Transcriptional profiling analysis and functional prediction of long noncoding RNAs in cancer

Targeting lncRNA16 by GalNAc-siRNA conjugates facilitates chemotherapeutic sensibilization via the HBB/NDUFAF5/ROS pathway

Chemoresistance is a significant barrier to effective cancer treatment. Potential mechanisms for chemoresistance include reactive oxygen species (ROS) accumulation and expression of chemoresistance-promoting genes. Here, we report a novel function of lncRNA16 in the inhibition of ROS generation and the progression of chemoresistance. By analyzing the serum levels of lncRNA16 in a cohort of 35 patients with non-small cell lung cancer (NSCLC) and paired serum samples pre- and post-treatment from 10 NSCLC patients receiving neoadjuvant platinum-based chemotherapy, performing immunohistochemistry (IHC) assays on 188 NSCLC tumor samples, using comprehensive identification of RNA-binding proteins by mass spectrometry (ChIRP-MS) assays, as well as RNA immunoprecipitation (RIP) and RNA pull-down analyses, we discovered that patients with increased serum levels of lncRNA16 exhibited a poor response to platinum-based chemotherapy. The expression of hemoglobin subunit beta (HBB) and NDUFAF5 significantly increases with the development of chemoresistance. LncRNA16 binds to HBB and promotes HBB accumulation by inhibiting autophagy. LncRNA16 can also inhibit ROS generation via the HBB/NDUFAF5 axis and function as a scaffold to facilitate the colocalization of HBB and NDUFAF5 in the mitochondria. Importantly, preclinical studies in mouse models of chemo-resistant NSCLC have suggested that lncRNA16 targeting by trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNA restores chemosensitivity and results in tumor growth inhibition with no detectable toxicity in vivo. Overall, lncRNA16 is a promising therapeutic target for overcoming chemoresistance, and the combination of first-line platinum-based chemotherapy with lncRNA16 intervention can substantially enhance anti-tumor efficacy.

Knockdown of Long Noncoding RNA 01124 Inhibits the Malignant Behaviors of Colon Cancer Cells via miR-654-5p/HAX-1

Background

Previous studies have shown that long noncoding RNAs (lncRNAs) play a key role in cancer, including colon cancer (CC). However, the exact role of long noncoding RNA 01124 (LINC01124) in CC and its mechanisms of action remain unknown. In this study, we investigated the functional effects and the possible mechanism of LINC01124 in CC.

Methods

We first determined the expression of LINC01124 in CC tissues (The Cancer Genome Atlas (TCGA) database) and cell lines (quantitative real-time polymerase chain reaction (qRT-PCR)). Functional analysis via Cell Counting Kit-8 (CCK-8), colony formation, cell cycle, wound healing and Transwell assays were performed, and a mechanistic experiment was performed with the western blotting. The function of LINC01124 was also determined in vivo using nude BALB/c mice.

Results

The results showed that LINC01124 was upregulated in CC tissues and cell lines. Functional studies showed that knockdown of LINC01124 significantly suppressed the proliferation, migration, and invasion of colon cancer cells in vitro and in vivo. Subsequent mechanistic experiments indicated that LINC01124 acted as a sponge to suppress microRNA 654-5p, which targeted HAX-1. Downregulation of LINC01124 decreased the expression of HAX-1, and overexpression of the miR-654-5p inhibitor attenuated the sh-LINC01124-induced inhibition of CC cell proliferation, migration, and invasion.

Conclusion

Collectively, this study revealed that the knockdown of LINC01124 inhibited the malignant behaviors of CC via the miR-654-5p/HAX-1 axis, suggesting that LINC01124 might be a therapeutic target for CC treatment.

Cuproptosis-related lncRNA predict prognosis and immune response of lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) accounts for 50% of lung cancers, with high mortality and poor prognosis. Long non-coding RNA (lncRNA) plays a vital role in the progression of tumors. Cuproptosis is a newly discovered form of cell death that is highly investigated. Therefore, in the present study, we aimed to investigate the role of cuproptosis-related lncRNA signature in clinical prognosis prediction and immunotherapy and the relationship with drug sensitivity.

MATERIAL AND METHODS

Genomic and clinical data were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, and cuproptosis-related genes were obtained from cuproptosis-related studies. The prognostic signature was constructed by co-expression analysis and Cox regression analysis. Patients were divided into high and low risk groups, and then, a further series of model validations were carried out to assess the prognostic value of the signature. Subsequently, lncRNAs were analyzed for gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes Enrichment (KEGG), immune-related functions, and tumor mutation burden (TMB). Finally, we used tumor immune dysfunction and exclusion (TIDE) algorithms on immune escape and immunotherapy of cuproptosis-related lncRNAs, thereby identifying its sensitivity toward potential drugs for LUAD.

RESULTS

A total of 16 cuproptosis-related lncRNAs were obtained, and a prognostic signature was developed. We found that high-risk patients had worse overall survival (OS) and progression-free survival (PFS) and higher mortality. Independent prognostic analyses, ROC, C-index, and nomogram showed that the cuproptosis-related lncRNAs can accurately predict the prognosis of patients. The nomogram and heatmap showed a distinct distribution of the high- and low-risk cuproptosis-related lncRNAs. Enrichment analysis showed that the biological functions of lncRNAs are associated with tumor development. We also found that immune-related functions, such as antiviral activity, were suppressed in high-risk patients who had mutations in oncogenes. OS was poorer in patients with high TMB. TIDE algorithms showed that high-risk patients have a greater potential for immune escape and less effective immunotherapy.

CONCLUSION

To conclude, the 16 cuproptosis-related lncRNAs can accurately predict the prognosis of patients with LUAD and may provide new insights into clinical applications and immunotherapy.

Identification of a Two-lncRNA Signature with Prognostic and Diagnostic Value for Hepatocellular Carcinoma

Background

Accumulating evidence has revealed the important role of long noncoding RNAs (lncRNA) in tumorigenesis and progression of hepatocellular carcinoma (HCC). This study aimed to identify potential lncRNAs that can serve as diagnostic and prognostic signatures for HCC.

Methods

Expression profiling analysis was performed to identify differentially expressed lncRNAs (DElncRNA) between HCC and matched normal samples by integrating two independent microarray datasets. Functional Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were explored by Gene Set Variation Analysis. The prognostic and diagnostic models were developed based on two DElncRNAs. Real-time PCR was used to quantify the relative expressions of candidate lncRNAs.

Results

Two robust DElncRNAs were identified and verified by quantitative PCR between HCC and matched normal samples. Function enrichment analysis revealed that they were associated with the wound healing process. The two lncRNAs were subsequently used to construct a prognostic risk model for HCC. Patients with high-risk scores estimated by the model showed a shorter survival time than low-risk patients (P < 0.001). Besides, the two lncRNA-based HCC diagnostic models exhibited good performance in discriminating HCC from normal samples on both training and test sets. The values of area under the curve (AUC) for early (I–II) and late (III–IV) HCC detection were 0.88 and 0.93, respectively.

Conclusions

The two wound healing-related DElncRNAs showed robust performance for HCC prognostic prediction and detection, implying their potential role as diagnostic and prognostic markers for HCC.

miR-556-3p/Disabled Homolog 2-Interacting Protein (dab2ip) Promotes Cancer Progression by Down-Regulating Bcl-2-Like Protein 11 (BIM) Expression in Colorectal Cancer

Colorectal cancer (CRC) is a major threat affecting human health. Studies have shown that miR-556-3p can regulate dab2ip and promote tumor deterioration, and up-regulation of BIM inhibits CRC cell progression. However, the interaction between miR-556-3p/dab2ip and BIM in CRC is unknown. We examined miR-556-3p expression in CRC tissues and cells by RT-qPCR. The impact of miR-556-3p/dab2ip and BIM on CRC cell behaviors were assessed by western blot, transwell and MTT assay. miR-556-3p was highly expressed in CRC and its overexpression increased CRC cell proliferation and migration as well as up-regulated dab2ip and Ki-67 expression. Besides, miR-556-3p could target the BIM and overexpressed miR-556-3p decreased BIM expression. However, silencing of BIM abrogated the impact of overexpressed miR-556-3p on CRC cell proliferation and migration. In conclusion, miR-556-3p/dab2ip promotes cell growth by down-regulating the expression of BIM, thereby promoting the progression of CRC.

