Loss of ATRX suppresses ATM dependent DNA damage repair by modulating H3K9me3 to enhance temozolomide sensitivity in glioma

SPIN1 facilitates chemoresistance and HR repair by promoting Tip60 binding to H3K9me3

The tandem Tudor-like domain-containing protein Spindlin1 (SPIN1) is a transcriptional coactivator with critical functions in embryonic development and emerging roles in cancer. However, the involvement of SPIN1 in DNA damage repair has remained unclear. Our study shows that SPIN1 is recruited to DNA lesions through its N-terminal disordered region that binds to Poly-ADP-ribose (PAR), and facilitates homologous recombination (HR)-mediated DNA damage repair. SPIN1 promotes H3K9me3 accumulation at DNA damage sites and enhances the interaction between H3K9me3 and Tip60, thereby promoting the activation of ATM and HR repair. We also show that SPIN1 increases chemoresistance. These findings reveal a novel role for SPIN1 in the activation of H3K9me3-dependent DNA repair pathways, and suggest that SPIN1 may contribute to cancer chemoresistance by modulating the efficiency of double-strand break (DSB) repair.

Epigenetic regulation of tumor-immune symbiosis in glioma

Glioma is a type of aggressive and incurable brain tumor. Patients with glioma are highly resistant to all types of therapies, including immunotherapies. Epigenetic reprogramming is a key molecular hallmark in tumors across cancer types, including glioma. Mounting evidence highlights a pivotal role of epigenetic regulation in shaping tumor biology and therapeutic responses through mechanisms involving both glioma cells and immune cells, as well as their symbiotic interactions in the tumor microenvironment (TME). In this review, we discuss the molecular mechanisms of epigenetic regulation that impacts glioma cell biology and tumor immunity in both a cell-autonomous and non-cell-autonomous manner. Moreover, we provide an overview of potential therapeutic approaches that can disrupt epigenetic-regulated tumor-immune symbiosis in the glioma TME.

Potential Diagnostic and Clinical Significance of Selected Genetic Alterations in Glioblastoma

Glioblastoma is currently considered the most common and, unfortunately, also the most aggressive primary brain tumor, with the highest morbidity and mortality rates. The average survival of patients diagnosed with glioblastoma is 14 months, and only 2% of patients survive 3 years after surgery. Based on our clinical experience and knowledge from extensive clinical studies, survival is mainly related to the molecular biological properties of glioblastoma, which are of interest to the general medical community. Our study examined a total of 71 retrospective studies published from 2016 through 2022 and available on PubMed that deal with mutations of selected genes in the pathophysiology of GBM. In conclusion, we can find other mutations within a given gene group that have different effects on the prognosis and quality of survival of a patient with glioblastoma. These mutations, together with the associated mutations of other genes, as well as intratumoral heterogeneity itself, offer enormous potential for further clinical research and possible application in therapeutic practice.

Pancreatic Neuroendocrine Tumors: Signaling Pathways and Epigenetic Regulation

Pancreatic neuroendocrine tumors (PNETs) are characterized by dysregulated signaling pathways that are crucial for tumor formation and progression. The efficacy of traditional therapies is limited, particularly in the treatment of PNETs at an advanced stage. Epigenetic alterations profoundly impact the activity of signaling pathways in cancer development, offering potential opportunities for drug development. There is currently a lack of extensive research on epigenetic regulation in PNETs. To fill this gap, we first summarize major signaling events that are involved in PNET development. Then, we discuss the epigenetic regulation of these signaling pathways in the context of both PNETs and commonly occurring-and therefore more extensively studied-malignancies. Finally, we will offer a perspective on the future research direction of the PNET epigenome and its potential applications in patient care.

Histone lactylation-derived LINC01127 promotes the self-renewal of glioblastoma stem cells via the cis-regulating the MAP4K4 to activate JNK pathway

Gliomas are the most prevalent and aggressive brain tumors, exhibiting high proliferation, abnormal glycolysis, and poor prognosis. LncRNAs act as regulatory molecules and play crucial roles in the malignant behaviors of GBM cells, including cell self-renewal. However, the regulatory mechanisms involved are largely unknown. In this study, we performed bioinformatics analysis to explore NF-κB pathway-related lncRNAs. ECAR and qRT-PCR were used to measure the relationship between glycolytic activity and lncRNA expression. Assays such as RIP-PCR and ChIP-PCR were employed to reveal the regulatory mechanisms of the lncRNA. Neurosphere formation and limiting dilution assays were performed to evaluate the self-renewal capacity of GBM cells. In our study, we identified an NF-κB pathway-related lncRNA named LINC01127 in GBM, which was found to be associated with poor progression of GBM. Functionally, the NF-κB pathway promoted warburg effect, which, in turn, induced the lactylation of H3 histone and increased the expression of LINC01127. Consequently, this enhancement of LINC01127 expression led to the promotion of self-renewal in GBM cells. Furthermore, LINC01127 regulated MAP4K4 expression in cis by directly guiding POLR2A to the MAP4K4 promoter regions, thereby leading to JNK pathway activation, and ultimately modulating the self-renewal of GBM cells. Moreover, the activated JNK pathway promoted the phosphorylation of IκBα. Overall, targeting LINC01127-mediated axis impeded orthotopic tumor growth in GBM xenografts. Taken together these results revealed that warburg effect-induced histone lactylation drives NF-κB-related LINC01127 expression, thereby promoting the self-renewal of GBM cells through the MAP4K4/JNK/NF-κB axis, and providing substantial evidence that LINC01127 might provide a novel therapeutic strategy for GBM patients.

Novel sights on therapeutic, prognostic, and diagnostics aspects of non-coding RNAs in glioblastoma multiforme

Glioblastoma Multiforme (GBM) is the primary brain tumor and accounts for 200,000 deaths each year worldwide. The standard therapy includes surgical resection followed by temozolomide (TMZ)-based chemotherapy and radiotherapy. The survival period of GBM patients is only 12-15 months. Therefore, novel treatment modalities for GBM treatment are urgently needed. Mounting evidence reveals that non-coding RNAs (ncRNAs) were involved in regulating gene expression, the pathophysiology of GBM, and enhancing therapeutic outcomes. The combinatory use of ncRNAs, chemotherapeutic drugs, and tumor suppressor gene expression induction might provide an innovative, alternative therapeutic approach for managing GBM. Studies have highlighted the role of Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in prognosis and diagnosis. Dysregulation of ncRNAs is observed in virtually all tumor types, including GBMs. Studies have also indicated the blood-brain barrier (BBB) as a crucial factor that hinders chemotherapy. Although several nanoparticle-mediated drug deliveries were degrading effectively against GBM in vitro conditions. However, the potential to cross the BBB and optimum delivery of oligonucleotide RNA into GBM cells in the brain is currently under intense clinical trials. Despite several advances in molecular pathogenesis, GBM remains resistant to chemo and radiotherapy. Targeted therapies have less clinical benefit due to high genetic heterogeneity and activation of alternative pathways. Thus, identifying GBM-specific prognostic pathways, essential genes, and genomic aberrations provide several potential benefits as subtypes of GBM. Also, these approaches will provide insights into new strategies to overcome the heterogenous nature of GBM, which will eventually lead to successful therapeutic interventions toward precision medicine and precision oncology.

