Involvement of long non-coding RNA in colorectal cancer: From benchtop to bedside (Review)

Predicting colorectal cancer prognosis based on long noncoding RNAs of disulfidptosis genes

BACKGROUND

A recently hypothesized cause of cell death called disulfidptosis has been linked to the expansion, emigration, and vascular rebuilding of cancer cells. Cancer can be treated by targeting the pathways that trigger cell death.

AIM

To discover the long non-coding RNA of the disulfidaptosis-related lncRNAs (DRLs), prognosis clinical survival, and treat patients with colorectal cancer with medications.

METHODS

Initially, we queried the Cancer Genome Atlas database to collect transcriptome, clinical, and genetic mutation data for colorectal cancer (CRC). Training and testing sets for CRC patient transcriptome data were generated randomly. Key long non-coding RNAs (lncRNAs) related to DRLs were then identified and evaluated using a least absolute shrinkage and selection operator procedure, as well as univariate and multivariate Cox regression models. A prognostic model was then created after risk scoring. Also, Immune infiltration analysis, immune checkpoint analysis, and medication susceptibility analysis were used to investigate the causes of the different prognoses between high and low risk groups. Finally, we validated the differential expression and biomarker potential of risk-predictive lncRNAs through induction using both NCM460 and HT-29 cell lines, as well as a disulfidptosis model.

RESULTS

In this work, eight significant lncRNAs linked to disulfidptosis were found. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses of differentially expressed genes between high- and low-risk groups from the prognostic model showed a close relationship with the immune response as well as significant enrichment in neutrophil extracellular trap formation and the IL-17 signaling pathway. Furthermore, significant immune cell variations between the high-risk and low-risk groups were seen, as well as a higher incidence of immunological escape risk in the high-risk group. Finally, Epirubicin, bortezomib, teniposide, and BMS-754807 were shown to have the lowest sensitivity among the four immunotherapy drugs.

CONCLUSION

Our findings emphasizes the role of disulfidptosis in regulating tumor development, therapeutic response, and patient survival in CRC patients. For the clinical treatment of CRC, these important LncRNAs could serve as viable therapeutic targets.

Exploring the pathogenesis of colorectal carcinoma complicated with hepatocellular carcinoma via microarray data analysis

Background: Despite the increasing number of research endeavors dedicated to investigating the relationship between colorectal carcinoma (CRC) and hepatocellular carcinoma (HCC), the underlying pathogenic mechanism remains largely elusive. The aim of this study is to shed light on the molecular mechanism involved in the development of this comorbidity. Methods: The gene expression profiles of CRC (GSE90627) and HCC (GSE45267) were downloaded from the Gene Expression Omnibus (GEO) database. After identifying the common differentially expressed genes (DEGs) of psoriasis and atherosclerosis, three kinds of analyses were performed, namely, functional annotation, protein-protein interaction (PPI) network and module construction, and hub gene identification, survival analysis and co-expression analysis. Results: A total of 150 common downregulated differentially expressed genes and 148 upregulated differentially expressed genes were selected for subsequent analyses. The significance of chemokines and cytokines in the pathogenesis of these two ailments is underscored by functional analysis. Seven gene modules that were closely connected were identified. Moreover, the lipopolysaccharide-mediated signaling pathway is intricately linked to the development of both diseases. Finally, 10 important hub genes were identified using cytoHubba, including CDK1, KIF11, CDC20, CCNA2, TOP2A, CCNB1, NUSAP1, BUB1B, ASPM, and MAD2L1. Conclusion: Our study reveals the common pathogenesis of colorectal carcinoma and hepatocellular carcinoma. These common pathways and hub genes may provide new ideas for further mechanism research.

Targeting lncRNAs of colorectal cancers with natural products

Non-coding RNA (ncRNA) is one of the functional classes of RNA that has a regulatory role in various cellular processes, such as modulation of disease onset, progression, and prognosis. ncRNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), have been actively studied in recent years. The change in ncRNA levels is being actively studied in numerous human diseases, especially auto-immune disorders and cancers; however, targeting and regulating ncRNA with natural products to cure cancer has not been fully established. Recently many groups reported the relationship between ncRNA and natural products showing promising effects to serve as additional therapeutic approaches to cure cancers. This mini-review summarizes the aspects of lncRNAs related to cancer biology focusing on colorectal cancers that natural products can target.

Pyroptosis-related lncRNAs: A novel prognosis signature of colorectal cancer

Pyroptosis is a newly discovered programmed cell death mechanism involved in tumorigenesis. Long non-coding RNAs (lncRNAs) have been implicated in colorectal cancer (CRC). However, the potential role of pyroptosis-related lncRNAs (PRLs) in CRC remains unelucidated. Therefore, we retrieved transcriptomic data of CRC patients from The Cancer Genome Atlas (TCGA). With the use of univariate and multivariate Cox proportional hazards regression models and the random forest algorithm, a new risk model was constructed based on eight PRLs: Z99289.2, FENDRR, CCDC144NL-ASL, TEX41, MNX1-AS1, NKILA, LINC02798, and LINC02381. Then, according to the Kaplan-Meier plots, the relationship of PRLs with the survival of CRC patients was explored and validated with our risk model in external datasets (Gene Expression Omnibus (GEO) databases; GEO17536, n = 177, and GSE161158, n = 250). To improve its clinical utility, a nomogram combining PRLs that could predict the clinical outcome of CRC patients was established. A full-spectrum immune landscape of CRC patients mediated by PRLs could be described. The PRLs were stratified into two molecular subtypes involved in immune modulators, immune infiltration of tumor immune microenvironment, and inflammatory pathways. Afterward, Tumor Immune Dysfunction and Exclusion (TIDE) and microsatellite instability (MSI) scores were analyzed. Three independent methods were applied to predict PRL-related sensitivity to chemotherapeutic drugs. Our comprehensive analysis of PRLs in CRC patients demonstrates a potential role of PRLs in predicting response to treatment and prognosis of CRC patients, which may provide a better understanding of molecular mechanisms underlying CRC pathogenesis and facilitate the development of effective immunotherapy.

