VAMP8 facilitates cellular proliferation and temozolomide resistance in human glioma cells

VAMP8 as a biomarker and potential therapeutic target for endothelial cell dysfunction in atherosclerosis

BACKGROUND

Endothelial cell dysfunction has a critical role in the pathophysiology of atherosclerosis. This study aims to uncover pivotal genes and pathways linked to endothelial cell dysfunction in atherosclerosis, as well as to ascertain the assumed causal effects and potential mechanisms.

METHODS

Datasets relevant to endothelial cell dysfunction in atherosclerosis were collected and divided into training and validation sets. Following differential analysis, we constructed a protein-protein interaction (PPI) network and a molecular interaction map of common-differentially expressed genes (co-DEGs) with proteins known to be involved in atherosclerotic endothelial cell dysfunction. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genome (KEGG), and Gene Set Enrichment Analysis (GSEA) were also conducted. Moreover, human umbilical vein endothelial cells (HUVECs) were cultured in circumstances characterized by elevated glucose levels to establish a cellular injury model simulating atherosclerotic conditions, and quantitative Polymerase Chain Reaction (qPCR) experiments were conducted to validate the differences of co-DEGs. Subsequently, the Summary-data-based Mendelian Randomization (SMR) method was employed. Additionally, we employed the Western Blot (WB) technique to validate the differential expression of VAMP8. Finally, we identified the differential expression of VAMP8 in the validation set and further validated its differential expression by collecting fresh blood samples from 20 patients with atherosclerosis and 20 healthy individuals.

RESULTS

14 co-DEGs (FABP5, GULP1, COL4A5, VAMP8, FABP4, PFN2, ANGPT2, TFPI2, NUPR1, SULF1, FGF13, BASP1, EPB41L3, and PBK) were identified. SMR analysis confirmed 10 potential causal effect genes: PSRC1, VAMP8, FES, HNRNPUL1, CFDP1, SAP130, MDN1, OPRL1, UTP11, and HOXC4. The qPCR and WB experiments demonstrated that VAMP8 was significantly upregulated in the injured HUVECs group (p < 0.0001). Compared to the control group, VAMP8 was markedly increased in the blood samples of patients with atherosclerosis (p < 0.0001).

CONCLUSIONS

VAMP8 may potentially serve as a pathogenic gene in the process of endothelial dysfunction in atherosclerosis.

Integrative Transcriptome-Wide Association Study With Expression Quantitative Trait Loci Colocalization Identifies a Causal VAMP8 Variant for Nasopharyngeal Carcinoma Susceptibility

Nasopharyngeal carcinoma (NPC) is an Asia-prevalent malignancy, yet its genetic underpinnings remain incompletely understood. Here, a transcriptome-wide association study (TWAS) is conducted on NPC, leveraging gene expression prediction models based on epithelial tissues and genome-wide association study (GWAS) summary statistics from 1577 NPC cases and 6359 controls of southern Chinese descent. The TWAS identifies VAMP8 on chromosome 2p11.2 as a novel susceptibility gene for NPC. Further fine-mapping analyses pinpoint rs1058588, located within VAMP8, as a causal variant through eQTL colocalization, and GWAS analyses across multiple cohorts, achieving GWAS significance (OR = 1.18, P = 3.09 × 10-10). Functional assays demonstrate that VAMP8 exerts a tumorigenic role in NPC, enhancing cell proliferation, migration, and tumor growth. Mechanically, it is uncovered that rs1058588 modulates VAMP8 expression by altering its binding affinity to miR-185. Furthermore, the results show that VAMP8 interacts with DHX9 to facilitate the nuclear recruitment of p65, activating the NF-κB pathway. Collectively, the findings shed light on the genetic predisposition to NPC and underscore the critical role of the functional axis involving miR-185, VAMP8, DHX9, and the NF-κB pathway in NPC pathogenesis.

Vesicle-associated membrane protein 8 knockdown exerts anti-proliferative, pro-apoptotic, anti-autophagic, and pro-ferroptotic effects on colorectal cancer cells by inhibition of the JAK/STAT3 pathway

Vesicle-associated membrane protein 8 (VAMP8), a soluble n-ethylmaleimide-sensitive factor receptor protein, acts as an oncogenic gene in the progression of several malignancies. Nevertheless, the roles and mechanisms of VAMP8 in colorectal cancer (CRC) progression remain unknown. The expression and prognostic significance of VAMP8 in CRC samples were analyzed through bioinformatics analyses. Cell proliferation was detected using CCK-8 and EdU incorporation assays and apoptosis was evaluated via flow cytometry. Western blot analysis was conducted to examine the protein expression. Ferroptosis was evaluated by measurement of iron metabolism, lipid peroxidation, and glutathione (GSH) content. VAMP8 was increased in CRC samples relative to normal samples on the basis of GEPIA and HPA databases. CRC patients with high level of VAMP8 had a worse overall survival. VAMP8 depletion led to a suppression of proliferation and promotion of apoptosis in CRC cells. Additionally, VAMP8 knockdown suppressed beclin1 expression and LC3-II/LC3-I ratio, elevated p62 expression, increased Fe2+, labile iron pool, lipid reactive oxygen species, and malondialdehyde levels, and repressed GSH content and glutathione peroxidase activity. Moreover, VAMP8 knockdown inhibited the activation of janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway in CRC cells. Mechanistically, activation of the JAK/STAT3 pathway by JAK1 or JAK2 overexpression attenuated VAMP8 silencing-mediated anti-proliferative, pro-apoptotic, anti-autophagic, and pro-ferroptotic effects on CRC cells. In conclusion, VAMP8 knockdown affects the proliferation, apoptosis, autophagy, and ferroptosis by the JAK/STAT3 pathway in CRC cells.

SNARE proteins: Core engines of membrane fusion in cancer

Vesicles are loaded with a variety of cargoes, including membrane proteins, secreted proteins, signaling molecules, and various enzymes, etc. Not surprisingly, vesicle transport is essential for proper cellular life activities including growth, division, movement and cellular communication. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediate membrane fusion of vesicles with their target compartments that is fundamental for cargo delivery. Recent studies have shown that multiple SNARE family members are aberrantly expressed in human cancers and actively contribute to malignant proliferation, invasion, metastasis, immune evasion and treatment resistance. Here, the localization and function of SNARE proteins in eukaryotic cells are firstly mapped. Then we summarize the expression and regulation of SNAREs in cancer, and describe their contribution to cancer progression and mechanisms, and finally we propose engineering botulinum toxin as a strategy to target SNAREs for cancer treatment.

Unveiling Atherosclerotic Plaque Heterogeneity and SPP1+/VCAN+ Macrophage Subtype Prognostic Significance Through Integrative Single-Cell and Bulk-Seq Analysis

Background

Dysregulated macrophages are important causes of Atherosclerosis (AS) formation and increased plaque instability, but the heterogeneity of these plaques and the role of macrophage subtypes in plaque instability have yet to be clarified.

Methods

This study integrates single-cell and bulk-seq data to analyze atherosclerotic plaques. Unsupervised clustering was used to reveal distinct plaque subtypes, while survival analysis and gene set variation analysis (GSVA) methods helped in understanding their clinical outcomes. Enrichment of differential expression of macrophage genes (DEMGs) score and pseudo-trajectory analysis were utilized to explore the biological functions and differentiation stages of macrophage subtypes in AS progression. Additionally, CellChat and the BayesPrism deconvolution method were used to elucidate macrophage subtype interaction and their prognostic significance at single-cell resolution. Finally, the expression of biomarkers was validated in mouse experiments.

Results

Three distinct AS plaque subtypes were identified, with cluster 3 plaque subtype being particularly associated with higher immune infiltration and poorer prognosis. The DEMGs score exhibited a significant elevation in three macrophage subtypes (SPP1+/VCAN+ macrophages, IL1B+ macrophages, and FLT3LG+ macrophages), associated with cluster 3 plaque subtype and highlighted the prognostic significance of these subtypes. Activation trajectory of the macrophage subtypes is divided into three states (Pre-branch, Cell fate 1, and Cell fate 2), and Cell fate 2 (SPP1+/VCAN+ macrophages, IL1B+ macrophages, and FLT3LG+ macrophages dominant) exhibiting the highest DEMGs score, distinct interactions with other cell components, and relating to poorer prognosis of ischemic events. This study also uncovered a unique SPP1+/VCAN+ macrophage subtype, rare in quantity but significant in influencing AS progression. Machine learning algorithms identified 10 biomarkers crucial for AS diagnosis. The validation of these biomarkers was performed using Mendelian Randomization analysis and in vitro methods, supporting their relevance in AS pathology.

