Clinical significance of the expression of long non-coding RNA PVT1 in glioma

LncRNA-PVT1 was identified as a key regulator for TMZ resistance and STAT-related pathway in glioma

BACKGROUND

PVT1, a previously uncharacterized lncRNA, was identified as a critical regulator involved in multiple functions in tumor, including cell proliferation, cell motility, angiogenesis and so on. However, the clinical significance and underlying mechanism of PVT1 was not be fully explored in glioma.

METHODS

In this study, 1210 glioma samples with transcriptome data from three independent databases (CGGA RNA-seq, TCGA RNA-seq and GSE16011 cohorts) were enrolled in this study. Clinical information and genomic profiles containing somatic mutations and DNA copy numbers were collected from TCGA cohort. The R software was performed for statistical calculations and graphics. Furthermore, we validated the function of PVT1 in vitro.

RESULTS

The results indicated that higher PVT1 expression was associated with aggressive progression of glioma. Cases with higher PVT1 expression always accompanied by PTEN and EGFR alteration. In addition, functional analyses and western blot results suggested that PVT1 inhibited the sensitivity of TMZ chemotherapy via JAK/STAT signaling. Meanwhile, knockdown of PVT1 increased the sensitivity of TZM chemotherapy in vitro. Finally, high PVT1 expression was associated with reduced survival time and may serve as a strong prognostic indicator for gliomas.

CONCLUSIONS

This study demonstrated that PVT1 expression strongly correlated with tumor progression and chemo-resistance. PVT1 may become a potential biomarker for the diagnosis and treatment in glioma.

LncRNA as potential biomarker and therapeutic target in glioma

Glioma is the most frequent type of malignant tumor in the central nervous system, accounting for about 80% of primary malignant brain tumors, usually with a poor prognosis. A number of studies have been conducted on the molecular abnormalities in glioma to further understand its pathogenesis, and it has been found that lncRNAs (long non-coding RNA) play a key role in angiogenesis, tumor growth, infiltration and metastasis of glioma. Since specific lncRNAs have an aberrant expression in brain tissue, cerebrospinal fluid as well as peripheral circulation of glioma patients, they are considered to be potential biomarkers. This review focuses on the biological characteristics of lncRNA and its value as a biomarker for glioma diagnosis and prognosis. Moreover, in view of the role of lncRNAs in glioma proliferation and chemoradiotherapy resistance, we discussed the feasibility for lncRNAs as therapeutic targets. Finally, the persisting deficiencies and future prospects of using lncRNAs as clinical biomarkers and therapeutic targets were concluded.

Targeting long non-coding RNA PVT1/TGF-β/Smad by p53 prevents glioma progression

Glioma is a primary intracranial malignant tumor with poor prognosis, and its pathogenesis is unclear. This study discussed the impact of p53/lncRNA plasmacytoma variant translocation 1 (lncRNA PVT1)/transforming growth factor beta (TGF-β)/Smad axis on the biological characteristics of glioma. Glioma and normal tissues were collected, in which relative lncRNA PVT1 and p53 expression was assessed. Pearson’s analysis was adopted for the correlation analysis between lncRNA PVT1 and p53. Short interfering RNA (siRNA) against lncRNA PVT1 (siRNA-PVT1), siRNA-p53 or both was transfected into the glioma cells to evaluate effects of lncRNA PVT1 and p53 on cell proliferation, migration, invasion, and apoptosis. Mouse xenograft model of glioma was established to verify function of lncRNA PVT1 and p53 in vivo. Relationship among p53, lncRNA PVT1 and TGF-β/Smad was predicted and confirmed. Glioma tissues and cells showed downregulated p53 expression and increased lncRNA PVT1 expression. An adverse relationship was noted between p53 expression and lncRNA PVT1 expression. p53 was shown to be enriched in the lncRNA PVT1 promoter region and resulted in its suppression. p53 inhibited glioma cell proliferation, migration, and invasion, and induced apoptosis as well as arrested tumor growth by downregulating lncRNA PVT1. LncRNA PVT1was found to bind to TGF-β and activate TGF-β/Smad pathway, promoting progression of glioma. Consequently, p53 exerts anti-oncogenic function on glioma development by suppressing lncRNA PVT1 and subsequently inactivating TGF-β/Smad pathway.