LncRNA ALMS1-IT1 is a novel prognostic biomarker and correlated with immune infiltrates in colon adenocarcinoma

Colon adenocarcinoma (COAD) is one of the most serious cancers. It is important to accurately predict prognosis and provide individualized treatment. Evidence suggests that clinicopathological features and immune status of the body are related to the occurrence and development of cancer. Expression of long non-coding RNA (LncRNA) ALMS1 intronic transcript 1 (ALMS1-IT1) is observed in some cancer types, and we believe that it may have the potential to serve as a marker of COAD. Therefore, we used the data obtained from the cancer genome atlas (TCGA) database to prove the relationship between ALMS1-IT1 and COAD. Wilcoxon rank sum test, Chi-square test, Fisher exact test and logistic regression were used to evaluate relationships between clinical-pathologic features and ALMS1-IT1 expression. Receiver operating characteristic curves were used to describe binary classifier value of ALMS1-IT1 using area under curve score. Kaplan-Meier method and Cox regression analysis were used to evaluate factors contributing to prognosis. Gene oncology (GO) and (Kyoto Encyclopedia of Genes and Genomes) KEGG enrichment analysis were used to predict the function of differentially expressed genes associated with ALMS1-IT1. Gene set enrichment analysis (GSEA) was used to predict canonical pathways associated with ALMS1-IT1.Immune infiltration analysis was performed to identify the significantly involved functions of ALMS1-IT1. Starbase database was used to predict miRNAs and RNA binding proteins (RBPs) that may interact with ALMS1-IT1. Increased ALMS1-IT1 expression in COAD was associated with N stage (P < .001), M stage (P = .003), Pathologic stage (P = .002), and Primary therapy outcome (P = .009). Receiver operating characteristic curve suggested the significant diagnostic and prognostic ability of ALMS1-IT1 (area under curve = 0.857). High ALMS1-IT1 expression predicted a poorer overall-survival (P = .005) and poorer progression-free interval (PFI) (P = .012), and ALMS1-IT1 expression was independently correlated with PFI in COAD patients (hazard ratio (HR) :1.468; 95% CI: 1.029-2.093; P =.034) (HR: 1.468; 95% CI: 1.029-2.093; P = .034). GO, KEGG, GSEA, and immune infiltration analysis showed that ALMS1-IT1 expression was correlated with regulating the function of DNA and some types of immune infiltrating cells. ALMS1-IT1 expression was significantly correlated with poor survival and immune infiltrations in COAD, and it may be a promising prognostic biomarker in COAD.

Antitumor Activity of lncRNA NBAT-1 via Inhibition of miR-4504 to Target to WWC3 in Oxaliplatin-Resistant Colorectal Carcinoma

Background

Increasing evidence shows that dysfunction of noncoding RNAs is implicated in cancer. Neuroblastoma associated transcript 1 (NBAT-1) has been identified as a tumor suppressive lncRNA that is aberrantly expressed in cancers. However, the function and the underlying mechanisms of the NBAT-1 in colorectal carcinoma (CRC) remain unknown.

Methods

Gene expression was detected by RT-qPCR. The influence of NBAT-1 on CRC was evaluated by the cell counting kit-8 (CCK-8) assay and an in vivo xenograft mouse model. The possible binding of NBAT-1 to miRNAs was predicted via the miRDB online tool and confirmed by a dual-luciferase reporter assay. Protein expression was detected by western blot.

Results

NBAT-1 expression was significantly decreased in CRC tissues, especially in patients with oxaliplatin (OXA) resistance. NBAT-1 inhibited OXA-resistant CRC cell proliferation in vitro and tumor growth in vivo. The mechanism study revealed that NBAT-1 functioned as a competing endogenous RNA (ceRNA) of miR-4504. NBAT-1 bound miR-4504 and decreased miR-4504 expression in CRC cells. Furthermore, WW-and-C2-domain-containing protein family member 3 (WWC3) was identified as a target of miR-4504. Downregulation of NBAT-1 promoted miR-4504 expression and reduced the level of WWC3. Inhibition of WWC3 by NBAT-1 depletion inactivated Hippo signalling by inhibiting the phosphorylation of large tumor suppressor kinase 1 (LATS1) and yes-associated protein (YAP). Consistently, knockdown of NBAT-1 suppressed the expression of YAP transcriptional targets.

Conclusions

These findings demonstrated that lncRNA NBAT-1 suppresses OXA-resistant CRC cell growth via inhibition of miR-4504 to regulate the WWC3/LATS1/YAP axis.

lncRNA FGD5-AS1 acts as a ceRNA to regulate lipopolysaccharide-induced injury via the miR-223-3p-3p/GAS5 axis in cardiomyocytes

Long noncoding RNAs (lncRNAs) are abnormally expressed in numerous diseases, and they are closely associated with cardiac diseases. However, the role of lncRNAs in lipopolysaccharide (LPS)-induced cardiotoxicity as well as the potential mechanism remain largely unclear. In the present study, IncRNA microarray assays were performed to analyze differential lncRNA expression in LPS-treated cardiomyocytes, and lncRNA FGD5-AS1 was one of the downregulated lncRNAs. H9C2 cells were treated with LPS, and the expression of lncRNA FGD5-AS1 was markedly downregulated. LncRNA FGD5 overexpression decreased the LPS-induced cardiomyocyte apoptosis and inflammation. Bioinformatics analysis and a luciferase reporter assay indicated that lncRNA FGD5-AS1 directly binds to miR-223-3p. A miR-222-3p mimic partially reversed the inhibitory effect of lncRNA FGD5-AS1 on the LPS-induced H9C2 cell apoptosis and inflammatory response. Moreover, miR-223-3p directly targeted growth arrest-specific transcript 5 (GAS5). LncRNA FGD5-AS1 regulated LPS-induced H9C2 cell inflammation and apoptosis via the miR-223-3p/GAS5 axis.

Autophagy and gastrointestinal cancers: the behind the scenes role of long non-coding RNAs in initiation, progression, and treatment resistance

Gastrointestinal (GI) cancers comprise a heterogeneous group of complex disorders that affect different organs, including esophagus, stomach, gallbladder, liver, biliary tract, pancreas, small intestine, colon, rectum, and anus. Recently, an explosion in nucleic acid-based technologies has led to the discovery of long non-coding RNAs (lncRNAs) that have been found to possess unique regulatory functions. This class of RNAs is >200 nucleotides in length, and is characterized by their lack of protein coding. LncRNAs exert regulatory effects in GI cancer development by affecting different functions such as the proliferation and metastasis of cancer cells, apoptosis, glycolysis and angiogenesis. Over the past few decades, considerable evidence has revealed the important role of autophagy in both GI cancer progression and suppression. In addition, recent studies have confirmed a significant correlation between lncRNAs and the regulation of autophagy. In this review, we summarize how lncRNAs play a behind the scenes role in the pathogenesis of GI cancers through regulation of autophagy.

A Novel Signature Constructed by Immune-Related LncRNA Predicts the Immune Landscape of Colorectal Cancer

Colorectal cancer (CRC) has the characteristics of high morbidity and mortality. LncRNA not only participates in the progression of CRC through genes and transcription levels, but also regulates the tumor microenvironment and leads to the malignant phenotype of tumors. Therefore, we identified immune-related LncRNAs for the construction of clinical prognostic model. We searched The Cancer Genome Atlas (TCGA) database for original data. Then we identified differentially expressed irlncRNA (DEirlncRNA), which was paired and verified subsequently. Next, univariate analysis, Lasso and Cox regression analysis were performed on the DEirlncRNA pair. The ROC curve of the signature was drawn, and the optimal cut-off value was found. Then the cohort was divided into a high-risk and a low-risk group. Finally, we re-evaluated the signature from different perspectives. A total of 16 pairs of DEirlncRNA were included in the construction of the model. After regrouping according to the cut-off value of 1.275, the high-risk group showed adverse survival outcomes, progressive clinicopathological features, specific immune cell infiltration status, and high sensitivity to some chemotherapy drugs. In conclusion, we constructed a signature composed of immune-related LncRNA pair with no requirement of the specific expression level of genes, which shows promising clinical predictive value in CRC patients.

