Exosomal transfer of miR-1238 contributes to temozolomide-resistance in glioblastoma

Exosomes derived from M2 type tumor-associated macrophages promote osimertinib resistance in non-small cell lung cancer through MSTRG.292666.16-miR-6836-5p-MAPK8IP3 axis

Background

Osimertinib resistance limits the treatment of epidermal growth factor receptor-(EGFR)-mutated non-small-cell lung carcinoma (NSCLC). The mechanisms of osimertinib resistance need to be elucidated to determine alternative treatment strategies. This study explores the role of M2 type tumor-associated macrophage (TAM)-derived exosomal MSTRG.292666.16 in osimertinib resistance, and its related competing endogenous RNA (ceRNA) mechanism.

Methods

M2 type TAMs were induced with 200 ng/mL phorbol 12-myristate 13-acetate, 20 ng/mL IL-4 and IL-13, and M2 type macrophage markers were measured by RT-qPCR. Next, the exosomes were isolated and characterized. Tumor formation in nude mice was conducted using H1975 cells under different treatment conditions. Small RNA sequencing was performed on exosomes derived from sensitive and resistant plasma, and ceRNA networks were constructed. Fluorescence in situ hybridization was used to observe the localization of MSTRG.292666.16, and a ceRNA network (MSTRG.292666.16-miR-6836-5p-MAPK8IP3) was selected for further validation.

Results

M2 type TAMs, and M2 type TAM-derived exosomes were successfully induced and isolated. Nude mice results showed that M2 type TAM-derived exosomes and MSTRG.292666.16 overexpression significantly increased tumor volume after administration of osimertinib for 4 weeks. M2 type TAMs were found in the resistant plasma, and MSTRG.292666.16 localized in the cytoplasm of H1975 cells. In addition, the genes in the ceRNA networks were significantly enriched in eight GO terms and seven KEGG pathways, including the MAPK signaling pathway. Subsequently, the levels of MSTRG.292666.16 and MAPK8IP3 significantly increased in both resistant plasma-derived exosomes and M2 type TAM-derived exosomes, while miR-6836-5p levels were significantly reduced. Finally, MSTRG.292666.16, miR-6836-5p, and MAPK8IP3 were part of the same network.

Conclusions

M2 type TAM-derived exosomes promoted osimertinib resistance in NSCLC by regulating the MSTRG.292666.16/miR-6386-5p/MAPK8IP3 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02509-x.

Glioblastoma-Astrocyte Connexin 43 Gap Junctions Promote Tumor Invasion

Glioblastoma multiforme (GBM), classified as World Health Organization grade IV astrocytoma, is the deadliest adult cancer of the central nervous system. An important contributing factor to poor survival rates in GBM is extensive invasion, which decreases the efficacy of resection and subsequent adjuvant therapies. These treatments could be markedly improved with increased resolution of the genetic and molecular initiators and effectors of invasion. Connexin 43 (Cx43) is the principal astrocytic gap junction (GJ) protein. Despite the heterogeneity of GBM, a subpopulation of cells in almost all GBM tumors express Cx43. Functional GJs between GBM cells and astrocytes at the tumor edge are of critical interest for understanding invasion. In this study, we find that both in vitro and in ex vivo slice cultures, GBM is substantially less invasive when placed in a Cx43-deficient astrocyte environment. Furthermore, when Cx43 is deleted in GBM, the invasive phenotype is recovered. These data strongly suggest that there are opposing roles for Cx43 in GBM migration. We find that Cx43 is localized to the tumor edge in our ex vivo model, suggesting that GBM-astrocyte GJ communication at the tumor border is a driving force for invasion. Finally, we find that by a Cx43-dependent mechanism, but likely not direct channel-mediated diffusion, miRNAs associated with cell-matrix adhesion are transferred from GBM to astrocytes and miR-19b promotes invasion, revealing a role for post-transcriptional manipulation of astrocytes in fostering an invasion-permissive peritumoral niche. IMPLICATIONS: Cx43-mediated communication, specifically miRNA transfer, profoundly impacts glioblastoma invasion and may enable further therapeutic insight.

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.

Caveolae-Associated Molecules, Tumor Stroma, and Cancer Drug Resistance: Current Findings and Future Perspectives

Simple Summary

Cell membranes contain small invaginations called caveolae. They are a specialized lipid domain and orchestrate cellular signaling events, mechanoprotection, and lipid homeostasis. Formation of the caveolae depends on two classes of proteins, the caveolins and cavins, which form large complexes that allow their self-assembly into caveolae. Loss of either of these two proteins leads to distortion of the caveolae structure and disruption of many physiological processes that affect diseases of the muscle, metabolic states governing lipids, and the glucose balance as well as cancers. In cancers, the expression of caveolins and cavins is heterogenous, and they undergo alterations both in the tumors and the surrounding tumor microenvironment stromal cells. Remarkably, their expression and function has been associated with resistance to many cancer drugs. Here, we summarize the current knowledge of the resistance mechanisms and how this knowledge could be applied into the clinic in future.

Abstract

The discovery of small, “cave-like” invaginations at the plasma membrane, called caveola, has opened up a new and exciting research area in health and diseases revolving around this cellular ultrastructure. Caveolae are rich in cholesterol and orchestrate cellular signaling events. Within caveola, the caveola-associated proteins, caveolins and cavins, are critical components for the formation of these lipid rafts, their dynamics, and cellular pathophysiology. Their alterations underlie human diseases such as lipodystrophy, muscular dystrophy, cardiovascular disease, and diabetes. The expression of caveolins and cavins is modulated in tumors and in tumor stroma, and their alterations are connected with cancer progression and treatment resistance. To date, although substantial breakthroughs in cancer drug development have been made, drug resistance remains a problem leading to treatment failures and challenging translation and bench-to-bedside research. Here, we summarize the current progress in understanding cancer drug resistance in the context of caveola-associated molecules and tumor stroma and discuss how we can potentially design therapeutic avenues to target these molecules in order to overcome treatment resistance.

Extracellular vesicles carry miR-27a-3p to promote drug resistance of glioblastoma to temozolomide by targeting BTG2

OBJECTIVE

Glioblastoma (GBM) is the most common central nervous system tumor. Temozolomide (TMZ) is a commonly used drug for GBM management. This study explored the mechanism of extracellular vesicles (EVs) regulating TMZ-resistance in GBM.

METHODS

LN229 cells were inducted into TMZ-resistant LN229r strain by stepwise induction. After the intervention of miR-27a-3p expression, cell viability of GBM cells treated with different concentrations of TMZ was detected by MTT and IC50 value was calculated. Cell proliferation and apoptosis were detected by colony formation and flow cytometry. EVs extracted from LN18 cells were identified and the internalization of EVs by LN229r cells was evaluated. The 100 μmol/L TMZ-treated LN229r cells were treated with EVs or EVs with downregulated miR-27a-3p to verify the effect of EVs-carried miR-27a-3p on TMZ resistance. The binding relation between BTG2 and miR-27a-3p was verified. miR-27a-3p and BTG2 expressions in GBM cells and EVs were detected by RT-qPCR. The BTG2 effect on TMZ-resistance in GBM was verified. The xenograft tumor nude mouse model was established by injecting LN229r cells and treated with EVs and 100 μmol/L TMZ.

RESULTS

miR-27a-3p was highly expressed in LN229r cells. IC50 value and proliferation of LN229r cells with silenced miR-27a-3p were decreased and apoptosis was increased, indicating that miR-27a-3p silencing reduced the drug-resistant cell LN229r resistance to TMZ. LN18-derived EVs could be internalized by LN229r cells, and release its encapsulated miR-27a-3p into LN229r cells and increase miR-27a-3p expression. EV treatment increased LN229r cell proliferation and reduced apoptosis, while EVs with silenced miR-27a-3p showed the opposite trend. miR-27a-3p targeted BTG2. BTG2 overexpression reduced LN229r cell resistance to TMZ. In vivo, after EVs treatment, tumor volume and weight, Ki67-positive rate, and miR-27a-3p were increased, while BTG2 expression was decreased.

