Down‐Regulation of AQP4 Expression via p38 MAPK Signaling in Temozolomide‐Induced Glioma Cells Growth Inhibition and Invasion Impairment

Multiomics2Targets identifies targets from cancer cohorts profiled with transcriptomics, proteomics, and phosphoproteomics

The availability of data from profiling of cancer patients with multiomics is rapidly increasing. However, integrative analysis of such data for personalized target identification is not trivial. Multiomics2Targets is a platform that enables users to upload transcriptomics, proteomics, and phosphoproteomics data matrices collected from the same cohort of cancer patients. After uploading the data, Multiomics2Targets produces a report that resembles a research publication. The uploaded matrices are processed, analyzed, and visualized using the tools Enrichr, KEA3, ChEA3, Expression2Kinases, and TargetRanger to identify and prioritize proteins, genes, and transcripts as potential targets. Figures and tables, as well as descriptions of the methods and results, are automatically generated. Reports include an abstract, introduction, methods, results, discussion, conclusions, and references and are exportable as citable PDFs and Jupyter Notebooks. Multiomics2Targets is applied to analyze version 3 of the Clinical Proteomic Tumor Analysis Consortium (CPTAC3) pan-cancer cohort, identifying potential targets for each CPTAC3 cancer subtype. Multiomics2Targets is available from https://multiomics2targets.maayanlab.cloud/.

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

Homeostatic status of thyroid hormones and brain water movement as determinant factors in biology of cerebral gliomas: a pilot study using a bioinformatics approach

Introduction

The expression and localization of the water channel transporters, aquaporins (AQPs), in the brain are substantially modified in gliomas during tumorigenesis, cell migration, edema formation, and resolution. We hypothesized that the molecular changes associated with AQP1 and AQP4 in the brain may potentially be anticancer therapeutic targets. To test this hypothesis, a bioinformatics analysis of publicly available data from international consortia was performed.

Methods

We used RNA-seq as an experimental strategy and identified the number of differential AQP1 and AQP4 transcript expressions in glioma tissue compared to normal brain tissue.

Results

AQPs genes are overexpressed in patients with glioma. Among the glioma subtypes, AQP1 and AQP4 were overexpressed in astrocytoma (low-grade glioma) and classical (high-grade glioma). Overall survival analysis demonstrated that both AQP genes can be used as prognostic factors for patients with low-grade glioma. Additionally, we observed a correlation between the expression of genes involved in the tyrosine and thyroid hormone pathways and AQPs, namely: PNMT, ALDH1A3, AOC2, HGDATP1B1, ADCY5, PLCB4, ITPR1, ATP1A3, LRP2, HDAC1, MED24, MTOR, and ACTB1 (Spearman's coefficient = geq 0.20 and p-value = ≤ 0.05).

Conclusion

Our findings indicate that the thyroid hormone pathways and AQPs 1 and 4 are potential targets for new anti-tumor drugs and therapeutic biomarkers for malignant gliomas.

Transmembrane water-efflux rate measured by magnetic resonance imaging as a biomarker of the expression of aquaporin-4 in gliomas

The water-selective channel protein aquaporin-4 (AQP4) contributes to the migration and proliferation of gliomas, and to their resistance to therapy. Here we show, in glioma cell cultures, in subcutaneous and orthotopic gliomas in rats, and in glioma tumours in patients, that transmembrane water-efflux rate is a sensitive biomarker of AQP4 expression and can be measured via conventional dynamic-contrast-enhanced magnetic resonance imaging. Water-efflux rates correlated with stages of glioma proliferation as well as with changes in the heterogeneity of intra-tumoural and inter-tumoural AQP4 in rodent and human gliomas following treatment with temozolomide and with the AQP4 inhibitor TGN020. Regions with low water-efflux rates contained higher fractions of stem-like slow-cycling cells and therapy-resistant cells, suggesting that maps of water-efflux rates could be used to identify gliomas that are resistant to therapies.