Differential expression of long non-coding RNAs in the hippocampus of mice exposed to PM2.5 in Dalian, China

Evidence is mounting that PM_2.5 exposure could lead to learning disability, memory deficits, and cognitive impairment; however, the underlying mechanisms are still not well demonstrated yet. Long non-coding RNAs (LncRNAs) play a crucial role in many human diseases. Although the relationship of Alzheimer's disease (AD) and lncRNAs have been discovered, the role of lncRNA in AD-like phenotype induced by PM_2.5 needs further exploration. In this study, we profiled the expression of messenger RNAs (mRNAs) and lncRNAs in hippocampus after confirming the AD-like changes in mice. Compared with the control group, a total of 478 mRNAs and 151 lncRNAs were dysregulated after PM_2.5 exposure. ECM-receptor interaction, focal adhesion, complement and coagulation cascades, and AGE-RAGE signaling pathway were found dysregulated through lncRNA-co-expressed genes analysis based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Meanwhile, the genes related to microglia were significantly altered, such as CX3CR1, CD163, lncRNA Gm44750, and lncRNA Gm43509. Above evidences suggested that microglia-related lncRNAs dysregulation probably plays a crucial role in PM_2.5exposure-associated learning and memory deficits.

Revealing the Role of lncRNA CCDC144NL-AS1 and LINC01614 in Gastric Cancer via Integrative Bioinformatics Analysis and Experimental Validation

Long non-coding RNAs (lncRNAs) are key regulators in the pathophysiology of gastric cancer, and lncRNAs have been regarded as potential biomarkers and therapeutic targets for gastric cancer. The present study performed the WGCNA analysis of the GSE70880 dataset and aimed to identify novel lncRNAs associated with gastric cancer progression. Based on the WGCNA, the lncRNAs and mRNA co-expression network were constructed. A total of four modules were identified and the eigengenes in different modules were involved in various key signaling pathways. Furthermore, the co-expression networks were constructed between the lncRNAs and mRNA; this leads to the identification of 6 modules, which participated in various cellular pathways. The survival analysis showed that high expression of CCDC144NL antisense RNA 1 (CCDC144NL-AS1) and LINC01614 was positively correlated with the poor prognosis of patients with gastric cancer. The in vitro validation results showed that CCDC144NL-AS1 and LINC01614 were both up-regulated in the gastric cancer cells. Silence of CCDC144NL-AS1 and LINC01614 both significantly suppressed the cell proliferation and migration of gastric cancer cells, and also promoted the chemosensitivity of gastric cancer cells to 5-fluorouracil. Collectively, our results suggested that the newly identified two lncRNAs (CCDC144NL-AS1 and LINC01614) may act as oncogenes in gastric cancer.

SCARA5 inhibits gastric cancer progression via epithelial-mesenchymal transition suppression

Scavenger receptor class A member 5 (SCARA5) has been reported to be implicated in several types of cancer. However, its biological roles and mechanism of SCARA5 in gastric cancer (GC) have not been elucidated. In the present study, SCARA5 expression was found to be downregulated in GC which was associated with promoter methylation. The protein level of SCARA5 was negatively associated with aggressive clinicopathological characteristics, as well as poor prognosis. Moreover, SCARA5 overexpression markedly suppressed the growth, migration and invasion of GC cell lines in vitro. Furthermore, upregulation of SCARA5 inhibited gastric tumor growth and metastasis in a xenograft model. Mechanistic analysis revealed that SCARA5 suppressed the migration and invasion of GC cells via inhibiting epithelial-mesenchymal transition (EMT) and inactivating MMP-2 and MMP-9. Taken together, these results demonstrated that SCARA5 might play vital roles in the GC genesis and progression and could serve as a potential biomarker for diagnosis and therapeutic target of GC.

Expression profiles of long non-coding RNAs in the cartilage of patients with knee osteoarthritis and normal individuals

Knee osteoarthritis is caused by a multifactorial imbalance in the synthesis and degradation of knee chondrocytes, subchondral bone and extracellular matrix. Abnormal expression of long non-coding RNAs (lncRNAs) affects the metabolism, synovitis, autophagy and apoptosis of chondrocytes, as well as the production of cartilage matrix. The aim of the present study was to identify novel targets for the treatment of osteoarthritis and to examine the pathogenesis of the disease. The lncRNA expression profiles of seven patients with knee osteoarthritis and six healthy controls were examined by RNA-sequencing. Differentially expressed lncRNAs were selected for bioinformatics analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Reverse transcription-quantitative PCR (RT-qPCR) was used to further investigate the differential expression of the lncRNAs. A total of 23,583 lncRNAs were identified in osteoarthritis cartilage, including 5,255 upregulated and 5,690 downregulated lncRNAs, compared with normal cartilage. Although there were more downregulated lncRNAs compared with upregulated lncRNAs, among the changed lncRNAs (fold-change >6), there were more upregulated lncRNAs compared with downregulated lncRNAs. Several lncRNAs exhibiting differences were identified as potential therapeutic targets in knee osteoarthritis. GO and KEGG pathway analyses were performed for the target genes of the differentially expressed lncRNAs. RT-qPCR validation was performed on three randomly selected upregulated and downregulated lncRNAs. The results of RT-qPCR were consistent with the findings obtained by RNA-sequencing analysis. The findings from the present study may contribute to the diagnosis of osteoarthritis and may predict the development of osteoarthritis. Furthermore, the differentially expressed lncRNAs may aid in the identification of novel candidate targets for the treatment of knee osteoarthritis.

MetaDE-Based Analysis of circRNA Expression Profiles Involved in Gastric Cancer

BACKGROUND

Circular RNAs (circRNAs) could play carcinogenic roles in gastric cancer (GC) and have potential to be biomarkers for GC early diagnosis, which needs to be further excavated and supported by more evidence.

AIMS

The study aims to identify more authentic circRNA expression profiles that could function as potential biomarkers in GC.

METHODS

circRNA expression data in three microarrays were downloaded from Gene Expression Omnibus datasets. A systematic meta-analysis based on an integrated dataset pre-processed from the three microarrays was conducted to identify a panel of differentially expressed circRNAs (DEcircs) by using the metaDE package. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes term enrichment were used to note the corresponding functions of DEcircs. Quantitative real-time polymerase chain reaction was applied to verify the DEcircs expression in cancer tissues and adjacent paracancerous tissues. A GC risk-related circRNAs-miRNAs-mRNAs network was further constructed and analyzed.

RESULTS

MetaDE analysis suggested 64 DEcircs between cancer tissues and adjacent normal tissues. GO and KEGG analysis showed that the parental genes of these DEcircs were mainly associated with histone methylation, Wnt signalosome and histone methylation activity. Hsa_circ_0005927 and hsa_circ_0067934 were verified in GC tissues, and a GC risk-related network was constructed.

CONCLUSION

MetaDE-based circRNA expression profiles revealed a series of potential biomarkers involved in GC. Two circRNAs, hsa_circ_0005927 and hsa_circ_0067934, could be more authentic biomarkers for GC screening. The GC risk-related network of hsa_circ_0005927/hsa_circ_0067934 and their downstream targets will provide new genetic insights for GC research.

Roles of long non-coding RNAs in the hallmarks of glioma

Glioma is one of the most common types of tumor of the central nervous system. Due to the aggressiveness and invasiveness of high-level gliomas, the survival time of patients with these tumors is short, at ~15 months, even after combined treatment with surgery, radiotherapy and/or chemotherapy. Recently, a number of studies have demonstrated that long non-coding RNA (lncRNAs) serve crucial roles in the multistep development of human gliomas. Gliomas acquire numerous biological abilities during multistep development that collectively constitute the hallmarks of glioma. Thus, in this review, the roles of lncRNAs associated with glioma hallmarks and the current and future prospects for their development are summarized.

Identification of lncRNA biomarkers for lung cancer through integrative cross-platform data analyses

This study was designed to identify lncRNA biomarker candidates using lung cancer data from RNA-Seq and microarray platforms separately.