CONCLUSION

GBM-derived EVs were internalized by GBM cells, released miR-27a-3p into GBM cells, upregulated miR-27a-3p expression, and targeted BTG2, thus promoting TMZ resistance.

WNT signaling modulates chemoresistance to temozolomide in p53-mutant glioblastoma multiforme

Glioblastoma multiforme (GBM) has been characterized by the high incidence, therapy tolerance and relapse. The molecular events controlling GBM resistant to chemotherapy temozolomide (TMZ) remain to be elusive. Here, we identified WNT signaling was amplified by TMZ and mediated drug response in GBM. We found O6-methylguanine DNA methyltransferase (MGMT) was redundant to WNT-mediated chemoresistance, which was highly associated with p53 mutation status. In GBM with p53 mutation, loss of function of p53 downregulated miR-34a expression, which represses transcription of WNT ligand 6 (WNT6) by directly binding to 3' UTR of WNT6 mRNA, leading to activation of WNT signaling, and the eventual WNT-mediated chemoresistance to TMZ. Combined treatment of TMZ with WNT inhibitor or miR34a mimic induced drug sensitivity of p53-mutant GBM cells and extended survival in xenograft mice in vivo. Our findings provide insight into understanding the molecular mechanism of GBM chemoresistance to TMZ and facilitating to develop novel treatment strategy to combat p53-mutant GBM by targeting miR-34a/WNT6 axis.

Dynamic Intercell Communication between Glioblastoma and Microenvironment through Extracellular Vesicles

Glioblastoma is simultaneously the most common and most aggressive primary brain tumor in the central nervous system, with poor patient survival and scarce treatment options. Most primary glioblastomas reoccur and evolve radio- and chemoresistant properties which make them resistant to further treatments. Based on gene mutations and expression profiles, glioblastoma is relatively well classified; however, research shows that there is more to glioblastoma biology than that defined solely by its genetic component. Specifically, the overall malignancy of the tumor is also influenced by the dynamic communication to its immediate and distant environment, as important messengers to neighboring cells in the tumor microenvironment extracellular vesicles (EVs) have been identified. EVs and their cargo can modulate the immune microenvironment and other physiological processes, and can interact with the host immune system. They are involved in tumor cell survival and metabolism, tumor initiation, progression, and therapy resistance. However, on the other hand EVs are thought to become an effective treatment alternative, since they can cross the blood–brain barrier, are able of specific cell-targeting and can be loaded with various therapeutic molecules.

Network Pharmacology and Inflammatory Microenvironment Strategy Approach to Finding the Potential Target of Siraitia grosvenorii (Luo Han Guo) for Glioblastoma

Background: Glioblastoma (GBM) is the most common and aggressive primary intracranial tumor of the central nervous system, and the prognosis of GBM remains a challenge using the standard methods of treatment—TMZ, radiation, and surgical resection. Traditional Chinese medicine (TCM) is a helpful complementary and alternative medicine. However, there are relatively few studies on TCM for GBM.

Purpose: We aimed to find the connection between TCM and anti-GBM.

Study design: Network pharmacology and inflammatory microenvironment strategy were used to predict Siraitia grosvenorii (Luo Han Guo) target for treating glioblastoma.

Methods: We mainly used network pharmacology and bioinformatics.

Results: CCL5 was significantly highly expressed in GBM with poor prognostics. Uni-cox and randomForest were used to determine that CCL5 was especially a biomarker in GBM. CCL5 was also the target for SG and TMZ. The active ingredient of Luo Han Guo — squalene and CCL5 —showed high binding efficiency. CCL5, a chemotactic ligand, was enriched and positively correlated in eosinophils. CCL5 was also the target of Luo Han Guo, and its effective active integrate compound –— squalene — might act on CCL5.

Conclusion: SG might be a new complementary therapy of the same medicine and food, working on the target CCL5 and playing an anti-GBM effect. CCL5 might affect the immune microenvironment of GBM.

[Extracellular vesicles in the central nervous system]

Extracellular Vesicles (EVs) are released by a wide diversity of cells. They contain proteins, RNAs and lipids that will be exchanged between these cells. They represent therefore a major form of intercellular communication in both physiological and pathological conditions. This is particularly relevant in the nervous system where neurons and glial cells form a very dense network where billions of connections are made. In this review, the different roles played by the EVs in a healthy brain to maintain cerebral homeostasis during development, synaptic transmission or axonal myelination will be discussed. In addition, the pathological aspects of EVs presence will also be addressed. In recent years, the EVs have emerged as major players in the spread of neurodegenerative diseases, in neuroinflammation and in tumor development, although they may also be beneficial in some conditions.

Silencing lncRNA LINC01410 suppresses cell viability yet promotes apoptosis and sensitivity to temozolomide in glioblastoma cells by inactivating PTEN/AKT pathway via targeting miR-370-3p

BACKGROUND

Long non-coding RNAs (LncRNAs) are involved in glioblastoma (GBM), but the role of long intergenic non-protein coding RNA 01410 (lncRNA LINC01410) is poorly understood.

METHODS

The expression of LINC01410 in GBM tissues and cells was analyzed. After transfection or temozolomide (TMZ) treatment, the cell viability and apoptosis were detected using cell counting kit-8 assay and flow cytometry. The targeting relationship between LINC01410 and microRNA (miR)-370-3p was confirmed by dual-luciferase reporter assay. Expressions of LINC01410, miR-370-3p and drug resistance- and Phosphatase and Tensin Homolog (PTEN)/AKT pathway-related factors were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot.

RESULTS

LINC01410 expression was upregulated in GBM, and silencing of LINC01410 decreased cell viability. A slowed decreased trend in cell viability yet an increased half maximal inhibitory concentration (IC50 for TMZ) value and increased expressions of drug resistance-related factors as well as LINC01410 were found in TMZ-resistant GBM cells. Silencing of LINC01410 also decreased the IC50 value yet promoted the sensitivity and apoptosis in TMZ-resistant cells, while upregulating the expression of PTEN and downregulating the phosphorylation of AKT. MiR-370-3p could competitively bind to LINC01410 and its expression was decreased in both parental and TMZ-resistant GBM cells. Downregulation of miR-370-3p reversed the effects of LINC01410 silencing on cell viability, apoptosis and the expressions of miR-370-3p and PTEN/AKT pathway-related factors.

CONCLUSION

Silencing of LINC01410 inhibits cell viability yet enhances apoptosis and sensitivity to TMZ in GBM cells by inactivating PTEN/AKT pathway via targeting miR-370-3p.

Gastrointestinal cancer drug resistance: the role of exosomal miRNAs

Resistance of gastrointestinal (GI) cancer cells to therapeutic agents are one of the major problems in treating this type of cancer. Although the exact mechanism of drug resistance has not yet been fully elucidated, various factors have been identified as contributing factors involved in this process. Several studies have revealed the role of exosomes, especially exosomal microRNAs (miRNAs), in GI tumorigenesis, invasion, angiogenesis, and drug resistance. Exosomes, a type of small extracellular vesicles (EVs), are originated from endosomes and are released into the extracellular environment and body fluids by different cell types. Exosomes mediate cell-cell communication by transferring different cargos, including miRNAs, between parent and recipient cells. Therefore, identifying these exosomal miRNAs and their functions in GI cancers might provide new clues to further explore the secret of this process and thus help in drug-resistance management. This review article will discuss the roles of exosomal miRNAs and their mechanisms of action in drug resistance of different types of GI cancer cells (e.g., stomach, esophagus, liver, pancreas, and colon) to therapeutic agents.

miRNA-338-3p inhibits glioma cell proliferation and progression by targeting MYT1L

Glioma is a common and aggressive primary malignant brain tumor. MicroRNAs (miRNAs) play key roles in the post-transcriptional regulation of gene expression. Currently, miRNAs are considered to be useful biomarkers for the diagnosis and prognosis of glioma. Previously, we screened three differentially expressed miRNAs from Gene Expression Omnibus (GEO) database which included miRNA-338-3p. miRNA-338-3p is involved in tumor development in different cancers. However, in glioma, its function and its underlying mechanism remain unclear. We found that overexpression of miRNA-338-3p suppressed cell proliferation, migration, invasion, and promoted apoptosis of glioma in vitro. Myelin transcription factor 1-like (MYT1L) was found to be a direct target of miRNA-383-3p in glioma cells as the expression of MYT1L was inhibited by overexpressing miRNA-338-3p. Additionally, silencing MYT1L produced similar effects as overexpressing miRNA-338-3p in glioma cells. Overexpression of MYT1L also completely attenuated the inhibitory effect induced by miRNA-338-3p overexpression. These results suggest that the miRNA-338-3p/ MYT1L axis plays a critical role in the progression of glioma. Our study delineates one of the complex molecular mechanisms that drive the growth of glioma and may be useful in finding novel prognostic predictors and treatment targets in glioma. AVAILABILITY OF DATA AND MATERIALS: All data generated or analysed during this study are included in this published article.

