Long non-coding RNA Loc554202 induces apoptosis in colorectal cancer cells via the caspase cleavage cascades

LncRNA LUESCC promotes esophageal squamous cell carcinoma by targeting the miR-6785-5p/NRSN2 axis

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent gastrointestinal malignancies with high mortality worldwide. Emerging evidence indicates that long noncoding RNAs (lncRNAs) are involved in human cancers, including ESCC. However, the detailed mechanisms of lncRNAs in the regulation of ESCC progression remain incompletely understood. LUESCC was upregulated in ESCC tissues compared with adjacent normal tissues, which was associated with gender, deep invasion, lymph node metastasis, and poor prognosis of ESCC patients. LUESCC was mainly localized in the cytoplasm of ESCC cells. Knockdown of LUESCC inhibited cell proliferation, colony formation, migration, and invasion in vitro and suppressed tumor growth in vivo. Mechanistic investigation indicated that LUESCC functions as a ceRNA by sponging miR-6785-5p to enhance NRSN2 expression, which is critical for the malignant behaviors of ESCC. Furthermore, ASO targeting LUESCC substantially suppressed ESCC both in vitro and in vivo. Collectively, these data demonstrate that LUESCC may exerts its oncogenic role by sponging miR-6785-5p to promote NRSN2 expression in ESCC, providing a potential diagnostic marker and therapeutic target for ESCC patients.

Crosstalk between long non-coding RNAs and p53 signaling pathway in colorectal cancer: A review study

Colorectal cancer (CRC) is one of the most prevalent malignancies worldwide and the third leading cause of cancer-related fatalities. Long non-coding RNAs (lncRNAs) are key regulators of diverse physiological processes and are dysregulated in a wide range of pathophysiological circumstances such as CRC. Studies revealed that aberrant expressions of lncRNAs clearly modulate the expression level of p53 gene in CRC, thereby transactivating multiple downstream pathways. P53 is regarded as a crucial tumor suppressor gene which promotes cell-cycle arrest, DNA repair, senescence or apoptosis in response to cellular stresses. P53 is also mutated in CRC as well as various types of human malignancies. Therefore, lncRNAs interact with the p53 signaling pathway in numerus ways and significantly influence CRC-related processes. The current findings in the investigation of the crosstalk between lncRNAs and the P53 pathway in controlling CRC carcinogenesis, tumor progression, and therapeutic resistance are summarized in the this review. A deeper knowledge of CRC carcinogenesis may also have implications in CRC prevention and treatment through more research.

MIR31HG, a potential lncRNA in human cancers and non-cancers

Long non-coding RNAs have recently attracted considerable attention due to their aberrant expression in human diseases. LncMIR31HG is a novel lncRNA that is abnormally expressed in multiple diseases and implicated in various stages of disease progression. A large proportion of recent studies have indicated that MIR31HG has biological functions by triggering various signalling pathways in the pathogenesis of human diseases, especially cancers. More importantly, the abnormal expression of MIR31HG makes it a potential biomarker in diagnosis and prognosis, as well as a promising target for treatments. This review aims to systematically summarize the gene polymorphism, expression profiles, biological roles, underlying mechanisms, and clinical applications of MIR31HG in human diseases.

CDKN2B-AS1 as a novel therapeutic target in cancer: Mechanism and clinical perspective

Long non-coding RNAs (lncRNA) have been identified as essential components having considerable modulatory impactson biological activities through altering gene transcription, epigenetic changes, and protein translation. Cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1), a recently discovered lncRNA, was shown to be substantially elevated in various cancers.Furthermore, via modulation ofvarious signalingaxes, it is effectively connected to the control of critical cancer-associatedbiological pathways likecell proliferation, apoptosis, cell cycle, epithelial-mesenchymal transition(EMT), invasion, and migration. Considering the crucial functions ofCDKN2B-AS1in cancer onset and development, this lncRNA offers immense therapeutic implications for usage as a new diagnostic or treatment approach. In this article, we evaluate the most recent discoveries made into the functions of the lncRNA CDKN2B-AS1 in cancer, in addition to its prospect asbeneficial properties,prognostic anddiagnostic biomarkersin the cancer-related treatment, emphasizingits participation in a broad network of signalingaxes whichcould affectvariouscancers and investigating its promising therapeutic possibility.

Roles of non-coding RNAs in cell death pathways involved in the treatment of resistance and recurrence of cancer

Considering the burden of cancer, a number of methods have been applied to control or stop it. However, because of drug resistance or cancer recurrence, these treatments usually face failure. Combination of modulation of expression of non-coding RNAs (ncRNAs) with other treatments can increase treatment-sensitivity of tumors but these approaches still face some challenges. Gathering information in this field is a prerequisite to find more efficient cures for cancer. Cancer cells use ncRNAs to enhance uncontrolled proliferation originated from inactivation of cell death routs. In this review article, the main routes of cell death and involved ncRNAs in these routes are discussed. Moreover, extant information in the role of different ncRNAs on cell death pathways involved in the treatment resistance and cancer recurrence is summarized.

A Novel Derivative of Curcumol, HCL-23, Inhibits the Malignant Phenotype of Triple-Negative Breast Cancer and Induces Apoptosis and HO-1-Dependent Ferroptosis

Triple-negative breast cancer (TNBC) is the most aggressive molecular subtype of breast cancer. Curcumol, as a natural small molecule compound, has potential anti-breast cancer activity. In this study, we chemically synthesized a derivative of curcumol, named HCL-23, by structural modification and explored its effect on and underlying mechanism regarding TNBC progression. MTT and colony formation assays demonstrated that HCL-23 significantly inhibited TNBC cells proliferation. HCL-23 induced G2/M phase cell cycle arrest and repressed the capability of migration, invasion, and adhesion in MDA-MB-231 cells. RNA-seq results identified 990 differentially expressed genes including 366 upregulated and 624 downregulated genes. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) revealed that these differentially expressed genes were obviously enriched in adhesion, cell migration, apoptosis, and ferroptosis. Furthermore, HCL-23 induced apoptosis via the loss of mitochondrial membrane potential and the activation of the caspase family in TNBC cells. In addition, HCL-23 was verified to trigger ferroptosis through increasing cellular reactive oxygen species (ROS), labile iron pool (LIP), and lipid peroxidation levels. Mechanistically, HCL-23 markedly upregulated the expression of heme oxygenase 1 (HO-1), and the knockdown of HO-1 could attenuate ferroptosis induced by HCL-23. In animal experiments, we found that HCL-23 inhibited tumor growth and weight. Consistently, the upregulation of Cleaved Caspase-3, Cleaved PARP, and HO-1 expression was also observed in tumor tissues treated with HCL-23. In summary, the above results suggest that HCL-23 can promote cell death through activating caspases-mediated apoptosis and HO-1-dependent ferroptosis in TNBC. Therefore, our findings provide a new potential agent against TNBC.

