The expression pattern of long non-coding RNA PVT1 in tumor tissues and in extracellular vesicles of colorectal cancer correlates with cancer progression

Exosomal RNAs and EZH2: unraveling the molecular dialogue driving tumor progression

The EZH2 gene encodes an enzyme that is part of the epigenetic factor Polycomb Repressive Complex 2 (PRC2). In order to control gene expression, PRC2 mainly modifies chromatin structure. In this complex process, EZH2 methylates histone proteins, which in turn suppresses further RNA transcriptions. As a result, EZH2 dysregulations can occasionally induce abnormal gene expression patterns, which can aid in the development and progression of cancer. Non-coding RNAs significantly impact the expression of EZH2 through epigenetic mechanisms. Meanwhile, normal and cancerous cells frequently release vesicles into the extracellular matrix, also known as exosomes, that occasionally carry RNA molecules from their origin cells, including messenger RNAs, microRNAs, and other non-coding RNAs. Thus exosomes are granted the ability to regulate numerous physiological functions and act as crucial messengers between cells by influencing gene expression in the recipient cell. We conducted this review to focus on EZH2's substantial biological role and the mechanisms that regulate it, driven by the desire to understand the possible impact of exosomal RNAs on EZH2 expression.

Potential of extracellular vesicle cargo as molecular signals in Schizophrenia: a scoping review

The diagnosis of schizophrenia (SCZ) primarily relies on clinical history and mental status assessments by trained professionals. There has been a search for biomarkers to facilitate laboratory diagnosis. Since extracellular vesicles (EVs) communicate with brain cells and can easily cross blood-brain barrier, there is increased interest among experts to explore them as potential molecular signals for disease detection. A scoping review was conducted to provide a comprehensive summary of the existing literature to identify the differentially expressed molecular signals in EVs isolated from SCZ patients. The methodological framework outline provided by Arksey and O'Malley was employed to conduct this scoping review. A systematic search was conducted using a search string across four databases, ultimately leading to selection of 24 relevant studies. Over 1122 differentially expressed biomolecules were identified in EVs extracted from biological fluids and tissues that can be primarily categorized as RNAs, proteins, and metabolites. Among them, 83 biomolecules were identified as validated differentially expressed molecular signals, which included metabolites, circRNAs, lncRNAs, miRNAs, and proteins. These biomolecules were found to affect cellular receptors and intracellular pathways, neurotransmitters, mitochondrial functions, immune-related functions, and metabolic pathways, which could serve as potential biomarkers for SCZ diagnosis.

Identification of MYC and STAT3 for early diagnosis based on the long noncoding RNA-mRNA network and bioinformatics in colorectal cancer

Background

Colorectal cancer (CRC) ranks among the top three cancers globally in both incidence and mortality, posing a significant public health challenge. Most CRC cases are diagnosed at intermediate to advanced stages, and reliable biomarkers for early detection are lacking. Long non-coding RNAs (lncRNAs) have been implicated in various cancers, including CRC, playing key roles in tumor development, progression, and prognosis.

Methods

A comprehensive search of the PubMed database was conducted to identify relevant studies on the early diagnosis of CRC. Bioinformatics analysis was performed to explore lncRNA-mRNA networks, leading to the identification of five potential blood biomarkers. Expression analysis was carried out using the GEPIA and GEO online databases, focusing on MYC and STAT3. Differential expression between normal and CRC tissues was assessed, followed by Receiver Operating Characteristic (ROC) analysis to evaluate the diagnostic potential of these markers. Quantitative Real-Time PCR (qRT-PCR) was performed to validate MYC and STAT3 expression levels, and findings were further confirmed using the Human Protein Atlas (HPA) database.

Results

Database analysis revealed significant differential expression of MYC and STAT3 between normal and CRC tissues. ROC analysis demonstrated the diagnostic potential of these markers. qRT-PCR validation confirmed the differential expression patterns observed in the databases. Validation through the HPA database further supported these findings, confirming the potential of MYC and STAT3 as diagnostic biomarkers for CRC.

Conclusion

Our results suggest that MYC and STAT3 are promising diagnostic biomarkers for CRC, offering new insights into its pathophysiology and potential for targeted therapies.

lncRNA PVT1: a novel oncogene in multiple cancers

Long noncoding RNAs are involved in epigenetic gene modification, including binding to the chromatin rearrangement complex in pre-transcriptional regulation and to gene promoters in gene expression regulation, as well as acting as microRNA sponges to control messenger RNA levels in post-transcriptional regulation. An increasing number of studies have found that long noncoding RNA plasmacytoma variant translocation 1 (PVT1) plays an important role in cancer development. In this review of a large number of studies on PVT1, we found that PVT1 is closely related to tumor onset, proliferation, invasion, epithelial–mesenchymal transformation, and apoptosis, as well as poor prognosis and radiotherapy and chemotherapy resistance in some cancers. This review comprehensively describes PVT1 expression in various cancers and presents novel approaches to the diagnosis and treatment of cancer.

Tumour Derived Extracellular Vesicles: Challenging Target to Blunt Tumour Immune Evasion

Simple Summary

Tumour onset and development occur because of specific immune support. The immune system, which is originally able to perceive and eliminate incipient cancer cells, becomes suppressed and hijacked by cancer. For these purposes, tumour cells use extracellular vesicles (TEVs). Specific molecular composition allows TEVs to reprogram immune cells towards tumour tolerance. Circulating TEVs move from their site of origin to other organs, preparing “a fertile soil” for metastasis formation. This implies that TEV molecular content can provide a valuable tool for cancer biomarker discovery and potential targets to reshape the immune system into tumour recognition and eradication.

Abstract

Control of the immune response is crucial for tumour onset and progression. Tumour cells handle the immune reaction by means of secreted factors and extracellular vesicles (EV). Tumour-derived extracellular vesicles (TEV) play key roles in immune reprogramming by delivering their cargo to different immune cells. Tumour-surrounding tissues also contribute to tumour immune editing and evasion, tumour progression, and drug resistance via locally released TEV. Moreover, the increase in circulating TEV has suggested their underpinning role in tumour dissemination. This review brings together data referring to TEV-driven immune regulation and antitumour immune suppression. Attention was also dedicated to TEV-mediated drug resistance.

Pioneer Role of Extracellular Vesicles as Modulators of Cancer Initiation in Progression, Drug Therapy, and Vaccine Prospects

Cancer is one of the leading diseases, causing deaths worldwide. Nearly 10 million deaths were reported in 2020 due to cancer alone. Several factors are involved in cancer progressions, such as lifestyle and genetic characteristics. According to a recent report, extracellular vesicles (EVs) are involved in cancer initiation, progression, and therapy failure. EVs can play a major role in intracellular communication, the maintenance of tissue homeostasis, and pathogenesis in several types of diseases. In a healthy person, EVs carry different cargoes, such as miRNA, lncRNA etc., to help other body functions. On the other hand, the same EV in a tumor microenvironment carries cargoes such as miRNA, lncRNA, etc., to initiate or help cancer progression at various stages. These stages may include the proliferation of cells and escape from apoptosis, angiogenesis, cell invasion, and metastasis, reprogramming energy metabolism, evasion of the immune response, and transfer of mutations. Tumor-derived EVs manipulate by altering normal functions of the body and affect the epigenetics of normal cells by limiting the genetic makeup through transferring mutations, histone modifications, etc. Tumor-derived EVs also pose therapy resistance through transferring drug efflux pumps and posing multiple drug resistances. Such EVs can also help as biomarkers for different cancer types and stages, which ultimately help with cancer diagnosis at early stages. In this review, we will shed light on EVs' role in performing normal functions of the body and their position in different hallmarks of cancer, in altering the genetics of a normal cell in a tumor microenvironment, and their role in therapy resistance, as well as the importance of EVs as diagnostic tools.