The multifaceted involvement of exosomes in tumor progression: Induction and inhibition

As key performers in intercellular communication, exosomes released by tumor cells play an important role in cancer development, including angiogenesis, cancer‐associated fibroblasts activation, epithelial‐mesenchymal transformation (EMT), immune escape, and pre‐metastatic niche formation. Meanwhile, other cells in tumor microenvironment (TME) can secrete exosomes and facilitate tumor progression. Elucidating mechanisms regarding these processes may offer perspectives for exosome‐based antitumor strategies. In this review, we mainly introduce the versatile roles of tumor or stromal cell derived exosomes in cancer development, with a particular focus on the biological capabilities and functionalities of their diverse contents, such as miRNAs, lncRNAs, and circRNAs. The potential clinical application of exosomes as biomarkers in cancer diagnosis and prognosis is also discussed. Finally, the current antitumor strategies based on exosomes in immunotherapy and targeted delivery for chemotherapeutic or biological agents are summarized.

Research Progress on Circular RNA in Glioma

The discovery of circular RNA (circRNA) greatly complements the traditional gene expression theory. CircRNA is a class of non-coding RNA with a stable cyclic structure. They are highly expressed, spatiotemporal-specific and conservative across species. Importantly, circRNA participates in the occurrence of many kinds of tumors and regulates the tumor development. Glioma is featured by limited therapy and grim prognosis. Cancer-associated circRNA compromises original function or creates new effects in glioma, thus contributing to oncogenesis. Therefore, this article reviews the biogenesis, metabolism, functions and properties of circRNA as a novel potential biomarker for gliomas. We elaborate the expression characteristics, interaction between circRNA and other molecules, aiming to identify new targets for early diagnosis and treatment of gliomas.

Circulating MicroRNAs in Relation to Esophageal Adenocarcinoma Diagnosis and Survival

BACKGROUND AND AIMS

Tissue miRNA can discriminate between esophageal adenocarcinoma (EA) and normal epithelium. However, no studies have examined a comprehensive panel of circulating miRNAs in relation to EA diagnosis and survival.

METHODS

We used all 62 EA cases from the US Multi-Center case-control study with available serum matched 1:1 to controls. Cases were followed for vital status. MiRNAs (n = 2064) were assessed using the HTG EdgeSeq miRNA Whole Transcriptome Assay. Differential expression analysis of miRNAs in relation to case-control status was conducted. In cases, Cox regression models were fit to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality. P values were adjusted using the Benjamini-Hochberg (BH) procedure for false discovery rate control. Predictive performance was assessed using cross-validation.

RESULTS

Sixty-eight distinct miRNAs were significantly upregulated between cases and controls (e.g., miR-1255b-2-3p fold change = 1.74, BH-adjusted P = 0.01). Assessing the predictive performance of these significantly upregulated miRNAs yielded 60% sensitivity, 65% specificity, and 0.62 AUC. miR-4253 and miR-1238-5p were associated with risk of mortality after EA diagnosis (HR = 4.85, 95% CI: 2.30-10.23, BH-adjusted P = 0.04 and HR = 3.81, 95% CI: 2.02-7.19, BH-adjusted P = 0.04, respectively).

CONCLUSIONS

While they require replication, these findings suggest that circulating miRNAs may be associated with EA diagnosis and survival.

Glioblastoma Cell-Derived lncRNA-Containing Exosomes Induce Microglia to Produce Complement C5, Promoting Chemotherapy Resistance

Glioblastoma (GBM), the most common malignant primary brain cancer in adults, nearly always becomes resistant to current treatments, including the chemotherapeutic temozolomide (TMZ). The long noncoding RNA (lncRNA) TMZ-associated lncRNA in GBM recurrence (lnc-TALC) promotes GBM resistance to TMZ. Exosomes can release biochemical cargo into the tumor microenvironment (TME) or transfer their contents, including lncRNAs, to other cells as a form of intercellular communication. In this study, we found that lnc-TALC could be incorporated into exosomes and transmitted to tumor-associated macrophages (TAM) and could promote M2 polarization of the microglia. This M2 polarization correlated with secretion of the complement components C5/C5a, which occurred downstream of lnc-TALC binding to ENO1 to promote the phosphorylation of p38 MAPK. In addition, C5 promoted the repair of TMZ-induced DNA damage, leading to chemotherapy resistance, and C5a-targeted immunotherapy showed improved efficacy that limited lnc-TALC-mediated TMZ resistance. Our results reveal that exosome-transmitted lnc-TALC could remodel the GBM microenvironment and reduce tumor sensitivity to TMZ chemotherapy, indicating that the lnc-TALC-mediated cross-talk between GBM cells and microglia could attenuate chemotherapy efficacy and pointing to potential combination therapy strategies to overcome TMZ resistance in GBM.See related Spotlight by Zhao and Xie, p. 1372.

The Roles of Exosomes as Future Therapeutic Agents and Diagnostic Tools for Glioma

Glioma is a common type of tumor originating in the brain. Glioma develops in the gluey supporting cells (glial cells) that surround and support nerve cells. Exosomes are extracellular vesicles that contain microRNAs, messenger RNA, and proteins. Exosomes are the most prominent mediators of intercellular communication, regulating, instructing, and re-educating their surrounding milieu targeting different organs. As exosomes' diameter is in the nano range, the ability to cross the blood-brain barrier, a crucial obstacle in developing therapeutics against brain diseases, including glioma, makes the exosomes a potential candidate for delivering therapeutic agents for targeting malignant glioma. This review communicates the current knowledge of exosomes' significant roles that make them crucial future therapeutic agents and diagnostic tools for glioma.

The Role of MicroRNAs in Therapeutic Resistance of Malignant Primary Brain Tumors

Brain tumors in children and adults are challenging tumors to treat. Malignant primary brain tumors (MPBTs) such as glioblastoma have very poor outcomes, emphasizing the need to better understand their pathogenesis. Developing novel strategies to slow down or even stop the growth of brain tumors remains one of the major clinical challenges. Modern treatment strategies for MPBTs are based on open surgery, chemotherapy, and radiation therapy. However, none of these treatments, alone or in combination, are considered effective in controlling tumor progression. MicroRNAs (miRNAs) are 18-22 nucleotide long endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level by interacting with 3'-untranslated regions (3'-UTR) of mRNA-targets. It has been proven that miRNAs play a significant role in various biological processes, including the cell cycle, apoptosis, proliferation, differentiation, etc. Over the last decade, there has been an emergence of a large number of studies devoted to the role of miRNAs in the oncogenesis of brain tumors and the development of resistance to radio- and chemotherapy. Wherein, among the variety of molecules secreted by tumor cells into the external environment, extracellular vesicles (EVs) (exosomes and microvesicles) play a special role. Various elements were found in the EVs, including miRNAs, which can be transported as part of these EVs both between neighboring cells and between remotely located cells of different tissues using biological fluids. Some of these miRNAs in EVs can contribute to the development of resistance to radio- and chemotherapy in MPBTs, including multidrug resistance (MDR). This comprehensive review examines the role of miRNAs in the resistance of MPBTs (e.g., high-grade meningiomas, medulloblastoma (MB), pituitary adenomas (PAs) with aggressive behavior, and glioblastoma) to chemoradiotherapy and pharmacological treatment. It is believed that miRNAs are future therapeutic targets in MPBTs and such the role of miRNAs needs to be critically evaluated to focus on solving the problems of resistance to therapy this kind of human tumors.