Atrx deletion impairs CGAS/STING signaling and increases sarcoma response to radiation and oncolytic herpesvirus

ATRX is one of the most frequently altered genes in solid tumors, and mutation is especially frequent in soft tissue sarcomas. However, the role of ATRX in tumor development and response to cancer therapies remains poorly understood. Here, we developed a primary mouse model of soft tissue sarcoma and showed that Atrx-deleted tumors were more sensitive to radiation therapy and to oncolytic herpesvirus. In the absence of Atrx, irradiated sarcomas had increased persistent DNA damage, telomere dysfunction, and mitotic catastrophe. Our work also showed that Atrx deletion resulted in downregulation of the CGAS/STING signaling pathway at multiple points in the pathway and was not driven by mutations or transcriptional downregulation of the CGAS/STING pathway components. We found that both human and mouse models of Atrx-deleted sarcoma had a reduced adaptive immune response, markedly impaired CGAS/STING signaling, and increased sensitivity to TVEC, an oncolytic herpesvirus that is currently FDA approved for the treatment of aggressive melanomas. Translation of these results to patients with ATRX-mutant cancers could enable genomically guided cancer therapy approaches to improve patient outcomes.

Functional importance of glucose transporters and chromatin epigenetic factors in Glioblastoma Multiforme (GBM): possible therapeutics

Glioblastoma Multiforme (GBM) is an aggressive brain cancer affecting glial cells and is chemo- and radio-resistant. Glucose is considered the most vital energy source for cancer cell proliferation. During metabolism, hexose molecules will be transported into the cells via transmembrane proteins known as glucose transporter (GLUT). Among them, GLUT-1 and GLUT-3 play pivotal roles in glucose transport in GBM. Knockdown studies have established the role of GLUT-1, and GLUT-3 mediated glucose transport in GBM cells, providing insight into GLUT-mediated cancer signaling and cancer aggressiveness. This review focussed on the vital role of GLUT-1 and GLUT-3 proteins, which regulate glucose transport. Recent studies have identified the role of GLUT inhibitors in effective cancer prevention. Several of them are in clinical trials. Understanding and functional approaches towards glucose-mediated cell metabolism and chromatin epigenetics will provide valuable insights into the mechanism of cancer aggressiveness, cancer stemness, and chemo-resistance in Glioblastoma Multiforme (GBM). This review summarizes the role of GLUT inhibitors, micro-RNAs, and long non-coding RNAs that aid in inhibiting glucose uptake by the GBM cells and other cancer cells leading to the identification of potential therapeutic, prognostic as well as diagnostic markers. Furthermore, the involvement of epigenetic factors, such as microRNAs, in regulating glycolytic genes was demonstrated.

The Chromatin Remodeler ATRX: Role and Mechanism in Biology and Cancer

The alpha-thalassemia mental retardation X-linked (ATRX) syndrome protein is a chromatin remodeling protein that primarily promotes the deposit of H3.3 histone variants in the telomere area. ATRX mutations not only cause ATRX syndrome but also influence development and promote cancer. The primary molecular characteristics of ATRX, including its molecular structures and normal and malignant biological roles, are reviewed in this article. We discuss the role of ATRX in its interactions with the histone variant H3.3, chromatin remodeling, DNA damage response, replication stress, and cancers, particularly gliomas, neuroblastomas, and pancreatic neuroendocrine tumors. ATRX is implicated in several important cellular processes and serves a crucial function in regulating gene expression and genomic integrity throughout embryogenesis. However, the nature of its involvement in the growth and development of cancer remains unknown. As mechanistic and molecular investigations on ATRX disclose its essential functions in cancer, customized therapies targeting ATRX will become accessible.

ATRX, a guardian of chromatin

ATRX (alpha-thalassemia mental retardation X-linked) is one of the most frequently mutated tumor suppressor genes in human cancers, especially in glioma, and recent findings indicate roles for ATRX in key molecular pathways, such as the regulation of chromatin state, gene expression, and DNA damage repair, placing ATRX as a central player in the maintenance of genome stability and function. This has led to new perspectives about the functional role of ATRX and its relationship with cancer. Here, we provide an overview of ATRX interactions and molecular functions and discuss the consequences of its impairment, including alternative lengthening of telomeres and therapeutic vulnerabilities that may be exploited in cancer cells.

Multicenter clinical radiomics-integrated model based on [18F]FDG PET and multi-modal MRI predict ATRX mutation status in IDH-mutant lower-grade gliomas

OBJECTIVES

To develop a clinical radiomics-integrated model based on ¹⁸ F-fluorodeoxyglucose positron emission tomography ([¹⁸F]FDG PET) and multi-modal MRI for predicting alpha thalassemia/mental retardation X-linked (ATRX) mutation status of IDH-mutant lower-grade gliomas (LGGs).

METHODS

One hundred and two patients (47 ATRX mutant-type, 55 ATRX wild-type) diagnosed with IDH-mutant LGGs (CNS WHO grades 1 and 2) were retrospectively enrolled. A total of 5540 radiomics features were extracted from structural MR (sMR) images (contrast-enhanced T1-weighted imaging, CE-T1WI; T2-weighted imaging, and T2WI), functional MR (fMR) images (apparent diffusion coefficient, ADC; cerebral blood volume, CBV), and metabolic PET images ([¹⁸F]FDG PET). The random forest algorithm was used to establish a clinical radiomics-integrated model, integrating the optimal multi-modal radiomics model with three clinical parameters. The predictive effectiveness of the models was evaluated by receiver operating characteristic (ROC) and decision curve analysis (DCA).

RESULTS

The optimal multi-modal model incorporated sMR (CE-T1WI), fMR (ADC), and metabolic ([¹⁸F]FDG) images ([¹⁸F]FDG PET+ADC+ CE-T1WI) with the area under curves (AUCs) in the training and test groups of 0.971 and 0.962, respectively. The clinical radiomics-integrated model, incorporating [¹⁸F]FDG PET+ADC+CE-T1WI, three clinical parameters (KPS, SFSD, and ATGR), showed the best predictive effectiveness in the training and test groups (0.987 and 0.975, respectively).

CONCLUSIONS

The clinical radiomics-integrated model with metabolic, structural, and functional information based on [¹⁸F]FDG PET and multi-modal MRI achieved promising performance for predicting the ATRX mutation status of IDH-mutant LGGs.

KEY POINTS

• The clinical radiomics-integrated model based on [¹⁸F]FDG PET and multi-modal MRI achieved promising performance for predicting ATRX mutation status in LGGs. • The study investigated the value of multicenter clinical radiomics-integrated model based on [¹⁸F]FDG PET and multi-modal MRI in LGGs regarding ATRX mutation status prediction. • The integrated model provided structural, functional, and metabolic information simultaneously and demonstrated with satisfactory calibration and discrimination in the training and test groups (0.987 and 0.975, respectively).

Go-Ichi-Ni-San 2: A potential biomarker and therapeutic target in human cancers

Cancer incidence and mortality are increasing globally, leading to its rising status as a leading cause of death. The Go-Ichi-Ni-San (GINS) complex plays a crucial role in DNA replication and the cell cycle. The GINS complex consists of four subunits encoded by the GINS1, GINS2, GINS3, and GINS4 genes. Recent findings have shown that GINS2 expression is upregulated in many diseases, particularly tumors. For example, increased GINS2 expression has been found in cervical cancer, gastric adenocarcinoma, glioma, non-small cell lung cancer, and pancreatic cancer. It correlates with the clinicopathological characteristics of the tumors. In addition, high GINS2 expression plays a pro-carcinogenic role in tumor development by promoting tumor cell proliferation and migration, inhibiting tumor cell apoptosis, and blocking the cell cycle. This review describes the upregulation of GINS2 expression in most human tumors and the pathway of GINS2 in tumor development. GINS2 may serve as a new marker for tumor diagnosis and a new biological target for therapy.