Conclusion

Our study provides a comprehensive view of AS plaque heterogeneity and the prognostic significance of macrophage subtypes in plaque instability.

VAMP8 suppresses the metastasis via DDX5/β-catenin signal pathway in osteosarcoma

Osteosarcoma is a highly metastatic malignant bone tumor, necessitating the development of new treatments to target its metastasis. Recent studies have revealed the significance of VAMP8 in regulating various signaling pathways in various types of cancer. However, the specific functional role of VAMP8 in osteosarcoma progression remains unclear. In this study, we observed a significant downregulation of VAMP8 in osteosarcoma cells and tissues. Low levels of VAMP8 in osteosarcoma tissues were associated with patients' poor prognosis. VAMP8 inhibited the migration and invasion capability of osteosarcoma cells. Mechanically, we identified DDX5 as a novel interacting partner of VAMP8, and the conjunction of VAMP8 and DDX5 promoted the degradation of DDX5 via the ubiquitin-proteasome system. Moreover, reduced levels of DDX5 led to the downregulation of β-catenin, thereby suppressing the epithelial-mesenchymal transition (EMT). Additionally, VAMP8 promoted autophagy flux, which may contribute to the suppression of osteosarcoma metastasis. In conclusion, our study anticipated that VAMP8 inhibits osteosarcoma metastasis by promoting the proteasomal degradation of DDX5, consequently inhibiting WNT/β-catenin signaling and EMT. Dysregulation of autophagy by VAMP8 is also implicated as a potential mechanism. These findings provide new insights into the biological nature driving osteosarcoma metastasis and highlight the modulation of VAMP8 as a potential therapeutic strategy for targeting osteosarcoma metastasis.

Overcoming chemotherapy resistance in low-grade gliomas: A computational approach

Low-grade gliomas are primary brain tumors that arise from glial cells and are usually treated with temozolomide (TMZ) as a chemotherapeutic option. They are often incurable, but patients have a prolonged survival. One of the shortcomings of the treatment is that patients eventually develop drug resistance. Recent findings show that persisters, cells that enter a dormancy state to resist treatment, play an important role in the development of resistance to TMZ. In this study we constructed a mathematical model of low-grade glioma response to TMZ incorporating a persister population. The model was able to describe the volumetric longitudinal dynamics, observed in routine FLAIR 3D sequences, of low-grade glioma patients acquiring TMZ resistance. We used the model to explore different TMZ administration protocols, first on virtual clones of real patients and afterwards on virtual patients preserving the relationships between parameters of real patients. In silico clinical trials showed that resistance development was deferred by protocols in which individual doses are administered after rest periods, rather than the 28-days cycle standard protocol. This led to median survival gains in virtual patients of more than 15 months when using resting periods between two and three weeks and agreed with recent experimental observations in animal models. Additionally, we tested adaptive variations of these new protocols, what showed a potential reduction in toxicity, but no survival gain. Our computational results highlight the need of further clinical trials that could obtain better results from treatment with TMZ in low grade gliomas.

Inhibition of autophagy; an opportunity for the treatment of cancer resistance

The process of macroautophagy plays a pivotal role in the degradation of long-lived, superfluous, and damaged proteins and organelles, which are later recycled for cellular use. Normal cells rely on autophagy to combat various stressors and insults to ensure survival. However, autophagy is often upregulated in cancer cells, promoting a more aggressive phenotype that allows mutated cells to evade death after exposure to therapeutic treatments. As a result, autophagy has emerged as a significant factor in therapeutic resistance across many cancer types, with underlying mechanisms such as DNA damage, cell cycle arrest, and immune evasion. This review provides a comprehensive summary of the role of autophagy in therapeutic resistance and the limitations of available autophagic inhibitors in cancer treatment. It also highlights the urgent need to explore new inhibitors that can synergize with existing therapies to achieve better patient treatment outcomes. Advancing research in this field is crucial for developing more effective treatments that can help improve the lives of cancer patients.

Integrated molecular analyses of an interferon-γ based subtype with regard to outcome, immune characteristics, and immunotherapy in bladder cancer and experimental verification

This study attempted to explore the role of interferon-γ related genes (IRGs) in the prognosis and immunotherapy of bladder cancer (BC). Based on data downloaded from public databases, molecular subtypes with different IRG expression patterns were determined via nonnegative matrix factorization clustering. On the basis of IRGs, interferon-γ related gene signature (IRGS) was developed through Cox regression analyses. We identified that two molecular subgroups with different outcome and immune profiles. It was proved that IRGS possessed prediction efficiency for BC prognosis. Compared with low IRGS group, high IRGS group was related to less anti-cancer immune cells infiltration, less tumor mutation burden score, more cancer stem cell index, and less benefit from immunotherapy. Differential expression of six model genes (IRF5, LATS2, MTHFD2, VAMP8, HLA-G and PTPN6) was validated between paired tissues by RT-qPCR. This study presents a prognostic model, which could serve as an indicator for the benefit of BC immunotherapy.

Eriocheir sinensis vesicle-associated membrane protein can enhance host cell phagocytosis to resist Spiroplasma eriocheiris infection

Vesicle-associated membrane protein (VAMP) belongs to the receptor protein on the membrane of the secretory transport vesicle and involves in host immune function. The intracellular pathogen Spiroplasma eriocheiris could cause Eriocheir sinensis tremor disease. In a previous study, it was found E. sinensis VAMP (EsVAMP) was differently expressed in S. eriocheiris infection by proteomics analysis. This study mainly aims at the function of EsVAMP in the process of the S. eriocheiris infection. The length of EsVAMP gene was 1681 bp, which contained a 395 bp open reading frame, 90 bp 5'-non-coding region (UTR) and 1277 bp 3'-UTR. The results of qPCR showed that EsVAMP was expressed highly in hemocytes and nerves, followed by gills, intestines and hepatopancreas, and lowly expressed in heart and muscles. EsVAMP in hemocytes was up-regulated after S. eriocheiris infection. After EsVAMP over-expression and S. eriocheiris infection, the RAW264.7 cell morphology and cell viability of the experiment group were significantly better than the control group. Meanwhile, the copy number of S. eriocheiris in the experiment group was significantly lower than that in the control group. After EsVAMP and pCMV-Cre-mCherry were ligated and transfected into RAW264.7 cells, it was found that EsVAMP and lysosome co-localized. Meanwhile, the phagocytosed inactivated S. eriocheiris number and phagocytosed efficiency in RAW264.7 cells were increased significantly. The interference experiment was carried out by synthesizing EsVAMP dsRNA to verify that the EsVAMP transcriptions were successfully suppressed. The S. eriocheiris copy number and the mortality of crab increased significantly after EsVAMP RNAi and S. eriocheiris infection. Meanwhile, the phagocytosed inactivated S. eriocheiris number and phagocytosed efficiency in hemocytes decreased significantly after EsVAMP RNAi and S. eriocheiris infection. These results showed that VAMP was involved in the cell phagocytosis to resist pathogen infection.