LOC554202 contributes to chordoma progression by sponging miR-377-3p and up-regulating SMAD3

Chordoma is a rare malignant bone tumor originating from the remnants of the notochord. Here, the role of long noncoding LOC554202 in chordoma progression and its associated mechanism were explored. Cell proliferation was analyzed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide and colony formation assays. Flow cytometry was conducted to analyze cell apoptosis rate. The migration and invasion of chordoma cells were analyzed by transwell migration and invasion assays and wound healing assays. A xenograft tumor model was established in nude mice to explore the role of LOC554202 in regulating tumor growth in vivo . The interaction between microRNA-377-3p (miR-377-3p) and LOC554202 or sekelsky mothers against d PP (SMAD) family member 3 (SMAD3) was verified by dual-luciferase reporter and RNA immunoprecipitation assays. The glycolytic rate of chordoma cells was analyzed using glucose assay kit, lactic acid kit and ApoSENSOR ADP/ATP ratio assay kit. LOC554202 expression was upregulated in chordoma tissues and cell lines. LOC554202 silencing suppressed the proliferation, migration and invasion and induced the apoptosis of chordoma cells. LOC554202 knockdown restrained xenograft tumor growth in vivo . miR-377-3p was confirmed as a target of LOC554202, and miR-377-3p silencing largely overturned LOC554202 knockdown-mediated anti-tumor effects in chordoma cells. miR-377-3p interacted with the 3' untranslated region (3'UTR) of SMAD3 and miR-377-3p overexpression-mediated antitumor effects in chordoma cells were largely attenuated by SMAD3 overexpression. LOC554202 could positively regulate SMAD3 expression by sponging miR-377-3p in chordoma cells. LOC554202 contributed to the glycolysis of chordoma cells by targeting binding to miR-377-3p/SMAD3 axis. LOC554202 facilitated the proliferation, migration, invasion and glycolysis and inhibited the apoptosis of chordoma cells by mediating miR-377-3p/SMAD3 axis.

MIR31HG Expression Predicts Poor Prognosis and Promotes Colorectal Cancer Progression

Purpose

Long noncoding RNAs (lncRNAs) are correlated with cancer pathogenesis and prognosis. Many studies have shown that aberrant expression of MIR31HG is implicated in the cancer progression and patient prognosis. However, the biological function and predictive value of MIR31HG in colorectal cancer is unclear.

Methods

The correlation between MIR31HG expression and clinicopathological characteristics of colorectal cancer patients was analyzed by collating the information from The Cancer Genome Atlas (TCGA) database. Kaplan–Meier analysis, univariable and multivariable Cox regression analysis were performed to evaluate the prognostic value of MIR31HG. Gene set enrichment analysis (GSEA) was conducted to identify the potential carcinogenic mechanisms implicated in MIR31HG. Moreover, MIR31HG was knocked down using siRNA in colorectal cancer cells, and cell migration, invasion, growth and colony formation assays were performed. The expression of MIR31HG influenced gene markers was quantified by qRT-PCR in MIR31HG-silenced colorectal cancer cells.

Results

In TCGA database, we found that MIR31HG was elevated in colorectal cancer patients. The patients with high MIR31HG expression had poor overall survival and disease-specific survival. Univariable and multivariable analyses showed that MIR31HG expression was an independent prognostic predictor in colorectal cancer patients. GSEA revealed that MIR31HG mainly modulated focal adhesion, extracellular matrix organization, integrin cell surface interactions and focal adhesion-PI3K-Akt-mTOR-signaling pathway. Besides, MIR31HG knockdown significantly impaired colorectal cancer cell migration, invasion, growth and colony formation. Further qRT-PCR data confirmed that alteration of MIR31HG expression notably affected the tumorigenesis-related key gene expression in the cells.

Conclusion

Our findings provide evidence that MIR31HG is a key factor in maintaining the malignant phenotype of colorectal cancer and may act as an independent predictor for patients with colorectal cancer.

Long non-coding RNA MIR31HG as a prognostic predictor for malignant cancers: A meta- and bioinformatics analysis

Background

The possible regulatory mechanism of MIR31HG in human cancers remains unclear, and reported results of the prognostic significance of MIR31HG expression are inconsistent.

Methods

The meta‐analysis and related bioinformatics analysis were conducted to evaluate the role of MIR31HG in tumor progression.

Results

The result showed that high MIR31HG expression was not related to prognosis. However, in the stratified analysis, we found that the overexpression of MIR31HG resulted in worse OS, advanced TNM stage, and tumor differentiation in respiratory system cancers. Moreover, our results also found that MIR31HG overexpression was related to shorter OS in cervical cancer patients and head and neck tumors. In contrast, the MIR31HG was lower in digestive system tumors which contributed to shorter overall survival, advanced TNM stage, and distant metastasis. Furthermore, the bioinformatics analysis showed that MIR31HG was highly expressed in normal urinary bladder, small intestine, esophagus, stomach, and duodenum and low in colon, lung, and ovary. The results obtained from FireBrowse indicated that MIR31HG was highly expressed in LUSC, CESC, HNSC, and LUAD and low in STAD and BLCA. Gene Ontology analysis showed that the co‐expressed genes of MIR31HG were most enriched in the biological processes of peptide metabolism and KEGG pathways were most enriched in Ras, Rap1, and PI3K‐Akt signaling pathway.

Conclusion

MIR31HG may serve as a potential biomarker in human cancers.

LINC00174 Facilitates Proliferation and Migration of Colorectal Cancer Cells via MiR-3127-5p/ E2F7 Axis

The literature indicates that LINC00174 promotes the growth of colorectal cancer (CRC) cells, but its research needs to be enriched. We tried to explore the function and mechanism of LINC00174 in CRC cell proliferation and migration. Bioinformatics analysis predicted the binding relationship and expressions of lncRNA, miRNA and mRNA. Clinical study analyzes the relationship between LINC00174 and clinical data characteristics of CRC patients. The expressions of LINC00174, miR-3127-5p and E2F7 were verified by RT-qPCR, and the combination of the two was verified by dual luciferase analysis and RNA immunoprecipitation as needed. Western blot was used to detect the expression of EMT-related protein and E2F7 protein. Functional experiments were used to evaluate the function of the target gene on CRC cells. LINC00174 was up-regulated in CRC clinical samples and cells and was related to the clinical characteristics of CRC patients. High-expression of LINC00174, contrary to the effect of siLINC00174, promoted cell viability, proliferation, migration and invasion, up-regulated the expressions of N-Cadherin, Vimentin, E2F7, and inhibited the expression of E-Cadherin. MiR-3127-5p was one of the targeted miRNAs of LINC00174 and was down-regulated in CRC samples. In addition, miR-3127-5p mimic partially reversed the malignant phenotype of CRC cells induced by LINC00174. Besides, E2F7 was a target gene of miR-3127-5p, and LINC00174 repressed miR-3127-5p to regulate E2F7. Our research reveals that LINC00174 affected the biological characteristics of CRC cells through regulated miR-3127-5p/ E2F7 axis.

LncRNA BLACAT1/miR-519d-3p/CREB1 Axis Mediates Proliferation, Apoptosis, Migration, Invasion, and Drug-Resistance in Colorectal Cancer Progression

BACKGROUND

Colorectal cancer (CRC) is a common severe disease around the world. The merging papers reported that long noncoding RNAs (lncRNAs) took part in the diversified pathological processes of CRC. This study aimed to uncover the role and the potential mechanism of lncRNA bladder cancer-associated transcript 1 (BLACAT1) in CRC progression.

