Long noncoding RNA CASC2 predicts the prognosis of glioma patients and functions as a suppressor for gliomas by suppressing Wnt/β-catenin signaling pathway

Innovative perspectives on glioblastoma: the emerging role of long non-coding RNAs

Glioblastoma (GBM) is a highly aggressive and treatment-resistant brain tumor. Recent advancements have highlighted the crucial role of long noncoding RNAs (lncRNAs) in GBM's molecular biology. Unlike protein-coding RNAs, lncRNAs regulate gene expression through transcription, post-transcriptional modifications, and chromatin remodeling. Some lncRNAs, like HOTAIR, CCAT2, CRNDE, and MALAT1, promote GBM development by affecting tumor suppressors and various signaling pathways like PI3K/Akt, mTOR, EGFR, NF-κB, and Wnt/β-catenin. Conversely, certain lncRNAs such as TUG1, MEG3, and GAS8-AS1 act as tumor suppressors and are associated with better prognosis. The study presented in the manuscript aims to explore the involvement of lncRNAs in GBM, focusing on their roles in tumor progression, proliferation, invasion, and potential implications for early detection and immunotherapy. The research seeks to elucidate the mechanisms by which specific lncRNAs influence GBM characteristics and highlight their potential as therapeutic targets or biomarkers in managing this aggressive form of brain cancer.

Immunological processes of enhancers and suppressors of long non-coding RNAs associated with brain tumors and inflammation

Immunological processes, such as inflammation, can both cause tumor suppression and cancer progression. Moreover, deregulated levels of long non-coding RNA (lncRNA) expression in the brain may cause inflammation and lead to the growth of tumors. Like other biological processes, the immune system's role in cancer is complicated, varies, and can help or hurt the cancer's maintenance. According to research, inflammation and brain cancer are correlated via several signaling pathways. A variety of lncRNAs have recently been revealed to influence cancer by modulating inflammatory pathways. As a result, lncRNAs have the potential to influence carcinogenesis, tumor formation, or tumor suppression via an increase or decrease in inflammation functions. Although the study and targeting of lncRNAs have made great progress in the treatment of cancer, there are definitely limitations and challenges. Using new technologies like nanocarriers and cell-penetrating peptides (CPPs) to target treatments without hurting healthy body tissues has shown to be very effective. In this review article, we have collected significantly related lncRNAs and their inhibitory or stimulating roles in inflammation and brain cancer for the first time. However, there are limitations, such as side effects and damage to normal tissues. With the advancement of new targeting technologies, these lncRNAs may be candidates for the specific targeting therapy of brain cancers by limiting inflammation or stimulating the immune system against them in the future.

lncRNA Biomarkers of Glioblastoma Multiforme

Long noncoding RNAs (lncRNAs) are RNA molecules of 200 nucleotides or more in length that are not translated into proteins. Their expression is tissue-specific, with the vast majority involved in the regulation of cellular processes and functions. Many human diseases, including cancer, have been shown to be associated with deregulated lncRNAs, rendering them potential therapeutic targets and biomarkers for differential diagnosis. The expression of lncRNAs in the nervous system varies in different cell types, implicated in mechanisms of neurons and glia, with effects on the development and functioning of the brain. Reports have also shown a link between changes in lncRNA molecules and the etiopathogenesis of brain neoplasia, including glioblastoma multiforme (GBM). GBM is an aggressive variant of brain cancer with an unfavourable prognosis and a median survival of 14-16 months. It is considered a brain-specific disease with the highly invasive malignant cells spreading throughout the neural tissue, impeding the complete resection, and leading to post-surgery recurrences, which are the prime cause of mortality. The early diagnosis of GBM could improve the treatment and extend survival, with the lncRNA profiling of biological fluids promising the detection of neoplastic changes at their initial stages and more effective therapeutic interventions. This review presents a systematic overview of GBM-associated deregulation of lncRNAs with a focus on lncRNA fingerprints in patients' blood.

Engineered smart materials for RNA based molecular therapy to treat Glioblastoma

Glioblastoma (GBM) is an aggressive malignancy of the central nervous system (CNS) that remains incurable despite the multitude of improvements in cancer therapeutics. The conventional chemo and radiotherapy post-surgery have only been able to improve the prognosis slightly; however, the development of resistance and/or tumor recurrence is almost inevitable. There is a pressing need for adjuvant molecular therapies that can successfully and efficiently block tumor progression. During the last few decades, non-coding RNAs (ncRNAs) have emerged as key players in regulating various hallmarks of cancer including that of GBM. The levels of many ncRNAs are dysregulated in cancer, and ectopic modulation of their levels by delivering antagonists or overexpression constructs could serve as an attractive option for cancer therapy. The therapeutic potential of several types of ncRNAs, including miRNAs, lncRNAs, and circRNAs, has been validated in both in vitro and in vivo models of GBM. However, the delivery of these RNA-based therapeutics is highly challenging, especially to the tumors of the brain as the blood-brain barrier (BBB) poses as a major obstacle, among others. Also, since RNA is extremely fragile in nature, careful considerations must be met while designing a delivery agent. In this review we have shed light on how ncRNA therapy can overcome the limitations of its predecessor conventional therapy with an emphasis on smart nanomaterials that can aide in the safe and targeted delivery of nucleic acids to treat GBM. Additionally, critical gaps that currently exist for successful transition from viral to non-viral vector delivery systems have been identified. Finally, we have provided a perspective on the future directions, potential pathways, and target areas for achieving rapid clinical translation of, RNA-based macromolecular therapy to advance the effective treatment of GBM and other related diseases.

Expression of lncRNAs in glioma: A lighthouse for patients with glioma

Glioma is the most common malignant tumour in the central nervous system, accounting for approximately 30 % of the primary tumours of this system. The World Health Organization grades for glioma include: Grade I (pilocytic astrocytoma), Grade II (astrocytoma, oligodastoma, etc.), Grade III (anaplastic astrocytoma, anaplastic oligodastoma, etc.) and Grade IV (glioblastoma). With grade increases, the proliferation, invasion and other malignant biological properties of the glioma are enhanced, and the treatment results are less satisfactory. The overall survival of patients with glioblastoma is less than 15 months. Recent research has focused on the roles of long non-coding RNAs, previously regarded as "transcriptional noise", in diseases, leading to a new understanding of these roles. Therefore, we conducted this review to explore the progress of research regarding the expression and mechanism of long non-coding RNAs in glioma.

