The lncRNA CRNDE promotes colorectal cancer cell proliferation and chemoresistance via miR-181a-5p-mediated regulation of Wnt/β-catenin signaling

Prognostic Value of Long Noncoding RNA CRNDE as a Novel Biomarker in Solid Cancers: An Updated Systematic Review and Meta-Analysis

Background: Long noncoding RNA colorectal neoplasia differentially expressed (CRNDE) has been reported to exhibit a potential oncogenic role in the development of human cancers. However, the clinical value of CRNDE expression in various cancers still remains unclear. Herein, we conducted a meta-analysis to investigate the association between CRNDE and clinical outcomes in solid cancers.

Methods: A systematic search was performed though the PubMed, EMBASE, Web of Science, Ovid, Cochrane library, CNKI and WanFang databases for eligible studies on clinical values of CRNDE in solid cancers. The pooled hazard ratios (HRs) or odd ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the link between CRNDE and clinical outcomes.

Results: A total of 3690 patients from 20 studies (including 2 studies have 2 cohorts, respectively) were included. The results suggested that elevated CRNDE expression predicted a poor overall survival (OS) for in 13 types of solid cancers (HR=1.46, 95% CI: 1.33-1.58, P<0.001) with no heterogeneity (I²=21.8%, P=0.19). Subgroup analysis indicated a significant association between high CRNDE expression and shorter OS in the studies with digestive system cancers (HR=1.42, 95% CI: 1.28-1.55, P<0.001), qRT-PCR method (HR=1.45, 95% CI: 1.30-1.59, P<0.001), sample size >100 (HR=1.44, 95% CI: 1.32-1.57, P<0.001), and NOS>7 (HR= 1.50, 95% CI: 1.23-1.78, P<0.001). Furthermore, the pooled results showed that CRNDE was an independent prognostic factor for OS in cancer patients (HR=1.37, 95% CI: 1.22-1.52, P<0.001). In addition, we also revealed that CRNDE was positively related to tumor size (OR=2.10, 95%CI: 1.68-2.63, P<0.001), TNM stage (OR=2.86, 95%CI: 2.29-3.56, P<0.001), lymph node metastasis (LNM) (OR=3.21, 95%CI: 2.01-5.13, P<0.001), and distant metastasis (OR=4.36, 95%CI: 2.36-8.07, P<0.001). Although the probable evidences of publication bias were found in the studies with OS, tumor size, TNM stage or LNM, the trim and fill analysis confirmed the reliability of these results was not affected.

Conclusion: Elevated CRNDE expression was associated with larger tumor size, advanced TNM stage, worse LNM and distant metastasis, and shorter OS, suggesting that CRNDE may act as an independent prognostic biomarker in solid cancers.

Interactions among lncRNAs, miRNAs and mRNA in colorectal cancer

Long non-coding RNAs (lncRNAs) are longer than 200 nts non-coding transcripts and have recently emerged as one of the largest and significantly diverse RNA families whereas microRNAs (miRNAs) are highly conserved short single-stranded ncRNAs (∼18-22 nucleotides). As families of small and long evolutionarily conserved ncRNAs, lncRNAs activate and repress genes via a variety of mechanisms at both transcriptional and translational levels, while miRNAs regulate protein-coding gene expression mainly through mRNA degradation or silencing, These ncRNAs have been proved to be involved in multiple biological functions, such as proliferation, differentiation, migration, angiogenesis and apoptosis. Today, while majority of studies have focused on defining the regulatory functions of lncRNAs and miRNAs, limited information have now available for the mutual regulations of lncRNAs, miRNAs and mRNA. Thus, the underlying molecular mechanisms, in particularly the interactions among lncRNAs, miRNAs and mRNA in development, growth, metastasis and therapeutic potential of cancer still remain obscure. Colorectal cancer (CRC) is known as the third most common and fourth leading cancer death worldwide. Increasing evidence showed the close correlations among aberrant expressions of lncRNAs, miRNAs and the occurrence, development of CRC. This review summarize the potential links among these RNAs in following three areas: 1, The biogenesis and roles of miRNAs in CRC; 2, The biogenesis and functions of lncRNAs in CRC; 3, The interactions among lncRNAs, miRNAs and mRNA in tumorigensis, growth, progression, EMT formation, chemoradiotherapy resistance, and therapeutic potential in CRC. We believe that identifying diverging lncRNAs, miRNAs and relevant genes, their interactions and complex molecular regulatory networks will provide important clues for understanding the mechanism and developing novel diagnostic and therapeutic strategies for CRC. Further efforts are warranted to bring the promise of regulating their activities into clinical utilities.

MiR-423-5p inhibition alleviates cardiomyocyte apoptosis and mitochondrial dysfunction caused by hypoxia/reoxygenation through activation of the wnt/β-catenin signaling pathway via targeting MYBL2

MicroRNA (miR) plays an integral role in cardiovascular diseases. M-iR-423-5p is aberrantly expressed in patients with myocardial infarction and heart failure. The aim of the present study was to study the roles and mechanisms of miR-423-5p in hypoxia/reoxygenation (H/R) mediated cardiomyocytes injury. H9C2 cells were transfected with negative control, miR-423-5p mimic, and inhibitor for 48 hr, followed by exposed to H/R condition. Cell apoptosis rate, caspase 3/7 activities, Bax and cleaved-caspase 3 (c-caspase 3) protein levels were assayed by flow cytometry, Caspase-Glo 3/7 Assay kit, western blot analysis, respectively. Furthermore, the mitochondrial membrane potential, adenosine triphosphate (ATP) content, reactive oxygen species (ROS) production, and Drp1 expression were also investigated. Furthermore, the dual-luciferase reporter assay was used to evaluate the relationship between miR-423-5p and Myb-related protein B (MYBL2). The roles of miR-423-5p in wnt/β-catenin were assessed by western blot analysis. The results revealed that H/R triggered miR-423-5p expression. Overexpression of miR-423-5p promoted cardiomyocyte apoptosis, enhanced the activities of caspase 3/7, upregulated the expression of Bax and c-caspase 3. miR-423-5p upregulation caused the loss of mitochondrial membrane potential and the reduction of ATP content, the augment of ROS production and Drp1 expression. However, the opposite trends were observed upon suppression of miR-423-5p. In addition, miR-423-5p could target the 3' untranslated region of MYBL2. miR-423-5p depletion led to the activation of the wnt/β-catenin signaling pathway via targeting MYBL2. Knockdown of MYBL2 was obviously reversed the roles of miR-423-5p in apoptosis and mitochondrial dysfunction. Taken together, miR-423-5p suppression reduced H/R-induced cardiomyocytes injury through activation of the wnt/β-catenin signaling pathway via targeting MYBL2 in cardiomyocytes.

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.

FOXO1-regulated lncRNA LINC01197 inhibits pancreatic adenocarcinoma cell proliferation by restraining Wnt/β-catenin signaling

Background

Recent studies have revealed that numerous oncogenic long non-coding RNAs (lncRNAs) play pivotal roles in pancreatic ductal adenocarcinoma (PDAC) progression, but little is known about tumor-suppressive lncRNAs in PDAC. This study was conducted to evaluate the function of tumor-suppressive LINC01197 in PDAC progression and investigate the detailed mechanisms.

Methods

LncRNA microarray was used to identify differentially expressed lncRNAs in FOXO1-overexpressing PANC1 cells. LINC01197 expression was evaluated by quantitative PCR, Northern blotting, and fluorescence in situ hybridization. The Cancer Genome Atlas database was used to analyze the prognostic role of LNC01197 in PDAC. A luciferase reporter assay was performed to confirm the interaction between LNC01197 and FOXO1. The biological function of LINC01197 was evaluated by colony formation assay in vitro and in an animal subcutaneous tumorigenesis experiment and Ki67 staining in vivo. RNA-pulldown, western blotting, RNA immunoprecipitation assay, and co-immunoprecipitation were further performed to determine the molecular mechanism of LNC01197 and β-catenin in the Wnt pathway.

