Autophagy-induced KDR/VEGFR-2 activation promotes the formation of vasculogenic mimicry by glioma stem cells

Dual role of exosomal circCMTM3 derived from GSCs in impeding degradation and promoting phosphorylation of STAT5A to facilitate vasculogenic mimicry formation in glioblastoma

Background: Glioblastoma (GBM) is characterized by abundant neovascularization as an essential hallmark. Vasculogenic mimicry (VM) is a predominant pattern of GBM neovascularization. However, the biological functions of circRNAs prompting VM formation in GBM remains unclarified. Methods: The circular RNA circCMTM3 was identified through high-throughput sequencing and bioinformatics analysis. The expression of circCMTM3 in exosomes in glioma tissues and cells was verified via RT-qPCR and FISH. In vitro and in vivo assays, such as EdU, MTS, Transwell, and tube formation assays were performed to investigate functional roles of circCMTM3. Meanwhile, in situ tumorigenesis assay were implemented to explore the influences of circCMTM3 on the GBM progression. Additionally, RNA pull-down, RIP, ChIP, and dual-luciferase reporter gene assays were executed to confirm the underlying regulation mechanism of circCMTM3. Results: CircCMTM3, as a novel circular RNA, was packaged into exosomes derived from glioblastoma stem cells (GSCs), which facilitates the phenotypic transition of differentiated glioma cells (DGCs) to VM. Mechanistically, exosomal circCMTM3 is internalized by DGCs and disrupt the ubiquitination degradation of STAT5A and STAT5B by E3 ubiquitin ligase CNOT4. Additionally, through molecular scaffold function of circCMTM3, STAT5A is activated and triggers transcriptional regulation of target genes including the pro-vasculogenic factor CHI3L2 and the RNA-binding protein SRSF1. Subsequently, circCMTM3/STAT5A/SRSF1 positive feedback loop sustainably enhances VM formation and accelerates tumor progression in GBM. Conclusion: Exosomal circCMTM3 possessing growth factor-mimetic property activates the JAK2/STAT5A pathway via non-canonical manner, and promotes VM formation in GBM. The molecular communications between GSCs and DGCs offers a therapeutic strategy for targeting the neovascularization of GBM.

Cancer plasticity in therapy resistance: Mechanisms and novel strategies

Therapy resistance poses a significant obstacle to effective cancer treatment. Recent insights into cell plasticity as a new paradigm for understanding resistance to treatment: as cancer progresses, cancer cells experience phenotypic and molecular alterations, corporately known as cell plasticity. These alterations are caused by microenvironment factors, stochastic genetic and epigenetic changes, and/or selective pressure engendered by treatment, resulting in tumor heterogeneity and therapy resistance. Increasing evidence suggests that cancer cells display remarkable intrinsic plasticity and reversibly adapt to dynamic microenvironment conditions. Dynamic interactions between cell states and with the surrounding microenvironment form a flexible tumor ecosystem, which is able to quickly adapt to external pressure, especially treatment. Here, this review delineates the formation of cancer cell plasticity (CCP) as well as its manipulation of cancer escape from treatment. Furthermore, the intrinsic and extrinsic mechanisms driving CCP that promote the development of therapy resistance is summarized. Novel treatment strategies, e.g., inhibiting or reversing CCP is also proposed. Moreover, the review discusses the multiple lines of ongoing clinical trials globally aimed at ameliorating therapy resistance. Such advances provide directions for the development of new treatment modalities and combination therapies against CCP in the context of therapy resistance.

Dual perspective on autophagy in glioma: Detangling the dichotomous mechanisms of signaling pathways for therapeutic insights

Autophagy is a normal physiological process that aids the recycling of cellular nutrients, assisting the cells to cope with stressed conditions. However, autophagy's effect on cancer, including glioma, is uncertain and involves complicated molecular mechanisms. Several contradictory reports indicate that autophagy may promote or suppress glioma growth and progression. Autophagy inhibitors potentiate the efficacy of chemotherapy or radiation therapy in glioma. Numerous compounds stimulate autophagy to cause glioma cell death. Autophagy is also involved in the therapeutic resistance of glioma. This review article aims to detangle the complicated molecular mechanism of autophagy to provide a better perception of the two-sided role of autophagy in glioma and its therapeutic implications. The protein and epigenetic modulators of the cytoprotective and cytotoxic role of autophagy are described in this article. Moreover, several signaling pathways are associated with autophagy and its effects on glioma. We have reviewed the molecular pathways and highlighted the signaling axis involved in cytoprotective and cytotoxic autophagy. Additionally, this article discusses the role of autophagy in therapeutic resistance, including glioma stem cell maintenance and tumor microenvironment regulation. It also summarizes several investigations on the anti-glioma effects of autophagy modulators to understand the associated mechanisms and provide insights regarding its therapeutic implications.

PDCL3 as a prognostic factor and associated with the VEGF signaling pathway in glioma

BACKGROUND

New targeted drugs about angiogenesis could develop the treatment of glioma. We aimed to explore the role of phosducin like 3 (PDCL3) in angiogenesis of glioma.

MATERIALS AND METHODS

RNA sequencing data and matched clinical data were downloaded from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. To screen for the reliable genes with the filtering analyses, survival, multivariate Cox, receiver operating characteristic (ROC) curve filtration, and clinical correlation analyses were performed. The PDCL3 gene was validated by immunohistochemistry as a reliable gene for further analysis. Then we used the combined data of TCGA and Genotype-Tissue Expression from UCSC to detect the differential gene expression of PDCL3. Related signal pathways in glioma were explored by the gene set enrichment analysis and co-expression analysis. Lastly, we performed in vitro experiments to verify the gene functions and related mechanisms.

RESULTS

The three filtering analyses and immunostaining indicated that the expression of PDCL3 in glioma tissues was higher than the normal tissues. Gene function analysis showed that PDCL3 activated the vascular endothelial growth factor (VEGF) signal pathway, and its mechanism was related to pathways in cancer, like NOD like receptor signaling pathway, the RIG-I like receptor signaling pathway and the P53 signaling pathway by MAPK/AKT in gliomas. This suggested that the proliferation, migration and invasion of glioma cells might be inhibited by the downregulation of PDCL3 in vitro, which may be related to the activation of VEGF signaling pathway.

CONCLUSION

We demonstrated that PDCL3 could function as an independent adverse prognostic marker in glioma. Its pro-oncogenic mechanism may be related to the VEGF signaling pathway.

Cancer stem cell mimicry for immune evasion and therapeutic resistance

Cancer stem cells (CSCs) are heterogeneous, possess self-renewal attributes, and orchestrate important crosstalk in tumors. We propose that the CSC state represents "mimicry" by cancer cells that leads to phenotypic plasticity. CSC mimicry is suggested as CSCs can impersonate immune cells, vasculo-endothelia, or lymphangiogenic cells to support cancer growth. CSCs facilitate both paracrine and juxtracrine signaling to prime tumor-associated immune and stromal cells to adopt pro-tumoral phenotypes, driving therapeutic resistance. Here, we outline the ingenuity of CSCs' mimicry in their quest to evade immune detection, which leads to immunotherapeutic resistance, and highlight CSC-mimicry-targeted therapeutic strategies for robust immunotherapy.

A gene delivery system with autophagy blockade for enhanced anti-angiogenic therapy against Fusobacterium nucleatum-associated colorectal cancer

Anti-angiogenesis has emerged a promising strategy against colorectal cancer (CRC). However, the efficacy of anti-angiogenic therapy is greatly compromised by the up-regulated autophagy levels resulting from the evolutionary resistance mechanism and the presence of Fusobacterium nucleatum (F. nucleatum) in CRC. Herein, we report a cationic polymer capable of blocking autophagic flux to deliver plasmid DNA (pDNA) encoding soluble FMS-like tyrosine kinase-1 (sFlt-1) for enhanced anti-angiogenic therapy against F. nucleatum-associated CRC. The autophagy-inhibiting cationic polymer, referred to as PNHCQ, is synthesized by conjugating hydroxychloroquine (HCQ) into 3,3'-diaminodipropylamine-pendant poly(β-benzyl-L-aspartate) (PAsp(Nors)), which can be assembled and electrostatically interacted with sFlt-1 plasmid to form PNHCQ/sFlt-1 polyplexes. Hydrophobic HCQ modification not only boosts transfection efficiency but confers autophagy inhibition activity to the polymer. Hyaluronic acid (HA) coating is further introduced to afford PNHCQ/sFlt-1@HA for improved tumor targeting without compromising on transfection. Consequently, PNHCQ/sFlt-1@HA demonstrates significant anti-tumor efficacy in F. nucleatum-colocalized HT29 mouse xenograft model by simultaneously exerting anti-angiogenic effects through sFlt-1 expression and down-regulating autophagy levels exacerbated by F. nucleatum challenge. The combination of anti-angiogenic gene delivery and overall autophagy blockade effectively sensitizes CRC tumors to anti-angiogenesis, providing an innovative approach for enhanced anti-angiogenic therapy against F. nucleatum-resident CRC. STATEMENT OF SIGNIFICANCE: Up-regulated autophagy level within tumors is considered responsible for the impaired efficacy of clinic antiangiogenic therapy against CRC colonized with pathogenic F. nucleatum. To tackle this problem, an autophagy-inhibiting cationic polymer is developed to enable efficient intracellular delivery of plasmid DNA encoding soluble FMS-like tyrosine kinase-1 (sFlt-1) and enhance anti-angiogenic therapy against F. nucleatum-associated CRC. HA coating that can be degraded by tumor-enriching hyaluronidase is further introduced for improved tumor targeting without compromising transfection efficiency. The well-orchestrated polyplexes achieve considerable tumor accumulation, efficient in vivo transfection, and effectively reinforce the sensitivity of CRC to the sFlt-1-derived anti-angiogenic effects by significantly blocking overall autophagy flux exacerbated by F. nucleatum challenge, thus harvesting robust antitumor outcomes against F. nucleatum-resident CRC.