Non-coding RNAs as Key Regulators of the Notch Signaling Pathway in Glioblastoma: Diagnostic, Prognostic, and Therapeutic Targets

Glioblastoma multiforme (GBM) is a highly invasive brain malignancy originating from astrocytes, accounting for approximately 30% of central nervous system malignancies. Despite advancements in therapeutic strategies including surgery, chemotherapy, and radiopharmaceutical drugs, the prognosis for GBM patients remains dismal. The aggressive nature of GBM necessitates the identification of molecular targets and the exploration of effective treatments to inhibit its proliferation. The Notch signaling pathway, which plays a critical role in cellular homeostasis, becomes deregulated in GBM, leading to increased expression of pathway target genes such as MYC, Hes1, and Hey1, thereby promoting cellular proliferation and differentiation. Recent research has highlighted the regulatory role of non-coding RNAs (ncRNAs) in modulating Notch signaling by targeting critical mRNA expression at the post-transcriptional or transcriptional levels. Specifically, various types of ncRNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), have been shown to control multiple target genes and significantly contribute to the carcinogenesis of GBM. Furthermore, these ncRNAs hold promise as prognostic and predictive markers for GBM. This review aims to summarize the latest studies investigating the regulatory effects of ncRNAs on the Notch signaling pathway in GBM.

LncRNA CASC2 Inhibits Progression of Glioblastoma by Regulating the Expression of AKT in T98G Cell Line, Treated by TMZ and Thiosemicarbazone Complex

BACKGROUND

The aim of this study was to evaluate the expression alterations of CACS2 and its target gene, AKT, in T98G cell line treated with Temozolomide and Thiosemicarbazone complex (Ni, Cu) and to compare the results with each other.

METHODS

Temozolomide and Thiosemicarbazone complexes were prepared in different concentrations. Cell culturing of T98G cell line was carried out and was classified into 3 groups based on the incubation time (24, 48, and 72h) with utilized agents, after RNA extraction the expression level of CACS2 and AKT genes were evaluated by Real-time PCR. Ultimately, the results were analyzed by Rest software.

RESULTS

CASC2 expression under Temozolomide treatment at different concentrations (100, 150, 200, and 250 µM) and different time periods (24, 48, and 72h) was increased. Moreover, its expression was significantly upregulated after treating with Ni at the concentrations of 100.5 and 104 µM after 24h. Furthermore, its expression was augmented after 72 h Cu treatment at the concentrations of 15, 16, 17, and 18 µM. In addition, AKT expression after Temozolomide and Thiosemicarbazone complex treatment was significantly decreased (P <0.001). The results showed that the expression alterations of CASC2 and its target gene, AKT, after treatment with Temozolomide and Thiosemicarbazone are highly depended on incubation time and concentration.

CONCLUSION

In a conclusion, the studied agents at different concentrations and times showed a high potential to control the expression of the studied lncRNA and gene in glioblastoma cells.

LINC01426 aggravates the malignant progression of glioma through miR-661/Mdm2 axis

BACKGROUND

Long intergenic non-protein coding RNA 1426 (LINC01426) is up-regulated in glioma and functions as a tumor promoter. However, the role of LINC01426 in glioma required further exploration. Therefore, this article mainly studied the role and possible mechanism of LINC01426 in glioma.

METHODS

The area under the receiver operating characteristic curve was used to determine the diagnostic value of LINC01426. The effect of LINC01426 on tumor growth was analyzed by tumorigenesis assay and immunohistochemical analysis. Bioinformatics analysis, dual-luciferase assay, RNA pull-down, Pearson test, and real-time quantitative PCR (RT-qPCR) were applied to verify the relationship between target genes. The expressions and effects of LINC01426, miR-661 and MDM2 proto-oncogene (Mdm2) in glioma were examined by bioinformatics analysis combined with molecular and functional experiments (RT-qRCR, 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide, clone formation, BrdU, flow cytometry). The expressions of proliferation and apoptosis-related proteins were determined by Western blot.

RESULTS

LINC01426, which was high-expressed in glioma and was related to poor prognosis, could be used as a diagnostic marker for glioma. SiLINC01426 inhibited the malignant phenotype of glioma cells in vitro and attenuated tumor growth and PCNA expression in vivo, while the effects of LINC01426 were the opposite. LINC01426 targeted and inversely correlated with miR-661, which was low-expressed in glioma. MiR-661 inhibitor evidently overturned the effect of siLINC01426 on biological functions, proliferation, and apoptosis-related proteins of glioma cells. Mdm2 bound to miR-661. Moreover, siMdm2 reversed the effects of miR-661 inhibitor on the biological characteristics and Mdm2/p53/p21 expression of glioma cells.

CONCLUSION

LINC01426 aggravated the malignant progression of glioma through miR-661/Mdm2 axis.

Non-coding RNAs and glioblastoma: Insight into their roles in metastasis

Glioma, also known as glioblastoma multiforme (GBM), is the most prevalent and most lethal primary brain tumor in adults. Gliomas are highly invasive tumors with the highest death rate among all primary brain malignancies. Metastasis occurs as the tumor cells spread from the site of origin to another site in the brain. Metastasis is a multifactorial process, which depends on alterations in metabolism, genetic mutations, and the cancer microenvironment. During recent years, the scientific study of non-coding RNAs (ncRNAs) has led to new insight into the molecular mechanisms involved in glioma. Many studies have reported that ncRNAs play major roles in many biological procedures connected with the development and progression of glioma. Long ncRNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are all types of ncRNAs, which are commonly dysregulated in GBM. Dysregulation of ncRNAs can facilitate the invasion and metastasis of glioma. The present review highlights some ncRNAs that have been associated with metastasis in GBM. miRNAs, circRNAs, and lncRNAs are discussed in detail with respect to their relevant signaling pathways involved in metastasis.