Basement-Membrane-Related Gene Signature Predicts Prognosis in WHO Grade II/III Gliomas

Gliomas that are classified as grade II or grade III lesions by the World Health Organization (WHO) are highly aggressive, and some may develop into glioblastomas within a short period, thus portending the conferral of a poor prognosis for patients. Previous studies have implicated basement membrane (BM)-related genes in glioma development. In this study, we constructed a prognostic model for WHO grade II/III gliomas in accordance with the risk scores of BM-related genes. Differentially expressed genes (DEGs) in the glioma samples relative to normal samples were screened from the GEO database, and five prognostically relevant BM-related genes, including NELL2, UNC5A, TNC, CSPG4, and SMOC1, were selected using Cox regression analyses for the risk score model. The median risk score was calculated, based on which high- and low-risk groups of patients were generated. The clinical information, pathological information, and risk group were combined to establish a prognostic nomogram. Both the nomogram and risk score model performed well in the independent CGGA cohort. Gene set enrichment analysis (GSEA) and immune profile, drug sensitivity, and tumor mutation burden (TMB) analyses were performed in the two risk groups. A significant enrichment of 'Autophagy-other', 'Collecting duct acid secretion', 'Glycosphingolipid biosynthesis-lacto and neolacto series', 'Valine, leucine, and isoleucine degradation', 'Vibrio cholerae infection', and other pathways were observed for patients with high risk. In addition, higher proportions of monocytes and resting CD4 memory T cells were observed in the low- and high-risk groups, respectively. In conclusion, the BM-related gene risk score model can guide the clinical management of WHO grade II and III gliomas.

Characterizing genes associated with cancer using the CRISPR/Cas9 system: A systematic review of genes and methodological approaches

The CRISPR/Cas9 system enables a versatile set of genomes editing and genetic-based disease modeling tools due to its high specificity, efficiency, and accessible design and implementation. In cancer, the CRISPR/Cas9 system has been used to characterize genes and explore different mechanisms implicated in tumorigenesis. Different experimental strategies have been proposed in recent years, showing dependency on various intrinsic factors such as cancer type, gene function, mutation type, and technical approaches such as cell line, Cas9 expression, and transfection options. However, the successful methodological approaches, genes, and other experimental factors have not been analyzed. We, therefore, initially considered more than 1,300 research articles related to CRISPR/Cas9 in cancer to finally examine more than 400 full-text research publications. We summarize findings regarding target genes, RNA guide designs, cloning, Cas9 delivery systems, cell enrichment, and experimental validations. This analysis provides valuable information and guidance for future cancer gene validation experiments.

DNA Damage Response Evaluation Provides Novel Insights for Personalized Immunotherapy in Glioma

Background

DNA damage response (DDR) proficiency is the principal mechanism of temozolomide (TMZ) resistance in glioma. Accumulating evidence has also suggested the determining role of DDR in anticancer immunity. We propose that a comprehensive investigation of the DDR landscape can optimize glioma treatment.

Methods

We identified the pronounced enrichment of DDR in TMZ-resistant glioma cells by RNA sequencing. Nine differentially expressed genes between TMZ-sensitive/resistant glioma cells were selected to construct the DDR score through lasso regression analysis. Two glioma cohorts from TCGA and CGGA were interrogated to evaluate the predictive ability of DDR score. Multiple algorithms were applied to estimate the immunotherapeutic responses of two DDR phenotypes. Immunohistochemistry was used to determine the protein levels of PD-L1 and TGFβ in glioma specimens. The oncoPredict package was employed to predict the candidate chemotherapy agents.

Results

DDR score exhibited a robust prognostic capability in TCGA and CGGA cohorts and served as an independent predictive biomarker in glioma patients. Functional enrichment analyses revealed that high and low DDR score groups were characterized by distinct immune activity and metabolic processes. Elevated levels of infiltrating immune cells (including CD8+ T cells, CD4+ T cells, and dendritic cells) were observed in the high DDR score glioma. Further, high DDR scores correlated with increased mutation burden, up-regulated immune checkpoints, and tumor immunity activation, indicating a profound interplay between DDR score and glioma immunogenicity. In addition, PD-L1 and TGFβ were overexpressed in recurrent glioma specimens compared with primary ones. Finally, we estimated that PI3K inhibitors may serve as latent regimens for high DDR score patients.

Conclusion

Our study highlighted the promising prognostic role of DDR score in glioma. Individual assessment of DDR status for patients with glioma may provide new clues for developing immunotherapeutic strategies.

CRISPR/Cas9 gene editing: a new approach for overcoming drug resistance in cancer

The CRISPR/Cas9 system is an RNA-based adaptive immune system in bacteria and archaea. Various studies have shown that it is possible to target a wide range of human genes and treat some human diseases, including cancers, by the CRISPR/Cas9 system. In fact, CRISPR/Cas9 gene editing is one of the most efficient genome manipulation techniques. Studies have shown that CRISPR/Cas9 technology, in addition to having the potential to be used as a new therapeutic approach in the treatment of cancers, can also be used to enhance the effectiveness of existing treatments. Undoubtedly, the issue of drug resistance is one of the main obstacles in the treatment of cancers. Cancer cells resist anticancer drugs by a variety of mechanisms, such as enhancing anticancer drugs efflux, enhancing DNA repair, enhancing stemness, and attenuating apoptosis. Mutations in some proteins of different cellular signaling pathways are associated with these events and drug resistance. Recent studies have shown that the CRISPR/Cas9 technique can be used to target important genes involved in these mechanisms, thereby increasing the effectiveness of anticancer drugs. In this review article, studies related to the applications of this technique in overcoming drug resistance in cancer cells will be reviewed. In addition, we will give a brief overview of the limitations of the CRISP/Cas9 gene-editing technique.

ATRX loss promotes immunosuppressive mechanisms in IDH1 mutant glioma

BACKGROUND

ATRX inactivation occurs with IDH1R132H and p53 mutations in over 80% of Grades II/III astrocytomas. It is believed that ATRX loss contributes to oncogenesis by dysregulating epigenetic and telomere mechanisms but effects on anti-glioma immunity have not been explored. This paper examines how ATRX loss contributes to the malignant and immunosuppressive phenotypes of IDH1R132H/p53mut glioma cells and xenografts.

METHODS

Isogenic astrocytoma cells (+/-IDH1R132H/+/-ATRXloss) were established in p53mut astrocytoma cell lines using lentivirus encoding doxycycline-inducible IDH1R132H, ATRX shRNA, or Lenti-CRISPR/Cas9 ATRX. Effects of IDH1R132H+/-ATRXloss on cell migration, growth, DNA repair, and tumorigenicity were evaluated by clonal growth, transwell and scratch assays, MTT, immunofluorence and immunoblotting assays, and xenograft growth. Effects on the expression and function of modulators of the immune microenvironment were quantified by qRT-PCR, immunoblot, T-cell function, macrophage polarization, and flow cytometry assays. Pharmacologic inhibitors were used to examine epigenetic drivers of the immunosuppressive transcriptome of IDH1R132H/p53mut/ATRXloss cells.