METHODS

LncRNA BLACAT1, micro-519d-3p (miR-519d-3p), and cAMP-responsive element binding protein 1 (CREB1) levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in CRC tissues and cells. The bio-functional effects were examined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry assay, and transwell assay. The susceptibility testing was determined by oxaliplatin (OXA) administration. The potential binding sites between miR-519d-3p and BLACAT1 or CREB1 were predicted by online software starBase and confirmed by dual-luciferase reporter analysis. The relative proteins expression in CRC cells was determined by Western blot analysis. Xenograft tumor model was used to evaluate biological function of BLACAT1 in vivo.

RESULTS

The expression of BLACAT1 was promoted in CRC tissues and cells, and correlated to the TNM (tumor, node, metastasis) stage, distant metastasis, and overall survival rate. Silencing of BLACAT1 limited the proliferation, migration, and invasion, facilitated the apoptosis, and re-sensitized OXA-resistance in CRC cells. MiR-519d-3p was a target of BLACAT1. Furthermore, miR-519d-3p deletion reversed the positive effects of BLACAT1 deletion on CRC cells. Moreover, our data showed that miR-519d-3p directly targeted CREB1 and BLACAT1 sponged miR-519d-3p to regulate CREB1 expression. Besides, CREB1 disrupted the bio-functional results above from BLACAT1 suppression. Additionally, BLACAT1 knockdown promoted CRC cells sensitivity to OXA in vivo.

CONCLUSION

BLACAT1 mediated the progression of CRC and OXA-resistance by miR-519d-3p/CREB1 axis.

Long noncoding RNA MIR31HG and its splice variants regulate proliferation and migration: prognostic implications for muscle invasive bladder cancer

Background

Growing evidence supports the pivotal role of long non-coding RNAs (lncRNAs) in the regulation of cancer development and progression. Their expression patterns and biological function in muscle invasive bladder cancer (MIBC) remain elusive.

Methods

Transcript levels of lncRNA miR-31 host gene (MIR31HG) and its splice variants were measured in our MIBC cohort (n = 102) by qRT-PCR, and validated in silico by the TCGA cohort (n = 370). Kaplan-Meier and multiple Cox regression analysis were conducted to evaluate the survival significance of MIR31HG and its splice variants. Functional experiments were performed to examine the proliferation and migration abilities of MIR31HG and its splice variants by knockdown approaches.

Results

In this study, a decreased expression of MIR31HG was found in bladder cancer cells and tissues, except in the basal subtype. Survival analysis showed that high expression of MIR31HG was associated with poor overall survival (OS) and disease-free survival (DFS) in patients with MIBC of basal subtype. Two splice variants of MIR31HG lacking exon 1 (MIR31HGΔE1) and exon 3 (MIR31HGΔE3) were identified to have specific expression patterns in different molecular subtypes of our MIBC cohort. MIR31HGΔE3 was highly expressed in basal subtype tumors. A high expression of MIR31HGΔE1 and MIR31HGΔE3 was associated with worse OS and DFS in our cohort. In vitro experiments revealed that knockdown of MIR31HG inhibits cell proliferation, colony formation, and migration in bladder cancer. Cell proliferation and migration assays after knockdown of splice variants of MIR31HG showed corresponding roles for the full-length transcript.

Conclusions

Our study demonstrates that MIR31HG and its splice variants could serve as biomarkers for the classification and prognosis prediction of patients with MIBC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-020-01795-5.

Role of non-coding RNAs as novel biomarkers for detection of colorectal cancer progression through interaction with the cell signaling pathways

Colorectal cancer (CRC) is one of the most common types of cancer which affects the colon and the rectum. Approximately one third of annual CRC mortality occurs due to the late detection of this type of cancer. Therefore, there is an urgent need for more powerful diagnostic and prognostic tools for identification and treatment of colorectal tumorigenesis. Non-coding RNAs (ncRNAs) have been implicated in the pathology of CRC and also linked to metastasis, proliferation, differentiation, migration, angiogenesis and apoptosis in numerous cancers. Recently, attention has turned towards ncRNAs as specific targets for diagnosis, prognosis and treatment of various types of cancers, including CRC. In this review, we have tried to outline the roles of ncRNAs, and their involvement in signaling pathways responsible for the progression of CRC.

The predictive value of lncRNA MIR31HG expression on clinical outcomes in patients with solid malignant tumors

Background

Emerging studies have explored the prognostic value of MIR31HG in cancers, but its role remains elusive. Herein, we aimed to summarize the prognostic potential of MIR31HG in this study.

Methods

Several databases were searched for literature retrieval on Dec 5, 2019. Overall and subgroup analyses were conducted to measure the relationship between MIR31HG expression and clinical outcomes. Moreover, GEPIA was applied for validation of prognostic value of MIR31HG in tumor patients in TCGA dataset.

Results

Overall, seventeen studies with 2573 patients were enrolled. Compared to counterparts, those patients with high MIR31HG expression tended to have shorter RFS. Notably, MIR31HG overexpression predicted unfavorable OS in lung cancer. By contrast, gastrointestinal cancer patients with elevated MIR31HG expression predicted better OS and disease-free survival. Additionally, MIR31HG overexpression was significantly associated with worse clinicopathological features including advanced tumor stage and LNM in lung cancer, but favorable clinical characteristics in gastrointestinal cancer. Moreover, the positive association between MIR31HG and OS in lung cancer was further confirmed in TCGA dataset.

Conclusion

Overexpression of MIR31HG suggested remarkable association with poor prognosis in terms of OS, tumor stage, and LNM in lung cancer, but favorable prognosis in gastrointestinal cancer. Therefore, MIR31HG may serve as a promising prognostic biomarker in multiple cancers.

Significance of lncRNA MIR31HG in predicting the prognosis for Chinese patients with cancer: a meta-analysis

It is important to clarify the significance of long noncoding RNA MIR31 host gene (lncRNA MIR31HG) in predicting the prognosis for malignant tumors through meta-analysis. Electronic databases were systemically searched, from inception until 2 January 2019, to identify related articles. Meanwhile, the hazard ratios (odds ratios) and 95% CIs were computed for exploring the association between the expression of lncRNA MIR31HG and the survival (pathological variables). Eleven studies with 1041 cases were enrolled into the current meta-analysis. Low expression of lncRNA MIR31HG showed correlation with the dismal overall survival, disease-free survival, high tumor stage and lymph node metastasis among patients with digestive system cancers. Low expression of lncRNA MIR31HG may serve as a potential novel factor to indicate the dismal prognosis and metastasis in patients with digestive system cancers.