Circular RNA circBFAR promotes glioblastoma progression by regulating a miR-548b/FoxM1 axis

Glioblastoma multiforme (GBM) is the most common and aggressive type of tumor of the primary nervous system. Treatment options for GBM include surgery, chemotherapy, and radiation therapy; however, the clinical outcomes are poor, with a high rate of recurrence. An increasing number of studies have shown that circular RNAs (circRNAs) serve important roles in several types of cancer. Gene Expression Omnibus (GEO) database was utilized to identify the differentially expressed circRNAs and their biological functions. Then, we detected the circular RNA bifunctional apoptosis regulator (circBFAR) was significantly increased in three GEO datasets. However, the role of circBFAR has not been reported in GBM. In this study, the expression of circBFAR was significantly increased both in GBM tissues or cell lines and was negatively correlated with overall survival in patients with GBM. Knockdown of circBFAR inhibited proliferation and invasion both in vitro and in vivo. Increased expression of circBFAR resulted in a reduction of miR-548b expression in glioma cells. A luciferase reporter and RIP assay indicated that miR-548b was a direct target of circBFAR, and miR-548b may negatively regulate the expression of FoxM1. Rescue experiments showed that overexpression of FoxM1 could counter the effect of circBFAR silencing on the proliferation and invasion of glioma cell lines. Moreover, we identified that circBFAR regulates FoxM1 by interacting with miR-548b in glioma cells. In conclusion, the present study demonstrated that a circBFAR/miR-548b/FoxM1 axis regulates the development of GBM and highlights potentially novel therapeutic targets for the treatment of GBM.

Metastasis associated long noncoding RNAs in glioblastoma: Biomarkers and therapeutic targets

Glioblastoma (GBM) is the most aggressive, malignant, and therapeutically challenging Grade IV tumor of the brain. Although the possibility of distant metastasis is extremely rare, GBM is known to cause intracranial metastasis forming aggressive secondary lesions resulting in a dismal prognosis. Metastasis also plays an important role in tumor dissemination and recurrence making GBM largely incurable. Recent studies have indicated the importance of long noncoding RNAs (lncRNAs) in GBM metastasis. lncRNAs are a class of regulatory noncoding RNAs (>200 nt) that interact with DNA, RNA, and proteins to regulate various biological processes. This is the first comprehensive review summarizing the lncRNAs associated with GBM metastasis and the underlying molecular mechanism involved in migration/invasion. We also highlight the complex network of lncRNA/miRNA/protein that collaborate/compete to regulate metastasis-associated genes. Many of these lncRNAs also show attractive potential as diagnostic/prognostic biomarkers. Finally, we discuss various therapeutic strategies and potential applications of lncRNAs as therapeutic targets for the treatment of GBM.

The EIF4A3/CASC2/RORA Feedback Loop Regulates the Aggressive Phenotype in Glioblastomas

Glioblastoma (GBM) is a common and refractory subtype of high-grade glioma with a poor prognosis. The epithelial-mesenchymal transition (EMT) is an important cause of enhanced glioblastoma invasiveness and tumor recurrence. Our previous study found that retinoic acid receptor-related orphan receptor A (RORA) is a nuclear receptor and plays an important role in inhibiting proliferation and tumorigenesis of glioma. We further confirmed RORA was downregulated in GBM. Thus, we determined whether RORA was involved in the migration, invasion, and EMT of GBM. Human GBM cell lines, U87 and T98G, and patient-derived glioma stem cells (GSCs), GSC2C and GSC4D, were used for in vitro and in vivo experiments. The expressions of RORA, CASC2, and EIF4A3 in GBM cells and GSCs were detected by RT-qPCR and western blotting. The biological effects of RORA, CASC2, and EIF4A3 on GBM migration, invasion, and EMT were evaluated using the migration assay, transwell assay, immunofluorescence staining, and xenograft experiments. We found that RORA inhibited the migration, invasion, and EMT of GBM. CASC2 could bind to, maintain the stability, and promote the nuclear translocation of RORA protein. EIF4A3 could downregulate CASC2 expression via inducing its cleavage, while RORA transcriptionally inhibited EIF4A3 expression, which formed a feedback loop among EIF4A3/CASC2/RORA. Moreover, gene set enrichment analysis (GSEA) and in vitro and in vivo experiments showed RORA inhibited the aggressiveness of GBM by negatively regulating the TGF-β1/Smad signaling pathway. Therefore, The EIF4A3/CASC2/RORA feedback loop regulated TGF-β1/Smad signaling pathway might become a promising therapeutic strategy for GBM treatment.

Long non-coding RNAs in brain tumors: roles and potential as therapeutic targets

Brain tumors are associated with adverse outcomes despite improvements in radiation therapy, chemotherapy, and photodynamic therapy. However, treatment approaches are evolving, and new biological phenomena are being explored to identify the appropriate treatment of brain tumors. Long non-coding RNAs (lncRNAs), a type of non-coding RNA longer than 200 nucleotides, regulate gene expression at the transcriptional, post-transcriptional, and epigenetic levels and are involved in a variety of biological functions. Recent studies on lncRNAs have revealed their aberrant expression in various cancers, with distinct expression patterns associated with their instrumental roles in cancer. Abnormal expression of lncRNAs has also been identified in brain tumors. Here, we review the potential roles of lncRNAs and their biological functions in the context of brain tumors. We also summarize the current understanding of the molecular mechanisms and signaling pathways related to lncRNAs that may guide clinical trials for brain tumor therapy.

Potential of long non-coding RNAs as a therapeutic target and molecular markers in glioblastoma pathogenesis

Glioblastoma (GB) is by far the most hostile type of malignant tumor that primarily affects the brain and spine, derived from star-shaped glial cells that are astrocytes and oligodendrocytes. Despite of significant efforts in recent years in glioblastoma research, the clinical efficacy of existing medical intervention is still limited and very few potential diagnostic markers are available. Long non-coding RNAs (lncRNAs) that lacks protein-coding capabilities were previously thought to be "junk sequences" in mammalian genomes are quite indispensible epigenetic regulators that can positively or negatively regulate gene expression and nuclear architecture, with significant roles in the initiation and development of tumors. Nevertheless, the precise mechanism of these distortedly expressed lncRNAs in glioblastoma pathogenesis is not yet fully understood. Since the advent of high-throughput sequencing technologies, more and more research have elucidated that lncRNAs are one of the most promising prognostic biomarkers and therapeutic targets for glioblastoma. In this paper, I briefly outlined the existing findings of lncRNAs. And also summarizes the profiles of different lncRNAs that have been broadly classified in glioblastoma research, with emphasis on both their prognostic and therapeutic values.