RESULTS

Adding ATRX loss to the IDH1R132H/p53mut background promoted astrocytoma cell aggressiveness, induced expression of BET proteins BRD3/4 and an immune-suppressive transcriptome consisting of up-regulated immune checkpoints (e.g., PD-L1, PD-L2) and altered cytokine/chemokine profiles (e.g., IL33, CXCL8, CSF2, IL6, CXCL9). ATRX loss enhanced the capacity of IDH1R132H/p53mut cells to induce T-cell apoptosis, tumorigenic/anti-inflammatory macrophage polarization and Treg infiltration. The transcriptional and biological immune-suppressive responses to ATRX loss were enhanced by temozolomide and radiation and abrogated by pharmacologic BET inhibition.

CONCLUSIONS

ATRX loss activates a BRD-dependent immune-suppressive transcriptome and immune escape mechanism in IDH1R132H/p53mut astrocytoma cells.

ATRX-Deficient High-Grade Glioma Cells Exhibit Increased Sensitivity to RTK and PDGFR Inhibitors

High-grade glioma, including anaplastic astrocytoma and glioblastoma (GBM) patients, have a poor prognosis due to the lack of effective treatments. Therefore, the development of new therapeutic strategies to treat these gliomas is urgently required. Given that high-grade gliomas frequently harbor mutations in the SNF2 family chromatin remodeler ATRX, we performed a screen to identify FDA-approved drugs that are toxic to ATRX-deficient cells. Our findings reveal that multi-targeted receptor tyrosine kinase (RTK) and platelet-derived growth factor receptor (PDGFR) inhibitors cause higher cellular toxicity in high-grade glioma ATRX-deficient cells. Furthermore, we demonstrate that a combinatorial treatment of RTKi with temozolomide (TMZ)-the current standard of care treatment for GBM patients-causes pronounced toxicity in ATRX-deficient high-grade glioma cells. Our findings suggest that combinatorial treatments with TMZ and RTKi may increase the therapeutic window of opportunity in patients who suffer high-grade gliomas with ATRX mutations. Thus, we recommend incorporating the ATRX status into the analyses of clinical trials with RTKi and PDGFRi.

Construction of Novel Methylation-Driven Gene Model and Investigation of PARVB Function in Glioblastoma

Background

Glioblastoma multiforme (GBM) is characterized by widespread genetic and transcriptional heterogeneity. Aberrant DNA methylation plays a vital role in GBM progression by regulating gene expression. However, little is known about the role of methylation and its association with prognosis in GBM. Our aim was to explore DNA methylation-driven genes (DMDGs) and provide evidence for survival prediction and individualized treatment of GBM patients.

Methods

Use of the MethylMix R package identified DMDGs in GBM. The prognostic signature of DMDGs based on the risk score was constructed by multivariate Cox regression analysis. Receiver operating characteristics (ROC) curve and C-index were applied to assess the predictive performance of the DMDG prognostic signature. The predictive ability of the multigene signature model was validated in TCGA and CGGA cohorts. Finally, the role of DMDG β-Parvin (PARVB) was explored in vitro.

Results

The prognostic signature of DMDGs was constructed based on six genes (MDK, NMNAT3, PDPN, PARVB, SERPINB1, and UPP1). The low-risk cohort had significantly better survival than the high-risk cohort (p < 0.001). The area under the curve of the ROC of the six-gene signature was 0.832, 0.927, and 0.980 within 1, 2, and 3 years, respectively. The C-index of 0.704 indicated superior specificity and sensitivity. The six-gene model has been demonstrated to be an independent prognostic factor for GBM. In addition, joint survival analysis indicated that the MDK, NMNAT3, PARVB, SERPINB1, and UPP1 genes were significantly associated with prognosis and therapeutic targets for GBM. Importantly, our DMDG prognostic model was more suitable and accurate for low-grade gliomas. Finally, we verified that PARVB induced epithelial-mesenchymal transition partially through the JAK2/STAT3 pathway, which in turn promoted GBM cell proliferation, migration, and invasion.

Conclusion

This study demonstrated the potential value of the prognostic signature of DMDGs and provided important bioinformatic and potential therapeutic target data to facilitate individualized treatment for GBM, and to elucidate the specific mechanism by which PARVB promotes GBM progression.

Applications of CRISPR-Cas9 Technology to Genome Editing in Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is an aggressive malignancy of the brain and spinal cord with a poor life expectancy. The low survivability of GBM patients can be attributed, in part, to its heterogeneity and the presence of multiple genetic alterations causing rapid tumor growth and resistance to conventional therapy. The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR associated (Cas) nuclease 9 (CRISPR-Cas9) system is a cost-effective and reliable gene editing technology, which is widely used in cancer research. It leads to novel discoveries of various oncogenes that regulate autophagy, angiogenesis, and invasion and play important role in pathogenesis of various malignancies, including GBM. In this review article, we first describe the principle and methods of delivery of CRISPR-Cas9 genome editing. Second, we summarize the current knowledge and major applications of CRISPR-Cas9 to identifying and modifying the genetic regulators of the hallmark of GBM. Lastly, we elucidate the major limitations of current CRISPR-Cas9 technology in the GBM field and the future perspectives. CRISPR-Cas9 genome editing aids in identifying novel coding and non-coding transcriptional regulators of the hallmarks of GBM particularly in vitro, while work using in vivo systems requires further investigation.

Roles of Long Noncoding RNAs in Conferring Glioma Progression and Treatment

Accompanying the development of biomedicine, our knowledge of glioma, one of the most common primary intracranial carcinomas, is becoming more comprehensive. Unfortunately, patients with glioblastoma (GBM) still have a dismal prognosis and a high relapse rate, even with standard combination therapy, namely, surgical resection, postoperative radiotherapy and chemotherapy. The absence of validated biomarkers is responsible for the majority of these poor outcomes, and reliable therapeutic targets are indispensable for improving the prognosis of patients suffering from gliomas. Identification of both precise diagnostic and accurate prognostic markers and promising therapeutic targets has therefore attracted considerable attention from researchers. Encouragingly, accumulating evidence has demonstrated that long noncoding RNAs (lncRNAs) play important roles in the pathogenesis and oncogenesis of various categories of human tumors, including gliomas. Nevertheless, the underlying mechanisms by which lncRNAs regulate diverse biological behaviors of glioma cells, such as proliferation, invasion and migration, remain poorly understood. Consequently, this review builds on previous studies to further summarize the progress in the field of lncRNA regulation of gliomas over recent years and addresses the potential of lncRNAs as diagnostic and prognostic markers and therapeutic targets.

ALT Positivity in Human Cancers: Prevalence and Clinical Insights

Many exciting advances in cancer-related telomere biology have been made in the past decade. Of these recent advances, great progress has also been made with respect to the Alternative Lengthening of Telomeres (ALT) pathway. Along with a better understanding of the molecular mechanism of this unique telomere maintenance pathway, many studies have also evaluated ALT activity in various cancer subtypes. We first briefly review and assess a variety of commonly used ALT biomarkers. Then, we provide both an update on ALT-positive (ALT+) tumor prevalence as well as a systematic clinical assessment of the presently studied ALT+ malignancies. Additionally, we discuss the pathogenetic alterations in ALT+ cancers, for example, the mutation status of ATRX and DAXX, and their correlations with the activation of the ALT pathway. Finally, we highlight important ALT+ clinical associations within each cancer subtype and subdivisions within, as well as their prognoses. We hope this alternative perspective will allow scientists, clinicians, and drug developers to have greater insight into the ALT cancers so that together, we may develop more efficacious treatments and improved management strategies to meet the urgent needs of cancer patients.