Long non-coding RNA LOC554202 promotes acquired gefitinib resistance in non-small cell lung cancer through upregulating miR-31 expression

Non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation inevitably have a relapse due to the occurrence of acquired resistance, resulting in treatment failure. However, little is known about the mechanisms of acquired resistance of NSCLC patients. Here, we elucidated the expression pattern of LOC554202 and miR-31, and their biological functions and mechanisms in NSCLC with acquired EGFR TKI resistance to gefitinib. In the present study, we observed that LOC554202 and miR-31 promoted proliferation and clonogenic growth of gefitinib-resistant NSCLC cells in vitro. LOC554202 upregulated miR-31 expression and they both reduced sensitivity of NSCLC cells to gefitinib. In a xenograft mice model, we found that knockdown of miR-31 significantly repressed gefitinib-resistant NSCLC cells growth in vivo. Furthermore, both LOC554202 and miR-31 levels were significantly increased in NSCLC patients acquiring resistance to gefitinib, and the expression of LOC554202 was positively correlated with the expression of miR-31. By luciferase reporter assays, we identified RAS P21 Protein Activator 1 (RASA1) and Hypoxia Inducible Factor 1 Subunit Alpha Inhibitor (FIH-1) as direct targets of miR-31 in NSCLC cells. Mechanistically, miR-31 directly repressed RASA1 and FIH-1 expression, and thus, at least partially activated the RAF-MEK-ERK and PI3K-AKT signaling pathways in NSCLC with acquired resistance to gefitinib. In conclusion, these data will help us develop potential therapeutic targets for the diagnosis and treatment of acquired EGFR TKI resistance in EGFR-mutant NSCLC.

LncRNAs as Regulators of Autophagy and Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is a common malignancy with 1. 8 million cases in 2018. Autophagy helps to maintain an adequate cancer microenvironment in order to provide nutritional supplement under adverse conditions such as starvation and hypoxia. Additionally, most of the cases of CRC are unresponsive to chemotherapy, representing a significant challenge for cancer therapy. Recently, autophagy induced by therapy has been shown as a unique mechanism of resistance to anticancer drugs. In this regard, long non-coding RNAs (lncRNAs) analysis are important for cancer detection, progression, diagnosis, therapy response, and prognostic values. With increasing development of quantitative detection techniques, lncRNAs derived from patients' non-invasive samples (i.e., blood, stools, and urine) has become into a novel approach in precision oncology. Tumorspecific GAS5, HOTAIR, H19, and MALAT are novels CRC related lncRNAs detected in patients. Nonetheless, the effect and mechanism of lncRNAs in cancer autophagy and chemoresistance have not been extensively characterized. Chemoresistance and autophagy are relevant for cancer treatment and lncRNAs play a pivotal role in resistance acquisition for several drugs. LncRNAs such as HAGLROS, KCNQ1OT1, and H19 are examples of lncRNAs related to chemoresistance leaded by autophagy. Finally, clinical implications of lncRNAs in CRC are relevant, since they have been associated with tumor differentiation, tumor size, histological grade, histological types, Dukes staging, degree of differentiation, lymph node metastasis, distant metastasis, recurrent free survival, and overall survival (OS).

Diagnostic and prognostic potential of tissue and circulating long non-coding RNAs in colorectal tumors

Long non-coding RNAs (lncRNAs) are members of the non-protein coding RNA family longer than 200 nucleotides. They participate in the regulation of gene and protein expression influencing apoptosis, cell proliferation and immune responses, thereby playing a critical role in the development and progression of various cancers, including colorectal cancer (CRC). As CRC is one of the most frequently diagnosed malignancies worldwide with high mortality, its screening and early detection are crucial, so the identification of disease-specific biomarkers is necessary. LncRNAs are promising candidates as they are involved in carcinogenesis, and certain lncRNAs (e.g., CCAT1, CRNDE, CRCAL1-4) show altered expression in adenomas, making them potential early diagnostic markers. In addition to being useful as tissue-specific markers, analysis of circulating lncRNAs (e.g., CCAT1, CCAT2, BLACAT1, CRNDE, NEAT1, UCA1) in peripheral blood offers the possibility to establish minimally invasive, liquid biopsy-based diagnostic tests. This review article aims to describe the origin, structure, and functions of lncRNAs and to discuss their contribution to CRC development. Moreover, our purpose is to summarise lncRNAs showing altered expression levels during tumor formation in both colon tissue and plasma/serum samples and to demonstrate their clinical implications as diagnostic or prognostic biomarkers for CRC.

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.

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

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

Long noncoding RNA MIR31HG is activated by SP1 and promotes cell migration and invasion by sponging miR-214 in NSCLC

Long non-coding RNAs(lncRNAs) have been reported to play pivotal roles in various cancers. Recently, MIR31HG was proposed to be involved in tumor progression. However, its role in non small cell lung cancer(NSCLC) remains elusive. In this work, we found that SP1-induced MIR31HG was significantly upregulated in NSCLC tissues and cell lines. Moreover, Cox multivariate survival analysis revealed that high MIR31HG was an independent predictor of poor overall survival(OS). Functionally, knockdown of TINCR obviously suppressed NSCLC cells migration and invasion in vitro and inhibited NSCLC cells metastasis in vivo. Mechanistically, we identified MIR31HG could act as a miR-214 sponge using RNA pull down, luciferase reporter and RIP assays. Lastly, we verified that overexpression of MIR31HG effectively reverses miR-214-induced inhibition of NSCLC cells progression. Therefore, MIR31HG might serve as a promising prognostic marker and potential therapeutic target for NSCLC patients.

Regulation Mechanism of Long Noncoding RNAs in Colon Cancer Development and Progression

Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide, and its high rates of relapse and metastasis are associated with a poor prognosis. Despite extensive research, the underlying regulatory mechanisms of CRC remain unclear. Long noncoding RNAs (lncRNAs) are a major type of noncoding RNAs that have received increasing attention in the past few years, and studies have shown that they play a role in many biological processes in CRC. Here, we summarize recent studies on lncRNAs associated with CRC and the signaling pathways and mechanisms underlying this association. We show that dysregulated lncRNAs may be new prognostic and diagnostic biomarkers or therapeutic targets for clinical application. This review contributes not only to our understanding of CRC, but also suggests novel signaling pathways associated with lncRNAs that can be targeted to block or eradicate CRC.

The long noncoding RNA TPTE2P1 promotes the viability of colorectal cancer cells

Long noncoding RNAs (lncRNAs) have important functions in tumor development and progression, including colorectal cancer (CRC), but their roles are not completely understood. In this study, the roles of the lncRNA transmembrane phosphoinositide 3-phosphatase and tensin homolog 2 pseudogene 1 (TPTE2P1), previously implicated in gallbladder cancer cell migration and invasion, were evaluated in CRC. In particular, quantitative polymerase chain reaction was used to quantify TPTE2P1 levels in tumor tissues and cell lines. The association between TPTE2P1 and survival was analyzed using the online tool OncoLnc. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, colony formation assays, and flow cytometry were used to evaluate the effects of TPTE2P1 on viability, cell cycle progression, and apoptosis. Signaling pathway proteins were quantitated by Western blot analysis. Finally, the role of TPTE2P1 was analyzed in vivo using mouse models. TPTE2P1 levels were significantly higher in CRC tissues than in adjacent normal tissues. Higher expression was associated with a poor survival rate. The silencing of TPTE2P1 led to cell cycle arrest at the S phase and thereby inhibited cell viability. TPTE2P1 knockdown also caused cancer cell apoptosis via the activation of the apoptosis regulator (BCL2)/caspase 3 signaling cascade. In addition, the inhibition of TPTE2P1 had suppressive effects on tumors in vivo. TPTE2P1 is upregulated in CRC and plays essential roles in the regulation of cell viability in vitro and tumor formation in vivo.