The alerting expression of microRNA-411 predicts clinical prognosis and regulates tumor progression of glioblastoma

Glioblastoma is a malignant intracranial tumor with indispensable growth. Identification of biomarkers associated with the progression of tumors could benefit the clinical therapy of and improve patient’s survival. miR-411 has been reported to play a role in other cancers, while its function in glioblastoma has been explored in the present study. The expression of miR-411 was evaluated in glioblastoma tissues (collected from 108 glioblastoma patients) and cells by polymerase chain reaction. The clinical significance of miR-411 was estimated with a series of statistical analyses. The biological function of miR-411 in the cellular processes of glioblastoma was assessed by cell counting kit 8 and Transwell assay. The expression of miR-411 was significantly reduced in glioblastoma, which was associated with the Karnofsky Performance Score (KPS) and Isocitrate dehydrogenase 1 (IDH1) status of patients. miR-411 was identified as an independent prognostic indicator that correlated with the poor prognosis of patients. miR-411 suppressed the growth, migration, and invasion of glioblastoma cells via modulating signal transducer and activator of transcription 3 (STAT3). miR-411 participated in the development of glioblastoma and function as a prognostic biomarker. miR-411 functions as a tumor suppressor, which provides a novel potential therapeutic target for glioblastoma.

Liquid Biopsy in Glioblastoma Management: From Current Research to Future Perspectives

Glioblastoma (GBM) is the most common primary tumor of the central nervous system. Arising from neuroepithelial glial cells, GBM is characterized by invasive behavior, extensive angiogenesis, and genetic heterogeneity that contributes to poor prognosis and treatment failure. Currently, there are several molecular biomarkers available to aid in diagnosis, prognosis, and predicting treatment outcomes; however, all require the biopsy of tumor tissue. Nevertheless, a tissue sample from a single location has its own limitations, including the risk related to the procedure and the difficulty of obtaining longitudinal samples to monitor treatment response and to fully capture the intratumoral heterogeneity of GBM. To date, there are no biomarkers in blood or cerebrospinal fluid for detection, follow-up, or prognostication of GBM. Liquid biopsy offers an attractive and minimally invasive solution to support different stages of GBM management, assess the molecular biology of the tumor, identify early recurrence and longitudinal genomic evolution, predict both prognosis and potential resistance to chemotherapy or radiotherapy, and allow patient selection for targeted therapies. The aim of this review is to describe the current knowledge regarding the application of liquid biopsy in glioblastoma, highlighting both benefits and obstacles to translation into clinical care. IMPLICATIONS FOR PRACTICE: To translate liquid biopsy into clinical practice, further prospective studies are required with larger cohorts to increase specificity and sensitivity. With the ever-growing interest in RNA nanotechnology, microRNAs may have a therapeutic role in brain tumors.

Exosome-mediated transfer of MIF confers temozolomide resistance by regulating TIMP3/PI3K/AKT axis in gliomas

Temozolomide (TMZ) resistance is an important cause of clinical treatment failure and poor prognosis in gliomas. Increasing evidence indicates that cancer-derived exosomes contribute to chemoresistance; however, the specific contribution of glioma-derived exosomes remains unclear. The aim of this study was to explore the role and underlying mechanisms of exosomal macrophage migration inhibitory factor (MIF) on TMZ resistance in gliomas. We first demonstrated that MIF was upregulated in the exosomes of TMZ-resistant cells, engendering the transfer of TMZ resistance to sensitive cells. Our results indicated that exosomal MIF conferred TMZ resistance to sensitive cells through the enhancement of cell proliferation and the repression of cell apoptosis upon TMZ exposure. MIF knockdown enhanced TMZ sensitivity in resistant glioma cells by upregulating Metalloproteinase Inhibitor 3 (TIMP3) and subsequently suppressing the PI3K/AKT signaling pathway. Additionally, exosomal MIF promoted tumor growth and TMZ resistance of glioma cells in vivo, while IOS-1 (MIF inhibitor) promotes glioma TMZ sensitive in vivo. Taken together, our study demonstrated that exosome-mediated transfer of MIF enhanced TMZ resistance in glioma through downregulating TIMP3 and further activating the PI3K/AKT signaling pathway, highlighting a prognostic biomarker and promising therapeutic target for TMZ treatment in gliomas.

A novel lncRNA-mRNA-miRNA signature predicts recurrence and disease-free survival in cervical cancer

Cervical cancer (CC) patients have a poor prognosis due to the high recurrence rate. However, there are still no effective molecular signatures to predict the recurrence and survival rates for CC patients. Here, we aimed to identify a novel signature based on three types of RNAs [messenger RNA (mRNAs), microRNA (miRNAs), and long non-coding RNAs (lncRNAs)]. A total of 763 differentially expressed mRNAs (DEMs), 46 lncRNAs (DELs), and 22 miRNAs (DEMis) were identified between recurrent and non-recurrent CC patients using the datasets collected from the Gene Expression Omnibus (GSE44001; training) and The Cancer Genome Atlas (RNA- and miRNA-sequencing; testing) databases. A competing endogenous RNA network was constructed based on 23 DELs, 15 DEMis, and 426 DEMs, in which 15 DELs, 13 DEMis, and 390 DEMs were significantly associated with disease-free survival (DFS). A prognostic signature, containing two DELs (CD27-AS1, LINC00683), three DEMis (hsa-miR-146b, hsa-miR-1238, hsa-miR-4648), and seven DEMs (ARMC7, ATRX, FBLN5, GHR, MYLIP, OXCT1, RAB39A), was developed after LASSO analysis. The built risk score could effectively separate the recurrence rate and DFS of patients in the high- and low-risk groups. The accuracy of this risk score model for DFS prediction was better than that of the FIGO (International Federation of Gynecology and Obstetrics) staging (the area under receiver operating characteristic curve: training, 0.954 vs 0.501; testing, 0.882 vs 0.656; and C-index: training, 0.855 vs 0.539; testing, 0.711 vs 0.508). In conclusion, the high predictive accuracy of our signature for DFS indicated its potential clinical application value for CC patients.

The Role of Exosomal miRNAs in Glioma: Biological Function and Clinical Application

Gliomas are complex and heterogeneous central nervous system tumors with poor prognosis. Despite the increasing development of aggressive combination therapies, the prognosis of glioma is generally unsatisfactory. Exosomal microRNA (miRNA) has been successfully used in other diseases as a reliable biomarker and even therapeutic target. Recent studies show that exosomal miRNA plays an important role in glioma occurrence, development, invasion, metastasis, and treatment resistance. However, the association of exosomal miRNA between glioma has not been systemically characterized. This will provide a theoretical basis for us to further explore the relationship between exosomal miRNAs and glioma and also has a positive clinical significance in the innovative diagnosis and treatment of glioma.

MicroRNA-550a-3-5p controls the brain metastasis of lung cancer by directly targeting YAP1

Background

This study aimed to explore the potential regulatory mechanisms of brain metastasis and to identify novel underlying targets of lung cancer with brain metastasis.

Methods

Exosomes were isolated from the plasma of lung cancer patients with or without brain metastasis and low or high metastatic lung cancer cells, and small RNA from plasma-derived exosomes were sequenced. Differentially expressed miRNAs (DE-miRNAs) were identified. Human brain microvascular endothelial cells (HBMECs) were transfected with miR-550a-3-5p mimics or inhibitors and exosomes. Cell viability, migration, and apoptosis/cycle were determined using Cell Counting Kit-8 (CCK-8), Transwell, and flow cytometry, respectively. Western blotting was used to measure the expression of the associated proteins. Finally, a dual-luciferase reporter gene assay was performed to confirm the miR-550a-3-5p target.