Lung cancer datasets were obtained from the Gene Expression Omnibus (GEO, n = 287) and The Cancer Genome Atlas (TCGA, n = 216) repositories, only common lncRNAs were used. Differentially expressed (DE) lncRNAs in tumors with respect to normal were selected from the Affymetrix and TCGA datasets. A training model consisting of the top 20 DE Affymetrix lncRNAs was used for validation in the TCGA and Agilent datasets. A second similar training model was generated using the TCGA dataset.

First, a model using the top 20 DE lncRNAs from Affymetrix for training and validated using TCGA and Agilent, achieved high prediction accuracy for both training (98.5% AUC for Affymetrix) and validation (99.2% AUC for TCGA and 92.8% AUC for Agilent). A similar model using the top 20 DE lncRNAs from TCGA for training and validated using Affymetrix and Agilent, also achieved high prediction accuracy for both training (97.7% AUC for TCGA) and validation (96.5% AUC for Affymetrix and 80.9% AUC for Agilent). Eight lncRNAs were found to be overlapped from these two lists.

Integrative Analysis for the Roles of lncRNAs in the Immune Responses of Mouse PBMC Exposed to Low-Dose Ionizing Radiation

It is well accepted that low-dose ionizing radiation (LDIR) modulates a variety of immune responses that have exhibited the properties of immune hormesis. Alterations in messenger RNA (mRNA) and long noncoding RNA (lncRNA) expression were to crucially underlie these LDIR responses. However, lncRNAs in LDIR-induced immune responses have been rarely reported, and its functions and molecular mechanisms have not yet been characterized. Here, we used microarray profiling to determine lncRNA in BALB/c mice exposed to single (0.5 Gy×1) and chronic (0.05 Gy×10) low-dose γ-rays radiation (Co⁶⁰). We observed that a total of 8274 lncRNAs and 7240 mRNAs were altered in single LDIR, while 2077 lncRNAs and 796 mRNAs in chronic LDIR. The biological functions of these upregulated mRNAs in both 2 groups using Gene Ontology functional and pathway enrichment analysis were significantly enriched in immune processes and immune signaling pathways. Subsequently, we screened out the lncRNAs involved in regulating these immune signaling pathways and examined their potential functions by lncRNAs-mRNAs coexpression networks. This is the first study to comprehensively identify lncRNAs in single and chronic LDIR responses and to demonstrate the involvement of different lncRNA expression patterns in LDIR-induced immune signaling pathways. Further systematic research on these lncRNAs will provide new insights into our understanding of LDIR-modulated immune hormesis responses.

LncRNA HRCEG, regulated by HDAC1, inhibits cells proliferation and epithelial-mesenchymal-transition in gastric cancer

Recently, a number of long noncoding RNAs (lncRNAs) have been reported to play significant roles in human tumorigenesis. However, only few gastric cancer related lncRNAs have been well characterized. Here, we identified one lncRNA HRCEG, whose expression was decreased in the gastric cancer tissues compared with adjacent normal tissues. Overexpression of HRCEG significantly promoted cell apoptosis and inhibited cell proliferation. Importantly, we demonstrated that HRCEG levels inversely correlated with EMT process and HRCEG was regulated by the histone deacetylase 1 (HDAC1) in gastric cancer. These findings suggest that HRCEG might be regulated by HDAC1 to inhibit gastric cancer progress and metastatic capability via EMT pathway.

Computational models for lncRNA function prediction and functional similarity calculation

From transcriptional noise to dark matter of biology, the rapidly changing view of long non-coding RNA (lncRNA) leads to deep understanding of human complex diseases induced by abnormal expression of lncRNAs. There is urgent need to discern potential functional roles of lncRNAs for further study of pathology, diagnosis, therapy, prognosis, prevention of human complex disease and disease biomarker detection at lncRNA level. Computational models are anticipated to be an effective way to combine current related databases for predicting most potential lncRNA functions and calculating lncRNA functional similarity on the large scale. In this review, we firstly illustrated the biological function of lncRNAs from five biological processes and briefly depicted the relationship between mutations or dysfunctions of lncRNAs and human complex diseases involving cancers, nervous system disorders and others. Then, 17 publicly available lncRNA function-related databases containing four types of functional information content were introduced. Based on these databases, dozens of developed computational models are emerging to help characterize the functional roles of lncRNAs. We therefore systematically described and classified both 16 lncRNA function prediction models and 9 lncRNA functional similarity calculation models into 8 types for highlighting their core algorithm and process. Finally, we concluded with discussions about the advantages and limitations of these computational models and future directions of lncRNA function prediction and functional similarity calculation. We believe that constructing systematic functional annotation systems is essential to strengthen the prediction accuracy of computational models, which will accelerate the identification process of novel lncRNA functions in the future.

SP1-DLEU1-miR-4429 feedback loop promotes cell proliferative and anti-apoptotic abilities in human glioblastoma

Mounting studies have revealed that long non-coding RNA (lncRNA) deleted in lymphocytic leukemia 1 (DLEU1) positively regulated the initiation and development of various human malignant tumors. Nevertheless, the function and mechanism of DLEU1 in human glioblastoma multiforme (GBM) remain elusive and ill-defined. The current study was designed to highlight the functional role and disclose the underlying molecular mechanism by which DLEU1 regulated GBM development. We found that DLEU1 was up-regulated in GBM and DLEU1 knockdown significantly inhibited GBM cell proliferation and induced apoptosis. As predicted by bioinformatics analysis and validated in mechanistic assays, SP1 could bind to the promoter region of DLEU1 to activate DLEU1 transcription. Additionally, miR-4429 was verified as a target gene of DLEU1 and negatively modulated by DLEU1. More importantly, miR-4429 overexpression repressed the mRNA and protein levels of SP1 via binding to the 3'UTR of SP1. Overexpression of SP1 or miR-4429 inhibitor could partly abolish the effect of DLEU1 knockdown on cell viability and apoptosis in GBM. Accordingly, our experimental data revealed that SP1-DLEU1-miR-4429 formed a feedback loop to promote GBM development, providing a new evidence for the role of DLEU1 in GBM.

Up-regulated long non-coding RNA DUXAP8 promotes cell growth through repressing Krüppel-like factor 2 expression in human hepatocellular carcinoma

Background and aim

Long non-coding RNAs (lncRNAs) are implicated as novel factors in tumorigenesis and tumor progression. Although thousands of lncRNAs have been discovered, only a small portion have been functionally determined in hepatocellular carcinoma (HCC). Here, we aimed to comprehensively analyze differentially expressed lncRNAs, evaluate their clinical significance, and explore the functional roles and underlying mechanism in HCC.

Methods

We identified hundreds of lncRNAs which were dysregulated in HCC tissues through performing integrative analyses using the RNA sequencing data and independent gene microarray data from Gene Expression Omnibus and the Cancer Genome Atlas.

Results

Dysregulated DUXAP8, LINC01116, LINC01138, and PCAT6 are significantly associated with HCC patients' poor outcomes. Further experimental validation revealed that down-regulation of lncRNA DUXAP8 inhibited HCC cells proliferation and colony formation ability. Mechanistically, DUXAP8 repressed tumor suppressor KLF2 transcription through interacting with histone-lysine N-methyltransferase enzyme enhancer of zeste homolog 2.

Conclusion

Taken together, our findings can provide a valuable resource of HCC-associated lncRNAs and new insights into the biological functions of lncRNAs in HCC development.

Comprehensive Analysis of lncRNAs and circRNAs Reveals the Metabolic Specialization in Oxidative and Glycolytic Skeletal Muscles

The biochemical and functional differences between oxidative and glycolytic muscles could affect human muscle health and animal meat quality. However, present understanding of the epigenetic regulation with respect to lncRNAs and circRNAs is rudimentary. Here, porcine oxidative and glycolytic skeletal muscles, which were at the growth curve inflection point, were sampled to survey variant global expression of lncRNAs and circRNAs using RNA-seq. A total of 4046 lncRNAs were identified, including 911 differentially expressed lncRNAs (p < 0.05). The cis-regulatory analysis identified target genes that were enriched for specific GO terms and pathways (p < 0.05), including the oxidation-reduction process, glycolytic process, and fatty acid metabolic. All these were closely related to different phenotypes between oxidative and glycolytic muscles. Additionally, 810 circRNAs were identified, of which 137 were differentially expressed (p < 0.05). Interestingly, some circRNA-miRNA-mRNA networks were found, which were closely linked to muscle fiber-type switching and mitochondria biogenesis in muscles. Furthermore, 44.69%, 39.19%, and 54.01% of differentially expressed mRNAs, lncRNAs, and circRNAs respectively were significantly enriched in pig quantitative trait loci (QTL) regions for growth and meat quality traits. This study reveals a mass of candidate lncRNAs and circRNAs involved in muscle physiological functions, which may improve understanding of muscle metabolism and development from an epigenetic perspective.

