2D random cell migration assays and cell adhesion analysis indicate that arginine deprivation decreases SKOV3 cell migration and adhesion. This effect was mimicked when autophagy was induced through rapamycin and reversed with the autophagy inhibitor chloroquine when autophagy was inhibited. This proved that arginine deprivation leads to the inhibition of cancer cell migration through autophagy, in addition to cell death. In addition, we were able to establish through pull-down assays and reversal experiments, that arginine deprivation-mediated autophagy inhibits cell migration through a direct inhibition of RhoA, member of the Rho family of GTPases. In conclusion, here we identify, for the first time, an autophagy-mediated inhibition of RhoA that plays an important role in regulating ovarian cancer cells motility and adhesion in response to arginine depletion.

Recombinant anthrax lethal toxin inhibits cell motility and invasion in breast cancer cells through the dysregulation of Rho GTPases

Breast cancer is the leading cause of cancer-associated death among women worldwide. Targeting breast cancer cell metastasis is an important therapeutic approach. The MAPK pathway is a key cell signaling pathway that plays a pivotal role in cellular invasion and migration. Numerous studies have identified the MAPK pathway as a way to target cell survival and motility. The present study treated MBA-MD-231 breast cancer cells with anthrax lethal toxin (LeTx), a potent MAPK inhibitor that selectively cleaves and inactivates all MEKs, as a potential therapeutic method to inhibit breast cancer cell migration. LeTx has been demonstrated to affect breast cancer cell migration. Cells treated with LeTx showed a significant decrease in motility, as observed using wound healing and random 2D motility assays. Additionally, cells treated with LeTx showed an increase in adhesion, which would explain the decrease in migration. Pull-down assays examining the activation status of the members of the Rho family of GTPases revealed an increase in RhoA activation accompanied by a decrease in Cdc42 activation following LeTx treatment. Finally, LeTx mediated a decrease in invasion using a Boyden chamber assay, which could be a result of the decrease in Cdc42 activation. The present study reported the effect of LeTx treatment on the migration, adhesion and invasion of breast cancer cells, demonstrating that this effect was associated with the dysregulation of the Rho GTPases, RhoA and Cdc42.

Role of Fibroblast Growth Factors Receptors (FGFRs) in Brain Tumors, Focus on Astrocytoma and Glioblastoma

Despite pharmacological treatments and surgical practice options, the mortality rate of astrocytomas and glioblastomas remains high, thus representing a medical emergency for which it is necessary to find new therapeutic strategies. Fibroblast growth factors (FGFs) act through their associated receptors (FGFRs), a family of tyrosine kinase receptors consisting of four members (FGFR1-4), regulators of tissue development and repair. In particular, FGFRs play an important role in cell proliferation, survival, and migration, as well as angiogenesis, thus their gene alteration is certainly related to the development of the most common diseases, including cancer. FGFRs are subjected to multiple somatic aberrations such as chromosomal amplification of FGFR1; mutations and multiple dysregulations of FGFR2; and mutations, translocations, and significant amplifications of FGFR3 and FGFR4 that correlate to oncogenesis process. Therefore, the in-depth study of these receptor systems could help to understand the etiology of both astrocytoma and glioblastoma so as to achieve notable advances in more effective target therapies. Furthermore, the discovery of FGFR inhibitors revealed how these biological compounds improve the neoplastic condition by demonstrating efficacy and safety. On this basis, this review focuses on the role and involvement of FGFRs in brain tumors such as astrocytoma and glioblastoma.