Diverse roles of EV-RNA in cancer progression

Extracellular vesicles (EVs) have emerged as important players in all aspects of cancer biology. Their function is mediated by their cargo and surface molecules including proteins, lipids, sugars and nucleic acids. RNA in particular is a key mediator of EV function both in normal and cancer cells. This statement is supported by several lines of evidence. First, cells do not always randomly load RNA in EVs, there seems to be a specific manner in which cells populate their EVs with certain RNA molecules. Moreover, cellular uptake of EV-RNA and the secondary compartmentalization of EV-RNA in recipient cells is widely reported, and these RNAs have an impact on all aspects of cancer growth and the anti-tumoral immune response. Additionally, EV-RNA seems to work through various mechanisms of action, highlighting the intricacies of EVs and their RNA cargo as prominent means of inter-cellular communication.

Ketamine Induces Ferroptosis of Liver Cancer Cells by Targeting lncRNA PVT1/miR-214-3p/GPX4

BACKGROUND

Liver cancer ranks the top four malignant cancer type worldwide, which needs effective and safe treatment. Ferroptosis is a novel form of regulated cell death driven by iron-dependent lipid peroxidation and has been regarded as a promising therapeutic target for cancers. In this work, we aimed to study the effects of anesthetic ketamine on proliferation and ferroptosis of liver cancer.

METHODS

Cell viability and proliferation were detected by cell counting kit 8 (CCK-8), colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) assay. Ferroptosis was determined by levels of Fe2+, lipid reactive oxygen species (ROS), and malondialdehyde (MDA). RNA levels of lncPVT1, miR-214-3p, and glutathione peroxidase 4 (GPX4) were checked by real-time PCR assay. Clinical liver tumor samples were collected to detect the levels of long noncoding RNA lncPVT1, miR-214-3p, and GPX4, and their correlation was evaluated by Pearson comparison test. Luciferase reporter gene assay and RNA pulldown were conducted to determine the binding between lncPVT1, miR-214-3p, and GPX4 3'UTR.

RESULTS

Ketamine significantly suppressed viability and proliferation of liver cancer cells both in vitro and in vivo, as well as stimulated ferroptosis, along with decreased expression of lncPVT1 and GPX4. LncPVT1 directly interacted with miR-214-3p to impede its role as a sponge of GPX4. Depletion of lncPVT1 accelerated the ferroptosis of live cancer cells, whereas miR-214-3p inhibition and GPX4 overexpression reversed this effect. Ketamine-induced cell growth suppression and ferroptosis were also suppressed by miR-214-3p inhibition and GPX4 overexpression.

CONCLUSION

In this work, we determined that ketamine suppressed viability of liver cancer cells and induced ferroptosis and identified the possible regulatory mechanism of lncPVT1/miR-214-3p/GPX4 axis.

Exosomes: Emerging modulators of signal transduction in colorectal cancer from molecular understanding to clinical application

Exosomes are small cell derived membrane nano-vesicles that carry various components including lipids, proteins and nucleic acids. There is accumulating evidence that exosomes have a role in tumorigenesis, tumor invasiveness and metastasis. Furthermore, oncogene mutation may influence exosome release from tumor cells. Exosomes may induce colorectal cancer by altering signaling cascades such as the Wnt/β-catenin and KRAS pathways that are involved in cell proliferation, apoptosis, dissemination, angiogenesis, and drug resistance. The aim of this review was to overview recent findings evaluating the association between tumor cells-derived exosomes and their content in modulating signaling pathways in colorectal cancer.

Differentially Expressed Long Noncoding RNAs Involved in FUBP1 Promoting Hepatocellular Carcinoma Cells Proliferation

Background

Far upstream element-binding protein 1 (FUBP1) is reported to be involved in cancer development by regulating the transcription of c-myc gene through binding to far upstream element. Highly expressed FUBP1 was negatively correlated with survival rate of patients with hepatocellular carcinoma (HCC) and could promote the proliferation of HCC cells. However, the downstream mechanism of FUBP1 has not yet been clearly explained. This study is aimed at identifying the expression profiles of long noncoding RNA (lncRNA) in HCC cells in response to FUBP1 overexpression and at investigating the possible lncRNAs that participated in cell proliferation process regulated by FUBP1.

Methods

The overexpression of FUBP1 was mediated by lentiviral infection on 3 different types of HCC cell lines (MHCC97-H, MHCC97-L, and Huh-7). The expression of target genes was detected by quantitative reverse transcription-PCR (RT-PCR) and western blotting assays. Microarray and quantitative RT-PCR were applied to screen the differentially expressed lncRNAs in HCC cells after FUBP1 overexpression. The Cell Counting Kit-8 assay was used to confirm the growth vitality of HCC cells.

Results

The growth vitality of HCC cells was significantly increased after lentivirus infection. A total of 12 lncRNAs had the same expression trend in the 3 HCC cell lines in response to FUBP1 overexpression, including 3 upregulated lncRNAs and 9 downregulated lncRNAs. Coexpression analysis of dysregulated lncRNAs-mRNAs network showed that lnc-LYZ-2 was the lncRNA most relevant to FUBP1. Inhibition of lnc-LYZ-2 could significantly relieve the proproliferation effect of FUBP1 on HCC cells, suggesting that lnc-LYZ-2 was partially involved in proproliferation regulation of FUBP1.

Conclusions

Our results indicated that FUBP1 induced the abnormal expression of lncRNAs and the FUBP1-lncRNAs coexpression network in HCC cells, which could provide theoretical and experimental basis for FUBP1-lncRNAs network involved in HCC development.

Knockdown of PVT1 Suppresses Colorectal Cancer Progression by Regulating MiR-106b-5p/FJX1 Axis

Purpose

Long non-coding RNA plasmacytoma variant translocation 1 (PVT1) has been revealed to involve in the progression of CRC. However, the precise mechanisms of PVT1 in action remain unclear.

Methods

The expression of PVT1, microRNA-106b-5p (miR-106b-5p) and four jointed box 1 (FJX1) was measured using quantitative real-time polymerase chain reaction (qRT-PCR) or Western blot, respectively. Cell proliferation was investigated by 3-(4,5)-dimethylthiahiazo (−z-y1)-3,5-di-phenytetrazoliumromide assay. Transwell assay was used to determine cell migration and invasion. The correlation between miR-106b-5p and PVT1 or FJX1 was confirmed using luciferase reporter assay. The effects of PVT1 in vivo were assessed using mice xenograft model.

Results

PVT1 was up-regulated in CRC tissues and cell lines, especially in CRC tissues with high-grade, and highly expressed PVT1 predicted worse prognosis. Functional experiments demonstrated that PVT1 deletion inhibited CRC cell proliferation, migration and invasion in vitro and suppressed tumor growth in vivo. MiR-106b-5p was confirmed to be a target of PVT1, and inhibition of miR-106b-5p reversed the inhibitory effects of PVT1 knockdown on CRC cell malignant phenotypes. In addition, we found miR-106b-5p directly targeted FJX1, and miR-106b-5p-mediated inhibition on CRC cell proliferation, migration and invasion was attenuated by FJX1 up-regulation. Importantly, it was also proved that PVT1 could indirectly regulate FJX1 expression via targeting miR-106b-5p.