HNRNPA2B1 stabilizes NFATC3 levels to potentiate its combined actions with FOSL1 to mediate vasculogenic mimicry in GBM cells

BACKGROUND

Vasculogenic mimicry (VM) is an enigmatic physiological feature that influences blood supply within glioblastoma (GBM) tumors for their sustained growth. Previous studies identify NFATC3, FOSL1 and HNRNPA2B1 as significant mediators of VEGFR2, a key player in vasculogenesis, and their molecular relationships may be crucial for VM in GBM.

AIMS

The aim of this study was to understand how NFATC3, FOSL1 and HNRNPA2B1 collectively influence VM in GBM.

METHODS

We have investigated the underlying gene regulatory mechanisms for VM in GBM cell lines U251 and U373 in vitro and in vivo. In vitro cell-based assays were performed to explore the role of NFATC3, FOSL1 and HNRNPA2B1 in GBM cell proliferation, VM and migration, in the context of RNA interference (RNAi)-mediated knockdown alongside corresponding controls. Western blotting and qRT-PCR assays were used to examine VEGFR2 expression levels. CO-IP was employed to detect protein-protein interactions, ChIP was used to detect DNA-protein complexes, and RIP was used to detect RNA-protein complexes. Histochemical staining was used to detect VM tube formation in vivo.

RESULTS

Focusing on NFATC3, FOSL1 and HNRNPA2B1, we found each was significantly upregulated in GBM and positively correlated with VM-like cellular behaviors in U251 and U373 cell lines. Knockdown of NFATC3, FOSL1 or HNRNPA2B1 each resulted in decreased levels of VEGFR2, a key growth factor gene that drives VM, as well as the inhibition of proliferation, cell migration and extracorporeal VM activity. Chromatin immunoprecipitation (ChIP) studies and luciferase reporter gene assays revealed that NFATC3 binds to the promoter region of VEGFR2 to enhance VEGFR2 gene expression. Notably, FOSL1 interacts with NFATC3 as a co-factor to potentiate the DNA-binding capacity of NFATC3, resulting in enhanced VM-like cellular behaviors. Also, level of NFATC3 protein in cells was enhanced through HNRNPA2B1 binding of NFATC3 mRNA. Furthermore, RNAi-mediated silencing of NFATC3, FOSL1 and HNRNPA2B1 in GBM cells reduced their capacity for tumor formation and VM-like behaviors in vivo.

CONCLUSION

Taken together, our findings identify NFATC3 as an important mediator of GBM tumor growth through its molecular and epistatic interactions with HNRNPA2B1 and FOSL1 to influence VEGFR2 expression and VM-like cellular behaviors.

Cyclopeptide moroidin inhibits vasculogenic mimicry formed by glioblastoma cells via regulating β-catenin activation and EMT pathways

Glioblastoma (GBM) is a highly vascularized malignant brain tumor with poor clinical outcomes. Vasculogenic mimicry (VM) formed by aggressive GBM cells is an alternative approach for tumor blood supply and contributes to the failure of anti-angiogenic therapy. To date, there is still a lack of effective drugs that target VM formation in GBM. In the present study, we evaluated the effects of the plant cyclopeptide moroidin on VM formed by GBM cells and investigated its underlying molecular mechanisms. Moroidin significantly suppressed cell migration, tube formation, and the expression levels of α-smooth muscle actin and matrix metalloproteinase-9 in human GBM cell lines at sublethal concentrations. The RNA sequencing data suggested the involvement of the epithelial-mesenchymal transition (EMT) pathway in the mechanism of moroidin. Exposure to moroidin led to a concentration-dependent decrease in the expression levels of the EMT markers N-cadherin and vimentin in GBM cells. Moreover, moroidin significantly reduced the level of phosphorylated extracellular signal-regulated protein kinase (p-ERK) and inhibited the activation of β-catenin. Finally, we demonstrated that the plant cyclopeptide moroidin inhibited VM formation by GBM cells through inhibiting the ERK/β-catenin-mediated EMT. Therefore, our study indicates a potential application of moroidin as an anti-VM agent in the treatment of GBM.

The addition of chloroquine and bevacizumab to standard radiochemotherapy for recurrent glioblastoma multiforme

INTRODUCTION

Hypoxia-induced autophagy leads to an increase in vasculogenic-mimicry (VM) and the development of resistance of glioblastoma-cells to bevacizumab (BEV). Chloroquine (HCQ) inhibits autophagy, reduces VM and can thus produce a synergistic effect in anti-angiogenic-therapy by delaying the development of resistance to BEV.

PURPOSE

We retrospectively compared the combined addition of HCQ+BEV and adjuvant-radiochemotherapy (aRCT) to aRCT alone for recurrent-glioblastoma (rGBM) in regards of overall survival (OS).

METHODS

Between 2006 and 2016, 134 patients underwent neurosurgery for rGBM at our institution. Forty-two patients (Karnofsky-Performance-Score>60%) with primary-glioblastoma underwent repeat-surgery and aRCT for recurrence. Four patients (9.5%) received aRCT+HCQ+BEV. Five patients received aRCT+BEV.

RESULTS

In rGBM-patients who were treated with aRCT+HCQ+BEV, median OS was 36.57 months and median post-recurrence-survival (PRS) was 23.92 months while median PRS in the control-group was 9.63 months (p=0.022). In patients who received aRCT+BEV, OS and PRS were 26.83 and 12.97 months, respectively.

CONCLUSIONS

Although this study was performed on a small number of highly selected patients, it demonstrates a synergistic effect of HCQ+BEV in the treatment of rGBM which previously could be demonstrated based on experimental data. A significant increase of OS in patients who receive aRCT+HCQ+BEV cannot be ruled out and should be further investigated in randomised-controlled-trials.

The E3 ubiquitin ligase RNF135 modulates chemotherapy resistance to oxaliplatin for colorectal cancer by modulating autophagy

BACKGROUND

RING finger protein 135 plays an important role in tumorigenesis and is associated with drug resistance.

METHODS

Bioinformatics analysis showed that RNF135 was significantly differentially expressed in colorectal cancer. RT-qPCR and western blot were used to detect the expression of RNF135. Immunohistochemical analysis were used to measure the expression of RNF135 and Ki-67.

RESULTS

The expression of RNF135 was up-regulated in human tissue samples and colorectal cancer and was positively correlated with Ki-67. Compared with oxaliplatin sensitive patients, RNF135 expression levels were higher in the tissue of resistant patients. The regulatory effect of RNF135 on colorectal cancer cells was further investigated in vitro. Therefore, inhibition of autophagy by down-regulating RNF135 can partially increase its susceptibility to oxaliplatin.

HMGA2 promotes nasopharyngeal carcinoma progression and is associated with tumor resistance and poor prognosis

Nasopharyngeal carcinoma (NPC), as one of the most prevalent malignancies in the head and neck region, still lacks a complete understanding of its pathogenesis. Presently, radiotherapy, concurrent chemoradiotherapy, and targeted therapy stand as the primary modalities for treating NPC. With advancements in medicine, the cure rates for nasopharyngeal carcinoma have been steadily increasing. Nevertheless, recurrence and metastasis persist as the primary reasons for treatment failure. Consequently, a profound exploration of the molecular mechanisms underlying the occurrence and progression of nasopharyngeal carcinoma, along with the exploration of corresponding therapeutic approaches, becomes particularly imperative in the quest for comprehensive solutions to combat this disease. High mobility group AT-hook 2 (HMGA2) is a pivotal protein capable of altering chromatin structure, regulating gene expression, and influencing transcriptional activity. In the realm of cancer research, HMGA2 exhibits widespread dysregulation, playing a crucial role in nearly all malignant tumors. It is implicated in various tumorigenic processes, including cell cycle regulation, cell proliferation, epithelial-mesenchymal transition, angiogenesis, tumor invasion, metastasis, and drug resistance. Additionally, HMGA2 serves as a molecular marker and an independent prognostic factor in certain malignancies. Recent studies have increasingly unveiled the critical role of HMGA2 in nasopharyngeal carcinoma (NPC), particularly in promoting malignant progression, correlating with tumor resistance, and serving as an independent adverse prognostic factor. This review focuses on elucidating the oncogenic role of HMGA2 in NPC, suggesting its potential association with chemotherapy resistance in NPC, and proposing its candidacy as an independent factor in nasopharyngeal carcinoma prognosis assessment.