Results

We found that a FOXO1-related lncRNA, LINC01197, was significantly decreased in PDAC malignant tissues and that its low expression predicted poor prognosis. Moreover, LINC01197 was mainly localized in the nucleus and inhibited PDAC cell proliferation both in vitro and in vivo. Mechanistically, LINC01197 was found to bind to β-catenin and inhibit Wnt/β-catenin signaling activity by disrupting β-catenin binding to TCF4 in PDAC cells.

Conclusions

The novel FOXO1/LINC01197/β-catenin axis was dysregulated during PDAC progression. Our study provides insight into the mechanisms of LINC01197 in PDAC and reveal a potential target for PDAC clinical therapy and prognostic prediction.

LncRNA KCNQ1OT1 enhanced the methotrexate resistance of colorectal cancer cells by regulating miR-760/PPP1R1B via the cAMP signalling pathway

We aimed to explore the mechanism of the KCNQ1OT1/miR‐760/PPP1R1B axis acting to regulate methotrexate (MTX) resistance of colorectal cancer (CRC). Differentially expressed mRNAs and lncRNAs in MTX‐sensitive CRC cell lines and MTX‐resistant cell lines were determined through microarray analysis. Application of bioinformatics analysis was aimed to uncover the relationships among the lncRNAs/miRNAs/mRNAs, and to demonstrate the effects of cAMP signalling pathway in MTX‐resistant CRC. The expression level of RNA and proteins was, respectively, detected using qRT‐PCR and Western blot assays, whereas the dual‐luciferase reporter gene assay was implemented to verify the targeted relationship. The influence of the lncRNA/miRNA/mRNA axis on biological functions of MTX‐resistant cells and on the growth of tumours determined through both vitro and vivo experiments. LncRNA KCNQ1OT1 and PPP1R1B mRNA were overexpressed in MTX‐resistant CRC tumour cells. KCNQ1OT1 functioned as a sponge of miR‐760, which targeted PPP1R1B. Knockdown of KCNQ1OT1 enhanced chemosensitivity towards MTX through the sponging of miR‐760. MiR‐760 expressed at low levels targeted PPP1R1B in the activated cAMP signalling pathway under MTX treatment. Knockdown of KCNQ1OT1 dampened the proliferation of MTX‐resistant (HT29/MTX) cells by regulating the miR‐760/PPP1R1B axis, which also induced cell cycle arrest together with apoptosis. KCNQ1OT1 regulated the expression of PPP1R1B and the downstream genes CREB and CBP in the cAMP signalling pathway. MTX showed a suppressive function on CRC progression. KCNQ1OT1 enhanced the MTX resistance of CRC cells by regulating miR‐760‐mediated PPP1R1B expression via the cAMP signalling pathway.

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.

lncRNA Colorectal Neoplasia Differentially Expressed (CRNDE) Promotes Proliferation and Inhibits Apoptosis in Non-Small Cell Lung Cancer Cells by Regulating the miR-641/CDK6 Axis

BACKGROUND The lncRNA Colorectal Neoplasia Differentially Expressed (CRNDE) gene has been reported as a potential oncogene in NSCLC. Nevertheless, the molecular mechanism of CRNDE in NSCLC progression remains largely unknown. MATERIAL AND METHODS qRT-PCR assay was performed to detect the expression levels of CRNDE, miR-641, and cyclin-dependent kinase 6 (CDK6) in NSCLC. Western blot assay was employed to assess CDK6 protein level in treated NSCLC cells. si-CRNDE#1, si-CRNDE#2, miR-641 mimics, miR-641 inhibitors, or Vector-CDK6 were transfected into NSCLC cells to change the expression levels of CRNDE, miR-641, or CDK6. Dual-luciferase reporter assay was performed to validate the direct interrelated miRNA of CRNDE and the potential target of miR-641. MTT and flow cytometry assays were performed to assess the capacities of cell proliferation and apoptosis, respectively. RESULTS CRNDE level was upregulated in NSCLC, and its knockdown suppressed NSCLC cells proliferation and enhanced apoptosis, whereas miR-641 antagonized the regulatory effect of CRNDE knockdown by directly binding to CRNDE. Moreover, CDK6 was a target of miR-641 and miR-641 exerted anti-proliferation and pro-apoptosis effects through CDK6. CONCLUSIONS CRNDE promoted proliferation and inhibited apoptosis of NSCLC cells at least in part by regulating the miR-641/CDK6 axis, suggesting that CRNDE is a potential therapeutic target for NSCLC treatment.

ncRNAs associated with drug resistance and the therapy of digestive system neoplasms

Digestive system cancer remains a common cancer and the main cause of cancer-related death worldwide. Drug resistance is a major challenge in the therapy of digestive system cancer, and represents a primary obstacle in the treatment of cancer by restricting the efficiency of both traditional chemotherapy and biological therapies. Existing studies indicate that noncoding RNAs play an important role in the evolution and progression of drug resistance in digestive system cancer, mainly by modulating drug transporter-related proteins, DNA damage repair, cell-cycle-related proteins, cell apoptosis-related proteins, drug target-related proteins, and the tumor microenvironment. In this review, we address the potential mechanisms of ncRNAs underlying drug resistance in digestive system tumors and discuss the possible application of ncRNAs against drug resistance in digestive system tumors.

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.

Interference of the long noncoding RNA CDKN2B-AS1 upregulates miR-181a-5p/TGFβI axis to restrain the metastasis and promote apoptosis and senescence of cervical cancer cells

Long noncoding RNA (lncRNA) CDKN2B-AS1 has been shown to play a crucial role in the development as well as in the prognosis of various human cancers, including cervical cancer. However, the underlying mechanisms need to be further explored between CDKN2B-AS1 and cervical cancer. In the present study, RT-PCR showed that the mRNA level of CDKN2B-AS1 was significantly upregulated while the miR-181a-5p was downregulated in cervical cancer cell lines. In addition, the interference of CDKN2B-AS1 by shRNA resulted in the suppression of cell proliferation, invasion, migration and promotion of apoptosis and senescence, and either CDKN2B-AS1 overexpression or miR-181a-5p showed reversed results. Further studies demonstrated that CDKN2B-AS1 could directly interact with miR-181a-5p, and that there was an inverse correlation between miR-181a-5p and CDKN2B-AS1. In addition, we found that TGFβI was a target of miR-181a-5p and could be downregulated by CDKN2B-AS1 knockdown. Moreover, the in vivo experiments further demonstrated the contribution of CDKN2B-AS1 in cervical cancer including tumor growth, apoptosis inhibition and senescence inhibition, and CDKN2B-AS1 knockdown could inhibit the aforementioned activities. In summary, our study demonstrated that the CDKN2B-AS1/miR-181a-5p/TGFβI axis might play a vital role in cervical cancer development.

Atractylenolide II reverses the influence of lncRNA XIST/miR-30a-5p/ROR1 axis on chemo-resistance of colorectal cancer cells

This investigation was conducted to elucidate whether atractylenolide II could reverse the role of lncRNA XIST/miR-30a-5p/ROR1 axis in modulating chemosensitivity of colorectal cancer cells. We totally collected 294 pairs of colorectal cancer tissues and adjacent normal tissues and also purchased colorectal cancer cell lines and human embryonic kidney cell line. 5-fluorouracil, cisplatin, mitomycin and adriamycin were designated as the chemotherapies for colorectal cell lines, and atractylenolides were arranged as the Chinese drug. The expressions of XIST, miR-30a-5p and ROR1 were quantified with aid of qRT-PCR or Western blot, and luciferase reporter gene assay was implemented to determine the relationships among XIST, miR-30a-5p and ROR1. Our results demonstrated that XIST and ROR1 expressions were dramatically up-regulated, yet miR-30a-5p expression was down-regulated within colorectal cancer tissues (P < 0.05). The overexpressed XIST and ROR1, as well as under-expressed miR-30a-5p, were inclined to promote viability and proliferation of colorectal cells under the influence of chemo drugs (P < 0.05). In addition, XIST could directly target miR-30a-5p, and ROR1 acted as the targeted molecule of miR-30a-5p. Interestingly, atractylenolides not only switched the expressions of XIST, miR-30a-5p and ROR1 within colorectal cancer cells but also significantly intensified the chemosensitivity of colorectal cancer cells (P < 0.05). Finally, atractylenolide II was discovered to slow down the viability and proliferation of colorectal cancer cells (P < 0.05). In conclusion, the XIST/miR-30a-5p/ROR1 axis could be deemed as pivotal markers underlying colorectal cancer, and administration of atractylenolide II might improve the chemotherapeutic efficacy for colorectal cancer.