LncRNA SNHG16 Promotes Hepatocellular Carcinoma Proliferation, Migration and Invasion by Regulating miR-186 Expression

Long non-coding RNA (lncRNA) and microRNA (miRNA) play an important role in genesis and progression of tumors. The aim of this study was to explore the expression, biological function and molecular mechanism of small nucleolar RNA host gene 16 (SNHG16) in HCC. RT-qPCR was conducted to evaluate the expression level of SNHG16 in HCC tissues and cell lines. Our findings showed for the first time that SNHG16 was up-regulated in HCC tissues and cell lines. The expression of SNHG16 in cancer tissues was highly correlated with tumor size, TNM stage, ALT expression level and HBV DNA level. Moreover, cell proliferation, migration and invasion were detected by CCK-8 assay, transwell migration assay and transwell invasion assay, respectively. Xenograft tumor experiment was used to determine the biological function of SNHG16 in vivo. As revealed by our data, SNHG16 accelerated the proliferation, migration and invasion of HCC cell. SNHG16 facilitated tumor formation in vivo. Next, the relationship between SNHG16, miR-186 and ROCK1 were analyzed using bioinformatics analysis, qRT-PCR, luciferase reporter assay and western blot. Further molecular mechanism studies reported that the expression of SNHG16 was negatively correlated with the level of miR-186 and SNHG16 directly bound to miR-186. SNHG16 and miR-186 repressed each other. Notably, rescue experiments were conducted and showed that miR-186 reversed the effect of SNHG16 on cell. Taken together, SNHG16 promoted HCC cell proliferation, migration and invasion by functioning as a competitive endogenous RNA (ceRNA) to negatively regulate miR-186 expression. Our data suggested that SNHG16 might be a potential biomarker and a new therapeutic target for HCC.

Down-regulated lncRNA SLC25A5-AS1 facilitates cell growth and inhibits apoptosis via miR-19a-3p/PTEN/PI3K/AKT signalling pathway in gastric cancer

Mounting evidence has illustrated the vital roles of long non-coding RNAs (lncRNAs in gastric cancer (GC). Nevertheless, the majority of their roles and mechanisms in GC are still largely unknown. In this study, we investigate the roles of lncRNA SLC25A5-AS1 on tumourigenesis and explore its potential mechanisms in GC. The results showed that the expressions of SLC25A5-AS1 in GC were significantly lower than that of adjacent normal tissues, which were significantly associated with tumour size, TNM stage and lymph node metastasis. Moreover, SLC25A5-AS1 could inhibit GC cell proliferation, induce G1/G1 cell cycle arrest and cell apoptosis in vitro, as well as GC growth in vivo. Dual-luciferase reporter assay confirmed the direct interaction between SLC25A5-AS1 and miR-19a-3p, rescue experiment showed that co-transfection miR-19a-3p mimics and pcDNA-SLC25A5-AS1 could partially restore the ability of GC cell proliferation and the inhibition of cell apoptosis. The mechanism analyses further found that SLC25A5-AS1 might act as a competing endogenous RNAs (ceRNA), which was involved in the derepression of PTEN expression, a target gene of miR-19a-3p, and regulate malignant phenotype via PI3K/AKT signalling pathway in GC. Taken together, this study indicated that SLC25A5-AS1 was down-regulated in GC and functioned as a suppressor in the progression of GC. Moreover, it could act as a ceRNA to regulate cellular behaviours via miR-19a-3p/PTEN/PI3K/AKT signalling pathway. Thus, SLC25A5-AS1 might be served as a potential target for cancer therapeutics in GC.

LincK contributes to breast tumorigenesis by promoting proliferation and epithelial-to-mesenchymal transition

BACKGROUND

Increasing evidence has demonstrated that mesenchymal stem cells (MSCs) play a role in the construction of tumor microenvironments. Co-culture between tumor cells and MSCs provides an easy and useful platform for mimicking tumor microenvironments and identifying the important members involved in tumor progress. The long non-coding RNAs (lncRNAs) have been shown to regulate different tumorigenic processes. In this study, we aimed to examine functional lncRNA deregulations associated with breast cancer malignancy instigated by MSC-MCF-7 co-culture.

METHODS

The microarrays were used to profile the expression changes of lncRNAs in MCF-7 cells during epithelial-mesenchymal transition (EMT) induced by co-culture with MSCs. We found that an intergenic lncRNA KB-1732A1.1 (termed LincK, partly overlapped with GASL1) was significantly elevated. To investigate the biological function of LincK, the expression of EMT markers, cell migration, invasion, proliferation, and colony formation were evaluated in vitro and xenograft assay in nude mice were performed in vivo. Furthermore, we detected LincK expression in clinical samples using RNAscope® technology and verified aberrant expression of LincK in breast cancer data sets from The Cancer Genome Atlas (TCGA) by bioinformatic analysis. The underlying mechanisms of LincK were investigated using mRNA microarray analyses, Western blot, RNA pull down, and RNA immunoprecipitation.

RESULTS

LincK induced an EMT progress in breast cancer cells (BCC) MCF-7, MDA-MB-453, and MDA-MB-231. The depletion of LincK decreased the growth, migration, and invasion in BCC, whereas the overexpression of LincK exerted the opposite effects. Moreover, knockdown of LincK repressed tumorigenesis, and ectopic expression of LincK promoted tumor growth in MCF-7 xenograft model. LincK ablation in MDA-MB-231 cells dramatically impaired lung metastasis when incubated intravenously into nude mice. Further, LincK was frequently elevated in breast cancer compared with normal breast tissue in clinical samples. Mechanistically, LincK may share common miRNA response elements with PBK and ZEB1 and regulate the effects of miR-200 s.

CONCLUSION

LincK plays a significant role in regulating EMT and tumor growth and could be a potential therapeutic target in breast cancer.

Identification of the biological affection of long noncoding RNA BC200 in Alzheimer's disease

BC200 is a long noncoding RNA expressed at high levels in the Alzheimer's disease (AD), and blocking of BC200 by siRNA is assumed to be an effective method for various disease therapy. We have established an AD cell model overexpressing amyloid β-peptide (Aβ)1-42 to observe the effects of BC200 on the cell viability and apoptosis, and to investigate the associated underlying mechanisms. Efficient knockdown and overexpression of BC200 were established using BC200 siRNA and BC200 mimics, respectively. Cell viability following BC200 knockdown and overexpression was assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyltetrazolium bromide assay, and cell apoptosis was monitored by flow cytometry. We successfully established an AD cell model overexpressing Aβ1-42 gene, and reported the results of change of BC200 on Aβ1-42 levels. Knockdown of BC200 significantly suppressed b-site amyloid precursor protein-cleaving enzyme 1 (BACE1) expression, and overexpression of BC200 increased BACE1 expression. Besides, inhibition of BC200 significantly increased cell viability and reduced cell apoptosis in the AD model via directly targeting BACE1, which can be increased by overexpression of BC200. BC200 regulated AD cell viability and apoptosis via targeting BACE1, and it may be one of the putative target in AD development and provides potential new insights into genetic therapy against AD.

Long noncoding RNA HOTAIR silencing inhibits invasion and proliferation of human colon cancer LoVo cells via regulating IGF2BP2

Colon cancer is one of the most life-threatening malignancies worldwide. Long noncoding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) is a cancer-associated biomarker involved in the metastasis and prognosis of several cancers. However, whether and how HOTAIR affects colon cancer progression is still unclear. Consequently, we used RNA interference to knock down HOTAIR to explore its effects on human colon cancer cells. The dual luciferase reporter gene assay was initially used for testify the regulating relationship between lncRNA HOTAIR and insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2). We determined the expressions of HOTAIR, IGF2BP2, E-cadherin, and vimentin. Meanwhile, cell growth, cycle and apoptosis, migration, and invasion were assayed. LoVo cells were transplanted into nude mice, and tumor formation and microvessel density were evaluated. LncRNA HOTAIR positively regulated IGF2BP2. Besides, the expressions of HOTAIR and E-cadherin and the apoptosis were increased, while the expressions of IGF2BP2 and vimentin, the growth, invasion and migration of LoVo cells, the average tumor weight, and microvessel density value were decreased. Of importance, overexpressed IGF2BP2 could reverse the above impacts. Taken together, the current study indicates that silencing of HOTAIR could inhibit the invasion, proliferation, and migration, and promote apoptosis of colon cancer LoVo cells through suppressing IGF2BP2 and the epithelial-mesenchymal transition.

