NFAT2-HDAC1 signaling contributes to the malignant phenotype of glioblastoma

Comprehensive understanding of glioblastoma molecular phenotypes: classification, characteristics, and transition

Among central nervous system-associated malignancies, glioblastoma (GBM) is the most common and has the highest mortality rate. The high heterogeneity of GBM cell types and the complex tumor microenvironment frequently lead to tumor recurrence and sudden relapse in patients treated with temozolomide. In precision medicine, research on GBM treatment is increasingly focusing on molecular subtyping to precisely characterize the cellular and molecular heterogeneity, as well as the refractory nature of GBM toward therapy. Deep understanding of the different molecular expression patterns of GBM subtypes is critical. Researchers have recently proposed tetra fractional or tripartite methods for detecting GBM molecular subtypes. The various molecular subtypes of GBM show significant differences in gene expression patterns and biological behaviors. These subtypes also exhibit high plasticity in their regulatory pathways, oncogene expression, tumor microenvironment alterations, and differential responses to standard therapy. Herein, we summarize the current molecular typing scheme of GBM and the major molecular/genetic characteristics of each subtype. Furthermore, we review the mesenchymal transition mechanisms of GBM under various regulators.

An NFAT1-C3a-C3aR Positive Feedback Loop in Tumor-Associated Macrophages Promotes a Glioma Stem Cell Malignant Phenotype

Extensive infiltration by tumor-associated macrophages (TAM) in combination with myeloid-derived suppressor cells constitute the immunosuppressive microenvironment and promote the malignant phenotype of gliomas. The aggressive mesenchymal (MES)-subtype glioma stem cells (GSC) are prominent in the immunosuppressive microenvironment of gliomas. However, the underlying immune-suppressive mechanisms are still unknown. The current study showed that the antitumor immune microenvironment was activated in glioma in Nfat1-/- mice, suggesting induction of the immune-suppressive microenvironment by nuclear factor of activated T cells-1 (NFAT1). In TAMs, NFAT1 could upregulate the transcriptional activity of complement 3 (C3) and increase the secretion of C3a, which could then bind to C3aR and promote M2-like macrophage polarization by activating TIM-3. Simultaneously, C3a/C3aR activated the Ca2+-NFAT1 pathway, forming a positive feedback loop for the M2-like polarization of TAMs, which further promoted the MES transition of GSCs. Finally, disruption of this feedback loop using a C3aR inhibitor significantly inhibited glioma growth both in vitro and in vivo. The current study demonstrated that a NFAT1-C3a-C3aR positive feedback loop induces M2-like TAMs and further promotes the malignant phenotype of GSCs, which might be the potential therapeutic target for glioma.

USP7-mediated JUND suppresses RCAN2 transcription and elevates NFATC1 to enhance stem cell property in colorectal cancer

Cancer stem cells (CSCs) encompass a subset of highly aggressive tumor cells that are involved in tumor initiation and progression. This study investigates the function of regulator of calcineurin 2 (RCAN2) in the stem cell property in colorectal cancer (CRC). By analyzing four GEO datasets, we obtained RCAN2 as a stemness-related gene in CRC. RCAN2 was poorly expressed in CRC tissues and cells, especially in CSCs. RCAN2 restoration reduced calcineurin activity and promoted phosphorylation and degradation of nuclear factor of activated T cells 1 (NFATC1) protein, leading to reduced stemness of CSCs. JunD proto-oncogene (JUND), whose protein level was increased in CRC samples and CRC stem cells, bound to RCAN2 and suppressed its transcription. The abundant ubiquitin specific peptidase 7 (USP7) in CSCs enhanced JUND protein stability through deubiquitination modification. Lentivirus-mediated knockdown of USP7 or JUND also blocked the calcineurin-NFATC1 signaling and reduced the protein levels of stemness-related proteins. Moreover, the USP7 knockdown weakened the colony/sphere formation ability as well as the tumorigenicity of CSCs, and it reduced the CSC content in xenograft tumors. However, further restoration of JUND rescued the stemness of the CSCs. Overall, this study demonstrates that USP7-mediated JUND suppresses RCAN2 transcription and activates NFATC1 to enhance stem cell property in CRC. 1. RCAN2 is poorly expressed in CRC tissues and cells and especially in CSCs. 2. RCAN2 reduces stemness of CSCs by blocking calcineurin-NFATC1 signal transduction. 3. JUND binds to RCAN2 promoter to suppresses RCAN2 transcription. 4. USP7 enhances JUND protein stability via deubiquitination modification. 5. Downregulation of USP7 or JUND restores RCAN2 level and suppresses stemness of CSCs.

NFAT signaling dysregulation in cancer: Emerging roles in cancer stem cells

The nuclear factor of activated T cells (NFAT) was first identified as a transcriptional regulator of activated T cells. The NFAT family is involved in the development of tumors. Furthermore, recent evidence reveals that NFAT proteins regulate the development of inflammatory and immune responses. New discoveries have also been made about the mechanisms by which NFAT regulates cancer progression through cancer stem cells (CSC). Here, we discuss the role of the NFAT family in the immune system and various cancer types.