The association of sex-biased ATRX mutation in female gastric cancer patients with enhanced immunotherapy-related anticancer immunity

BACKGROUND

Genetic alterations have been proven to be the promising biomarkers for ICI response. However, sex biases in genetic alterations have been often ignored in the field of immunotherapy, which might specially influence the anticancer immunity and immunotherapy efficacy in male or female patients. Here, we have systematically evaluated the effect of the sex biases in somatic mutation of gastric cancer (GC) patients on the anticancer immunity and clinical benefit to immunotherapy.

METHODS

Genomic and transcriptomic data of gastric cancer were downloaded from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC). We also obtained the genomic and clinical data of a MSKCC ICI-treated cohort from cbioportal database. GC male and female-derived tumor somatic mutation profiles were compared by maftools R package. Single sample gene set enrichment analysis (ssGSEA) was conducted to calculate the score of the anticancer immunity indicators including IFN-γ signaling, cytolytic activity (CYT) and antigen presenting machinery (APM).

RESULTS

ATRX was found to mutate more frequently in female GC patients compared to male patients (FDR = 0.0108). Female GC patients with ATRX mutation manifested significantly more MSI-high subtypes, increased TMB and PDL1 expression as well as higher scores of IFN-γ signaling, CYT and APM. Gene set enrichment analysis (GSEA) has shown that ATRX mutation might enhance the immunogenicity and anticancer immunity through affecting DNA damage repair pathways. In the ICI-treated cohort from MSKCC, GC patients with ATRX mutation were associated with prolonged overall survival. When stratifying the entire ICI-treated cohort by sex, female patients with ATRX mutation obtained significantly better survival benefits than that of ATRX mutant male patients (Female patients, HR of ATRX MT vs WT = 0.636, 95%CI = 0.455-0.890, P = 0.023; Male patients, HR of ATRX MT vs WT = 0.929, 95%CI = 0.596-1.362, P = 0.712).

CONCLUSIONS

ATRX mutation might serve as a potential predictive biomarker for favorable clinical benefit to ICI in female GC patients. ATRX mutation could be applied in combination with other biomarkers of ICI response to better identify the female GC patients who will derive greater benefits from ICI therapy.

Chromatin Manipulation and Editing: Challenges, New Technologies and Their Use in Plants

An ongoing challenge in functional epigenomics is to develop tools for precise manipulation of epigenetic marks. These tools would allow moving from correlation-based to causal-based findings, a necessary step to reach conclusions on mechanistic principles. In this review, we describe and discuss the advantages and limits of tools and technologies developed to impact epigenetic marks, and which could be employed to study their direct effect on nuclear and chromatin structure, on transcription, and their further genuine role in plant cell fate and development. On one hand, epigenome-wide approaches include drug inhibitors for chromatin modifiers or readers, nanobodies against histone marks or lines expressing modified histones or mutant chromatin effectors. On the other hand, locus-specific approaches consist in targeting precise regions on the chromatin, with engineered proteins able to modify epigenetic marks. Early systems use effectors in fusion with protein domains that recognize a specific DNA sequence (Zinc Finger or TALEs), while the more recent dCas9 approach operates through RNA-DNA interaction, thereby providing more flexibility and modularity for tool designs. Current developments of "second generation", chimeric dCas9 systems, aiming at better targeting efficiency and modifier capacity have recently been tested in plants and provided promising results. Finally, recent proof-of-concept studies forecast even finer tools, such as inducible/switchable systems, that will allow temporal analyses of the molecular events that follow a change in a specific chromatin mark.

Valproic Acid Enhanced Apoptosis by Promoting Autophagy Via Akt/mTOR Signaling in Glioma

Glioma is the most common malignant tumor in the central nervous system with a poor median survival. Valproic acid (VPA), a widely used antiepileptic drug, has been found to have antitumor effects on gliomas, but its role still has not been determined. In this study, we investigated VPA-induced apoptotic and autophagic effects on human U251 and SNB19 cells by cell counting kit-8 assay, flow cytometry, terminal deoxynucleotidyl transferase-mediated nick end labeling staining, western blots, and immunofluorescence assay in vitro, and then we further explored the role of autophagy in apoptosis by using the selective antagonist MHY1485. The data showed that VPA inhibited U251 and SNB19 glioma cells viability in a dose-dependent and time-dependent manner and induced apoptosis through the mitochondria-dependent pathway in vitro. In addition, VPA activated the Akt/mTOR pathway by decreasing their protein phosphorylation to promote cellular apoptosis. Surprisingly, the mTOR agonist MHY1485, causing a strong elevation of mTOR activity, partially reduced apoptosis ratio, which supposing that the autophagy of VPA is involved in the regulation of apoptosis. These findings suggest that VPA enhanced apoptosis by promoting autophagy via Akt/mTOR signaling in glioma, which could be further evaluated as a reliable therapy for glioma.

Involvement of N-methylpurine DNA glycosylase in resistance to temozolomide in patient-derived glioma cells

Chemotherapy for high-grade astrocytic tumors is mainly based on the use of temozolomide (TMZ), whose efficacy is limited by resistance mechanisms. Despite many investigations pointing to O6-methylguanine-DNA-methyltransferase (MGMT) as being responsible for tumor chemo-resistance, its expression does not predict an accurate response in most gliomas, suggesting that MGMT is not the only determinant of response to treatment. In this sense, several reports indicate that N-methylpurine-DNA-glycosylase (MPG) may be involved in that resistance. With that in mind, we evaluated for the first time the degree of resistance to TMZ treatment in 18 patient-derived glioma cells and its association with MGMT and MPG mRNA levels. Viability cell assays showed that TMZ treatment hardly caused growth inhibition in the patient-derived cells, even in high concentrations, indicating that all primary cultures were chemo-resistant. mRNA expression analyses showed that the TMZ-resistant phenotype displayed by cells is associated with an elevated expression of MPG to a greater extent than it is with transcript levels of MGMT. Our findings suggest that not only is MGMT implicated in resistance to TMZ but MPG, the first enzyme in base excision repair processing, is also involved, supporting its potential role as a target in anti-resistance chemotherapy for astrocytoma and glioblastoma.

CAMTA1, a novel antitumor gene, regulates proliferation and the cell cycle in glioma by inhibiting AKT phosphorylation

Identifying biomarkers for the early diagnosis of glioma and elucidating the molecular mechanisms underlying the development of this cancer are of considerable clinical importance. Recently, studies performing microarray profiling of genes to identify distinct gene signatures reported specific subtypes with predictive and prognostic relevance. Thus, we performed deep sequencing on a total of 26 glioma tissue samples to identify the frequently mutated of oncogenes and tumor suppressors in gliomas. A total of 2306 single-nucleotide polymorphisms (SNPs) and 2010 insertion and deletion sites (indels) were found by aligning sequencing information from 26 glioma samples with sequences from the normal human gene database (GRCh37/hg19). GSEA results suggest that an underexpressed gene, calmodulin binding transcription activator 1 (CAMTA1), participates in the cell proliferation and cell cycle regulation of glioma cells. Moreover, overexpression of CAMTA1 in glioma cells notably inhibited cell growth, migration, invasion and cell cycle and enhanced temozolomide (TMZ)-induced cell apoptosis in glioma cells, while CAMTA1 overexpression decreased the ITGA5, ITGB1, p-AKT, p-FAK, and Myc protein levels, suggesting that the signaling pathways of these proteins might be involved in the cellular functions of CAMTA1 in glioma. Moreover, overexpression of CAMTA1 attenuated the growth and tumorigenesis of glioma in vivo. In summary, we identified high-frequency mutant genes in glioma and provided an experimental basis for a novel mechanism by which CAMTA1 may serve as a tumor suppressor in glioma.