Comprehensive transcriptomic characterization reveals core genes and module associated with immunological changes via 1619 samples of brain glioma

Glioma is the most common primary malignant brain tumor with limited treatment options and poor prognosis. To investigate the potential relationships between transcriptional characteristics and clinical phenotypes, we applied weighted gene co-expression network analysis (WGCNA) to construct a free-scale gene co-expression network yielding four modules in gliomas. Turquoise and yellow modules were positively correlated with the most malignant glioma subtype (IDH-wildtype glioblastomas). Of them, genes in turquoise module were mainly involved in immune-related terms and were regulated by NFKB1, RELA, SP1, STAT1 and STAT3. Meanwhile, genes in yellow module mainly participated in cell-cycle and division processes and were regulated by E2F1, TP53, E2F4, YBX1 and E2F3. Furthermore, 14 genes in turquoise module were screened as hub genes. Among them, five prognostic hub genes (TNFRSF1B, LAIR1, TYROBP, VAMP8, and FCGR2A) were selected to construct a prognostic risk score model via LASSO method. The risk score of this immune-related gene signature is associated with clinical features, malignant phenotype, and somatic alterations. Moreover, this signature showed an accurate prediction of prognosis across different clinical and pathological subgroups in three independent datasets including 1619 samples. Our results showed that the high-risk group was characterized by active immune-related activities while the low-risk group enriched in neurophysiological-related pathway. Importantly, the high-risk score of our immune signature predicts an enrichment of glioma-associated microglia/macrophages and less response to immune checkpoint blockade (ICB) therapy in gliomas. This study not only provides new insights into the molecular pathogenesis of glioma, but may also help optimize the immunotherapies for glioma patients.

The Identification of Candidate Biomarkers and Pathways in Atherosclerosis by Integrated Bioinformatics Analysis

BACKGROUND

Atherosclerosis (AS) is a type of yellow substance containing cholesterol in the intima of large and middle arteries, which is mostly caused by fat metabolism disorders and neurovascular dysfunction.

MATERIALS AND METHODS

The GSE100927 data got analyzed to find out the differentially expressed genes (DEGs) using the limma package in R software. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of the DEGs were assessed by the Database for Annotation, Visualization, and Integrated Discovery (DAVID). The Search Tool for the Retrieval of Interacting Genes (STRING) visualized the Protein-Protein Interaction (PPI) network of the aggregated DEGs. GSEA software was used to verify the biological process.

RESULT

We screened 1574 DEGs from 69 groups of atherosclerotic carotid artery and 35 groups of control carotid artery, including 1033 upregulated DEGs and 541 downregulated DEGs. DEGs of AS were chiefly related to immune response, Epstein-Barr virus infection, vascular smooth muscle contraction, and cGMP-PKG signaling pathway. Through PPI networks, we found that the hub genes of AS were PTAFR, VAMP8, RNF19A, VPRBP, RNF217, KLHL42, NEDD4, SH3RF1, UBE2N, PJA2, RNF115, ITCH, SKP1, FBXW4, and UBE2H. GSEA analysis showed that GSE100927 was concentrated in RIPK1-mediated regulated necrosis, FC epsilon receptor fceri signaling, Fceri-mediated NF KB activation, TBC rabgaps, TRAF6-mediated induction of TAK1 complex within TLR4 complex, and RAB regulation of trafficking.

CONCLUSION

Our analysis reveals that immune response, Epstein-Barr virus infection, and so on were major signatures of AS. PTAFR, VAMP8, VPRBP, RNF217, KLHL42, and NEDD4 might facilitate the AS tumorigenesis, which could be new biomarkers for diagnosis and therapy of AS.

Prefused lysosomes cluster on autophagosomes regulated by VAMP8

Lysosome–autophagosome fusion is critical to autophagosome maturation. Although several proteins that regulate this fusion process have been identified, the prefusion architecture and its regulation remain unclear. Herein, we show that upon stimulation, multiple lysosomes form clusters around individual autophagosomes, setting the stage for membrane fusion. The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein on lysosomes—vesicle-associated membrane protein 8 (VAMP8)—plays an important role in forming this prefusion state of lysosomal clusters. To study the potential role of phosphorylation on spontaneous fusion, we investigated the effect of phosphorylation of C-terminal residues of VAMP8. Using a phosphorylation mimic, we observed a decrease of fusion in an ensemble lipid mixing assay and an increase of unfused lysosomes associated with autophagosomes. These results suggest that phosphorylation not only reduces spontaneous fusion for minimizing autophagic flux under normal conditions, but also preassembles multiple lysosomes to increase the fusion probability for resuming autophagy upon stimulation. VAMP8 phosphorylation may thus play an important role in chemotherapy drug resistance by influencing autophagosome maturation.

Knockdown lncRNA CRNDE enhances temozolomide chemosensitivity by regulating autophagy in glioblastoma

Background

The regulatory roles of long non-coding RNA (lncRNA) CRNDE in temozolomide (TMZ) chemoresistance to glioblastoma multiforme (GBM) are still poorly understood. Therefore, the function, characteristics, and possible mechanism of CRNDE in TMZ-induced chemoresistance to GBM were explored.

Methods

Firstly, the expression level of CRNDE in 58 cases of glioma tissue specimens and 30 cases of normal brain tissues were tested by qRT-PCR. Meanwhile, the correlation between CRNDE expression level, the clinicopathological characteristics, and survival time of patients with glioma were analyzed. Then, the CRNDE expression in various glioma cell lines was detected, and CRNDE knockdown cell models were constructed. Subsequently, to explore the effect of CRNDE on chemosensitivity to TMZ, cell viability was detected by the CCK-8 assay and IC₅₀ values, and cell proliferation was detected by cell clone assay and EdU assay, as well as cell survival was detected by apoptosis with flow cytometry under TMZ treatment. Further, the expression of drug-resistance protein ABCG2, autophagy related proteins, and PI3K/Akt/mTOR pathway were measured by western blot or qRT-PCR in TMZ-treated glioma cells. Finally, the mouse tumor xenograft model was established and the tumor volume and weight were measured, and ABCG2 expression was conducted by immunohistochemistry assay.

Results

The integrated results demonstrated lncRNA CRNDE was a poor prognosis factor for GBM patient, which was upregulated in patients who were resistant to TMZ, and closely associated with chemotherapeutic response status to TMZ treatment. Further, functional assays revealed that knockdown of CRNDE could notably reduce glioma cell viability and proliferation, and elevate cell apoptosis to enhance the chemosensitivity to TMZ in vitro and in vivo. Mechanistically, the depression of CRNDE could diminish the expression of LC3 II/I, Beclin1 and Atg5 and increase the p62 expression level to inhibit autophagy due to the activation of PI3K/Akt/mTOR pathway as well as highly correlated with ABCG2 expression.

Conclusions

Overall, the study provided that lncRNA CRNDE is a reliable clinical predictor of outcome and prognosis and a potential biomarker for predicting TMZ treatment response in GBM by modulating the autophagy through PI3K/Akt/mTOR pathway and ABCG2 expression which may be a novel therapeutic target for regulating TMZ sensitivity to GBM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02153-x.

Elucidating the mechanisms of Temozolomide resistance in gliomas and the strategies to overcome the resistance

Temozolomide (TMZ) is a first-choice alkylating agent inducted as a gold standard therapy for glioblastoma multiforme (GBM) and astrocytoma. A majority of patients do not respond to TMZ during the course of their treatment. Activation of DNA repair pathways is the principal mechanism for this phenomenon that detaches TMZ-induced O-6-methylguanine adducts and restores genomic integrity. Current understanding in the domain of oncology adds several other novel mechanisms of resistance such as the involvement of miRNAs, drug efflux transporters, gap junction's activity, the advent of glioma stem cells as well as upregulation of cell survival autophagy. This review describes a multifaceted account of different mechanisms responsible for the intrinsic and acquired TMZ-resistance. Here, we summarize different strategies that intensify the TMZ effect such as MGMT inhibition, development of novel imidazotetrazine analog, and combination therapy; with an aim to incorporate a successful treatment and increased overall survival in GBM patients.

ITGB2 as a prognostic indicator and a predictive marker for immunotherapy in gliomas

PURPOSE

Glioma is the most common primary tumor in the brain, accounting for 81% of intracranial malignancies. Nowadays, cancer immunotherapy has become a novel and revolutionary treatment for patients with advanced, highly aggressive tumors. However, to date, there are no effective biomarkers to reflect the response of glioma patients to immunotherapy. In this study, we aimed to assess the clinical predictive value of ITGB2 in patients with glioma.

METHODS

The correlation between ITGB2 expression levels and glioma progression was explored and validated using data from CGGA, TCGA, GEO datasets, and patient samples from our hospital. Univariate and multivariate cox regression models were developed to determine the predictive role of ITGB2 on the prognosis of patients with glioma. The relationship between ITGB2 and immune activation was then analyzed. Finally, we predicted the immunotherapy response in both high and low ITGB2 expression subgroups.