SPI1-mediated MIR222HG transcription promotes proneural-to-mesenchymal transition of glioma stem cells and immunosuppressive polarization of macrophages

Background: Glioma stem cells (GSCs) are a key factor in glioblastoma (GBM) development and treatment resistance. GSCs can be divided into the mesenchymal (MES) and proneural (PN) subtypes, and these two subtypes of GSCs can undergo interconversion under certain conditions. MES GSCs have higher malignancy and radioresistance and are closely associated with an immunosuppressive microenvironment. Long noncoding RNAs (lncRNAs) play a broad role in GBM, while the role of GSCs subtype remains unknown. Methods: We performed RNA sequencing to explore the lncRNA expression profile in MES- and PN-subtype GBM tissues. The biological function of a host gene-MIR222HG-in GBM development was confirmed in vitro and in vivo. Specifically, RNA sequencing, RNA pulldown, mass spectrometry, RIP, ChIP, luciferase reporter assays and Co-IP were performed. Results: MIR222HG, the expression of which can be induced by SPI1, has high levels in MES GBM tissues. Functionally, we demonstrated that MIR222HG promotes the MES transition and radioresistance in GSCs in vivo and in vitro. Mechanistically, MIR222HG can bind to the YWHAE/HDAC5 complex to promote the MES transition of GSCs through H4 deacetylation. Moreover, cotranscribed miR221 and miR222 can be delivered to macrophages via exosomes to target SOCS3, causing immunosuppressive polarization. Finally, PLX-4720 sensitivity is associated with SPI1 expression and acts on MES GSCs to enhance radiosensitivity. Conclusions: This study demonstrates that targeting SPI1 to block transcription of the MIR222HG cluster helps to reduce radioresistance and combat the immunosuppressive microenvironment in GBM. PLX-4720 is a potential GBM drug and radiosensitizer.

HDAC1 mediates epithelial-mesenchymal transition and promotes cancer cell invasion in glioblastoma

Glioblastoma multiforme (GBM) is one of the most malignant tumors of the central nervous system, and its treatment has always been a difficult clinical problem. Here, we evaluated HDAC1 expression patterns and their effect on prognosis based on GBM cases from TCGA and CGGA databases. Expression was compared between GBM samples and normal controls. High HDAC1 expression was found to be an indicator of poor prognosis in glioblastoma. We also established a protein-protein interaction network to explore HDAC1-related interacting proteins, including the epithelial-mesenchymal transition (EMT)-related protein VIM, which is closely associated with HDAC1. Consistently, functional enrichment analysis showed that several GBM tissues with high HDAC1 were enriched in the expression of cancer markers, such as those involved in glycolysis, hypoxia, inflammation, and some signaling pathways. Next, this study analyzed the effect of HDAC1 on invasive ability and the EMT signaling pathway in GBM cells in vitro. The results showed that an HDAC1 inhibitor (RGFP109) could inhibit the EMT process in glioma cells in vitro, thereby affecting the invasion and migration of cells. Similar results were obtained based on in vivo studies. Our data suggest that HDAC1 has the potential to be a powerful prognostic biomarker, which might provide a basis for developing therapeutic targets for GBM.

Transcriptional Profiling of a Patient-Matched Cohort of Glioblastoma (IDH-Wildtype) for Therapeutic Target and Repurposing Drug Identification

Glioblastoma (GBM) is the most prevalent and aggressive adult brain tumor. Despite multi-modal therapies, GBM recurs, and patients have poor survival (~14 months). Resistance to therapy may originate from a subpopulation of tumor cells identified as glioma-stem cells (GSC), and new treatments are urgently needed to target these. The biology underpinning GBM recurrence was investigated using whole transcriptome profiling of patient-matched initial and recurrent GBM (recGBM). Differential expression analysis identified 147 significant probes. In total, 24 genes were validated using expression data from four public cohorts and the literature. Functional analyses revealed that transcriptional changes to recGBM were dominated by angiogenesis and immune-related processes. The role of MHC class II proteins in antigen presentation and the differentiation, proliferation, and infiltration of immune cells was enriched. These results suggest recGBM would benefit from immunotherapies. The altered gene signature was further analyzed in a connectivity mapping analysis with QUADrATiC software to identify FDA-approved repurposing drugs. Top-ranking target compounds that may be effective against GSC and GBM recurrence were rosiglitazone, nizatidine, pantoprazole, and tolmetin. Our translational bioinformatics pipeline provides an approach to identify target compounds for repurposing that may add clinical benefit in addition to standard therapies against resistant cancers such as GBM.

Expression, Significance, and Correlation of Histone Deacetylase 1/RE-1 Silencing Transcription Factor and Neuronal Markers in Glioma

BACKGROUND

Inducing the differentiation of glioma cells into neuron-like cells may be an effective strategy to combat glioma. The histone deacetylase 1/RE-1 silencing transcription factor (HDAC1/REST) complex regulates the expression of multiple neuronal genes. In this study, we analyzed the presence and significance of this regulatory effect in glioma based on bioinformatics methods.