Long noncoding RNAs biomarker-based cancer assessment

Cancer diagnosis have mainly relied on the incorporation of molecular biomarkers as part of routine diagnostic tool. The molecular alteration ranges from those involving DNA, RNA, noncoding RNAs (microRNAs and long noncoding RNAs [lncRNAs]) and proteins. lncRNAs are recently discovered noncoding endogenous RNAs that critically regulates the development, invasion, and metastasis of cancer cells. They are dysregulated in different types of malignancies and have the potential to serve as diagnostic markers for cancer. The expression of noncoding RNAs is altered following many diseases, and besides, some of them can be secreted from the cells into the circulation following the apoptotic and necrotic cell death. These secreted noncoding RNAs are known as cell free RNA. These RNAs can be secreted from the cell through the apoptotic body, extracellular vesicles including microvesicle and exosome, and bind to proteins. Since, lncRNAs display high organ and cell specificity, can be found in the blood, urine, tumor tissue, or other tissues or bodily fluids of some patients with cancer, this review summarizes the most significant and up-to-date findings of research on lncRNAs involvement in different cancers, focusing on the potential of cancer-related lncRNAs as biomarkers for diagnosis, prognosis, and therapy.

Long non-coding RNA CRNDE regulates cell proliferation, migration, invasion, epithelial-mesenchymal transition and apoptosis in oral squamous cell carcinoma

The present study aimed to investigate whether the long non-coding RNA (lncRNA) colorectal neoplasia differentially expressed (CRNDE) can promote the migration and invasion of human oral squamous cell carcinoma (OSCC) cells via the regulation of epithelial-mesenchymal transition (EMT). CAL-27 and SCC-15 cells were classified into a control group, a small interfering negative control (si-NC) group (cells transfected with control siRNA) and an si-CRNDE group (cells transfected with CRNDE siRNA). The expression of CRNDE in OSCC tissues and cell lines was detected by in situ hybridization (ISH) and reverse transcription-quantitative polymerase chain reaction. An MTT assay was used to detect cell proliferation, flow cytometry was performed to determine cell apoptosis, wound-healing and Transwell assays were conducted to evaluate cell metastasis, and immunofluorescence staining and western blotting were performed to measure the expression of proteins associated with EMT. Tumor-bearing mouse models were established, and the tumor volumes were recorded. An immunohistochemical assay was performed to determine the expression of EMT-related proteins. CRNDE expression was increased in OSCC tissues and cell lines compared with that in normal tissues and cell lines. Compared with the control group, the si-CRNDE group displayed a reduction in the expression of CRNDE, in the proliferation, migration and invasion of cells, in the protein expression of N-cadherin, vimentin and Snail, and in the expression of proteins in the Wnt/β-catenin pathway. However, an increase was displayed in the apoptosis of cells and the expression of E-cadherin. Compared with the control group of tumor-bearing nude mice, the sh-CRNDE group demonstrated slowed tumor growth, reduced tumor weight and elevated E-cadherin, as well as reduced expression of N-cadherin, vimentin and Snail. In conclusion, silencing CRNDE may inhibit EMT, thus decreasing the migration and invasion of human OSCC cells by repressing the activation of the Wnt/β-catenin signaling pathway, thereby restricting cell growth and promoting cell apoptosis.

MEG3: an Oncogenic Long Non-coding RNA in Different Cancers

Long noncoding RNAs (lncRNAs) have recently considered as central regulators in diverse biological processes and emerged as vital players controlling tumorigenesis. Several lncRNAs can be classified into oncogenes and tumor suppressor genes depending on their function in cancer. A maternally expressed gene 3 (MEG3) gene transcripts a 1.6 kb lncRNA whose act as an antitumor component in different cancer cells, such as breast, liver, glioma, colorectal, cervical, gastric, lung, ovarian and osteosarcoma cancer cells. The present review highlights biological function of MEG3 to repress tumor through regulating the major tumor suppressor genes p53 and Rb, inhibiting angiogenesis-related factor, or controlling miRNAs. On the other hand, previous studies have also suggested that MEG3 mediates epithelial-mesenchymal transition (EMT). However, deregulation of MEG3 is associated with the  development and progression of cancer, suggesting that MEG3 may function as a potential biomarker and therapeutic target for human cancers.

lncRNA PLAC2 activated by H3K27 acetylation promotes cell proliferation and invasion via the activation of Wnt/β‑catenin pathway in oral squamous cell carcinoma

As a new group of important effector molecules involved in multiple cancer types, including breast cancer, lung cancer and oral squamous cell carcinoma, long noncoding RNAs (lncRNAs) have attracted considerable attention recently. However, the underlying cause that induces the dysregulated lncRNAs in cancer remains poorly understood. In the present study, the regulatory model of the lncRNA placenta-specific protein 2 (PLAC2) upregulation in oral squamous cell carcinoma (OSCC) was investigated and its biological functions in OSCC malignant progression was identified. A reverse transcription-quantitative polymerase chain reaction assay identified that PLAC2 is upregulated in OSCC cell lines and primary tissue samples. Furthermore, bioinformatic analysis followed by chromatin immunoprecipitation verified an enriched histone H3 on lysine 27 (H3K27) acetylation (H3K27ac) at the promoter region of the PLAC2 gene. Knockdown of cAMP-response element binding protein-binding protein (CBP) significantly reduced the enrichment level of H3K27ac, and thereby induced a decreased expression of PLAC2. Functionally, overexpression of PLAC2 promotes OSCC cell proliferation, migration and invasion, whereas knockdown of PLAC2 exerted an opposite effect. Furthermore, the Wnt/β-catenin signaling pathway was activated by PLAC2 and mediated the PLAC2-induced malignant progress of OSCC. In conclusion, the present results indicated that lncRNA PLAC2 is transcriptionally activated by H3K27ac modification at the promoter region in OSCC, and promotes cell growth and metastasis via activating Wnt/β-catenin signaling pathway. Therefore, PLAC2 may serve as a promising biomarker for OSCC prognosis and therapy.

Exosomes and their importance in metastasis, diagnosis, and therapy of colorectal cancer

Extracellular vesicles are known as actual intermediaries of intercellular communications, such as biological signals and cargo transfer between different cells. A variety of cells release the exosomes as nanovesicular bodies. Exosomes contain different compounds such as several types of nucleic acids and proteins. In this study, we focused on exosomes in colorectal cancer as good tools that can be involved in various cancer-related processes. Furthermore, we summarize the advantages and disadvantages of exosome extraction methods and review related studies on the role of exosomes in colorectal cancer. Finally, we focus on reports available on relations between mesenchymal stem cell-derived exosomes and colorectal cancer. Several cancer-related processes such as cancer progression, metastasis, and drug resistance of colorectal cancer are related to the cargoes of exosomes. A variety of molecules, especially proteins, microRNAs, and long noncoding RNAs, play important roles in these processes. The microenvironment features, such as hypoxia, also have very important effects on the properties of the origin cell-derived exosomes. On the other hand, exosomes derived from colorectal cancer cells also interfere with cancer chemoresistance. Furthermore, today it is known that exosomes and their contents can likely be very effective in noninvasive colorectal cancer diagnosis and therapy. Thus, exosomes, and especially their cargoes, play different key roles in various aspects of basic and clinical research related to both progression and therapy of colorectal cancer.