Mutant IDH1 Enhances Temozolomide Sensitivity via Regulation of the ATM/CHK2 Pathway in Glioma

PURPOSE

Isocitrate dehydrogenase 1 (IDH1) mutations are the most common genetic abnormalities in low-grade gliomas and secondary glioblastomas. Glioma patients with these mutations had better clinical outcomes. However, the effect of IDH1 mutation on drug sensitivity is still under debate.

Materials and Methods

IDH1-R132H mutant cells were established by lentivirus. IDH1-R132H protein expression was confirmed by western blot. The expression of ataxia telangiectasia mutated (ATM) signaling pathway and apoptosis-related proteins were detected by immunofluorescence and western blot. Temozolomide (TMZ) induced cell apoptosis was detected by flow cytometry. Tumor cell proliferation was detected by Cell Counting Kit-8. In vivo nude mice were used to confirm the in vitro roles of IDH1 mutation.

RESULTS

We established glioma cell lines that expressed IDH1-R132H mutation stably. We found that TMZ inhibited glioma cells proliferation more significantly in IDH1 mutant cells compared to wild type. The IC50 of TMZ in IDH1-R132H mutant group was less than half that of wild-type group (p < 0.01). TMZ significantly induced more DNA damage (quantification of γH2AX expression in IDH1 mutation vs. wild type, p < 0.05) and apoptosis (quantification of AnnexinV+propidium iodide-cells in IDH1 mutation versus wild type, p < 0.01) in IDH1 mutant gliomas compared to wild-type gliomas. The ATM-associated DNA repair signal was impaired in IDH1 mutant cells. Inhibiting the ATM/checkpoint kinase 2DNA repair pathway further sensitized IDH1 mutant glioma cells to chemotherapy. We found that IDH1 mutation significantly inhibited tumor growth in vivo (the tumor size was analyzed statistically, p < 0.05). Moreover, we confirmed that gliomas with IDH1 mutation were more sensitive to TMZ in vivo compared to wild type significantly and the results were consistent with the in vitro experiment.

CONCLUSION

These results provide evidence that combination of TMZ and ATM inhibitor enhances the antitumor effect in IDH1 mutant gliomas.

Tumor Cell-Derived TGFβ1 Attenuates Antitumor Immune Activity of T Cells via Regulation of PD-1 mRNA

Dysfunction in T-cell antitumor activity contributes to the tumorigenesis, progression, and poor outcome of clear cell renal cell carcinoma (ccRCC), with this dysfunction resulting from high expression of programmed cell death-1 (PD-1) in T cells. However, the molecular mechanisms maintaining high PD-1 expression in T cells have not been fully investigated in ccRCC. Here, we describe a mechanism underlying the regulation of PD-1 at the mRNA level and demonstrated its impact on T-cell dysfunction. Transcriptomic analysis identified a correlation between TGFβ1 and PD-1 mRNA levels in ccRCC samples. The mechanism underlying the regulation of PD-1 mRNA was then investigated in vitro and in vivo using syngeneic tumor models. We also observed that TGFβ1 had prognostic significance in patients with ccRCC, and its expression was associated with PD-1 mRNA expression. CcRCC-derived TGFβ1 activated P38 and induced the phosphorylation of Ser¹⁰ on H3, which recruited p65 to increase SRSF3 and SRSF5 expression in T cells. As a result, the half-life of PD-1 mRNA in T cells was prolonged. SRSF3 coordinated with NXF1 to induce PD-1 mRNA extranuclear transport in T cells. We then demonstrated that TGFβ1 could induce SRSF3 expression to restrict the antitumor activity of T cells, which influenced immunotherapy outcomes in ccRCC mouse models. Our findings highlight that tumor-derived TGFβ1 mediates immune evasion and has potential as a prognostic biomarker and therapeutic target in ccRCC.See related Spotlight on p. 1464.

CRISPR/Cas9 for overcoming drug resistance in solid tumors

OBJECTIVES

In this review, we focus on the application of clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated nuclease 9 (Cas9), as a powerful genome editing system, in the identification of resistance mechanisms and in overcoming drug resistance in the most frequent solid tumors.

DATA ACQUISITION

Data were collected by conducting systematic searching of scientific English literature using specific keywords such as "cancer", "CRISPR" and related combinations.

RESULTS

The review findings revealed the importance of CRISPR/Cas9 system in understanding drug resistance mechanisms and identification of resistance-related genes such as PBRM1, SLFN11 and ATPE1 in different cancers. We also provided an overview of genes, including RSF1, CDK5, and SGOL1, whose disruption can synergize with the currently available drugs such as paclitaxel and sorafenib.

CONCLUSION

The data suggest CRISPR/Cas9 system as a useful tool in elucidating the molecular basis of drug resistance and improving clinical outcomes. Graphical abstract The mechanisms of CRISPR/Cas9-mediated genome editing and double-strand breaks (DSBs) repair.

Targeting of endoplasmic reticulum (ER) stress in gliomas

Gliomas remain a group of malignant brain tumors with dismal prognosis and limited treatment options with molecular mechanisms being constantly investigated. The past decade, extracellular stress and intracellular DNA damage have been shown to disturb proteostasis leading to Endoplasmic Reticulum (ER) stress that is implicated in the regulation of gene expression and the pathogenesis of several tumor types, including gliomas. Upon ER stress induction, neoplastic cells activate the adaptive mechanism of unfolded protein response (UPR), an integrated signaling system that either restores ER homeostasis or induces cell apoptosis. Recently, the manipulation of the UPR has emerged as a new therapeutic target in glioma treatment. General UPR activators or selective GRP78, ATF6 and PERK inducers have been detected to modulate cell proliferation and induce apoptosis of glioma cells. At the same time, target-specific UPR inhibitors and small molecule proteostasis disruptors, work in reverse to increase misfolded proteins and cause a dysregulation in protein maturation and sorting, thus preventing the growth of neoplastic cells. Herein, we discuss the pathogenic implication of ER stress in gliomas onset and progression, providing an update on the current UPR modifying agents that can be potentially used in glioma treatment.

CRISPR/Cas9 for cancer treatment: technology, clinical applications and challenges

Clustered regularly interspaced short palindromic repeats (CRISPR) is described as RNA mediated adaptive immune system defense, which is naturally found in bacteria and archaea. CRISPR-Cas9 has shown great promise for cancer treatment in cancer immunotherapy, manipulation of cancer genome and epigenome and elimination or inactivation of carcinogenic viral infections. However, many challenges remain to be addressed to increase its efficacy, including off-target effects, editing efficiency, fitness of edited cells, immune response and delivery methods. Here, we explain CRISPR-Cas classification and its general function mechanism for gene editing. Then, we summarize these preclinical CRISPR-Cas9-based therapeutic strategies against cancer. Moreover, the challenges and improvements of CRISPR-Cas9 clinical applications will be discussed.

ATRX/EZH2 complex epigenetically regulates FADD/PARP1 axis, contributing to TMZ resistance in glioma

Rationale: Glioma is the most common primary malignant brain tumor in adults. Chemoresistance of temozolomide (TMZ), the first-line chemotherapeutic agent, is a major issue in the management of patients with glioma. Alterations of alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene constitute one of the most prevalent genetic abnormalities in gliomas. Therefore, elucidation of the role of ATRX contributing to TMZ resistance in glioma is urgently needed.