RESULTS

ITGB2 was significantly elevated in gliomas with higher malignancy and predicted poor prognosis. In multivariate analysis, the hazard ratio for ITGB2 expression (low versus high) was 0.71 with 95% CI (0.59-0.85) (P < 0.001). Furthermore, we found that ITGB2 stratified glioma patients into high and low ITGB2 expression subgroups, exhibiting different clinical outcomes and immune activation status. At last, we demonstrated that glioma patients with high ITGB2 expression levels had better immunotherapy response.

CONCLUSIONS

This study demonstrated ITGB2 as a novel predictor for clinical prognosis and response to immunotherapy in gliomas. Assessing expression levels of ITGB2 is a promising method to discover patients that may benefit from immunotherapy.

VMP1, a novel prognostic biomarker, contributes to glioma development by regulating autophagy

Background

Malignant glioma, especially glioblastoma, is a highly aggressive disease with a dismal prognosis. Vacuole membrane protein 1 (VMP1) is a critical autophagy-associated protein with roles in oncogenesis and tumor progression. However, the contribution of VMP1 to glioma development as well as its prognostic value has not been established.

Methods

The expression of VMP1 and clinicopathologic data for 1996 glioma samples were collected from authoritative public databases to explore its prognostic value. Lentiviral CRISPR-Cas9 gene editing system was performed to deplete VMP1 expression. Apoptosis assays, cell cycle assays, colony formation assays, and EdU incorporation analysis were conducted to validate the biological function of VMP1. Transmission electron microscopy was used to determine the role of VMP1 in regulating autophagy.

Results

VMP1 overexpression was associated with advanced disease and had a poor prognosis in patients with glioma. The depletion of VMP1 by CRISPR-Cas9 gene editing significantly inhibited cell proliferation, increased cell death, and induced cell cycle arrest. Mechanistically, VMP1 knockout blocked autophagic flux and thus sensitized glioma cells to radiotherapy and chemotherapy. Moreover, a nomogram model showed that VMP1 expression has high prognostic value for determining survival in glioma.

Conclusions

Our results provide insights into the pathological and biological functions of VMP1, including its roles in promoting tumor growth and progression, and support its value as a new diagnostic and prognostic biomarker for glioma.

Genotoxic therapy and resistance mechanism in gliomas

Glioma is one of the most common and lethal brain tumors. Surgical resection followed by radiotherapy plus chemotherapy is the current standard of care for patients with glioma. The existence of resistance to genotoxic therapy, as well as the nature of tumor heterogeneity greatly limits the efficacy of glioma therapy. DNA damage repair pathways play essential roles in many aspects of glioma biology such as cancer progression, therapy resistance, and tumor relapse. O6-methylguanine-DNA methyltransferase (MGMT) repairs the cytotoxic DNA lesion generated by temozolomide (TMZ), considered as the main mechanism of drug resistance. In addition, mismatch repair, base excision repair, and homologous recombination DNA repair also play pivotal roles in treatment resistance as well. Furthermore, cellular mechanisms, such as cancer stem cells, evasion from apoptosis, and metabolic reprogramming, also contribute to TMZ resistance in gliomas. Investigations over the past two decades have revealed comprehensive mechanisms of glioma therapy resistance, which has led to the development of novel therapeutic strategies and targeting molecules.

In vitro biomimetic models for glioblastoma-a promising tool for drug response studies

The poor response of glioblastoma to current treatment protocols is a consequence of its intrinsic drug resistance. Resistance to chemotherapy is primarily associated with considerable cellular heterogeneity, and plasticity of glioblastoma cells, alterations in gene expression, presence of specific tumor microenvironment conditions and blood-brain barrier. In an attempt to successfully overcome chemoresistance and better understand the biological behavior of glioblastoma, numerous tri-dimensional (3D) biomimetic models were developed in the past decade. These novel advanced models are able to better recapitulate the spatial organization of glioblastoma in a real time, therefore providing more realistic and reliable evidence to the response of glioblastoma to therapy. Moreover, these models enable the fine-tuning of different tumor microenvironment conditions and facilitate studies on the effects of the tumor microenvironment on glioblastoma chemoresistance. This review outlines current knowledge on the essence of glioblastoma chemoresistance and describes the progress achieved by 3D biomimetic models. Moreover, comprehensive literature assessment regarding the influence of 3D culturing and microenvironment mimicking on glioblastoma gene expression and biological behavior is also provided. The contribution of the blood-brain barrier as well as the blood-tumor barrier to glioblastoma chemoresistance is also reviewed from the perspective of 3D biomimetic models. Finally, the role of mathematical models in predicting 3D glioblastoma behavior and drug response is elaborated. In the future, technological innovations along with mathematical simulations should create reliable 3D biomimetic systems for glioblastoma research that should facilitate the identification and possibly application in preclinical drug testing and precision medicine.

Targeting Cytoprotective Autophagy to Enhance Anticancer Therapies

Autophagy is a highly regulated multi-step process that occurs at the basal level in almost all cells. Although the deregulation of the autophagy process has been described in several pathologies, the role of autophagy in cancer as a cytoprotective mechanism is currently well established and supported by experimental and clinical evidence. Our understanding of the molecular mechanism of the autophagy process has largely contributed to defining how we can harness this process to improve the benefit of cancer therapies. While the role of autophagy in tumor resistance to chemotherapy is extensively documented, emerging data point toward autophagy as a mechanism of cancer resistance to radiotherapy, targeted therapy, and immunotherapy. Therefore, manipulating autophagy has emerged as a promising strategy to overcome tumor resistance to various anti-cancer therapies, and autophagy modulators are currently evaluated in combination therapies in several clinical trials. In this review, we will summarize our current knowledge of the impact of genetically and pharmacologically modulating autophagy genes and proteins, involved in the different steps of the autophagy process, on the therapeutic benefit of various cancer therapies. We will also briefly discuss the challenges and limitations to developing potent and selective autophagy inhibitors that could be used in ongoing clinical trials.

Tumor-associated macrophages based signaling pathway analysis and hub genes identification in glioma

Tumor-associated macrophages (TAMs) play a crucial role in the immune response to many malignancies, but the signaling pathways by which the glioma microenvironment cross-talk with TAMs are poorly understood. The aim of this study was to uncover the potential signaling pathways of the regulation of TAMs and identify candidate targets for therapeutic intervention of glioma through bioinformatics analysis.Chinese Glioma Genome Atlas (CGGA) and The Cancer Genome Atlas (TCGA) datasets were used to download RNA-Seq data and microarray data of human glioma specimen. Differentially expressed genes (DEGs) between CD68-high samples and CD68-low samples were sorted. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the DEGs was conducted. Protein-protein interaction (PPI) network were formed to identify the hub genes.The prognostic value of TAMs in glioma patients was confirmed. A total of 477 specific DEGs were sorted. The signaling pathway was identified in pathway enrichment and the DEGs showed prominent representations of immune response networks in glioma. The hub genes including C3, IL6, ITGB2, PTAFR, TIMP1 and VAMP8 were identified form the PPI network and they were all correlated positively with the expression of CD68 and showed the excellent prognostic value in glioma patients.TAMs can be used as a good prognostic indicator in glioma patients. By analyzing comprehensive bioinformatics data, we uncovered the underlying signaling pathway of the DEGs between glioma patients with high and low expression level of CD68. Furthermore, the 6 hub genes identified were closely associated with TAMs in glioma microenvironment and need further investigation.

Identification and Verification of Immune-Related Gene Prognostic Signature Based on ssGSEA for Osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and adolescence. Multiple immune-related genes have been reported in different cancers. The aim is to identify an immune-related gene signature for the prospective evaluation of prognosis for osteosarcoma patients. In this study, we evaluated the infiltration of immune cells in 101 osteosarcoma patients downloaded from TARGET using the ssGSEA to the RNA-sequencing of these patients, thus, high immune cell infiltration cluster, middle immune cell infiltration cluster and low immune cell infiltration cluster were generated. On the foundation of high immune cell infiltration cluster vs. low immune cell infiltration cluster and normal vs. osteosarcoma, we found 108 common differentially expressed genes which were sequentially submitted to univariate Cox and LASSO regression analysis. Furthermore, GSEA indicated some pathways with notable enrichment in the high- and low-immune cell infiltration cluster that may be helpful in understanding the potential mechanisms. Finally, we identified seven immune-related genes as prognostic signature for osteosarcoma. Kaplan-Meier analysis, ROC curve, univariate and multivariate Cox regression further confirmed that the seven immune-related genes signature was an innovative and significant prognostic factor independent of clinical features. These results of this study offer a means to predict the prognosis and survival of osteosarcoma patients with uncovered seven-gene signature as potential biomarkers.