METHODS

The Human Protein Atlas database was used to obtain immunohistochemical staining images. The Gene Expression Profiling Interactive Analysis and Chinese Glioma Genome Atlas databases were used to analyze the expression of HDAC1/REST and neuronal markers in glioma, their effects on survival, and the association between HDAC1/REST and the expression of neuronal markers and stem cell markers. The differentially expressed genes between the high and low HDAC1/REST groups were explored. The Database for Annotation, Visualization and Integrated Discovery database was used for gene ontology and kyoto encyclopedia of genes and genomes pathway enrichment analysis.

RESULTS

The results showed that the expression of HDAC1 and REST increased with the grade of glioma, while the expression of neuronal markers decreased with the grade of glioma. High expression of HDAC1/REST and low expression of neuronal markers were associated with poor prognosis. HDAC1/REST expression was negatively correlated with the expression of neuronal markers, and positively correlated with the expression of neural stem cell markers. The genes up-regulated in the high HDAC1/REST group were mainly related to extracellular matrix and inflammation, and the down-regulated genes were mainly related to synapsis.

CONCLUSIONS

This study suggested that HDAC1/REST may be involved in maintaining the malignant phenotype of glioma cells and the stem cell status of glioma stem cells by inhibiting the expression of neuronal markers, which promote the progression of glioma.

Circular RNA circPTPRF promotes the progression of GBM via sponging miR-1208 to up-regulate YY1

Glioblastoma (GBM) is the most common primary malignant tumor in the brain, and its robust proliferation and invasion abilities reduce the survival time of patients. Circular RNAs (circRNAs) play an essential role in various tumors, such as regulating tumor cell proliferation, apoptosis, invasion, metastasis, and other progressive phenotypes through different mechanisms. Finding novel circRNAs may significantly contribute to the prognosis of GBM and provide the basis for the targeted therapy of GBM. In this study, we found circPTPRF is a novel circRNA that has never been studied, which was highly expressed in GBM and is closely related to poor patient prognoses. After knockdown or overexpression in glioma cell lines (U87 and LN229) and glioma stem cells (GSCs), we identified that circPTPRF could promote proliferation, invasion, and neurospheres formation abilities of GBM via in vitro and in vivo experiments. Mechanisms, miR-1208 was confirmed as a target of circPTPRF, and miR-1208 can also target the 3’UTR of YY1, and they were proved by luciferase reporter, western blotting (WB), qPCR and RNA immunoprecipitation (RIP) assays. The following rescue experiments demonstrated that circPTPRF was a miR-1208 sponge for upregulating YY1 expression to promote proliferation, invasion and neurosphere formation abilities of GBM in vitro. In conclusion, the circPTPRF/miR-1208/YY1 axis can regulate GBM progression. CircPTPRF may play an essential role in GBM diagnosis and prognostic prediction and be an important molecular target for GBM therapy.

Identification and validation of SNHG gene signature to predict malignant behaviors and therapeutic responses in glioblastoma

Glioblastoma (GBM) patients exhibit high mortality and recurrence rates despite multimodal therapy. Small nucleolar RNA host genes (SNHGs) are a group of long noncoding RNAs that perform a wide range of biological functions. We aimed to reveal the role of SNHGs in GBM subtypes, cell infiltration into the tumor microenvironment (TME), and stemness characteristics. SNHG interaction patterns were determined based on 25 SNHGs and systematically correlated with GBM subtypes, TME and stemness characteristics. The SNHG interaction score (SNHGscore) model was generated to quantify SNHG interaction patterns. The high SNHGscore group was characterized by a poor prognosis, the mesenchymal (MES) subtype, the infiltration of suppressive immune cells and a differentiated phenotype. Further analysis indicated that high SNHGscore was associated with a weaker response to anti-PD-1/L1 immunotherapy. Tumor cells with high SNHG scores were more sensitive to drugs targeting the EGFR and ERK-MAPK signaling pathways. Finally, we assessed SNHG interaction patterns in multiple cancers to verify their universality. This is a novel and comprehensive study that provides targeted therapeutic strategies based on SNHG interactions. Our work highlights the crosstalk and potential clinical utility of SNHG interactions in cancer therapy.

PIAS1 Alleviates Hepatic Ischemia-Reperfusion Injury in Mice through a Mechanism Involving NFATc1 SUMOylation

Recently, attentions have come to the alleviatory effect of protein inhibitor of activated STAT1 (PIAS1) in hepatic ischemia-reperfusion injury (HIRI), but the underlying molecular mechanistic actions remain largely unknown, which were illustrated in the present study. Microarray-based analysis predicted a possible regulatory mechanism involving the PIAS1/NFATc1/HDAC1/IRF-1/p38 MAPK signaling axis in HIRI. Then, growth dynamics of hypoxia/reoxygenation- (H/R-) exposed hepatocytes and liver injury of HIRI-like mice were delineated after the alteration of the PIAS1 expression. We validated that PIAS1 downregulation occurred in H/R-exposed hepatocytes and HIRI-like mice, while the expression of NFATc1, HDAC1, and IRF-1 and phosphorylation levels of p38 were increased. PIAS1 inactivated p38 MAPK signaling by inhibiting HDAC1-mediated IRF-1 through NFATc1 SUMOylation, thereby repressing the inflammatory response and apoptosis of hepatocytes in vitro, and alleviated liver injury in vivo. Collectively, the NFATc1/HDAC1/IRF-1/p38 MAPK signaling axis is highlighted as a promising therapeutic target for potentiating hepatoprotective effects of PIAS1 against HIRI.

