The long non-coding RNA H19-derived miR-675 modulates human gastric cancer cell proliferation by targeting tumor suppressor RUNX1

LncRNAs as potential diagnostic and prognostic biomarkers in gastric cancer: A novel approach to personalized medicine

Gastric cancer is the third leading cause of cancer death with 5-year survival rate of about 30-35%. Since early detection is associated with decreased mortality, identification of novel biomarkers for early diagnosis and proper management of patients with the best response to therapy is urgently needed. Long noncoding RNAs (lncRNAs) due to their high specificity, easy accessibility in a noninvasive manner, as well as their aberrant expression under different pathological and physiological conditions, have received a great attention as potential diagnostic, prognostic, or predictive biomarkers. They may also serve as targets for treating gastric cancer. In this review, we highlighted the role of lncRNAs as tumor suppressors or oncogenes that make them potential biomarkers for the diagnosis and prognosis of gastric cancer. Relatively, lncRNAs such as H19, HOTAIR, UCA1, PVT1, tissue differentiation-inducing nonprotein coding, and LINC00152 could be potential diagnostic and prognostic markers in patients with gastric cancer. Also, the impact of lncRNAs such as ecCEBPA, MLK7-AS1, TUG1, HOXA11-AS, GAPLINC, LEIGC, multidrug resistance-related and upregulated lncRNA, PVT1 on gastric cancer epigenetic and drug resistance as well as their potential as therapeutic targets for personalized medicine was discussed.

Roles of lncRNAs and circRNAs in regulating skeletal muscle development

The multistep biological process of myogenesis is regulated by a variety of myoblast regulators, such as myogenic differentiation antigen, myogenin, myogenic regulatory factor, myocyte enhancer factor2A-D and myosin heavy chain. Proliferation and differentiation during skeletal muscle myogenesis contribute to the physiological function of muscles. Certain non-coding RNAs, including long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), are involved in the regulation of muscle development, and the aberrant expressions of lncRNAs and circRNAs are associated with muscular diseases. In this review, we summarize the recent advances concerning the roles of lncRNAs and circRNAs in regulating the developmental aspects of myogenesis. These findings have remarkably broadened our understanding of the gene regulation mechanisms governing muscle proliferation and differentiation, which makes it more feasible to design novel preventive, diagnostic and therapeutic strategies for muscle disorders.

LINC00319 promotes migration, invasion and epithelial-mesenchymal transition process in cervical cancer by regulating miR-3127-5p/RPP25 axis

Cervical cancer is among the most prevalent malignancies for women. An increasing number of evidences have been proved that long non-coding RNAs (lncRNAs) play significant role in the initiation and progression of cervical cancer. However, the function of long intergenic non-protein coding RNA 319 (LINC00319) in cervical cancer still remains vague. In this study, our purpose was to investigate the effects of LINC00319 on cell migration, invasion and epithelial-mesenchymal transition (EMT) process in cervical cancer. It confirmed that LINC00319 was highly expressed in tissues and cell lines in cervical cancer. Further, overexpression of LINC00319 accelerates cell migration, invasion and EMT in cervical cancer. Moreover, LINC00319 could bind with miR-3127-5p and negatively regulated its expression. Besides, RPP25 was targeted by miR-3127-5p, and its expression was negatively/positively regulated by miR-3127-5p/LINC00319. Additionally, miR-3127-5p mimics or RPP25 insufficiency could offset the encouraging effects of LINC00319 overexpression on migration, invasion and EMT process in cervical cancer. Generally speaking, LINC00319 promotes migration, invasion and EMT process in cervical cancer by regulating miR-3127-5p/RPP25 axis, which may be conductive to cervical cancer treatment.