Alteration of the tumor suppressor SARDH in sporadic colorectal cancer: A functional and transcriptome profiling-based study

Sporadic colorectal cancer (sCRC) is one of the leading causes of cancer death worldwide. As a highly heterogeneous complex disease, the currently reported classical genetic markers for sCRC, including APC, KRAS, BRAF, and TP53 gene mutations and epigenetic alterations, can explain only some sCRC patients. Here, we first reported a deleterious c.551C>T mutation in SARDH in sCRC. SARDH was identified as a novel tumor suppressor gene and was abnormally decreased in sCRC at both the transcriptional and the translational level. SARDH mRNA levels were also down-regulated in oesophageal cancer, lung cancer, liver cancer, and pancreatic cancer in the TCGA database. SARDH overexpression inhibited the proliferation, migration, and invasion of CRC cell lines, whereas its depletion improved these processes. SARDH overexpression was down-regulated in multiple pathways, especially in the chemokine pathway. The SARDH transcript level was positively correlated with the methylation states of CXCL1 and CCL20. Therefore, we concluded that SARDH depletion is involved in the development of sCRC.

Knockdown of lncRNA MIR31HG inhibits cell proliferation in human HaCaT keratinocytes

BACKGROUND

Psoriasis is a complex, chronic inflammatory skin disease with substantial negative effects on patient quality of life. Long non-coding RNAs (lncRNAs) are able to be involved in multitudes of cellular processes in diverse human diseases. This study aimed to investigate the potential involvement of lncRNA MIR31HG in HaCaT keratinocytes proliferation.

RESULTS

The study showed that MIR31HG was significantly elevated in the lesional psoriatic skin compared with normal individuals' skin. Knockdown of MIR31HG inhibited HaCaT keratinocytes proliferation. Flow cytometry analysis showed that siRNA-mediated MIR31HG depletion induced cell cycle arrest in the G2/M phase. In addition, MIR31HG expression was found to be dependent on NF-κB activation.

CONCLUSIONS

NF-κB activation mediated MIR31HG upregulation plays an important role in the regulation of HaCaT keratinocytes proliferation. It could be a potential diagnostic biomarker and therapeutic target for psoriasis.

Long noncoding RNA MIR31HG inhibits hepatocellular carcinoma proliferation and metastasis by sponging microRNA-575 to modulate ST7L expression

Background

Emerging evidences have indicated that long noncoding RNAs (lncRNAs) play essential roles in the development and progression of cancers. Dysregulation of lncRNA MIR31HG has recently been reported in several types of cancers, and researches on the function of MIR31HG in cancers suggested that MIR31HG could act as either oncogene or tumor suppressor. But the functional involvement of MIR31HG has not been studied in hepatocellular carcinoma (HCC).

Methods

In this study, MTS assays, colony formation assay, Wound-healing assay, Transwell assy, and tumor xenografts experiments were used to identify biological effects of MIR31HG on HCC cells HCC proliferation and metastasis in vitro and in vivo. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to show the interactions of MIR31HG and miR-575. The bioinformatics methods were completed to find the target genes of miR-575. And Dual-luciferase reporter assay and Western blot analysis were further used to confirm the target gene of miR-575.

Results

We found that overexpression of MIR31HG obviously suppressed HCC proliferation and metastasis in vitro and in vivo, whereas knockdown of MIR31HG had the opposite effects. Besides, overexpression of MIR31HG significantly decreased the expression of microRNA-575 (miR-575), which plays an oncogenic role in HCC. Moreover, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay revealed that MIR31HG exerted tumor-suppressive functions by binding directly to miR-575, and there was a reciprocal inhibition between MIR31HG and miR-575 in the same RNA-induced silencing complex (RISC). Furthermore, overexpression of MIR31HG enhanced the expression of suppression of tumorigenicity 7 like (ST7L), which was identified as a downstream target gene of miR-575. Thus, MIR31HG positively regulated ST7L expression through sponging miR-575, and acted as tumor suppressor in HCC.

Conclusions

Overall, our study illuminates the role of MIR31HG as a miRNA sponge in HCC, and sheds new light on lncRNA-directed diagnostics and therapeutics in HCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0853-9) contains supplementary material, which is available to authorized users.

LncRNA MIR31HG overexpression serves as poor prognostic biomarker and promotes cells proliferation in lung adenocarcinoma

MIR31HG, as the host gene of miR-31, has been suggested to involve in various cancer developments. However, little is known about the clinical significance and biological function of MIR31HG in lung adenocarcinoma. In our study, we found MIR31HG was highly expressed in lung adenocarcinoma tissues and cell lines, and associated with clinical staging, N classification, M classification and differentiated degree. Survival analysis showed MIR31HG high-expression was an independent unfavorable prognostic factor for lung adenocarcinoma patients. Loss-of-function studies suggested down-regulation of MIR31HG inhibited lung adenocarcinoma cells proliferation and blocked cell-cycle, but has no effect on cell apoptosis. There was no correlation between MIR31HG and miR-31 expression in lung adenocarcinoma tissues, down-regulation of MIR31HG had no effect on the expression of miR-31 in lung adenocarcinoma cells. In conclusion, MIR31HG high-expression is an independent unfavorable prognostic factor for lung adenocarcinoma patients, and serves an oncogenic role to modulate lung adenocarcinoma cells proliferation and cell-cycle.

Roles of long noncoding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is the 3^rd most common malignancies worldwide. Metastasis is responsible for more than 90% CRC patients' death. Long noncoding RNAs (lncRNAs) are an important class of transcribed RNA molecules greater than 200 nucleotides in length. With the development of whole genome sequencing technologies, they have been gained more attention. Accumulating evidences suggest that abnormal expression of lncRNAs in diverse diseases are involved in various biological functions such as proliferation, apoptosis, metastasis and differentiation by acting as epigenetic, splicing, transcriptional or post-transcriptional regulators. Aberrant expression of lncRNAs has also been found in CRC. Besides, recent studies have indicated that lncRNAs play important roles in tumourigenesis and cancer metastasis. They participate in the process of metastasis by activing or inhibiting the metastatic pathways. However, their functions on the development of cancer metastasis are poorly understood. In this review, we highlight the findings of roles for lncRNAs in CRC metastasis and review the metastatic pathways of lncRNAs leading to cancer metastasis in CRC, including escape of apoptosis, epithelial-mesenchymal transition (EMT), angiogenesis and invasion, migration and proliferation. Furthermore, we also discuss the potential clinical application of lncRNAs in CRC as diagnostic markers and therapeutic targets.

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

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

Long noncoding RNA RP4 functions as a competing endogenous RNA through miR-7-5p sponge activity in colorectal cancer

AIM

To investigate the role of long noncoding RNA (lncRNA) RP4 in colorectal cancer.

METHODS

Lentivirus-mediated lncRNA RP4 overexpression and knockdown were performed in the colorectal cancer cell line SW480. Cell proliferation, tumor growth, and early apoptosis were evaluated by a cell counting kit-8 assay, an in vivo xenograft tumor model, and annexin V/propidium iodide staining, respectively. Analysis of the lncRNA RP4 mechanism involved assessment of the association of its expression with miR-7-5p and the SH3GLB1 gene. Western blot analysis was also performed to assess the effect of lncRNA RP4 on the autophagy-mediated cell death pathway and phosphatidylinositol-3-kinase (PI3K)/Akt signaling.