Comprehensive Analysis of REST/NRSF Gene in Glioma and Its ceRNA Network Identification

We sought to clarify the clinical relationship between REST/NRSF expression and the prognosis of glioma and explore the REST-associated competitive endogenous RNA (ceRNA) network in glioma. We downloaded RNA-seq, miRNA-seq and correlated clinical data of 670 glioma patients from The Cancer Genome Atlas and analyzed the correlation between REST expression, clinical characteristics and prognosis. Differentially expressed genes (DEGs) were identified with DESeq2 and analyzed with Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) using the Profiler package. Starbase was used to explore the regulatory interaction between REST and miRNAs or LncRNAs. The lncRNA-miRNA-REST ceRNA network was constructed with Cytoscape. RT-qPCR, WB, CCK8, wound-healing, and luciferase assays were performed to validate the ceRNA network. Results showed that REST expression was significantly higher in glioma patients than normal samples. Higher REST expression was significantly associated with worse overall survival, progression-free interval, and worse disease-specific survival in glioma patients. The DEGs of mRNA, miRNA, and lncRNA were identified, and GO and KEGG enrichment analyses were performed. Finally, REST-associated ceRNA networks, including NR2F2-AS1-miR129-REST and HOTAIRM1-miR137-REST, were experimentally validated. Thus, REST may be a prognostic biomarker and therapeutic target in glioma, and its regulatory network validated in this study may provide insights into glioma's molecular regulatory mechanisms.

Depleting SOX2 improves ischemic stroke via lncRNA PVT1/microRNA-24-3p/STAT3 axis

Objectives

Studies have widely explored in the filed of ischemic stroke (IS) with their focus on transcription factors. However, few studies have pivoted on sex determining region Y-box 2 (SOX2) in IS. Thus, this study is launched to figure out the mechanisms of SOX2 in IS.

Methods

Rat middle cerebral artery occlusion (MCAO) was established as a stroke model. MCAO rats were injected with depleted SOX2 or long non-coding RNA plasmacytoma variant translocation 1 (PVT1) to explore their roles in neurological deficits, cerebral water content, neuron survival, apoptosis and oxidative stress. The relationship among SOX2, PVT1, microRNA (miR)-24-3p and signal transducer and activator of transcription 3 (STAT3) was verified by a series of experiments.

Results

SOX2, PVT1 and STAT3 were highly expressed while miR-24-3p was poorly expressed in cerebral cortex tissues of MCAO rats. Depleted SOX2 or PVT1 alleviated brain injury in MCAO rats as reflected by neuronal apoptosis and oxidative stress restriction, brain water content reduction, and neurological deficit and neuron survival improvements. Overexpression of PVT1 functioned oppositely. Restored miR-24-3p abolished PVT1 overexpression-induced brain injury in MCAO rats. SOX2 directly promoted PVT1 expression and further increased STAT3 by sponging miR-24-3p.

Conclusion

This study presents that depleting SOX2 improves IS via PVT1/miR-24-3p/STAT3 axis which may broaden our knowledge about the mechanisms of SOX2/PVT1/miR-24-3p/STAT3 axis and provide a reference of therapy for IS.

Long Non-Coding RNAs in Diagnosis, Treatment, Prognosis, and Progression of Glioma: A State-of-the-Art Review

Glioma is the most common malignant central nervous system tumor with significant mortality and morbidity. Despite considerable advances, the exact molecular pathways involved in tumor progression are not fully elucidated, and patients commonly face a poor prognosis. Long non-coding RNAs (lncRNAs) have recently drawn extra attention for their potential roles in different types of cancer as well as non-malignant diseases. More than 200 lncRNAs have been reported to be associated with glioma. We aimed to assess the roles of the most investigated lncRNAs in different stages of tumor progression and the mediating molecular pathways in addition to their clinical applications. lncRNAs are involved in different stages of tumor formation, invasion, and progression, including regulating the cell cycle, apoptosis, autophagy, epithelial-to-mesenchymal transition, tumor stemness, angiogenesis, the integrity of the blood-tumor-brain barrier, tumor metabolism, and immunological responses. The well-known oncogenic lncRNAs, which are upregulated in glioma, are H19, HOTAIR, PVT1, UCA1, XIST, CRNDE, FOXD2-AS1, ANRIL, HOXA11-AS, TP73-AS1, and DANCR. On the other hand, MEG3, GAS5, CCASC2, and TUSC7 are tumor suppressor lncRNAs, which are downregulated. While most studies reported oncogenic effects for MALAT1, TUG1, and NEAT1, there are some controversies regarding these lncRNAs. Expression levels of lncRNAs can be associated with tumor grade, survival, treatment response (chemotherapy drugs or radiotherapy), and overall prognosis. Moreover, circulatory levels of lncRNAs, such as MALAT1, H19, HOTAIR, NEAT1, TUG1, GAS5, LINK-A, and TUSC7, can provide non-invasive diagnostic and prognostic tools. Modulation of expression of lncRNAs using antisense oligonucleotides can lead to novel therapeutics. Notably, a profound understanding of the underlying molecular pathways involved in the function of lncRNAs is required to develop novel therapeutic targets. More investigations with large sample sizes and increased focus on in-vivo models are required to expand our understanding of the potential roles and application of lncRNAs in glioma.