An experimental strategy unveiling exosomal microRNAs 486-5p, 181a-5p and 30d-5p from hypoxic tumour cells as circulating indicators of high-risk rectal cancer

Tumour hypoxia contributes to poor treatment outcome in locally advanced rectal cancer (LARC) and circulating extracellular vesicles (EVs) as potential biomarkers of tumour hypoxia and adverse prognosis have not been fully explored. We examined EV miRNAs from hypoxic colorectal cancer cell lines as template for relevant miRNAs in LARC patients participating in a prospective biomarker study (NCT01816607). Five cell lines were cultured under normoxia (21% O₂) or hypoxia (0.2% O₂) for 24 h, and exosomes were isolated by differential ultracentrifugation. Using a commercial kit, exosomes were precipitated from 24 patient plasma samples collected at the time of diagnosis. Exosome size distribution and protein cargo were determined by cryo-electron microscopy, nanoparticle tracking analysis, immunoblotting and flow cytometry. The vesicles harboured strong cell line-specific miRNA profiles with 35 unique miRNAs differentially expressed between hypoxic and normoxic cells. Six of these miRNAs were considered candidate-circulating markers of tumour hypoxia in the patients based on the frequency or magnitude of variance in hypoxic versus normoxic cell line experiments and prevalence in patient plasma. Of these, low plasma levels of exosomal miR-486-5p and miR-181a-5p were associated with organ-invasive primary tumour (p = 0.029) and lymph node metastases (p = 0.024), respectively, both attributes of adverse LARC prognosis. In line with this, the plasma level of exosomal miR-30d-5p was elevated in patients who experienced metastatic progression (p = 0.036). Our strategy confirmed that EVs from colorectal cancer cell lines were exosomes containing the oxygen-sensitive miRNAs 486-5p, 181a-5p and 30d-5p, which were retrieved as circulating markers of high-risk LARC.

Factors Regulating microRNA Expression and Function in Multiple Myeloma

Intensive research has been undertaken during the last decade to identify the implication of microRNAs (miRNAs) in the pathogenesis of multiple myeloma (MM). The expression profiling of miRNAs in MM has provided relevant information, demonstrating different patterns of miRNA expression depending on the genetic abnormalities of MM and a key role of some miRNAs regulating critical genes associated with MM pathogenesis. However, the underlying causes of abnormal expression of miRNAs in myeloma cells remain mainly elusive. The final expression of the mature miRNAs is subject to multiple regulation mechanisms, such as copy number alterations, CpG methylation or transcription factors, together with impairment in miRNA biogenesis and differences in availability of the mRNA target sequence. In this review, we summarize the available knowledge about the factors involved in the regulation of miRNA expression and functionality in MM.

Long noncoding RNA SNHG6 functions as a competing endogenous RNA by sponging miR-181a-5p to regulate E2F5 expression in colorectal cancer

Background

Long noncoding RNAs (lncRNAs) have been identified as a novel class of regulators implicated in diverse biological processes in human cancers. Currently, evidence have shown that SNHG6, a cancer-associated lncRNA, exerts critical functions in gastric cancer and hepatocellular carcinoma; however, its role in colorectal cancer (CRC) remains unclear.

Methods

The expression of SNHG6 was determined by quantitative real-time PCR in CRC tissues and cells. SNHG6 was downregulated by using RNAi technology. Cell proliferation was examined by MTT and clone formation assays. Cell migration and invasion were determined by wound healing and transwell assays. Fluorescence in situ hybridization assays were performed to examine subcellular localization of SNHG6 in CRC cells. Fluorescence reporter and Western blot assays were used to explore the potential mechanisms of SNHG6 in CRC progression.

Results

In this study, we found that SNHG6 was significantly upregulated in CRC tissues and cell lines, compared with normal tissues and normal colorectal epithelial cell line NCM460, respectively. High expression of SNHG6 was positively correlated with tumor size, advanced TNM stage, and distant metastasis. Survival analyses revealed that SHNG6 was significantly associated with poor clinical outcomes and could serve as an independent prognostic factor. Loss-of-function studies demonstrated that SNHG6 knockdown inhibited CRC cell proliferation, induced G0/G1 arrest, promoted apoptosis, suppressed CRC cell migration and invasion, and restrained tumor growth. Mechanistic investigations showed that SNHG6 acted as a competing endogenous RNA for miR-181a-5p and attenuated the inhibitory effect of miR-181a-5p on E2F5.

Conclusion

Taken together, these results demonstrated that SNHG6 plays a crucial role in CRC progression via miR-181a-5p/E2F5 axis. Therefore, SNHG6 may serve as a prognostic and therapeutic biomarker in CRC.

Activation of LncRNA TINCR by H3K27 acetylation promotes Trastuzumab resistance and epithelial-mesenchymal transition by targeting MicroRNA-125b in breast Cancer

BACKGROUND

Trastuzumab resistance followed by metastasis is a major obstacle for improving the clinical outcome of patients with advanced human epidermal growth factor receptor 2-positive (HER-2+) breast cancer. While long non-coding RNAs (lncRNAs) can modulate cell behavior, the contribution of these RNAs in trastuzumab resistance and metastasis of HER-2+ breast cancer is not well known. In this study, we sought to identify the regulatory role of lncRNA in trastuzumab resistance and accompanied Epithelial-mesenchymal Transition (EMT) process in advanced HER-2+ breast cancer.

METHODS

Trastuzumab-resistant SKBR-3-TR and BT474-TR cell lines were established by grafting SKBR-3 and BT474 cells into mouse models and subjected to trastuzumab treatment. LncRNA microarray followed by quantitative reverse transcription PCR (qRT-PCR) was carried out to verify the differentially expressed lncRNAs. Western blotting, bioinformatics analysis, immunofluorescence assay and immunoprecipitation assays (ChIP and RIP) were performed to identify the involvement and functional interactions between H3K27 acetylation and terminal differentiation-induced non-coding RNA (TINCR) or between TINCR and its downstream genes including miR-125b, HER-2 and Snail-1. In addition, a series of in vitro and in vivo assays were performed to assess the functions of TINCR.

RESULTS

An increase in both, IC50 value of trastuzumab and EMT was observed in the established trastuzumab-resistant cell lines. The expression level of TINCR was significantly increased in trastuzumab-resistant cells when compared with sensitive cells. Knockdown of TINCR reversed the trastuzumab resistance and the acquired EMT in these cells. TINCR was detected in the cytoplasm of breast cancer cells and could sponge miR-125b, thereby releasing HER-2 and inducing trastuzumab resistance. In addition, Snail-1 was found to be the target gene of miR-125b and overexpression of Snail-1 could reverse the suppressed migration, invasion, and EMT caused by TINCR silencing. The upregulation of TINCR in breast cancer was attributed to the CREB-binding protein (CBP)-mediated H3K27 acetylation at the promoter region of TINCR. Clinically, HER-2+ breast cancer patients with high TINCR expression levels were associated with poor response to trastuzumab therapy and shorter survival time.

CONCLUSION

TINCR could promote trastuzumab resistance and the accompanied EMT process in breast cancer. Therefore, TINCR might be a potential indicator for prognosis and a therapeutic target to enhance the clinical efficacy of trastuzumab treatment.

Analyzing the Interactions of mRNAs and ncRNAs to Predict Competing Endogenous RNA Networks in Osteosarcoma Chemo-Resistance

Chemo-resistance is a huge obstacle encountered in the osteosarcoma (OS) treatment. Protein-coding mRNAs, as well as non-coding RNAs (ncRNAs), including long ncRNA (lncRNA), circular RNA (circRNA), and microRNA (miRNA), have been demonstrated to play an essential role in the regulation of cancer biology. However, the comprehensive expression profile and competing endogenous RNA (ceRNA) regulatory network between mRNAs and ncRNAs in the OS chemo-resistance still remain unclear. In the current study, we developed whole-transcriptome sequencing (RNA sequencing [RNA-seq]) in the three paired multi-drug chemo-resistant and chemo-sensitive OS cell lines to comprehensively identify differentially expressed lncRNAs, circRNAs, miRNAs, and mRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed for mRNAs with significantly different expression. Then the ceRNA networks combining lncRNAs, circRNAs, miRNAs, and mRNAs were predicted and constructed on the basis of the authoritative miRanda and TargetScan databases combined with the widely accepted vital drug resistance-related genes and signal transduction pathways. In addition, two constructed ceRNA regulatory pathways, lncRNAMEG3/hsa-miR-200b-3p/AKT2 and hsa_circ_0001258/hsa-miR-744-3p/GSTM2, were randomly selected and validated by real-time qPCR, RNA immunoprecipitation (RIP), RNA pull-down assay, and dual luciferase reporter gene system. Taken together, our findings may provide new evidence for the underlying mechanism of OS chemo-resistance and uncover some novel targets for reversing it.

