Long non-coding RNA NEAT1 is a transcriptional target of p53 and modulates p53-induced transactivation and tumor-suppressor function

Emerging Roles of p53 Related lncRNAs in Cancer Progression: A Systematic Review

p53 is the major mediator of the tumor suppressor response. It participates in apoptosis and senescence and can respond to DNA damage. As a crucial sequence-specific transcription factor, p53 regulates the expression of many genes, such as small noncoding RNAs (ncRNAs), microRNAs, and long ncRNAs (lncRNAs). Given the emergence of novel and high-throughput sequencing technologies, many lncRNAs have been discovered. LncRNAs may function as vital gene regulators in a variety of biological processes through extensive mechanisms. Recently, lncRNAs have been demonstrated to be associated with the p53 regulatory pathway. In this review, we discuss the current and fast growing knowledge about the influence of lncRNAs to the p53 signaling pathway, the different mechanisms by which they affect gene expression in cancer. Our findings show that p53-associated lncRNAs may be used as biomarkers for cancer diagnosis or targets for disease therapy.

Modulation of cancer cell signaling by long noncoding RNAs

Cellular signaling pathways play a very important role in almost all molecular processes in the cell, and are generally composed of a complex set of cascades in which enzymes and proteins play a key role. These signaling pathways include different types of cellular signaling classified based on their receptors and effector proteins such as enzyme-linked receptors, cytokine receptors, and G-protein-coupled receptors each of which is subdivided into different classes. Signaling pathways are tightly controlled by different mechanisms mostly thorough inhibiting/activating their receptors or effector proteins. In the last two decades, our knowledge of molecular biology has changed dramatically and today we know that more than 85% of the human genome expresses noncoding RNAs most of which are crucial in the cellular and molecular mechanisms of cells. One of these noncoding RNAs are long noncoding RNAs (lncRNA) containing more than 200 nucleotides. LncRNAs participate in the progression of cancer growth through several mechanism including signaling pathways. In this review, we summarize some of the most important of lncRNAs and their effect on important signaling pathways.

Prognostic Effect of Long Noncoding RNA NEAT1 Expression Depends on p53 Mutation Status in Cancer

Recently, many studies have revealed that long noncoding RNAs (lncRNAs) play important roles in various biological and pathological processes. Our previous study reported that lncRNA NEAT1 is a direct transcriptional target of p53. NEAT1 is an essential component of paraspeckles, which have recently been identified as a novel type of nuclear compartment. Although our previous findings indicate that NEAT1 induction contributes to the tumor-suppressor function of p53, the role of NEAT1 in cancer is still controversial. In this study, we comprehensively analyzed the relationship between NEAT1 expression and p53 mutation status. Interestingly, survival analysis based on NEAT1 expression in several cancer tissues revealed that the p53 wild-type group with high NEAT1 expression had a good prognosis, while poor prognosis or no correlation between NEAT1 expression and survival was observed in the p53-mutated group. These results demonstrate that the tumor-suppressive effect of NEAT1 depends on p53 function and is consistent with our previous report showing that NEAT1 supports the tumor-suppressive function of p53. Specifically, NEAT1 seems to play a tumor-suppressive role only in the presence of wild-type p53. These results provide important clues to the roles of NEAT1 in cancer.

Long non-coding RNA NEAT1 confers oncogenic role in triple-negative breast cancer through modulating chemoresistance and cancer stemness