Results

Transmission electron microscopy, NanoSight, and western blotting showed that exosomes were successfully isolated and cell-derived exosomes could be taken up by HBMECs. Sequencing identified 22 DE-miRNAs which were enriched in the MAPK, chemokine, PPAR, and Wnt signaling pathways. MiR-550a-3-5p was significantly enriched in brain metastatic exosomes. Cellular experiments showed that miR-550a-3-5p and exosome enrichment significantly inhibited cell viability and migration, promoted apoptosis, and regulated the cell cycle of HBMECs compared with the controls (P  <  0.05). Compared with the controls, high levels of both miR-550a-3-5p and exosomes markedly upregulated cleaved-PARP expression, but downregulated the expression of pRB, CDK6, YAP1, CTGF, and CYR61 (P  <  0.05). Finally, YAP1 was confirmed to bind directly to miR-550a-3-5p.

Conclusion

Our results indicate that miR-550a-3-5p and YAP1 may be novel potential targets for controlling brain metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02197-z.

The IL13α 2R paves the way for anti-glioma nanotherapy

Glioblastoma (GBM) is one of the most aggressive (grade IV) gliomas characterized by a high rate of recurrence, resistance to therapy and a grim survival prognosis. The long-awaited improvement in GBM patients' survival rates essentially depends on advances in the development of new therapeutic approaches. Recent preclinical studies show that nanoscale materials could greatly contribute to the improvement of diagnosis and management of brain cancers. In the current review, we will discuss how specific features of glioma pathobiology can be employed for designing efficient targeting approaches. Moreover, we will summarize the main evidence for the potential of the IL-13R alpha 2 receptor (IL13α2R) targeting in GBM early diagnosis and experimental therapy.

Circulating Exosomal MicroRNA Profiles Associated with Acute Soft Tissue Injury

Objective

This study aimed to characterize the circulating exosomal microRNA (miRNA) profiles associated with acute soft tissue injury.

Materials and Methods

In this experimental study, a total of 12 rats were randomly divided into control group and model group (n=6 for each group). The rats in the model group were used to establish an acute soft tissue injury following the mechanical injury of the leg. The exosomes from the peripheral blood of all the rats were isolated and then characterized by Nanosight NS300 particle size analyser (NTA), transmission electron microscopy (TEM) and western blot. Next, the exosomal miRNAs in the control and model groups were sequenced, and the differentially expressed miRNAs (DE-miRNAs) were identified using the DESeq algorithm. Functional analyses were performed using Gene Ontology (GO) terms and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway databases. Finally, quantitative reverse-transcription polymersa chain reaction (qRT-PCR) was used to verify the expression of the DE-miRNAs.

Results

TEM, NTA and western blot results showed that the exosomes were approximately 100 nm in size and exhibited cup-shaped morphology. A total of 628 miRNAs were obtained by sequencing. After that, 28 DE miRNAs (DEmiRNAs) were identified, including seven down-regulated miRNAs and 21 up-regulated miRNAs. These DE-miRNAs were linked to 7539 target genes with GO. Also, KEGG analyses demonstrated that these genes were enriched for phosphorylation, VEGF signaling pathway, and MAPK signaling pathway. Additionally, the consistency rate between the qRT-PCR and sequencing results was 83.33%, which showed a high relative reliability of the sequencing results.

Conclusion

These findings suggest that these 28 exosomal miRNAs may be involved in the regulation of acute soft tissue injury, by one of critical biological processes (BP), phosphorylation. The findings provide valuable clues by utilizing exosomes as therapeutic targets for the effective treatment of acute soft tissue injury.

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

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

Exosomal transfer of miR‑25‑3p promotes the proliferation and temozolomide resistance of glioblastoma cells by targeting FBXW7

Intrinsic or acquired resistance to temozolomide (TMZ) is a frequent occurrence in patients with glioblastoma (GBM). Accumulating evidence has indicated that the exosomal transfer of proteins and RNAs may confer TMZ resistance to recipient cells; however, the potential molecular mechanisms are not fully understood. Thus, the aim of the present study was to elucidate the possible role of exosomal microRNAs (miRNAs/miRs) in the acquired resistance to TMZ in GBM. A TMZ-resistant GBM cell line (A172R) was used, and exosomes derived from A172R cells were extracted. Exosomal miR-25-3p was identified as a miRNA associated with TMZ resistance. The potential functions of exosomal miR-25-3p were evaluated by reverse transcription-quantitative PCR, as well as cell viability, colony formation and soft agar assay, flow cytometry, western blot analysis, BrdU incorporation assay, tumor xenograft formation, luciferase reporter assay and RNA immunoprecipitation. It was found that A172R-derived exosomes promoted the proliferation and TMZ resistance of sensitive GBM cells. Moreover, miR-25-3p epxression was upregulated in the exosomes of A172R cells and in serum samples of patients with GBM treated with TMZ. The depletion of exosomal miR-25-3p partially abrogated the effects induced by the transfer of exosomes from A172R cells. By contrast, miR-25-3p overexpression facilitated the proliferation and TMZ resistance of sensitive GBM cells. F-box and WD repeat domain-containing-7 (FBXW7) was identified as a direct target of miR-25-3p. FBXW7 knockdown promoted the proliferation and TMZ resistance of GBM cells. Furthermore, the exosomal transfer of miR-25-3p promoted c-Myc and cyclin E expression by downregulating FBXW7. Our results provided a novel insight into exosomal microRNAs in acquired TMZ resistance of GBM cells. Besides, exosomal miR-25-3p might be a potential prognostic marker for GBM patients.

Exosomal noncoding RNAs: key players in glioblastoma drug resistance

Glioma, as one of the most severe human malignancies, is defined as the Central Nervous System's (CNS) tumors. Glioblastoma (GBM) in this regard, is the most malignant type of gliomas. There are multiple therapeutic strategies to cure GBM, for which chemotherapy is often the first-line treatment. Still, various cellular processes, such as uncontrolled proliferation, invasion and metastasis, may disturb the treatment efficacy. Drug resistance is another process in this way, which can also cause undesirable effects. Thereupon, identifying the mechanisms, involved in developing drug resistance and the relevant mechanisms can be very helpful in GBM management. The discovery of exosomal non-coding RNAs (ncRNAs), RNA molecules that can be transferred between the cells and different tissues using the exosomes, was a milestone in this regard. It has been revealed that the key exosomal ncRNAs, including circular RNAs, microRNAs, and long ncRNAs, are able to modulate GBM drug resistance through different signaling pathways or by affecting regulatory proteins and their corresponding genes. Nowadays, researchers are trying to overcome the limitations of chemotherapy by targeting these RNA molecules. Accordingly, this review aims to clarify the substantial roles of exosomal ncRNAs in GBM drug resistance and involved mechanisms.

The Multifaceted Role of Extracellular Vesicles in Glioblastoma: microRNA Nanocarriers for Disease Progression and Gene Therapy

Glioblastoma (GB) is the most aggressive form of brain cancer in adults, characterized by poor survival rates and lack of effective therapies. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression post-transcriptionally through specific pairing with target messenger RNAs (mRNAs). Extracellular vesicles (EVs), a heterogeneous group of cell-derived vesicles, transport miRNAs, mRNAs and intracellular proteins, and have been shown to promote horizontal malignancy into adjacent tissue, as well as resistance to conventional therapies. Furthermore, GB-derived EVs have distinct miRNA contents and are able to penetrate the blood-brain barrier. Numerous studies have attempted to identify EV-associated miRNA biomarkers in serum/plasma and cerebrospinal fluid, but their collective findings fail to identify reliable biomarkers that can be applied in clinical settings. However, EVs carrying specific miRNAs or miRNA inhibitors have great potential as therapeutic nanotools in GB, and several studies have investigated this possibility on in vitro and in vivo models. In this review, we discuss the role of EVs and their miRNA content in GB progression and resistance to therapy, with emphasis on their potential as diagnostic, prognostic and disease monitoring biomarkers and as nanocarriers for gene therapy.