Long non-coding RNA RUNX1-IT1 plays a tumour-suppressive role in colorectal cancer by inhibiting cell proliferation and migration

Long non-coding RNAs (lncRNAs) have been demonstrated to be involved in the progression of various cancers. In this study, we aim to investigate the role of lncRNA RUNX1-IT1 in the development of colorectal cancer (CRC). The expression levels of lncRNA RUNX1-IT1 were measured using quantitative real-time Polymerase Chain Reaction(qRT-PCR). CCK8 proliferation assay, transwell assay, and flow cytometry were performed to evaluate the effect of lncRNA RUNX1-IT1 on CRC cell proliferation, migration, and apoptosis. The proliferation markers (PCNA, Ki67), apoptosis markers (cleaved-PARP, cleaved-caspase3), and MMP9 are detected by western blotting. Significant down regulation of lncRNA RUNX1-IT1 was measured in CRC tissues and three CRC cell lines (HCT116, HT29, and RKO) compared with paired nontumorous adjacent tissues (P < 0.01) or the normal colonic epithelial cell line FHC (P < 0.05), respectively. Moreover, the proliferative and migration potential of CRC cells were inhibited by overexpressing lncRNA RUNX1-IT1, which could be obviously improved by knocking down lncRNA RUNX1-IT1. The protein levels of PCNA, Ki67, and MMP9 were upregulated by overexpressing lncRNA RUNX1-IT1 and down regulated in si-RUNX1-IT1 cells. Besides, lncRNA RUNX1-IT1 could also promote the apoptosis of CRC cells. In conclusion, lncRNA RUNX1-IT1 is downregulated in CRC and plays a tumour-suppressive role due to the regulatory of cell proliferation, migration, and apoptosis. SIGNIFICANCE OF THE STUDY: We demonstrated that lncRNA RUNX1-IT1 was down regulated both in CRC tissues and cell lines. Besides, lncRNA RUNX1-IT1 could serve as a potential diagnostic biomarker and play a tumour-suppressive role owing to its good diagnostic efficacy and inhibition of CRC cell proliferation and migration.

Differential microRNA expression in cultured palatal fibroblasts from infants with cleft palate and controls

Background

The role of microRNAs (miRNAs) in animal models of palatogenesis has been shown, but only limited research has been carried out in humans. To date, no miRNA expression study on tissues or cells from cleft palate patients has been published. We compared miRNA expression in palatal fibroblasts from cleft palate patients and age-matched controls.

Material and Methods

Cultured palatal fibroblasts from 10 non-syndromic cleft lip and palate patients (nsCLP; mean age: 18 ± 2 months), 5 non-syndromic cleft palate only patients (nsCPO; mean age: 17 ± 2 months), and 10 controls (mean age: 24 ± 5 months) were analysed with next-generation small RNA sequencing. All subjects are from Western European descent. Sequence reads were bioinformatically processed and the differentially expressed miRNAs were technically validated using quantitative reverse-transcription polymerase chain reaction (RT-qPCR).

Results

Using RNA sequencing, three miRNAs (hsa-miR-93-5p, hsa-miR-18a-5p, and hsa-miR-92a-3p) were up-regulated and six (hsa-miR-29c-5p, hsa-miR-549a, hsa-miR-3182, hsa-miR-181a-5p, hsa-miR-451a, and hsa-miR-92b-5p) were down-regulated in nsCPO fibroblasts. One miRNA (hsa-miR-505-3p) was down-regulated in nsCLP fibroblasts. Of these, hsa-miR-505-3p, hsa-miR-92a, hsa-miR-181a, and hsa-miR-451a were also differentially expressed using RT-PCR with a higher fold change than in RNAseq.

Limitations

The small sample size may limit the value of the data. In addition, interpretation of the data is complicated by the fact that biopsy samples are taken after birth, while the origin of the cleft lies in the embryonic period. This, together with possible effects of the culture medium, implies that only cell-autonomous genetic and epigenetic differences might be detected.

Conclusions

For the first time, we have shown that several miRNAs appear to be dysregulated in palatal fibroblasts from patients with nsCLP and nsCPO. Furthermore, large-scale genomic and expression studies are needed to validate these findings.

20(S)-ginsenoside-Rg3 reverses temozolomide resistance and restrains epithelial-mesenchymal transition progression in glioblastoma

Glioblastoma multiforme (GBM) is one of the most malignant human intracranial tumors. Temozolomide (TMZ) is the primary alkylating agent for GBM patients. However, many GBM patients are resistant to TMZ. Therefore, patients with GBM urgently need more effective therapeutic options. 20(S)‐ginsenoside‐Rg3 (20(S)‐Rg3) is a natural chemical with anti‐tumor effects, but at present there is little understanding of its functional mechanism. Several research reports have demonstrated that O⁶‐methylguanine DNA‐methyltransferase (MGMT) repairs damaged DNA and contributes to TMZ resistance in gliomas. In addition, recent studies have shown that MGMT gene expression could be regulated by the Wnt/β‐catenin pathway. However, whether 20(S)‐Rg3 inhibits MGMT expression and augments chemosensitivity to Temozolomide (TMZ) in glioma cells remains unclear. In this study, we explored the modulating effects of 20(S)‐Rg3 on MGMT. We used glioma cell lines, primary cell strain (including T98G, U118 and GBM‐XX; all of them are MGMT‐positive glioma cell lines) and xenograft glioma models to examine whether 20(S)‐Rg3 increased the sensitivity to TMZ and to reveal the underlying mechanisms. We found that the MGMT expression was effectively downregulated by 20(S)‐Rg3 via the Wnt/β‐catenin pathway in glioma cell lines, and TMZ resistance was significantly reversed by 20(S)‐Rg3. Meanwhile, 20(S)‐Rg3 shows no obvious cytotoxicity at its effective dose and is well tolerated in vivo. In addition, we found that 20(S)‐Rg3 significantly restrains the epithelial‐mesenchymal transition (EMT) progression of glioma cells. Taken together, these results indicate that 20(S)‐Rg3 may be a novel agent to use in treatment of GBM, especially in TMZ‐resistant GBM with high MGMT expression.

Long noncoding RNA CRNDE promotes non-small cell lung cancer progression via sponging microRNA-338-3p

BACKGROUND

The long noncoding RNA colorectal neoplasia differentially expressed (CRNDE) was reported to be involved in the initiation and development of multiple cancers. However, the detailed biological role of CRNDE in non-small cell lung cancer (NSCLC) remains largely unclear. Herein, we aimed to explore the biological function and underlying molecular mechanism of CRNDE in NSCLC.

MATERIALS AND METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect the expression of CRNDE in NSCLC tissues and cell lines. Cell counting kit-8 (CCK-8), colony formation, flow cytometry, wound-healing, and transwell invasion assays were applied to detect cell proliferation, colony formation, cycle arrest progression, migration and invasion, respectively. Novel targets of CRNDE were selected with bioinformatics software and were confirmed using luciferase reporter and RNA immunoprecipitation assays. To detect the role of CRNDE in vivo tumorigenesis, tumor xenografts were created.

RESULTS

CRNDE expression is remarkably upregulated in NSCLC tissues and cell lines. Upregulated CRNDE expression was positively associated with advanced tumor-node-metastasis (TNM) stage, lymph node metastasis and poor overall survival of patients with NSCLC. Function assays demonstrated that knockdown of CRNDE significantly inhibited NSCLC cell proliferation, colony formation, migration and invasionin vitro, and decreased the xenograft tumor volume and weight in vitro. We uncovered that miR-338-3p is a downstream target of CRNDE and that miR-338-3p inhibition partially reversed the CRNDE depletion-mediated inhibitory effect on cell proliferation, colony formation, migration and invasion in NSCLC cells.

CONCLUSION

These findings indicated that CRNDE functions as an oncogene that exerts important regulatory roles in NSCLC progression via sponging miR-338-3p.