Triple-negative breast cancer (TNBC) is a malignant subtype of breast cancer with the absence of targeted therapy, resulting in poor prognosis in patients. Chemotherapy remains the mainstay of treatment for TNBC; however, development of drug resistance is the main obstacle for successful treatments. In recent years, long non-coding RNA (lncRNA) has been implicated in multiple biological functions in various diseases, particularly cancers. Accumulating evidence suggested that lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) expression is dysregulated in many human cancers and thus is a useful prognostic marker for cancer patients. Nevertheless, the mechanism of how NEAT1 confers drug resistance in TNBC is still largely unknown. We performed lncRNA profiling by the LncRNA Profiler qPCR Array Kit in normal control (NC) and breast cancers (BC) blood samples and further validated in a larger cohort of samples by qRT-PCR. Gene expression level and localization were investigated by qRT-PCR, western blotting, and immunofluorescence staining. Flow cytometric analysis was carried out to detect cancer stem cells. Functional studies were performed both in vitro and in vivo xenograft model. Among 90 lncRNAs, NEAT1 was highly expressed in the blood samples of breast cancer patients than in NC. In particular, the expression of NEAT1 was higher in TNBC tissues than other subgroups. Functional studies revealed that NEAT1 conferred oncogenic role by regulating apoptosis and cell cycle progression in TNBC cells. We identified that knockdown of NEAT1 sensitized cells to chemotherapy, indicating the involvement in chemoresistance. Importantly, shNEAT1 reduced stem cell populations such as CD44+/CD24−, ALDH+, and SOX2+, implicating that NEAT1 was closely related to cancer stemness in TNBC. Our data highlighted the roles of NEAT1 chemoresistance and cancer stemness, suggesting that it could be used as a new clinical therapeutic target for treating TNBC patients especially those with drug resistance.

The long non-coding RNA NEAT1 is elevated in polyglutamine repeat expansion diseases and protects from disease gene-dependent toxicities

Polyglutamine (polyQ) repeat diseases are a class of neurodegenerative disorders caused by CAG-repeat expansion. There are diverse cellular mechanisms behind the pathogenesis of polyQ disorders, including transcriptional dysregulation. Interestingly, we find that levels of the long isoform of nuclear paraspeckle assembly transcript 1 (Neat1L) are elevated in the brains of mouse models of spinocerebellar ataxia types 1, 2, 7 and Huntington's disease (HD). Neat1L was also elevated in differentiated striatal neurons derived from HD knock-in mice and in HD patient brains. The elevation was mutant Huntingtin (mHTT) dependent, as knockdown of mHTT in vitro and in vivo restored Neat1L to normal levels. In additional studies, we found that Neat1L is repressed by methyl CpG binding protein 2 (MeCP2) by RNA-protein interaction but not by occupancy of MeCP2 at its promoter. We also found that NEAT1L overexpression protects from mHTT-induced cytotoxicity, while reducing it enhanced mHTT-dependent toxicity. Gene set enrichment analysis of previously published RNA sequencing data from mouse embryonic fibroblasts and cells derived from HD patients shows that loss of NEAT1L impairs multiple cellular functions, including pathways involved in cell proliferation and development. Intriguingly, the genes dysregulated in HD human brain samples overlap with pathways affected by a reduction in NEAT1, confirming the correlation of NEAT1L and HD-induced perturbations. Cumulatively, the role of NEAT1L in polyQ disease model systems and human tissues suggests that it may play a protective role in CAG-repeat expansion diseases.

Involvement of the long noncoding RNA NEAT1 in carcinogenesis

Altered expression levels of the long noncoding RNA (lncRNA) nuclear‐enriched abundant transcript 1 (NEAT1) have been reported in different types of cancer. More than half of the NEAT1 studies in cancer have been published within the last 2 years. In this review, we discuss very recent developments and insights into NEAT1 contribution to carcinogenesis. Summarizing the literature, it becomes obvious that NEAT1 is a lncRNA highly de‐/upregulated in a variety of cancer entities, in which it primarily acts as a competing endogenous RNA (ceRNA) which sponges tumor‐suppressive microRNA (miRNA). The sponged miRNA lose their ability to degrade, silence, or hamper translation of their downstream—mostly oncogenic—target transcripts, ultimately promoting carcinogenesis. This role of NEAT1 function in tumorigenesis suggests it may be a prognostic biomarker as well as potential therapeutic target, pending the completion of further studies into the underlying mechanisms.