8q24.21 Locus: A Paradigm to Link Non-Coding RNAs, Genome Polymorphisms and Cancer

The majority of the human genome is comprised of non-protein-coding genes, but the relevance of non-coding RNAs in complex diseases has yet to be fully elucidated. One class of non-coding RNAs is long non-coding RNAs or lncRNAs, many of which have been identified to play a range of roles in transcription and translation. While the clinical importance of the majority of lncRNAs have yet to be identified, it is puzzling that a large number of disease-associated genetic variations are seen in lncRNA genes. The 8q24.21 locus is rich in lncRNAs and very few protein-coding genes are located in this region. Interestingly, the 8q24.21 region is also a hot spot for genetic variants associated with an increased risk of cancer. Research focusing on the lncRNAs in this area of the genome has indicated clinical relevance of lncRNAs in different cancers. In this review, we summarise the lncRNAs in the 8q24.21 region with respect to their role in cancer and discuss the potential impact of cancer-associated genetic polymorphisms on the function of lncRNAs in initiation and progression of cancer.

Long Intergenic Non-Protein Coding RNA 1094 Promotes Initiation and Progression of Glioblastoma by Promoting microRNA-577-Regulated Stabilization of Brain-Derived Neurotrophic Factor

Purpose

The long intergenic non-protein coding RNA 1094 (LINC01094) plays a vital role in the oncogenicity of clear cell renal cell carcinoma. However, its expression profile and detailed roles in glioblastoma (GBM) remain unknown. In this study, we mainly investigated the expression and roles of LINC01094 in GBM and focused on the mechanism by which LINC01094 regulates the malignant characteristics of GBM.

Patients and Methods

LINC01094 expression in GBM was determined with quantitative reverse transcription polymerase chain reaction. The proliferation, apoptosis, migration, invasion in vitro, and tumor growth in vivo of GBM cells were evaluated using Cell Counting Kit-8 assay, flow cytometry analysis, migration assay, invasion assay, and tumor xenograft models, respectively.

Results

LINC01094 was overexpressed in GBM tissues and cell lines. Moreover, increased LINC01094 expression was associated with adverse clinicopathological parameters in patients with GBM. Loss of LINC01094 inhibited GBM cell proliferation, migration, and invasion; promoted cell apoptosis; and suppressed tumor growth in vivo. Mechanically, LINC01094 functioned as a molecular sponge for microRNA-577 (miR-577) and consequently enhanced the expression of brain-derived neurotrophic factor (BDNF) in GBM cells. Both miR-577 inhibition and BDNF expression enhancement reversed LINC01094 deficiency-mediated inhibition of malignant processes in GBM cells.

Conclusion

Our results verified the involvement of the LINC01094/miR-577/BDNF pathway in GBM cells and its enhancing effects on the aggressive behaviors of GBM cells in vitro and in vivo. This pathway may be a novel and promising focus for the future development of targeted therapies for GBM.