TOPK Affects Autophagy of Skin Squamous Cell Carcinoma by Regulating NF-KB Pathway through HDAC1

Objective

To explore the effect and potential mechanism of T-LAK cell-originated protein kinase (TOPK) on autophagy in cutaneous squamous cell carcinoma (cSCC).

Methods

Human cSCC cancer tissue and paracancerous tissue samples were collected clinically; immunohistochemistry was used to detect the expression of TOPK, nuclear factor κB p65 (NF-κB p65), phosphorylated nuclear factor κB inhibitor α (p-IκBα), Beclin-1, and microtubule-associated protein 1 light chain 3 (LC3) in cSCC tissue; and immunofluorescence was adopted to detect the coexpression of NF-κB p65, p-IκBα, and TOPK in cSCC tissue. After TOPK silencing or overexpression, SCL-1 and A431 cells were treated with PDTC and 3-MA, respectively. RT-qPCR and Western Blot were used to detect the mRNA and protein expressions of histone deacetylase 1 (HDAC1) in TOPK-silenced/overexpressing cells. Western Blot was performed to detect the protein expressions of NF-κB p65, p-p65, IκBα, p-IκBα, Beclin-1, and LC3 in each group. Transwell and scratch healing experiments were used to detect the ability of cells to invade and migrate. The formation of autophagosomes in each group was observed by TEM.

Results

Compared with adjacent tissues, TOPK, NF-κB p65, p-IκBα, Beclin-1, and LC3 were highly expressed in cSCC cancer tissues; TOPK and NF-κB p65 were coexpressed; and TOPK and p-IκBα were expressed in cSCC cancer tissues both increased. The mRNA and protein levels of TOPK in human cSCC cells were significantly higher than those in human normal skin HaCaT cells. After TOPK knockout, the expression of HDAC1, p-IκBα/IκBα, NF-κB p65, p-p65, Beclin-1, LC3II/I proteins, cell invasion, and migration abilities were significantly reduced, and fewer autophagosomes were observed. Treatment with PDTC and 3-MA significantly downregulated NF-κB pathway protein activity and autophagy level and reduced cell migration and invasion ability.

Conclusion

TOPK promotes the malignant progression of cSCC by upregulating HDAC1 to activate the NF-κB pathway and promote autophagy.

Loss of deubiquitylase USP2 triggers development of glioblastoma via TGF-β signaling

Glioblastoma (GBM) is the most aggressive primary brain tumor as one of the deadliest cancers. The TGF-β signaling acts as an oncogenic factor in GBM, and plays vital roles in development of GBM. SMAD7 is a major inhibitor of TGF-β signaling, while the deubiquitination of SMAD7 has been poorly studied in GBM. Here, we found USP2 as a new prominent candidate that could regulate SMAD7 stability. USP2 was lost in GBM, leading to the poor prognosis in patients. Moreover, aberrant DNA methylation mediated by DNMT3A induced the low expression of USP2 in GBM. USP2 depletion induced TGF-β signaling and progression of GBM. In contrast, overexpressed USP2 suppressed TGF-β signaling and GBM development. Specifically, USP2 interacted with SMAD7 and prevented SMAD7 ubiquitination. USP2 directly cleaved Lys27- and Lys48-linked poly-ubiquitin chains of SMAD7, and Lys27-linked poly-ubiquitin chains of SMAD7 K185 mediated the recruitment of SMAD7 to HERC3, which regulated Lys63-linked poly-ubiquitination of SMAD7. Moreover, we demonstrated that the DNMT3A inhibitor SGI-1027 induced USP2, suppressed TGF-β signaling and GBM development. Thus, USP2 repressed development of GBM by inhibition TGF-β signaling pathway via the deubiquitination of SMAD7.

Comprehensive Analysis of the Differential Expression and Prognostic Value of Histone Deacetylases in Glioma