Autophagy Behavior in Endothelial Cell Regeneration

Autophagy plays a crucial role in maintaining endothelial cell homeostasis through the turnover of intracellular components during stress conditions in a lysosomal-dependent manner. The regeneration strategy involves several aspects, including autophagy. Autophagy is a catabolic degenerative lysosomal-dependent degradation of intracellular components. Autophagy modifies cellular and subcellular endothelial cell functions, including mitochondria stress, lysosomal stress, and endoplasmic reticulum unfolded protein response. Activation of common signaling pathways of autophagy and regeneration and enhancement of intracellular endothelial cell metabolism serve as the bases for the induction of endothelial regeneration. Endothelial progenitor cells include induced pluripotent stem cells (iPSC), embryonic stem cells, and somatic cells, such as fibroblasts. Future strategies of endothelial cell regeneration involve the induction of autophagy to minimize the metabolic degeneration of the endothelial cells and optimize the regeneration outcomes.

Tumor-derived lactate promotes resistance to bevacizumab treatment by facilitating autophagy enhancer protein RUBCNL expression through histone H3 lysine 18 lactylation (H3K18la) in colorectal cancer

Bevacizumab plays an important role in the first and second line treatment for metastatic colorectal cancer (CRC). And induction of hypoxia and the tumors response to it plays an important role in determining the efficacy of antiangiogenic therapy while the connection between them remains unclear. Here, we found that lactate accumulated in the tumor environment of CRC and acted as substrates for histone lactylation, and this process was further induced by cellular enhanced glycolysis in hypoxia. We determined that CRC patients resistant to bevacizumab treatment presented with elevated levels of histone lactylation and inhibition of histone lactylation efficiently suppressed CRC tumorigenesis, progression and survival in hypoxia. Histone lactylation promoted the transcription of RUBCNL/Pacer, facilitating autophagosome maturation through interacting with BECN1 (beclin 1) and mediating the recruitment and function of the class III phosphatidylinositol 3-kinase complex, which had a crucial role in hypoxic cancer cells proliferation and survival. Moreover, combining inhibition of histone lactylation and macroautophagy/autophagy with bevacizumab treatment demonstrated remarkable treatment efficacy in bevacizumab-resistance patients-derived pre-clinical models. These findings delivered a new exploration and important supplement of metabolic reprogramming-epigenetic regulation, and provided a new strategy for improving clinical efficacy of bevacizumab in CRC by inhibition of histone lactylation.Abbreviations: 2-DG: 2-deoxy-D-glucose; BECN1: beclin 1; CQ: chloroquine; CRC: colorectal cancer; DMOG: dimethyloxalylglycine; H3K18la: histone H3 lysine 18 lactylation; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; Nala: sodium lactate; PDO: patient-derived orgnoid; PDX: patient-derived xenograft; RUBCNL/Pacer: rubicon like autophagy enhancer; SQSTM1/p62: sequestosome 1.

Cellular stress responses as modulators of drug cytotoxicity in pharmacotherapy of glioblastoma

Despite the extensive efforts to find effective therapeutic strategies, glioblastoma (GBM) remains a therapeutic challenge with dismal prognosis of survival. Over the last decade the role of stress responses in GBM therapy has gained a great deal of attention, since depending on the duration and intensity of these cellular programs they can be cytoprotective or promote cancer cell death. As such, initiation of the UPR, autophagy or oxidative stress may either impede or facilitate drug-mediated cell killing. In this review, we summarize the mechanisms that regulate ER stress, autophagy, and oxidative stress during GBM development and progression to later discuss the involvement of these stress pathways in the response to different treatments. We also discuss how a precise understanding of the molecular mechanisms regulating stress responses evoked by different pharmacological agents could decisively contribute to the design of novel and more effective combinational treatments against brain malignancies.

EIF4A3 induced circGRIK2 promotes the malignancy of glioma by regulating the miR-1303/HOXA10 axis

In recent years, the role of circular RNAs (circRNAs) in glioma has become increasingly important. However, there are still many newly discovered circRNAs with unknown functions that require further study. In this study, circRNA sequencing, qPCR, MTS, EdU, Transwell, and other assays were conducted to detect the expression and malignant effects of a novel circRNA molecule, circGRIK2, in glioma. qPCR, western blotting, RIP, and luciferase reporter gene experiments were used to investigate the downstream molecular mechanisms of circGRIK2. Our study found that circGRIK2 was highly expressed in glioma and promoted glioma cell viability, proliferation, invasion, and migration. Mechanistically, circGRIK2 acted as a competitive sponge for miR-1303, upregulating the expression of HOXA10 to exert its oncogenic effects. Additionally, the RNA-binding protein EIF4A3 could bind to and stabilize circGRIK2, leading to its high expression in glioblastoma. The discovery of circGRIK2 in this study not only contributes to a better understanding of the biological mechanisms of circGRIK2 in glioma but also provides a new target for molecular targeted therapy.

Pseudogene MAPK6P4-encoded functional peptide promotes glioblastoma vasculogenic mimicry development

Glioma is the most common primary malignancy of the central nervous system. Glioblastoma (GBM) has the highest degree of malignancy among the gliomas and the strongest resistance to chemotherapy and radiotherapy. Vasculogenic mimicry (VM) provides tumor cells with a blood supply independent of endothelial cells and greatly restricts the therapeutic effect of anti-angiogenic tumor therapy for glioma patients. Vascular endothelial growth factor receptor 2 (VEGFR2) and vascular endothelial cadherin (VE-cadherin) are currently recognized molecular markers of VM in tumors. In the present study, we show that pseudogene MAPK6P4 deficiency represses VEGFR2 and VE-cadherin protein expression levels, as well as inhibits the proliferation, migration, invasion, and VM development of GBM cells. The MAPK6P4-encoded functional peptide P4-135aa phosphorylates KLF15 at the S238 site, promoting KLF15 protein stability and nuclear entry to promote GBM VM formation. KLF15 was further confirmed as a transcriptional activator of LDHA, where LDHA binds and promotes VEGFR2 and VE-cadherin lactylation, thereby increasing their protein expression. Finally, we used orthotopic and subcutaneous xenografted nude mouse models of GBM to verify the inhibitory effect of the above factors on GBM VM development. In summary, this study may represent new targets for the comprehensive treatment of glioma.

The driving mechanism and targeting value of mimicry between vascular endothelial cells and tumor cells in tumor progression

The difficulty and poor prognosis of malignant tumor have always been a difficult problem to be solved. The internal components of solid tumor are complex, including tumor cells, stromal cells and immune cells, which play an important role in tumor proliferation, migration, metastasis and drug resistance. Hence, targeting of only the tumor cells will not likely improve survival. Various studies have reported that tumor cells and endothelial cells have high plasticity, which is reflected in the fact that they can simulate each other's characteristics by endothelial-mesenchymal transition (EndMT) and vasculogenic mimicry (VM). In this paper, this mutual mimicry concept was integrated and reviewed for the first time, and their similarities and implications for tumor development are discussed. At the same time, possible therapeutic methods are proposed to provide new directions and ideas for clinical targeted therapy and immunotherapy of tumor.

Sulforaphane protects microvascular endothelial cells in lower limb ischemia/reperfusion injury mice

Background: Microvascular damage is a key pathological factor in acute lower limb ischemia/reperfusion (I/R) injury. Current evidence suggests that sulforaphane (SFN) protects tissue from I/R injury. However, the role of SFN in acute lower limb I/R injury remains elusive. This study aimed to investigate the role and potential mechanism of SFN in I/R-related microvascular damage in the limb. Methods: Limb viability was evaluated by laser Doppler imaging, tissue edema analysis and histological analysis. Western blotting and immunofluorescence were applied to analyze the levels of apoptosis, oxidative stress, autophagy, transcription factor EB (TFEB) activity and mucolipin 1 (MCOLN1)-calcineurin signaling pathway. Results: SFN administration significantly ameliorated I/R-induced hypoperfusion, tissue edema, skeletal muscle fiber injury and endothelial cell (EC) damage in the limb. Pharmacological inhibition of NFE2L2 (nuclear factor, erythroid 2 like 2) reversed the anti-oxidation and anti-apoptosis effects of SFN on ECs. Additionally, silencing of TFEB by interfering RNA abolished the SFN-induced autophagy restoration, anti-oxidant response and anti-apoptosis effects on ECs. Furthermore, silencing of MCOLN1 by interfering RNA and pharmacological inhibition of calcineurin inhibited the activity of TFEB induced by SFN, demonstrating that SFN regulates the activity of TFEB through the MCOLN1-calcineurin signaling pathway. Conclusion: SFN protects microvascular ECs against I/R injury by TFEB-mediated autophagy restoration and anti-oxidant response.