Long non-coding RNAs in brain tumors

Long non-coding RNAs (lncRNAs) have been found to be central players in the epigenetic, transcriptional and post-transcriptional regulation of gene expression. There is an accumulation of evidence on newly discovered lncRNAs, their molecular interactions and their roles in the development and progression of human brain tumors. LncRNAs can have either tumor suppressive or oncogenic functions in different brain cancers, making them attractive therapeutic targets and biomarkers for personalized therapy and precision diagnostics. Here, we summarize the current state of knowledge of the lncRNAs that have been implicated in brain cancer pathogenesis, particularly in gliomas and medulloblastomas. We discuss their epigenetic regulation as well as the prospects of using lncRNAs as diagnostic biomarkers and therapeutic targets in patients with brain tumors.

Inhibition of lncRNA LINC00461/miR-216a/aquaporin 4 pathway suppresses cell proliferation, migration, invasion, and chemoresistance in glioma

Long noncoding RNA (lncRNA) LINC00461 (LINC00461) is reported to be related to glioma progression. However, the mechanism of LINC00461 in glioma remains unclear. Expression of LINC00461, miRNA (miR)-216a, and aquaporin 4 (AQP4) was detected using real-time quantitative PCR (RT-qPCR) and western blotting. Proliferation, temozolomide (TMZ) resistance, migration, and invasion were assessed by MTT, colony formation, and transwell assays, respectively. The target binding among miR-216a, LINC00461, and AQP4 was confirmed by the luciferase reporter assay. The tumor growth was monitored in the xenograft experiment. LINC00461 was upregulated, and miR-216a was downregulated in glioma tissues and cells, and LINC00461 upregulation was correlated with large tumor size, higher WHO grade and recurrence, and poor overall survival. LINC00461 knockdown suppressed cell viability, abilities of cell cloning and migration and invasion, and TMZ resistance in glioma. Mechanically, LINC00461 was confirmed to sponge miR-216a to affect AQP4 expression. Rescue assays verified that miR-216a downregulation or AQP4 upregulation abrogated the inhibitory effect of LINC00461 knockdown on cell proliferation, migration, invasion, and TMZ resistance in vitro. Moreover, LINC00461 downregulation blocked the glioma tumor growth in vivo. In conclusion, LINC00461 knockdown inhibits glioma cell proliferation, migration, invasion, and TMZ resistance through miR-216a/AQP4 axis, suggesting LINC00461 as an oncogene in glioma progression.

Coding of Glioblastoma Progression and Therapy Resistance through Long Noncoding RNAs

Glioblastoma is the most aggressive and lethal primary brain malignancy, with an average patient survival from diagnosis of 14 months. Glioblastoma also usually progresses as a more invasive phenotype after initial treatment. A major step forward in our understanding of the nature of glioblastoma was achieved with large-scale expression analysis. However, due to genomic complexity and heterogeneity, transcriptomics alone is not enough to define the glioblastoma "fingerprint", so epigenetic mechanisms are being examined, including the noncoding genome. On the basis of their tissue specificity, long noncoding RNAs (lncRNAs) are being explored as new diagnostic and therapeutic targets. In addition, growing evidence indicates that lncRNAs have various roles in resistance to glioblastoma therapies (e.g., MALAT1, H19) and in glioblastoma progression (e.g., CRNDE, HOTAIRM1, ASLNC22381, ASLNC20819). Investigations have also focused on the prognostic value of lncRNAs, as well as the definition of the molecular signatures of glioma, to provide more precise tumor classification. This review discusses the potential that lncRNAs hold for the development of novel diagnostic and, hopefully, therapeutic targets that can contribute to prolonged survival and improved quality of life for patients with glioblastoma.

Long Non-Coding RNAs As Epigenetic Regulators in Cancer

Long noncoding RNAs (lncRNAs) constitute large portions of the mammalian transcriptome which appeared as a fundamental player, regulating various cellular mechanisms. LncRNAs do not encode proteins, have mRNA-like transcripts and frequently processed similar to the mRNAs. Many investigations have determined that lncRNAs interact with DNA, RNA molecules or proteins and play a significant regulatory function in several biological processes, such as genomic imprinting, epigenetic regulation, cell cycle regulation, apoptosis, and differentiation. LncRNAs can modulate gene expression on three levels: chromatin remodeling, transcription, and post-transcriptional processing. The majority of the identified lncRNAs seem to be transcribed by the RNA polymerase II. Recent evidence has illustrated that dysregulation of lncRNAs can lead to many human diseases, in particular, cancer. The aberrant expression of lncRNAs in malignancies contributes to the dysregulation of proliferation and differentiation process. Consequently, lncRNAs can be useful to the diagnosis, treatment, and prognosis, and have been characterized as potential cancer markers as well. In this review, we highlighted the role and molecular mechanisms of lncRNAs and their correlation with some of the cancers.

Current advances of long non-coding RNAs mediated by wnt signaling in glioma

Glioma is the most common and aggressive brain tumor in the central nervous system (CNS), in which Wnt signaling pathway has been verified to play a pivotal role in regulating the initiation and progression. Currently, numerous studies have indicated that long non-coding RNAs (lncRNAs) have critical functions across biological processes including cell proliferation, colony formation, migration, invasion and apoptosis via Wnt signaling pathway in glioma. This review depicts canonical and non-canonical Wnt/β-catenin signaling pathway properties and relative processing mechanisms in gliomas, and summarizes the function and regulation of lncRNAs mediated by Wnt signaling pathway in the development and progression of glioma. Ultimately, we hope to seek out promising biomarkers and reliable therapeutic targets for glioma.