Conclusion

Knockdown of PVT1 impaired cell proliferation, migration and invasion in CRCs via regulating miR-106b-5p/FJX1 axis, which provided a novel insight into the development of therapeutic strategies for CRC patients.

Biomarkers in Colorectal Cancer: Current Research and Future Prospects

Colorectal cancer (CRC) is a leading cause of death worldwide, despite progress made in detection and management through surgery, chemotherapy, radiotherapy, and immunotherapy. Novel therapeutic agents have improved survival in both the adjuvant and advanced disease settings, albeit with an increased risk of toxicity and cost. However, metastatic disease continues to have a poor long-term prognosis and significant challenges remain due to late stage diagnosis and treatment failure. Biomarkers are a key tool in early detection, prognostication, survival, and predicting treatment response. The past three decades have seen advances in genomics and molecular pathology of cancer biomarkers, allowing for greater individualization of therapy with a positive impact on survival outcomes. Clinically useful predictive biomarkers aid clinical decision making, such as the presence of KRAS gene mutations predicting benefit from epidermal growth factor receptor (EGFR) inhibiting antibodies. However, few biomarkers have been translated into clinical practice highlighting the need for further investigation. We review a range of protein, DNA and RNA-based biomarkers under investigation for diagnostic, predictive, and prognostic properties for CRC. In particular, long non-coding RNAs (lncRNA), have been investigated as biomarkers in a range of cancers including colorectal cancer. Specifically, we evaluate the potential role of lncRNA plasmacytoma variant translocation 1 (PVT1), an oncogene, as a diagnostic, prognostic, and therapeutic biomarker in colorectal cancer.

Population Differentiation at the PVT1 Gene Locus: Implications for Prostate Cancer

Genetic variation in susceptibility to complex diseases, such as cancer, is well-established. Enrichment of disease associated alleles in specific populations could have implications for disease incidence and prevalence. Prostate cancer (PCa) is a disease with well-established higher incidence, prevalence, and worse outcomes among men of African ancestry in comparison to other populations. PCa is a multi-factorial, complex disease, but the exact mechanisms for its development and progression are unclear. The gene desert located on chromosome 8q24 is associated with aggressiveness of PCa. Interestingly, the non-protein coding gene locus Plasmacytoma Variant Translocation (PVT1) is present at chromosome 8q24 and is overexpressed in PCa. PVT1 gives rise to multiple transcripts with potentially different molecular and cellular functions. In an analysis of the PVT1 locus using data from the 1000 Genomes Project, we found the chromosomal region spanning PVT1 exons 4A and 4B to be highly differentiated between African and non-African populations. We further investigated levels of gene expression of PVT1 exons 4A and 4B and observed significant overexpression of these exons in PCa tissues relative to benign prostatic hyperplasia and to normal prostate tissues obtained from men of African ancestry. These results indicate that PVT1 exons 4A and 4B may have clinical implications in PCa a conclusion supported by the observation that transient and stable overexpression of PVT1 exons 4A and 4B significantly induce greater prostate epithelial cell migration and proliferation. We anticipate that further exploration of the role of PVT1 exons 4A and 4B may lead to the development of diagnostic, therapeutic, and other clinical applications in PCa.

The Role of Extracellular Vesicles in the Hallmarks of Cancer and Drug Resistance

Extracellular vesicles (EVs) mediate intercellular signaling and communication, allowing the intercellular exchange of proteins, lipids, and genetic material. Their recognized role in the maintenance of the physiological balance and homeostasis seems to be severely disturbed throughout the carcinogenesis process. Indeed, the modus operandi of cancer implies the highjack of the EV signaling network to support tumor progression in many (if not all) human tumor malignancies. We have reviewed the current evidence for the role of EVs in affecting cancer hallmark traits by: (i) promoting cell proliferation and escape from apoptosis, (ii) sustaining angiogenesis, (iii) contributing to cancer cell invasion and metastasis, (iv) reprogramming energy metabolism, (v) transferring mutations, and (vi) modulating the tumor microenvironment (TME) by evading immune response and promoting inflammation. Special emphasis was given to the role of EVs in the transfer of drug resistant traits and to the EV cargo responsible for this transfer, both between cancer cells or between the microenvironment and tumor cells. Finally, we reviewed evidence for the increased release of EVs by drug resistant cells. A timely and comprehensive understanding of how tumor EVs facilitate tumor initiation, progression, metastasis and drug resistance is instrumental for the development of innovative EV-based therapeutic approaches for cancer.

Signaling in and out: long-noncoding RNAs in tumor hypoxia

Over the past few years, long non-coding RNAs (lncRNAs) are recognized as key regulators of gene expression at chromatin, transcriptional and posttranscriptional level with pivotal roles in various biological and pathological processes, including cancer. Hypoxia, a common feature of the tumor microenvironment, profoundly affects gene expression and is tightly associated with cancer progression. Upon tumor hypoxia, the central regulator HIF (hypoxia-inducible factor) is upregulated and orchestrates transcription reprogramming, contributing to aggressive phenotypes in numerous cancers. Not surprisingly, lncRNAs are also transcriptional targets of HIF and serve as effectors of hypoxia response. Indeed, the number of hypoxia-associated lncRNAs (HALs) identified has risen sharply, illustrating the expanding roles of lncRNAs in hypoxia signaling cascade and responses. Moreover, through extra-cellular vesicles, lncRNAs could transmit hypoxia responses between cancer cells and the associated microenvironment. Notably, the aberrantly expressed cellular or exosomal HALs can serve as potential prognostic markers and therapeutic targets. In this review, we provide an update of the current knowledge about the expression, involvement and potential clinical impact of lncRNAs in tumor hypoxia, with special focus on their unique molecular regulation of HIF cascade and hypoxia-induced malignant progression.

Oncogenic Role of PVT1 and Therapeutic Implications

PVT1, a long non-coding RNA has been implicated in a variety of human cancers. Recent advancements have led to increasing discovery of the critical roles of PVT1 in cancer initiation and progression. Novel insight is emerging about PVT1's mechanism of action in different cancers. Identifying and understanding the variety of activities of PVT1 involved in cancers is a necessity for the development of PVT1 as a diagnostic biomarker or therapeutic target in cancers where PVT1 is dysregulated. PVT1's varied activities include overexpression, modulation of miRNA expression, protein interactions, targeting of regulatory genes, formation of fusion genes, functioning as a competing endogenous RNA (ceRNA), and interactions with MYC, among many others. Furthermore, bioinformatic analysis of PVT1 interactions in cancers has aided understanding of the numerous pathways involved in PVT1 contribution to carcinogenesis in a cancer type-specific manner. However, these recent findings show that there is much more to be learned to be able to fully exploit PVT1 for cancer prognostication and therapy. In this review, we summarize some of the latest findings on PVT1's oncogenic activities, signaling networks and how targeting these networks can be a strategy for cancer therapy.