ANRIL promotes chemoresistance via disturbing expression of ABCC1 by regulating the expression of Let-7a in colorectal cancer

Increasing evidence indicates that long non-coding RNAs (lncRNAs) antisense non-coding RNA in the INK4 locus (ANRIL) has been involved in various diseases and promotes tumorigenesis and cancer progression as an oncogenic gene. However, the effect of ANRIL on chemoresistance remains still unknown in colorectal cancer (CRC). Here, we investigated ANRIL expression in 63 cases of colorectal cancer specimens and matched normal tissues. Results revealed that ANRIL was up-regulated in tumor tissues samples from patients with CRC and CRC cell lines. Increased ANRIL expression in CRC was associated with poor clinical prognosis. Kaplan–Meier analysis showed that ANRIL was associated with overall survival of patients with colorectal cancer, and patients with high ANRIL expression tended to have unfavorable outcome. In vitro experiments revealed that ANRIL knockdown significantly inhibited CRC cell proliferation, improved the sensitivity of chemotherapy and promoted apoptosis. Further functional assays indicated that ANRIL overexpression significantly promoted cell chemoresistance by regulating ATP-binding cassette subfamily C member 1 through binding Let-7a. Taken together, our study demonstrates that ANRIL could act as a functional oncogene in CRC, as well as a potential therapeutic target to inhibit CRC chemoresistance.

LncRNA MAFG-AS1 promotes the progression of colorectal cancer by sponging miR-147b and activation of NDUFA4

Researchers have shown that long noncoding RNAs (lncRNAs) are closely associated with the pathogenesis of colorectal cancer (CRC). In here, we aimed to explore the function of lncRNA MAFG-AS1 in tumorigenesis of CRC. Firstly, we found that the expression of MAFG-AS1 was upregulated in CRC tissues and positively correlated with the advanced tumor stage. A reciprocal repression was found between MAFG-AS1 and miR-147b. The expression of miR-147b was downregulated in CRC tissues and inversely correlated with MAFG-AS1. Both the low-expression of miR-147b expression and the advanced tumor stage were independent factor for poor survival probability. Furthermore, overexpression of MAFG-AS1 promoted cell proliferation, cell cycle progression, and invasion, and inhibited apoptosis, while transduction of miR-147b partially reversed the effect of MAFG-AS1 on cellular processes. Consistently, stable over-expression of MAFG-AS1 contributed to the growth of colon cancer cell xenografts in vivo. NDUFA4 was identified as a direct target of miR-147b and knockdown of NDUFA4 abolished the oncogenic role of miR-147b inhibitor. Besides, MAFG-AS1 contributed to cell glycolysis by sponging miR-147b and activation of NDUFA4, causing an upregulation of PDK1, PFK1 and PKM2. Taken together, our study suggested that MAFG-AS1 functions as a novel oncogenic lncRNA in the development of CRC by regulating miR-147b/NDUFA4.

Non-coding RNA NEAT1/miR-214-3p contribute to doxorubicin resistance of urothelial bladder cancer preliminary through the Wnt/β-catenin pathway

BACKGROUND

Urothelial bladder cancer (UBC) is one of the most lethal urological malignancies in the world. Patients with UBC are routinely given chemotherapy which results in a median survival of 12-15 months. Nuclear-enriched abundant transcript 1 (NEAT1) functions as an oncogene and could be used as a therapeutic target for human UBC. However, the involvement of NEAT1 in doxorubicin (DOX) resistance of UBC has been poorly demonstrated.

METHODS

Quantitative Real-time PCR (qRT-PCR) was used to detect the expression levels of NEAT1 and miR-214-3p in UBC tissues and cells. Bioinformatics prediction, RNA pull-down and qRT-PCR were used to assay the regulation manner of NEAT1 and miR-214-3p. Loss/gain function of NEAT1 and miR-214-3p together with western blot, drug resistance assay and flow cytometry were used to explore the influence of NEAT1 in DOX resistance was correlative with miR-214-3p. Finally, luciferase assay system was applied to determine the Wnt/β-catenin signal activity.

RESULTS

NEAT1 was upregulated and miR-214-3p was downregulated in DOX-resistant UBC tissues and cells. NEAT1 knockdown inhibited J82 and T24 cells to DOX chemosensitivity by negatively regulating miR-214-3p expression. NEAT1/miR-214-3p contributed to DOX resistance of UBC preliminary through the Wnt/β-catenin pathway.

CONCLUSION

NEAT1 contributed to DOX resistance of UBC through the Wnt/β-catenin pathway partly by negatively regulating miR-214-3p expression. Our findings will provide a promising ncRNA targeted therapeutic strategy for UBC with DOX resistance.

The long non-coding RNA CRNDE competed endogenously with miR-205 to promote proliferation and metastasis of melanoma cells by targeting CCL18

Melanoma was the most malignant skin neoplasm with an increasing morbidity around the world. Although new immunotherapies and targeted therapies have emerged recently, the long-term survival of melanoma patients still remains low. To reveal effective diagnostic methods and therapeutic strategies, the potential mechanism of melanoma is urgently needed to be studied. Long non-coding RNAs (lncRNAs) have become an important regulatory factor in the occurrence and development of cancer, and it can be used as a new prognostic and diagnostic marker. In this study, we aimed to inspect the effects of lncRNA colorectal neoplasia differentially expressed (CRNDE) on the melanoma cell viability, invasion and migration. After microarray analysis, 106 dysregulated lncRNAs and 1187 abnormally expressed mRNAs were screened out. Further, the lncRNA CRNDE and CCL18 expression in melanoma tissues and cell lines were examined. It was determined that they were both overexpressed in melanoma tissues and cell lines. The down-regulation of lncRNA CRNDE and CCL18 induced melanoma cell apoptosis and inhibited cell viability. Then, miR-205 which had binding site with lncRNA CRNDE and CCL18 was involved in the next experiment, and it was down-regulated in melanoma that negatively correlated with lncRNA CRNDE expression. In addition, overexpression of miR-205 results in the restore of cell viability and aggressiveness. In conclusion, LncRNA CRNDE promotes the migration and invasion of melanoma by sponging miR-205 and releasing CCL18.

Targeting Long Noncoding RNA in Glioma: A Pathway Perspective

Long noncoding RNAs (lncRNAs) participate extensively in biological processes of various cancers. The majority of these transcripts are uniquely expressed in differentiated tissues or specific cancer types. lncRNAs are aberrantly expressed in gliomas and exert diverse functions. In this article, we provided an overview of how lncRNAs regulate cellular processes in glioma, enumerated the lncRNAs that may act as glioma biomarkers, and showed their potential clinical implications.

The emerging role of long non-coding RNAs in the drug resistance of colorectal cancer

Colorectal cancer (CRC) remains one of the leading causes of cancer-related deaths in the world. Chemotherapy has been used to treat CRC patients in order to improve prognosis. Oxaliplatin and 5-Fluorouracil (5-FU) based chemotherapy is a first line treatment for locally advanced and metastatic CRC. For patients with wild-type KRAS metastatic CRC, cetuximab (an EGFR monoclonal antibody) is a commonly used targeted therapy. CRC is initially sensitive to chemotherapy and targeted therapy. However, drug resistance frequently arises, which significantly affect the treatment outcome in these patients. An increasing number of studies have indicated that lncRNAs are implicated in the drug resistance of CRC. This review aims to gain insights into the role and molecular mechanism of lncRNAs in CRC drug resistance.

Long non-coding RNA CRNDE in cancer prognosis: Review and meta-analysis

BACKGROUND

Colorectal neoplasia differentially expressed (CRNDE), a 1910-nt lncRNA encoded on human chromosome 16, has been found to be involved in various cancers. Nevertheless, the clinical and diagnostic values of CRNDE in tumors still need to be explored. In this review, we aimed to elucidate the clinical role of CRNDE in cancer by searching all correlative literature, and we sequentially explored the association between CRNDE levels and overall survival (OS) or clinicopathological characteristics of cancer.