I. A, Elbehi AM, Cash E, Adeyeye A. The Impact of Diet on the Involvement of Non-Coding RNAs, Extracellular Vesicles, and Gut Microbiome-Virome in Colorectal Cancer Initiation and Progression

Cancer is the major cause of morbidity and mortality in the world today. The third most common cancer and which is most diet related is colorectal cancer (CRC). Although there is complexity and limited understanding in the link between diet and CRC, the advancement in research methods have demonstrated the involvement of non-coding RNAs (ncRNAs) as key regulators of gene expression. MicroRNAs (miRNAs) which are a class of ncRNAs are key players in cancer related pathways in the context of dietary modulation. The involvement of ncRNA in cancer progression has recently been clarified throughout the last decade. ncRNAs are involved in biological processes relating to tumor onset and progression. The advances in research have given insights into cell to cell communication, by highlighting the pivotal involvement of extracellular vesicle (EV) associated-ncRNAs in tumorigenesis. The abundance and stability of EV associated ncRNAs act as a new diagnostic and therapeutic target for cancer. The understanding of the deranging of these molecules in cancer can give access to modulating the expression of the ncRNAs, thereby influencing the cancer phenotype. Food derived exosomes/vesicles (FDE) are gaining interest in the implication of exosomes in cell-cell communication with little or no understanding to date on the role FDE plays. There are resident microbiota in the colon; to which the imbalance in the normal intestinal occurrence leads to chronic inflammation and the production of carcinogenic metabolites that lead to neoplasm. Limited studies have shown the implication of various types of microbiome in CRC incidence, without particular emphasis on fungi and protozoa. This review discusses important dietary factors in relation to the expression of EV-associated ncRNAs in CRC, the impact of diet on the colon ecosystem with particular emphasis on molecular mechanisms of interactions in the ecosystem, the influence of homeostasis regulators such as glutathione, and its conjugating enzyme-glutathione S-transferase (GST) polymorphism on intestinal ecosystem, oxidative stress response, and its relationship to DNA adduct fighting enzyme-0-6-methylguanine-DNA methyltransferase. The understanding of the molecular mechanisms and interaction in the intestinal ecosystem will inform on the diagnostic, preventive and prognosis as well as treatment of CRC.

Identification of MFI2-AS1, a Novel Pivotal lncRNA for Prognosis of Stage III/IV Colorectal Cancer

BACKGROUND

Long noncoding RNAs (lncRNAs) have been shown to play pivotal role in pathogenesis and prognosis of cancers. Identification of novel clinical biomarkers in advanced stage colorectal cancer (CRC) is warranted.

AIMS

To identify potential lncRNAs associated with progression of stage III/IV CRC and illuminate regulatory mechanisms.

METHODS

Differentially expressed lncRNAs, mRNAs and miRNAs (DElncRNAs, DEmRNAs, and DEmiRNAs) were extracted between stage III/IV CRC and normal tissues. We used DEGs to construct a ceRNA network and analyzed correlations between key lncRNAs and overall survivals (OS) of stage III/IV CRC patients. Weighted gene co-expression network analysis (WGCNA) was applied to a pivotal lncRNA. We conducted functional enrichment analysis on target genes and constructed lncRNA-TF-mRNA network by overlapping mRNAs co-expressed with the key lncRNA and target genes of transcriptional factors (TFs).

RESULTS

A total of 26 DElncRNAs, 398 DEmiRNAs, 2155 DEmRNAs were identified. A ceRNA network was constructed with 16 lncRNAs, 20 miRNAs, and 59 mRNAs, in which MFI2-AS1 exhibited promising diagnostic efficiency. (AUC was 0.938.) MFI2-AS1 was negatively correlated to OS of stage III/IV CRC patients (P value < 0.05). KEGG analysis showed potential mRNA targets of MFI2-AS1 mainly involved in cell cycle and cytokine-cytokine receptor interaction. We identified 17 potential TFs of MFI2-AS1 and built a lncRNA-TF-mRNA network.

CONCLUSION

Our study provides novel insights into lncRNAs associated regulatory networks and reveals a promising lncRNA biomarker, MFI2-AS1, as an independent prognostic indicator and potential therapeutic target for CRC.

Silencing of lncRNA EZR-AS1 inhibits proliferation, invasion, and migration of colorectal cancer cells through blocking transforming growth factor β signaling

Long non-coding RNA (lncRNA) plays a key regulatory role in the pathogenesis of colorectal cancer (CRC). In the present study, the specific regulatory role of lncRNA ezrin antisense RNA 1 (EZR-AS1) on CRC was investigated. The expression of lncRNA EZR-AS1 was significantly up-regulated in CRC cell lines (HCT8, HCT116, HT29, and SW620 cells), which was significantly different from that of normal human fetal colonic mucosa cells (FHC cells) (P<0.01). HCT116 and HT29 cells were then transfected with EZR-AS1 shRNA (sh-EZR-AS1) to silence lncRNA EZR-AS1 (P<0.01). When compared with the Control, after transfection of SH-EZR-AS1, E-cadherin was up-regulated, Vimentin was down-regulated, the apoptosis rate was increased, the cell viability, wound healing rate, and the number of invasive cells were decreased in HCT116 and HT29 cells (P<0.05). Silencing of lncRNA EZR-AS also significantly reduced the tumor volume and weight in mice injected with sh-EZR-AS1-transfected HCT116 and HT29 cells (P<0.05). The regulatory relationship between lncRNA EZR-AS1 and transforming growth factor β (TGF-β) signaling was further identified in CRC cells. Silencing of lncRNA EZR-AS1 significantly down-regulated TGF-β, Smad2, and α-SMA expression in HCT116 and HT29 cells at the protein level (P<0.05). The intervention of SB431542 (a TGF-β receptor blocker) and silencing of Smad2 both significantly down-regulated lncRNA EZR-AS1 expression in HCT116 and HT29 cells (P<0.01). In conclusion, silencing of lncRNA EZR-AS1 inhibited the proliferation, invasion, migration, and epithelial–mesenchymal transition, and promoted the apoptosis of CRC cells through blocking TGF-β signaling.