Long non-coding RNA signature in gastric cancer

Gastric cancer as a common human malignancy has been associated with aberrant expressions of several coding and non-coding genes. Long non-coding RNAs (lncRNAs) as regulators of gene expressions at different genomic, transcriptomic and post-transcriptomic levels are among putative biomarkers and therapeutic targets in gastric cancer. In the present study, we have searched available literature and listed lncRNAs that are involved in the pathogenesis of gastric cancer. In addition, we discuss associations between expressions of these lncRNAs and tumoral features or risk factors for gastric cancer. Based on the established role of lncRNAs in regulation of genomic stability, cell cycle, apoptosis, angiogenesis and other aspects of cell physiology, the potential of these transcripts as therapeutic targets in gastric cancer should be evaluated in future studies.

Identification of differentially expressed lncRNAs and mRNAs in luminal-B breast cancer by RNA-sequencing

BACKGROUND

Luminal B cancers show much worse outcomes compared to luminal A. This present study aims to screen key lncRNAs and mRNAs correlated with luminal-B breast cancer.

METHODS

Luminal-B breast cancer tissue samples and adjacent tissue samples were obtained from 4 patients with luminal-B breast cancer. To obtain differentially expressed mRNAs (DEmRNAs) and lncRNAs (DElncRNAs) between luminal-B breast cancer tumor tissues and adjacent tissues, RNA-sequencing and bioinformatics analysis were performed. Functional annotation of DEmRNAs and protein-protein interaction networks (PPI) construction were performed. DEmRNAs transcribed within a 100 kb window up- or down-stream of DElncRNAs were searched, which were defined as cis nearby-targeted DEmRNAs of DElncRNAs. DElncRNA-DEmRNA co-expression networks were performed. The mRNA and lncRNA expression profiles were downloaded from The Cancer Genome Atlas (TCGA) database to validate the expression patterns of selected DEmRNAs and DElncRNAs.

RESULTS

A total of 1178 DEmRNAs and 273 DElncRNAs between luminal-B breast cancer tumor tissues and adjacent tissues were obtained. Hematopoietic cell lineage, Cytokine-cytokine receptor interaction, Cell adhesion molecules (CAMs) and Primary immunodeficiency were significantly enriched KEGG pathways in luminal-B breast cancer. FN1, EGFR, JAK3, TUBB3 and PTPRC were five hub proteins of the PPI networks. A total of 99 DElncRNAs-nearby-targeted DEmRNA pairs and 1878 DElncRNA-DEmRNA co-expression pairs were obtained. Gene expression results validated in TCGA database were consistent with our RNA-sequencing results, generally.

CONCLUSION

This study determined key genes and lncRNAs involved in luminal-B breast cancer, which expected to present a new avenue for the diagnosis and treatment of luminal-B breast cancer.

High Expression of Long Noncoding RNA HOTAIRM1 is Associated with the Proliferation and Migration in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an incurable malignancy. Long noncoding RNA (LncRNA) HOTAIRM1 (HOX antisense intergenic RNA myeloid 1) has been shown to play important roles in the progression of several type cancers. However, the exact role of HOTAIRM1 in PDAC development remains largely unknown. This study aims to evaluate the potential function of HOTAIRM1 in the development and progress of PDAC. HOTAIRM1 expression was measured by RT-qPCR in forty seven paired human PDAC tissues and five PDAC cell lines. SW1990 and PANC-1 cells were transfected with siHOTAIRM1 to achieve HOTAIRM1 silence. MTT assay and colony formation assay were used to detect the effect of HOTAIRM1 knockdown on cell proliferation. The impact of HOTAIRM1 silence on cell cycle and apoptosis was assessed by flow cytometry assay. Transwell migration assay was performed to explore the influence of HOTAIRM1 downregulation on the migratory potential of PDAC cells. Western blot assay was applied to determine the expression changes of cell cycle, apoptosis, and migration-related genes before and after downregulating HOTAIRM1. HOTAIRM1 expression was abnormally upregulated in PDAC tissues and cells when compared with the control samples, and was positively associated with the expression of KRAS gene mutation. In vitro functional experiments, HOTAIRM1 expression was significantly downregulated by transfection with siHOTAIRM1 in SW1990 and PANC cell lines. HOTAIRM1 knockdown attenuated cell proliferation by inducing cell cycle arrest at G0/G1 phase, promoted cell apoptosis, and inhibited cell migration in PDAC cells by regulating related-genes expression. In conclusion, HOTAIRM1 plays a critical role in PDAC progression, which may be a novel diagnostic and rational therapeutic target for the treatment of pancreatic ductal adenocarcinoma.