RESULTS

Cell proliferation, tumor growth, and early apoptosis in SW480 cells were negatively regulated by lncRNA RP4. Functional experiments indicated that lncRNA RP4 directly upregulated SH3GLB1 expression by acting as a competing endogenous RNA (ceRNA) for miR-7-5p. This interaction led to activation of the autophagy-mediated cell death pathway and de-repression of PI3K and Akt phosphorylation in colorectal cancer cells in vivo.

CONCLUSION

Our results demonstrated that lncRNA RP4 is a ceRNA that plays an important role in the pathogenesis of colorectal cancer, and could be a potential therapeutic target for colorectal cancer treatment.

LncRNA CCND2-AS1 is up-regulated and regulates proliferation, migration, and invasion in breast cancer

Many long non-coding RNAs (lncRNAs) have been found to exert influences on biological processes including tumorigenesis. Many lncRNAs have been reported as potential therapeutic targets and prognostic biomarkers in multiple cancers. CCND2 antisense RNA 1 (CCND2-AS1) is an lncRNA recently reported to be involved in the progression of glioma cancers. However, whether CCND2-AS1 is associated with progression of breast cancer remains unknown. In this study, quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure CCND2-AS1 gene expression in breast cancer cell in lines. CCND2-AS1 expression was significantly over-expressed compared to normal breast epithelial cells. Gain-and loss-of-function experiments were performed in vitro to investigate the role of CCND2-AS1, where we found that CCND2-AS1 knockdown in MDA-MB-231 significantly suppressed cell proliferation, migration, and invasion. In contrast, CCND2-AS1 overexpression in BT-549 had the opposite effects. Our findings indicate that lncRNA CCND2-AS1 is a gene associated with breast cancer and might become a potential therapeutic target.

Clinical significance of long non-coding RNA ZEB2-AS1 in locally advanced colorectal cancer

OBJECTIVE

The aim of this study was to investigate the clinical significance of differential expression of long non-coding RNA (lncRNA) ZEB2-AS1 in patients with colorectal cancer (CRC).

METHODS

mRNA expression of lncRNA ZEB2-AS1 was evaluated by real-time quantitative PCR on eighty-seven cancerous tissues and adjacent normal mucosal tissues from patients with CRC tissue. Correlation between the lncRNA ZEB2-AS1 expression and clinicopathological characteristics of the colorectal cancer patients was evaluated, and five-year overall survival (OS) was also analyzed according to the lncRNA ZEB2-AS1 expression of the CRC patients. Moreover, Cox Regression Analysis was performed in screening prognosis factors.

RESULTS

A significantly upregulated lncRNA ZEB2-AS1 expression, with a fold change of 18.75, was found in CRC tissue compared to the normal tissue. lncRNA ZEB2-AS1 expression in CRC was correlated with death (P<0.001). The five-year OS was 43.2% and 76.7%, respectively, in patients with higher and lower lncRNA ZEB2-AS1 expression. Cox regression analysis showed that location (P=0.020), N1 staging (P=0.021) and lncRNA ZEB2-AS1 lower expression (P<0.001) were independent prognosis factors associated with a better OS.

CONCLUSION

Expression of lncRNA ZEB2-AS1 was significantly upregulated in stage III CRC patients and affects the prognosis.

The regulatory network analysis of long noncoding RNAs in human colorectal cancer

Colorectal cancer (CRC) is among one of the most prevalent and lethiferous diseases worldwide. Long noncoding RNAs (lncRNAs) are commonly accepted to function as a key regulatory factor in human cancer, but the potential regulatory mechanisms of CRC-associated lncRNA are largely obscure. Here, we integrated several expression profiles to obtain 55 differentially expressed (DE) lncRNAs. We first detected lncRNA interactions with transcription factors, microRNAs, mRNAs, and RNA-binding proteins to construct a regulatory network and then create functional enrichment analyses for them using bioinformatics approaches. We found the upregulated genes in the regulatory network are enriched in cell cycle and DNA damage response, while the downregulated genes are enriched in cell differentiation, cellular response, and cell signaling. We then employed module-based methods to mine several intriguing modules from the overall network, which helps to classify the functions of genes more specifically. Next, we confirmed the validity of our network by comparisons with a randomized network using computational method. Finally, we attempted to annotate lncRNA functions based on the regulatory network, which indicated its potential application. Our study of the lncRNA regulatory network provided significant clues to unveil lncRNAs potential regulatory mechanisms in CRC and laid a foundation for further experimental investigation.

Natural Antisense Transcripts: Molecular Mechanisms and Implications in Breast Cancers

Natural antisense transcripts are RNA sequences that can be transcribed from both DNA strands at the same locus but in the opposite direction from the gene transcript. Because strand-specific high-throughput sequencing of the antisense transcriptome has only been available for less than a decade, many natural antisense transcripts were first described as long non-coding RNAs. Although the precise biological roles of natural antisense transcripts are not known yet, an increasing number of studies report their implication in gene expression regulation. Their expression levels are altered in many physiological and pathological conditions, including breast cancers. Among the potential clinical utilities of the natural antisense transcripts, the non-coding|coding transcript pairs are of high interest for treatment. Indeed, these pairs can be targeted by antisense oligonucleotides to specifically tune the expression of the coding-gene. Here, we describe the current knowledge about natural antisense transcripts, their varying molecular mechanisms as gene expression regulators, and their potential as prognostic or predictive biomarkers in breast cancers.

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.

Long non-coding RNA LOC554202 modulates chordoma cell proliferation and invasion by recruiting EZH2 and regulating miR-31 expression

OBJECTIVES

Chordoma is a rare malignant bone tumour arising from notochordal remnants. Long non-coding RNA LOC554202, as the host gene of miR-31, contributes to various cancer developments. However, little is known about the biological function of LOC554202 in chordoma. Here, the relationship between LncRNA LOC554202, miR-31 and EZH2 was elucidated in chordoma.

MATERIALS AND METHODS

The levels of LOC554402, miR-31, EZH2, RNF144B, and epithelial-mesenchymal transition (EMT) markers were measured in chordoma tissues and the chordoma cell lines via quantitative real-time PCR (qRT-PCR) or Western blot. FISH assay demonstrated the LOC554402 expression in chordoma tissues. The chordoma cell lines, U-CH1 and JHC7, were transfected with siRNA or miRNA mimics and analysed for cell proliferation ability, apoptosis, cell migration, and invasion. RNA pull down, RIP assay, and Luciferase Reporter Assay were used to analyze the interaction between LOC554202 and EZH2. Animal tumour xenografts were generated, and qRT-PCR was performed to investigate EZH2, miR-31, and RNB144B expression on tumour growth in vivo.

RESULTS

We found elevated expression of LOC554202 was associated with a decreased level of miR-31 in cancer tissues. Knockdown of LOC554202 or overexpression of miR-31 suppressed the proliferation, migration, and invasion of chordoma cells. Unexpectedly, EZH2 as a binding protein of LOC554202, and it was positively regulated by LOC554202, leading to the reduced expression of miR-31. Furthermore, the impaired function of miR-31 restored expression of the oncogene RNF144B and maintained the metastasis-promoting activity in vitro. The results in vivo confirmed the anti-tumour effects of knockdown of LOC554202, which inhibited EZH2/miR-31 to activate the oncogene RNF144B.