MSC-AS1 knockdown inhibits cell growth and temozolomide resistance by regulating miR-373-3p/CPEB4 axis in glioma through PI3K/Akt pathway

Long non-coding RNAs (lncRNAs) have been widely reported to regulate the development and chemoresistance of a variety of tumors. Temozolomide (TMZ) is a first-line chemotherapy for treatment of glioma. However, the effect and the regulatory mechanism of lncRNA MSC-AS1 (MSC-AS1) in TMZ-resistant glioma remain unrevealed. Levels of MSC-AS1, microRNA-373-3p (miR-373-3p), and cytoplasmic polyadenylation element binding protein 4 (CPEB4) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). All protein expression was detected by western blot. Cell viability and the half maximal inhibitory concentration (IC₅₀) value of TMZ was assessed by cell counting kit-8 (CCK-8) assay. Cell cloning ability and apoptosis were examined by colony formation and flow cytometry assays, respectively. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were performed to verify the correlation between miR-373-3p and MSC-AS1 or CPEB4. The xenograft models were established to determine the effect of MSC-AS1 in vivo. MSC-AS1 was up-regulated in TMZ-resistant glioma tissues and cells, and glioma patients with high MSC-AS1 expression tend to have lower overall survival rate. MSC-AS1 suppression reduced the IC₅₀ value of TMZ and proliferation, promoted apoptosis and TMZ sensitivity, and affected PI3K/Akt pathway in TMZ-resistant glioma cells. MSC-AS1 acted as miR-373-3p sponge, and miR-373-3p directly targeted CPEB4. Silencing miR-373-3p reversed the promoting effect of MSC-AS1 or CPEB4 knockdown on TMZ sensitivity. Furthermore, MSC-AS1 knockdown inhibited TMZ-resistant glioma growth in vivo by regulating miR-373-3p/CPEB4 axis through PI3K/Akt pathway. Collectively, MSC-AS1 knockdown suppressed cell growth and the chemoresistance of glioma cells to TMZ by regulating miR-373-3p/CPEB4 axis in vitro and in vivo through activating PI3K/Akt pathway.

Bioinformatic Profiling of Prognosis-Related Genes in Malignant Glioma Microenvironment

BACKGROUND Gliomas are the most common primary tumors of the brain and spinal cord. The tumor microenvironment (TME) is the cellular environment in which tumors exist. This study aimed to identify the role of the TME and the effects of genes involved in the TME of malignant glioma. MATERIAL AND METHODS The ESTIMATE algorithms in the R package were used to calculate the immune and stromal scores of samples in the TCGA and GSE4290 datasets. The associations of stromal and immune scores with clinicopathological characteristics and overall survival of malignant glioma patients were assessed by analysis of variance and Kaplan-Meier analysis. Differentially expressed genes (DEGs) were obtained through the median immune and stromal score using the R package "limma". Functional enrichment analysis and the PPI network MCODE were used to analyze DEGs. RESULTS Increased immune and stromal scores were closely related with advanced glioma grade and poor prognosis (all P<0.01). In total, 558 DEGs were found and most were related to tumor prognosis. Functional enrichment analysis showed that DEGs were associated with cell-matrix regulation and immune response. Four hub modules related to tumor angiogenesis, collagen formation, and immune response were found and analyzed. Previously overlooked microenvironment-related genes such as LAMB1, FN1, ACTN1, TRIM, SERPINH1, CYBA, LAIR1, and LILRB2 showed prognostic values in malignant glioma patients. CONCLUSIONS The glioma stromal/immune scores are closely related to glioma grade, histology, and survival time. Some glioma microenvironment-related genes including LAMB1, FN1, ACTN1, TRIM6, SERPINH1, CYBA, LAIR1, and LILRB2 show prognostic values in malignant gliomas and serve as potential biomarkers.

Long non-coding RNA LINC01426 facilitates glioblastoma progression via sponging miR-345-3p and upregulation of VAMP8

Background

Long non-coding RNAs (lncRNAs) has been extensively reported play important roles in regulating the development and progression of cancers, including Glioblastoma (GBM). LINC01426 is a novel lncRNA that has been identified as an oncogenic gene in GBM. Herein, we attempted to elucidate the detailed functions and underlying mechanisms of LINC01426 in GBM.

Methods

LINC01426 expression in GBM cell lines and tissues were detected by quantitative real-time PCR (qRT-PCR). Cell Counting Kit-8 (CCK8) assays, colony formation assays, subcutaneous tumor formation assays were utilized to investigate the biological functions of LINC01426 in GBM. Dual-luciferase reporter assays, RNA immunoprecipitation (RIP) and bioinformatic analysis were performed to determine the underlying mechanisms.

Results

LINC01426 is up-regulated in malignant GBM tissues and cell lines and it is capable to promote GBM cell proliferation and growth. Mechanistically, LINC01426 serves as a molecular sponge to sequester the miR345-3p and thus enhancing the level of VAMP8, an oncogenic coding gene, to promote GBM progression.

Conclusions

Our results revealed the detailed mechanisms of LINC01426 facilitated cell proliferation and growth in GBM and report the clinical value of LINC01426 for GBM prognosis and treatment.

A Humanized Yeast Phenomic Model of Deoxycytidine Kinase to Predict Genetic Buffering of Nucleoside Analog Cytotoxicity

Knowledge about synthetic lethality can be applied to enhance the efficacy of anticancer therapies in individual patients harboring genetic alterations in their cancer that specifically render it vulnerable. We investigated the potential for high-resolution phenomic analysis in yeast to predict such genetic vulnerabilities by systematic, comprehensive, and quantitative assessment of drug–gene interaction for gemcitabine and cytarabine, substrates of deoxycytidine kinase that have similar molecular structures yet distinct antitumor efficacy. Human deoxycytidine kinase (dCK) was conditionally expressed in the Saccharomyces cerevisiae genomic library of knockout and knockdown (YKO/KD) strains, to globally and quantitatively characterize differential drug–gene interaction for gemcitabine and cytarabine. Pathway enrichment analysis revealed that autophagy, histone modification, chromatin remodeling, and apoptosis-related processes influence gemcitabine specifically, while drug–gene interaction specific to cytarabine was less enriched in gene ontology. Processes having influence over both drugs were DNA repair and integrity checkpoints and vesicle transport and fusion. Non-gene ontology (GO)-enriched genes were also informative. Yeast phenomic and cancer cell line pharmacogenomics data were integrated to identify yeast–human homologs with correlated differential gene expression and drug efficacy, thus providing a unique resource to predict whether differential gene expression observed in cancer genetic profiles are causal in tumor-specific responses to cytotoxic agents.

The dual roles of autophagy in gliomagenesis and clinical therapy strategies based on autophagic regulation mechanisms

Autophagy, a self-digestion intracellular catabolic process, plays a crucial role in cellular homeostasis under conditions of starvation, oxidative stress and genotoxic stress. The capability of maintaining homeostasis contributes to preventing malignant behavior in normal cells. Many studies have provided compelling evidence that autophagy is involved in brain tumor recurrence and chemotherapy and radiotherapy resistance. Gliomas, as the primary central nervous system (CNS) tumors, are characterized by rapid, aggressive growth and recurrence and have a poor prognosis and bleak outlook even with modern multimodality strategies involving maximal surgical resection, radiotherapy and alkylating agent-based chemotherapy. Autophagy-associated signaling pathways, such as the extracellular signal-regulated kinase1/2 (ERK1/2) pathway, class I phosphatidylinositol 3-phosphate kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway and nuclear factor kappa-B (NF-κB) pathway, act as tumor suppressors or protect tumor cells against chemotherapy/radiotherapy-induced cytotoxicity in gliomagenesis. Through these pathways, both lethal autophagy and protective autophagy play crucial roles in tumor initiation, chemoresistance and glioma stem cell differentiation. Moreover, lethal autophagy and protective autophagy have been identified as novel therapeutic targets in glioma according to the mechanisms described above. Here, we discuss the multiple impacts of the autophagic response on distinct phases of gliomagenesis and the advanced progress of therapies based on this concept.