A novel miR1983-TLR7-IFNβ circuit licenses NK cells to kill glioma cells, and is under the control of galectin-1

Although pharmacological stimulation of TLRs has anti-tumor effects, it has not been determined whether endogenous stimulation of TLRs can lead to tumor rejection. Herein, we demonstrate the existence of an innate anti-glioma NK-mediated circuit initiated by glioma-released miR-1983 within exosomes, and which is under the regulation of galectin-1 (Gal-1). We demonstrate that miR-1983 is an endogenous TLR7 ligand that activates TLR7 in pDCs and cDCs through a 5'-UGUUU-3' motif at its 3' end. TLR7 activation and downstream signaling through MyD88-IRF5/IRF7 stimulates secretion of IFN-β. IFN-β then stimulates NK cells resulting in the eradication of gliomas. We propose that successful immunotherapy for glioma could exploit this endogenous innate immune circuit to activate TLR7 signaling and stimulate powerful anti-glioma NK activity, at least 10-14 days before the activation of anti-tumor adaptive immunity.

Myocardial Infarction-Associated Extracellular Vesicle-Delivered miR-208b Affects the Growth of Human Umbilical Vein Endothelial Cells via Regulating CDKN1A

This study was aimed at investigating the effects of myocardial infarction- (MI-) associated extracellular vesicle- (EV-) delivered miR-208b on human umbilical vein endothelial cells (HUVECs). EVs were isolated and subsequently stained with PHK67. A dual-luciferase reporter gene assay was used to determine the target of miR-208b. Afterwards, HUVECs were transfected with either MI-associated EVs or miR-208b mimics, and cell viability, migration, and apoptosis were subsequently measured. Real-time quantitative polymerase chain reaction (RT-qPCR) was applied to determine the expressions of the tested genes. NanoSight, transmission electron microscopy, and western blotting showed that EVs were successfully isolated. Among the potential microRNA biomarkers for MI, miR-208b was chosen for subsequent experiments. We found that MI-associated EVs could be taken up by HUVECs and confirmed that CDKN1A was a direct target of miR-208b. Additionally, miR-208b mimics and MI-associated EVs significantly inhibited the viability and migration of HUVECs (P < 0.05) and promoted cell apoptosis, as well as reduced S phase and increased G2/M phase cell distribution. RT-qPCR revealed that both miR-208b mimics and MI-associated EVs upregulated the expressions of CDKN1A, FAK, Raf-1, MAPK1, and Bax but downregulated the expression of Bcl2 and reduced the Bcl2/Bax ratio. Our study concludes that MI-associated EVs delivered miR-208b to HUVECs, and EV-delivered miR-208b could affect the growth of HUVECs by regulating the miR-208b/CDKN1A pathway; thus, miR-208b can be therefore served as important therapeutic targets for MI treatment.

Exosomes Isolated From Bone Marrow Mesenchymal Stem Cells Exert a Protective Effect on Osteoarthritis via lncRNA LYRM4-AS1-GRPR-miR-6515-5p

Objectives

The aim of this study was to investigate the effects of exosomes isolated from human bone marrow mesenchymal stem cells (BMSCs) on osteoarthritis (OA) and a competitive endogenous RNA (ceRNA) network.

Methods

Exosomes were isolated from human BMSCs and characterized by transmission electron microscopy (TEM), Nanosight (NTA), and western blotting. Chondrocytes were treated with interleukin-1β (IL-1β) and then transfected with exosomes. Cell viability and apoptosis were determined using Cell Counting Kit-8 (CCK-8) and flow cytometry, respectively. Cells with IL-1β and exosomes were sequenced, and differentially expressed lncRNAs (DE-lncRNAs) and miRNAs (DE-miRNAs) were identified. Thereafter, a ceRNA network (LYRM4-AS1-GRPR-miR-6515-5p) was chosen for further validation.

Results

TEM, NTA, and western blotting showed that exosomes were successfully isolated, and PKH67 staining showed that exosomes could be taken up by IL-1β-induced chondrocytes. Compared with the control group, IL-1β significantly decreased cell viability and promoted apoptosis (P < 0.05), while exosomes reversed the changes induced by IL-1β. For MMP3, AKT, and GRPR, IL-1β upregulated their expression, while exosomes downregulated their expression. For PTEN, there was no significant difference in PTEN expression between the control and IL-1β groups; however, exosomes markedly upregulated PTEN expression. By sequencing, 907 DE-lncRNAs and 25 DE-miRNAs were identified, and a ceRNA network was constructed. The dual-luciferase reporter gene indicated that LYRM4-AS1, miR-6515-5, and GRPR interacted with each other. The results of cell experiments showed that LYRM4-AS1 regulated the growth of IL-1β-induced chondrocytes by GRPR/miR-6515-5p.

Conclusion

Exosomes may alleviate OA inflammation by regulating the LYRM4-AS1/GRPR/miR-6515-5p signaling pathway.

Potential role of microRNAs as biomarkers in human glioblastoma: a mini systematic review from 2015 to 2020

Glioblastoma (GBM) is the most common, aggressive and malignant type of glioma, with poor prognosis, despite advances in medical knowledge and technology. It's known that some microRNAs (miRNAs) can be dysregulated and associated with tumors. We aim to investigate miRNAs that may have a role as potential biomarkers in human glioblastoma. A search was performed using PubMed, LILACS and SCIELO databases to find papers from 2015 to 2020, related to human in vitro and ex vivo data. From 99 articles, 10 were eligible and 13 dysregulated miRNAs were found with description of regulation, target(s), pathway(s) and mechanism(s). The miRNAs of interest were found and seem to be involved in development and progression of glioblastoma and used as target therapies. Understanding the mechanisms in which those miRNAs are involved and their role in epigenetic pathways that lead to cancer, as well as their potential in clinical application, may improve GBM clinical outcome (CRD42020182706, 07/10/2020, retrospectively registered).

Insights Into Exosomal Non-Coding RNAs Sorting Mechanism and Clinical Application

Exosomes are natural nanoscale bilayer phospholipid vesicles that can be secreted by almost all types of cells and are detected in almost all types of body fluids. Exosomes are effective mediators of cell–cell signaling communication because of their ability to carry and transfer a variety of bioactive molecules, including non-coding RNAs. Non-coding RNAs have also been found to exert strong effects on a variety of biological processes, including tumorigenesis. Many researchers have established that exosomes encapsulate bioactive non-coding RNAs that alter the biological phenotype of specific target cells in an autocrine or a paracrine manner. However, the mechanism by which the producer cells package non-coding RNAs into exosomes is not well understood. This review focuses on the current research on exosomal non-coding RNAs, including the biogenesis of exosomes, the possible mechanism of sorting non-coding RNAs, their biological functions, and their potential for clinical application in the future.

Correlation between the expression of cancer stem cell marker BMI1 and glioma prognosis

B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1) appears to be essential for promoting certain types of cancer, and its inhibition effectively reduced the stemness of cancer cells. Therefore, this study aimed to investigate the potential role of BMI1 in glioma. To this end, we first investigated BMI1 expression in brain tumors using microarray datasets in ONCOMINE, which indicated that BMI1 levels were not commonly increased in clinical brain tumors. Moreover, survival plots in PROGgeneV2 also showed that BMI1 expression was not significantly associated with reduced survival in glioma patients. Interestingly, stressful serum deprivation and anchorage independence growth conditions led to an increased BMI1 expression in glioma cells. A stress-responsive pathway, HDAC/Sp1, was further identified to regulate BMI1 expression. The HDAC inhibitor vorinostat (SAHA) prevented Sp1 binding to the BMI1 promoter, leading to a decreased expression of BMI1 and attenuating tumor growth of TMZ-resistant glioma xenografts. Importantly, we further performed survival analysis using PROGgeneV2 and found that an elevated expression of HDAC1,3/Sp1/BMI1 but not BMI1 alone showed an increased risk of death in both high- and low-grade glioma patients. Thus, HDAC-mediated Sp1 deacetylation is critical for BMI1 regulation to attenuate stress- and therapy-induced death in glioma cells, and the HDAC/Sp1 axis is more important than BMI1 and appears as a therapeutic target to prevent recurrence of malignant glioma cells persisting after primary therapy.