Biological and clinical relevance of metastasis-associated long noncoding RNAs in esophageal squamous cell carcinoma: A systematic review

Esophageal squamous cell carcinoma (ESCC) is a foremost cancer-related death worldwide owing to rapid metastasis and poor prognosis. Metastasis, as the most important reason for death, is biologically a multifaceted process involving a range of cell signaling pathways. Long noncoding RNAs (lncRNAs), as transcriptional regulators, can regulate numerous genomic processes and cellular processes such as cell proliferation, migration, and invasion. LncRNAs have also been shown to involve in/regulate the cancer metastasis-related signaling pathways. Hence, they have increasingly been brought to international attention in molecular oncology research. A number of researchers have attempted to reveal the biological and clinical relevance of lncRNAs in ESCC tumourigenesis and metastasis. The aberrant expression of these molecules in ESCC has regularly been reported to involve in various cellular processes and clinical features, including diagnosis, prognosis, and therapeutic responses. Here, we especially consider the pathways in which lncRNAs act as metastasis-mediated effectors, mainly by interacting with epithelial-mesenchymal transition-associated factors. We review the biological roles of lncRNAs through involving in ESCC metastasis as well as the clinical significance of the metastasis-related lncRNAs in cancer diagnosis and prognosis.

PVT1 Long Non-coding RNA in Gastrointestinal Cancer

Whole genome and transcriptome sequencing technologies have led to the identification of many long non-coding RNAs (lncRNAs) and stimulated the research of their role in health and disease. LncRNAs participate in the regulation of critical signaling pathways including cell growth, motility, apoptosis, and differentiation; and their expression has been found dysregulated in human tumors. Thus, lncRNAs have emerged as new players in the initiation, maintenance and progression of tumorigenesis. PVT1 (plasmacytoma variant translocation 1) lncRNA is located on chromosomal 8q24.21, a large locus frequently amplified in human cancers and predictive of increased cancer risk in genome-wide association studies (GWAS). Combined, colorectal and gastric adenocarcinomas are the most frequent tumor malignancies and also the leading cause of cancer-related deaths worldwide. PVT1 expression is elevated in gastrointestinal tumors and correlates with poor patient prognosis. In this review, we discuss the mechanisms of action underlying PVT1 oncogenic role in colorectal and gastric cancer such as MYC upregulation, miRNA production, competitive endogenous RNA (ceRNA) function, protein stabilization, and epigenetic regulation. We also illustrate the potential role of PVT1 as prognostic biomarker and its relationship with resistance to current chemotherapeutic treatments.

Exosomal Long NonCoding Rnas as Cancer Biomarkers and Therapeutic Targets

Extensive study of extracellular vesicles began about ten years ago. Exosomes are extracellular membrane vesicles 30–100 nm in diameter secreted by various types of cells and present in most biological fluids. For a long time they were considered non-functional cellular components. However, it has been proven that they serve as a means of intercellular exchange of information. They can move bioactive molecules such as proteins, lipids, RNA, and DNA. Several studies have shown that their contents, including proteins and non-coding nucleic acids, may be of particular interest as biomarkers of diseases. The most promising of all these molecules are non-coding RNAs (ncRNAs), including microRNAs and long non-coding RNAs (lncRNAs). LncRNAs are a large group of non-coding RNAs (ncRNAs) longer than 200 nucleotides. As regulatory factors lncRNAs play an important role in complex cellular processes, such as apoptosis, growth, differentiation, proliferation, etc. Despite many advances in diagnosis and treatment (surgery, radiation therapy, chemotherapy), cancer remains one of the most important public healthcare problems worldwide. Every day brings a better understanding of the role of exosomes in the development of cancer and metastases. Liquid biopsy has been developed as a method for the detection of cancer at an early stage. This is a series of minimally invasive tests of bodily fluids offering the advantage of real-time tracking of the tumour development. In fact, circulating exosomal lncRNAs have been found to be closely linked to processes of oncogenesis, metastasis and treatment. In this paper we review current studies into the functional role of exosomal lncRNAs in cancer and discuss their potential clinical use as diagnostic biomarkers and therapeutic targets for cancer.

Copy number-based quantification assay for non-invasive detection of PVT1-derived transcripts

Background

One of the most important susceptibility loci for cancer is the 8q24 human chromosomal region. The non-protein coding gene locus plasmacytoma variant translocation 1 (PVT1) is located at 8q24 and is dysregulated in prostate cancer. PVT1 gives rise to multiple transcripts which may have different functions. Here, we describe a real-time quantitative polymerase chain reaction (qPCR)-based assay for copy number-based quantitation of PVT1 exons 4A, 4B, and 9 to enable accurate, reproducible, and quantifiable detection.

Methods

PVT1 exons 4A, 4B, and 9 were cloned into a plasmid vector to create standards for subsequent creation of linear standard curves representing a broad range of concentrations. PCR was carried out using SYBR-Green signal detection to quantify PVT1 exons 4A, 4B, and 9. The efficacy of this assay was evaluated by using it to detect these transcripts in prostate epithelial and prostate cancer cell lines, normal and cancerous human prostate tissues, human serum, mouse plasma, and urine samples.

Results

The results indicate that the assay can be used to quantify both low and high copy numbers of PVT1-derived transcripts. This is the first report of a copy number-based quantification assay for non-invasive detection of PVT1 derived transcripts.

Conclusions

This novel assay holds promise for routine non-invasive testing in diseases where PVT1 is dysregulated.

Down-regulated long non-coding RNA PVT1 contributes to gestational diabetes mellitus and preeclampsia via regulation of human trophoblast cells

OBJECTIVE

We aimed to explore the expression level and biological function of lncRNA PVT1 in human trophoblast cells.

METHODS

The expression levels of PVT1 in cancer cell lines, HTR8/SVneo cell, HUVEC cell, the maternal placenta of GDM patients, PE patients and normal pregnancy were detected by qRT-PCR. The cell culture, cell transfection, CCK-8 assay, flow cytometry, wound scratch assay and transwell were carried out to determine the effects of silencing and overexpression of PVT1 on the HTR8/SVneo trophoblast cell line. Nuclear and chromatin RNA fraction assay, RNA-sequencing, western blot and qRT-PCR were conducted to preliminarily explore possible mechanisms.

RESULTS

The relative PVT1 expression level in HTR-8/Svneo cells was higher compared to other cancer cells and HUVEC, and was lower in the GDM and PE placentas than in the normal placentas. The results showed that PVT1 knockdown notably inhibited the proliferation, migration and invasiveness abilities of trophoblast cells, and significantly promoted the apoptosis. Furthermore, overexpression of PVT1 showed the opposite results. We identified 105 differentially expressed genes after PVT1 knockdown, 23 were up-regulated and 82 were down-regulated. GO enrichment analysis and pathway enrichment analysis showed that the DEGs were closely related to the functional changes of trophoblast cells. Because of the enrichment of 7 DEGs and less Q value, PI3K/AKT pathway was prominent and attracted our attention. More importantly, we confirmed that knockdown of PVT1 obviously decreased AKT phosphorylation and decreased the expression of DEGs (GDPD3, ITGAV and ITGB8) while overexpression of PVT1 promoted the AKT phosphorylation and increased the expression of DEGs (GDPD3, ITGAV and ITGB8). PVT1 was primarily distributed in the nuclear compartment and also distributed in the cytoplasmic of HTR-8/Svneo cells.

CONCLUSIONS

This study provided the evidence that PVT1 played a vital role in trophoblast cells, and it is important for maintaining the normal physiological function of trophoblast cells. The PVT1 expression was lower in the GDM and PE placentas than the normal placentas, which might disrupt the function of trophoblast cells through PI3K/AKT pathway.