Factor Analysis for Bicluster Acquisition (FABIA) revealed vincristine-sensitive transcript pattern of canine transmissible venereal tumors

Chemotherapeutic treatment for Canine transmissible venereal tumor (CTVT) commonly relies on vincristine administration. Since the treatment outcomes can vary among CTVT cases, gaining insight into the tumor cell mechanisms influencing vincristine's potency should render veterinarians novel knowledge to enhance its therapeutic effect. This study aimed to attain such knowledge from a meta-analysis of CTVT mRNA sequencing (mRNA-seq) transcriptome data using Factor Analysis for Bicluster Acquisition (FABIA) biclustering. FABIA biclustering identified 459 genes consistently expressed among mRNA-seq transcription profiling of CTVT samples regressed by vincristine. These genes were also differentially expressed from those of progressive CTVT (FDR ≤ 0.001). Enrichment analysis illustrated the affiliation of these genes with "Antigen presentation" and "Lysosome" GO terms (FDR ≤ 0.05). Several genes in "Lysosome" term involved 5 cell mechanisms-antigen presentation, autophagy, cell-adhesion, lysosomal membrane permeabilization (LMP), and PI3K/mTOR signaling. This study integrated FABIA biclustering in CTVT transcriptome analysis to gain insight into cell mechanisms responsible for vincristine-sensitive characteristics of the tumor, in order to identify new molecular targets augmenting therapeutic effect of vincristine. Interestingly, the analysis indicated LMP targeting by lysosome destabilizing agent-siramesine as the promising vincristine's enhancer for future study. As far as we know, this is the first canine tumor transcriptomic meta-analysis applying FABIA biclustering for the betterment of future CTVT therapy. This study hereby provided an interesting manifestation to acquire such knowledge in other canine neoplasia.

Down-regulation of ABCE1 inhibits temozolomide resistance in glioma through the PI3K/Akt/NF-κB signaling pathway

The ATP binding cassette (ABC) E1 (ABCE1), a member of the ABC family, was originally described as the RNase L inhibitor. Through forming a heterodimer with RNase L, ABCE1 participates in the negative regulation of the 2-5A/RNase L system and thus mediates a wide range of biological functions. Recent evidence has shown the new roles of ABCE1 in tumorigenesis. However, there have been no investigations on the specific effect of ABCE1 on glioma. In the present study, we examined the expression pattern and possible role of ABCE1 in glioma. Our study demonstrated that ABCE1 was up-regulated in glioma tissues and cell lines. Down-regulation of ABCE1 inhibited temozolomide (TMZ) resistance of glioma cells in vitro and in vivo In addition, we found that the PI3K/Akt/NF-κB pathway was involved in ABCE1-mediated chemoresistance of glioma cells. Taken together, our study suggested ABCE1 as a promising target for glioma chemotherapy.

Significance of Vesicle-Associated Membrane Protein 8 Expression in Predicting Survival in Breast Cancer

Purpose

Vesicle-associated membrane protein 8 (VAMP8) is a soluble N-ethylmaleimide-sensitive factor receptor protein that participates in autophagy by directly regulating autophagosome membrane fusion and has been reported to be involved in tumor progression. Nevertheless, the expression and prognostic value of VAMP8 in breast cancer (BC) remain unknown. This study aimed to evaluate the clinical significance and biological function of VAMP8 in BC.

Methods

A total of 112 BC samples and 30 normal mammary gland samples were collected. The expression of VAMP8 was assessed in both BC tissues and normal mammary gland tissues via a two-step immunohistochemical detection method.

Results

The expression of VAMP8 in BC tissues was significantly higher than that in normal breast tissues. Furthermore, increased VAMP8 expression was significantly correlated with tumor size (p=0.007), lymph node metastasis (p=0.024) and recurrence (p=0.001). Patients with high VAMP8 expression had significantly lower cumulative recurrence-free survival and overall survival (p<0.001 for both) than patients with low VAMP8 expression. In multivariate logistic regression and Cox regression analyses, lymph node metastasis and VAMP8 expression were independent prognostic factors for BC.

Conclusion

VAMP8 is significantly upregulated in human BC tissues and can thus be a practical and potentially effective surrogate marker for survival in BC patients.

Exosomes impact survival to radiation exposure in cell line models of nervous system cancer

Radiation is utilized in the therapy of more than 50% of cancer patients. Unfortunately, many malignancies become resistant to radiation over time. We investigated the hypothesis that one method of a cancer cell's ability to survive radiation occurs through cellular communication via exosomes. Exosomes are cell-derived vesicles containing DNA, RNA, and protein. Three properties were analyzed: 1) exosome function, 2) exosome profile and 3) exosome uptake/blockade. To analyze exosome function, we show radiation-derived exosomes increased proliferation and enabled recipient cancer cells to survive radiation in vitro. Furthermore, radiation-derived exosomes increased tumor burden and decreased survival in an in vivo model. To address the mechanism underlying the alterations by exosomes in recipient cells, we obtained a profile of radiation-derived exosomes that showed expression changes favoring a resistant/proliferative profile. Radiation-derived exosomes contain elevated oncogenic miR-889, oncogenic mRNAs, and proteins of the proteasome pathway, Notch, Jak-STAT, and cell cycle pathways. Radiation-derived exosomes contain decreased levels of tumor-suppressive miR-516, miR-365, and multiple tumor-suppressive mRNAs. Ingenuity pathway analysis revealed the most represented networks included cell cycle, growth/survival. Upregulation of DNM2 correlated with increased exosome uptake. To analyze the property of exosome blockade, heparin and simvastatin were used to inhibit uptake of exosomes in recipient cells resulting in inhibited induction of proliferation and cellular survival. Because these agents have shown some success as cancer therapies, our data suggest their mechanism of action could be limiting exosome communication between cells. The results of our study identify a novel exosome-based mechanism that may underlie a cancer cell's ability to survive radiation.

VAMP8, a vesicle-SNARE required for RAB37-mediated exocytosis, possesses a tumor metastasis suppressor function

We previously identified a metastasis suppressor RAB37 small GTPase that regulated exocytosis of tissue inhibitor of metalloproteinases 1 (TIMP1) to suppress lung cancer metastasis. Here, we show that vesicle-associated membrane protein 8 (VAMP8), a v-SNARE (vesicle soluble N-ethylmaleimide-sensitive factor activating protein receptor), interacts with RAB37 and drives the secretion of TIMP1 to inhibit tumor metastases. Confocal and total internal reflection fluorescence microscopic images demonstrated that VAMP8 co-localized with RAB37 and facilitated trafficking of RAB37-TIMP1 vesicles. Reconstitution experiments using tail-vein injection and lung-to-lung metastasis in mice showed that VAMP8 was essential for RAB37-regulated vesicle trafficking of TIMP1 to suppress cancer metastasis. Lung cancer patients with low VAMP8 showed distant metastasis, poor overall survival and progression-free survival. Importantly, multivariate Cox regression analysis indicated that patients with low VAMP8/low RAB37 expression profile showed significantly high risk of death (hazard ratio = 3.42, P < 0.001) even after adjusting for tumor metastasis parameter. Our findings reveal that VAMP8 is a novel v-SNARE crucial for RAB37-mediated exocytic transport of TIMP1 to suppress lung tumor metastasis. VAMP8 possesses a tumor metastasis suppressor function with a prognostic value in lung cancer.

Circular RNA hsa_circ_0008344 regulates glioblastoma cell proliferation, migration, invasion, and apoptosis

BACKGROUND

Recent studies have found circular RNAs (circRNAs) involved in the biological process of cancers. However, little is known about their functional roles in glioblastoma.

METHODS

Human circRNA microarray analysis was performed to screen the expression profile of circRNAs in IDH1 wild-type glioblastoma tissue. The expression of hsa_circ_0008344 in glioblastoma and normal brain samples was quantified by qRT-PCR. Functional experiments were performed to investigate the biological functions of hsa_circ_0008344, including MTT assay, colony formation assay, transwell assay, and cell apoptosis assay.