PTBP3 splicing factor promotes hepatocellular carcinoma by destroying the splicing balance of NEAT1 and pre-miR-612

Nuclear-enriched RNA-binding proteins (RBPs) are mainly involved in transcriptional regulation, which is a critical checkpoint to tune gene diversity and expression levels. We analyzed nuclear RBPs in human HCC tissues and matched normal control tissues. Based on the gene expression levels, PTBP3 was identified as top-ranked in the nuclei of HCC cells. HCC cell lines then were transfected with siRNAs or lentiviral vectors. PTBP3 promoted HCC cell proliferation and metastasis both in vitro and in vivo. RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH) and qRT-PCR assays verified that PTBP3 protein recruited abundant lnc-NEAT1 splicing variants (NEAT1_1 and NEAT1_2) and pre-miR-612 (precursor of miR-612) in the nucleus. NEAT1_1, NEAT1_2 and miR-612 expression levels were determined by PTBP3. Correlational analyses revealed that PTBP3 was positively correlated with NEAT1, but it was inversely correlated with miR-612 in HCC. The P53/CCND1 and AKT2/EMT pathways were determined by NEAT1 and miR-612 respectively in HCC. The PTBP3^high and NEAT1^high/miR-612^low patients had a shorter overall survival. Therefore, nuclear-enriched RBP, PTBP3, promotes HCC cell malignant growth and metastasis by regulating the balance of splicing variants (NEAT1_1, NEAT1_2 and miR-612) in HCC.

The regulatory roles of lncRNAs in the process of breast cancer invasion and metastasis

Breast cancer (BC) is the most common cancer and principal cause of death among females worldwide. Invasion and metastasis are major causes which influence the survival and prognosis of BC. Therefore, to understand the molecule mechanism underlying invasion and metastasis is paramount for developing strategies to improve survival and prognosis in BC patients. Recent studies have reported that long non-coding RNAs (lncRNAs) play critical roles in the regulation of BC invasion and metastasis through a variety of molecule mechanisms that endow cells with an aggressive phenotype. In this article, we focused on the function of lncRNAs on BC invasion and metastasis through participating in epithelial-to-mesenchymal transition, strengthening cancer stem cells generation, serving as competing endogenous lncRNAs, influencing multiple signaling pathways as well as regulating expressions of invasion-metastasis related factors, including cells adhesion molecules, extracellular matrix, and matrix metallo-proteinases. The published work described has provided a better understanding of the mechanisms underpinning the contribution of lncRNAs to BC invasion and metastasis, which may lay the foundation for the development of new strategies to prevent BC invasion and metastasis.

Altered Levels of Long NcRNAs Meg3 and Neat1 in Cell And Animal Models Of Huntington's Disease

Altered expression levels of protein-coding genes and microRNAs have been implicated in the pathogenesis of Huntington's disease (HD). The involvement of other ncRNAs, especially long ncRNAs (lncRNA), is being realized recently and the related knowledge is still rudimentary. Using small RNA sequencing and PCR arrays we observed perturbations in the levels of 12 ncRNAs in HD mouse brain, eight of which had human homologs. Of these, Meg3, Neat1, and Xist showed a consistent and significant increase in HD cell and animal models. Transient knock-down of Meg3 and Neat1 in cell models of HD led to a significant decrease of aggregates formed by mutant huntingtin and downregulation of the endogenous Tp53 expression. Understanding Meg3 and Neat1 functions in the context of HD pathogenesis is likely to open up new strategies to control the disease.

Molecular dissection of nuclear paraspeckles: towards understanding the emerging world of the RNP milieu

Paraspeckles are nuclear bodies built on an architectural long noncoding RNA, NEAT1, and a series of studies have revealed their molecular components, fine internal structures and cellular and physiological functions. Emerging lines of evidence suggest that paraspeckle formation is elicited by phase separation of associating RNA-binding proteins containing intrinsically disordered regions, which induce ordered arrangement of paraspeckle components along NEAT1. In this review, we will summarize the history of paraspeckle research over the last couple of decades, especially focusing on the function and structure of the nuclear bodies. We also discuss the future directions of research on long noncoding RNAs that form ‘RNP milieux’, large and flexible phase-separated ribonucleoprotein complexes.