The role of long non-coding RNA CASC2 in the carcinogenesis process

The lncRNA cancer susceptibility candidate 2 (CASC2) has been initially discovered in a genomic area on 10q26 that is commonly lost in human endometrial cancer. Subsequent assessments revealed its down-regulation in almost all kinds of cancer including glioma, breast cancer, colorectal cancer, lung cancer, ovarian cancer and hepatocellular carcinoma. Yet, it has been shown to be up-regulated in astrocytoma and in paclitaxel (PTX) resistant breast cancer tissues. In vitro studies have shown the role of this lncRNA in suppression of cell proliferation and induction of apoptosis. Animal studies have shown that over-expression of CASC2 suppresses tumorigenesis of human cancer cells in xenograft models. Diagnostic power of CASC2 levels has been evaluated in a number of human cancers and the best parameters have been demonstrated in pituitary adenomas and oral squamous cell carcinoma. Taken together, the main body of evidence show a tumor suppressor role of CASC2 and indicate up-regulation of this lncRNA as a putative therapeutic modality for human cancers. In this review, we summarize the data regarding expression pattern, function and diagnostic role of CASC2 in human cancer based on the results of cell line studies, animal investigations and human studies.

Emerging Roles and Potential Applications of Non-Coding RNAs in Glioblastoma

Non-coding RNAs (ncRNAs) comprise a diversity of RNA species, which do not have the potential to encode proteins. Non-coding RNAs include two classes of RNAs, namely: short regulatory ncRNAs and long non-coding RNAs (lncRNAs). The short regulatory RNAs, containing up to 200 nucleotides, include small RNAs, such as microRNAs (miRNA), short interfering RNAs (siRNAs), piwi-interacting RNAs (piRNAs), and small nucleolar RNAs (snoRNAs). The lncRNAs include long antisense RNAs and long intergenic RNAs (lincRNAs). Non-coding RNAs have been implicated as master regulators of several biological processes, their expression being strictly regulated under physiological conditions. In recent years, particularly in the last decade, substantial effort has been made to investigate the function of ncRNAs in several human diseases, including cancer. Glioblastoma is the most common and aggressive type of brain cancer in adults, with deregulated expression of small and long ncRNAs having been implicated in onset, progression, invasiveness, and recurrence of this tumor. The aim of this review is to guide the reader through important aspects of miRNA and lncRNA biology, focusing on the molecular mechanism associated with the progression of this highly malignant cancer type.

Tumor mutational burden predicts survival in patients with low-grade gliomas expressing mutated IDH1

Background

Gliomas are the most common primary brain tumors. High-Grade Gliomas have a median survival (MS) of 18 months, while Low-Grade Gliomas (LGGs) have an MS of approximately 7.3 years. Seventy-six percent of patients with LGG express mutated isocitrate dehydrogenase (mIDH) enzyme. Survival of these patients ranges from 1 to 15 years, and tumor mutational burden ranges from 0.28 to 3.85 somatic mutations/megabase per tumor. We tested the hypothesis that the tumor mutational burden would predict the survival of patients with tumors bearing mIDH.

Methods

We analyzed the effect of tumor mutational burden on patients' survival using clinical and genomic data of 1199 glioma patients from The Cancer Genome Atlas and validated our results using the Glioma Longitudinal AnalySiS consortium.

Results

High tumor mutational burden negatively correlates with the survival of patients with LGG harboring mIDH (P = .005). This effect was significant for both Oligodendroglioma (LGG-mIDH-O; MS = 2379 vs 4459 days in high vs low, respectively; P = .005) and Astrocytoma (LGG-mIDH-A; MS = 2286 vs 4412 days in high vs low respectively; P = .005). There was no differential representation of frequently mutated genes (eg, TP53, ATRX, CIC, and FUBP) in either group. Gene set enrichment analysis revealed an enrichment in Gene Ontologies related to cell cycle, DNA-damage response in high versus low tumor mutational burden. Finally, we identified 6 gene sets that predict survival for LGG-mIDH-A and LGG-mIDH-O.

Conclusions

we demonstrate that tumor mutational burden is a powerful, robust, and clinically relevant prognostic factor of MS in mIDH patients.

Meg3 Induces EMT and Invasion of Glioma Cells via Autophagy

Background

Glioma is one of the most common malignant tumors. Glioblastoma (grade IV) is considered the most malignant form of human brain tumors. Maternal expression gene 3 (Meg3) encodes a non-coding RNA (ncRNA) that plays an important role in the development and progression of cancer. However, the role of Meg3 in glioma cells remains largely unclear.

Methods

Reverse transcription-quantitative (RT-q) PCR was conducted to evaluate the mRNA expression related to cell autophagy and EMT while protein expression was detected by Western blotting. Staining of acidic vacuoles and immunofluorescence staining were used to detect autophagy. The ability of cells to migrate and invade was detected by Transwell migration and invasion assays.

Results

In the present study, it was found that the overexpression of Meg3 induced EMT, migration and invasion of glioma cells, whereas Meg3 overexpression induced autophagy of glioma cells. More importantly, the inhibition of autophagy impaired the EMT of glioma cells. In addition, Meg3-induced EMT, migration and invasion could be partially reversed by autophagy inhibitors, chloroquine (CQ) and Lys05, in glioma cells.

Conclusion

All data suggest that Meg3 induces EMT and invasion of glioma cells via autophagy. Overall, the findings of the present study demonstrate the importance of Meg3 in the molecular etiology of glioma, which also indicate its potential applications in the treatment of glioma.

The Long Non-Coding RNA CASC2 Suppresses Cell Viability, Migration, and Invasion in Hepatocellular Carcinoma Cells by Directly Downregulating miR-183

PURPOSE

Hepatocellular carcinoma (HCC) is the most common malignant tumor of liver cells. Researchers have reported that cancer susceptibility candidate 2 (CASC2), a long non-coding RNA, is down-regulated in various cancers, including HCC. Our study aimed to investigate the molecular mechanism(s) of CASC2 in HCC.

MATERIALS AND METHODS

Real-time quantitative PCR (RT-qPCR) was used to analyze the expression of CASC2 and miR-183 in HCC tissues and cells. The viability of HCC SMMC-7721 and Huh-7 cells was detected through MTT assay. Colony formation assay was performed to assess the colony formation ability of HCC cells. The migration and invasion abilities of HCC cells were evaluated by Transwell assay. Western blot was conducted to examine levels of key Wnt/β-catenin signaling pathway factors, C-myc, cyclinD, survivin, and β-catenin. The interaction between CASC2 and miR-183 was affirmed by bioinformatics analysis and luciferase reporter assay.