Pyroptosis, ferroptosis, and autophagy cross-talk in glioblastoma opens up new avenues for glioblastoma treatment

Glioma is a common primary tumor of the central nervous system (CNS), with glioblastoma multiforme (GBM) being the most malignant, aggressive, and drug resistant. Most drugs are designed to induce cancer cell death, either directly or indirectly, but malignant tumor cells can always evade death and continue to proliferate, resulting in a poor prognosis for patients. This reflects our limited understanding of the complex regulatory network that cancer cells utilize to avoid death. In addition to classical apoptosis, pyroptosis, ferroptosis, and autophagy are recognized as key cell death modalities that play significant roles in tumor progression. Various inducers or inhibitors have been discovered to target the related molecules in these pathways, and some of them have already been translated into clinical treatment. In this review, we summarized recent advances in the molecular mechanisms of inducing or inhibiting pyroptosis, ferroptosis, or autophagy in GBM, which are important for treatment or drug tolerance. We also discussed their links with apoptosis to better understand the mutual regulatory network among different cell death processes. Video Abstract.

Autophagic-Related Proteins in Brain Gliomas: Role, Mechanisms, and Targeting Agents

The present review focuses on the phenomenon of autophagy, a catabolic cellular process, which allows for the recycling of damaged organelles, macromolecules, and misfolded proteins. The different steps able to activate autophagy start with the formation of the autophagosome, mainly controlled by the action of several autophagy-related proteins. It is remarkable that autophagy may exert a double role as a tumour promoter and a tumour suppressor. Herein, we analyse the molecular mechanisms as well as the regulatory pathways of autophagy, mainly addressing their involvement in human astrocytic neoplasms. Moreover, the relationships between autophagy, the tumour immune microenvironment, and glioma stem cells are discussed. Finally, an excursus concerning autophagy-targeting agents is included in the present review in order to obtain additional information for the better treatment and management of therapy-resistant patients.

Single-Atom Nanocatalytic Therapy for Suppression of Neuroinflammation by Inducing Autophagy of Abnormal Mitochondria

Catalysts have achieved efficacy in scavenging reactive oxygen species (ROS) to eliminate neuroinflammation, but it ignores the essential fact of blocking the source of ROS regeneration. Here, we report the single-atom catalysts (SACs) Pt/CeO₂, which can effectively catalyze the breakdown of existing ROS and induce mitochondrial membrane potential (Δψm) depolarization by interfering with the α-glycerophosphate shuttle pathway and malate-aspartate shuttle pathway, indirectly triggering the self-clearance of dysfunctional mitochondria and thus eradicating the source of ROS generation. In a therapeutic model of Parkinson's disease (PD), Pt/CeO₂ wrapped by neutrophil-like (HL-60) cell membranes and modified by rabies virus glycoprotein (RVG29) effectively crosses the blood-brain barrier (BBB), enters dopaminergic neurons entering the neuroinflammatory region breaking down existing ROS and inducing mitophagy by electrostatic adsorption targeting mitochondria to prevent ROS regeneration after catalyst discharge. This strategy of efficiently eliminating ROS at the lesion and fundamentally blocking the source of ROS production can address both symptoms and root causes and provides a mechanism of explanation and action target for the treatment of inflammation-related diseases.

Discovery of a novel dual functional phenylpyrazole-styryl hybrid that induces apoptotic and autophagic cell death in bladder cancer cells

Unpleasant side effects and resistance development remained the Achilles heel of chemotherapy. Since low tumor-selectivity and monotonous effect of chemotherapy are closely related to such bottleneck, targeting tumor-selective multi-functional anticancer agents may be an ideal strategy in the search of new safer drugs. Herein, we report the discovery of compound 21, a nitro-substituted 1,5-diphenyl-3-styryl-1H-pyrazole that possesses dual functional characteristics. The 2D- and 3D-culture-based studies revealed that 21 not only could induce ROS-independent apoptotic and EGFR/AKT/mTOR-mediated autophagic cell deaths in EJ28 cells simultaneously but also has the ability in inducing cell death at both proliferating and quiescent zones of EJ28 spheroids. The molecular modelling analysis showed that 21 possesses EGFR targeting capability as it forms stable interactions in the EGFR active site. Together with its good safety profile in the zebrafish-based model, the present study showed that 21 is promising and may lead to the discovery of tumor-selective multi-functional anti-cancer agents.

L1CAM promotes vasculogenic mimicry formation by miR-143-3p-induced expression of hexokinase 2 in glioma

In recent decades, antiangiogenic therapy, which blocks the supply of oxygen and nutrition to tumor cells, has become a promising clinical strategy for the treatment of patients with tumors. However, recent studies revealed that vasculogenic mimicry (VM), which is the process by which vascular morphological structures are formed by highly invasive tumor cells, has been considered a potential factor for the failure of antiangiogenic therapy in patients with tumors. Thus, inhibition of VM formation might be a potential target for improving the outcome of antiangiogenic strategies. However, the mechanism underlying VM formation is still incompletely elucidated. Herein, we report that L1CAM might be a critical regulator of VM formation in glioma, and might be associated with the resistance of glioma to antiangiogenic therapy. We found that the tumor-invasion and tube-formation capabilities of L1CAM-overexpressing cells were significantly enhanced in vitro and in vivo. In addition, the results indicated that miR-143-3p, which might directly target the 3'UTR of the hexokinase 2 (HK2) gene to regulate its protein expression, was subsequently involved in L1CAM-mediated VM formation by glioma cells. Further study revealed that the regulation of MMP2, MMP9, and VEGFA expression was involved in this process. Moreover, we identified that activation of the downstream PI3K/AKT signaling pathway of the L1CAM/HK2 cascade is critical for VM formation by glioma cells. Furthermore, we found that the combined treatment of anti-L1CAM neutralizing monoclonal antibody and bevacizumab increases efficacy beyond that of bevacizumab alone, and suppresses glioma growth in vivo, indicating that the inhibition of L1CAM-mediated VM formation might efficiently improve the effect of antiangiogenic treatment for glioma patients. Together, our findings demonstrated a critical role of L1CAM in regulating VM formation in glioma, and that L1CAM might be a potential target for ameliorating tumor resistance to antiangiogenic therapy in glioma patients.

MicroRNA-588 regulates the invasive, migratory and vasculogenic mimicry-forming abilities of hypoxic glioma cells by targeting ROBO1

BACKGROUND

The microenvironment of hypoxia is an important factor contributing to the development of glioblastoma (GBM). MicroRNA-588 and its potential target Roundabout-directed receptor 1 (ROBO1) have been reported to promote tumor invasion and proliferation in diseases such as gastric, pancreatic and hepatocellular carcinoma, while their function in GBM and response to hypoxic states remain elusive.

METHODS

A microarray was leveraged to identify differentially expressed microRNAs in U251 glioma cells cultured under normoxic and hypoxic conditions. The expression of miR-588 was assessed using quantitative real-time PCR (qRT‒PCR). Gain- and loss-of-function studies were used to evaluate the role of miR-588 under hypoxic and normoxic conditions. Cell invasion, migration, proliferation, and vasculogenic mimicry (VM) formation experiments were performed. The relationship between miR-588 and ROBO1 was confirmed using western blot and luciferase reporter assays. Intracranial xenograft tumor mouse models were used to study the function of miR-588 in vivo.

RESULTS

The expression of miR-588 was significantly upregulated in hypoxic glioma cells relative to normoxic glioma cells. miR-588 inhibited the invasive, migratory and VM-forming abilities of glioma cells in vitro and in vivo. Mechanistically, roundabout guidance receptor 1 (ROBO1) is a direct, functionally relevant target of miR-588 in glioma. ROBO1 knockdown suppressed the expression of matrix metallopeptidase 2 (MMP2) and matrix metallopeptidase 9 (MMP9), thereby inhibiting the invasive, migratory and VM-forming abilities of glioma.

CONCLUSIONS

MiR-588 regulated the behaviors of hypoxic glioma cells by targeting ROBO1. miR-588 can be used as a prognostic marker for glioma and has potential implications in glioma gene therapy.

Glioblastoma-Specific Strategies of Vascularization: Implications in Anti-Angiogenic Therapy Resistance

Angiogenesis has long been implicated as a crucial process in GBM growth and progression. GBM can adopt several strategies to build up its abundant and aberrant vasculature. Targeting GBM angiogenesis has gained more and more attention in anti-cancer therapy, and many strategies have been developed to interfere with this hallmark. However, recent findings reveal that the effects of anti-angiogenic treatments are temporally limited and that tumors become refractory to therapy and more aggressive. In this review, we summarize the GBM-associated neovascularization processes and their implication in drug resistance mechanisms underlying the transient efficacy of current anti-angiogenic therapies. Moreover, we describe potential strategies and perspectives to overcome the mechanisms adopted by GBM to develop resistance to anti-angiogenic therapy as new potential therapeutic approaches.

ATG5: A central autophagy regulator implicated in various human diseases

Autophagy, an intracellular conserved degradative process, plays a central role in the renewal/recycling of a cell to maintain the homeostasis of nutrients and energy within the cell. ATG5, a key component of autophagy, regulates the formation of the autophagosome, a hallmark of autophagy. ATG5 binds with ATG12 and ATG16L1 resulting in E3 like ligase complex, which is necessary for autophagosome expansion. Available data suggest that ATG5 is indispensable for autophagy and has an imperative role in several essential biological processes. Moreover, ATG5 has also been demonstrated to possess autophagy-independent functions that magnify its significance and therapeutic potential. ATG5 interacts with various molecules for the execution of different processes implicated during physiological and pathological conditions. Furthermore, ATG5 genetic variants are associated with various ailments. This review discusses various autophagy-dependent and autophagy-independent roles of ATG5, highlights its various deleterious genetic variants reported until now, and various studies supporting it as a potential drug target.