Gliomas are the most common and aggressive malignancies of the central nervous system. Histone deacetylases (HDACs) are important targets in cancer treatment. They regulate complex cellular mechanisms that influence tumor biology and immunogenicity. However, little is known about the function of HDACs in glioma. The Oncomine, Human Protein Atlas, Gene Expression Profiling Interactive Analysis, Broad Institute Cancer Cell Line Encyclopedia, Chinese Glioma Genome Atlas, OmicShare, cBioPortal, GeneMANIA, STRING, and TIMER databases were utilized to analyze the differential expression, prognostic value, and genetic alteration of HDAC and immune cell infiltration in patients with glioma. HDAC1/2 were considerable upregulated whereas HDAC11 was significantly downregulated in cancer tissues. HDAC1/2/3/4/5/7/8/11 were significantly correlated with the clinical glioma stage. HDAC1/2/3/10 were strongly upregulated in 11 glioma cell lines. High HDCA1/3/7 and low HDAC4/5/11 mRNA levels were significantly associated with overall survival and disease-free survival in glioma. HDAC1/2/3/4/5/7/9/10/11 are potential useful biomarkers for predicting the survival of patients with glioma. The functions of HDACs and 50 neighboring genes were primarily related to transcriptional dysregulation in cancers and the Notch, cGMP-PKG, and thyroid hormone signaling pathways. HDAC expression was significantly correlated with the infiltration of B cells, CD4⁺ T cells, CD8⁺ T cells, macrophages, neutrophils, and dendritic cells in glioma. Our study indicated that HDACs are putative precision therapy targets and prognostic biomarkers of survival in glioma patients.

The role of protein acetylation in carcinogenesis and targeted drug discovery

Protein acetylation is a reversible post-translational modification, and is involved in many biological processes in cells, such as transcriptional regulation, DNA damage repair, and energy metabolism, which is an important molecular event and is associated with a wide range of diseases such as cancers. Protein acetylation is dynamically regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs) in homeostasis. The abnormal acetylation level might lead to the occurrence and deterioration of a cancer, and is closely related to various pathophysiological characteristics of a cancer, such as malignant phenotypes, and promotes cancer cells to adapt to tumor microenvironment. Therapeutic modalities targeting protein acetylation are a potential therapeutic strategy. This article discussed the roles of protein acetylation in tumor pathology and therapeutic drugs targeting protein acetylation, which offers the contributions of protein acetylation in clarification of carcinogenesis, and discovery of therapeutic drugs for cancers, and lays the foundation for precision medicine in oncology.

Comprehensive Analysis of HDAC Family Identifies HDAC1 as a Prognostic and Immune Infiltration Indicator and HDAC1-Related Signature for Prognosis in Glioma

Background: The histone deacetylase (HDAC) family limited accessibility to chromatin containing tumor suppressor genes by removing acetyl groups, which was deemed a path for tumorigenesis. Considering glioma remained one of the most common brain cancers with a dichotomy prognosis and limited therapy responses, HDAC inhibitors were an area of intensive research. However, the expression profiles and prognostic value of the HDACs required more elucidation. Methods: Multiple biomedical databases were incorporated, including ONCOMINE, GEPIA, TCGA, CGGA, GEO, TIMER, cBioPortal, and Metascape, to study expression profiles, prognostic value, immune infiltration, mutation status, and enrichment of HDACs in glioma. STRING and GeneMANIA databases were used to identify HDAC1-related molecules. LASSO regression, Cox regression, Kaplan-Meier plot, and receiver operating characteristic (ROC) analyses were performed for HDAC1-related signature construction and validation. Results: HDAC1 was significantly overexpressed in glioma, while HDAC11 was downregulated in glioblastoma. Except for HDAC 6/9/10, the HDAC family expression was significantly associated with glioma grade. Most of the HDAC family also correlated with glioma genetic mutations. Higher HDAC1 expression level predicted more dismal overall survival (OS) (p < 0.0001) and disease-free survival (DFS) (p < 0.0001), but a higher level of HDAC11 held more favorable OS (p = 2.1e-14) and DFS (p = 4.8e-08). HDAC4 displayed the highest mutation ratio, at 2.6% of the family. The prognostic value of HDAC1 was validated with ROC achieving 0.70, 0.77, 0.75, and 0.80 as separability for 1-, 3-, 5-, and 10-years OS predictions in glioma, respectively. Moreover, HDAC1 expression positively correlated with neutrophil (r = 0.60, p = 2.88e-47) and CD4⁺ T cell infiltration (r = 0.52, p = 3.96e-35) in lower-grade glioma. The final HDAC1-related signature comprised of FKBP3, HDAC1 (Hazard Ratio:1.49, 95%Confidence Interval:1.20-1.86), PHF21A, RUNX1T1, and RBL1, and was verified by survival analysis (p < 0.0001) and ROC with 0.80, 0.84, 0.83, and 0.88 as separability for 1-, 3-, 5-, and 10-years OS predictions, respectively. The signature was enriched in chromatin binding. Conclusion: HDAC family was of clinical significance for glioma. Most of the HDAC family significantly correlated with the glioma grade, IDH1 mutation, and 1p/19q codeletion. HDAC1 was both a prognostic and immune infiltration indicator and a central component of the HDAC1-related signature for precise prognosis prediction in glioma.