Long noncoding RNA LINC01234 promoted cell proliferation and invasion via miR-1284/TRAF6 axis in colorectal cancer

Colorectal cancer is one of the most common and leading malignancies globally. Long noncoding RNAs (lncRNAs) function as potentially critical regulator in colorectal cancer. LINC01234, a novel lncRNA in tumor biology, regulates the progression of various tumors. However, the tumorigenic mechanism of LINC01234 in colorectal cancer is still unclear. This study was performed with the aim to prospectively investigate clinical significance, effect, and mechanism of lncRNA LINC01234 in colorectal cancer. First, we found that LINC01234, localized in the cytoplasm, was increased in both colorectal cancer cell lines and tissues. Subsequent functional assays suggested LINC01234 knockdown suppressed cell proliferation, migration, and invasion of colorectal cancer cells, while blocked cell cycle and induced cell apoptosis. Moreover, we identified that miR-1284 was target of LINC01234, we further demonstrated a negative correlation with LINC01234 in colorectal cancer tissues and cells. Furthermore, miR-1284 targeted and suppressed tumor necrosis factor receptor-associated factor 6 (TRAF6). Loss-of-function assay revealed that LINC01234 silencing suppressed colorectal cancer progression through inhibition of miR-1284. In vivo subcutaneous xenotransplanted tumor model indicated LINC01234 knockdown inhibited in vivo tumorigenic ability of colorectal cancer via downregulation of TRAF6. Collectively, this study clarified the biological significance of LINC01234/miR-1284/TRAF6 axis in colorectal cancer progression, providing insights into LINC01234 as novel potential therapeutic target for colorectal cancer therapeutic from bench to clinic.

Silence of lncRNA ANRIL represses cell growth and promotes apoptosis in retinoblastoma cells through regulating miR-99a and c-Myc

Retinoblastoma is a rare cancer of the immature retina. This study designed to see the function of the lncRNA ANRIL in retinoblastoma Y79 cells. ANRIL, miR-99a and c-Myc expression in Y79 cells was altered by transfection and then trypan blue, transwell assay and flow cytometry were carried out to evaluate the changes of cell phenotype. The connection between ANRIL, miR-99a and c-Myc was measured by luciferase reporter assay and RNA immunoprecipitation analysis. As a result, ANRIL expression was highly expressed in human retinoblastoma tissue as relative to the adjacent noncancerous tissues. ANRIL suppression inhibited Y79 cells viability, migration, invasion, while promoted apoptosis. ANRIL negatively regulated miR-99a by binding to miR-99a. Silence of miR-99a reversed the ANRIL-knockdown effects on Y79 cells. miR-99a overexpression suppressed Y79 cell viability, migration, invasion, and enhanced apoptosis through downregulating c-Myc. Meanwhile, we found that miR-99a inhibited JAK/STAT and PI3K/AKT pathways. To conclude, it seems that ANRIL suppression inhibits cell growth and metastasis in retinoblastoma Y79 cells by regulating miR-99a and c-Myc.

Long Noncoding RNA (lncRNA)-Mediated Competing Endogenous RNA Networks Provide Novel Potential Biomarkers and Therapeutic Targets for Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and has a high metastasis and reoccurrence rate. Long noncoding RNAs (lncRNAs) play an important role in CRC growth and metastasis. Recent studies revealed that lncRNAs participate in CRC progression by coordinating with microRNAs (miRNAs) and protein-coding mRNAs. LncRNAs function as competitive endogenous RNAs (ceRNAs) by competitively occupying the shared binding sequences of miRNAs, thus sequestering the miRNAs and changing the expression of their downstream target genes. Such ceRNA networks formed by lncRNA/miRNA/mRNA interactions have been found in a broad spectrum of biological processes in CRC, including liver metastasis, epithelial to mesenchymal transition (EMT), inflammation formation, and chemo-/radioresistance. In this review, we summarize typical paradigms of lncRNA-associated ceRNA networks, which are involved in the underlying molecular mechanisms of CRC initiation and progression. We comprehensively discuss the competitive crosstalk among RNA transcripts and the novel targets for CRC prognosis and therapy.

LNRRIL6, a novel long noncoding RNA, protects colorectal cancer cells by activating the IL-6-STAT3 pathway

Long noncoding RNAs (lncRNAs) are emerging as critical regulators of cancer. There is a comparable number of lncRNAs to protein‐coding genes, but the expression patterns, functions, and molecular mechanisms of most lncRNAs in colorectal cancer (CRC) remain unclear. In this study, we report the identification of a novel lncRNA, named long noncoding RNA regulating IL‐6 transcription (LNRRIL6), which is upregulated in CRC tissues and cell lines. Increased LNRRIL6 expression is associated with aggressive clinicopathological characteristics and poor prognosis of CRC patients. Functional experiments showed that enhanced expression of LNRRIL6 promotes CRC cell proliferation and survival in vitro and CRC tumor growth in vivo. Conversely, depletion of LNRRIL6 inhibits CRC cell proliferation and survival in vitro and CRC tumor growth in vivo. Mechanistically, we revealed that LNRRIL6 physically binds to the IL‐6 promoter, thereby increasing IL‐6 transcription, inducing IL‐6 autocrine signaling, and activating the IL‐6/STAT3 pathway. The expression of IL‐6 is positively associated with that of LNRRIL6 in CRC tissues. Blocking the IL‐6/STAT3 pathway using the FDA‐approved IL‐6‐receptor antagonist antibody, tocilizumab, abolished the oncogenic role of LNRRIL6 in CRC. Taken together, these findings identify a novel lncRNA, LNRRIL6, that promotes CRC cell survival through activation of the IL‐6/STAT3 pathway and suggest that LNRRIL6 may be a potential prognostic biomarker and therapeutic target for CRC.

Isosteviol Sodium Protects against Ischemic Stroke by Modulating Microglia/Macrophage Polarization via Disruption of GAS5/miR-146a-5p sponge

Recent studies have shown that transforming microglia phenotype from pro-inflammation of M1 phenotype to anti-inflammation and tissue-repairing M2 phenotype may be an effective therapeutic strategy for preventing ischemic stroke brain injury. Isosteviol Sodium (STV-Na) has shown promise as a neuroprotective agent in cerebral ischemia model, although its effect on microglial polarization and chronic recovery after stroke is not clear. Here, we demonstrated that STV-Na treatment significantly reduced cerebral ischemic damage at both acute and chronic time points. STV-Na has a profound regulatory effect on microglia response after stroke. It can promote M2 polarization and inhibit microglia-mediated inflammation (M1) response following stroke in vivo and in vitro. Furthermore, we also found that Growth Arrest-Specific 5 (GAS5) altered OGD/R-induced microglial activation by increasing Notch1 expression via miR-146a-5p, the mRNA level of GAS5 and the protein level of Notch1 in vivo and in vitro, were discovered that both downgraded with STV-Na. Taken together, the present study demonstrated that STV-Na exerted neuroprotective effects by modulating microglia/macrophage polarization in ischemic stroke via the GAS5/miR-146a-5p sponge. These findings provide new evidence that targeting STV-Na could be a treatment for the prevention of stroke-related brain damage.

Roles of long non-coding RNAs in colorectal cancer tumorigenesis: A Review

Long non-coding RNAs (lncRNAs) are newly identified potential biological and gene regulators. Similar to other cell-free circulating cancer-related nucleic acids, lncRNAs are released in the peripheral circulation of cancer patients and allow for non-invasive gene expression assessment. lncRNAs are considered to be promising biomarkers for cancer prognosis and diagnosis. Several lncRNAs have been found to regulate developmental processes in a number of biological disorders. Recent studies indicated that lncRNAs are associated with numerous diseases, most notably cancer, as they were found to be highly expressed or silenced in a number of human cancers, including colorectal cancer (CRC). Despite advances in the current detection methods, over half of cancer patients succumb to the disease, as several CRC cases are diagnosed at an advanced stage. Due to the lack of non-invasive and low-cost prognostic and diagnostic tests for CRC, the identification of novel, potentially effective biomarkers has been attracting increasing attention in recent cancer research. The present review focused on the most widely applied lncRNAs in cancer detection, including CRC, in vitro.