CONCLUSION

Our results suggest that LOC554202 may play an important role in the progression of chordoma by the direct upregulation of EZH2 and indirect promotion of RNF144B via miR-31.

Long non-coding RNA HNF1A-AS1 promotes proliferation and suppresses apoptosis of bladder cancer cells through upregulating Bcl-2

Emerging evidences have indicated that long non-coding RNAs (lncRNAs) are pivotal regulators of tumor development and progression. HNF1A-AS1 (HNF1A antisense RNA 1, C12 or f27) is a novel long non-coding RNA that acts as a potential biomarker and is involved in development and progression of several cancers. Nevertheless, we know nothing about the clinical significance and molecular mechanism of HNF1A-AS1 in bladder cancer. In this study, we found that HNF1A-AS1 is significantly up-regulated in bladder cancer. Further experiments had demonstrated that silencing HNF1A-AS1 in bladder cancer cells could inhibit the proliferation and induce apoptosis. Mechanistically, we found down-regulated of HNF1A-AS1 increased the expression of miR-30b-5p and subsequently inhibited the expression of Bcl-2, in a ceRNA-dependent way. Moreover, knockdown of miR-30b-5p reversed cell proliferation inhibition and cell apoptosis induced by silencing HNF1A-AS1. In conclusions, we demonstrated that HNF1A-AS1 plays an important regulatory role in bladder cancer and shed new light on lncRNA-directed diagnostic and therapeutics in bladder cancer.

Downregulated long non-coding RNA TCONS_00068220 upregulates apoptosis in gastric cancer cells

Long non-coding RNAs (lncRNAs) are emerging as a fundamental class of biological effect or molecules that perform pivotal functions in the regulation of the genome. With advances in bioinformatics and genomics, extensive identification and characterization of lncRNAs is now possible. They regulate cellular growth, differentiation and apoptosis. Dysregulation of lncRNAs has been associated with numerous types of human cancer. In the present study, the expression profile of differentially expressed genes (DEGs) and lncRNAs in gastric cancer (GC) samples and normal tissue samples was evaluated with bioinformatics. The biological functions of the predicted lncRNA TCONS_00068220 were focused on; the DEGs co-expressed with TCONS_00068220 were enriched in cancer-associated pathways. TCONS_00068220 was demonstrated to be upregulated in GC tissues and cell lines compared with normal controls. In addition, an increased rate of apoptosis was observed in NCI-N87 cells following transfection with small interfering RNA against TCONS_00068220. These data suggest that TCONS_00068220 may be associated with the pathogenesis of GC, and it may serve as a potential therapeutic target.

LncRNAs: the bridge linking RNA and colorectal cancer

Long noncoding RNAs (lncRNAs) are transcribed by genomic regions (exceeding 200 nucleotides in length) that do not encode proteins. While the exquisite regulation of lncRNA transcription can provide signals of malignant transformation, lncRNAs control pleiotropic cancer phenotypes through interactions with other cellular molecules including DNA, protein, and RNA. Recent studies have demonstrated that dysregulation of lncRNAs is influential in proliferation, angiogenesis, metastasis, invasion, apoptosis, stemness, and genome instability in colorectal cancer (CRC), with consequent clinical implications. In this review, we explicate the roles of different lncRNAs in CRC, and the potential implications for their clinical application.

Long noncoding RNA CRNDE promotes colorectal cancer cell proliferation via epigenetically silencing DUSP5/CDKN1A expression

Evidence indicates that long non-coding RNAs (lncRNAs) play a critical role in the regulation of tumor cellular processes, such as proliferation, apoptosis, and metastasis. LncRNA CRNDE (Colorectal Neoplasia Differentially Expressed) is located at human chromosome 16 and has been found overexpressed in a variety of cancers including colorectal cancer (CRC). In this paper, we report that lncRNA CRNDE expression was remarkably upregulated in CRC tissues and that lncRNA CRNDE overexpression was positively correlated with advanced pathological stages and larger tumor sizes. In addition, the knockdown of CRNDE significantly suppressed proliferation and caused apoptosis of CRC cells both in vitro and in vivo. Furthermore, RNA immunoprecipitation and chromatin immunoprecipitation assays demonstrated that lncRNA CRNDE could epigenetically suppress the expressions of dual-specificity phosphatase 5 (DUSP5) and CDKN1A by binding to EZH2 (the key components of Polycomb repressive complex 2 (PRC2)), thus promoting CRC development. In conclusion, our data suggest that the lncRNA CRNDE promotes the progression of CRC and is a potential therapeutic target for CRC intervention.

The long non-coding RNA NONHSAT062994 inhibits colorectal cancer by inactivating Akt signaling

The aberrant expression of long noncoding RNAs (lncRNAs) is implicated in cancer development and progression. However, the clinical significance and mechanism by which NONHSAT062994 regulates colorectal cancer (CRC) is unknown. We here reported that NONHSAT062994 was significantly downregulated in human CRC tissues and cell lines. Moreover, its expression was inversely correlated with tumor size and overall survival (OS) time in CRC patients. In CRC cells, the overexpression and knockdown of NONHSAT062994 inhibited and enhanced CRC cell growth, respectively, in vitro and in vivo. Mechanistically, NONHSAT062994 functioned as a tumor suppressor to inhibit CRC cell growth by inactivating Akt signaling. Notably, the NONHSAT062994 expression status was negatively correlated with the Akt downstream targets c-Myc and Cyclin D1 in clinical CRC samples. The current findings suggest that NONHSAT062994 plays a critical role in the development of CRC by regulating Akt signaling, and identified a candidate prognostic biomarker or potential therapeutic target for CRC patients.

A novel lncRNA, LL22NC03-N64E9.1, represses KLF2 transcription through binding with EZH2 in colorectal cancer

Long noncoding RNAs (lncRNA) have been implicated in variety human cancer but their mechanisms of function are mainly undocumented. In the present study, we investigated lncRNAs alteration that contributed to colorectal cancer (CRC) by utilizing TCGA RNA sequencing data and other publicly available lncRNAs expression profiling data. Here, We screened out the CRC-associated lncRNA LL22NC03-N64E9.1, a key regulator of CRC development and progression. We also revealed that knockdown of LL22NC03-N64E9.1 inhibited cell proliferation, colony formation, tumorigenicity and apoptosis promotion, both in vitro and in vivo. Mechanistically, LL22NC03-N64E9.1 repressed underlying target gene KLF2 transcription through binding to EZH2. Furthermore, rescue experiments revealed that LL22NC03-N64E9.1 oncogenic function may partially depend on repressing KLF2. Taken together, our results suggested that LL22NC03-N64E9.1 confered an oncogenic function in human CRC and may serve as a candidate prognostic biomarker and target for new therapies in this deadly disease.