Peroxidase is a novel potential marker in glioblastoma through bioinformatics method and experimental validation

Peroxidase (PXDN), a specific extracellular matrix (ECM)-associated protein, has been determined as a tumor indicator and therapeutic target in various tumors. However, the effects of PXDN in prognostic performance and clinical implications in glioblastoma multiforme (GBM) remains unknown. Here, we assessed PXDN expression pattern and its performance on prognosis among GBM cases from TCGA and CGGA databases. PXDN was up-regulated within GBM samples in comparison with normal control. High PXDN expression was a dismal prognostic indicator in GBM. Single cell RNA analysis was conducted to detect the cell localization of PXDN. We also set up a PPI network to explore the interacting protein associated with PXDN, including TSKU, COL4A1 and COL5A1. Consistently, functional enrichment analysis revealed that several cancer hallmarks were enriched in the GBM cases with high PXDN expression, such as epithelial-mesenchymal transition (EMT), fatty acid metabolism, glycolysis, hypoxia, inflammatory response, and Wnt/beta-catenin signaling pathway. Next, this study analyzed the association of PXDN expression and immunocyte infiltration. PXDN expression was in direct proportion to the infiltrating degrees of NK cells resting, T cells regulatory, M0 macrophage, monocytes and eosinophils. The roles of PXDN on immunity were further estimated by PXDN-associated immunomodulators. In addition, four prognosis-related lncRNAs co-expressed with PXDN were identified. Finally, we observed that PXDN depletion inhibits GBM cell proliferation and migration by in vitro experiments. Our data suggested that PXDN has the potential to be a powerful prognostic biomarker, which might offer a basis for developing therapeutic targets for GBM.

Immunotherapy checkpoints in ovarian cancer vasculogenic mimicry: Tumor immune microenvironments, and drugs

Vasculogenic mimicry (VM), a vessel-like structure independent of endothelial cells, commonly exists in solid tumors which requires blood vessels to grow. As a special source of blood supply for tumor progression to a more aggressive state, VM has been observed in a variety of human malignant tumors and is tightly associated with tumor proliferation, invasion, metastasis, and poor patient prognosis. So far, various factors, including immune cells and cytokines, were reported to regulate ovarian cancer progression by influencing VM formation. Herein, we review the mechanisms that regulate VM formation in ovarian cancer and the effect of cells, cytokines, and signaling molecules in the tumor microenvironment on VM formation, Furthermore, we summarize the current clinical application of drugs targeting VM formation.

ITGA5 and ITGB1 contribute to Sorafenib resistance by promoting vasculogenic mimicry formation in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is labeled with high mortality and tolerance to chemotherapy. Sorafenib has been the first-line treatment option in HCC patients for past decades, while the therapeutic effect was limited in almost HCC patients.

METHODS

In this study, we analyzed public omics data of HCC patients with different responses to Sorafenib treatment. To confirm the role of integrins A5 and B1 (ITGA5 and ITGB1) in Sorafenib resistance, we generated the Sorafenib-resistant (Sor-R) cell lines and cells overexpressing ITGA5 or ITGB1. Hypoxia level was measured using Hypoxy probe by flow cytometry, while vasculogenic mimicry was detected and quantified by CD31 and periodic acid schiff staining.

RESULTS

Hypoxia was upregulated in non-responsive patients, accompanied with genes involved in encoding extracellular matrix components and angiogenesis such as ITGA5 and ITGB1. Sor-R hepatoma cell lines were constructed to measure expression and role of candidate genes. ITGA5 and ITGB1 were augmented in Sor-R cells. Upregulation of ITGA5 or ITGB1 reduced the sensitivity to Sorafenib in HepG2 and Huh7 cells, aggravated the hypoxic condition and resulted in formation of vascular mimicry.

CONCLUSIONS

These findings suggested that hypoxia associated vascular mimicry account for non-response to Sorafenib treatment in HCC patients. ITGA5 and ITGB1 may serve as effective predictors of HCC patients' outcome after Sorafenib treatment, which also provides a new target for HCC patients resistant to Sorafenib.

New insights into antiangiogenic therapy resistance in cancer: Mechanisms and therapeutic aspects

Angiogenesis is a hallmark of cancer and is required for tumor growth and progression. Antiangiogenic therapy has been revolutionarily developing and was approved for the treatment of various types of cancer for nearly two decades, among which bevacizumab and sorafenib continue to be the two most frequently used antiangiogenic drugs. Although antiangiogenic therapy has brought substantial survival benefits to many cancer patients, resistance to antiangiogenic drugs frequently occurs during clinical treatment, leading to poor outcomes and treatment failure. Cumulative evidence has demonstrated that the intricate interplay among tumor cells, bone marrow-derived cells, and local stromal cells critically allows for tumor escape from antiangiogenic therapy. Currently, drug resistance has become the main challenge that hinders the therapeutic efficacies of antiangiogenic therapy. In this review, we describe and summarize the cellular and molecular mechanisms conferring tumor drug resistance to antiangiogenic therapy, which was predominantly associated with redundancy in angiogenic signaling molecules (e.g., VEGFs, GM-CSF, G-CSF, and IL17), alterations in biological processes of tumor cells (e.g., tumor invasiveness and metastasis, stemness, autophagy, metabolic reprogramming, vessel co-option, and vasculogenic mimicry), increased recruitment of bone marrow-derived cells (e.g., myeloid-derived suppressive cells, tumor-associated macrophages, and tumor-associated neutrophils), and changes in the biological functions and features of local stromal cells (e.g., pericytes, cancer-associated fibroblasts, and endothelial cells). We also review potential biomarkers to predict the response to antiangiogenic therapy in cancer patients, which mainly consist of imaging biomarkers, cellular and extracellular proteins, a certain type of bone marrow-derived cells, local stromal cell content (e.g., pericyte coverage) as well as serum or plasma biomarkers (e.g., non-coding RNAs). Finally, we highlight the recent advances in combination strategies with the aim of enhancing the response to antiangiogenic therapy in cancer patients and mouse models. This review introduces a comprehensive understanding of the mechanisms and biomarkers associated with the evasion of antiangiogenic therapy in cancer, providing an outlook for developing more effective approaches to promote the therapeutic efficacy of antiangiogenic therapy.

LINC00339: An emerging major player in cancer and metabolic diseases

Long noncoding RNAs (lncRNAs) are a series of RNA molecules without ability to code proteins. LncRNAs have emerged as significant players in almost all aspects of gene function and regulation and play crucial roles in many human diseases. Particular lncRNAs are deemed to be promising molecular biomarkers used for diagnosing diseases and determining patient prognoses and treatment efficacies. LINC00339 is a new budding lncRNA and much of evidence shows that it is abnormally expressed in multifarious diseases, including endometriosis, cardiomyocyte apoptosis, osteoporosis, digestive-system tumors, respiratory-system tumors, nervous-system tumors, and diseases involving other systems. Additionally, LINC00339 is remarkably associated with different clinical features, such as tumor size, TNM stage, and pathological grade. LINC00339 expression has been proved to upregulate in the aforementioned diseases and has been identified to promote disease occurrence and development. It is also reported that LINC00339 is associated with various cellular events, such as tumor cell proliferation, motility and invasiveness, the expression has also been proved that it is closely related to clinical symptoms in cancer patients. This review summarizes the relationships among expression levels, biological features, clinical symptoms, and regulatory mechanisms of LINC00339 in several diseases and discusses the clinical applications of LINC00339 as a cancer diagnostic, prognostic and treatment efficacy biomarker.

Inhibitory Effect of MicroRNA-376b-Overexpressing Bone Marrow Mesenchymal Stem Cells (BMSCs) on Malignant Characteristics of Glioma Cells Through Targeting Forkhead Box Protein P2 (FOXP2)

This study investigated the impact of microRNA (miR)-376b derived from BMSCs on glioma progression. BMSCs were transfected with miR-376b mimic, miR-376b inhibitor or NC and then cocultured with glioma cells followed by measuring cell behaviors by MTT assay, Transwell assay and flow cytometry, FOXP2 and miR-376b expression by Western blot and RT-qPCR. After confirming the inhibitory and mimicking activity of transfection, we found that overexpression of miR-376b in BMSCs decreased glioma cell invasion, migration and proliferation but promoted cell apoptosis within 24 h and 48 h after transfection along with reduced number of cells in S-phase. Mechanically, miR-376b targeted miR-376b and up-regulation of miR-376b caused down-regulation of FOXP2 (p < 0.05). Overexpression of miR-376b in BMSCs decelerated glioma cell cycle and inhibitedmalignant behaviors of glioma cells by targeting FOXP2 expression. These evidence unveils the potential role of FOXP2 as a biomarker for the treatment of gliomas.