Long noncoding RNA NEAT1 promotes the growth of cervical cancer cells via sponging miR-9-5p

Evidence has accumulated demonstrating that long noncoding RNAs (lncRNAs) participate in the initiation and progression of cancers. In this study, we found that the lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) is significantly increased in both cervical cancer tissues and cell lines. Overexpression of NEAT1 promoted the proliferation and migration of cervical cancer cells. Molecular studies uncovered that NEAT1 functions as competitive endogenous RNA (ceRNA), binding the micro-RNA miR-9-5p and suppressing its expression. However, we consistently found that when NEAT1 was highly expressed, it attenuated the inhibitory effect of miR-9-5p on the expression of PTEN and POU2F1, which are the targets of miR-9-5p. Consistent with the negative regulation of NEAT1 on miR-9-5p, restoration of miR-9-5p inhibited the growth-promoting effects of NEAT1 on cervical cancer cells. Taken together, these results indicated that NEAT1 plays an important role in the regulation cervical cancer cell growth by targeting miR-9-5p. Our findings characterized the possible mechanism of NEAT1 in cervical cancer.

Comprehensive analysis of microarray expression profiles of circRNAs and lncRNAs with associated co-expression networks in human colorectal cancer

Increasing data demonstrate that circular RNAs (circRNAs) and long non-coding RNAs (lncRNAs) play important roles in tumorigenesis. However, the mechanisms in colorectal cancer (CRC) remain unclear. Here, hundreds of significantly expressed circRNAs, and thousands of lncRNAs as well as mRNAs were identified. By qRT-PCR, one abnormal circRNA, lncRNA, and three mRNAs were verified in 24 pairs of tissues and blood samples, respectively. Then, by GO analysis, we found that the gene expression profile of linear counterparts of upregulated circRNAs in human CRC tissues preferred positive regulation of GTPase activity, cellular protein metabolic process, and protein binding, while that of downregulated circRNAs of CRC preferred positive regulation of cellular metabolic process, acetyl-CoA metabolic process, and protein kinase C activity. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that p53 signaling pathway was an important pathway in upregulated protein-coding genes, whereas cyclic guanosine monophosphate-protein kinase G (cGMP-PKG) signaling pathway was the top enriched KEGG pathway for downregulated transcripts. Furthermore, lncRNA-mRNA co-expression analysis demonstrated that downregulated lncRNA uc001tma.3 was negatively with CDC45 and positively with ELOVL4, BVES, FLNA, and HSPB8, while upregulated lncRNA NR_110882 was positively with FZD2. In addition, lncRNA-transcription factor (TF) co-expression analysis showed that the most relevant TFs were forkhead box protein A1 (FOXA1), transcription initiation factor TFIID submint 7 (TAF7), and adenovirus early region 1A(E1A)-associated protein p300 (EP300). Our findings offer a fresh view on circRNAs and lncRNAs and provide the foundation for further study on the potential roles of circRNAs and lncRNAs in colorectal cancer.

LncRNA AB073614 induces epithelial- mesenchymal transition of colorectal cancer cells via regulating the JAK/STAT3 pathway

BACKGROUND

LncRNAs are involved in the metastasis and recurrence of human tumors, including colorectal cancer (CRC). We previously reported that lncRNA AB073614 promotes tumor proliferation and metastasis and predicted a poor clinical outcome of CRC patients. Herein, we investigated the underlying mechanism of lncRNA AB073614-related metastasis in CRC.

MATERIAL AND METHODS

The expression of lncRNA AB073614 in CRC tissues were evaluated by quantitative real-time PCR (qRT-PCR). Transwell assay was performed to detect the effects of lncRNA AB073614 on cell migration and invasion. Epithelial-mesenchymal transition (EMT) molecular markers and Janus kinase/signal transducer and activator of transcription (JAK/STAT3) pathway proteins expression levels were detected by Western blot and Immunofluorescence.

RESULTS

We confirmed that lncRNA AB073614 was highly expressed in the colorectal cancer tissues. LncRNA AB073614 knockdown in SW480 and HCT116 cells significantly promoted the protein expression levels of E-cadherin and Occludin, and decreased the expressions of N-cadherin and Vimentin, then further decreased the cell migration and invasion ability. Interestingly, the expression of phosphorylated STAT3 was also down-regulated. Furthermore, SW480 and HCT116 cells were transfected with lncRNA AB073614 vector and treated with a JAK inhibitor, AT9283. The results showed that lncRNA AB073614 regulated EMT through JAK-STAT3 signaling pathway.

CONCLUSION

All these results indicate that lncRNA AB073614 can induce the expression of EMT cell markers and regulate the process of EMT of CRC cells through regulating the JAK/STAT3 pathway activation.

Non-coding RNAs, the Trojan horse in two-way communication between tumor and stroma in colorectal and hepatocellular carcinoma

In a continuous and mutual exchange of information, cancer cells are invariably exposed to microenvironment transformation. This continuous alteration of the genetic, molecular and cellular peritumoral stroma background has become as critical as the management of primary tumor progression events in cancer cells. The communication between stroma and tumor cells within the extracellular matrix is one of the triggers in colon and liver carcinogenesis. All non- codingRNAs including long non-coding RNAs, microRNAs and ultraconserved genes play a critical role in almost all cancers and are responsible for the modulation of the tumor microenvironment in several malignant processes such as initiation, progression and dissemination. This review details the involvement of non codingRNAs in the evolution of human colorectal carcinoma and hepatocellular carcinoma in relationship with the microenvironment. Recent research has shown that a considerable number of dysregulated non- codingRNAs could be valuable diagnostic and prognostic biomarkers in cancer. Therefore, more in-depth knowledge of the role non- codingRNAs play in stroma-tumor communication and of the complex regulatory mechanisms between ultraconserved genes and microRNAs supports the validation of future effective therapeutic targets in patients suffering from hepatocellular and colorectal carcinoma, two distinctive entities which share quite a lot common non-coding RNAs.

LncRNA-LET inhibits cell viability, migration and EMT while induces apoptosis by up-regulation of TIMP2 in human granulosa-like tumor cell line KGN

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common endocrine disease characterized by hyperandrogenism, irregular menses, and polycystic ovaries. Several long non-coding RNAs (lncRNAs) are aberrantly expressed in PCOS patients; however, little is known about the effects of the lncRNA-low expression in tumor (lncRNA-LET) on PCOS. We aimed to explore the effects of lncRNA-LET on human granulosa-like tumor cell line, KGN.