Nonredundant, isoform-specific roles of HDAC1 in glioma stem cells

Glioblastoma (GBM) is characterized by an aberrant yet druggable epigenetic landscape. One major family of epigenetic regulators, the histone deacetylases (HDACs), are considered promising therapeutic targets for GBM due to their repressive influences on transcription. Although HDACs share redundant functions and common substrates, the unique isoform-specific roles of different HDACs in GBM remain unclear. In neural stem cells, HDAC2 is the indispensable deacetylase to ensure normal brain development and survival in the absence of HDAC1. Surprisingly, we find that HDAC1 is the essential class I deacetylase in glioma stem cells, and its loss is not compensated for by HDAC2. Using cell-based and biochemical assays, transcriptomic analyses, and patient-derived xenograft models, we find that knockdown of HDAC1 alone has profound effects on the glioma stem cell phenotype in a p53-dependent manner. We demonstrate marked suppression in tumor growth upon targeting of HDAC1 and identify compensatory pathways that provide insights into combination therapies for GBM. Our study highlights the importance of HDAC1 in GBM and the need to develop isoform-specific drugs.

RCAN1.4 suppresses the osteosarcoma growth and metastasis via interfering with the calcineurin/NFAT signaling pathway

•

Protein level of RCAN1.4 in osteosarcoma specimens was lower than that of chondroma.

•

RCAN1.4 loss promoted osteosarcoma growth, migration and invasion.

•

RCAN1.4-calcineurin/NFAT pathway regulated the osteosarcoma growth and metastasis.

Calcipressin-1, also known as a regulator of calcineurin 1 (RCAN1), is one of the families of endogenous regulators of calcineurin activation and can specifically constrain the activity of calcineurin, but its function in osteosarcoma is still unknown. Firstly, we examined the protein level of RCAN1 in osteosarcoma specimens was lower than that of chondroma specimens. RCAN1.4 rather than RCAN1.1 had a higher endogenous protein level in six osteosarcoma cell lines by western blot. Further, we created stable RCAN1.4-deficient 143B and Hos cells using CRISPR-Cas9. RCAN1.4 loss promoted tumor growth in subcutaneous xenograft models. RCAN1.4 knockdown promoted tumor metastases to the lungs using intravenous metastasis models. Furthermore, we found that higher activity of calcineurin in RCAN1.4-deficient cells enhanced the nuclear translocation of NFATc1 to induce the cyclin D1 and MMPs expression. In addition, RCAN1.4 overexpression restrained osteosarcoma cell growth and invasion and inhibited the activity of calcineurin. Finally, we discovered that conditioned medium (20%) derived from RCAN1.4-deficient cells significantly promoted osteoclastogenesis, indicating Receptor Activator of Nuclear factor κB (RANK) signaling activation during osteosarcoma metastasis. In conclusion, RCAN1.4 may be a potential therapeutic target for osteosarcoma.

Store-Operated Calcium Channels Control Proliferation and Self-Renewal of Cancer Stem Cells from Glioblastoma

Simple Summary

Glioblastoma is a high-grade primary brain tumor that contains a subpopulation of cells called glioblastoma stem cells, which are responsible for tumor initiation, growth and recurrence after treatment. Recent transcriptomic studies have highlighted that calcium pathways predominate in glioblastoma stem cells. Calcium channels have the ability to transduce signals from the microenvironment and are therefore ideally placed to control cellular behavior. Using multiple approaches, we demonstrate in five different primary cultures, previously derived from surgical specimens, that glioblastoma stem cells express store-operated channels (SOC) that support calcium entry into these cells. Pharmacological inhibition of SOC dramatically reduces cell proliferation and stem cell self-renewal in these cultures. By identifying SOC as a critical mechanism involved in the maintenance of the stem cell population in glioblastoma, our study will contribute to the framework for the identification of new therapies against this deadly tumor.

Abstract

Glioblastoma is the most frequent and deadly form of primary brain tumors. Despite multimodal treatment, more than 90% of patients experience tumor recurrence. Glioblastoma contains a small population of cells, called glioblastoma stem cells (GSC) that are highly resistant to treatment and endowed with the ability to regenerate the tumor, which accounts for tumor recurrence. Transcriptomic studies disclosed an enrichment of calcium (Ca²⁺) signaling transcripts in GSC. In non-excitable cells, store-operated channels (SOC) represent a major route of Ca²⁺ influx. As SOC regulate the self-renewal of adult neural stem cells that are possible cells of origin of GSC, we analyzed the roles of SOC in cultures of GSC previously derived from five different glioblastoma surgical specimens. Immunoblotting and immunocytochemistry experiments showed that GSC express Orai1 and TRPC1, two core SOC proteins, along with their activator STIM1. Ca²⁺ imaging demonstrated that SOC support Ca²⁺ entries in GSC. Pharmacological inhibition of SOC-dependent Ca²⁺ entries decreased proliferation, impaired self-renewal, and reduced expression of the stem cell marker SOX2 in GSC. Our data showing the ability of SOC inhibitors to impede GSC self-renewal paves the way for a strategy to target the cells considered responsible for conveying resistance to treatment and tumor relapse.

Identification of an epigenetic prognostic signature for patients with lower-grade gliomas

INTRODUCTION

Glioma is the most common malignant primary brain tumor with survival outcome for patients with lower-grade gliomas (LGGs) being quite variable. Epigenetic modifications in LGGs appear tightly linked to patient clinical outcomes but are not commonly used as clinical tools.