RESULTS

CASC2 was down-regulated in HCC tissues and cell lines, while miR-183 was up-regulated. The expression of miR-183 was negatively correlated with CASC2 expression in HCC tissues. Overexpression of CASC2 inhibited cell viability, colony formation, migration, and invasion in HCC cells, as well as Wnt/β-catenin signaling pathway activity. miR-183 was a downstream target of CASC2 and negatively regulated by CASC2. Introduction of miR-183 rescued CASC2-induced suppressive effects on HCC cell viability, colony formation, migration, and invasion and Wnt/β-catenin signaling.

CONCLUSION

CASC2 inhibited cell viability and the colony formation, migration, and invasion abilities of HCC cells by directly downregulating miR-183 through inactivation of the Wnt/β-catenin signaling pathway.

Long non-coding RNAs are emerging targets of phytochemicals for cancer and other chronic diseases

The long non-coding RNAs (lncRNAs) are the crucial regulators of human chronic diseases. Therefore, approaches such as antisense oligonucleotides, RNAi technology, and small molecule inhibitors have been used for the therapeutic targeting of lncRNAs. During the last decade, phytochemicals and nutraceuticals have been explored for their potential against lncRNAs. The common lncRNAs known to be modulated by phytochemicals include ROR, PVT1, HOTAIR, MALAT1, H19, MEG3, PCAT29, PANDAR, NEAT1, and GAS5. The phytochemicals such as curcumin, resveratrol, sulforaphane, berberine, EGCG, and gambogic acid have been examined against lncRNAs. In some cases, formulation of phytochemicals has also been used. The disease models where phytochemicals have been demonstrated to modulate lncRNAs expression include cancer, rheumatoid arthritis, osteoarthritis, and nonalcoholic fatty liver disease. The regulation of lncRNAs by phytochemicals can affect multi-steps of tumor development. When administered in combination with the conventional drugs, phytochemicals can also produce synergistic effects on lncRNAs leading to the sensitization of cancer cells. Phytochemicals target lncRNAs either directly or indirectly by affecting a wide variety of upstream molecules. However, the potential of phytochemicals against lncRNAs has been demonstrated mostly by preclinical studies in cancer models. How the modulation of lncRNAs by phytochemicals produce therapeutic effects on cancer and other chronic diseases is discussed in this review.

Knockdown of long non-coding RNA SNHG5 inhibits malignant cellular phenotypes of glioma via Wnt/CTNNB1 signaling pathway

Objective: Human brain glioma is the most malignant primary intracranial tumor, which has poor prognosis and high mortality. Long noncoding RNAs are considered to take part in cellular phenotypes and are emerging as diagnostic and prognostic biomarkers of glioma. This study will research the effects of Small Nucleolar RNA Host Gene 5 (SNHG5) gene on malignant cellular phenotypes in glioma and explore the possible mechanisms. Materials and Methods: The expression level of SNHG5 was examined using quantitative Real-time PCR in glioma tissues and cell lines. Loss-of-function experiments of SNHG5 together with Enhanced Cell Counting Kit-8, flow cytometry and cell invasion assay were used to investigate the effects of SNHG5 on malignant cellular phenotypes of glioma cells. Finally, luciferase assay and western blotting were applied to determine the activity of WNT/CTNNB1 signaling pathway. Results: SNHG5 gene was high-expressed in glioma tissues and cell lines. Knockdown of SNHG5 gene depressed cell proliferation and invasiveness as well as promoted the apoptosis of U251 and U87 cells. In addition, online database analysis showed SNHG5 was closely related to Wnt/CTNNB1 signaling pathway. Knockdown of SNHG5 inactivated Wnt/CTNNB1 signaling pathway, and the activating of Wnt/CTNNB1 signaling pathway partly restored the influences of SNHG5 knockdown on malignant cellular phenotypes of U251 and U87 cells. Conclusion: SNHG5 gene was high-expressed in glioma, knockdown of SNHG5 inhibits malignant cellular phenotypes of glioma via Wnt/CTNNB1 signaling pathway.

Non-Coding RNAs in Glioma

Glioma is the most aggressive brain tumor of the central nervous system. The ability of glioma cells to migrate, rapidly diffuse and invade normal adjacent tissue, their sustained proliferation, and heterogeneity contribute to an overall survival of approximately 15 months for most patients with high grade glioma. Numerous studies indicate that non-coding RNA species have critical functions across biological processes that regulate glioma initiation and progression. Recently, new data emerged, which shows that the cross-regulation between long non-coding RNAs and small non-coding RNAs contribute to phenotypic diversity of glioblastoma subclasses. In this paper, we review data of long non-coding RNA expression, which was evaluated in human glioma tissue samples during a five-year period. Thus, this review summarizes the following: (I) the role of non-coding RNAs in glioblastoma pathogenesis, (II) the potential application of non-coding RNA species in glioma-grading, (III) crosstalk between lncRNAs and miRNAs (IV) future perspectives of non-coding RNAs as biomarkers for glioma.

The value of long noncoding RNA CASC2 as a biomarker of prognosis in carcinomas: a meta-analysis

Lnc RNA Cancer Susceptibility Candidate 2(CASC2) has been shown to be aberrantly expressed in multiple types of cancer and might serve as a prognosis biomarker. The present meta-analysis was conducted to investigate whether the expression of CASC2 was associated with prognosis or clinicopathological features in correlative cancers. A total of 11 studies with 765 cancer patients were included by searching the electronic databases, the results found a significant association between high expression of CASC2 and longer OS in cancer patients (HR=0.43, 95% CI: 0.33-0.55, P =0.000).In addition, a significant correlation was observed between high level of CASC2 and earlier TNM stage(OR = 0.30, 95% CI =0.21-0.43, P < 0.001), smaller tumor size(OR = 0.28, 95% CI =0.12-0.66, P =0.004), better tumor differentiation(OR = 0.42, 95% CI =0.27-0.66, P =0.0002). In conclusion, CASC2 can serve as a novel marker predicting the prognosis and clinicopathological features in various cancers.