METHODS

We conducted a database search of PubMed, Wanfang Data, Ovid, SinoMed, China National Knowledge Infrastructure, Cochrane Library, and Web of Science (up to January 1, 2018). The pooled odds ratio (OR) and hazard ratio (HR) were used to assess extents of correlation between CRNDE and cancer prognosis. After identification of the inclusion and exclusion criteria, 12 articles including 1361 patients were selected for this review.

RESULTS

The results suggested that high levels of CRNDE were highly related to poor OS in tumor patients, with pooled HRs of 2.314 (1.894-2.826, P < .001, fixed-effects model). Likewise, we also found that high CRNDE expression was correlated with high tumor stage [OR: 3.340, 95% confidence interval (CI): 2.417-4.616, P < .001, random-effects model] and lymph node metastasis (OR: 3.027, 95% CI: 2.071-4.425, P = .004, random-effects model).

CONCLUSIONS

Our findings demonstrated that CRNDE may modify susceptibility for various cancers and may serve as a new predictive factor for prognosis and diagnosis in different types of cancers.

Long non-coding RNA LINC01503 promotes colorectal cancer cell proliferation and invasion by regulating miR-4492/FOXK1 signaling

Increasing evidence indicates that long non-coding RNAs (lncRNAs) are closely associated with the progression of human cancer, including colorectal cancer (CRC). A previous study suggested that lncRNA LINC01503 promotes squamous cell carcinoma progression. However, the function of LINC01503 in CRC has remained elusive. The present study indicated that LINC01503 was significantly upregulated in CRC tissues compared with that in adjacent normal tissues as detected by reverse transcription-quantitative polymerase chain reaction. It was demonstrated that knockdown of long intergenic non-protein coding RNA (LINC)01503 markedly inhibited the proliferation and invasion of CRC cells, whereas overexpression of LINC01503 had the opposite effects, as indicated by Cell Counting kit-8 and Transwell assays. Mechanistically, it was revealed that LINC01503 serves as a sponge for microRNA (miR)-4492, which targets forkhead box K1 (FOXK1) in CRC cells. In addition, luciferase reporter assays demonstrated the direct binding of miR-4492 mimics to LINC01503 and to a sequence in the 3'-untranslated region of FOXK1. Furthermore, it was demonstrated that overexpression of LINC01503 reduced the availability of miR-4492 in CRC cells. Furthermore, miR-4492 mimics inhibited FOXK1 expression, while simultaneous overexpression of LINC01503 abolished this effect. Finally, it was demonstrated that restoration of FOXK1 abolished the inhibitory effect of LINC01503 knockdown on CRC cell proliferation and invasion. Taken together, the present results suggested that LINC01503 promotes CRC progression via acting as a competing endogenous RNA for miR-4492/FOXK1.

The role of microRNAs in 5-FU resistance of colorectal cancer: Possible mechanisms

Colorectal cancer (CRC) is one of the most common cancers globally. Despite recent advances in therapeutic approaches, this cancer continues to have a poor prognosis, particularly when diagnosed late. 5-Fluorouracil (5-FU) has been commonly prescribed for patients with CRC, but resistance to 5-FU is one of the main reasons for failure in the treatment of this condition. Recently, microRNAs (miRNAs) have been established as a means of modifying the signaling pathways involved in initiation and progression of CRC and their role as oncogene or tumor suppressor have been investigated in various studies. Moreover, miRNAs through various mechanisms play an important role in inducing tumor resistance or sensitivity to anticancer drugs. Detecting and targeting these mechanisms may be a new therapeutic approach. This review summarizes the current knowledge about the potential roles of miRNAs in 5-FU resistance, with particular emphasis on molecular mechanism involved.

LINC00312 represses proliferation and metastasis of colorectal cancer cells by regulation of miR-21

Long non‐coding RNAs (lncRNAs) have emerged as important regulators of cancer, including colorectal cancer (CRC). The exact expression pattern of long intergenic noncoding RNA 00312 (LINC00312) in CRC and its mechanisms of action have not been reported. Here, we found that LINC00312 is underexpressed in CRC tissues and cell lines. Functional experiments suggested that LINC00312 suppresses growth, migration and invasion of CRC cells in vitro and attenuates tumour proliferation and metastasis in vivo. Mechanistically, LINC00312 was found to regulate the malignancy of CRC cells by binding to miR‐21 and by functioning as a tumour suppressor targeting PTEN. Overexpression of miR‐21 or knockdown of PTEN attenuated the LINC00312‐mediated inhibition of CRC cell proliferation and invasion. Taken together, our results elucidate the role of the LINC00312–miR‐21–PTEN axis in CRC cell proliferation and tumour progression and may lead to new lncRNA‐based diagnostics or therapeutics for CRC.

LncRNA CRNDE is a biomarker for clinical progression and poor prognosis in clear cell renal cell carcinoma

Colorectal neoplasia differentially expressed (CRNDE) served as an oncogenic long noncoding RNA (lncRNA) to be involved in the initialization and development of human cancers. However, the clinical significance and biological function of CRNDE in clear cell renal cell carcinoma (ccRCC) was not fully understood. In our study, we found CRNDE levels were increased in ccRCC tissue specimens and cell lines, and corrected with advanced clinical stage, large tumor size, lymph node metastasis, distant metastasis, and poor pathological grade in patients with ccRCC. Furthermore, levels of CRNDE were negatively correlated with overall survival of patients with ccRCC, and high-expression of CRNDE was an independent poor prognostic factor for patients with ccRCC. Moreover, loss-of-function and gain-of-function approaches showed CRNDE-enhanced ccRCC cell migration and invasion through modulating EMT-associated genes. In conclusion, CRNDE acts as an oncogenic lncRNA in ccRCC.

Potential role of LINC00996 in colorectal cancer: a study based on data mining and bioinformatics

Background

The clinical significance of LINC00996 in colorectal cancer (CRC) has not been verified. In the current study, the authors aimed to explore the expression of LINC00996 and its clinical significance in CRC based on the data mining of Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) datasets, as well as to elucidate the functions of its potential target genes.

Materials and methods

GEO and TCGA microarray datasets were used to evaluate the LINC00996 expression and its clinical significance in CRC. LINC00996 related genes were identified by Multi Experiment Matrix, RNA-Binding Protein DataBase, and The Atlas of Noncoding RNAs in Cancer. Subsequently, they were sent to gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analysis.

Results

LINC00996 is significantly decreased in CRC tissues compared with non-tumor tissues. Low level of LINC00996 is associated with remote metastasis and poor overall survival. However, LINC00996 has a minimal effect on gender, lymphatic invasion, tumor size, lymph node metastasis, and pathological stage. One hundred and forty-two LINC00996 related genes were identified; the results of functional analysis indicated that LINC00996 might repress tumorigenesis and metastasis via modulating the JAK-STAT, NF-κB, HIF-1, TLR, and PI3K-AKT signaling pathways.

Conclusion

Our study demonstrates that decreased LINC00996 expression may be involved in colorectal carcinogenesis and metastasis, and the depletion of LINC00996 is associated with a poor outcome in CRC patients. Moreover, the JAK-STAT, NF-κB, HIF-1, TLR, and PI3K-AKT pathways may be the key pathways regulated by LINC00996 in CRC.

Long noncoding RNA kcna3 inhibits the progression of colorectal carcinoma through down-regulating YAP1 expression

Long non-coding RNAs (lncRNAs) regulate diverse cellular processes, and their anomalous expression exert an essential role in the progression of many kinds of cancers, including colorectal carcinoma (CRC). The objective of this study was to investigate the role of lncRNA kcna3 and its underlying mechanism in CRC progression. The expression of lncRNA kcna3 in human CRC tissues and the adjacent non-tumor tissues was evaluated by RT-PCR. The correlations between lncRNA kcna3 expression levels and the overall survival (OS), as well as the clinicopathological features of CRC patients were analyzed. Gain-of-function and loss-of-function experiments were used to evaluate the effects of lncRNA kcna3 on the proliferation, apoptosis, migration, invasion and tumorigenesis of colon cancer SW620 cells. We found that lncRNA kcna3 was lowly expressed in CRC tissues, and its low expression was closely associated with patients' higher TNM grade and the higher occurrence rate of lymphatic metastasis and distant metastasis, as well as shorter OS. Enhanced expression of lncRNA kcna3 inhibited SW620 cells' proliferation, migration and invasion, and induced cell apoptosis in vitro, and repressed CRC tumor growth in vivo. Whereas knockdown of lncRNA kcna3 showed the opposite results. Mechanistically, up-regulation of lncRNA kcna3 decreased YAP1 protein expression and accelerated its degradation. The effects of lncRNA kcna3 overexpression on cell growth and tumorigenesis inhibition and apoptosis promotion were weakened when the expression of YAP1 was up-regulated. In conclusion, this study revealed that lncRNA kcna3 exerts a tumor-inhibit role in CRC progression through down-regulating YAP1 expression, indicating that lncRNA kcna3/YAP1 might be served as a new prognostic biomarker and therapeutic target for CRC.