Knockdown of long noncoding RNA PVT1 suppresses cell proliferation and invasion of colorectal cancer via upregulation of microRNA-214-3p

Long noncoding RNAs (lncRNAs) have been reported to be involved in the occurrence and tumorigenesis of numerous malignant cancers. Microarray expression profiles were used to screen colorectal cancer (CRC)-related differentially expressed genes and lncRNAs, which revealed that insulin receptor substrate 1 (IRS1) and lncRNA plasmacytoma variant translocation 1 (PVT1) were highly expressed in CRC. This study aimed to investigate the regulatory role of lncRNA PVT1 in CRC. Subcellular localization detected by fluorescence in situ hybridization identified that lncRNA PVT1 was primarily located in the cytoplasm. The interaction between lncRNA PVT1 and microRNA-214-3p (miR-214-3p) and IRS1 was predicted using the RNA22 website. Next the dual luciferase reporter gene assay, RNA pull-down, and RNA immunoprecipitation assays verified lncRNA PVT1 to be a competitive endogenous RNA (ceRNA) against miR-214-3p, and IRS1 was found to be a target of miR-214-3p. The expression pattern of lncRNA PVT1, miR-214-3p, IRS1, phosphoinositide 3-kinase (PI3K), and Akt was characterized in response to lncRNA PVT1 silencing or miR-214-3p upregulation. Meanwhile, their regulatory effects on cell proliferation, invasion, and apoptosis were detected in CRC cells. With increased levels of miR-214-3p and decreased levels of lncRNA PVT1 in CRC cells, the expression of phosphatidylinositol 3-kinase, putative (PI3K) and Akt was reduced, and consequently, the cell apoptosis was stimulated and cell proliferation and invasion were suppressed. All in all, lncRNA PVT1 competitively binds to miR-214-3p to upregulate the expression of IRS1 thus activating the PI3K/Akt signaling pathway, thus accelerating CRC progression. This study suggests that lncRNA PVT1 might be a potential target of therapeutic strategies for CRC treatment.NEW & NOTEWORTHY This study mainly suggests that long noncoding (lnc)RNA plasmacytoma variant translocation 1 (PVT1) is a downregulated lncRNA in colorectal cancer (CRC), accelerating CRC progression. Strikingly, lncRNA PVT1 acts as a competitive endogenous RNA against microRNA (miR)-214-3p, whereas miR-214-3p targets insulin receptor substrate 1, which draws a comprehensive picture of the potential molecular mechanisms of lncRNA PVT1 in CRC.

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.

Multiple Roles of Exosomal Long Noncoding RNAs in Cancers

Long noncoding RNAs (lncRNAs) are not transcriptional noise, as previously understood, but are currently considered to be multifunctional. Exosomes are derived from the internal multivesicular compartment and are extracellular vesicles (EVs) with diameters of 30–100 nm. Exosomes play significant roles in the intercellular exchange of information and material. Exosomal lncRNAs may be promising biomarkers for cancer diagnosis and potential targets for cancer therapies, since they are increasingly understood to be involved in tumorigenesis, tumor angiogenesis, and chemoresistance. This review mainly focuses on the roles of emerging exosomal lncRNAs in cancer. In addition, the biogenesis of exosomes, the functions of lncRNAs, and the mechanisms of lncRNAs in exosome-mediated cell-cell communication are also summarized.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

Investigating the diagnostic performance of HOTTIP, PVT1, and UCA1 long noncoding RNAs as a predictive panel for the screening of colorectal cancer patients with lymph node metastasis

Like other noncoding RNAs (ncRNAs), dysregulation of long ncRNAs (lncRNAs) has been associated with various clinicopathological features of colorectal cancer (CRC) patients such as lymph node metastasis (LNM). Recently, three aberrant expressed oncogenic lncRNA (onco-lncRNAs), including HOXA transcript at the distal tip (HOTTIP), plasmacytoma variant translocation 1 (PVT1), and urothelial carcinoma associated 1 (UCA1) have been reported in LNM. Herein, we compared the diagnostic performance of these lncRNAs as individual biomarkers and as a discriminating panel between LNM CRC patients, nonmetastatic lymph nodes (NLN) and normal healthy subjects. The lncRNAs expression level was measured by quantitative real-time PCR and analyzed by the Mann-Whitney U test. The receiver operating characteristic (ROC) curve analysis was applied to evaluate the diagnostic power. The Kaplan-Meier survival analysis was performed to outline the overall survival (OS) of CRC patients with an abnormal level of lncRNAs. The area under the ROC curve (AUC) of the overexpressed HOTTIP (0.7817; 95% CI, 0.6809-0.8824), PVT1 (0.8559; 95% CI, 0.7737-0.9382), and UCA1 (0.8135; 95% CI, 0.722-0.9051) introduced them as individual CRC biomarkers. As a predictive panel, the AUC values of the HOTTIP, PVT1, and UCA1 for training set were 0.9256 (95% CI, 0.8634-0.9879; all CRCs), 0.8708 (95% CI, 0.7709-0.9378; NLN) and 0.9804 (95% CI, 0.9585-0.9998; LNM), and for validation set were 0.9286 (95% CI, 0.8752-0.9820; all CRCs), 0.8911 (95% CI, 0.8238-0.9585; NLN), and 0.9833 (95% CI, 0.9642-1.002; LNM), respectively. Also, HOTTIP/PVT1/UCA1 panel dysregulation had a marked correlation with patient's OS in training set (logrank test P = 0.0121; hazard ratio [HR], 0.1225; 95% confidence interval [CI], 0.02376-0.6312), and in validation set (logrank test P < 0.0001, HR, 0.2003; 95% CI, 0.08942-0.4486). These data showed that the combination of HOTTIP, PVT1, and UCA1 as a predictive panel, has a better diagnostic performance than each of these lncRNAs individually, and could be used for the screening of patients with advanced CRC.

LncRNA PVT1 promotes proliferation, invasion and epithelial-mesenchymal transition of renal cell carcinoma cells through downregulation of miR-16-5p

Background

LncRNAs have recently emerged as vital regulators in the pathogenesis and development of various cancers. LncRNA PVT1 is reported to function as an oncogene in some tumors. However, the role of PVT1 in RCC remains unknown.

Purpose

To explore the potential effects of lncPVT1 on the development of renal cell carcinoma.

Methods

The expression of PVT1 in renal cancer cell lines and tissues was measured by qRT-PCR. The endogenous PVT1 was silenced by RNAi. Cell viabilities were measured by the MTT assay. The migration and invasion of cells were investigated by the transwell assay. The apoptosis of cells was measured by the Nucleosome ELISA and caspase-3 activity assays. The levels of proteins were measured by the western blot.

Results

We found that PVT1 was upregulated in RCC tissues compared with the adjacent normal tissues. PVT1 expression was closely correlated with TNM stage, Fuhrman grade, lymph node metastasis and tumor size. Kaplan–Meier analysis revealed that high expression of PVT1 was significantly associated with poor overall survival. In accordance, overexpression of PVT1 was observed in RCC cells comto HK-2 cell. Silencing of PVT1 significantly repressed cell viability, induced apoptosis and inhibited cell migration and invasion in vitro. Furthermore, bioinformatic analysis and luciferase reporter assay confirmed that miR-16-5p was a target of PVT1. Silencing of miR-16-5p mostly reversed the regulatory effects on RCC cells induced by downregulation of PVT1.

Conclusion

In summary, our study indicates that targeting PVT1 might represent a rational therapeutic strategy for RCC.