Upregulation of lncRNA plasmacytoma variant translocation 1 predicts poor prognosis in patients with muscle-invasive bladder cancer

LncRNA plasmacytoma variant translocation 1 (PVT1) has been recognized as an oncogenic lncRNA, which participates in the migration and invasion of many kinds of cancer cells and the development of cancers. In the present study, we explored its clinical significance and prognostic value in muscle invasive bladder cancer (MIBC).A total of 98 MIBC patients' samples were collected, who had undergone radical cystectomy from the March 2013 to December 2018. The associations between PVT1 expression and clinical data were calculated using the Chi-test. Overall survival curves were determined by the Kaplan-Meier technique and contrasted via log-rank test. We utilized univariate and multivariate Cox proportional hazard models to examine the HR and 95% CI.The expression levels of PVT1 were significantly higher in MIBC tissues than that in normal bladder tissues (P < .001). PVT1 expression was significantly correlated with tumor grade (P = .009), margin (P = .002), T stage (P = .02), and lymph node metastasis (P < .001). MIBC patients with high PVT1 expression level had shorter overall survival than those with low PVT1 expression level (log-rank test, P = .004). Multivariate Cox regression analysis showed that PVT1 expression level (HR = 2.381, 95% CI: 1.821-7.012, P = .014) was an independent factor in predicting the overall survival of MIBC patients.In summary, increased PVT1 expression in MIBC patients is correlated with a higher MIBC stage and is significantly associated with poor prognosis for MIBC patients, which may provide new insights into new therapeutic strategy and postoperative intervention against bladder cancer.

Lowly expressed lncRNA PVT1 suppresses proliferation and advances apoptosis of glioma cells through up-regulating microRNA-128-1-5p and inhibiting PTBP1

BACKGROUND

Glioma is a primary intracranial malignancy with poor prognosis, of which the pathogenesis remains to be elucidated. Therein, the aim of this study is to discuss the impacts of lncRNA plasmacytoma variant translocation 1 (PVT1)/microRNA-128-1-5p (miR-128-1-5p)/polypyrimidine tract-binding protein 1 (PTBP1) axis on the biological characteristics of glioma cells.

METHODS

Glioma tissue samples (72 cases) and normal brain tissue samples (35 cases) were harvested. The expression of PVT1, miR-128-1-5p and PTBP1 in glioma tissues and cells was detected. Glioma cells were transfected with sh-PVT1, miR-128-1-5p mimics or miR-128-1-5p inhibitors to verify the impacts of PVT1 and miR-128-1-5p on DNA damage, cell colony formation, invasion, proliferation, migration and apoptosis of glioma U87 and U251 cells. The growth of transplanted tumor was tested by tumor xenograft in nude mice. The combination of PVT1 and miR-128-1-5p and the targeting relationship between miR-128-1-5p and PTBP1 were verified.

RESULTS

PVT1 and PTBP1 expression was enhanced and miR-128-1-5p expression was degraded in glioma tissues and cells. Overexpressed miR-128-1-5p and lowly-expressed PVT1 promoted DNA damage, suppressed colony formation, invasion, proliferation and migration as well as boosted apoptosis of U251 and U87 cells. Up-regulating miR-128-1-5p and down-regulating PVT1 reduced transplanted tumor volume and weight of glioma in mice. Low expression miR-128-1-5p reversed the effect of low expression PVT1 on the biological characteristics of glioma cells. PVT1 specifically bound to miR-128-1-5p and PTBP1 was the target gene of miR-128-1-5p.

CONCLUSION

This study suggests that down-regulated PVT1 or up-regulated miR-128-1-5p boosts apoptosis and attenuates proliferation of glioma cells by inhibiting PTBP1 expression. This study is essential for finding new therapeutic targets for glioma.

Competing endogenous RNA network analysis reveals potential long non-coding RNAs as predictive biomarkers of gastric cancer

Gastric cancer (GC) is one of the most frequently occurring life-threatening malignancies worldwide. Due to its high mortality rate, the discovery of putative biomarkers that may be sensitive and specific to GC is of seminal importance. Long non-coding RNAs (lncRNAs) are non-translatable RNAs whose transcript length exceeds 200 base pairs. The dysregulation of lncRNA expression plays a key role in tumorigenesis and development. In the present study, the expression profiles of lncRNAs, microRNAs and mRNAs of 361 GC tissues (and 32 normal gastric tissues) were downloaded from The Cancer Genome Atlas database. Furthermore, differentially expressed RNAs were analyzed by the DEseq package. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses confirmed some significant dysregulated signaling pathways and target RNAs. As a result, an lncRNA-associated competing endogenous RNA (ceRNA) network was constructed. Kaplan-Meier analysis of the differentially expressed RNAs associated with GC pathogenesis confirmed that the lncRNAs PVT1, HAND2-AS1 and ZNF667-AS1 were potentially associated with the prognosis of GC (P<0.05). The present study suggests the mechanism of ceRNA networks in GC, and further demonstrates that aberrant lncRNA expression may be used as an effective diagnostic tool (or target) for the prognosis of GC.