METHODS

Expression of lncRNA-LET in normal IOSE80 cells and granulosa cells was determined by qRT-PCR. KGN cell viability, apoptosis and migration were measured by trypan blue exclusion method, flow cytometry assay and wound healing assay, respectively. TGF-β1 was used to induce epithelial-mesenchymal transition (EMT) process. LncRNA-LET expression and mRNA expressions of TIMP2 and EMT-related proteins were measured by qRT-PCR. Western blot analysis was used to measure the protein expression of apoptosis-related proteins, EMT-related proteins, TIMP2, and the proteins in the Wnt/β-catenin and Notch signaling pathways.

RESULTS

lncRNA-LET was down-regulated in KGN cells, and its overexpression inhibited cell viability and migration, and promoted apoptosis in KGN cells. Overexpression of lncRNA-LET increased the expression of E-cadherin and decreased the expressions of N-cadherin and vimentin in KGN cells. These effects of lncRNA-LET on KGN cells were reversed by TIMP2 suppression. Overexpression of TIMP2 inhibited cell viability, migration and EMT process, and increased apoptosis by activating the Wnt/β-catenin and Notch pathways.

CONCLUSION

Overexpression of lncRNA-LET inhibits cell viability, migration and EMT process, and increases apoptosis in KGN cells by up-regulating the expression of TIMP2 and activating the Wnt/β-catenin and notch signaling pathways.

Differential expression profiles of long noncoding RNA and mRNA in colorectal cancer tissues from patients with lung metastasis

Lungs are the most common extra-abdominal site of metastasis of colorectal cancer (CRC), in which long noncoding RNA (lncRNA) may serve a role. In the present study, a high-throughput microarray assay was performed to detect lncRNA expression and identify novel targets for further study of lung metastasis in CRC. In the CRC tissues from patients with lung metastasis, 7,632 lncRNA (3,574 upregulated and 4,058 downregulated) and 6,185 mRNA (3,394 upregulated and 2,791 downregulated) were detected to be differentially expressed with a fold change ≥2 and P<0.05 compared with the CRC tissues without metastasis. A total of six differentially regulated lncRNA were confirmed by reverse transcription-quantitative polymerase chain reaction in 20 pairs of CRC samples. Furthermore, gene ontology and pathway analysis were conducted to predict the possible roles of the identified mRNA. The upregulated mRNA were associated with cell division (biological processes), protein kinase B binding (molecular functions) and cellular components. The downregulated mRNA were associated with cell adhesion, platelet-derived growth factor binding and membrane components. Pathway analysis determined that the upregulated mRNA were associated with the Wnt signaling pathway in the CRC tissues from patients with lung metastasis, while the downregulated mRNA were associated with the phosphoinositide 3-kinase/Akt signaling pathway. The results of the present study suggested that differentially expressed lncRNA may be associated with lung metastasis and may provide insights into the biology and prevention of lung metastasis.

Downregulated long non-coding RNA CLMAT3 promotes the proliferation of colorectal cancer cells by targeting regulators of the cell cycle pathway

Over-expression of long non-coding RNA (lncRNA)-CLMAT3 is significantly associated with colorectal liver metastasis and is an independent predictor of poor survival for colorectal cancer patients. However, as little is known regarding the role of this gene in the proliferation of colorectal cancer in vitro, we investigated the involvement of lncRNA-CLMAT3 in colorectal cancer cell proliferation. In this study, we demonstrate that lncRNA-CLMAT3 expression was significantly increased in colorectal cancer cells compared with a normal intestinal mucous cell line and that inhibition of lncRNA-CLMAT3 suppressed colorectal cancer cell proliferation in vitro. We also found that this reduced colorectal cancer cell proliferation due to lncRNA-CLMAT3 knockdown is associated with G0/G1 cell-cycle arrest induction and apoptosis enhancement. Furthermore, lncRNA-CLMAT3 knockdown enhanced Cdh1 expression and resulted in p27Kip accumulation via increased Skp2 protein ubiquitination. Taken together, our findings suggest that reducing lncRNA-CLMAT3 inhibits colorectal cancer cell proliferation by affecting cell cycle components.

Long non-coding RNA RAB11B-AS1 prevents osteosarcoma development and progression via its natural antisense transcript RAB11B

Long non-coding RNAs (lncRNAs) have been shown to exert essential roles in development and progression of tumors. Here we discovered a novel lncRNA, RAB11B antisense RNA (RAB11B-AS1), which is markedly down-regulated in human osteosarcoma (OS) and associated with OS metastasis and poor prognosis. We find that reduction of RAB11B-AS1 significantly facilitates proliferation, migration and invasiveness and prevents apoptosis of OS cells and results in lower sensitivity to cisplatin in these cells. In contrast, up-regulation of RAB11B-AS1 suppresses the aggressive behaviors of OS cells. Mechanistically, down-regulation of RAB11B-AS1 elevates its sense-cognate gene RAB11B expression at both mRNA and protein levels. RAB11B-AS1 expression correlates negatively with RAB11B expression in OS tissues. Luciferase reporter assay illuminated that RAB11B-AS1 regulates RAB11B expression through antisense pairing. Most importantly, all the effects of RAB11B-AS1 were abrogated by RAB11B down-regulation. Thus our findings revealed that lnc-RAB11B-AS1 prevents osteosarcoma development and progression via inhibiting RAB11B expression, indicating lnc-RAB11B-AS1 as a potential therapeutic target for osteosarcoma.

Long non-coding RNAs: a rising biotarget in colorectal cancer

Colorectal cancer (CRC) is a common gastrointestinal cancer, with a high incidence and high mortality. Long non-coding RNAs (lncRNAs) are involved in the development, invasion and metastasis, early diagnosis, prognosis, the chemoresistance and radioresistance of CRC through interference with mRNA activity, directly combining with proteins to regulate their activity or alter their localization, influencing downstream gene expression by inhibiting RNA polymerase and regulating gene expression as competing endogenous RNAs. Recent progress in next generation sequencing and transcriptome analysis has revealed that tissue and cancer-type specific lncRNAs could be useful prognostic markers. Here, the CRC-associated lncRNAs from recent studies until October 2016 are reviewed and multiple studies that have confirmed CRC-associated lncRNAs are summarized. This review may be helpful in understanding the overall relationships between the lncRNAs involved in CRC.

Knockdown of long non-coding RNA MEG3 protects H9c2 cells from hypoxia-induced injury by targeting microRNA-183

Acute myocardial infarction (AMI) occurs when blood supply to the heart is diminished (ischemia) for long time, and ischemia is primarily caused due to hypoxia. This study evaluated the effects of long non-coding RNA maternally expressed gene 3 (MEG3) on hypoxic rat cardiomyocyte-drived H9c2 cells. Hypoxic injury was confirmed by alterations of cell viability, migration, invasion, apoptosis, and hypoxia-inducible factor 1α (HIF-1α) expression. MEG3 level in hypoxic cells and effects of its knockdown on hypoxic cells were assessed. The interactions between MEG3 and miR-183 as well as miR-183 and p27 were investigated. In addition, the effects of aberrantly expressed MEG3, miR-183, and p27 on hypoxic cells along with the activation of PI3K/AKT/FOXO3a signaling pathway were all assessed. Results showed that hypoxia induced decreases of cell viability, migration and invasion, and increases of apoptosis and expressions of HIF-1α and MEG3. Knockdown of MEG3 decreased hypoxia-induced injury in H9c2 cells. Knockdown of MEG3 also increased miR-183 expression, which was identified as a target of MEG3. The effects of MEG3 knockdown on the hypoxic cells were reversed by miR-183 silence. p27 was identified as a target gene of miR-183, and its expression negatively regulated by miR-183. The mechanistic studies revealed that knockdown of p27 decreased hypoxia-induced H9c2 cell injury by activating PI3K/AKT/FOXO3a signal pathways. These findings suggest that knockdown of MEG3 alleviates hypoxia-induced H9c2 cell injury by miR-183-mediated suppression of p27 through activation of PI3K/AKT/FOXO3a signaling pathway.