CASC2: An emerging tumour-suppressing long noncoding RNA in human cancers and melanoma

Deregulation of long noncoding RNAs (lncRNAs) has been implicated in tumourigenesis. Cancer Susceptibility Candidate 2 (CASC2) is a lncRNA downregulated in multiple cancer types, including endometrial, lung, gastric and colorectal cancers. CASC2 functions as a tumour-suppressive lncRNA though multiple mechanisms, such as sequestration of oncogenic microRNAs and repression of Wnt/β-catenin signalling. Pertinent to clinical practice, the use of CASC2 as a prognostic marker has been demonstrated in sporadic studies. These findings suggested that CASC2 might play an important role in human cancers and melanoma. More efforts are warranted to examine the function role of CASC2 in other cancer types. Further validation is also needed to promote its development to be a clinically utilizable prognostic biomarker.

The role of lncRNA CASC2 on prognosis of malignant tumors: a meta-analysis and bioinformatics

Background

Cancer susceptibility candidate 2 (CASC2) is characterized as a tumor suppressor, which was first identified to be downregulated in endometrial carcinoma. Accumulating evidence was provided to testify the function of CASC2 in malignant tumors. However, a systematic and quantitative assessment is not available. The present study was designed to evaluate the role of CASC2 in multiple carcinomas through meta-analysis and bioinformatics.

Materials and methods

A systematic assessment of the relationship of CASC2 with tumors was performed by using several computerized databases from inception to December 1, 2017. Pooled HR with 95% CI was calculated to summarize the effect. The data on prognosis of malignant tumors were also downloaded from The Cancer Genome Atlas (TCGA) project, OncoLnc, TANRIC and lncRNAtor database.

Results

A total of 13 studies with 966 cancer patients were pooled in the analysis to evaluate the prognostic value of CASC2 in multiple tumors and the clinical features. The results of the meta-analysis revealed that low expression levels of CASC2 were associated with poor overall survival (OS) (pooled HR=0.39, 95% CI: 0.28–0.53, P<0.0001). CASC2 obviously has a negative correlation with advanced tumor node metastasis (TNM) stage, lymph node metastasis (LNM) and T stage, respectively (P<0.05). There was, however, no significant difference in gender, distant metastasis and high differentiation (P>0.05). In the Kaplan–Meier curves with log-rank analysis, higher expression of CASC2 was positively correlated with longer survival time than patients with a lower level (P<0.05), including kidney renal clear cell carcinoma, brain lower grade glioma, pancreatic adenocarcinoma and sarcoma.

Conclusion

Findings from this meta-analysis suggest that lower expression of CASC2 is associated with poorer prognosis of cancers, as well as advanced TNM, LNM and T stage. Data from the bioinformatics analysis revealed that higher expression of CASC2 was related to longer OS in patients with malignant tumors.

NFIX Circular RNA Promotes Glioma Progression by Regulating miR-34a-5p via Notch Signaling Pathway

Objective: The present study aimed to explore the association between NFIX circular RNA (circNFIX) and miR-34a-5p in glioma. Furthermore, this study investigated the influence that circNFIX has on glioma progression through the upregulation of NOTCH1 via the Notch signaling pathway by sponging miR-34a-5p.

Methods: We applied five methods, CIRCexplorer2, circRNA-finder, CIRI, find-circ and MapSplice2, to screen for circRNAs with differential expression between three glioma tissue samples and three paired normal tissue samples. The GSEA software was used to confirm whether significantly different pathways were activated or inactivated in glioma tissues. The binding sites between circNFIX and miR-34a-5p were confirmed by TargetScan. QRT-PCR and western blot were used to measure the relative expression levels of circNFIX, miR-34a-5p and NOTCH and identify their correlation in glioma. RNA immunoprecipitation (RIP) validated the binding relationship between circNFIX and miR-34a-5p, while the targeted relationship between NOTCH1 and miR-34a-5p was verified by a dual luciferase reporter assay. Cell viability and mobility were examined by a CCK-8 assay and wound healing assay, and a flow cytometry assay was employed to analyze cell apoptosis. The nude mouse transplantation tumor experiment verified that si-circNFIX exerted a suppressive effect on glioma progression in vivo.

Results: Twelve circRNAs were differentially expressed between the tissue types. Of those, circNFIX was the sole circRNA to be overexpressed in glioma among the five methods of finding circRNAs. In addition, the Notch signaling pathway was considerably upregulated in tumor tissues compared with the paired normal brain tissues. It was determined that circNFIX acted as a sponge of miR-34a-5p, a miRNA that targeted NOTCH1. Downregulation of circNFIX and upregulation of miR-34a-5p both inhibited cell propagation and migration. Furthermore, a miR-34a-5p inhibitor neutralized the suppressive effect of si-circNFIX on glioma cells. Si-circNFIX and miR-34a-5p mimics promoted cell apoptosis. Moreover, it was demonstrated in vivo that si-circNFIX could suppress glioma growth by regulating miR-34a-5p and NOTCH1.

Conclusion: CircNFIX was markedly upregulated in glioma cells. CircNFIX could regulate NOTCH1 and the Notch signaling pathway to promote glioma progression by sponging miR-34a-5p via the Notch signaling pathway. This finding provided a deeper insight into the function of circNFIX in human glioma cancer progression.

Exploring Long Noncoding RNAs in Glioblastoma: Regulatory Mechanisms and Clinical Potentials

Gliomas are primary brain tumors presumably derived from glial cells. The WHO grade IV glioblastoma (GBM), characterized by rapid cell proliferation, easily recrudescent, high morbidity, and mortality, is the most common, devastating, and lethal gliomas. Molecular mechanisms underlying the pathogenesis and progression of GBMs with potential diagnostic and therapeutic value have been explored industriously. With the advent of high-throughput technologies, numerous long noncoding RNAs (lncRNAs) aberrantly expressed in GBMs were discovered recently, some of them probably involved in GBM initiation, malignant progression, relapse and resistant to therapy, or showing diagnostic and prognostic value. In this review, we summarized the profile of lncRNAs that has been extensively investigated in glioma research, with a focus on their regulatory mechanisms. Then, their diagnostic, prognostic, and therapeutic implications were also discussed.