The long noncoding RNA NEAT1 and nuclear paraspeckles are up-regulated by the transcription factor HSF1 in the heat shock response

The long noncoding RNA (lncRNA) NEAT1 (nuclear enriched abundant transcript 1) is the architectural component of nuclear paraspeckles, and it has recently gained considerable attention as it is abnormally expressed in pathological conditions such as cancer and neurodegenerative diseases. NEAT1 and paraspeckle formation are increased in cells upon exposure to a variety of environmental stressors and believed to play an important role in cell survival. The present study was undertaken to further investigate the role of NEAT1 in cellular stress response pathways. We show that NEAT1 is a novel target gene of heat shock transcription factor 1 (HSF1) and is up-regulated when the heat shock response pathway is activated by sulforaphane (SFN) or elevated temperature. HSF1 binds specifically to a newly identified conserved heat shock element in the NEAT1 promoter. In line with this, SFN induced the formation of NEAT1-containing paraspeckles via an HSF1-dependent mechanism. HSF1 plays a key role in the cellular response to proteotoxic stress by promoting the expression of a series of genes, including those encoding molecular chaperones. We have found that the expression of HSP70, HSP90, and HSP27 is amplified and sustained during heat shock in NEAT1-depleted cells compared with control cells, indicating that NEAT1 feeds back via an unknown mechanism to regulate HSF1 activity. This interrelationship is potentially significant in human diseases such as cancer and neurodegenerative disorders.

The lncRNA NEAT1 activates Wnt/β-catenin signaling and promotes colorectal cancer progression via interacting with DDX5

Background

The long noncoding RNA nuclear-enriched abundant transcript 1 (NEAT1) has been reported to be overexpressed in colorectal cancer (CRC). However, its underlying mechanisms in the progression of CRC have not been well studied.

Methods

To investigate the clinical significance of NEAT1, we analyzed its expression levels in a publicly available dataset and in 71 CRC samples from Fudan University Shanghai Cancer Center. Functional assays, including the CCK8, EdU, colony formation, wound healing, and Transwell assays, were used to determine the oncogenic role of NEAT1 in human CRC progression. Furthermore, RNA pull-down, mass spectrometry, RNA immunoprecipitation, and Dual-Luciferase Reporter Assays were used to determine the mechanism of NEAT1 in CRC progression. Animal experiments were used to determine the role of NEAT1 in CRC tumorigenicity and metastasis in vivo.

Results

NEAT1 expression was significantly upregulated in CRC tissues compared with its expression in normal tissues. Altered NEAT1 expression led to marked changes in proliferation, migration, and invasion of CRC cells both in vitro and in vivo. Mechanistically, we found that NEAT1 directly bound to the DDX5 protein, regulated its stability, and sequentially activated Wnt signaling. Our study showed that NEAT1 indirectly activated the Wnt/β-catenin signaling pathway via DDX5 and fulfilled its oncogenic functions in a DDX5-mediated manner. Clinically, concomitant NEAT1 and DDX5 protein levels negatively correlated with the overall survival and disease-free survival of CRC patients.

Conclusions

Our findings indicated that NEAT1 activated Wnt signaling to promote colorectal cancer progression and metastasis. The NEAT1/DDX5/Wnt/β-catenin axis could be a potential therapeutic target of pharmacological strategies.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0656-7) contains supplementary material, which is available to authorized users.

LncRNA HOXA11-AS drives cisplatin resistance of human LUAD cells via modulating miR-454-3p/Stat3