RESULTS

CircRNA microarray revealed a total of 417 abnormally expressed circRNAs (>1.5-fold, P < .05) in glioblastoma tissue compared with the adjacent normal brain. Hsa_circ_0008344, among the top differentially expressed circRNAs, was significantly upregulated in IDH1 wild-type glioblastoma. Further in vitro studies showed that knockdown of hsa_circ_0008344 suppressed glioblastoma cell proliferation, colony formation, migration, and invasion, but increased cell apoptotic rate.

CONCLUSIONS

Hsa_circ_0008344 is upregulated in glioblastoma and may contribute to the progression of this malignancy.

CPEB4 regulates glioblastoma cell proliferation and predicts poor outcome of patients

OBJECTIVE

Cytoplasmic polyadenylation element binding protein 4 (CPEB4) is a regulator of gene expression at transcriptional level and has been reported to be associated with biological malignancy in cancers. However, little was known about the correlation between CPEB4 and glioblastoma cell proliferation and the prognostic significance in patients. Our aim was to investigate the functional role and prognostic value of CPEB4 in glioblastoma.

PATIENTS AND METHODS

We determined the expression of CPEB4 protein using immunohistochemistry in tissue microarrays containing 278 glioma patients (including 98 primary glioblastomas) and evaluated its association with pathological grades and clinical outcome by univariate and multivariate analyses. And then, lentiviral-mediated RNAi targeting CPEB4 was utilized to study the role of CPEB4 in glioblastoma cell proliferation.

RESULTS

In our cohort, CPEB4 expression was positively related to glioma pathological grade (p < 0.01) and elevated in glioblastoma (p < 0.01). High expression of CPEB4 was associated with significantly poor prognosis, and could be identified as an independent risk factor for overall survival (OS) and progression-free survival (PFS) of glioblastoma patients (hazard ratio (HR) = 1.730, p = 0.014 and HR = 1.877, p = 0.004, respectively). In vitro studies further showed that downregulation of CPEB4 significantly reduced the growth rate of T98G and U251 cells comparing with the controls.

CONCLUSION

Our study indicated that increased expression of CPEB4 in primary glioblastoma is a novel biomarker for predicting poor outcome of patients and suppression of CPEB4 inhibit tumor cell proliferation, suggesting a potential therapeutic target for glioblastoma.

Actin-capping protein CapG is associated with prognosis, proliferation and metastasis in human glioma

Glioma is the most aggressive and malignant primary brain tumor in adults. In the present study, we identified a vital oncoprotein, capping actin protein, gelsolin-like (CapG), and investigated its roles in the prognosis, proliferation and metastasis in glioma. The mRNA and protein levels of CapG were significantly increased in human glioma, and higher CapG expression was an independent prognostic factor for predicting unfavorable prognosis. The expression level of CapG was found to be associated with several common molecular features of glioblastoma (GBM; WHO grade IV glioma) in The Cancer Genome Atlas (TCGA) cohort. When analyzing the prognosis of GBM patients according to these molecular features, we observed that the prognostic value of CapG was affected by amplification of CDK6 or EGFR. However, overexpression of CapG markedly promoted cell growth in vitro, while depletion of CapG significantly inhibited cell proliferation by blocking the cell cycle in G1/S transition. Moreover, CapG manipulation in glioma cell lines U87 and U251 showed CapG-dependent cellular migration and invasiveness. These data suggest that CapG may serve as a prognostic biomarker with potentially important therapeutic implications for glioma.

SNARE proteins in membrane trafficking

SNAREs are the core machinery mediating membrane fusion. In this review, we provide an update on the recent progress on SNAREs regulating membrane fusion events, especially the more detailed fusion processes dissected by well-developed biophysical methods and in vitro single molecule analysis approaches. We also briefly summarize the relevant research from Chinese laboratories and highlight the significant contributions on our understanding of SNARE-mediated membrane trafficking from scientists in China.

All-trans retinoic acid enhances temozolomide-induced autophagy in human glioma cells U251 via targeting Keap1/Nrf2/ARE signaling pathway

The present study evaluated the retinoic acid (RA) enhancement of temozolomide (TMZ) effects on the human glioma cells U251 and explored its underlying molecular mechanism. The cell growth was detected using the MTT assay and the cell cycle was assessed by flow cytometry. Cell apoptosis was analyzed by Annexin V/propidium iodide staining, and the cell morphology was evaluated using transmission electron microscopy (TEM). Additionally, reverse transcription-PCR and western blot analysis were applied to detect the mRNA and protein levels. The RA treatment in combination with TMZ in the human U251 cells further inhibited cells growth, arresting cell cycle progression at the G0/G1 phase, and significantly induced apoptosis of U251 cells. After the RA+TMZ treatment of U251 cells, autophagy associated proteins Beclin 1 and LC3B were significantly increased, and the TEM analysis were consistent with autophagy protein levels. Moreover, Keap1/Nrf2/ARE expression was downregulated significantly, indicating the involvement in the mechanisms that RA treatment could enhance the TMZ effects on U251 cells. RA treatment in combination with TMZ may provide some experimental evidence for the possible effect of RA+TMZ against the growth and the proliferation of glioma cells. Therefore, the RA+TMZ administration may have potential utility for glioblastoma treatment.

Cytoplasmic RAP1 mediates cisplatin resistance of non-small cell lung cancer

Cytotoxic chemotherapy agents (e.g., cisplatin) are the first-line drugs to treat non-small cell lung cancer (NSCLC) but NSCLC develops resistance to the agent, limiting therapeutic efficacy. Despite many approaches to identifying the underlying mechanism for cisplatin resistance, there remains a lack of effective targets in the population that resist cisplatin treatment. In this study, we sought to investigate the role of cytoplasmic RAP1, a previously identified positive regulator of NF-κB signaling, in the development of cisplatin resistance in NSCLC cells. We found that the expression of cytoplasmic RAP1 was significantly higher in high-grade NSCLC tissues than in low-grade NSCLC; compared with a normal pulmonary epithelial cell line, the A549 NSCLC cells exhibited more cytoplasmic RAP1 expression as well as increased NF-κB activity; cisplatin treatment resulted in a further increase of cytoplasmic RAP1 in A549 cells; overexpression of RAP1 desensitized the A549 cells to cisplatin, and conversely, RAP1 depletion in the NSCLC cells reduced their proliferation and increased their sensitivity to cisplatin, indicating that RAP1 is required for cell growth and has a key mediating role in the development of cisplatin resistance in NSCLC cells. The RAP1-mediated cisplatin resistance was associated with the activation of NF-κB signaling and the upregulation of the antiapoptosis factor BCL-2. Intriguingly, in the small portion of RAP1-depleted cells that survived cisplatin treatment, no induction of NF-κB activity and BCL-2 expression was observed. Furthermore, in established cisplatin-resistant A549 cells, RAP1 depletion caused BCL2 depletion, caspase activation and dramatic lethality to the cells. Hence, our results demonstrate that the cytoplasmic RAP1–NF-κB–BCL2 axis represents a key pathway to cisplatin resistance in NSCLC cells, identifying RAP1 as a marker and a potential therapeutic target for cisplatin resistance of NSCLC.

Hypoxia-Mediated Mechanisms Associated with Antiangiogenic Treatment Resistance in Glioblastomas

Glioblastomas (GBMs) are malignant tumors characterized by their vascularity and invasive capabilities. Antiangiogenic therapy (AAT) is a treatment option that targets GBM-associated vasculature to mitigate the growth of GBMs. However, AAT demonstrates transient effects because many patients eventually develop resistance to this treatment. Several recent studies attempt to explain the molecular and biochemical basis of resistance to AAT in GBM patients. Experimental investigations suggest that the induction of extensive intratumoral hypoxia plays a key role in GBM escape from AAT. In this review, we examine AAT resistance in GBMs, with an emphasis on six potential hypoxia-mediated mechanisms: enhanced invasion and migration, including increased expression of matrix metalloproteinases and activation of the c-MET tyrosine kinase pathway; shifts in cellular metabolism, including up-regulation of hypoxia inducible factor-1α's downstream processes and the Warburg effect; induction of autophagy; augmentation of GBM stem cell self-renewal; possible implications of GBM-endothelial cell transdifferentiation; and vasoformative responses, including vasculogenesis, alternative angiogenic pathways, and vascular mimicry. Juxtaposing recent studies on well-established resistance pathways with that of emerging mechanisms highlights the overall complexity of GBM treatment resistance while also providing direction for further investigation.