Linc01194 acts as an oncogene in colorectal carcinoma and is associated with poor survival outcome

Background

The incidence of colorectal cancer ranks among the top three malignant tumors, attributing to more than 50,000 deaths in the United States every year. Survival rate is directly correlated with TNM stage at diagnosis, and identifying the molecules involved in the cancer development process will provide directions to better investigate the mechanisms of colorectal cancer.

Materials and methods

Bioinformatics analysis of differentially expressed long noncoding RNAs (lncRNAs), survival analysis, cell proliferation assay, migration assay, and Western blot analysis were performed.

Results

Fifty-one lncRNAs were identified between the early stage and late-stage groups. In the survival analysis, we found that Linc01194 is correlated with poor survival of colon cancer patients. In addition, by suppressing the expression of Linc01194 in colon cancer cell lines, cell proliferation and migration were inhibited. Western blot showed that N-cadherin and vimentin were downregulated, whereas E-cadherin was upregulated indicating that the process of epithelial–mesenchymal transition (EMT) was restrained.

Conclusion

Linc01194 promotes the proliferation and migration ability of colon cancer cells by activating EMT. It acts as an oncogene in colorectal carcinoma and is associated with worse survival outcome.

PVT1 (rs13281615) and miR-146a (rs2910164) polymorphisms affect the prognosis of colon cancer by regulating COX2 expression and cell apoptosis

In this study, we aimed to investigate the potential correlation between rs13281615/rs2910164 polymorphisms and the prognosis of colon cancer (CC). Taqman was utilized to genotype the rs13281615/rs2910164 polymorphisms in recruited subjects. Kaplan-Meier survival curves were calculated to study the prognostic values of different genotypes of rs13281615/rs2910164 polymorphisms. Real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunohistochemistry, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assays were conducted to establish a potential signaling pathway underlying the role of rs13281615/rs2910164 polymorphisms, whereas bioinformatics analysis and luciferase reporter assays were performed to identify plasmacytoma variant translocation 1 (PVT1) and cyclooxygenase-2 (COX2) as targets of microRNA-146a (miR-146a). No significant difference was observed in respect to clinical characteristics among subjects with different genotypes. However, patients genotyped as GG/CC + GC showed the lowest chance of survival, whereas patients of GA + AA/GG genotype showed the highest chance of survival. Moreover, the relative expressions of PVT1, prostaglandin E2 (PGE2), and COX2 were the lowest and the relative expression of miR-146a was the highest in GA + AA/GG subjects, validating the roles of PVT1, miR-146a, and COX2 in CC. In addition, both PVT1 and COX2 were identified as virtual targets of miR-146a, and the luciferase activities of cells cotransfected with wild-type PVT1/COX2 and miR-146a mimics were significantly reduced. Moreover, the presence of PVT1 decreased the level of miR-146a whereas increasing the messenger RNA and protein levels of COX2, thus establishing a PVT1/miR-146a/COX2 signaling pathway underlying the pathogenesis of CC. The presence of rs13281615 G > A polymorphism on PVT1 and the rs2910164 C > G polymorphism on miR-146a contributes to a favorable prognosis in CC patients via modulating the activity of the PVT1/miR-146a/COX2 signaling pathway.

Long noncoding RNA PVT1: potential oncogene in the development of acute lymphoblastic leukemia

Emerging evidence shows that long noncoding RNAs (lncRNAs) participate in various cellular processes, and that plasmacytoma variant translocation 1 (PVT1), a newly described oncogene that interacts with various molecules such as p15, p16, NOP2, and c-Myc, is a major contributing factor in tumor development. However, the role of this oncogene remains unknown in the pathogenesis of acute lymphoblastic leukemia (ALL), the most prevalent form of childhood leukemia. In this study, we first measure the expression level of PVT1 in a Jurkat cell line, then small interfering (siRNA) PVT1 is applied to demonstrate the impact of PVT1 knockdown in apoptosis, proliferation, the cell cycle, and its downstream targets. Our findings show that lncRNA was significantly higher in the ALL cell line than normal lymphocytes and that PVT1 knock-down increased the rate of apoptosis, caused G0/G1 arrest in the cell cycle, reduced the proliferation rate, and, above all, reduced the stability of c-Myc protein. All findings were confirmed at the molecular level. Our results may indicate the role of PVT1 knock-down in the suppression of ALL development and might provide an option for targeted therapy for leukemic conditions.

Non-Coding RNA Pvt1 Promotes Cancer Stem Cell-Like Traits in Nasopharyngeal Cancer via Inhibiting miR-1207

Nasopharyngeal carcinoma (NPC) is a kind of head-neck malignant tumor. lncRNA-PVT1 can promote the proliferation of carcinoma cells, and induce cells to have stem cell-like potentials. However, the function of PVT1 in NPC cells is not clear. The expressions of lncRNA-PVT1 and the expressions of the stem cell markers in NPC tissues or cell lines were investigated by qRT-PCR or western blot. The cell proliferation, and the ability of NPC cells to form spherical, clonal colonies were investigated by MTT assay, colony formation assay, and tumor-sphere formation assay. Cancer stem cells surface markers were detected by flow cytometry and western blot. PI3K/AKT signal activation in NPC cells was determined by western blot. PVT1 was significantly up-regulated in both NPC tissues and cell lines and associated with poor prognosis. PVT1 knockdown reduced NPC cells viability, clonogenicity, the cell surface CD44+/CD24- stem phenotype, and the expressions of the stem cell markers in NPC cells, including Oct4, c-Myc, SOX2, and ALDH. Furthermore, PVT1 negatively regulates the expression levels of miR-1207 in NPC cells and spheres cells, which is critical for NPC stemness. Knockdown of miR-1207 promoted stem phenotype and the expressions of the stem cell markers in NPC cells. Moreover, phosphor-PI3K (p-PI3K) and phosphor-AKT (p-AKT) were found to be down-regulated after PVT1 siRNAs transfection in NPC cells. And miR-1207 inhibitor transfection reversed the all the effects brought by PVT1 knockdown. Pvt1 promotes cancer stem cell-like properties in NPC cells via inhibiting miR-1207 and activating the PI3K/AKT signal pathway.

Long Noncoding RNA PVT1 as a Novel Predictor of Metastasis, Clinicopathological Characteristics and Prognosis in Human Cancers: a Meta-Analysis

The present meta-analysis aimed to systematically evaluates the metastasis, clinical stage, and prognostic value regarding the expression levels of PVT1 in various cancers. Relevant literatures were searched in PubMed、Cochrane Library、Wed of science、Embase databases、Chinese National Knowledge Infrastructure and Wanfang from inception up to 22 August 2017. After data were extracted, a meta-analysis was performed using Review Manager 5.3 and Stata 12.0 software. The meta-analysis showed that high expression of PVT1 could predict more lymph node metastasis (LNM) (Odds ratio, OR = 2.83, 95% confidence interval, CI: 1.76–4.54, P < 0.0001), distant metastasis (DM) (OR = 3.60, 95% CI: 1.08–12.03, P = 0.04), advanced clinical stage (OR = 4.37, 95% CI: 3.45–5.54, P < 0.00001) and poor overall survival (Hazard ratio, HR = 2.08, 95% CI: 1.82–2.37, P < 0.00001)in cancer. Subgroup analysis in different systems also showed the same results, including respiratory system、digestive system、urinary system and other systems, especially in respiratory system (LNM, OR = 4.57, 95% CI: 2.41–8.68, P < 0.00001; clinical stage, OR = 5.59, 95% CI: 3.59–8.71, P < 0.00001; OS, HR = 2.43, 95% CI: 1.98–2.99, P < 0.00001). These results suggest that PVT1 could serve as a novel biomarker for metastasis, clinical stage and poor prognosis in various tumors.