Over the past several years, long non‐coding RNAs (lncRNAs) have attracted more and more attention due to their special functions. They are vital biomarkers in multiple diseases. LncRNA HOMEOBOX A11 (HOXA11) has been found to be aberrantly expressed in some kinds of malignant tumors. In this study, we mainly discuss the oncogenic role of it in promoting malignant progression and chemoresistance in lung adenocarcinoma (LUAD) cells. The expression of HOXA11‐AS was much stronger in cisplatin‐resistant LUAD cells. Based on The Cancer Genome Atlas database, patients with high expression of HOXA11‐AS had shorter survival time. Additionally, knockdown of HOXA11‐AS caused positive changes in cell activities of LUAD. For example, cell proliferation and migration were weakened, the epithelial mesenchymal transition process was reversed, and apoptosis was induced. These changes were more obvious in cells treated with cisplatin. Next, the HOXA11‐AS/miR‐454‐3p/Stat3 (signal transducer and activator of transcription 3) pathway was found to influence the cisplatin resistance of LUAD cells. HOXA11‐AS specifically acted as a competing endogenous RNA (ceRNA) in LUAD cells. The combinations among these three genes were demonstrated. Finally, rescue assays were applied to demonstrate the ceRNA pattern consisting of HOXA11‐AS, miR‐454‐3p and Stat3. In conclusion, lncRNA HOXA11‐AS acted as a ceRNA to promote cisplatin resistance of human LUAD cells via the miR‐454‐3p/Stat3 axis.

Neat-en-ing up our understanding of p53 pathways in tumor suppression

Although the p53 transcription factor has a well-established role in tumor suppression, little is known about how the non-coding targets of p53 mediate its tumor suppression function. Analysis of ncRNAs regulated by p53 revealed Neat1 as a direct p53 target gene. Neat1 has physiological roles in the development and differentiation of the mammary gland and corpus luteum, but its roles in cancer have been conflicting. To unequivocally understand Neat1 function in cancer, we used Neat1 null mice. Interestingly, we found that Neat1 deficiency promotes transformation both in oncogene-expressing fibroblasts and in a mouse model for pancreatic cancer. Specifically, Neat1 loss in the pancreas results in the enhanced development of preneoplastic lesions associated with dampened expression of differentiation genes. While the exact mechanisms underlying tumor suppression are unknown, there are several described mechanisms that may be responsible for Neat1-mediated tumor suppression. Collectively, these findings suggest that Neat1 enforces differentiation to suppress pancreatic cancer.

Long Non-coding RNAs: Regulators of Viral Infection and the Interferon Antiviral Response

Interferons (IFNs) are a family of cytokines providing a robust first line of host innate defense against pathogenic infection, and have now been part of the standard treatment for viral infection. However, IFN based therapy can best be described as modestly effective. Long non-coding RNAs (lncRNAs) are a novel class of non-protein-coding RNAs that are capable of regulating gene expression at different levels, including chromatin, transcription, post-transcription, and translation. Recently, lncRNAs are found to be deregulated upon viral infection or IFN treatment, and some of them can modulate viral infection in an IFN-dependent or -independent manner. Due to the crucial roles of lncRNAs in viral infection and the IFN antiviral response, the modulation of specific lncRNAs may be involved to increase the IFN antiviral response and improve the clinical result of IFN-based therapy. In this review, we summarize lncRNAs that are deregulated by viral infection, with special focus on the functions and underlying mechanisms of some essential lncRNAs, and discuss their roles in viral infection and the antiviral response of IFN.

Long non-coding RNA NEAT1-modulated abnormal lipolysis via ATGL drives hepatocellular carcinoma proliferation

BACKGROUND

Abnormal metabolism, including abnormal lipid metabolism, is a hallmark of cancer cells. Some studies have demonstrated that the lipogenic pathway might promote the development of hepatocellular carcinoma (HCC). However, the role of the lipolytic pathway in HCC has not been elucidated.

METHODS

We compared levels of adipose triglyceride lipase (ATGL) in human HCC and healthy liver tissues by real time PCR, western blot and immunohistochemistry. We measured diacylglycerol(DAG) and free fatty acid (FFA) levels in HCC cells driven by the NEAT1-ATGL axis and in HCC tissues. We also assessed the effects of ATGL, DAG, FFA, and NEAT1 on HCC cells proliferation in vitro and in an orthotopic xenograft HCC mouse model. We also performed a luciferase reporter assay to investigate the interaction between NEAT1/ATGL and miR-124-3p.