RUNX1 promotes tumour metastasis by activating the Wnt/β-catenin signalling pathway and EMT in colorectal cancer

Background

Runt-related transcription factor 1 (RUNX1) plays the roles of an oncogene and an anti-oncogene in epithelial tumours, and abnormally elevated RUNX1 has been suggested to contribute to the carcinogenesis of colorectal cancer (CRC). However, the mechanism remains unclear.

Methods

The expression of RUNX1 in CRC and normal tissues was detected by real-time quantitative PCR and Western blotting. The effect of RUNX1 on CRC migration and invasion was conducted by functional experiments in vitro and in vivo. Chromatin Immunoprecipitation assay verified the direct regulation of RUNX1 on the promoter of the KIT, which leads to the activation of Wnt/β-catenin signaling.

Results

RUNX1 expression is upregulated in CRC tissues. Upregulated RUNX1 promotes cell metastasis and epithelial to mesenchymal transition (EMT) of CRC both in vitro and in vivo. Furthermore, RUNX1 can activate Wnt/β-catenin signalling in CRC cells by directly interacting with β-catenin and targeting the promoter and enhancer regions of KIT to promote KIT transcription. These observations demonstrate that RUNX1 upregulation is a common event in CRC specimens and is closely correlated with cancer metastasis and that RUNX1 promotes EMT of CRC cells by activating Wnt/β-catenin signalling. Moreover, RUNX1 is regulated by Wnt/β-catenin.

Conclusion

Our findings first demonstrate that RUNX1 promotes CRC metastasis by activating the Wnt/β-catenin signalling pathway and EMT.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1330-9) contains supplementary material, which is available to authorized users.

Akt in cancer: Mediator and more

Akt is a serine/threonine kinase and it participates in the key role of the PI3K signaling pathway. The Akt can be activated by a wide range of growth signals and the biochemical mechanisms leading to Akt activation are well defined. Once activated, Akt modulates the function of many downstream proteins involved in cellular survival, proliferation, migration, metabolism, and angiogenesis. The Akt is a central node of many signaling pathways and it is frequently deregulated in many types of human cancers. In this review, we provide an overview of Akt function and its role in the hallmarks of human cancer. We also discussed various mechanisms of Akt dysregulation in cancers, including epigenetic modifications like methylation, post-transcriptional non-coding RNAs-mediated regulation, and the overexpression and mutation.

Long non-coding RNAs are emerging targets of phytochemicals for cancer and other chronic diseases

The long non-coding RNAs (lncRNAs) are the crucial regulators of human chronic diseases. Therefore, approaches such as antisense oligonucleotides, RNAi technology, and small molecule inhibitors have been used for the therapeutic targeting of lncRNAs. During the last decade, phytochemicals and nutraceuticals have been explored for their potential against lncRNAs. The common lncRNAs known to be modulated by phytochemicals include ROR, PVT1, HOTAIR, MALAT1, H19, MEG3, PCAT29, PANDAR, NEAT1, and GAS5. The phytochemicals such as curcumin, resveratrol, sulforaphane, berberine, EGCG, and gambogic acid have been examined against lncRNAs. In some cases, formulation of phytochemicals has also been used. The disease models where phytochemicals have been demonstrated to modulate lncRNAs expression include cancer, rheumatoid arthritis, osteoarthritis, and nonalcoholic fatty liver disease. The regulation of lncRNAs by phytochemicals can affect multi-steps of tumor development. When administered in combination with the conventional drugs, phytochemicals can also produce synergistic effects on lncRNAs leading to the sensitization of cancer cells. Phytochemicals target lncRNAs either directly or indirectly by affecting a wide variety of upstream molecules. However, the potential of phytochemicals against lncRNAs has been demonstrated mostly by preclinical studies in cancer models. How the modulation of lncRNAs by phytochemicals produce therapeutic effects on cancer and other chronic diseases is discussed in this review.