Identification of the prognostic and immunological roles of aquaporin 4: A potential target for survival and immunotherapy in glioma patients

Recent studies have revealed the critical role of AQP4 in the occurrence and development of gliomas. However, the role of AQP4 in immune regulation has not yet been reported. Many recent reports have identified the lymphatic system's occurrence within the central nervous system (CNS) and the vital role of immune regulation in treating brain tumors. Therefore, the present study aimed to explore the role of AQP4 in the immune regulation of glioma. We used bioinformatics analysis to investigate the immunoregulatory function of AQP4, including its correlation with immunity, anti-tumor immune processes, immunotherapy, immune infiltration, tumor mutational burden (TMB), stemness, mutation, and pan-cancer. The results revealed that AQP4 was significantly associated with the expression of multiple immune checkpoints, immune cells, as well as multiple immune cell effector genes, and antigen presentation and processing abilities. Although no significant correlation was found between the AQP4 gene and IDH mutation and MGMT, AQP4 demonstrated substantial expression differences in different immunophenotypes and molecular types. Using the TTD database, we discovered that EGFR, ABAT, and PDGFRA are strongly associated with AQP4 expression in the glioblastoma (GBM) classification, and these factors could be the potential AQP4-related immunotherapy targets. Afterward, we screened the differential genes in the high and low AQP4 gene expression group, the high and low immune score group, and the high and low matrix score group and took the intersection as the candidate factor. Finally, univariate Cox analysis was used to find eight prognostic variables with significant differences across the candidate genes. After lasso dimensionality reduction, three genes built the model (RARRES1, SOCS3, and TTYH1). The scoring model generated by the three genes was eventually obtained after the multi-factor screening of the three genes. Finally, combined with clinical information and cox regression analysis, it was further confirmed that the model score could be used as an independent prognostic factor.

Modulation of the p38 MAPK Pathway by Anisomycin Promotes Ferroptosis of Hepatocellular Carcinoma through Phosphorylation of H3S10

Hepatocellular carcinoma (HCC) is a prevalent malignant tumor worldwide. Ferroptosis is emerging as an effective target for tumor treatment as it has been shown to potentiate cell death in some malignancies. However, it remains unclear whether histone phosphorylation events, an epigenetic mechanism that regulates transcriptional expression, are involved in ferroptosis. Our study found that supplementation with anisomycin, an agonist of p38 mitogen-activated protein kinase (MAPK), induced ferroptosis in HCC cells, and the phosphorylation of histone H3 on serine 10 (p-H3S10) was participated in anisomycin-induced ferroptosis. To investigate the anticancer effects of anisomycin-activated p38 MAPK in HCC, we analyzed cell viability, colony formation, cell death, and cell migration in Hep3B and HCCLM3 cells. The results showed that anisomycin could significantly suppress HCC cell colony formation and migration and induce HCC cell death. The hallmarks of ferroptosis, such as abnormal accumulation of iron and elevated levels of lipid peroxidation and malondialdehyde, were detected to confirm the ability of anisomycin to promote ferroptosis. Furthermore, coincubation with SB203580, an inhibitor of activated p38 MAPK, partially rescued anisomycin-induced ferroptosis. And the levels of p-p38 MAPK and p-H3S10 were successively increased by anisomycin treatment. The relationship between p-H3S10 and ferroptosis was revealed by ChIP sequencing. The reverse transcription PCR and immunofluorescence results showed that NCOA4 was upregulated both in mRNA and protein levels after anisomycin treatment. And by C11-BODIPY staining, we found that anisomycin-induced lipid reactive oxygen species was reduced after NCOA4 knockdown. In conclusion, the anisomycin-activated p38 MAPK promoted ferroptosis of HCC cells through H3S10 phosphorylation.

The functional role of p38 MAPK pathway in malignant brain tumors

Gliomas are extremely debilitating malignant brain tumors with very limited response to therapies. The initiation and progression of gliomas can be attributed to several molecular abnormalities, such as mutations in important regulatory networks. In this regard, the mitogen-activated protein kinases (MAPKs) arise as key signaling pathways involved in cell proliferation, survival, and differentiation. MAPK pathway has been altered in most glial tumors. In glioma cells, the activation of p38 MAPK contributes to tumor invasion and metastasis and is positively correlated with tumor grade, being considered a potential oncogenic factor contributing to brain tumorigenesis and chemotherapy resistance. Hence, a better understanding of glioma pathogenesis is essential to the advancement of therapies that provide extended life expectancy for glioma patients. This review aims to explore the role of the p38 MAPK pathway in the genesis and progression of malignant brain tumors.