RESULTS

We found that the lipolytic enzyme, ATGL is highly expressed in human HCC tissues and predicts poor prognosis. We also found that high levels of DAG and FFA are present in HCC tissues. Furthermore, the lncRNA-NEAT1 was found to modulate ATGL expression and disrupt lipolysis in HCC cells via ATGL. Notably, ATGL and its products, DAG and FFA, were shown to be responsible for NEAT1-mediated HCC cell growth. NEAT1 regulated ATGL expression by binding miR-124-3p. Additionally, NEAT1 knockdown attenuated HCC cell growth through miR-124-3p/ATGL/DAG+FFA/PPARα signaling.

CONCLUSION

Our results reveal that NEAT1-modulates abnormal lipolysis via ATGL to drive HCC proliferation.

The long non-coding RNA NEAT1 contributes to extracellular matrix degradation in degenerative human nucleus pulposus cells

Intervertebral disc degeneration is a complex disease involving genetic and environmental factors and multiple cellular processes. The role and expression of the lncRNA NEAT1 were assessed in intervertebral disc degeneration. NEAT1 expression was assessed in degenerative and control nucleus pulposus using RT-PCR. Western blotting and RT-PCR were also used to investigate p53 and p21 levels in nucleus pulposus tissues. NEAT1 function in degenerative nucleus pulposus cells was assessed with gain- and loss-of-function experiments. ERK/MAPK signaling was also examined. NEAT1, p53, and p21 were dramatically upregulated in intervertebral disc degeneration. Furthermore, catabolic MMP13 and ADAMTS5 were dysregulated and collagen II and aggrecan were downregulated after NEAT1 overexpression. This effect was reversed by transfection with si-NEAT1 in degenerative nucleus pulposus cells. In addition, NEAT1 was found to affect the activation of the ERK/MAPK pathway. The NEAT1-induced ECM degradation may involve ERK1/2/MAPK signaling. LncRNA NEAT1 may represent a novel molecular target for intervertebral disc degeneration treatment by preventing nucleus pulposus ECM degradation. Impact statement For the first time, our study demonstrates that lncRNA NEAT1 plays a role in the occurrence and development of IDD by participating in extracellular matrix remodeling. This lncRNA regulates catabolic MMP13 and ADAMTS5 and anabolic collagen II and aggrecan by affecting the ERK/MAPK signaling pathway in degenerative human nucleus pulposus (NP) cells. Our research provides a scientific basis for targeting of NEAT1 for the IDD.

Targetable long non-coding RNAs in cancer treatments

Aberrant expression of many long non-coding RNAs has been observed in various types of cancer, implicating their crucial roles in tumorigenesis and cancer progression. Emerging knowledge with regard to the critical physiological and pathological roles of long non-coding RNAs in cancers makes them potential targets in cancer treatments. In this review, we present a summary of the relatively well studied long non-coding RNAs that are involved in oncogenesis and outline their functions and functional mechanisms. Recent findings that may be utilized in therapeutic intervention are also highlighted. With the fast development in nucleic acid-based therapeutic reagents that can target disease associated RNAs, lncRNAs should be explored as potential targets in cancer treatments.

lncRNA FAM83H-AS1 is associated with the prognosis of colorectal carcinoma and promotes cell proliferation by targeting the Notch signaling pathway