Overexpression of FOXD2-AS1 enhances proliferation and impairs differentiation of glioma stem cells by activating the NOTCH pathway via TAF-1

Emerging data have highlighted the importance of long noncoding RNAs (lncRNAs) in exerting critical biological functions and roles in different forms of brain cancer, including gliomas. In this study, we sought to investigate the role of lncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) in glioma cells. First, we used sphere formation assay and flow cytometry to select U251 glioma stem cells (GSCs). Then, we quantified the expression of lncRNA FOXD2-AS1, TATA-box binding protein associated factor 1 (TAF-1) and NOTCH1 in glioma tissues and GSCs, as well as the expression of GSC stem markers, OCT4, SOX2, Nanog, Nestin and CD133 in GSCs. Colony formation assay, sphere formation assay, and flow cytometry were used to evaluate GSC stemness. Next, the correlations among lncRNA FOXD2-AS1, TAF-1 and NOTCH1 were investigated. LncRNA FOXD2-AS1, TAF-1 and NOTCH1 were found to be elevated in glioma tissues and GSCs, and silencing lncRNA FOXD2-AS1 inhibited stemness and proliferation, while promoting apoptosis and differentiation of GSCs. LncRNA FOXD2-AS1 overexpression also led to increased NOTCH1 by recruiting TAF-1 to the NOTCH1 promoter region, thereby promoting stemness and proliferation, while impairing cell apoptosis and differentiation. Mechanistically, lncRNA FOXD2-AS1 elevation promoted glioma in vivo by activating the NOTCH signalling pathway via TAF-1 upregulation. Taken together, the key findings of our investigation support the proposition that downregulation of lncRNA FOXD2-AS1 presents a viable and novel molecular candidate for improving glioma treatment.

Downregulation of Astrocyte Elevated Gene-1 Expression Combined with All-Trans Retinoic Acid Inhibits Development of Vasculogenic Mimicry and Angiogenesis in Glioma

OBJECTIVE

This study aimed to investigate the effects of downregulating astrocyte elevated gene-1 (AEG-1) expression combined with all-trans retinoic acid (ATRA) on vasculogenic mimicry (VM) formation and angiogenesis in glioma.

METHODS

U87 glioma cells were transfected with AEG-1 shRNA lentiviral vectors (U87-siAEG-1) and incubated in a medium containing 20 µmol/L ATRA. Matrigel-based tube formation assay was performed to evaluate VM formation, and the cell counting kit-8 (CCK-8) assay was used to analyze the proliferation of glioma cells in vitro. Reverse transcription-quantitative polymerase chain reaction and Western blot analysis were used to investigate the mRNA and protein expression of related genes, respectively. Glioma xenograft models were generated via subcutaneous implantation of glioma cells in nude mice. Tumor-bearing mice received an intraperitoneal injection of ATRA (10 mg/kg per day). Immunohistochemistry was used to evaluate the expression of related genes and the microvessel density (MVD) in glioma xenograft models. CD34/periodic acid-Schiff double staining was performed to detect VM channels in vivo. The volume and weight of tumors were measured, and a tumor growth curve was drawn to evaluate tumor growth.

RESULTS

A combination of ATRA intervention and downregulation of AEG-1 expression significantly inhibited the proliferation of glioma cells in vitro and glioma VM formation in vitro and in vivo. It also significantly decreased MVD and inhibited tumor growth. Further, the expression levels of matrix metalloproteinase (MMP)-2, MMP-9, vascular endothelial-cadherin (VE-cadherin), and vascular endothelial growth factor (VEGF) in glioma significantly decreased in vivo and in vivo.

CONCLUSION

Hence, a combinatorial approach might be effective in treating glioma through regulating MMP-2, MMP-9, VEGF, and VE-cadherin expression.

Impact of Regorafenib on Endothelial Transdifferentiation of Glioblastoma Stem-like Cells

Glioblastomas (GBM) are aggressive brain tumours with a poor prognosis despite heavy therapy that combines surgical resection and radio-chemotherapy. The presence of a subpopulation of GBM stem cells (GSC) contributes to tumour aggressiveness, resistance and recurrence. Moreover, GBM are characterised by abnormal, abundant vascularisation. Previous studies have shown that GSC are directly involved in new vessel formation via their transdifferentiation into tumour-derived endothelial cells (TDEC) and that irradiation (IR) potentiates the pro-angiogenic capacity of TDEC via the Tie2 signalling pathway. We therefore investigated the impact of regorafenib, a multikinase inhibitor with anti-angiogenic and anti-tumourigenic activity, on GSC and TDEC obtained from irradiated GSC (TDEC IR+) or non-irradiated GSC (TDEC). Regorafenib significantly decreases GSC neurosphere formation in vitro and inhibits tumour formation in the orthotopic xenograft model. Regorafenib also inhibits transdifferentiation by decreasing CD31 expression, CD31+ cell count, pseudotube formation in vitro and the formation of functional blood vessels in vivo of TDEC and TDEC IR+. All of these results confirm that regorafenib clearly impacts GSC tumour formation and transdifferentiation and may therefore be a promising therapeutic option in combination with chemo/radiotherapy for the treatment of highly aggressive brain tumours.

Autophagy-based unconventional secretion of HMGB1 in glioblastoma promotes chemosensitivity to temozolomide through macrophage M1-like polarization

Background

Glioblastoma (GB) is the most common and highly malignant brain tumor characterized by aggressive growth and resistance to alkylating chemotherapy. Autophagy induction is one of the hallmark effects of anti-GB therapies with temozolomide (TMZ). However, the non-classical form of autophagy, autophagy-based unconventional secretion, also called secretory autophagy and its role in regulating the sensitivity of GB to TMZ remains unclear. There is an urgent need to illuminate the mechanism and to develop novel therapeutic targets for GB.

Methods

Cancer genome databases and paired-GB patient samples with or without TMZ treatment were used to assess the relationship between HMGB1 mRNA levels and overall patient survival. The relationship between HMGB1 protein level and TMZ sensitivity was measured by immunohistochemistry, ELISA, Western blot and qRT-PCR. GB cells were engineered to express a chimeric autophagic flux reporter protein consisting of mCherry, GFP and LC3B. The role of secretory autophagy in tumor microenvironment (TME) was analyzed by intracranial implantation of GL261 cells. Coimmunoprecipitation (Co-IP) and Western blotting were performed to test the RAGE-NFκB-NLRP3 inflammasome pathway.

Results

The exocytosis of HMGB1 induced by TMZ in GB is dependent on the secretory autophagy. HMGB1 contributed to M1-like polarization of tumor associated macrophages (TAMs) and enhanced the sensitivity of GB cells to TMZ. Mechanistically, RAGE acted as a receptor for HMGB1 in TAMs and through RAGE-NFκB-NLRP3 inflammasome pathway, HMGB1 enhanced M1-like polarization of TAMs. Clinically, the elevated level of HMGB1 in sera may serve as a beneficial therapeutic-predictor for GB patients under TMZ treatment.

Conclusions

We demonstrated that enhanced secretory autophagy in GB facilitates M1-like polarization of TAMs to enhance TMZ sensitivity of GB cells. HMGB1 acts as a key regulator in the crosstalk between GB cells and tumor-suppressive M1-like TAMs in GB microenvironment and may be considered as an adjuvant for the chemotherapeutic agent TMZ.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02291-8.

Decreased RNA m6A methylation enhances the process of the epithelial mesenchymal transition and vasculogenic mimicry in glioblastoma

RNA N⁶-methyladenosine (m⁶A) modification is gradually thought to be an active participant in the considerable biological processes of glioblastoma (GB), providing us with a novel insight for exploring this disease. However, the role of RNA m⁶A modification during the epithelial mesenchymal transition (EMT) or vasculogenic mimicry (VM) progression has not been investigated in GB. Here we performed a research to validate the impact exerted by AlkB homolog 5 (ALKBH5), one of "erasers" for RNA m⁶A and methyltransferase-like 3 (METTL3) which adds m⁶A modification to the RNAs on the progression of EMT and VM in GB. In this study, we demonstrate that the m⁶A levels of RNAs were reduced in GB cells and glioma tissues. Patients with high mRNA expression of ALKBH5 acquired relatively shorter median overall survival (OS) time, while patients with relatively high expression of MEETL3 prolonged their disease free survival. ALKBH5 enhanced GB cell proliferation and influenced cell cycle in vitro. Decreased RNA m⁶A methylation enhanced the progression of the EMT and VM in glioblastoma cells. ALKBH5 strengthened glioblastoma growth and enhanced the EMT and VM process of glioblastoma in vivo. Our study uncovers that RNA m⁶A methylation suppresses the process of EMT and VM in glioblastoma, providing a new perspective to seek for a potential therapeutic target for GB.