A long non-coding RNA expression signature to predict survival of patients with colon adenocarcinoma

Colon cancer is the most common type of gastrointestinal cancer and is still the leading cause of cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been proved to be superior biomarkers in cancer diagnosis and prognosis than miRNAs and protein-coding genes. In the current study, our objective was to detect novel lncRNA biomarkers by analyzing lncRNA expression profiles and clinical data in a large cohort of patients with colon patients from The Cancer Genome Atlas (TCGA). By using Cox regression analysis, we identified two lncRNAs (SNHG6 and CTD-2354A18.1) which could be independent prognostic factors for predicting clinical outcome in colon adenocarcinoma. Then a linear combination of these two lncRNA biomarkers (SNHG6 and CTD-2354A18.1), termed two-lncRNA signature, was developed in the training set as a predictor for OS in patients with colon adenocarcinoma, and validated in the testing set and the entire patient set. This two-lncRNA signature demonstrated significant prognostic performance in both the testing set and the entire patient set which classified the patients into two groups with significantly different OS. The multivariate and stratified analysis suggested that the prognostic value of the two-lncRNA signature was independent of other traditional clinical variables. Functional analysis suggested that these two lncRNA biomarkers might be mainly involved in transcription/translation-related or DNA repair-related biological processes. In summary, our results warrant further studies on these lncRNAs that will improve our understanding of the mechanisms associated with pathogenesis and progression of colon adenocarcinoma.

Association of a novel genetic variant in RP11-650L12.2 with risk of colorectal cancer in Han Chinese population

BACKGROUND

This study aimed to investigate the associations of selected polymorphisms in RP11-650L12.2 with the risk of colorectal cancer (CRC) in a Chinese population.

METHODS

A total of 821 CRC cases (test set: 320, validation set: 501) and 857 healthy controls (test set: 319, validation set: 538) were enrolled in this study. Demographic characteristics and lifestyle information were collected by a validated questionnaire. A sample of 5ml venous blood was collected from each subject for DNA isolation, and the selected polymorphisms (rs144182521, rs514743, rs76071148, rs149941240) were genotyped by MassArray technique.

RESULTS

The rs149941240 polymorphism was significantly associated with the risk of CRC, with ORs of 1.50 (95% CI: 1.15-1.96) by co-dominant model and 1.45 (95% CI: 1.21-1.87) by dominant model in the test set, respectively. Correspondingly, the ORs were 1.48 (95% CI: 1.19-1.82) and 1.41 (95% CI: 1.15-1.73) in the validation set, respectively. The crossover analysis showed that non-smokers with the variant genotypes in rs149941240 had a significantly increased risk of CRC than those with wild genotype by dominant model in the validation set (OR 1.42, 95% CI 1.04-1.96). However, no gene-environment multiplicative interactions of rs149941240 with tobacco smoking were found on risk of CRC.

CONCLUSIONS

Our findings suggest that rs149941240 polymorphism was associated with the risk of CRC, and might contribute to the susceptibility to CRC. The effects of this polymorphism should be validated in a larger sample and require further mechanistic investigations to determine the nature of its influence on CRC.

Long non-coding RNA AK093407 promotes proliferation and inhibits apoptosis of human osteosarcoma cells via STAT3 activation

Osteosarcoma is a malignant tumor of the skeletal system. Long non-coding RNAs (lncRNAs) have been shown to play significant role in osteosarcoma. The present study evaluated the effects and mechanism of lncRNA AK093407 in osteosarcoma. The study included human osteosarcoma cell line, U-2OS. Cell proliferation, viability, and apoptosis were measured using Ki-67 proliferation assay, MTT assay, and Annexin V/PI staining assay, respectively. Relative mRNA and protein expressions were measured using qRT-PCR and western blot, respectively. Interaction between AK093407 and STAT3 was identified using mass spectrometry and RNA pull-down assay. Results revealed that AK093407 was highly expressed in osteosarcoma cells and tissues. Then we demonstrated that overexpression of AK093407 promoted cell proliferation and viability and inhibited apoptosis, whereas suppression of AK093407 showed opposite effects. In addition, AK093407 regulated the expression of genes and proteins (Bcl-2, TGF-β, NF-κB, and PCNA) involved in the cell proliferation, viability, and apoptosis. Furthermore, we showed that AK093407 interacted with STAT3, and promoted its phosphorylation. Lastly, we showed that STAT3 activation was essential for the effects of AK093407 on cell proliferation and apoptosis as the overexpression of AK093407 in the presence of STAT3 inhibitor did not promote cell proliferation and inhibit cell apoptosis. AK093407 is highly expressed in osteosarcoma cells and tissues, and promotes cell proliferation and viability and inhibits apoptosis of osteosarcoma cell line U-2OS via STAT3 activation.

Assessment of histone tail modifications and transcriptional profiling during colon cancer progression reveals a global decrease in H3K4me3 activity

During colon cancer, epigenetic alterations contribute to the dysregulation of major cellular functions and signaling pathways. Modifications in chromatin signatures such as H3K4me3 and H3K9ac, which are associated with transcriptionally active genes, can lead to genomic instability and perturb the expression of gene sets associated with oncogenic processes. In order to further elucidate early pre-tumorigenic epigenetic molecular events driving CRC, we integrated diverse, genome-wide, epigenetic inputs (by high throughput sequencing of RNA, H3K4me3, and H3K9ac) and compared differentially expressed transcripts (DE) and enriched regions (DER) in an in-vivo rat colon cancer progression model. Carcinogen (AOM) effects were detected genome-wide at the RNA (116 DE genes), K9ac (49 DERs including 24 genes) and K4me3 (7678 DERs including 3792 genes) level. RNA-seq differential expression and pathway analysis indicated that interferon-associated innate immune responses were impacted by AOM exposure. Despite extensive associations between K4me3 DERs and colon tumorigenesis (1210 genes were linked to colorectal carcinoma) including FOXO3, GNAI2, H2AFX, MSH2, NR3C1, PDCD4 and VEGFA, these changes were not reflected at the RNA gene expression level during early cancer progression. Collectively, our results indicate that carcinogen-induced changes in gene K4me3 DERs are harbingers of future transcriptional events, which drive malignant transformation of the colon.