Sulforaphane Upregulates Cultured Mouse Astrocytic Aquaporin-4 Expression through p38 MAPK Pathway

Protein misfolding and/or aggregation are common pathological features associated with a number of neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson disease (PD). Abnormal protein aggregation may be caused by misfolding of the protein and/or dysfunction of the protein clearance system. Recent studies have demonstrated that the specific water channel protein, aquaporin-4 (AQP4), plays a role in the pathogenesis of neurodegenerative diseases involving protein clearance system. In this study, we aimed to investigate the role of sulforaphane (SFN) in the upregulation of AQP4 expression, along with its underlying mechanism using cultured mouse astrocytes as a model system. At low concentrations, SFN was found to increase cell proliferation and result in the activation of astrocytes. However, high SFN concentrations were found to suppress cell proliferation of astrocytes. In addition, our study found that a 1 μM concentration of SFN resulted in the upregulation of AQP4 expression and p38 MAPK phosphorylation in cultured mouse astrocytes. Moreover, we demonstrated that the upregulation of AQP4 expression was significantly attenuated when cells were pretreated with SB203580, a p38 MAPK inhibitor. In conclusion, our findings from this study revealed that SFN exerts hormesis effect on cultured mouse astrocytes and can upregulate astrocytic AQP4 expression by targeting the p38 MAPK pathway.

Identification of a novel autophagy-related prognostic signature and small molecule drugs for glioblastoma by bioinformatics

OBJECTIVE

To explore the autophagy-related prognostic signature (ARPs) via data mining in gene expression profiles for glioblastoma (GBM).

METHODS

Using the Cancer Genome Atlas (TCGA) database, we obtained 156 GBM samples and 5 adjacent normal samples, and denoted them as discovery cohort. Univariate Cox regression analysis was used to screen autophagy genes that related to GBM prognosis. Then, the least absolute shrinkage and selection operator Cox regression model was used to construct an autophagy-based ARPs, which was validated in an external cohort containing 80 GBM samples. The patients in the above-mentioned cohorts were divided into low-risk group and high-risk group according to the median prognostic risk score, and the diagnostic performance of the model was assessed by receiver operating characteristic curve analyses. The gene ontology and Kyoto encyclopedia of genes and genomes pathway enrichment analyses were performed between the high-risk and low-risk patients. Additionally, the genetic features of ARPs, such as genetic variation profiles, correlations with tumor-infiltrating lymphocytes (TILs), and potential drug sensitivity, were further assessed in the TCGA-GBM data set.

RESULTS

A signature of ARPs including NDUFB9, BAK1, SUPT3H, GAPDH, CDKN1B, CHMP6, and EGFR were detected and validated. We identified a autophagy-related prognosis 7-gene signature correlated survival prognosis, immune infiltration, level of cytokines, and cytokine receptor in tumor microenvironment. Furthermore, the signature was tested in several pathways related to disorders of tumor microenvironment, as well as cancer-related pathways. Additionally, a range of small molecular drugs, shown to have a potential therapeutic effect on GBM.

CONCLUSIONS

We constructed an autophagy-based 7-gene signature, which could serve as an independent prognostic indicator for cases of GBM and sheds light on the role of autophagy as a potential therapeutic target in GBM.

Dynamics of AQP4 upon exposure to seropositive patient serum before and after Rituximab therapy in Neuromyelitis Optica: A cell-based study

Neuromyelitis Optica (NMO) is an autoimmune inflammatory disease that affects the optic nerves and spinal cord. The autoantibody is generated against the abundant water channel protein of the brain, Aquaporin 4 (AQP4). Of the two isoforms of AQP4, the shorter one (M23) often exists as a supramolecular assembly known as an orthogonal array of particles (OAPs). There have been debates about the fate of these AQP4 clusters upon binding to the antibody, the exact mechanism of its turnover, and the proteins associated with the process. Recently several clinical cases of NMO were reported delineating the effect of Rituximab (RTX) therapy. Extending these reports at the cell signaling level, we developed a glioma based cellular model that mimicked antibody binding and helped us track the subsequent events including a variation of AQP4 levels, alterations in cellular morphology, and the changes in downstream signaling cascades. Our results revealed the extent of perturbations in the signaling pathways related to stress involving ERK, JNK, and AKT1 together with markers for cell death. We could also decipher the possible routes of degradation of AQP4, post-exposure to antibody. We further investigated the effect of autoantibody on AQP4 transcriptional level and involvement of FOXO3a and miRNA-145 in the regulation of transcription. This study highlights the differential outcome at the cellular level when treated with the serum of the same patient pre and post RTX therapy and for the first time mechanistically describes the effect of RTX.