TRP Channels Regulation of Rho GTPases in Brain Context and Diseases

Neurological and neuropsychiatric disorders are mediated by several pathophysiological mechanisms, including developmental and degenerative abnormalities caused primarily by disturbances in cell migration, structural plasticity of the synapse, and blood-vessel barrier function. In this context, critical pathways involved in the pathogenesis of these diseases are related to structural, scaffolding, and enzymatic activity-bearing proteins, which participate in Ca²⁺- and Ras Homologs (Rho) GTPases-mediated signaling. Rho GTPases are GDP/GTP binding proteins that regulate the cytoskeletal structure, cellular protrusion, and migration. These proteins cycle between GTP-bound (active) and GDP-bound (inactive) states due to their intrinsic GTPase activity and their dynamic regulation by GEFs, GAPs, and GDIs. One of the most important upstream inputs that modulate Rho GTPases activity is Ca²⁺ signaling, positioning ion channels as pivotal molecular entities for Rho GTPases regulation. Multiple non-selective cationic channels belonging to the Transient Receptor Potential (TRP) family participate in cytoskeletal-dependent processes through Ca²⁺-mediated modulation of Rho GTPases. Moreover, these ion channels have a role in several neuropathological events such as neuronal cell death, brain tumor progression and strokes. Although Rho GTPases-dependent pathways have been extensively studied, how they converge with TRP channels in the development or progression of neuropathologies is poorly understood. Herein, we review recent evidence and insights that link TRP channels activity to downstream Rho GTPase signaling or modulation. Moreover, using the TRIP database, we establish associations between possible mediators of Rho GTPase signaling with TRP ion channels. As such, we propose mechanisms that might explain the TRP-dependent modulation of Rho GTPases as possible pathways participating in the emergence or maintenance of neuropathological conditions.

RHOAming Through the Nucleotide Excision Repair Pathway as a Mechanism of Cellular Response Against the Effects of UV Radiation

Typical Rho GTPases include the enzymes RhoA, Rac1, and Cdc42 that act as molecular switches to regulate essential cellular processes in eukaryotic cells such as actomyosin dynamics, cell cycle, adhesion, death and differentiation. Recently, it has been shown that different conditions modulate the activity of these enzymes, but their functions still need to be better understood. Here we examine the interplay between RhoA and the NER (Nucleotide Excision Repair) pathway in human cells exposed to UVA, UVB or UVC radiation. The results show high levels and accumulation of UV-induced DNA lesions (strand breaks and cyclobutane pyrimidine dimers, CPDs) in different cells with RhoA loss of function (LoF), either by stable overexpression of negative dominant RhoA (RhoA-N19 mutant), by inhibition with C3 toxin or by transient silencing with siRNA. Cells under RhoA LoF showed reduced levels of γH2AX, p-Chk1 (Ser345) and p-p53 (Ser15) that reflected causally in their accumulation in G1/S phases, in low survival rates and in reduced cell proliferation, also in accordance with the energy of applied UV light. Even NER-deficient cells (XPA, XPC) or DNA translesion synthesis (TLS)-deficient cells (XPV) showed substantial hypersensitivity to UV effects when previously submitted to RhoA LoF. In contrast, analyses of apoptosis, necrosis, autophagy and senescence revealed that all cells displaying normal levels of active RhoA (RhoA-GTP) are more resistant to UV-promoted cell death. This work reaffirms the role of RhoA protein signaling in protecting cells from damage caused by UV radiation and demonstrates relevant communicating mechanisms between actin cytoskeleton and genomic stability.

Glioblastoma chemoresistance: roles of the mitochondrial melatonergic pathway

Treatment-resistance is common in glioblastoma (GBM) and the glioblastoma stem-like cells (GSC) from which they arise. Current treatment options are generally regarded as very poor and this arises from a poor conceptualization of the biological underpinnings of GBM/GSC and of the plasticity that these cells are capable of utilizing in response to different treatments. A number of studies indicate melatonin to have utility in the management of GBM/GSC, both per se and when adjunctive to chemotherapy. Recent work shows melatonin to be produced in mitochondria, with the mitochondrial melatonergic pathway proposed to be a crucial factor in driving the wide array of changes in intra- and inter-cellular processes, as well as receptors that can be evident in the cells of the GBM/GSC microenvironment. Variations in the enzymatic conversion of N-acetylserotonin (NAS) to melatonin may be especially important in GSC, as NAS can activate the tyrosine receptor kinase B to increase GSC survival and proliferation. Consequently, variations in the NAS/melatonin ratio may have contrasting effects on GBM/GSC survival. It is proposed that mitochondrial communication across cell types in the tumour microenvironment is strongly driven by the need to carefully control the mitochondrial melatonergic pathways across cell types, with a number of intra- and inter-cellular processes occurring as a consequence of the need to carefully regulate the NAS/melatonin ratio. This better integrates previously disparate data on GBM/GSC as well as providing clear future research and treatment options.