RLIP76 Depletion Enhances Autophagic Flux in U251 Cells

Our previous study showed that RalA-binding protein 1 (RLIP76) is overexpressed in gliomas and is associated with higher tumour grade and decreased patient survival. Furthermore, RLIP76 downregulation increases chemosensitivity of glioma cells to temozolomide by inducing apoptosis. However, other mechanisms underlying RLIP76-associated chemoresistance are unknown. In this study, we investigated the effect of RLIP76 depletion on autophagy. RLIP76 was knocked down in U251 glioma cells using shRNA and autophagy-related proteins, and PI3K/Akt signalling components were evaluated. RLIP76 depletion significantly increased cell autophagy as demonstrated by a significant increase in LC3 II, autophagy protein 5 (ATG-5), and Beclin1, and a decrease in p62 expression levels. Furthermore, RLIP76 knockdown increased autophagic flux in U251 cells as autolysosome numbers increased relative to autophagosome numbers. Autophagy induced by RLIP76 knockdown resulted in increased apoptosis that was independent of temozolomide treatment. Moreover, RLIP76 knockdown decreased PI3K and Akt activation. RLIP76 depletion also resulted in decreased levels of the anti-apoptotic protein Bcl2. LY294002, a PI3K/Akt pathway inhibitor, led to increased autophagy and apoptosis in U251 RLIP76-depleted cells. Therefore, RLIP76 knockdown increased autophagic flux and apoptosis in U251 glioma cells, possibly through inhibition of the PI3K/Akt pathway. Thus, this study provides a novel mechanism for the role of RLIP76 in glioma pathogenesis and chemoresistance.

SNAP23 promotes the malignant process of ovarian cancer

Background

Ovarian cancer (OC) was the primary malignant gynecological cancer and SNARE protein is closely related with tumor progression. Here, we identified SNAP23, a member of SNARE complex, as a potential oncogene in OC.

Methods

We determined the expression of SNAP23 in OC tissues and explored the clinical significance through bioinformatics analysis. The effects of SNAP23 on OC cell proliferation, migration, invasion, cell cycle and apoptosis were then evaluated in vitro.

Results

SNAP23 is hyper-expressed in OC tumor tissues compared to normal tissues, and increased expression of SNAP23 is associated with a poor progression free survival (HR = 1.24, 95% CI = 1.07–1.44, p = 0.0042). SNAP23 knock down increases cell apoptosis and inhibits cell proliferation, migration and invasion of OC cells. GO analysis reveals that most genes correlated highly with SNAP23 were enriched in metabolic process.

Conclusions

Our data suggest that SNAP23 may serve as an oncogene promoting tumorigenicity of OC cells by decreasing apoptotic process.

Quercetin blocks t-AUCB-induced autophagy by Hsp27 and Atg7 inhibition in glioblastoma cells in vitro

We previously demonstrated that the acquired resistance because of Hsp27 activation weakens the cytotoxic effect of t-AUCB on glioblastoma cells. Since autophagy is regarded as a survival mechanism for cells exposed to cytotoxic agents, the aim of this study is to investigate whether t-AUCB induces autophagy and whether Hsp27 and autophagy are interacted with each other. Our data demonstrated that t-AUCB induces autophagy in glioblastoma cells and regulates multiple autophagy related-gene expression. t-AUCB induces overexpression of Atg7, which is downstream of Hsp27 and participates in the resistance of glioblastoma cells to t-AUCB treatment. Hsp27 inhibitor quercetin suppresses Atg7 expression and strengthens t-AUCB-induced cell death by autophagy blockage. We concluded that combination of quercetin and t-AUCB might be a potential strategy for glioblastoma treatment.

Targeting autophagy to sensitive glioma to temozolomide treatment

Temozolomide (TMZ), an alkylating agent, is widely used for treating primary and recurrent high-grade gliomas. However, the efficacy of TMZ is often limited by the development of resistance. Recently, studies have found that TMZ treatment could induce autophagy, which contributes to therapy resistance in glioma. To enhance the benefit of TMZ in the treatment of glioblastomas, effective combination strategies are needed to sensitize glioblastoma cells to TMZ. In this regard, as autophagy could promote cell survival or autophagic cell death, modulating autophagy using a pharmacological inhibitor, such as chloroquine, or an inducer, such as rapamycin, has received considerably more attention. To understand the effectiveness of regulating autophagy in glioblastoma treatment, this review summarizes reports on glioblastoma treatments with TMZ and autophagic modulators from in vitro and in vivo studies, as well as clinical trials. Additionally, we discuss the possibility of using autophagy regulatory compounds that can sensitive TMZ treatment as a chemotherapy for glioma treatment.

How to train glioma cells to die: molecular challenges in cell death

The five-year survival rate for patients with malignant glioma is less than 10%. Despite aggressive chemo/radiotherapy these tumors have remained resistant to almost every interventional strategy evaluated in patients. Resistance to these agents is attributed to extrinsic mechanisms such as the tumor microenvironment, poor drug penetration, and tumoral heterogeneity. In addition, genetic and molecular examination of these tumors has revealed defective apoptotic regulation, enhanced pro-survival autophagy signaling, and a propensity for necrosis that aids in the adaptation to environmental stress and resistance to treatment. The combination of extrinsic and intrinsic hallmarks in glioma contributes to the multifaceted resistance to traditional anti-tumor agents. Here we describe the biology of the disease relevant to therapeutic resistance, with a specific focus on molecular deregulation of cell death pathways. Emerging studies investigating the targeting of these pathways including BH3 mimetics and autophagy inhibitors that are being evaluated in both the preclinical and clinical settings are discussed. This review highlights the pathways exploited by glioblastoma cells that drive their hallmark pro-survival predisposition and makes therapy development such a challenge.

Role of SNARE proteins in tumourigenesis and their potential as targets for novel anti-cancer therapeutics

The function of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) in cellular trafficking, membrane fusion and vesicle release in synaptic nerve terminals is well characterised. Recent studies suggest that SNAREs are also important in the control of tumourigenesis through the regulation of multiple signalling and transportation pathways. The majority of published studies investigated the effects of knockdown/knockout or overexpression of particular SNAREs on the normal function of cells as well as their dysfunction in tumourigenesis promotion. SNAREs are involved in the regulation of cancer cell invasion, chemo-resistance, the transportation of autocrine and paracrine factors, autophagy, apoptosis and the phosphorylation of kinases essential for cancer cell biogenesis. This evidence highlights SNAREs as potential targets for novel cancer therapy. This is the first review to summarise the expression and role of SNAREs in cancer biology at the cellular level, their interaction with non-SNARE proteins and modulation of cellular signalling cascades. Finally, a strategy is proposed for developing novel anti-cancer therapeutics using targeted delivery of a SNARE-inactivating protease into malignant cells.

No association of VAMP8 gene polymorphisms with glioma in a Chinese Han population

Vesicle-associated membrane protein 8 (VAMP8) gene plays an important role in biological functions like endosomal fusion, sequential granule-to-granule fusion and autophagy. The current research identified VAMP8 acted as a novel oncogene by promoting cell proliferation and therapeutic resistance in glioma. Nevertheless, the association between VAMP8 genes polymorphism and glioma patients has not been well studied. In our study, to explore the association between single nucleotide polymorphisms (SNPs) of VAMP8 gene with glioma risk in the Chinese Han population, we performed a hospital based case-control study (992 cases and 1008 controls). Eight common tagging SNPs of VAMP8 gene were genotyped, while no significant difference in allele or genotype frequency was found between glioma patients and healthy controls. No positive linkage disequilibrium (LD) was detected either. No haplotype distribution was positive. Accordingly, our study suggested that VAMP8 gene variants might not contribute to glioma susceptibility and associated with glioma in the Chinese Han population.