Methods: We performed the bioinformatics analysis of gene expression, and DNA methylation profiling, as well as RNA and ChIP-seq data sets. CRISPR-Cas9 gene editing system was used to achieve the ATRX knockout in TMZ resistant cells. In vitro and in vivo experiments were carried out to investigate the role of ATRX contributing to TMZ resistance in glioma.

Results: We found that ATRX expression was upregulated via DNA demethylation mediated by STAT5b/TET2 complex and strengthened DNA damage repair by stabilizing PARP1 protein in TMZ resistant cells. ATRX elicited PARP1 stabilization by the down-regulating of FADD expression via the H3K27me3 enrichment, which was dependent on ATRX/EZH2 complex in TMZ resistant cells. Magnetic resonance imaging (MRI) revealed that the PARP inhibitor together with TMZ inhibited glioma growth in ATRX wild type TMZ resistant intracranial xenograft models.

Conclusions: The present study further illustrated the novel mechanism of the ATRX/PARP1 axis contributing to TMZ resistance. Our results provided substantial new evidence that PARP inhibitor might be a potential adjuvant agent in overcoming ATRX mediated TMZ resistance in glioma.

IFI30 Is a Novel Immune-Related Target with Predicting Value of Prognosis and Treatment Response in Glioblastoma

Purpose

As a crucial part of anti-tumor immunotherapy, interferon-α/β (IFN-α/β) treatment has been broadly applied to clinical trials of glioma. However, less is known about implement of interferon-γ (IFN-γ) in glioma. Further investigating the valuable hub molecular of IFN-γ family might provide us a novel guidance for glioma therapy.

Methods

This study carried out an analysis on glioma patients from the Chinese Glioma Genome Atlas (CGGA) and The Cancer Genome Atlas (TCGA) cohorts. The analyses were performed by GraphPad Prism 8 and R language. All the validated experiments were performed three times independently.

Results

We identified IFI30 as the most stable independent prognostic gene among 20 classical IFN-γ stimulated genes (ISGs) in glioma patients. Furthermore, we found that IFI30 highly expressed in malignant subtypes of glioma and associated with chemotherapy response. We also found IFI30 could activate IL6-STAT6 signal pathway to decline the glioma cells' chemotherapy sensitivity by performing experiments. Gene ontology (GO) analysis showed IFI30 associated with enhanced leucocyte mediated immune and inflammatory response. Microenvironment analysis referred that high IFI30 expression accompanied with more infiltration of M2 type macrophages.

Conclusion

IFI30 is involved in the malignant progression and chemotherapy response of glioblastoma, which can be a potential target for treatment in glioblastoma patients.

Dual functionalized brain-targeting nanoinhibitors restrain temozolomide-resistant glioma via attenuating EGFR and MET signaling pathways

Activation of receptor tyrosine kinase (RTK) protein is frequently observed in malignant progression of gliomas. In this study, the crosstalk activation of epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) signaling pathways is demonstrated to contribute to temozolomide (TMZ) resistance, resulting in an unfavorable prognosis for patients with glioblastoma. To simultaneously mitigate EGFR and MET activation, a dual functionalized brain-targeting nanoinhibitor, BIP-MPC-NP, is developed by conjugating Inherbin3 and cMBP on the surface of NHS-PEG₈-Mal modified MPC-nanoparticles. In the presence of BIP-MPC-NP, DNA damage repair is attenuated and TMZ sensitivity is enhanced via the down-regulation of E2F1 mediated by TTP in TMZ resistant glioma. In vivo magnetic resonance imaging (MRI) shows a significant repression in tumor growth and a prolonged survival of mice after injection of the BIP-MPC-NP and TMZ. These results demonstrate the promise of this nanoinhibitor as a feasible strategy overcoming TMZ resistance in glioma.

QKI deficiency maintains glioma stem cell stemness by activating the SHH/GLI1 signaling pathway

PURPOSE

Glioblastoma (GBM) stem cells (GSCs) have been found to be the main cause of malignant GBM progression. It has also been found that Quaking homolog (QKI) plays a predominant role in driving GBM development. Here, we aimed to asses the role of QKI in maintaining GSC stemness and inducing the invasiveness of GBM cells.

METHODS

Public databases were used to assess the expression of QKI and its correlation with stemness markers in primary GBMs. The CRISPR-Cas9 technology was used to generate QKI knockout GBM cells, and RNA immunoprecipitation was used to assess QKI-GLI1 protein-mRNA interactions. In addition, in vitro and in vivo GBM cell proliferation, migration, xenografting and neurosphere formation assays were performed.

RESULTS

Using public GBM databases, QKI was identified as a potential GSC regulator. We found that QKI could inhibit stem-like cell (SLC) stemness and prolong the survival of xenografted mice. Mechanistically, we found that QKI knockout increased the GLI Family Zinc Finger 1 (GLI1) mRNA level, which is essential for maintaining the self-renewal ability of GSCs. In addition, we found that QKI knockout activated the Hedgehog signaling pathway via Tra-2 and GLI response element (TGE)-specific GLI1 mRNA disruption.

CONCLUSION

Our data indicate that upregulation of GLI1 induced by QKI deficiency maintains GSC stemness and enhances the invasiveness of GBM cells, thereby hinting at new options for the treatment of GBM.

Risk of Adverse Vascular Events in Patients with Malignant Glioma Treated with Bevacizumab Plus Irinotecan: A Systematic Review and Meta-Analysis

BACKGROUND

Bevacizumab plus irinotecan is a new beneficial chemotherapy strategy for patients with malignant glioma. The purpose of this systematic review and meta-analysis was to comprehensively assess the risk of adverse vascular events in adults with malignant glioma treated with bevacizumab plus irinotecan.

METHODS

The Cochrane Library, Embase and PubMed were searched, and relevant trials were identified up to June 2018. Two investigators screened all titles and abstracts for possible inclusion and extracted data independently. Six studies were included, and 5 of them in the control group using bevacizumab alone or bevacizumab with temozolomide. Three systems were used to assess the quality of evidence and the level of recommendation. The Oxford Centre for Evidence-Based Medicine Levels of Evidence (2009) system was used to classify the evidence into 5 levels (classes I-V). The star system from the Newcastle-Ottawa Scale was used to assess methodological quality. The GRADE profiler was used to evaluate the overall body of evidence.

RESULTS

Our data show that bevacizumab plus irinotecan therapy does not significantly affect the risk of systemic adverse events (odds ratio [OR], 1.17; 95% confidence interval [CI], 0.43-3.18). Patients treated with bevacizumab plus irinotecan had a similar risk of hematotoxicity (OR, 1.06; 95% CI, 0.26-4.38), thrombocytopenia (OR, 1.07; 95% CI, 0.25-4.63), and hypertension (OR, 1.34; 95% CI, 0.28-6.36) compared with the control group (those treated without irinotecan). Thrombosis occurred more frequently in patients treated with bevacizumab plus irinotecan compared with the control group (OR, 3.23; 95% CI, 1.47-7.12).

CONCLUSIONS

The risk of systemic adverse events was not significantly different between patients with malignant glioma treated with bevacizumab plus irinotecan and the control group. The risks of hematotoxicity, thrombocytopenia, and hypertension were similar in the 2 groups. The risk of thrombosis was higher in patients treated with bevacizumab plus irinotecan. Monitoring for thrombosis and administering anticoagulant therapy as necessary merit promotion for patients with malignant glioma receiving treatment with bevacizumab plus irinotecan.