MiR-129-5p inhibits glioma cell progression in vitro and in vivo by targeting TGIF2

This study purposed to explore the correlation between miR-129-5p and TGIF2 and their impacts on glioma cell progression. Differentially expressed miRNA was screened through microarray analysis. MiR-129-5p expression levels in glioma tissues and cells were measured by qRT-PCR. CCK-8 assay, flow cytometer, transwell assay and wound-healing assay were employed to detect cell proliferation, apoptosis and cycle, invasiveness and migration, respectively. Dual-luciferase reporting assay was performed to confirm the targeted relationship between miR-129-5p and TGIF2. The effects of TGIF2 expression on cell biological functions were also investigated using the indicated methods. Tumour xenograft was applied to explore the impact of miR-129-5p on tumorigenesis in vivo. MiR-129-5p expression was down-regulated in both glioma tissues and glioma cells, while TGIF2 expression was aberrantly higher than normal level. Dual-luciferase reporter assay validated the targeting relation between miR-129-5p and TGIF2. Overexpression of miR-129-5p or down-regulation of TGIF2 inhibited the proliferation, invasion and migration capacity of glioma cells U87 and U251, and meanwhile blocked the cell cycle as well as induced cell apoptosis. MiR-129-5p overexpression repressed the tumour development in vivo. MiR-129-5p and TGIF2 had opposite biological functions in glioma cells. MiR-129-5p could inhibit glioma cell progression by targeting TGIF2, shining light for the development of target treatment for glioma.

Upregulation of lncRNA CASC2 Suppresses Cell Proliferation and Metastasis of Breast Cancer via Inactivation of the TGF-β Signaling Pathway

Breast cancer is one of the major malignancies with a mounting mortality rate in the world. Long noncoding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) has been identified to regulate the initiation and progression of multiple tumorous diseases according to previous studies. However, its biological role has been rarely reported in breast cancer. In the present study, lncRNA CASC2 was found to be significantly downregulated in breast cancer tissues and cell lines using real-time quantitative PCR. Furthermore, gain-of-function assays demonstrated that overexpression of lncRNA CASC2 significantly repressed breast cancer cell proliferation and metastasis. Moreover, CASC2 induced cell cycle arrest and much more early apoptosis of breast cancer. Additionally, based on the above research, we illustrated that inactivation of the TGF-β signaling pathway was involved in the function of lncRNA CASC2. Collectively, lncRNA CASC2 was a key factor in the tumorigenesis and malignancy of breast cancer, suggesting it may possibly be a potential therapy target for the treatment of breast cancer.

Long non-coding RNA CASC2 inhibits tumorigenesis via the miR-181a/PLXNC1 axis in melanoma

Melanoma is the most malignant and aggressive form of skin carcinoma originating in the pigment-producing melanocytes. In this study, to further investigate the molecular mechanisms of the development and progression of melanoma, we explored the impacts of long non-coding RNA (lncRNA) CASC2 on melanoma cell functions. Microarray analysis was carried out to identify the expression of lncRNA CASC2 in melanoma cells. MiR-181a was predicted as a sponging target of CASC2 by miRcode, while the 3'-UTR of Plexin C1 (PLXNC1) was a potential target of miR-181a according to the TargetScan database. The correlation among CASC2, miR-181a, and PLXNC1 was verified by dual luciferase reporter assay and qRT-PCR. After manipulation of CASC2, miR-181a and PLXNC1 expression with transfection in A375 and M14 cells, cell viability, apoptosis, and invasive ability were evaluated using CCK-8, flow cytometry and Transwell assays, respectively. A low expression of CASC2 was detected in melanoma tissues and cells. Dual luciferase reporting assay confirmed that miR-181a targeted the 3'-UTR of PLXNC1. Furthermore, CASC2 could efficiently sponge miR-181a, thereby facilitating the expression of PLXNC1. Up-regulation of CASC2 suppressed the cell proliferation and invasion, but induced the apoptosis of melanoma cells. Our results demonstrated that lncRNA CASC2 can promote PLXNC1 expression by sponging miR-181a, thereby inhibiting the proliferation and invasion of melanoma cells, indicating that lncRNA CASC2 functions via the miR-181a/PLXNC1 axis in melanoma.

Long non-coding RNAs in glioma progression

Glioma is one of most malignant primary tumors of the brain. However, due to a lack of effective means for diagnosing and treating glioma, the prognosis of glioma patients remains poor. Therefore, understanding the molecular mechanism of glioma progression is essential for effective treatment. Long non-coding RNAs (lncRNAs) are novel regulators of gene expression at the transcriptional, post-transcriptional and epigenetic levels. Recent evidence indicates that lncRNAs may play important roles in regulating the progression of glioma. In this article, we review the expression profile of lncRNAs in glioma and discuss the functions and known mechanisms of several representative lncRNAs in detail, as well as the prospects of lncRNAs as diagnostic and prognostic biomarkers and therapeutic targets.

Long non-coding RNA CCAT1 promotes multiple myeloma progression by acting as a molecular sponge of miR-181a-5p to modulate HOXA1 expression

Multiple myeloma (MM) is the second most common hematological cancer all over the world. Long non-coding RNA (lncRNA) colon cancer associated transcript-1 (CCAT1) has been reported to play important roles in the development and progression of multiple human malignancies. However, little is known about its functional role and molecular mechanism in MM. The aim of this study was to investigate the clinical and biological significance of CCAT1 in MM. Our data showed that the relative expression levels of CCAT1 were significantly upregulated in MM tissues and cell lines compared with healthy donors and normal plasma cells (nPCs). High expression of CCAT1 was correlated shorter overall survival of MM patients. CCAT1 knockdown significantly inhibited cell proliferation, induced cell cycle arrest at G0/G1 phase and promoted cell apoptosis in vitro, and suppressed tumor growth in vivo. MiR-181a-5p was a direct target of CCAT1, and repression of miR-181a-5p could rescue the inhibition of CCAT1 knockdown on MM progression. In addition, CCAT1 positively regulated HOXA1 expression through sponging miR-181a-5p in MM cells.taken together, lncRNA CCAT1 exerted an oncogenic role in MM by acting as a ceRNA of miR-181a-5p. These results suggest that CCAT1 may serve as a novel diagnostic marker and therapeutic target for MM.