Feature selection of gene expression data for Cancer classification using double RBF-kernels

BACKGROUND

Using knowledge-based interpretation to analyze omics data can not only obtain essential information regarding various biological processes, but also reflect the current physiological status of cells and tissue. The major challenge to analyze gene expression data, with a large number of genes and small samples, is to extract disease-related information from a massive amount of redundant data and noise. Gene selection, eliminating redundant and irrelevant genes, has been a key step to address this problem.

RESULTS

The modified method was tested on four benchmark datasets with either two-class phenotypes or multiclass phenotypes, outperforming previous methods, with relatively higher accuracy, true positive rate, false positive rate and reduced runtime.

CONCLUSIONS

This paper proposes an effective feature selection method, combining double RBF-kernels with weighted analysis, to extract feature genes from gene expression data, by exploring its nonlinear mapping ability.

LncRNA DLEU1 contributes to colorectal cancer progression via activation of KPNA3

Background

Accumulating evidences show that long noncoding RNAs (lncRNA) play essential roles in the development and progression of various malignancies. However, their functions remains poorly understood and many lncRNAs have not been defined in colorectal cancer (CRC). In this study, we investigated the role of DLEU1 in CRC.

Methods

Quantitative real-time PCR was used to detect the expression of DLEU1 and survival analysis was adopted to explore the association between DLEU1 expression and the prognosis of CRC patients. CRC cells were stably transfected with lentivirus approach and cell proliferation, migration, invasion and cell apoptosis, as well as tumorigenesis in nude mice were performed to assess the effects of DLEU1 in BCa. Biotin-coupled probe pull down assay, RNA immunoprecipitation and Fluorescence in situ hybridization assays were conducted to confirm the relationship between DLEU1 and SMARCA1.

Results

Here we revealed that DLEU1 was crucial for activation of KPNA3 by recruiting SMARCA1, an essential subunit of the NURF chromatin remodeling complex, in CRC. DLEU1 was indispensible for the deposition of SMARCA1 at the promoter of KPNA3 gene. Increased expression of DLEU1 and KPNA3 was observed in human CRC tissues. And higher expression of DLEU1 or KPNA3 in patients indicates lower survival rate and poorer prognosis. DLEU1 knockdown remarkably inhibited CRC cell proliferation, migration and invasion in vitro and in vivo while overexpressing KPNA3 in the meantime reversed it.

Conclusions

Our results identify DLEU1 as a key regulator by a novel DLEU1/SMARCA1/KPNA3 axis in CRC development and progression, which may provide a potential biomarker and therapeutic target for the management of CRC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0873-2) contains supplementary material, which is available to authorized users.

The Prognostic Value of Expression of the Long Noncoding RNA (lncRNA) Small Nucleolar RNA Host Gene 1 (SNHG1) in Patients with Solid Malignant Tumors: A Systematic Review and Meta-Analysis

BACKGROUND The long non-coding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) is expressed in solid malignant tumors. The aim of this systematic review and meta-analysis was to determine whether expression of the lncRNA SNHG1 was associated with prognosis in patients with malignancy. MATERIAL AND METHODS A literature review from Jan 1970 to July 2018 identified publications in the English language. Databases searched included: PubMed, OVID, Web of Science, the Cochrane Database, Embase, EBSCO, Google Scholar. Systematic review and meta-analysis were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The Newcastle-Ottawa Scale (NOS) assessment tool for risk of bias was used. RESULTS Eight publications (570 patients) and eight solid tumors were identified, including osteosarcoma, colorectal cancer, hepatocellular carcinoma, non-small cell lung cancer, esophageal cancer, ovarian cancer, glioma, and gastric cancer. Meta-analysis showed that expression of the lncRNA SNHG1 was significantly correlated with reduced overall survival (OS) (HR=1.917; 95% CI, 1.58-2.31) (P<0.001). Subgroup analysis showed that lncRNA SNHG1 expression was significantly correlated with TNM stage (OR=3.99; 95% CI, 2.48-6.43) and lymph node metastasis (OR=3.12; 95% CI, 1.95-4.98). There were no significant correlations between lncRNA SNHG1 expression and patient gender, tumor subtype, or tumor size. CONCLUSIONS Systematic literature review and meta-analysis identified eight publications that included 570 patients with eight types of solid malignant tumor, and showed that the expression of the lncRNA SNHG1 was significantly associated with worse clinical outcome.

Down-regulation of lncRNA ADAMTS9-AS2 contributes to gastric cancer development via activation of PI3K/Akt pathway

OBJECTIVE

We aimed to investigate the role and regulatory mechanism of lncRNA ADAMTS9-AS2 in the development of gastric cancer.

MATERIALS AND METHODS

The expression of lncRNA ADAMTS9-AS2 in gastric cancer tissues and cells was detected. According to the expression level of ADAMTS9-AS2, survival analysis for patients with gastric cancer was performed. In addition, SGC-7901 cells were transfected with pc-ADAMTS9-AS2, si-ADAMTS9-AS2 and scramble RNA (control) to investigate the effects of ADAMTS9-AS2 on cell proliferation, migration, invasion and apoptosis. Besides, the expression levels of key molecules involved in PI3K/Akt pathway were detected.

RESULTS

Results showed that lncRNA ADAMTS9-AS2 was significantly down-regulated in gastric cancer tissues and cells. Decreased expression of lncRNA ADAMTS9-AS2 was associated with poor prognosis in patients with gastric cancer. In comparison with control group, the SGC-7901 cell viability and the number of colony, migrated or invaded SGC-7901 cells of pc-ADAMTS9-AS2 group were significantly decreased while markedly increased in si-ADAMTS9-AS2 group. The percentage of apoptotic SGC-7901 cells in pc-ADAMTS9-AS2 group was significantly increased, while significantly decreased in si-ADAMTS9-AS2 group. Additionally, the expressions of p-PI3K and p-Akt were significantly down-regulated in pc-ADAMTS9-AS2 group compared with control group, while up-regulated in si-ADAMTS9-AS2 group. Furthermore, compared with si-ADAMTS9-AS2 group, treatment of an PI3K inhibitor LY294002 markedly reversed the effects of suppression of ADAMTS9-AS2 alone on SGC-7901 cells by inhibiting cell viability, colony-forming ability, migration, invasion, and increasing apoptosis.

CONCLUSIONS

Our results indicate that overexpression of ADAMTS9-AS2 may inhibit gastric cancer cell proliferation, suppress cancer cell migration and invasion, and induce cell apoptosis. Activation of PI3K/Akt pathway may be a key regulatory mechanism of ADAMTS9-AS2 in gastric cancer.

Up-regulation of long noncoding RNA M26317 correlates with tumor progression and poor prognosis in gastric cancer

To investigate the expression and clinical significance of long noncoding RNA (lncRNA) in gastric cancer, we applied microarray analysis to obtain expression profiles of protein-coding genes and lncRNAs in tumor and paired adjacent nontumor tissues. We found that 41 lncRNAs were up-regulated and 31 lncRNAs were down-regulated more than 2-fold in gastric cancer versus noncancerous tissues (ratio >2.0, P < .01). We established a coexpression network of the differentially expressed lncRNAs and targeted coding genes that included 17 lncRNAs and 16 coding genes. Because the results of microarray analysis showed that lncRNA M26317 was up-regulated in gastric cancer tissues, we examined the expression level of M26317 in 103 gastric cancer tissues by reverse-transcription polymerase chain reaction and 436 gastric cancer tissues by in situ hybridization. Our data confirmed that M26317 was up-regulated in gastric cancer tissues. Moreover, expression of M26317 correlated with patient age, size of tumor, Lauren's classification, depth of invasion, lymph node and distant metastasis, TNM stage, and poor prognosis (P < .05), but was not associated with sex, location of tumor, and differentiation (P > .05). M26317 may have an important role in malignant transformation and metastasis of gastric cancer.