The long non-coding RNA, FAM83H antisense RNA 1 (head to head) (FAM83H-AS1), has exhibited a functional role as an oncogene in a number of different types of cancer. The aim of the present study was to reveal the dysregulation of FAM83H-AS1 in colorectal carcinoma (CRC) samples and elucidate its underlying associations with the Notch signaling pathway. The expression profiles of FAM83H-AS1 and two Notch signaling-associated molecules, Notch1 and Hes family basic-helix-loop-helix transcription factor 1 (Hes1), were measured by reverse transcription-polymerase chain reaction and western blot analysis. The Pearson χ² test was employed to evaluate the associations between FAM83H-AS1 expression and clinical features. A statistically significant positive association between the expression levels of FAM83H-AS1 and those of Notch1 or Hes1 in CRC tissues was analyzed by Spearman's correlation analysis. The Kaplan-Meier method was used to compare the overall survival curves between the highly-expressed and low-expressed FAM83H-AS1 groups via a log-rank test. Specific small hairpin RNA was transfected to silence endogenous FAM83H-AS1. MTT and colony formation assays were performed to measure the growth-inhibition effect of silenced FAM83H-AS1. The levels of FAM83H-AS1, Notch1 and Hes1 were significantly increased in CRC samples and cell lines. Cell proliferation was markedly inhibited when FAM83H-AS1 was knocked down and this effect mediated by FAM83H-AS1 could be reversed by Notch1 regulators. Thus, downregulated FAM83H-AS1 exhibited an anti-proliferative role in CRC by repressing the Notch signaling pathway.

lncRNA SNHG5 is associated with poor prognosis of bladder cancer and promotes bladder cancer cell proliferation through targeting p27

Long non-coding RNAs (lncRNAs) have been identified as critical regulators in tumorigenesis. In our present study, we measured the level of small nucleolar RNA host gene 5 (SNHG5) in bladder cancer (BC) tissues and cell lines, and the correlation of the level of SNHG5 with clinicopathological features and prognosis of BC patients was analyzed. Reverse transcription-quantitative polymerase chain reaction was performed to determine the level of SNHG5 in the BC tissues and cell lines. The Kaplan-Meier method was used to analyze the long-term survival outcomes. MTT and colony formation assays were applied to assess the influence of SNHG5 on cell proliferation ability. Flow cytometry was used to measure the function of SNHG5 on cell cycle and apoptosis rate. SNGH5 was found upregulated in BC tissues and cell lines and a high level of SNGH5 was correlated with a poor prognosis. Silencing SNHG5 inhibited the proliferation ability of BC cells and such a function was attributed to its influence on cells cycle and apoptosis. Our findings imply that SNHG5 was upregulated in BC tissues and played an important role in BC progression and may be a potential therapeutic target for BC patients.

Pan-cancer analysis of long non-coding RNA NEAT1 in various cancers

Changes in the abundance and activity of long non-coding RNAs (lncRNAs) have an important impact on the development of cancer. The nuclear paraspeckle assembly transcript 1 (NEAT1) has been reported to be overexpressed in many types of cancer since its discovery. However, inconsistencies exist as NEAT1 can also function as a tumor suppressor in certain types of cancer, such as acute promyelocytic leukemia. Here we systematically describe our current understanding of NEAT1 in tumor initiation and progression. First, we analyzed the expression patterns of NEAT1 in various normal tissues and malignant cancers using data from public data portals, the Genotype-Tissue Expression Project (GTEx) and the Cancer Genome Atlas (TCGA), together with recent progress in the study of NEAT1 in various types of cancer. Second, we discussed the functions and mechanisms of NEAT1 in modulating tumor activity. Then, the upstream transcription factors and downstream microRNA targets of NEAT1 in the transcription cascade of cancers were also summarized. These data highlight the emerging role of NEAT1 in tumorigenesis, and present promising targetable pathways and clinical opportunities for tumor prevention and classifications.

The multidimensional mechanisms of long noncoding RNA function

A major shift in our understanding of genome regulation has emerged recently. It is now apparent that the majority of cellular transcripts do not code for proteins, and many of them are long noncoding RNAs (lncRNAs). Increasingly, studies suggest that lncRNAs regulate gene expression through diverse mechanisms. We review emerging mechanistic views of lncRNAs in gene regulation in the cell nucleus. We discuss the functional interactions that lncRNAs establish with other molecules as well as the relationship between lncRNA transcription and function. While some of these mechanisms are specific to lncRNAs, others might be shared with other types of genes.