Mechanism of Aquaporin-4 Up-Regulation After Traumatic Brain Injury and Preventative Action of Astragalus Polysaccharides in Mice

Here, we aimed to clarify the anti-inflammatory function of Astragalus Polysaccharides (APS), a chemical compound derived from Astragalus membranaceus, and the action of AQP4 on brain injury. We hypothesized that APS could improve the traumatic brain injury (TBI) outcome via inhibiting expression of AQP4 in astrocytes. The present study elucidated that AQP4 was up-regulated and was effectively blocked by APS in mice with severe controlled cortical impact (CCI). Pre-treatment with APS effectively inhibited the up-regulation of AQP4 and diminished the neurological deficits in mice. Additionally, primary astrocytes treated with mechanically-injured astrocyte supernatant, to mimic TBI in vitro, showed a significant up-regulation in swelling. We confirmed various signal molecules (NF-ĸB, MAPKs, and ERK) to have a role in astrocyte swelling, after activation in trauma, and to be involved in the up-regulation of AQP4. These signal molecules also significantly decreased with APS treatment. In conclusion, our study suggests that APS attenuated neurological deficits and brain edema by decreasing AQP4 up-regulation in astrocytes following TBI in mice, via reducing NF-ĸB, MAPKs, and the ERK signal molecules.

Aquaporin 4 and brain-related disorders: Insights into its apoptosis roles

Brain-related disorders are leading global health problems. Various internal and external factors are involved in the progression of brain-related disorders. Inflammatory pathways, oxidative stresses, apoptosis, and deregulations of various channels are critical players in brain-related disorder pathogenesis. Among these players, aquaporins (AQP) have critical roles in various physiological and pathological conditions. AQPs are water channel molecules that permit water to cross the hydrophobic lipid bilayers of cellular membranes. AQP4 is one of the important members of AQP family. AQPs are involved in controlling apoptosis pathways in brain-related disorders. In this regard, several reports have evaluated the pathological effects of AQP4 by targeting the apoptosis-related processes in brain-related disorders. Here, for the first time, we highlight the impact of AQP4 on apoptosis-related processes in brain-related disorders.

BIRB796, an Inhibitor of p38 Mitogen-Activated Protein Kinase, Inhibits Proliferation and Invasion in Glioblastoma Cells

Glioblastoma (GBM) is the most common malignant tumor, and it is characterized by high cellular proliferation and invasion in the central nervous system of adults. Due to its high degree of heterogeneity and mortality, there is no effective therapy for GBM. In our study, we investigated the effect of the p38-MAPK signaling pathway inhibitor BIRB796 on GBM cells. Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EDU) staining, and cell cycle distribution analysis were performed, and the results showed that BIRB796 decreased proliferation in U87 and U251 cells. Moreover, wound healing and invasion assays were performed, which showed that BIRB796 inhibited the migration and invasion of human GBM cells. We found that BIRB796 treatment significantly decreased the formation of the cytoskeleton and thus downregulated the movement ability of the cells, as shown by phalloidin staining and vimentin immunofluorescence staining. Real-time polymerase chain reaction showed that the mRNA levels of MMP-2, Vimentin, CyclinD1, and Snail-1 were downregulated. Consistently, the expressions of MMP-2, Vimentin, CyclinD1, and p-p38 were also decreased after BIRB796 treatment. Taken together, all our results demonstrated that BIRB796 could play an antitumor role by inhibiting the proliferation and invasion in GBM cells. Thus, BIRB796 may be used as an adjuvant therapy to improve the therapeutic efficacy of GBM treatment.