Current Understanding of Exosomal MicroRNAs in Glioma Immune Regulation and Therapeutic Responses

Exosomes, the small extracellular vesicles, are released by multiple cell types, including tumor cells, and represent a novel avenue for intercellular communication via transferring diverse biomolecules. Recently, microRNAs (miRNAs) were demonstrated to be enclosed in exosomes and therefore was protected from degradation. Such exosomal miRNAs can be transmitted to recipient cells where they could regulate multiple cancer-associated biological processes. Accumulative evidence suggests that exosomal miRNAs serve essential roles in modifying the glioma immune microenvironment and potentially affecting the malignant behaviors and therapeutic responses. As exosomal miRNAs are detectable in almost all kinds of biofluids and correlated with clinicopathological characteristics of glioma, they might be served as promising biomarkers for gliomas. We reviewed the novel findings regarding the biological functions of exosomal miRNAs during glioma pathogenesis and immune regulation. Furthermore, we elaborated on their potential clinical applications as biomarkers in glioma diagnosis, prognosis and treatment response prediction. Finally, we summarized the accessible databases that can be employed for exosome-associated miRNAs identification and functional exploration of cancers, including glioma.

Targeting regulated cell death in tumor nanomedicines

Nanomedicines hold great potential in anticancer therapy by modulating the biodistribution of nanomaterials and initiating targeted oxidative stress damage, but they are also limited by the inherent self-protection mechanism and the evolutionary treatment resistance of cancer cells. New emerging explorations of regulated cell death (RCD), including processes related to autophagy, ferroptosis, pyroptosis, and necroptosis, substantially contribute to the augmented therapeutic efficiency of tumors by increasing the sensitivity of cancer cells to apoptosis. Herein, paradigmatic studies of RCD-mediated synergistic tumor nanotherapeutics are introduced, such as regulating autophagy-enhanced photodynamic therapy (PDT), targeting ferroptosis-sensitized sonodynamic therapy (SDT), inducing necroptosis-augmented photothermal therapy (PTT), and initiating pyroptosis-collaborative chemodynamic therapy (CDT), and the coordination mechanisms are discussed in detail. Multiangle analyses addressing the present challenges and upcoming prospects of RCD-based nanomedicines have also been highlighted and prospected for their further strengthening and the broadening of their application scope. It is believed that up-and-coming coadjutant therapeutic methodologies based on RCDs will considerably impact precision nanomedicine for cancer.

Dual VEGF/PDGF knockdown suppresses vasculogenic mimicry formation in choroidal melanoma cells via the Wnt5a/β-catenin/AKT signaling pathway

OBJECTIVE

This study aimed to explore the effects of knocking down both vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) on vasculogenic mimicry (VM) formation in choroidal melanoma (CM) cells.

METHODS

Cell counting Kit (CCK)-8, monoclonal formation, wound healing, transwell and flow cytometry assays were used to observe the cell effects in CM cell line, ocular choroidal melanoma-1 cells (OCM-1) with respect to proliferation, migration, invasion and apoptosis. Three-dimensional (3D) cultures were also used to characterize VM tube structural effects in OCM-1 cells and western blotting was used to characterize protein expression changes in VM-related markers.

RESULTS

Dual VEGF/PDGF knockdown suppressed cell proliferation, migration and invasion, but promoted cell apoptosis. It also reduced VM tube structures in OCM-1 cells. VM associated markers including, VE-cadherin, EphA2 and MT1-MMP were also down-regulated in OCM-1 cells. Similarly, Wnt5a, β-catenin and phosphorylated-AKT levels were also down-regulated. Western blotting and 3D cultures further demonstrated that combined Wnt5a silencing with dual VEGF/PDGF knockdown significantly decreased VE-cadherin and EphA2 levels and reduced VM tube structures in OCM-1 cells.

CONCLUSIONS

Dual VEGF/PDGF knockdown suppressed cell growth and metastasis in OCM-1 cells, and blocked the Wnt5a/β-catenin/AKT signaling pathway thereby inhibiting VM formation.

RAB42 Promotes Glioma Pathogenesis via the VEGF Signaling Pathway

Angiogenesis plays an important role in tumor initiation and progression of glioma. Seeking for biomarkers associated with angiogenesis is important in enhancing our understanding of glioma biologically and identifying its new drug targets. RNA-sequencing (RNA-seq) data and matched clinical data were downloaded from the CGGA database. A series of filtering analyses were performed to screen for reliable genes: survival, multivariate Cox, ROC curve filtration, and clinical correlation analyses. After immunohistochemical verification, RAB42 was identified as a reliable gene for further single gene analysis. Afterwards, we performed gene set enrichment analysis (GSEA) and co-expression analysis to establish the related molecular mechanisms and signal pathways in glioma. Finally, the gene functions and the mechanisms were investigated in vitro experiments. A total of 23270 mRNA expression and 1018 glioma samples were included in this study. After the three filtering analyses, we selected ten genes for immunohistochemical verification: KLHDC8A, IKIP, HIST1H2BK, HIST1H2BJ, GNG5, FAM114A1, TMEM71, RAB42, CCDC18, and GAS2L3. Immunostaining demonstrated that RAB42 was significantly expressed on the membrane of glioma tissues but not in normal tissues. These results were verified and validated in GEPIA datasets, and the association between RAB42 with clinical features was also evaluated. Analysis of gene functions indicated that RAB42 activated VEGF signaling pathways and the mechanism was associated with natural killer cell mediated cytotoxicity, JAK-STAT signaling pathway and apoptosis pathways by PI3K/AKT in gliomas. Experiments in vitro suggested that the proliferation and invasion of glioma cells might be inhibited after downregulating of RAB42. And the tumorigenesis promotion of RAB42 may relate to the activation of VEGF signaling pathway. Taken together, this study shows that the overexpression of RAB42 is an independent prognostic factor of adverse prognosis. Its pro-oncogenic mechanism may be associated with the activation of VEGF signaling pathways.

Establishment and validation of five autophagy-related signatures for predicting survival and immune microenvironment in glioma

BACKGROUND

Gliomas, especially Glioblastoma multiforme, are the most frequent type of primary tumors in central nervous system. Increasing researches have revealed the relationship between autophagy and tumor, while the molecular mechanism of autophagy in glioma is still rarely reported.

OBJECTIVE

Our research aims to conform the autophagy-related genes (ARGs) implicated in the development and progression of glioma and improve our understanding of autophagy in glioma.

METHODS

20 candidate ARGs were screened through the protein-protein interaction network. We also downloaded the publicly accessible glioma data for 665 individuals from TCGA and 970 individuals from CGGA with RNA sequences and clinicopathological information. Subsequently, univariate and multivariate Cox regression analysis identified 5 key ARGs among the 20 candidate genes as key prognostic genes for survival, GSEA and immune response analysis.

RESULTS

ATG5, BCL2L1, CASP3, CASP8, GAPDH were identified as key ARGs in our research. Further studies showed that the high-risk population was linked to a dismal prognosis and suggested an immune-inhibitory microenvironment. GSEA results demonstrated that high risk population was closely related to DNA repair, hypoxia pathways, implicated in immunosuppression and carcinogenesis. Through CMap, we finally identified 14 candidate drugs for the ARG high risk population.

CONCLUSIONS

This study established and verified an ARG risk model, which can serve as an independent predictor for prognosis, reflect on the strength of the immune response and predict the potential drugs in glioma. Our findings offer new understandings of ARG molecular mechanism and promising therapeutic targets for glioma treatment.

Astragaloside IV enhances the sensibility of lung adenocarcinoma cells to bevacizumab by inhibiting autophagy

Bevacizumab (BV) has an inhibitory effect on tumor growth including lung adenocarcinoma. However, its efficacy is greatly affected by drug resistance. Astragaloside IV (AST-IV) is effective in combination with other drugs is effective to treat cancer. This study aimed to investigate the effect of AST-IV on enhancing the sensibility of lung adenocarcinoma cells to BV. A549 cells were treated by different concentrations of BV and AST-IV. Cell viability, cell cycle, and apoptosis were detected by thiazolyl blue tetrazolium bromide (MTT) and flow cytometry, respectively. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting were performed to detect the expression levels of autophagy- and apoptosis-related proteins, protein kinase B (AKT), and mammalian target of rapamycin (mTOR). The results showed that BV or AST-IV could inhibit the viability and promote the apoptosis of A549 cells in a concentration-dependent manner. Moreover, BV or AST-IV inhibited Bcl-2 expression and increased the expressions of Bax and Cleaved caspase-3, and promoted apoptosis. BV and AST-IV in combination acted synergistically on viability and apoptosis of A549 cells. However, BV alone down-regulated P62 expression, LC3I/LC3II level, the number of cells arrested at S phase and the phosphorylation levels of AKT and mTOR, but upregulated the number of cells arrested at G0/G1 phase and Beclin1 expression, whereas AST-IV alone could reverse the effect of BV on autophagy-related proteins, the phosphorylation levels of AKT and mTOR. This paper demonstrates that AST-IV enhances the effect of BV on inhibiting proliferation and promoting apoptosis of lung adenocarcinoma cells through inhibiting autophagy pathway.