AIMS

We aimed to derive an epigenetic enzyme gene signature for LGGs that would allow for improved clinical risk stratification.

RESULTS

The study employed transcriptomic data of 711 lower-grade gliomas from three publically available data sets. Based on least absolute shrinkage and selection operator (LASSO) Cox regression analysis, we discovered a 13-gene epigenetic signature that strongly predicts poor overall survival in LGGs. The robust prediction ability for survival was further verified in two independent validation cohorts. The signature was also significantly associated with malignant molecular signatures including wild-type IDH, unmethylated MGMT promoter, and non-codeletion of 1p19q together with linkage to multiple oncogenic pathways. Interestingly, our results showed that immune infiltration of MDSCs together with mRNA expression of immune inhibition biomarkers was also positively correlated with the epigenetic signature. Lastly, we confirmed the oncogenic role of SMYD2 in glioma tumor cells in functional assays.

CONCLUSIONS

We report a novel epigenetic gene signature that harbors robust survival prediction value for LGG patients that is tightly linked to activation of multiple oncogenic pathways.

Epigenetic targeting of SLC30A3 by HDAC1 is related to the malignant phenotype of glioblastoma

The epigenetic abnormality is believed as a major driver for cancer initiation. Histone modification plays a vital role in tumor formation and progression. Particularly, alteration in histone acetylation has been highly associated with gene expression, cell cycle, as well as carcinogenesis. By analyzing glioblastoma (GBM)-related microarray from the GEO database and conducting chromatin immunoprecipitation-sequencing (ChIP-seq), we discovered that solute carrier family 30 member 3 (SLC30A3), a super enhancer (SE)-regulated factor, was significantly reduced in GBM tissues. Furthermore, histone deacetylase 1 (HDAC1), overexpressed in GBM tissues, could inhibit SLC30A3 expression by promoting histone H3K27ac deacetylation modification of the SE region of SLC30A3. Our functional validation revealed that SLC30A3 can inhibit the growth and metastatic spread of GBM cells in vitro and in vivo, and can activate the MAPK signaling pathway to promote apoptosis of GBM cells. Moreover, overexpression of HDAC1 resulted in a significant increase in DNA replication activity, a significant decline in apoptosis and cell cycle arrest in GBM cells. In a word, these findings indicate that combined epigenetic targeting of SLC30A3 by HDAC1 and SE is potentially therapeutically feasible in GBM.

Hypoxia-induced PLOD1 overexpression contributes to the malignant phenotype of glioblastoma via NF-κB signaling

Procollagen lysyl hydroxylase 1 (PLOD1) is highly expressed in malignant tumors such as esophageal squamous cell carcinoma, gastric cancer, and colorectal cancer. Bioinformatics analysis revealed that PLOD1 is associated with the progression of GBM, particularly the most malignant mesenchymal subtype (MES). Moreover, in the TCGA and CGGA datasets, the mean survival time of patients with high PLOD1 expression was significantly shorter than that of patients with low expression. The clinical samples confirmed this result. Therefore, we aimed to investigate the effect of PLOD1 on the development of mesenchymal GBM in vitro and in vivo and its possible mechanisms. Molecular experiments were conducted on the patient-derived glioma stem cells and found that PLOD1 expressed higher in tumor tissues and cancer cell lines of patients with GBM, especially in the MES. PLOD1 also enhanced tumor viability, proliferation, migration, and promoted MES transition while inhibited apoptosis. Tumor xenograft results also indicated that PLOD1 overexpression significantly promotes malignant behavior of tumors. Mechanistically, bioinformatics analysis further revealed that PLOD1 expression was closely associated with the NF-κB signaling pathway. Besides, we also found that hypoxic environments also enhanced the tumor-promoting effects of PLOD1. In conclusion, overexpression of PLOD1 may be an important factor in the enhanced invasiveness and MES transition of GBM. Thus, PLOD1 is a potential treatment target for mesenchymal GBM or even all GBM.

Calcium Channels in Adult Brain Neural Stem Cells and in Glioblastoma Stem Cells

The brain of adult mammals, including humans, contains neural stem cells (NSCs) located within specific niches of which the ventricular-subventricular zone (V-SVZ) is the largest one. Under physiological conditions, NSCs proliferate, self-renew and produce new neurons and glial cells. Several recent studies established that oncogenic mutations in adult NSCs of the V-SVZ are responsible for the emergence of malignant primary brain tumors called glioblastoma. These aggressive tumors contain a small subpopulation of cells, the glioblastoma stem cells (GSCs), that are endowed with proliferative and self-renewal abilities like NSCs from which they may arise. GSCs are thus considered as the cells that initiate and sustain tumor growth and, because of their resistance to current treatments, provoke tumor relapse. A growing body of studies supports that Ca²⁺ signaling controls a variety of processes in NSCs and GSCs. Ca²⁺ is a ubiquitous second messenger whose fluctuations of its intracellular concentrations are handled by channels, pumps, exchangers, and Ca²⁺ binding proteins. The concerted action of the Ca²⁺ toolkit components encodes specific Ca²⁺ signals with defined spatio-temporal characteristics that determine the cellular responses. In this review, after a general overview of the adult brain NSCs and GSCs, we focus on the multiple roles of the Ca²⁺ toolkit in NSCs and discuss how GSCs hijack these mechanisms to promote tumor growth. Extensive knowledge of the role of the Ca²⁺ toolkit in the management of essential functions in healthy and pathological stem cells of the adult brain should help to identify promising targets for clinical applications.