DNA repair in personalized brain cancer therapy with temozolomide and nitrosoureas

Alkylating agents have been used since the 60ties in brain cancer chemotherapy. Their target is the DNA and, although the DNA of normal and cancer cells is damaged unselectively, they exert tumor-specific killing effects because of downregulation of some DNA repair activities in cancer cells. Agents exhibiting methylating properties (temozolomide, procarbazine, dacarbazine, streptozotocine) induce at least 12 different DNA lesions. These are repaired by damage reversal mechanisms involving the alkyltransferase MGMT and the alkB homologous protein ALKBH2, and through base excision repair (BER). There is a strong correlation between the MGMT expression level and therapeutic response in high-grade malignant glioma, supporting the notion that O⁶-methylguanine and, for nitrosoureas, O⁶-chloroethylguanine are the most relevant toxic damages at therapeutically relevant doses. Since MGMT has a significant impact on the outcome of anti-cancer therapy, it is a predictive marker of the effectiveness of methylating anticancer drugs, and clinical trials are underway aimed at assessing the influence of MGMT inhibition on the therapeutic success. Other DNA repair factors involved in methylating drug resistance are mismatch repair, DNA double-strand break (DSB) repair by homologous recombination (HR) and DSB signaling. Base excision repair and ALKBH2 might also contribute to alkylating drug resistance and their downregulation may have an impact on drug sensitivity notably in cells expressing a high amount of MGMT and at high doses of temozolomide, but the importance in a therapeutic setting remains to be shown. MGMT is frequently downregulated in cancer cells (up to 40% in glioblastomas), which is due to CpG promoter methylation. Astrocytoma (grade III) are frequently mutated in isocitrate dehydrogenase (IDH1). These tumors show a surprisingly good therapeutic response. IDH1 mutation has an impact on ALKBH2 activity thus influencing DNA repair. A master switch between survival and death is p53, which often retains transactivation activity (wildtype) in malignant glioma. The role of p53 in regulating survival via DNA repair and the routes of death are discussed and conclusions as to cancer therapeutic options were drawn.

DNA damage repair alterations modulate M2 polarization of microglia to remodel the tumor microenvironment via the p53-mediated MDK expression in glioma

Background

DNA damage repair (DDR) alterations are important events in cancer initiation, progression, and therapeutic resistance. However, the involvement of DDR alterations in glioma malignancy needs further investigation. This study aims to characterize the clinical and molecular features of gliomas with DDR alterations and elucidate the biological process of DDR alterations that regulate the cross talk between gliomas and the tumor microenvironment.

Methods

Integrated transcriptomic and genomic analyses were undertaken to conduct a comprehensive investigation of the role of DDR alterations in glioma. The prognostic DDR-related cytokines were identified from multiple datasets. In vivo and in vitro experiments validated the role of p53, the key molecule of DDR, regulating M2 polarization of microglia in glioma.

Findings

DDR alterations are associated with clinical and molecular characteristics of glioma. Gliomas with DDR alterations exhibit distinct immune phenotypes, and immune cell types and cytokine processes. DDR-related cytokines have an unfavorable prognostic implication for GBM patients and are synergistic with DDR alterations. Overexpression of MDK mediated by p53, the key transcriptional factor in DDR pathways, remodels the GBM immunosuppressive microenvironment by promoting M2 polarization of microglia, suggesting a potential role of DDR in regulating the glioma microenvironment.

Interpretation

Our work suggests that DDR alterations significantly contribute to remodeling the glioma microenvironment via regulating the immune response and cytokine pathways.

Fund

This study was supported by: 1. The National Key Research and Development Plan (No. 2016YFC0902500); 2. National Natural Science Foundation of China (No. 81702972, No. 81874204, No. 81572701, No. 81772666); 3. China Postdoctoral Science Foundation (2018M640305); 4. Special Fund Project of Translational Medicine in the Chinese-Russian Medical Research Center (No. CR201812); 5. The Research Project of the Chinese Society of Neuro-oncology, CACA (CSNO-2016-MSD12); 6. The Research Project of the Health and Family Planning Commission of Heilongjiang Province (2017–201); and 7. Harbin Medical University Innovation Fund (2017LCZX37, 2017RWZX03).

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Gliomas with DNA damage repair alterations had distinct genomic variation spectrum.

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DDR alterations exhibit distinct immune phenotypes, cytokine processes and immune cell types in glioma.

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DDR-related cytokines in GME have an unfavorable prognostic implication for GBM patients.

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P53-mediated midkine expression derived from glioma cells promotes M2 polarization of microglia.

Loss of GINS2 inhibits cell proliferation and tumorigenesis in human gliomas

AIMS

In this study, we examined the expression of GINS2 in glioma and determined its role in glioma development.

METHODS

The protein expression of GINS2 was assessed in 120 human glioma samples via immunohistochemistry. Then, we suppressed the expression of GINS2 in glioma cell strains U87 and U251 using a short hairpin RNA lentiviral vector. In addition, RNA sequencing and bioinformatics analysis were performed on glioma cells before and after GINS2 knockdown. Subsequent co-immunoprecipitation and western blot experiments indicated possible downstream regulatory molecules.

RESULTS

The present results showed that GINS2 can accelerate the growth of glioma cells, whereas the suppression of GINS2 expression decreased the proliferation and tumorigenicity of glioma cells. Mechanism research experiments proved that GINS2 can block the cell cycle by regulating certain downstream molecules, such as MCM2, ATM, and CHEK2.

CONCLUSION

GINS2 is closely related to the occurrence and development of glioma, and is likely to become a prognostic marker for glioma patients, as well as a potential therapeutic target in the treatment of glioma.

Potential Strategies Overcoming the Temozolomide Resistance for Glioblastoma

Glioblastoma (GBM) is a highly malignant type of primary brain tumor with a high mortality rate. Although the current standard therapy consists of surgery followed by radiation and temozolomide (TMZ), chemotherapy can extend patient's post-operative survival but most cases eventually demonstrate resistance to TMZ. O6-methylguanine-DNA methyltransferase (MGMT) repairs the main cytotoxic lesion, as O6-methylguanine, generated by TMZ, can be the main mechanism of the drug resistance. In addition, mismatch repair and BER also contribute to TMZ resistance. TMZ treatment can induce self-protective autophagy, a mechanism by which tumor cells resist TMZ treatment. Emerging evidence also demonstrated that a small population of cells expressing stem cell markers, also identified as GBM stem cells (GSCs), contributes to drug resistance and tumor recurrence owing to their ability for self-renewal and invasion into neighboring tissue. Some molecules maintain stem cell properties. Other molecules or signaling pathways regulate stemness and influence MGMT activity, making these GCSs attractive therapeutic targets. Treatments targeting these molecules and pathways result in suppression of GSCs stemness and, in highly resistant cases, a decrease in MGMT activity. Recently, some novel therapeutic strategies, targeted molecules, immunotherapies, and microRNAs have provided new potential treatments for highly resistant GBM cases. In this review, we summarize the current knowledge of different resistance mechanisms, novel strategies for enhancing the effect of TMZ, and emerging therapeutic approaches to eliminate GSCs, all with the aim to produce a successful GBM treatment and discuss future directions for basic and clinical research to achieve this end.