Vasculogenic Mimicry Formation Predicts Tumor Progression in Oligodendroglioma

Vasculogenic mimicry (VM) has been identified as an important vasculogenic mechanism in malignant tumors, but little is known about its clinical meanings and mechanisms in oligodendroglioma. In this study, VM-positive cases were detected in 28 (20.6%) out of 136 oligodendroglioma samples, significantly associated with higher WHO grade, lower Karnofsky performance status (KPS) scores, and recurrent tumor (p < 0.001, p = 0.040, and p = 0.020 respectively). Patients with VM-positive oligodendroglioma had a shorter progress-free survival (PFS) compared with those with VM-negative tumor (p < 0.001), whereas no significant difference was detected in overall survival (OS) between these patients. High levels of phosphorylate serine/threonine kinases Ataxia-telangiectasia mutated (pATM) and phosphorylate Ataxia-telangiectasia and Rad3-Related (pATR) were detected in 31 (22.8%) and 34 (25.0%), respectively out of 136 oligodendroglioma samples. Higher expressions of pATM and pATR were both associated with a shorter PFS (p < 0.001 and p < 0.001). VM-positive oligodendroglioma specimens tended to exhibit higher pATM and pATR staining than VM-negative specimens (r_s = 0.435, p < 0.001 and r_s = 0.317, p < 0.001). Besides, Hypoxia-inducible factor-1α (HIF1α) expression was detected in 14(10.3%) samples, correlated with higher WHO grade and non-frontal lobe (p = 0.010 and p = 0.029). However, no obvious connection was detected between HIF1α expression and VM formation (p = 0.537). Finally, either univariate or multivariate analysis suggested that VM was an independent unfavorable predictor for oligodendroglioma patients (p < 0.001, HR = 7.928, 95%CI: 3.382-18.584, and p = 0.007, HR = 4.534, 95%CI: 1.504-13.675, respectively). VM is a potential prognosticator for tumor progression in oligodendroglioma patients. Phosphorylation of ATM and ATR linked to treatment-resistance may be associated with VM formation. The role of VM in tumor progression and the implication of pATM/pATR in VM formation may provide potential therapeutic targets for oligodendroglioma treatment.

Cooperation Between Cancer and Fibroblasts in Vascular Mimicry and N2-Type Neutrophil Recruitment via Notch2-Jagged1 Interaction in Lung Cancer

Background

Angiogenesis is required for tumor development and metastasis, which is a major part in a pro-tumor microenvironment. Vascular mimicry (VM) is a process in which cancer cells, rather than endothelia, create an alternative perfusion system to support the tumor progression.

Objectives

To validate the role of VM and to develop a strategy to inhibit angiogenesis in lung cancer.

Methods

In this study, we utilized lung cancer samples to verify the existence of VM and conducted several experimental methods to elucidate the molecular pathways.

Results

H1299 and CL1-0 lung cancer cells were unable to form capillary-like structures. VM formation was induced by cancer-associated fibroblast (CAFs) in both in vitro and in vivo experiments. Notch2–Jagged1 cell–cell contact between cancer cells and CAFs contributes to the formation of VM networks, supported by Notch intracellular domain (NICD) 2 nuclear translocation and N2ICD target gene upregulated in lung cancer cells mixed with CAFs. The polarization of tumor-promoting N2-type neutrophil was increased by VM networks consisting of CAF and cancer cells. The intravasation of cancer cells and N2-type neutrophils were increased because of the loose junctions of VM. Disruption of cancer cell–CAF connections by a γ‐secretase inhibitor enforced the anticancer effect of anti‐vascular endothelial growth factor antibodies in a mouse model.

Conclusion

This study provides the first evidence that CAFs induce lung cancer to create vascular-like networks. These findings suggest a therapeutic opportunity for improving antiangiogenesis therapy in lung cancer.

A novel lncRNA, RPL34-AS1, promotes proliferation and angiogenesis in glioma by regulating VEGFA

Purpose: Brain gliomas are the most common primary malignant tumors of the central nervous system and one of the leading causes of death in patients with intracranial tumors. The lncRNA RPL34-AS1 is significantly upregulated in glioma tissues. However, the biological function of RPL34-AS1, especially in proliferation in glioma, remains unclear. Methods: The role of RPL34-AS1 in proliferation and angiogenesis in glioma cells was investigated using the LN229, U87, and U251 glioma cell lines. The levels of RPL34-AS1 were detected using real-time quantitative reverse transcription polymerase chain reaction. CCK-8 and colony formation assays were performed to determine the role of RPL34-AS1 in proliferation and survival, and its role in angiogenesis was assessed by an endothelial tube formation assay. Changes in protein levels were assessed by western blotting. Results: RPL34-AS1 was upregulated in glioma tissues and was correlated with tumor grade. RPL34-AS1 expression was also higher in glioma cells than in normal astrocytes. Knockdown of RPL34-AS1 blocked glioma cell proliferation by inhibiting angiogenesis. This effect occurred through decreased ERK/AKT signaling. Conclusions: This study suggests that RPL34-AS1 affects cell proliferation and angiogenesis in glioma and therefore may potentially serve as a valuable diagnostic and prognostic biomarker and therapeutic target in patients with glioma.

Advances in the role of autophagy in the development of retinoblastoma

Autophagy is a feedback regulatory mechanism of cells to external stress, which helps cells to adapt to changes in physiological conditions and environmental stress. Autophagy possesses a variety of target genes that control a wide range of signaling pathways. Maintenance of an appropriate level of autophagy is essential for the growth, metastasis and characteristics of tumors. Retinoblastoma (RB) is the most common primary intraocular malignant tumor found in the eyes of children following exposure to extreme environmental factors, such as mitochondrial defects, oxidative stress and excessive autophagy; this leads to the development of DNA damage and progressive loss of the function of the eye, which results in the occurrence of RB. Recent studies have documented the involvement of autophagy in the transformation, occurrence and metastasis of RB. High or low levels of autophagy exert notably promotive or repressive effects on the development, invasion, drug resistance and survival of RB, respectively. The present review reports the research progress on the association between autophagy and RB.

Inhibition of hsa_circ_0003489 shifts balance from autophagy to apoptosis and sensitizes multiple myeloma cells to bortezomib via miR-874-3p/HDAC1 axis

BACKGROUND

Circular RNAs (circRNAs) crucially regulate tumor progression. In this study, we examined the functional roles and mechanisms of hsa_circ_0003489 in multiple myeloma (MM).

METHODS

Upon altering the expressions of hsa_circ_0003489, miR-874-3p, and/or histone deacetylase 1 (HDAC1) in MM1.R cells and treating them with bortezomib (BTZ), cell viability was examined by CCK-8 assay; cell proliferation by Ki-67 immunofluorescence; apoptosis by TUNEL staining, flow cytometry, and western blot; and autophagy by electron microscopy and western blot. The interaction between hsa_circ_0003489 and miR-874-3p as well as that between miR-874-3p and HDAC1 was examined by expressional analysis, dual luciferase reporter assay, and RNA immunoprecipitation. The in vivo impacts of hsa_circ_0003489 on MM growth and sensitivity to BTZ were examined using an MM xenograft mouse model.

RESULTS

Knocking down hsa_circ_0003489 significantly inhibited the viability, cell proliferation, and autophagy, while promoting the apoptosis of MM cells in vitro and MM xenograft in vivo. Suppressing hsa_circ_0003489 also further boosted the cytotoxic effects of BTZ in MM cells and reversed its promoting effect on autophagy. Mechanically, hsa_circ_0003489 acted as a sponge of miR-874-3p and positively regulated the expression of miR-874-3p target, HDAC1. MiR-874-3p and HDAC1 essentially mediated the effects of hsa_circ_0003489 on cell viability, proliferation, apoptosis, and autophagy.

CONCLUSION

The hsa_circ_0003489/miR-874-3p/HDAC1 axis critically regulates the balance between apoptosis and autophagy. Silencing hsa_circ_0003489 sensitizes MM cells to BTZ by inhibiting autophagy and thus may boost the therapeutic effects of BTZ.

Dual role of WNT5A in promoting endothelial differentiation of glioma stem cells and angiogenesis of glioma derived endothelial cells

Glioma is a devastating cancer with a rich vascular network. No anti-angiogenic treatment is available for prolonging the overall survival of glioma patients. Recent studies have demonstrated that the endothelial differentiation of glioma stem cells (GSCs) into glioma-derived endothelial cells (GDECs) may be a novel target for anti-angiogenic therapy in glioma; however, the underlying mechanisms of this process remain unknown. Here, we report that wingless-related integration site (WNT) family member 5A (WNT5A) plays significant roles in GSC endothelial differentiation and GDECs angiogenesis. WNT5A is preferentially secreted by GDECs, and inhibition of WNT5A suppresses angiogenesis and tumorigenesis in GDECs. Silencing of WNT5A in GDECs also disrupts the impact of GDECs on stimulating GSC endothelial differentiation. Frizzled-4 is a receptor that mediates the effect of WNT5A on GSC endothelial differentiation and angiogenesis of GDECs via GSK3β/β-catenin/epithelial-mesenchymal transition signalling. The shWNT5A@cRGD-DDD liposomes, targeting WNT5A, exert anti-angiogenic effects in vivo. In this study, we identified that WNT5A has a dual functional role in modulating the endothelial differentiation of GSCs and angiogenesis of GDECs, indicating that WNT5A is a potential target for anti-angiogenesis-based therapeutics in glioma.