Aquaporins implicated in the cell proliferation and the signaling pathways of cell stemness

Aquaporins (AQPs) are water channel proteins facilitating passive transport of water and other small molecules across biomembranes. Regulation of osmotic homeostasis via AQPs is accompanied by dynamic participation of various cellular signaling pathways. Recently emerging evidence reveals that functional roles of AQPs are further extended from the osmotic regulation via water permeation into the cell proliferation and differentiation. In particular, anomalous expression of AQPs has been demonstrated in various types of cancer cells and cancer stem-like cells and it has been proposed as markers for proliferation and progression of cancer cells. Thus, a more comprehensive view on AQPs could bring a great interest in the cell stemness accompanied by the expression of AQPs. AQPs are broadly expressed across tissues and cells in a cell type- and lineage-specific manner during development via spatiotemporal transcriptional regulation. Moreover, AQPs are expressed in various adult stem cells and cells associated with a stem cell niche as well as cancer stem-like cells. However, the expression and regulatory mechanisms of AQP expression in stem cells have not been well understood. This review highlighted the AQPs expression in stem cell niches/stem cells and the involvement of AQPs in the cell proliferation and signaling pathways associated with cell stemness.

MiR-196b Promotes the Invasion and Migration of Lung Adenocarcinoma Cells by Targeting AQP4

Objective:

We aimed to investigate the mechanism of the regulatory axis of miR-196b/AQP4 underlying the invasion and migration of lung adenocarcinoma (LUAD) cells.

Methods:

LUAD miRNA and mRNA expression profiles were downloaded from TCGA database and then differential analysis was used to identify the target miRNA. Target gene for the miRNA was obtained via prediction using 3 bioinformatics databases and intersection with the differentially expressed mRNAs searched from TCGA-LUAD. Then, qRT-PCR and western blot were used to validate the expression of miR-196b and AQP4. Dual-luciferase reporter assay was performed to confirm the targeting relationship between miR-196b and AQP4. Transwell assay was used to investigate the migration and invasion of LUAD cells.

Results:

MiR-196b was screened out by differential and survival analyses, and the downstream target gene AQP4 was identified. In LUAD, miR-196b was highly expressed while AQP4 was poorly expressed. Besides, overexpression of miR-196b promoted cell invasion and migration, while overexpression of AQP4 had negative effects. Moreover, the results of the dual-luciferase reporter assay suggested that AQP4 was a direct target of miR-196b. In addition, we also found that overexpressing AQP4 could suppress the promotive effect of miR-196b on cancer cell invasion and migration.

Conclusion:

MiR-196b promotes the invasion and migration of LUAD cells by down-regulating AQP4, which helps us find new molecular targeted therapies for LUAD.

RabGEF1 functions as an oncogene in U251 glioblastoma cells and is involved in regulating AKT and Erk pathways

BACKGROUND

RabGEF1 is a guanine-nucleotide exchange factor for RAB-5, which plays an oncogenic role in certain human cancers. However, the function of RabGEF1 in glioma has not been studied. Here, we report that the down-regulation of RabGEF1 inhibits the proliferation and metastasis, and induces autophagy of U251 glioblastoma cells.

METHODS

The expression of RabGEF1 in glioma and normal tissues were measured by immunohistochemistry. Four siRNAs targeting different sites of RabGEF1 were conducted and the interference efficiencies were verified by qRT-PCR assay. Western blot was used to detect the expression of interest proteins. Cell proliferation was detected using CCK-8 and clone formation assay. Cell migration and invasion were analyzed by scratch assay and transwell assay, respectively. Flow cytometry was used to detect cell cycle distribution and apoptosis.

RESULTS

RabGEF1 was significantly up-regulated in human glioma tissues. RabGEF1 knockdown reduced cell viability, induced cell cycle arrest and apoptosis in U251 cells. Cell migration and invasion were also inhibited when RabGEF1 silencing. Mechanism studies showed that Cyclin D1 and CDK4/6 were significantly down-regulated when RabGEF1 silencing. p53 and caspase mediated apoptotic pathway was activated by down-regulation of RabGEF1. Moreover, RabGEF1 knockdown also induced autophagy in glioma cells. The investigation of AKT and Erk pathways suggested that phosphorylated AKT, p70S6K and phosphorylated Erk were all decreased when RabGEF1 silencing.

CONCLUSION

In conclusion, our data suggest that RabGEF1 is up-regulated in human glioma and down-regulation of RabGEF1 inhibited cell proliferation and metastasis, and induced autophagy of U251 glioblastoma cells, which might be mediated by inactivation of AKT and Erk signaling pathways.