Involvement of Non-coding RNAs in the Signaling Pathways of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common diagnosed cancers worldwide. The metastasis and development of resistance to anti-cancer treatment are major challenges in the treatment of CRC. Understanding mechanisms underpinning the pathogenesis is therefore critical in developing novel agents for CRC treatments. A large number of evidence has demonstrated that non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs have functional roles in both the physiological and pathological processes by regulating the expression of their target genes. These molecules are engaged in the pathobiology of neoplastic diseases and are targets for the diagnosis, prognosis and therapy of a variety of cancers, including CRC. In this regard, ncRNAs have emerged as one of the hallmarks of CRC pathogenesis and they also play key roles in metastasis, drug resistance and the stemness of CRC stem cell by regulating various signaling networks. Therefore, a better understanding the ncRNAs involved in the signaling pathways of CRC may lead to the development of novel strategy for diagnosis, prognosis and treatment of CRC. In this chapter, we summarize the latest findings on ncRNAs, with a focus on miRNAs and lncRNAs involving in signaling networks and in the regulation of pathogenic signaling pathways in CRC.

α-Asarone suppresses the proliferation and migration of ASMCs through targeting the lncRNA-PVT1/miR-203a/E2F3 signal pathway in RSV-infected rats

Asthma is a chronic inflammatory pulmonary disease and respiratory syncytial virus (RSV) infection is a common cause of lower respiratory tract illness in infants and young children. α-Asarone presents many pharmacological effects and has been demonstrated to be useful in treating asthma. However, the functional mechanism of α-asarone in RSV-infected asthma has not been investigated. Long non-coding RNAs (lncRNAs) have been reported to play critical roles in many biological processes. Although many lncRNAs have been characterized, few were reported in asthma, especially in RSV-induced asthma. Currently, a novel post-transcriptional regulation has been proposed in which lncRNAs function as competing endogenous RNAs (ceRNAs) to competitively sponge miRNAs, thereby regulating the target genes. In the present study, we established an RSV-infected Sprague-Dawley rat model and demonstrated that lncRNA-PVT1 is involved in the mechanism of α-asarone in treating RSV-induced asthma, and lncRNA-PVT1 regulates the expression of E2F3 by functioning as a ceRNA which competitively sponges miR-203a.

Long non-coding RNA ATB promotes malignancy of esophageal squamous cell carcinoma by regulating miR-200b/Kindlin-2 axis

Esophageal squamous cell carcinoma (ESCC) is one of the leading causes of cancer-related death, especially in China. In addition, the prognosis of late stage patients is extremely poor. However, the biological significance of the long non-coding RNA lnc-ATB and its potential role in ESCC remain to be documented. In this study, we investigated the role of lnc-ATB and the underlying mechanism promoting its oncogenic activity in ESCC. Expression of lnc-ATB was higher in ESCC tissues and cell lines than that in normal counterparts. Upregulated lnc-ATB served as an independent prognosis predictor of ESCC patients. Moreover, loss-of-function assays in ESCC cells showed that knockdown of lnc-ATB inhibited cell proliferation and migration both in vitro and in vivo. Mechanistic investigation indicated that lnc-ATB exerted oncogenic activities via regulating Kindlin-2, as the anti-migration role of lnc-ATB silence was attenuated by ectopic expression of Kindlin-2. Further analysis showed that lnc-ATB functions as a molecular sponge for miR-200b and Kindlin-2. Dysregulated miR-200b/Kindlin-2 signaling mediated the oncogenic activity of lnc-ATB in ESCC. Our results suggest that lnc-ATB predicts poor prognosis and may serve as a potential therapeutic target for ESCC patients.

Long noncoding RNA LncHIFCAR/MIR31HG is a HIF-1α co-activator driving oral cancer progression

Long noncoding RNAs (lncRNAs) have been implicated in hypoxia/HIF-1-associated cancer progression through largely unknown mechanisms. Here we identify MIR31HG as a hypoxia-inducible lncRNA and therefore we name it LncHIFCAR (long noncoding HIF-1α co-activating RNA); we describe its oncogenic role as a HIF-1α co-activator that regulates the HIF-1 transcriptional network, crucial for cancer development. Extensive analyses of clinical data indicate LncHIFCAR level is substantially upregulated in oral carcinoma, significantly associated with poor clinical outcomes and representing an independent prognostic predictor. Overexpression of LncHIFCAR induces pseudo-hypoxic gene signature, whereas knockdown of LncHIFCAR impairs the hypoxia-induced HIF-1α transactivation, sphere-forming ability, metabolic shift and metastatic potential in vitro and in vivo. Mechanistically, LncHIFCAR forms a complex with HIF-1α via direct binding and facilitates the recruitment of HIF-1α and p300 cofactor to the target promoters. Our results uncover an lncRNA-mediated mechanism for HIF-1 activation and establish the clinical values of LncHIFCAR in prognosis and potential therapeutic strategy for oral carcinoma.

Cancer cells adapt to the changing microenvironment by activating different pathways through multiple mechanisms. Here the authors identify long noncoding RNA MIR31HG as a HIF-1α co-activator required for the induction of the hypoxic response and show its oncogenic role in oral carcinogenesis.

Overexpression of long non-coding RNA zinc finger antisense 1 in acute myeloid leukemia cell lines influences cell growth and apoptosis

The association between long non-coding RNA zinc finger antisense 1 (ZFAS1) and acute myeloid leukemia (AML) has not yet been investigated. The present study aimed to assess the potential role of ZFAS1 in AML cell proliferation and apoptosis. The expression of ZFAS1 mRNA in various AML cell lines (HL-60, KG-1, ML-1 and SKNO-1) was measured by reverse transcription-quantitative polymerase chain reaction. The results showed that ZFAS1 expression was increased in all four human AML cell lines compared with the control cell lines (T lymphocytic leukemia or Burkitt's lymphoma). Transfection with small interfering RNA into human AML cells established ZFAS1 knockdown. A cell-counting kit-8 (CCK-8) assay was used to investigate the effect of ZFAS1 on AML cell proliferation and the effect of ZFAS1 on the cell cycle and cell apoptosis was assessed using flow cytometry. Notably, the CCK-8 assay demonstrated that ZFAS1 knockdown inhibited cell proliferation in HL-60 and SKNO-1 cell lines and flow cytometry analysis indicated that ZFAS1 knockdown induced AML cell cycle G1 phase arrest and triggered cell apoptosis. Therefore, the present study indicated that ZFAS1 promoted the proliferation and inhibited the apoptosis of AML cells.

Long Noncoding RNAs as Biomarkers in Cancer

Long noncoding RNAs (lncRNAs) are a relatively well-characterized class of noncoding RNA (ncRNA) molecules, involved in the regulation of various cell processes, including transcription, intracellular trafficking, and chromosome remodeling. Their deregulation has been associated with the development and progression of various cancer types, the fact which makes them suitable as biomarkers for cancer diagnosis and prognosis. In recent years, detection of cancer-associated lncRNAs in body fluids of cancer patients has proven itself as an especially valuable method to effectively diagnose cancer. Cancer diagnosis and prognosis employing circulating lncRNAs are preferential when compared to classical biopsies of tumor tissues, especially due to their noninvasiveness, and have great potential for routine usage in clinical practice. Thus, this review focuses on summarizing the perspectives of lncRNAs as biomarkers in cancer, based on evaluating their expression profiles determined in body fluids of cancer patients.