The Role of Extracellular Vesicles in Mediating Resistance to Anticancer Therapies

Although advances in targeted therapies have driven great progress in cancer treatment and outcomes, drug resistance remains a major obstacle to improving patient survival. Several mechanisms are involved in developing resistance to both conventional chemotherapy and molecularly targeted therapies, including drug efflux, secondary mutations, compensatory genetic alterations occurring upstream or downstream of a drug target, oncogenic bypass, drug activation and inactivation, and DNA damage repair. Extracellular vesicles (EVs) are membrane-bound lipid bilayer vesicles that are involved in cell-cell communication and regulating biological processes. EVs derived from cancer cells play critical roles in tumor progression, metastasis, and drug resistance by delivering protein and genetic material to cells of the tumor microenvironment. Understanding the biochemical and genetic mechanisms underlying drug resistance will aid in the development of new therapeutic strategies. Herein, we review the role of EVs as mediators of drug resistance in the context of cancer.

The role of extracellular vesicles in acquisition of resistance to therapy in glioblastomas

Glioblastoma (GBM) is the most aggressive primary brain tumor with a median survival of 15 months despite standard care therapy consisting of maximal surgical debulking, followed by radiation therapy with concurrent and adjuvant temozolomide treatment. The natural history of GBM is characterized by inevitable recurrence with patients dying from increasingly resistant tumor regrowth after therapy. Several mechanisms including inter- and intratumoral heterogeneity, the evolution of therapy-resistant clonal subpopulations, reacquisition of stemness in glioblastoma stem cells, multiple drug efflux mechanisms, the tumor-promoting microenvironment, metabolic adaptations, and enhanced repair of drug-induced DNA damage have been implicated in therapy failure. Extracellular vesicles (EVs) have emerged as crucial mediators in the maintenance and establishment of GBM. Multiple seminal studies have uncovered the multi-dynamic role of EVs in the acquisition of drug resistance. Mechanisms include EV-mediated cargo transfer and EVs functioning as drug efflux channels and decoys for antibody-based therapies. In this review, we discuss the various mechanisms of therapy resistance in GBM, highlighting the emerging role of EV-orchestrated drug resistance. Understanding the landscape of GBM resistance is critical in devising novel therapeutic approaches to fight this deadly disease.

CircRNA circ_0067772 aggravates the malignant progression of cutaneous squamous cell carcinoma by regulating miR-1238-3p/FOXG1 axis

BACKGROUND

Cutaneous squamous cell carcinoma (CSCC) is a severe malignancy derived from skin. Dysregulated circular RNAs (circRNAs) might play vital roles in tumor development.

OBJECTIVE

Here, we aimed to explore the function of a novel circRNA circ_0067772 in CSCC.

METHODS

Quantitative real-time PCR (qRT-PCR) or Western blot assay was performed to determine the expression of circ_0067772, microRNA (miR)-1238-3p and forkhead box protein G1 (FOXG1). Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay and colony formation assay. Transwell assay and wound healing assay were employed to examine cell metastasis. Flow cytometry was employed to monitor cell cycle and apoptosis. The target association between miR-1238-3p and circ_0067772 or FOXG1 was validated by dual-luciferase reporter assay. Moreover, role of circ_0067772 in vivo was investigated via xenograft model in nude mice.

RESULTS

Circ_0067772 and FOXG1 were upregulated, while miR-1238-3p was downregulated in CSCC tissues and cells. Circ_0067772 knockdown conferred inhibitory effects on cell proliferation, migration and invasion of CSCC cells. MiR-1238-3p served as a target of circ_0067772, whose silencing could reverse circ_0067772 knockdown-induced inhibitory impact on the malignant cellular behaviors. Circ_0067772 positively regulated FOXG1 expression by antagonizing miR-1238-3p. Additionally, miR-1238-3p could repress CSCC cell proliferation, migration and invasion by targeting FOXG1. Also, circ_0067772 knockdown hindered CSCC tumor growth in vivo.

CONCLUSION

Our study identified a novel oncogenic circRNA and the involvement of circ_0067772/miR-1238-3p/FOXG1 axis in CSCC development, providing a target for CSCC therapy.

Effects of Atrial Fibrillation-Derived Exosome Delivery of miR-107 to Human Umbilical Vein Endothelial Cells

The aim of this study was to explore the effects of atrial fibrillation (AF)-derived exosome delivery of miR-107 to human umbilical vein endothelial cells (HUVECs) and its related mechanisms. Exosomes were isolated from the plasma of patients with AF and healthy controls, followed by characterization. The expression levels of miR-320d, miR-103a-3p, and miR-107 were measured using real-time quantitative PCR (RT-qPCR). The dual-luciferase reporter gene was used to verify the downstream target of miR-107. Afterward, HUVECs were treated with AF-derived exosomes or transfected with miR-107 mimics. After cell culture, Cell Counting Kit-8, Transwell, and flow cytometry were used to determine cell viability, migration, and apoptosis and cell cycle phase. Finally, RT-qPCR was performed to examine the expression of related genes. NanoSight, transmission electron microscopy, and western blotting showed that exosomes were successfully isolated, and that AF-derived exosomes could be taken up by HUVECs. The expression of miR-107 was significantly higher in AF-derived exosomes than in normal exosomes (p < 0.05). USP14 was shown to be the direct target of miR-107. In addition, miR-107 mimics and AF-derived exosomes significantly suppressed cell viability and migration (p < 0.05) and enhanced cell apoptosis; they also increased G0/G1-phase cells and reduced S-phase cells. RT-qPCR showed that exosomal miR-107 overexpression significantly downregulated the expression of USP14 and Bcl2 (p < 0.05), whereas it markedly upregulated the expression of ERK2, FAK, and Bax (p < 0.05). AF-derived exosomes can deliver miR-107 to HUVECs, and exosomal miR-107 may regulate cell viability, migration, and apoptosis and cell cycle progression by mediating the miR-107/USP14 pathway.

Role of Tumor-Derived Extracellular Vesicles in Glioblastoma

Glioblastoma (GBM) is the most common primary central nervous system tumor and one of the most lethal cancers worldwide, with morbidity of 5.26 per 100,000 population per year. These tumors are often associated with poor prognosis and terrible quality of life. Extracellular vesicles (EVs) are membrane-bound nanoparticles secreted by cells and contain lipid, protein, DNA, mRNA, miRNA and other bioactive substances. EVs perform biological functions by binding or horizontal transfer of bioactive substances to target cell receptors. In recent years, EVs have been considered as possible targets for GBM therapy. A great many types of research demonstrated that EVs played a vital role in the GBM microenvironment, development, progression, angiogenesis, invasion, and even the diagnosis of GBM. Nevertheless, the exact molecular mechanisms and roles of EVs in these processes are unclear. It can provide the basis for GBM treatment in the future that clarifying the regulatory mechanism and related signal pathways of EVs derived from GBM and their clinical value in GBM diagnosis and treatment. In this paper, the research progress and clinical application prospects of GBM-derived EVs are reviewed and discussed.

Emerging Roles of Extracellular Vesicles in the Central Nervous System: Physiology, Pathology, and Therapeutic Perspectives

Extracellular vesicles or EVs are secreted by most, if not all, eukaryote cell types and recaptured by neighboring or distant cells. Their cargo, composed of a vast diversity of proteins, lipids, and nucleic acids, supports the EVs' inter-cellular communication. The role of EVs in many cellular processes is now well documented both in physiological and pathological conditions. In this review, we focus on the role of EVs in the central nervous system (CNS) in physiological as well as pathological conditions such as neurodegenerative diseases or brain cancers. We also discuss the future of EVs in clinical research, in particular, their value as biomarkers as well as innovative therapeutic agents. While an increasing number of studies reveal EV research as a promising field, progress in the standardization of protocols and innovation in analysis as well as in research tools is needed to make a breakthrough in our understanding of their impact in the pathophysiology of the brain.

Extracellular Vesicles: Emerging Modulators of Cancer Drug Resistance

Extracellular vesicles (EVs) have recently emerged as crucial modulators of cancer drug resistance. Indeed, it has been shown that they can directly sequester anti-tumor drugs, decreasing their effective concentration at target sites. Moreover, they facilitate the horizontal transfer of specific bioactive cargoes able to regulate proliferative, apoptotic, and stemness programs in recipient cells, potentially conferring a resistant phenotype to drug-sensitive cancer cells. Finally, EVs can mediate the communication between the tumor and both stromal and immune cells within the microenvironment, promoting treatment escape. In this context, clarifying the EV-driven resistance mechanisms might improve not only tumor diagnosis and prognosis but also therapeutic outcomes. Detailed cellular and molecular events occurring during the development of EV-mediated cancer drug resistance are described in this review article.