LncRNA16 is a potential biomarker for diagnosis of early-stage lung cancer that promotes cell proliferation by regulating the cell cycle

Early diagnosis of lung cancer greatly reduces mortality; however, the lack of suitable plasma biomarkers presents a major obstacle. Recent studies showed that long noncoding RNAs (lncRNAs) played important roles in cancer initiation and development. Here, we identified differentially expressed lncRNAs in 20 lung cancer samples by using custom designed microarray and evaluated their expression in 118 lung cancer samples by real-time PCR (qRT-PCR). lncRNA16 (ENST00000539303) expression was significantly higher in lung cancer tissues (80/118) than in adjacent matched normal tissues. Importantly, this increase was similar to that in plasma (53/84) of lung cancer patients, including early stage. The role of lncRNA16 in lung cancer was studied in vitro and in vivo by using the lung cancer cell lines and xenograft mouse models. The results reveal that knockdown of lncRNA16 inhibited proliferation of PC9 cells in vitro and also inhibited tumor growth in xenograft mouse models. Overexpression of lncRNA16 promoted proliferation of A549 cells in vitro and also promoted tumor growth in xenograft mouse models. Specifically, we showed that lncRNA16 promoted G2/M transition by regulating cyclin B1 transcription. Together, our findings suggest that lncRNA16 is a promising biomarker suitable for early diagnosis of lung cancer, and a potential target for lung cancer treatment.

LncRNA PCAT-1 promotes tumour growth and chemoresistance of oesophageal cancer to cisplatin

Oesophageal cancer (OC) is one of the most fatal malignancies in the world, and chemoresistance restricts the therapeutic outcome of OC. Long noncoding RNA (lncRNA) was reported to play roles in multiple cancer types. Yet, the function of lncRNA in chemoresistance of OC has not been reported. A lncRNA gene, PCAT-1, showed higher expression in OC tissues, especially higher in secondary OC compared with normal mucosa tissues. Overexpression of PCAT-1 increased the proliferation rate and growth of OC cells. Inhibition of PCAT-1 decreased proliferation and growth of OC cells, and increased cisplatin chemosensitivity. In a mouse OC xenograft model, PCAT-1 inhibition repressed OC growth in vivo. Therefore, PCAT-1 may potentially serve as a therapeutic target for treating OC. PCAT-1 promotes development of OC and represses the chemoresistance of OC to cisplatin, and silencing of PCAT-1 may be a therapeutic strategy for treating OC.

Long Non-coding RNAs, Novel Culprits, or Bodyguards in Neurodegenerative Diseases

Long non-coding RNA (lncRNA) is a kind of non-coding RNA (ncRNA), with a length of 200 nt to 100 kb, that lacks a significant open reading frame (ORF) encoding a protein. lncRNAs are widely implicated in various physiological and pathological processes, such as epigenetic regulation, cell cycle regulation, cell differentiation regulation, cancer, and neurodegenerative diseases, through their interactions with chromatin, protein, and other RNAs. Numerous studies have suggested that lncRNAs are closely linked with the occurrence and development of a variety of diseases, especially neurodegenerative diseases, of which the etiologies are complicated and the underlying mechanisms remain elusive. Determining the roles of lncRNA in the pathogenesis of neurodegenerative diseases will not only deepen understanding of the physiological and pathological processes that occur in those diseases but also provide new ideas and solutions for their diagnosis and prevention. This review aims to highlight the progress of lncRNA research in the pathological and behavioral changes of neurodegenerative diseases. Specifically, we focus on how lncRNA dysfunctions are involved in the pathogenesis of Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis.

LncRNA Gas5 acts as a ceRNA to regulate PTEN expression by sponging miR-222-3p in papillary thyroid carcinoma

Accumulating evidence demonstrates that the long non-coding RNA Growth Arrest-Specific 5 (Gas5) has practical significance in cancer progression and metastasis. However, its role and function in papillary thyroid carcinoma (PTC) remains unknown. In this study, we aimed to explore the potential involvement of Gas5 in papillary thyroid carcinogenesis and to highlight the emerging roles of ceRNAs in the biological regulation of PTC cells. The results suggested that Gas5 was markedly downregulated in both PTC tissues and PTC cell lines. Over-expression of Gas5 remarkably suppressed PTC cells proliferation in vitro and inhibited the growth of tumor cells in vivo likewise. Furthermore, Gas5 was identified as a target of miR-222-3p which was aberrantly high in PTC cells. Enhanced expression of miR-222-3p promoted the proliferation of PTC cells while knocking down miR-222-3p could inhibit it. The advanced effects of miR-222-3p on the proliferation of PTC cells could be partly reversed by the upregulation of Gas5 expression. Furthermore, we validated that Gas5 increased the protein level of the PTEN, one of miR-222-3p’s targets, which further activated PTEN/AKT pathway. Taken together, our study identified a tumor suppressive role of Gas5 in PTC cells acting as a ceRNA, effectively becoming a sink for miR-222-3p, modulating the expression of PTEN, which lead to PTEN/AKT pathway activation and proliferation suppression. This finding may offer a new potential therapeutic strategy for PTC.

LncRNA MT1JP functions as a tumor suppressor by interacting with TIAR to modulate the p53 pathway

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play important roles in transcriptional regulation, whereas the extent to which the lncRNAs also function at the posttranscriptional level is less known. In the present study, we report a lncRNA named MT1JP which acts as a tumor suppressor through a posttranscriptional mechanism. We found that MT1JP is differentially expressed in tumor tissues by analyzing data from a customized microarray applied to 76 pairs of matched normal and cancer tissue samples. By associating with the RNA-binding protein TIAR, MT1JP enhanced the translation of the master transcription factor p53, thereby regulating a series of pathways involving p53, such as the cell cycle, apoptosis and proliferation. When MT1JP was down-regulated, the protein level of p53 declined, which in turn accelerated cell deterioration and tumor formation. Moreover, differential expression of MT1JP in cancerous and normal tissues suggests that it may be a promising prognostic marker and a therapeutic target. Taken together, we identified MT1JP as a critical factor in restraining cell transformation by modulating p53 translation through interactions with TIAR, and this finding is likely to shed new light on future investigations about posttranscriptional or translational effects of lncRNAs during cell transformation.

Prognostic value of long non-coding RNA PVT1 as a novel biomarker in various cancers: a meta-analysis

Background

Plasmacytoma variant translocation 1 (PVT1) has recently been reported to be aberrantly expressed and serves as a prognostic biomarker in many types of cancers. However, its prognostic significance remains controversial. Here, we conducted a meta-analysis to investigate the prognostic value of PVT1 expression in cancers.

Results

A total of 2109 patients from 20 studies were included. The results showed that elevated PVT1 expression predicted a poor outcome for overall survival (OS) in nine types of cancers (HR = 1.40, 95% CI: 1.21–1.59). Subgroup analysis indicated that there was a significant association between PVT1 overexpression and poor OS of patients with gastric cancer, gynecology cancer and lung cancer. Furthermore, we also found a negative significant relationship between PVT1 expression and disease-free survival (HR = 1.83, 95% CI: 1.39–2.27), progression-free survival (HR = 1.63, 95% CI: 1.34–1.93) and recurrence-free survival (HR = 1.74, 95% CI: 1.01–2.47). In addition, the level of PVT1 expression was positively related to tumor size, TNM stage, lymph node metastasis and distant metastases.

Materials and Methods

A systematic search was performed through the PubMed, EMBASE, Web of Science, Ovid and Cochrane library databases for eligible studies on prognostic value of PVT1 in cancers from inception up to June, 2017. The pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the association between PVT1 expression and clinical outcomes.

Conclusions

PVT1 expression positively related to tumor size, TNM stages, lymph node metastasis and distant metastases, and served as a prognostic biomarker in different types of cancers.