Long noncoding RNA PVT1-214 promotes proliferation and invasion of colorectal cancer by stabilizing Lin28 and interacting with miR-128

Long noncoding RNAs (lncRNAs) are implicated in human cancer, but their mechanisms of action are largely unknown. In this study, we investigated lncRNA alterations that contribute to colorectal cancer (CRC) through microarray expression profiling in CRC patient samples. Here, we report that the CRC-associated lncRNA PVT1-214 is a key regulator of CRC development and progression; patients with high PVT1-214 expression had a shorter survival and poorer prognosis. In vitro and in vivo investigation of the role of PVT1-214 revealed a complex integrated phenotype affecting cell growth, stem-like properties, migration, and invasion. Furthermore, using RNA pull-down and mass spectrometry, we found that Lin28 (also known as Lin28A), a highly conserved RNA-binding protein, is associated with PVT1-214. Strikingly, we found that PVT1-214 not only upregulated Lin28 protein expression in CRC cells by stabilizing Lin28, but also participated in crosstalk with Lin28 mRNA through competition for miR-128 binding, imposing an additional level of post-transcriptional regulation. In addition, we further show that PVT1-214 repressed expression of let-7 family miRNAs, which was abrogated by Lin28 knockdown. Taken together, our findings support a model in which the PVT1-214/Lin28/let-7 axis serves as a critical regulator of CRC pathogenesis, which may simulate a new direction for CRC therapeutic development.

Long Noncoding RNAs in Colorectal Adenocarcinoma; an in silico Analysis

Long noncoding RNAs (lncRNAs) are lengthy noncoding transcripts which are involved in critical signaling pathways including cell cycle and apoptosis so it is not surprising to see their altered expression in human tumors. Colorectal adenocarcinoma is one the most frequent malignancies worldwide. The role of lncRNAs in colorectal adenocarcinoma is not well understood. To study the significance of lncRNAs in colorectal adenocarcinoma, we retrieved 189 approved lncRNAs from HGNC. The genes were imported into the cBioPortal database for transcriptomic analyses. We queried all the samples from TCGA provisional colorectal adenocarcinoma with RNA-seq v2 data in our study and considered RNA dysregulation with Z-score: ±2. The lncRNA which was altered in most of the patients were considered as "significant lncRNA" for further analyses. We considered the association of candidate lncRNAs with clinicopathologic parameters of samples including tumor disease anatomic site, neoplasm histologic types, tumor stage and survival. We also compute the specificity of the significant lncRNAs expression in colorectal adenocarcinoma comparing with other human cancers in cancer portal. Our analysis showed that lncRNAs SNHG6, PVT1 and ZFAS1 allocated the maximum alteration among the colorectal cases. The expression of SNHG6 and ZFAS1 was more in rectal adenocarcinoma than the colon carcinoma while the PVT1 showed the same expression levels in both tissues. However, we found that upregulation of PVT1 has been reduced the overall survival in patients. Altogether these data showed SNHG6, PVT1 and ZFAS1, are promising candidates for experimental research on colorectal adenocarcinoma to discover novel biomarker for this prevalent cancer.

Long non-coding RNA PVT1 as a novel potential biomarker for predicting the prognosis of colorectal cancer

BACKGROUND

Long non-coding RNA (lncRNA) plays a very important role in the occurrence and development of various tumors, and is a potential biomarker for cancer diagnosis and prognosis. The purpose of this study was to investigate the relationship between the expression of lncRNA plasmacytoma variant translocation 1 (PVT1) and the prognostic significance in patients with colorectal cancer.

METHODS

The expression of PVT1 was measured by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in cancerous and adjacent tissues of 210 colorectal cancer patients. The disease-free survival and overall survival of colorectal cancer patients were evaluated by Kaplan-Meier analysis, and univariate and multivariate analysis were performed by Cox proportional-hazards model.

RESULTS

Our results revealed that PVT1 expression in cancer tissues of colorectal cancer was significantly higher than that of adjacent tissues (P<0.001). High PVT1 expression was increased by 51.4% (108/210), which was significantly correlated with the tumor differentiation, the depth of invasion, the stage of tumor, node, metastasis (TNM), and lymphatic metastasis. The Kaplan-Meier analysis showed that high PVT1 expression resulted in a shorter disease-free survival (Log-rank test P<0.001) and overall survival (Log-rank test P<0.001) compared with the low PVT1 expression group in colorectal cancer patients, whether at TNM I/II stage or at TNM III/IV stage. A multivariate Cox regression analysis demonstrated that high PVT1 expression was an independent predictor of poor prognosis in colorectal cancer patients.

CONCLUSIONS

Our results suggest that high PVT1 expression might be a potential biomarker for assessing tumor recurrence and prognosis in colorectal cancer patients.

Long non-coding RNAs: crucial regulators of gastrointestinal cancer cell proliferation

Studies of long non-coding RNAs (lncRNAs) have been prevalent in the field of non-coding RNA regulation in recent years. LncRNAs exert crucial effects on malignant cell processes in the gastrointestinal system, including proliferation. Aberrant lncRNA expression, through both oncogenes and tumor suppressor genes, is instrumental to tumor cell proliferation. Here, we summarize the different molecular mechanisms and relevant signaling pathways through which multifarious lncRNAs regulate cell proliferation and we show that lncRNAs are potential biomarkers for gastrointestinal cancers.

Construction of a ceRNA network reveals potential lncRNA biomarkers in rectal adenocarcinoma

Competing endogenous RNAs (ceRNAs) render the functions of long non-coding RNAs (lncRNAs) more complicated during cancer processes. Potential lncRNA biomarkers and their roles as ceRNAs have not been clearly described for rectal adenocarcinoma (READ). In the present study, we extracted data from The Cancer Genome Atlas (TCGA) including data from 167 tumor samples and 10 adjacent non-tumor samples. A total of 202 lncRNAs, 190 microRNAs (miRNAs) and 1,530 mRNAs were identified as READ-specific RNAs [log₂(fold-change)>2, FDR<0.01]. The Gene Ontology (GO) biological processes and the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways were analysed for 1,530 specific mRNAs. Among 202 READ-specific lncRNAs, 7 lncRNAs were identified as being associated with overall survival of READ patients. Then, a ceRNA network was constructed with 34 key lncRNAs, 25 miRNAs and 65 mRNAs. A total of 7 lncRNAs from the network were revealed to be linked to clinical features. The results of qRT-PCR ascertained that our analysis was credible. Overall, this research provides a novel perspective from which to study the lncRNA-related ceRNA network in READ and assists in the identification of new potential biomarkers to be used for diagnostic and prognostic purposes.