Pseudoprogression versus true progression in glioblastoma patients: A multiapproach literature review. Part 2 - Radiological features and metric markers

After chemoradiotherapy for glioblastoma, pseudoprogression can occur and must be distinguished from true progression to correctly manage glioblastoma treatment and follow-up. Conventional treatment response assessment is evaluated via conventional MRI (contrast-enhanced T1-weighted and T2/FLAIR), which is unreliable. The emergence of advanced MRI techniques, MR spectroscopy, and PET tracers has improved pseudoprogression diagnostic accuracy. This review presents a literature review of the different imaging techniques and potential imaging biomarkers to differentiate pseudoprogression from true progression.

Time to focus on circulating nucleic acids for diagnosis and monitoring of gliomas: A systematic review of their role as biomarkers

Gliomas are diffusely growing tumours arising from progenitors within the central nervous system. They encompass a range of different molecular types and subtypes, many of which have a well-defined profile of driver mutations, copy number changes and DNA methylation patterns. A majority of gliomas will require surgical intervention to relieve raised intracranial pressure and reduce tumour burden. A proportion of tumours, however, are located in neurologically sensitive areas and a biopsy poses a significant risk of a deficit. A majority of gliomas recur after surgery, and monitoring tumour burden of the recurrence is currently achieved by imaging. However, most imaging modalities have limitations in assessing tumour burden and infiltration into adjacent brain, and sometimes imaging is unable to discriminate between tumour recurrence and pseudo-progression. Liquid biopsies, obtained from body fluids such as cerebrospinal fluid or blood, contain circulating nucleic acids or extracellular vesicles containing tumour-derived components. The studies for this systematic review were selected according to PRISMA criteria, and suggest that the detection of circulating tumour-derived nucleic acids holds great promises as biomarker to aid diagnosis and prognostication by monitoring tumour progression, and thus can be considered a pathway towards personalized medicine.

The role of exosomal microRNAs in central nervous system diseases

MicroRNAs (miRNA), endogenous non-coding RNAs approximately 22 nucleotides long, regulate gene expression by mediating translational inhibition or mRNA degradation. Exosomes are a tool for intercellular transmission of information in which miRNA exchange plays an important role. Under pathophysiological conditions in the central nervous system (CNS), cellular transmission of exosomal miRNAs can regulate signaling pathways. Exosomal miRNAs are involved in the occurrence and development of diverse CNS diseases, such as traumatic brain injury, spinal cord injury, stroke, neurodegenerative diseases, epilepsy, and glioma. The use of exosomes as transport vehicles for certain miRNAs provides a novel therapeutic strategy for CNS diseases. Furthermore, the exosomes in body fluids change with the occurrence of diseases, indicating that subtle changes in physiological and pathological processes in vivo could be recognized by analyzing exosomes. Exosomal analysis is expected to act as a novel tool for diagnosis and prediction of neurological diseases. In this review, we present the current understanding of the implications of miRNAs in CNS diseases and summarize the role and mechanism of action of exosomal miRNA in nervous system disease models.

MicroRNA-522-3p plays an oncogenic role in glioblastoma through activating Wnt/β-catenin signaling pathway via targeting SFRP2

BACKGROUND

Increasing studies have suggested that microRNAs (miRNAs) contribute to the occurrence and development of glioblastoma. MiR-522-3p is a novel miRNA, which has been found to modulate tumorigenesis and tumor progression. However, its pathological role and functional mechanism in glioblastoma remain elusive at present.

METHOD

The miR-522-3p expression in glioblastoma and adjacent normal tissues, human fetal astrocyte HA1800, and glioblastoma cell lines was detected by reverse transcription-PCR. The proliferation, migration, and invasion were detected through Cell Counting Kit-8 (CCK8) and Transwell assay, and apoptosis was calculated through flow cytometry. The downstream target of miR-522-3p was analyzed through bioinformatics, and the correlation between miR-522-3p and secreted frizzled-related protein 2 (SFRP2) was verified through dual-luciferase reporter assay and RNA immunoprecipitation (RIP) experiment. Besides, western blot was conducted to test the level of SFRP2 and the Wnt/β-catenin pathway.

RESULTS

MiR-522-3p was overexpressed in glioblastoma tissues compared with that in normal tissues, and the inhibition of miR-522-3p reduced cell proliferation, migration, and invasion and promoted apoptosis in glioblastoma. Bioinformatics revealed that SFRP2 was an essential downstream target of miR-522-3p, and it inhibited the malignant biological behaviors induced by miR-522-3p and inactivated the Wnt/β-catenin pathway.

CONCLUSION

MiR-522-3p is an oncogene in glioblastoma by targeting SFRP2 through the Wnt/β-catenin pathway.

Potential roles and prognostic significance of exosomes in cancer drug resistance

Drug resistance is a major impediment in cancer therapy which strongly reduces the efficiency of anti-cancer drugs. Exosomes are extracellular vesicles with cup or spherical shape with a size range of 40-150 nm released by eukaryotic cells that contain genetic materials, proteins, and lipids which mediate a specific cell-to-cell communication. The potential roles of exosomes in intrinsic and acquired drug resistance have been reported in several studies. Furthermore, a line of evidence suggested that the content of exosomes released from tumor cells in biological samples may be associated with the clinical outcomes of cancer patients. In this review, we highlighted the recent studies regarding the potential roles of exosomes in tumor initiation, progression, and chemoresistance. This study suggests the possible role of exosomes for drug delivery and their contents in prognosis and resistance to chemotherapy in cancer patients.

Extracellular vesicles derived from hypoxic glioma stem-like cells confer temozolomide resistance on glioblastoma by delivering miR-30b-3p

Rationale: Glioma stem-like cells (GSCs) contribute to temozolomide (TMZ) resistance in gliomas, although the mechanisms have not been delineated. Methods: In vitro functional experiments (colony formation assay, flow cytometric analysis, TUNEL assay) were used to assess the ability of extracellular vesicles (EVs) from hypoxic GSCs to promote TMZ resistance in glioblastoma (GBM) cells. RNA sequencing and quantitative Reverse Transcription-PCR were employed to identify the functional miRNA in hypoxic EVs. Chromatin immunoprecipitation assays were performed to analyze the transcriptional regulation of miRNAs by HIF1α and STAT3. RIP and RNA pull-down assays were used to validate the hnRNPA2B1-mediated packaging of miRNA into EVs. The function of EV miR-30b-3p from hypoxic GSCs was verified by in vivo experiments and analysis of clinical samples. Results: Hypoxic GSC-derived EVs exerted a greater effect on GBM chemoresistance than those from normoxic GSCs. The miRNA profiling revealed that miR-30b-3p was significantly upregulated in the EVs from hypoxic GSCs. Further, HIF1α and STAT3 transcriptionally induced miR-30b-3p expression. RNA immunoprecipitation and RNA-pull down assays revealed that binding of miR-30b-3p with hnRNPA2B1 facilitated its transfer into EVs. EV-packaged miR-30b-3p (EV-miR-30b-3p) directly targeted RHOB, resulting in decreased apoptosis and increased proliferation in vitro and in vivo. Our results provided evidence that miR-30b-3p in CSF could be a potential biomarker predicting resistance to TMZ. Conclusion: Our findings indicated that targeting EV-miR-30b-3p could provide a potential treatment strategy for GBM.

Exosomal circRNAs: Sorting Mechanisms, Roles and Clinical Applications in Tumors

Exosomes are a group of nano-sized membrane vesicles and are important mediators of intercellular communication, particularly in tumor microenvironment. Recently, researchers have found that circular RNAs (circRNAs), with the great research significance, are enriched and stable in exosomes. In this review, we summarize the research significance of exosomal circRNAs, sorting mechanisms and their functioning mechanisms in tumor progression. Their clinical applications as clinical tumor biomarkers and as therapeutic targets in inhibiting tumor metastasis, anti-cancer immunity response and drug resistance have been widely discussed.