Long Non-Coding RNA PVT1 Regulates BAMBI To Promote Tumor Progression In Non-Small Cell Lung Cancer By Sponging miR-17-5p

Background

Non-small cell lung cancer (NSCLC) is a common malignancy over the world. Previous report indicated that the plasmacytoma variant translocation 1 (PVT1) has been documented to function as an oncogene in various types of human cancers. However, the biological mechanism of PVT1 was still rarely reported in NSCLC.

Methods

The levels of PVT1, miR-17-5p, and bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) in NSCLC tissues (n=64) and cells (H1299 and A549) were detected by qRT-PCR and immunohistochemistry (IHC). The protein level of BAMBI was measured by Western blot assay. Cell viability and apoptotic rate were evaluated by MTT assay and flow cytometry, respectively. The migrated and invaded abilities were assessed by Transwell assay and Wound healing assay. The interactions between miR-17-5p and PVT1 or BAMBI were predicted by starBase v2.0 and TargetScan, respectively, and then dual-luciferase reporter assay and RNA pull-down assay were performed to verify these interactions. The mice model experiments were constructed to further validate the roles of PVT1 in vivo.

Results

The levels of PVT1 and BAMBI were both apparently increased, and miR-17-5p was declined in NSCLC tissues and cells. The depletion of PVT1 or BAMBI blocked cell viability, migrated and invaded abilities but impelled apoptotic rate in A549 and H1299 cells. PVT1 was validated as a sponge to miR-17-5p and BAMBI was a direct target of miR-17-5p. PVT1 promoted cell viability, migrated and invaded abilities but repressed apoptotic rate by targeting BAMBI. MiR-17-5p regulated cell behaviors mediated by PVT1. PVT1 silencing decreased BAMBI expression by sponging miR-17-5p. In addition, PVT1 knockdown blocked the xenograft tumor growth in vivo.

Conclusion

These results manifested that PVT1 modulated BAMBI to promote tumor progression in NSCLC by sponging miR-17-5p. Thus, the novel regulatory pathway may provide a new therapeutic target for NSCLC patients.

PVT1 Promotes Cancer Progression via MicroRNAs

Non-coding RNA (ncRNA) plays a regulatory role in a variety of cellular activities. And long non-coding RNA (lncRNA) is one of the important kinds of ncRNA. Previous studies have shown that various lncRNAs are involved in the progression of cancer. LncRNA plasmacytoma variant translocation 1 (PVT1) is a newly discovered oncogenic factor that has been confirmed to be overexpressed in many cancer cells. Moreover, the role of PVT1 in cancer development is closely linked to microRNAs (miRNAs). PVT1 can act as a "sponge" for miRNAs to inhibit their activities, thereby affecting proliferation, invasion, and angiogenesis of cancer. In addition, PVT1 itself can be spliced and processed into several miRNAs such as miR-1204 and miR-1207, which can also regulate the development of cancer. This review summarizes various pathways through which PVT1 regulates the progression of cancer via miRNAs. We also propose additional regulatory mechanisms of PVT1 and their potential clinical applications.

Long noncoding RNA PVT1: A highly dysregulated gene in malignancy

Recent studies have verified the contribution of several long noncoding RNAs (lncRNAs) in the carcinogenesis. Among the highly acknowledged lncRNAs is the human homolog of the plasmacytoma variant translocation gene, which is called PVT1. PVT1 resides near Myc oncogene and regulates the oncogenic process through modulation of several signaling pathways, such as TGF-β, Wnt/ β-catenin, PI3K/AKT, and mTOR pathways. This lncRNA has a circular form as well. Expression analyses and functional studies have appraised the oncogenic roles of PVT1 and circPVT1. Experiments in several cancer cell lines have shown that PVT1 silencing suppresses cancer cell proliferation, whereas its overexpression has the opposite effect. Its silencing has led to the accumulation of cells in the G0/G1 phase and diminished the number of cells in the S phase. Moreover, genome-wide association studies have signified the role of single nucleotide polymorphisms of this lncRNA in conferring risk of lymphoma in different populations. In the current study, we have summarized recent data about the role of PVT1 and circPVT1 in the carcinogenesis process.