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

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

Down-regulation of the long noncoding RNA-HOX transcript antisense intergenic RNA inhibits the occurrence and progression of glioma

This study aims to explore the role of long noncoding RNA (lncRNA)-HOX transcript antisense intergenic RNA (HOTAIR) in the occurrence and progression of glioma. Fresh glioma and normal brain tissues were classified into a glioma group (n = 67) and a normal group (n = 64) respectively. U87 cells were assigned into the blank, sh-NC, and sh-HOTAIR groups. Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to determine HOTAIR expression. Cell proliferation, cell cycle and cell apoptosis rates were detected by cell counting kit-8 (CCK-8) and flow cytometry (FCM). Scratch test and transwell assay were conducted for cell migration and invasion. Orthotopic glioma tumor model in nude mice was established by inoculating tumor cell suspension. Hematoxylin-Eosin (HE) staining was used to observe the growth and invasion of orthotopic glioma tumors. The expression of HOTAIR and cell viability was found to be lowest in the sh-HOTAIR group among the three groups. The sh-HOTAIR group exhibited a higher apoptotic rate and lower number of cell migration compared with the blank and sh-NC groups. Additionally, the speed of wound healing was slower, the migration distance decreased and the survival time of nude mice was extended in the sh-HOTAIR compared to the other groups. Moreover, the sh-HOTAIR group demonstrated reduced lesion sizes and inflammation, no convulsions or hemiplegia and lesser number of satellite metastases. Our findings support that down-regulation of HOTAIR could inhibit cell proliferation, promote cell apoptosis as well as suppress cell invasion and migration in the progression of glioma.

Mesenchymal Stem Cells Promote Hepatocarcinogenesis via lncRNA-MUF Interaction with ANXA2 and miR-34a

Accumulating evidence suggests that cancer-associated mesenchymal stem cells (MSC) contribute to the development and metastasis of hepatocellular carcinoma (HCC). Aberrant expression of long noncoding RNAs (lncRNA) has been associated with these processes but cellular mechanisms are obscure. In this study, we report that HCC-associated mesenchymal stem cells (HCC-MSC) promote epithelial-mesenchymal transition (EMT) and liver tumorigenesis. We identified a novel lncRNA that we termed lncRNA-MUF (MSC-upregulated factor) that is highly expressed in HCC tissues and correlated with poor prognosis. Depleting lncRNA-MUF in HCC cells repressed EMT and inhibited their tumorigenic potential. Conversely, lncRNA-MUF overexpression accelerated EMT and malignant capacity. Mechanistic investigations showed that lncRNA-MUF bound Annexin A2 (ANXA2) and activated Wnt/β-catenin signaling and EMT. Furthermore, lncRNA-MUF acted as a competing endogenous RNA for miR-34a, leading to Snail1 upregulation and EMT activation. Collectively, our findings establish a lncRNA-mediated process in MSC that facilitates hepatocarcinogenesis, with potential implications for therapeutic targeting. Cancer Res; 77(23); 6704-16. ©2017 AACR.

Distinct Hippocampal Expression Profiles of Long Non-coding RNAs in an Alzheimer's Disease Model

Alzheimer's disease (AD), the most prevalent form of dementia worldwide, is a complex neurodegenerative disease characterized by the progressive loss of memory and other cognitive functions. The pathogenesis of AD is not yet completely understood. Although long non-coding RNAs (lncRNAs) have recently been shown to play a role in AD pathogenesis, the specific influences of lncRNAs in AD remain largely unknown; in particular, hippocampal lncRNA expression profiles in AD rats are lacking. In this study, microarray analysis was performed to investigate the hippocampal expression patterns of dysregulated lncRNAs in a rat model of AD. A total of 315 lncRNAs and 311 mRNAs were found to be significantly dysregulated in the AD model (≥2.0 fold, p < 0.05). Then, quantitative real-time PCR was used to validate the expression of selected lncRNAs and mRNAs. Bioinformatics tools and databases were employed to explore the potential lncRNA functions. This is the first study to comprehensively identify dysregulated hippocampal lncRNAs in AD and to demonstrate the involvement of different lncRNA expression patterns in the hippocampal pathogenesis of AD. This information will enable further research on the pathogenesis of AD and facilitate the development of novel AD therapeutics targeting lncRNAs.

Identification of dysregulated lncRNAs profiling and metastasis-associated lncRNAs in colorectal cancer by genome-wide analysis

The colorectal cancer (CRC) is one of the leading causes of cancer‐related death worldwide, but the pathogenesis of CRC remains not well‐known. Increasing studies have highlighted the critical roles of long noncoding RNAs (lncRNAs) in tumorigenesis and cancer cells metastasis, however, the expression pattern, biological roles of lncRNAs, and the mechanisms responsible for their function in CRC remain elusive. In this study, we performed a genome‐wide comprehensive analysis of lncRNAs profiling and clinical relevance to identify novel lncRNAs for the further study in CRC. RNA sequencing and microarray data obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were annotated and analyzed to find differentially expressed lncRNAs in CRC. Analysis of these datasets revealed that hundreds of lncRNAs expression are dysregulated in CRC tissues when compared with normal tissues. By genomic variation analyses, we identified that some of these lncRNAs dysregulation is associated with the copy number amplification or deletion. Moreover, many lncRNAs expression levels are significantly associated with CRC patients overall and recurrence‐free survivals, such as H19, LEF1‐AS1, and RP11‐296E3.2. Furthermore, we identified one liver metastasis‐associated lncRNA termed LUCAT1 in CRC by analyzing lncRNAs expression profiles in the CRC tissues from patients with liver metastasis compared with the CRC tissues without metastasis. Finally, loss‐of‐function assays determined that knockdown of LUCAT1 could impair CRC cells invasion. Taken together, aberrantly expressed lncRNAs may play critical roles in the development and liver metastasis of CRC, and our findings may provide useful resource for identification of novel biomarkers of CRC.

Crosstalk in competing endogenous RNA network reveals the complex molecular mechanism underlying lung cancer

We investigated the transcriptional mechanism underlying lung cancer development. RNA sequencing analysis was performed on blood samples from lung cancer cases and healthy controls. Differentially expressed microRNAs (miRNAs), circular RNAs (circRNAs), mRNAs (genes), and long non-coding RNAs (lncRNA) were identified, followed by pathway enrichment analysis. Based on miRNA target interactions, a competing endogenous network was established and significant nodes were screened. Differentially expressed transcriptional factors were retrieved from the TRRUST database and the transcriptional factor regulatory network was constructed. The expression of 59 miRNAs, 18,306 genes,232 lncRNAs, and 292 circRNAs were greatly altered in patients with lung cancer. miRNAs were closely associated with cancer-related pathways, such as pathways in cancer, colorectal cancer, and transcriptional misregulation in cancer. Two novel pathways, olfactory transduction and neuroactive ligand-receptor interactions, were significantly enriched by differentially expressed genes. The competing endogenous RNA network revealed 5 hub miRNAs. Hsa-miR-582-3p and hsa-miR-582-5p were greatly enriched in the Wnt signaling pathway. Hsa-miR-665 was closely related with the MAPK signaling pathway. Hsa-miR-582-3p and hsa-miR-582-5p were also present in the TF regulatory network. Transcriptional factors of WT1 (wilms tumor 1) and ETV1 (ETS variant 1) were regulated by hsa-miR-657 and hsa-miR-582-5p, respectively, and controlled androgen receptor gene expression. miR-582-5p, miRNA-582-3p, and miR-657 may play critical regulatory roles in lung tumor development. Our work may explore new mechanism of lung cancer and aid the development of novel therapy.

The long noncoding RNA SNHG1 promotes tumor growth through regulating transcription of both local and distal genes

Increasing evidence indicates that long noncoding RNAs (lncRNAs) have important roles in various physiological processes and dysfunction of lncRNAs could be a prevalent cause in human diseases. Here we functionally characterized the nuclear-enriched lncRNA SNHG1, which is highly expressed in multiple types of cancer. We also provide evidence that SNHG1 promotes cancer cell growth by regulating gene expression both in cis and in trans. SNHG1 was involved in the AKT signaling pathway as it promotes the neighboring transcription of the protein-coding gene SLC3A2 in cis by binding the Mediator complex to facilitate the establishment of enhancer-promoter interaction. In trans, SNHG1 directly interacted with central domain of FUBP1 and antagonize the binding of FBP-interacting repressor to FUBP1, thereby coordinating the expression of the oncogene MYC. Collectively, our findings demonstrate that lncRNA SNHG1 can function both in cis and in trans with distinct mechanisms to regulate transcription, promoting tumorigenesis and cancer progression.