Combined Systematic Review and Transcriptomic Analyses of Mammalian Aquaporin Classes 1 to 10 as Biomarkers and Prognostic Indicators in Diverse Cancers

Aquaporin (AQP) channels enable regulated transport of water and solutes essential for fluid homeostasis, but they are gaining attention as targets for anticancer therapies. Patterns of AQP expression and survival rates for patients were evaluated by systematic review (PubMed and Embase) and transcriptomic analyses of RNAseq data (Human Protein Atlas database). Meta-analyses confirmed predominantly negative associations between AQP protein and RNA expression levels and patient survival times, most notably for AQP1 in lung, breast and prostate cancers; AQP3 in esophageal, liver and breast cancers; and AQP9 in liver cancer. Patterns of AQP expression were clustered for groups of cancers and associated with risk of death. A quantitative transcriptomic analysis of AQP1-10 in human cancer biopsies similarly showed that increased transcript levels of AQPs 1, 3, 5 and 9 were most frequently associated with poor survival. Unexpectedly, increased AQP7 and AQP8 levels were associated with better survival times in glioma, ovarian and endometrial cancers, and increased AQP11 with better survival in colorectal and breast cancers. Although molecular mechanisms of aquaporins in pathology or protection remain to be fully defined, results here support the hypothesis that overexpression of selected classes of AQPs differentially augments cancer progression. Beyond fluid homeostasis, potential roles for AQPs in cancers (suggested from an expanding appreciation of their functions in normal tissues) include cell motility, membrane process extension, transport of signaling molecules, control of proliferation and apoptosis, increased mechanical compliance, and gas exchange. AQP expression also has been linked to differences in sensitivity to chemotherapy treatments, suggesting possible roles as biomarkers for personalized treatments. Development of AQP pharmacological modulators, administered in cancer-specific combinations, might inspire new interventions for controlling malignant carcinomas.

Glioblastoma Stem Cell-Derived Exosomes Enhance Stemness and Tumorigenicity of Glioma Cells by Transferring Notch1 Protein

Exosomes contain plenty of bioactive information, playing an important role in intercellular communication by transfer their bioactive molecular contents to recipient cells. Glioblastoma stem cells (GSCs) and non-GSC glioma cells coexist in GBM microenvironment; GSC-released exosomes contain intracellular signaling molecules, which may affect the biological phenotypes of recipient cells. However, whether GSC exosomes could affect the biological phenotype of non-GSC glioma cells has not yet been defined. To explore whether GSC exosomes could reprogramme non-GSC glioma cells into GSCs and its possible mechanism involved, non-GSC glioma cells were treated with GSCs released exosomes; the potential mechanisms of action were studied with RNA interference, Notch inhibitors and Western blot analysis. The proliferation, neurosphere formation, invasive capacities, and tumorigenicity of non-GSC glioma cells were increased significantly after GSC exosome treatment; Notch1 signaling pathway was activated in GSCs; Notch1 protein was highly enriched in GSC exosomes; Notch1 signaling pathway and stemness-related protein expressions were increased in GSC exosome treated non-GSC glioma cells and these cell generated tumor tissues; Notch1 protein expression in GSCs and their exosomes, and the neurosphere formation of GSCs were decreased by Notch1 RNA interference; Notch1 signaling pathway protein and stemness protein expressions were decreased in GSC exosome treated non-GSC glioma cells by Notch1 RNA interference and Notch inhibitors. The findings in this study indicated that GSC exosomes act as information carriers, mediated non-GSC glioma cell dedifferentiation into GSCs by delivering Notch1 protein through Notch1 signaling activation, and enhanced stemness and tumorigenicity of non-GSC glioma cells.

Gamabufotalin induces a negative feedback loop connecting ATP1A3 expression and the AQP4 pathway to promote temozolomide sensitivity in glioblastoma cells by targeting the amino acid Thr794

Objectives

Temozolomide (TMZ) is one of the most commonly used clinical drugs for glioblastoma (GBM) treatment, but its drug sensitivity needs to be improved. Gamabufotalin (CS‐6), the primary component of the traditional Chinese medicine “ChanSu,” was shown to have strong anti‐cancer activity. However, more efforts should be directed towards reducing its toxicity or effective treatment doses.

Methods

Target fishing experiment, Western blotting, PCR, confocal immunofluorescence and molecular cloning techniques were performed to search for possible downstream signalling pathways. In addition, GBM xenografts were used to further determine the potential molecular mechanisms of the synergistic effects of CS‐6 and TMZ in vivo.