Long noncoding RNAs in the progression, metastasis, and prognosis of osteosarcoma

Long noncoding RNAs (lncRNAs) are a class of non-protein-coding molecules longer than 200 nucleotides that are involved in the development and progression of many types of tumors. Numerous lncRNAs regulate cell proliferation, metastasis, and chemotherapeutic drug resistance. Osteosarcoma is one of the main bone tumor subtypes that poses a serious threat to adolescent health. We summarized how lncRNAs regulate osteosarcoma progression, invasion, and drug resistance, as well as how lncRNAs can function as biomarkers or independent prognostic indicators with respect to osteosarcoma therapy.

ANRIL is associated with the survival rate of patients with colorectal cancer, and affects cell migration and invasion in vitro

Antisense noncoding RNA in the INK4 locus (ANRIL) has been reported to be upregulated in various types of human cancer, and is also highly expressed in normal human tissue. The aim of the present study was to identify whether ANRIL may be a possible target for colorectal cancer (CRC) therapy. Reverse transcription‑quantitative polymerase chain reaction was used to quantify the expression levels of the long noncoding RNA (lncRNA) ANRIL in 97 paired CRC and adjacent non‑neoplastic tissue samples. In addition, the HT29 and RKO human CRC cell lines underwent ANRIL RNA interference, and knockdown efficiency was evaluated by western blotting. Cell viability, and migratory and invasive ability were subsequently assessed. The CRC tissues were revealed to express higher levels of ANRIL lncRNA compared with the adjacent non‑neoplastic tissues (P<0.05). Furthermore, high ANRIL expression was significantly associated with reduced survival rate (P<0.05). ANRIL gene expression was successfully silenced in human CRC cells. ANRIL knockdown decreased proliferation, inhibited migration and invasion, and reduced the colony‑forming ability of the cells. These data indicated that the lncRNA ANRIL is upregulated in CRC tissues, and is associated with CRC cell pathogenesis. Furthermore, the underlying mechanisms of these effects may be exploited for therapeutic benefit.

LncRNA TUG1 is upregulated and promotes cell proliferation in osteosarcoma

OBJECTIVE

To examine the expression and function of long non-coding RNA taurine up-regulated 1 (TUG1) in human osteosarcoma cells.

METHODS

Real-time quantitive PCR was used to detect the transcription level of TUG1 in a series of osteosarcoma cell lines. Knockdown of TUG1 in U2OS cells was carried out by transient transfection of siRNAs. MTT assay was performed to access the cell growth rates. Afterwards, RNA and protein of these cells were extracted to analyze the transfection efficient as well as the expression of other molecules.

RESULTS

Compared to the normal cell line, TUG1 exhibited a significant upregulation in osteosarcoma cells. Phenotyping analysis showed the growth-promotion activity of TUG1, since knockdown of TUG1 resulted in declined proliferation. We also found that AKT phosphorylation was impaired after TUG1 was inhibited, suggesting that the AKT pathway was involved in the regulation of TUG1 in U2OS cells.

CONCLUSION

Our data provided evidence that TUG1 was upregulated and acted as a possible oncogene via positively regulating cell proliferation in osteosarcoma cells.

Genome-wide analysis of long noncoding RNA (lncRNA) expression in colorectal cancer tissues from patients with liver metastasis

The liver is the most frequent site of metastasis in colorectal cancer (CRC), in which long noncoding RNAs (lncRNAs) may play a crucial role. In this study, we performed a genome‐wide analysis of lncRNA expression to identify novel targets for the further study of liver metastasis in CRC. Samples obtained from CRC patients were analyzed using Arraystar human 8 × 60K lncRNA/mRNA v3.0 microarrays chips to find differentially expressed lncRNAs and mRNAs. The results were confirmed by quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR). The differentially expressed lncRNAs and mRNAs were identified through fold change filtering. Gene ontology (GO) and pathway analyses were performed using standard enrichment computational methods. In the CRC tissues from patients with liver metastasis, 2636 lncRNAs were differentially expressed, including 1600 up‐regulated and 1036 down‐regulated over two‐fold compared with the CRC tissues without metastasis. Among the 1584 differentially expressed mRNAs, 548 were up‐regulated and 1036 down‐regulated. GO and pathway analysis of the up‐regulated and down‐regulated mRNAs yielded different results. The up‐regulated mRNAs were associated with single‐organism process (biological process), membrane part (cellular component), and transporter activity (molecular function), whereas the down‐regulated mRNAs were associated with cellular process, membrane, and binding, respectively. In the pathway analysis, 27 gene pathways associated with the up‐regulated mRNAs and 51 gene pathways associated with the down‐regulated mRNAs were targeted. The significant changes in NQO2 (NM_000904) mRNA and six associated lncRNAs were selected for validation by qRT‐PCR. Aberrantly expressed lncRNAs may play an important role in the liver metastasis of CRC. The further study can provide useful insights into the biology and, ultimately, the prevention of liver metastasis.

Overexpression of lncRNA AFAP1-AS1 correlates with poor prognosis and promotes tumorigenesis in colorectal cancer

Accumulating evidence has shown that long non-coding RNAs (lncRNAs) are emerging as key molecules in human malignancies. The lncRNA actin filament associated protein 1 antisense RNA1 (AFAP1-AS1) was recently found deregulated in several cancers. However, its expression pattern, clinical performance and functional roles in colorectal cancer (CRC) had not been addressed. In this study, we found that AFAP1-AS1 was aberrantly over-expressed in CRC tissues and closely correlated with tumor size, TNM stage and distant metastasis. Kaplan-Meier analysis indicated that patients with high level of AFAP1-AS1 expression had poorer overall survival (OS) and disease-free survival (DFS). Univariate and multivariable Cox regression analyses further identified that up-regulated AFAP1-AS1 might act as an independent prognostic factor for CRC patients. Moreover, AFAP1-AS1 depletion resulted in the inhibition of CRC cell proliferation and colony formation. In addition, AFAP1-AS1 knockdown induced G0/G1 cell cycle arrest in CRC cells. Taken together, our findings indicate that AFAP1-AS1 is significantly up-regulated in CRC, which may act as an oncogene and correlate with tumor malignant progression and poor prognosis of CRC. This study may shed a new light on better understanding the pathogenesis of CRC. Moreover, AFAP1-AS1 also may be a promising diagnostic and therapeutic target for this deadly disease.

Regulatory Roles of Non-Coding RNAs in Colorectal Cancer

Non-coding RNAs (ncRNAs) have recently gained attention because of their involvement in different biological processes. An increasing number of studies have demonstrated that mutations or abnormal expression of ncRNAs are closely associated with various diseases including cancer. The present review is a comprehensive examination of the aberrant regulation of ncRNAs in colorectal cancer (CRC) and a summary of the current findings on ncRNAs, including long ncRNAs, microRNAs, small interfering RNAs, small nucleolar RNAs, small nuclear RNAs, Piwi-interacting RNAs, and circular RNAs. These ncRNAs might become novel biomarkers and targets as well as potential therapeutic tools for the treatment of CRC in the near future and this review may provide important clues for further research on CRC and for the selection of effective therapeutic targets.