Systemically identifying and prioritizing risk lncRNAs through integration of pan-cancer phenotype associations

LncRNAs have emerged as a major class of regulatory molecules involved in normal cellular physiology and disease, our knowledge of lncRNAs is very limited and it has become a major research challenge in discovering novel disease-related lncRNAs in cancers. Based on the assumption that diverse diseases with similar phenotype associations show similar molecular mechanisms, we presented a pan-cancer network-based prioritization approach to systematically identify disease-specific risk lncRNAs by integrating disease phenotype associations. We applied this strategy to approximately 2800 tumor samples from 14 cancer types for prioritizing disease risk lncRNAs. Our approach yielded an average area under the ROC curve (AUC) of 80.66%, with the highest AUC (98.14%) for medulloblastoma. When evaluated using leave-one-out cross-validation (LOOCV) for prioritization of disease candidate genes, the average AUC score of 97.16% was achieved. Moreover, we demonstrated the robustness as well as the integrative importance of this approach, including disease phenotype associations, known disease genes and the numbers of cancer types. Taking glioblastoma multiforme as a case study, we identified a candidate lncRNA gene SNHG1 as a novel disease risk factor for disease diagnosis and prognosis. In summary, we provided a novel lncRNA prioritization approach by integrating pan-cancer phenotype associations that could help researchers better understand the important roles of lncRNAs in human cancers.

Clinical significance and prospective molecular mechanism of MALAT1 in pancreatic cancer exploration: a comprehensive study based on the GeneChip, GEO, Oncomine, and TCGA databases

Purpose

Long noncoding RNAs (lncRNAs) are known to function as regulators in the development and occurrence of various tumors. MALAT1 is a highly conserved lncRNA and has vital functions in diverse tumors, including pancreatic cancer (PC). However, the underlying molecular regulatory mechanism involved in the occurrence and development of PC remains largely unknown. Thus, it is important to explore MALAT1 in PC and elucidate its function, which might offer a new perspective for clinical diagnosis and therapy.

Methods

First, we used the Gene Expression Omnibus, Oncomine, and The Cancer Genome Atlas databases to determine the clinical diagnostic and prognostic values of MALAT1. We next used our own GeneChip and The Cancer Genome Atlas database to collect the possible target genes of MALAT1 and further utilized a bioinformatics analysis to explore the underlying significant pathways that might be crucial in PC. Finally, we identified several key target genes of MALAT1 and hope to offer references for future research.

Results

We found that the expression of MALAT1 was significantly elevated in patients with PC. A receiver operating characteristics curve analysis showed a moderate diagnostic value (area under the curve =0.75, sensitivity =0.66, specificity =0.72). A total of 224 important overlapping genes were collected, and six hub genes (CCND1, MAPK8, VEGFA, FOS, CDH1, and HSP90AA1) were identified, of which CCND1, MAPK8, and VEGFA, are important genes in PC. Several pathways, including the mTOR signaling pathway, pathways in cancer, and the MAPK signaling pathway, were suggested to be the vital MALAT1 pathways in PC.

Conclusion

MALAT1 is suggested to be a promising diagnostic biomarker in PC. Six hub genes (CCND1, MAPK8, VEGFA, FOS, CDH1, and HSP90AA1), and specifically CCND1, MAPK8, and VEGFA, might be key MALAT1 target genes in PC. Due to their possible clinical significance in PC, several pathways, such as the mTOR signaling pathway, pathways in cancer, and the MAPK signaling pathway, are worthy of further study.

Long noncoding RNA LINC01186, regulated by TGF-β/SMAD3, inhibits migration and invasion through Epithelial-Mesenchymal-Transition in lung cancer

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) are crucial regulators of the Epithelial-Mesenchymal-Transition (EMT). TGF-β signaling is a major inducer of EMT and can facilitate lung cancer metastasis. However, the role of lncRNAs in this process remains largely unknown. Here, we have identified 291 lncRNAs which were differentially expressed in lung cancer tissues compared with adjacent normal tissues. Of these, the gene body or vicinity of 19 transcripts were also bound by SMAD3. The expression of LINC01186 was significantly decreased in A549 cells treated with TGF-β1. Furthermore, LINC01186 was stably down-regulated in lung cancer tissues compared with normal tissues in TCGA data sets and another published lung cancer data sets. The bioinformatics analysis suggested that LINC01186 was associated with TGF-β and might participate in EMT process. Moreover, knocking-down LINC01186 promoted cell migration and invasion, whereas, LINC01186 overexpression prevented cell metastasis. Importantly, LINC01186 expression was regulated by SMAD3. And LINC01186 affected several EMT markers expression. These findings suggest that LINC01186, a mediator of TGF-β signaling, can play a significant role in the regulation of EMT and lung cancer cell migration and invasion.

LncRNA GAS5 inhibits proliferation and progression of prostate cancer by targeting miR-103 through AKT/mTOR signaling pathway

In prior research, evidence has been found for a relation between low exposure of long non-coding RNAs (lncRNAs) and prostate tumor genesis. This study aims to clarify the underlying mechanisms of lncRNA GAS5 in prostate cancer (PCa). In total, 118 pairs of PCa tissues and matched adjacent non-tumor tissues were collected. Additionally, lncRNA GAS5 exposure levels were determined using RT-PCR and in situ hybridization. In addition, dual-luciferase report assay was performed to verify the target effect of lncRNA GAS5 on miR-103. The exposure levels of the proteins related to the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) axis, including AKT, mTOR, and S6K1, were measured by western blot PC3 cells infected with lncRNA GAS5 mimic; lncRNA GAS5 siRNA; or a combination of lncRNA and miR-103. The proliferation, invasion, and migration ability of PC3 cells after being infected were tested by MTT assay, wound healing assay, and transwell assays. Finally, nude mouse xenograft models were used to measure lncRNA GAS5 effects on prostate tumor growth in vivo. The lncRNA GAS5 levels were reduced significantly in the PCa tissues and cell lines (P < 0.05). A low exposure of lncRNA GAS5 caused AKT/mTOR signaling pathway activation in PC3 cells (P < 0.05). In addition, over-exposure of lncRNA GAS5 was proven to significantly decelerate PCa cell progression in vitro and tumor growth in vivo through inactivating the AKT/mTOR signaling pathway (P < 0.05). This study proves that lncRNA GAS5 plays a significant role in the decelerating PCa development via mediating the AKT/mTOR signaling pathway through targeting miR-103.

Long noncoding RNA MALAT1 can serve as a valuable biomarker for prognosis and lymph node metastasis in various cancers: a meta-analysis

Background

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a newly discovered long intergenic noncoding RNA (lincRNA), has been reported to be aberrantly expressed in various cancers, and may serve as a novel potential biomarker for cancer prognosis. This meta-analysis was conducted to investigate the effects of MALAT1 on cancer prognosis and lymph node metastasis.

Methods

A quantitative meta-analysis was performed using a systematic search of PubMed, Medline and Web of Science databases to identify eligible papers on prognostic value of MALAT1 in cancers. The pooled hazard ratios (HRs) or odds ratios (OR) with a 95 % confidence interval (95 % Cl) were calculated to evaluate its prognostic value.

Results

A total of 2094 patients from 17 studies between 2003 and 2016 were included. The results revealed that elevated MALAT1 expression was significantly associated with poor overall survival (OS) in 11 types of cancers (HR = 1.91, 95 % CI 1.49–2.34). Furthermore, subgroup analysis indicated that region of study (Germany, Japan or China), cancer type (digestive system cancers, urinary system cancers or respiratory system cancers) and sample size (more or less than 100) did not alter the significant predictive value of MALAT1 in OS from various types of cancer. In addition, upregulation of MALAT1 expression was significantly associated with poor disease-free survival (HR = 2.29, 95 % CI 1.24–3.35), and recurrence-free survival (HR = 2.09, 95 % CI 0.81–3.37). The results showed that the incidence of lymph node metastasis was higher in high MALAT1 expression group than that in low MALAT1 expression group (OR = 1.67, 95 % CI 1.30–2.15).

Conclusions

This meta-analysis revealed that elevated MALAT1 expression may serve as a novel predictive biomarker for poor survival and lymph node metastasis in different types of cancer.