Linc-smad7 promotes myoblast differentiation and muscle regeneration via sponging miR-125b

Long noncoding RNAs (lncRNAs) are involved in the regulation of skeletal muscle development. In the present study, differentially expressed lncRNAs were identified from RNA-seq data derived from myoblasts and myotubes. We conducted studies to elucidate the function and molecular mechanism of action of Linc-smad7 during skeletal muscle development. Our findings show that Linc-smad7 is upregulated during the early phase of myoblasts differentiation. In in vitro studies, we showed that overexpression of Linc-smad7 promoted the arrest of myoblasts in G1 phase, inhibited DNA replication, and induced myoblast differentiation. Our in vivo studies suggest that Linc-smad7 stimulates skeletal muscle regeneration in cardiotoxin-induced muscle injury. Mechanistically, Linc-smad7 overexpression increased smad7 and IGF2 protein levels. On the contrary, overexpression of miR-125b reduced smad7 and IGF2 protein levels. Results of RNA immunoprecipitation analysis and biotin-labeled miR-125b capture suggest that Linc-smad7 could act as a competing endogenous RNA (ceRNA) for miRNA-125b. Taken together, our findings suggest that the novel noncoding regulator Linc-smad7 regulates skeletal muscle development.

Small nucleolar RNA host gene 1: A new biomarker and therapeutic target for cancers

OBJECTIVES

Long non-coding RNAs (lncRNAs), a group of transcripts with length greater than 200 nucleotides, have been involved in multiple pathophysiological processes of the human body, especially in tumorigenesis and progression of cancers. The aberrant expression of lncRNAs processes crucial functions involved in proliferation, apoptosis and metastatic capacity of cancers. Recent studies have revealed that small nucleolar RNA host gene 1 (SNHG1), a long non-coding RNA transcribed from UHG, was located in chromosome 11. Aberrant expression of SNHG1 has been demonstrated to be associated with various sites of cancers such as glioma, esophageal cancer, gastric cancer and many others, and its deregulation could be related to survival and prognosis of cancer patients. Pertinent to clinical practice, SNHG1 might act as a prognostic biomarker for tumors and might even serve as potential target for therapy. In this review, we summarized current researches concerning the role of SNHG1 in tumor progression and discussed its mechanisms involved.

MATERIALS AND METHODS

In this review, we summarized and figured out recent studies concerning the expression and biological mechanisms of SNHG1in tumor development. The related studies were obtained through a systematic search of PubMed, Embase and Cochrane Library.

RESULTS

SNHG1 was a valuable cancer-related lncRNA that the expression level was up-regulation in a variety of malignancies, including glioma, esophageal cancer, lung cancer, gastric cancer, hepatocellular carcinoma, colorectal carcinoma, prostate cancer, cervical cancer, osteosarcoma, neuroblastoma, nasopharyngeal carcinoma. The aberrant expressions of SNHG1 have shown to contribute to proliferation, migration, and invasion of cancer cells.

CONCLUSIONS

SNHG1 represents promising novel biomarkers for various cancer types and have a great potential to be effectively used in clinical practice in the near future.

MicroRNAs, long noncoding RNAs, and circular RNAs: potential tumor biomarkers and targets for colorectal cancer

Noncoding RNAs (ncRNAs) can be divided into microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), pRNAs, and tRNAs. Traditionally, miRNAs exert their biological function mainly through the inhibition of translation via the induction of target RNA transcript degradation. lncRNAs and circRNAs were once considered to have no potential to code proteins. Here, we will review the current knowledge on ncRNAs in relation to their origins, characteristics, and functions. We will also review how ncRNAs work as competitive endogenous RNA, gene transcription and expression regulators, and RNA-binding protein sponges in colorectal cancer (CRC). Notably, except for the abovementioned mechanisms, recent advances revealed that lncRNAs can also act as the precursor of miRNAs, and a small portion of lncRNAs and circRNAs was verified to have the potential to code proteins, providing new evidence for the significance of ncRNAs in CRC tumorigenesis and development.

The lncRNA ZEB1-AS1 sponges miR-181a-5p to promote colorectal cancer cell proliferation by regulating Wnt/β-catenin signaling

Long noncoding RNAs (lncRNAs) are important regulators of the biological functions and underlying molecular mechanisms of colorectal cancer (CRC). However, the role of the lncRNA ZEB1-AS1 in CRC is not thoroughly understood. In this study, we found that ZEB1-AS1 was markedly upregulated in CRC. ZEB1-AS1 knockdown significantly suppressed CRC cell proliferation and induced apoptosis, whereas enhanced expression of ZEB1-AS1 had the opposite effect. Bioinformatics analysis identified miR-181a-5p as a candidate target of ZEB1-AS1. Moreover, we found an inverse correlation between ZEB1-AS1 and miR-181a-5p expression in CRC tissue. Inhibition of miR-181a-5p significantly upregulated ZEB1-AS1, whereas overexpression of miR-181a-5p had the opposite effect, suggesting that ZEB1-AS1 is negatively regulated by miR-181a-5p. Using luciferase reporter and RIP assays, we found that miR-181a-5p directly targets ZEB1-AS1. Importantly, ZEB1-AS1 may act as an endogenous 'sponge' to regulate miRNA targets by competing for miR-181a-5p binding. In summary, our findings provide the evidence supporting the role of ZEB1-AS1 as an oncogene in CRC. Our study also demonstrates that miR-181a-5p targets not only protein-coding genes but also the lncRNA ZEB1-AS1.

LncRNA HOXA-AS2 and its molecular mechanisms in human cancer

Long non-coding RNAs (lncRNAs), a novel class of noncoding RNAs, are commonly defined as RNA molecules more than 200 nucleotides in length. Emerging research indicated that lncRNA played a vital role in human tumorigenesis and progression by serving as tumor oncogenes or suppressors. LncRNA has been shown to get involved in participate various biological processes, such as cell growth, anti-apoptosis, migration and invasion. LncRNA HOXA cluster antisense RNA2 (HOXA-AS2) is a novel cancer-related lncRNA. It was recently found to exhibit aberrant expression in a variety of malignancies, including breast cancer, gastric cancer, gallbladder carcinoma, hepatocellular carcinoma and pancreatic cancer. The oncogenicity of lncRNA HOXA-AS2 mainly inhibits or promotes the expression of related genes through direct or indirect pathways, suggesting that HOXA-AS2 likely represents a feasible biomarker or therapeutic target in human cancers. In this review, we summarize current evidences concerning the biological functions and mechanisms of HOXA-AS2 during tumor development.

Colorectal neoplasia differentially expressed: a long noncoding RNA with an imperative role in cancer

Colorectal neoplasia differentially expressed (CRNDE), as a long noncoding RNA (lncRNA), has attracted increasing attention in recent years and has been documented to be at abnormally high expression in various types of cancer, such as colorectal cancer, glioma, hepatocellular carcinoma, lung cancer, and breast cancer. It could not only be used as a clinical biomarker for the early diagnosis and prognosis evaluation in a variety of cancers but also promote the development and progress of various tumor cells. Moreover, it is involved in the targeting regulation of multiple microRNAs and the activation/inhibition of multiple signaling pathways. In this review, we presented a systematic summary of the potential carcinogenicity and clinical value of CRNDE in the current evidence, so as to provide reference for early diagnosis, prognosis evaluation, and targeted therapy of various clinical cancers.