Upregulated plasmacytoma variant translocation 1 promotes cell proliferation, invasion and metastasis in colorectal cancer

Emerging evidence indicates that the long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) is associated with tumourigenesis in various types of cancer. However, its specific effects on the proliferation, invasion and metastasis of colorectal cancer (CRC) are still poorly understood. The present study aimed to investigate PVT1 expression in CRC and explore its role in CRC pathogenesis. The reverse transcriptase‑quantitative polymerase chain reaction (RT‑qPCR) technique was used to assess PVT1 expression in CRC cell lines. Gene Expression Omnibus (GEO) database analysis and measurement of clinical samples was used to analyse the correlation between PVT1 expression, CRC metastasis and overall survival (OS). In addition, knockdown of PVT1 expression was performed using short interfering RNA (siRNA) and RT‑qPCR, western blotting, CCK‑8 assays, tumour cell clone‑formation and Matrigel invasion assays were used to observe its biological functions in HCT116 cells. The present study demonstrated that the expression of PVT1 in CRC cell lines was higher than that in normal colon mucosal cell lines. Using GEO database analysis and the measurement of clinical samples, it was revealed that CRC patients with high PVT1 expression demonstrated poor OS. Multivariate analysis indicated that high PVT1 expression is an independent risk factor for patients with CRC. In addition, PVT1 knockdown suppressed the proliferation, invasion and metastasis of CRC cells in vitro, which were associated with decreasing vimentin, cyclin D1 and cyclin‑dependent kinase 4 expression and enhanced E‑cadherin expression. The results of the present study suggest that PVT1 may serve a critical role in CRC progression and metastasis and may serve as a potential prognostic biomarker for CRC.

A comprehensive genome-wide analysis of long noncoding RNA expression profile in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, especially in East Asia and China. Long noncoding RNAs (lncRNAs) are emerging as critical regulators that may be involved in the development and progression of cancers in humans. However, the contributions of lncRNAs to HCC development, metastasis, and recurrence remain largely unknown. In this study, we comprehensively investigated lncRNA expression profile in HCC and normal tissues using TCGA RNA sequencing data, one RNA sequencing dataset, and two microarray datasets from GEO. By analyzing these four datasets, we identified hundreds of expression-dysregulated lncRNAs in HCC tissues compared with normal tissues. Genomic copy number variation analysis showed that many of those lncRNAs disorder are related to the copy number amplification or deletion. Moreover, several lncRNAs expression levels are associated with HCC patients' overall and recurrence-free survival, such as RP1-228H13.5, TMCC1-AS1, LINC00205, and RP11-307C12.11. Furthermore, we identified two lncRNAs termed PVT1 and SNHG7 that may be involved in HCC cells metastasis by comparing lncRNAs expression profiles between early recurrence HCC tissues with metastasis and late recurrence HCC tissues without metastasis. Finally, loss-of-function assays confirmed that knockdown of SNHG7 and PVT1 impaired HCC cells invasion. Taken together, these findings may provide a valuable resource for further identification of novel biomarkers and therapeutic targets for HCC patients.

LncRNA PVT1 predicts prognosis and regulates tumor growth in prostate cancer

Long non-coding RNA (lncRNA) plasmacytoma variant translocation 1(PVT1) was aberrantly expressed in various cancers and is associated with tumor prognosis. Here, we aim to investigate its function in prostate cancer. Small interfering RNA against PVT1 was transfected into prostate cancer cell lines and cell growth and apoptosis were analyzed. Our results showed that PVT1 was overexpressed in prostate cancer tissues and cells. Higher levels of PVT1 indicated poorer overall survival and disease-free survival. A significant association was found between PVT1 expression and tumor stage. Besides, PVT1 knockdown significantly inhibited prostate cancer growth in vivo and in vitro and promoted cell apoptosis. PVT1 knockdown also significantly upregulated the expression of cleaved caspase-3 and cleaved caspase-9, but downregulated the expression of c-Myc in prostate cancer cell lines. Our results suggest that PVT1 played an oncogenic role in prostate cancer and could be used as a potential biomarker for diagnosis of prostate cancer.

Long non-coding RNA PVT1: Emerging biomarker in digestive system cancer

The digestive system cancers are leading cause of cancer-related death worldwide, and have high risks of morbidity and mortality. More and more long non-coding RNAs (lncRNAs) have been studied to be abnormally expressed in cancers and play a key role in the process of digestive system tumour progression. Plasmacytoma variant translocation 1 (PVT1) seems fairly novel. Since 1984, PVT1 was identified to be an activator of MYC in mice. Its role in human tumour initiation and progression has long been a subject of interest. The expression of PVT1 is elevated in digestive system cancers and correlates with poor prognosis. In this review, we illustrate the various functions of PVT1 during the different stages in the complex process of digestive system tumours (including oesophageal cancer, gastric cancer, colorectal cancer, hepatocellular carcinoma and pancreatic cancer). The growing evidence shows the involvement of PVT1 in both proliferation and differentiation process in addition to its involvement in epithelial to mesenchymal transition (EMT). These findings lead us to conclude that PVT1 promotes proliferation, survival, invasion, metastasis and drug resistance in digestive system cancer cells. We will also discuss PVT1's potential in diagnosis and treatment target of digestive system cancer. There was a great probability PVT1 could be a novel biomarker in screening tumours, prognosis biomarkers and future targeted therapy to improve the survival rate in cancer patients.

lncRNAs PVT1 and HAR1A are prognosis biomarkers and indicate therapy outcome for diffuse glioma patients

Diffuse gliomas are well known malignant brain tumors. Long non-coding RNAs (lncRNAs), a type of RNA transcript with more than 200 nucleotides, involve in tumorigenesis and development of various cancers. This study focused on identifying differentially expressed lncRNAs in gliomas based on gene expression profiling, and chose certain lncRNAs PVT1, CYTOR, HAR1A and MIAT, which changed with significant differences. Further analysis of TCGA and GEO data revealed that the expressions of PVT1 and CYTOR were up-regulated, while HAR1A and MIAT expressions were down-regulated in gliomas. Their expression patterns were validated in an independent cohort containing 98 glioma specimens and 12 non-tumor tissue controls. High expression of PVT1 and CYTOR as well as low HAR1A and MIAT expression were associated with high Ki-67 level and more TP53 mutation. Kaplan-Meier survival curve and Cox regression analyses showed that glioma patients with high PVT1 expression or low HAR1A expression had poor survival outcome, aberrantly expressed PVT1 and HAR1A could be the independent prognosis biomarkers for glioma patients. Moreover, down-regulation of PVT1 and up-regulation of HAR1A contributed to improve the survival of patients who received chemotherapy and radiotherapy. These results implied that these four lncRNAs might play important role in diffuse gliomas progression, particularly, PVT1 and HAR1A could be explored as promising biomarkers for diagnosis, prognosis and target therapy of diffuse gliomas.

Colon cancer associated transcripts in human cancers

Long non-coding RNAs serve as important regulators in complicated cellular activities, including cell differentiation, proliferation and death. Dysregulation of long non-coding RNAs occurs in the formation and progression of cancers. The family of colon cancer associated transcripts, long non-coding RNAs colon cancer associated transcript-1 and colon cancer associated transcript-2 are known as oncogenes involved in various cancers. Colon cancer associated transcript-1 is a novel lncRNA located in 8q24.2, and colon cancer associated transcript-2 maps to the 8q24.21 region encompassing rs6983267. Colon cancer associated transcripts have close associations with clinical characteristics, such as lymph node metastasis, high TNM stage and short overall survival. Knockdown of them can reverse the malignant phenotypes of cancer cells, including proliferation, migration, invasion and apoptosis. Moreover, they can increase the expression level of c-MYC and oncogenic microRNAs via activating a series of complex mechanisms. In brief, the family of colon cancer associated transcripts may serve as potential biomarkers or therapeutic targets for human cancers.