The U2AF2 /circRNA ARF1/miR-342-3p/ISL2 feedback loop regulates angiogenesis in glioma stem cells

BACKGROUND

Glioma is the most common and lethal primary brain tumor in adults, and angiogenesis is one of the key factors contributing to its proliferation, aggressiveness, and malignant transformation. However, the discovery of novel oncogenes and the study of its molecular regulating mechanism based on circular RNAs (circRNAs) may provide a promising treatment target in glioma.

METHODS

Bioinformatics analysis, qPCR, western blotting, and immunohistochemistry were used to detect the expression levels of ISL2, miR-342-3p, circRNA ARF1 (cARF1), U2AF2, and VEGFA. Patient-derived glioma stem cells (GSCs) were established for the molecular experiments. Lentiviral-based infection was used to regulate the expression of these molecules in GSCs. The MTS, EDU, Transwell, and tube formation assays were used to detect the proliferation, invasion, and angiogenesis of human brain microvessel endothelial cells (hBMECs). RNA-binding protein immunoprecipitation, RNA pull-down, dual-luciferase reporter, and chromatin immunoprecipitation assays were used to detect the direct regulation mechanisms among these molecules.

RESULTS

We first identified a novel transcription factor related to neural development. ISL2 was overexpressed in glioma and correlated with poor patient survival. ISL2 transcriptionally regulated VEGFA expression in GSCs and promoted the proliferation, invasion, and angiogenesis of hBMECs via VEGFA-mediated ERK signaling. Regarding its mechanism of action, cARF1 upregulated ISL2 expression in GSCs via miR-342-3p sponging. Furthermore, U2AF2 bound to and promoted the stability and expression of cARF1, while ISL2 induced the expression of U2AF2, which formed a feedback loop in GSCs. We also showed that both U2AF2 and cARF1 had an oncogenic effect, were overexpressed in glioma, and correlated with poor patient survival.

CONCLUSIONS

Our study identified a novel feedback loop among U2AF2, cARF1, miR-342-3p, and ISL2 in GSCs. This feedback loop promoted glioma angiogenesis, and could provide an effective biomarker for glioma diagnosis and prognostic evaluation, as well as possibly being used for targeted therapy.

Chidamide Inhibits Glioma Cells by Increasing Oxidative Stress via the miRNA-338-5p Regulation of Hedgehog Signaling

Objective

Chidamide has a broad spectrum of antitumor activity but its function on glioma remains unknown. The increase of reactive oxygen species (ROS) and reactive nitrogen species (RNS) may control glioma risk by promoting its apoptosis and necrosis. Hedgehog pathway is crucial to glioma cell proliferation and controls ROS production. We aimed to explore the effects of chidamide on the levels of miR-338-5p (glioma cell inhibitor), which may regulate Hedgehog signaling, resulting in the changes of RNS. Materials and Methods. Migration and invasion activities of glioma cells were measured by using the Transwell chamber assay. The expression levels of Sonic Hedgehog (Shh), Indian Hedgehog (Ihh), Desert Hedgehog (Dhh), miR-338-5p, and related molecules were detected by using real-time PCR (RT-PCR) and or Western Blot in U87 and HS683 glioma cells. The effects of chidamide on these molecules were measured by using the miR-338-5p inhibitor or mimics in U87 and HS683 glioma cell lines. ROS and RNS were measured by DCF DA and DAF-FM DA fluorescence. Biomarkers of oxidative stress were measured by using a corresponding kit. Apoptosis and necrosis rates were measured by using flow cytometry.

Results

Chidamide inhibited the growth rate, migration, and invasion of human malignant glioma cells and increased the level of miR-338-5p. miR-338-5p inhibitor or mimics increased or inhibited the growth rate of U87 and HS683 glioma cells. Chidamide inhibited the levels of Shh, Ihh, migration protein E-cadherin, and invading protein MMP-2. The increase in the level of Shh and Ihh led to the reduction in the ROS and RNS levels. miR-338-5p inhibitor or mimics also showed a promoting or inhibitory function for the levels of Shh and Ihh. Furthermore, miR-338-5p mimics and inhibitor inhibited or promoted the migration and invasion of the glioma cells (P < 0.05). Evaluated levels of miR-338-5p increased oxidative stress level and apoptosis and necrosis rate by regulating the levels of biomarkers of oxidative stress (P < 0.05). Evaluated levels of miR-338-5p increased oxidative stress level and apoptosis and necrosis rate by regulating the levels of biomarkers of oxidative stress (

Conclusion

Chidamide inhibits glioma cells by increasing oxidative stress via the miRNA-338-5p regulation of Hedgehog signaling. Chidamide may be a potential drug in the prevention of glioma development.