Results

Mechanistic research revealed a negative feedback loop between ATP1A3 and AQP4 through which CS‐6 inhibited GBM growth and mediated the synergistic treatment effect of CS‐6 and TMZ. In addition, by mutating potential amino acid residues of ATP1A3, which were predicted by modelling and docking to interact with CS‐6, we demonstrated that abrogating hydrogen bonding of the amino acid Thr794 interferes with the activation of ATP1A3 by CS‐6 and that the Thr794Ala mutation directly affects the synergistic treatment efficacy of CS‐6 and TMZ.

Conclusions

As the main potential target of CS‐6, ATP1A3 activation critically depends on the hydrogen bonding of Thr794 with CS‐6. The combination of CS‐6 and TMZ could significantly reduce the therapeutic doses and promote the anti‐cancer efficacy of CS‐6/TMZ monotherapy.

Temozolomide has anti-tumor effects through the phosphorylation of cPLA2 on glioblastoma cells

Temozolomide is an alkylating agent used as the first line of treatment for glioblastoma. However, chemoresistance to temozolomide is common in glioma patients. In addition, there are likely many unknown mechanisms for the anti-tumor effects of temozolomide. It is known that an alkylating agent, sulfur mustard, activates cytosolic phospholipase A₂ (cPLA₂) releasing arachidonic acid to suppress tumors. The present study was performed to elucidate the involvement of cPLA₂ in the anti-tumor mechanisms of temozolomide. In three glioblastoma cell lines (GL261, U251MG and T98G), we performed several evaluations including cell viability, cell migration and apoptosis, to study temozolomide-induced anti-tumor effects. Further, we evaluated tumor size in the murine orthotropic glioblastoma model after oral administration of temozolomide. Finally, we investigated the phosphorylation of cPLA₂ in GL261 cells treated with temozolomide, and clarified whether phosphorylation of cPLA₂ affects cell growth. Temozolomide suppressed cell growth and cell migration in glioblastoma cells in vitro and showed anti-tumor effect in the murine orthotopic glioblastoma model in vivo. Furthermore, temozolomide increased phosphorylation of cPLA_2, which was associated with suppression of cell growth. However, in MGMT high-expressing glioblastoma T98G cells, temozolomide could not suppress cell growth or cause phosphorylation of cPLA_2. These findings indicate that temozolomide suppressed cell growth partly by phosphorylation of cPLA₂ in glioblastoma cells. In addition, because temozolomide did not cause phosphorylation of cPLA₂ in MGMT high-expressing glioblastoma T98G cells, phosphorylation of cPLA₂ may be caused by DNA alkylation of temozolomide.

Dysfunction of 67-kDa Laminin Receptor Disrupts BBB Integrity via Impaired Dystrophin/AQP4 Complex and p38 MAPK/VEGF Activation Following Status Epilepticus

Status epilepticus (SE, a prolonged seizure activity) impairs brain-blood barrier (BBB) integrity, which results in secondary complications following SE. The non-integrin 67-kDa laminin receptor (67-kDa LR) plays a role in cell adherence to laminin (a major glycoprotein component in basement membrane), and participates laminin-mediated signaling pathways including p38 mitogen-activated protein kinase (p38 MAPK). Thus, we investigated the role of 67-kDa LR in SE-induced vasogenic edema formation in the rat piriform cortex (PC). SE diminished 67-kDa LR expression, but increased laminin expression, in endothelial cells accompanied by the reduced SMI-71 (a rat BBB barrier marker) expression. Astroglial 67-kDa LR expression was also reduced in the PC due to massive astroglial loss. 67-kDa LR neutralization led to serum extravasation in the PC concomitant with the reduced SMI-71 expression. 67-kDa LR neutralization also decreased expressions of dystrophin and aquaporin-4 (AQP4). In addition, it increased p38 MAPK phosphorylation and expressions of vascular endothelial growth factor (VEGF), laminin and endothelial nitric oxide synthase (eNOS), which were abrogated by SB202190, a p38 MAPK inhibitor. Therefore, our findings indicate that 67-kDa LR dysfunction may disrupt dystrophin-AQP4 complex, which would evoke vasogenic edema formation and subsequent laminin over-expression via activating p38 MAPK/VEGF axis.