Actin Alpha 2 (ACTA2) Downregulation Inhibits Neural Stem Cell Migration through Rho GTPase Activation

Although neural stem cells (NSCs) could migrate towards lesions after central nervous system (CNS) injury, the migration ability always is restricted due to the disturbed composition and density of the adhesion ligands and extracellular matrix (ECM) gradient after CNS injury. To date, various methods have been developed to enhance NSC migration and a number of factors, which are affecting NSC migration potential, have been identified. Here, primary NSCs were cultured and the expression of actin alpha 2 (ACTA2) in NSCs was determined using reverse transcription polymerase chain reaction (RT-PCR) and immunostaining. Next, the role of ACTA2 in regulating NSC migration and the potential mechanism was explored. Our results demonstrated that ACTA2 expressed in NSCs. Meanwhile, downregulated ACTA2 using siRNA inhibited NSC migration through hindering actin filament polymerization via increasing RhoA expression and decreasing Rac1 expression. The present study might enrich the basic knowledge of ACTA2 in NSC migration and open an avenue for enhancing NSC migration potential, subsequently providing an intervention target for functional recovery after CNS injury.

The Role of Rho GTPases in VEGF Signaling in Cancer Cells

Vascular endothelial growth factors (VEGFs) consist of five molecules (VEGFA through D as well as placental growth factor) which are crucial for regulating key cellular and tissue functions. The role of VEGF and its intracellular signaling and downstream molecular pathways have been thoroughly studied. Activation of VEGF signal transduction can be initiated by the molecules' binding to two classes of transmembrane receptors: (1) the VEGF tyrosine kinase receptors (VEGF receptors 1 through 3) and (2) the neuropilins (NRP1 and 2). The involvement of Rho GTPases in modulating VEGFA signaling in both cancer cells and endothelial cells has also been well established. Additionally, different isoforms of Rho GTPases, namely, RhoA, RhoC, and RhoG, have been shown to regulate VEGF expression as well as blood vessel formation. This review article will explore how Rho GTPases modulate VEGF signaling and the consequences of such interaction on cancer progression.

Promising Anti-atherosclerotic Effect of Berberine: Evidence from In Vitro, In Vivo, and Clinical Studies

Elevated levels of plasma cholesterol, impaired vascular wall, and presence of inflammatory macrophages are important atherogenic risk factors contributing to atherosclerotic plaque formation and progression. The interventions modulating these risk factors have been found to protect against atherosclerosis development and to decrease atherosclerosis-related cardiovascular disorders. Nutritional approaches involving supplements followed by improving dietary habits and lifestyle have become growingly attractive and acceptable methods used to control atherosclerosis risk factors, mainly high levels of plasma cholesterol. There are a large number of studies that show berberine, a plant bioactive compound, could ameliorate atherosclerosis-related risk factors. In the present literature review, we put together this studies and provide integrated evidence that exhibits berberine has the potential atheroprotective effect through reducing increased levels of plasma cholesterol, particularly low-density lipoprotein (LDL) cholesterol (LDL-C) via LDL receptor (LDLR)-dependent and LDL receptor-independent mechanisms, inhibiting migration and inflammatory activity of macrophages, improving the functionality of endothelial cells via anti-oxidant activities, and suppressing proliferation of vascular smooth muscle cells. In conclusion, berberine can exert inhibitory effects on the atherosclerotic plaque development mainly through LDL-lowering activity and suppressing atherogenic functions of mentioned cells. As the second achievement of this review, among the signaling pathways through which berberine regulates intracellular processes, AMP-activated protein kinase (AMPK) has a central and critical role, showing that enhancing activity of AMPK pathway can be considered as a promising therapeutic approach for atherosclerosis treatment.