Pseudogene PDIA3P1 promotes cell proliferation, migration and invasion, and suppresses apoptosis in hepatocellular carcinoma by regulating the p53 pathway

Pseudogenes are a subclass of long non-coding (lnc) RNAs that arose from protein-coding genes, but have lost the ability to produce proteins. Pseudogenes play an important role in the pathogenesis of various tumors; however, the role of pseudogenes in hepatocellular carcinoma (HCC) is poorly understood. In this study, we investigated a novel pseudogene, PDIA3P1, which was upregulated in HCC tissues compared with paired normal adjacent tissues. The expression of PDIA3P1 was significantly correlated with tumor size, metastasis, TNM stage, and overall stage. Knockdown of PDIA3P1decreased proliferation, migration, and invasion of HCC cells. PDIA3P1 knockdown also promoted cell apoptosis and inhibited tumor growth in vivo. We performed a GeneChip assay to investigate the underlying mechanism of PDIA3P1 action on biological function, and our results suggested that PDIA3P1 may promote proliferation and inhibit apoptosis of liver cancer cells by inhibiting the p53 pathway. Thus, our data suggest that PDIA3P1 acts as an oncogene in HCC and could be a potential prognostic marker and therapeutic target for HCC.

Non-coding RNAs as a new dawn in tumor diagnosis

The current knowledge about non-coding RNAs (ncRNAs) as important regulators of gene expression in both physiological and pathological conditions, has been the main engine for the design of innovative platforms to finalize the pharmacological application of ncRNAs as either therapeutic tools or as molecular biomarkers in cancer. Biochemical alterations of cancer cells are, in fact, largely supported by ncRNA disregulation in the tumor site, which, in turn, reflects the cancer-associated specific modification of circulating ncRNA expression pattern. The aim of this review is to describe the state of the art of pre-clinical and clinical studies that analyze the involvement of miRNAs and lncRNAs in cancer-related processes, such as proliferation, invasion and metastases, giving emphasis to their functional role. A central node of our work has been also the examination of advantages and criticisms correlated with the clinical use of ncRNAs, taking into account the pressing need to refine the profiling methods aimed at identify novel diagnostic and prognostic markers and the request to optimize the delivery of such nucleic acids for a therapeutic use in an imminent future.

Long Non-Coding RNA (LncRNA) HOXA11-AS Promotes Breast Cancer Invasion and Metastasis by Regulating Epithelial-Mesenchymal Transition

BACKGROUND To detect the expression of lncRNA HOXA11-AS and its biological effect in breast cancer. MATERIAL AND METHODS In this study, fluorescent quantitative real-time PCR (qRT-PCR), MTT assay and clone formation assay, flow cytometry, Transwell assay and wound healing assay, immunofluorescence, and Western blot analysis were conducted to detect the expression of lncRNA HOXA11-AS, cell proliferation activity, cell apoptosis rate and cell cycle distribution, the changes of cell invasion and metastasis capacity, and the expressions of molecular markers of epithelial-mesenchymal transition (EMT), respectively. Additionally, a nude mouse metastatic tumor model was established to study the influence of lncRNA HOXA11-AS on invasion and metastasis capacity of breast cancer cells. RESULTS The qRT-PCR experiment results showed that HOXA11-AS expression in breast cancer tissue of 50 patients was relatively higher than that in tissue adjacent to cancer. MTT assay suggested that tumor cell proliferation capacity was suppressed followed by the knockdown of lncRNA HOXA11-AS expression in MDA-MB-231 and MCF-7 cells; flow cytometry results demonstrated that interfering in lncRNA HOXA11-AS could induce tumor cell apoptosis and promote cell cycle progression to be arrested in G1/G0 stage; experiments in vivo/vitro manifested that interfering in lncRNA HOXA11-AS could inhibit tumor cell invasion and migration capacity by affecting the expressions of EMT-related molecular markers (E-cadherin, N-cadherin, Vimentin). CONCLUSIONS High expression of lncRNA HOXA11-AS promotes breast cancer invasion and metastasis by affecting EMT, and interfering in lncRAN HOXA11-AS expression provides a theoretical basis and important molecular target for inhibiting the distant metastasis of breast cancer in clinical practice.