Synergistic anticancer effect of acteoside and temozolomide-based glioblastoma chemotherapy

Temozolomide (TMZ) is an alkylating agent commonly used as a first‑line treatment for high‑grade glioblastoma. However, TMZ has short half‑life and frequently induces tumor resistance, which can limit its therapeutic efficiency. In the present study, it was hypothesized that combined treatment with TMZ and acteoside has synergistic effects in glioblastoma therapy. Using cell viability and wound‑healing assays, it was determined that this treatment regimen reduced cell viability and migration to a greater extent than either TMZ or acteoside alone. Following previous reports that TMZ affected autophagy in glioma cells, the present study examined the effects of TMZ + acteoside combination treatment on apoptosis and autophagy. The TMZ + acteoside combination treatment increased the cleavage of caspase‑3 and levels of B‑cell lymphoma 2 (Bcl‑2)‑associated X protein and phosphorylated p53, and decreased the level of Bcl‑2. The combination treatment increased microtubule‑associated protein 1 light chain 3 and apoptosis‑related gene expression. It was also determined that TMZ + acteoside induced apoptosis and autophagy through the mitogen‑activated protein kinase signaling pathway. These findings suggest that acteoside has beneficial effects on TMZ‑based glioblastoma therapy.

Water Homeostasis and Cell Volume Maintenance and Regulation

From early unicellular organisms that formed in salty water environments to complex organisms that live on land away from water, cells have had to protect a homeostatic internal environment favorable to the biochemical reactions necessary for life. In this chapter, we will outline what steps were necessary to conserve the water within our cells and how mechanisms have evolved to maintain and regulate our cellular and organismal volume. We will first examine whole body water homeostasis and the relationship between kidney function, regulation of blood pressure, and blood filtration in the process of producing urine. We will then discuss how the composition of the lipid-rich bilayer affects its permeability to water and salts, and how the cell uses this differential to drive physiological and biochemical cellular functions. The capacity to maintain cell volume is vital to epithelial transport, neurotransmission, cell cycle, apoptosis, and cell migration. Finally, we will wrap up the chapter by discussing in some detail specific channels, cotransporters, and exchangers that have evolved to facilitate the movement of cations and anions otherwise unable to cross the lipid-rich bilayer and that are involved in maintaining or regulating cell volume.

High expression of glutamate-ammonia ligase is associated with unfavorable prognosis in patients with ovarian cancer

Glutamate-ammonia ligase (GLUL), which is also called GS (glutamine synthetase), is the enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia in an ATP-dependent reaction. Here, we found higher expression of GLUL in the ovarian cancer patients was associated with worse disease-free survival (DFS) and overall survival (OS). In addition, GLUL was heterogeneously expressed in various ovarian cancer cells. The mRNA and protein expression levels of GLUL in NIH:OVCAR-3 and ES-2 cells were obviously higher than that in the other types of ovarian cancer cells. Knockdown of GLUL in NIH:OVCAR-3 or ES-2 cells could significantly decrease the proliferation ability. Furthermore, GLUL knockdown markedly inhibited the p38 MAPK signaling pathway in NIH:OVCAR-3 or ES-2 cells. Our findings suggest that decreasing expression of GLUL may be a new approach that can be used for ovarian cancer treatment.

Molecular Determinants of Malignant Brain Cancers: From Intracellular Alterations to Invasion Mediated by Extracellular Vesicles

Malignant glioma cells invade the surrounding brain parenchyma, by migrating along the blood vessels, thus promoting cancer growth. The biological bases of these activities are grounded in profound alterations of the metabolism and the structural organization of the cells, which consequently acquire the ability to modify the surrounding microenvironment, by altering the extracellular matrix and affecting the properties of the other cells present in the brain, such as normal glial-, endothelial- and immune-cells. Most of the effects on the surrounding environment are probably exerted through the release of a variety of extracellular vesicles (EVs), which contain many different classes of molecules, from genetic material to defined species of lipids and enzymes. EV-associated molecules can be either released into the extracellular matrix (ECM) and/or transferred to neighboring cells: as a consequence, both deep modifications of the recipient cell phenotype and digestion of ECM components are obtained, thus causing cancer propagation, as well as a general brain dysfunction. In this review, we first analyze the main intracellular and extracellular transformations required for glioma cell invasion into the brain parenchyma; then we discuss how these events may be attributed, at least in part, to EVs that, like the pawns of a dramatic chess game with cancer, open the way to the tumor cells themselves.