Long non‑coding RNA H19 regulates cell growth and metastasis via the miR‑22‑3p/Snail1 axis in gastric cancer

Gastric cancer (GC) is the fifth most prevalent type of malignancy and the third leading cause of cancer‑related mortality worldwide, with the prognosis of patients with late‑stage GC remaining at poor levels. Long non‑coding RNA (lncRNA) H19 (H19) is involved in the growth and metastasis of tumors, and it is upregulated under hypoxic conditions and in certain types of cancer; however, the underlying mechanisms of action of this lncRNA as regards the initiation and development of GC remain unknown. Thus, in the present study, we aimed to determine the role of lncRNA H19 in GC and to elucidate the underlying mechanisms. H19 was found to be upregulated in GC tissues and cells compared with the para‑cancerous tissues, and an elevated expression of H19 was associated with lymph node metastasis and TNM stage. Furthermore, the downregulation of H19 suppressed the proliferation, invasion, migration and epithelial‑mesenchymal transition of GC cells in vitro and suppressed tumor growth in vivo. H19 was also found to be able to bind with miR‑22‑3p, and H19‑induced cell growth and metastasis were shown to be reversed by the upregulation of miR‑22‑3p; the miR‑22‑3p level was found to inversely correlate with H19 expression in GC tissues. Furthermore, the overexpression of miR‑22‑3p notably suppressed the proliferation, migration and invasion of GC cells, and these effects were enhanced by the downregulation of Snail1. In addition, cell growth and metastasis induced by miR‑22‑3p downregulation were partially reversed by the knockdown of Snail1. Furthermore, a negative correlation was observed between the mRNA expression levels of miR‑22‑3p and Snail1 in GC tissues. On the whole, the findings of the present study revealed that H19 was upregulated in GC tissues, which promoted tumor growth and metastasis via the miR‑22‑3p/Snail1 signaling pathway. In summary, these findings provide novel insight into the potential regulatory roles of H19 in GC, and suggest that the H19/miR‑22‑3p/Snail1 axis may prove to be a promising therapeutic target for the treatment of patients with GC.

Long Noncoding RNA MRPL39 Inhibits Gastric Cancer Proliferation and Progression by Directly Targeting miR-130

BACKGROUND

Gastric cancer (GC) is one of the most prevalent malignant tumors displaying both high incidence and mortality throughout much of the world. Recently, long noncoding RNAs (lncRNAs) have been implicated in the development and progression of GC.

MATERIALS AND METHODS

In the present study, we investigated the biological function and molecular mechanisms of lncRNA MRPL39 in GC.

RESULTS

We found that MRPL39 was significantly downregulated in GC tissues and cell lines and that its expression level was negatively associated with carcinoma size, tumor, lymph node, metastasis (TNM) stage, and lymphatic metastasis. Patients with low MRPL39 expression levels revealed a short overall and disease-free survival period. Over-expression of MRPL39 in the GC cell lines BGC823 and SGC-7901 inhibited cell growth, proliferation, migration, and invasion. MiR-130, a putative target gene of MRPL39, displayed an inverse association with the expression of MRPL39 in GC tissues and cell lines. Moreover, a luciferase assay demonstrated a direct binding between the miR-130 and MRPL39, and the reintroduction of miR-130 abrogated the anti-tumor effect of MRPL39 on GC cells.

CONCLUSION

Taken together, these findings indicate that MRPL39 serves as a tumor suppressor by directly targeting miR-130 in GC, which suggests that it might be a novel biomarker in the diagnosis and prognosis of GC.

Potential Role of lncRNA H19 as a Cancer Biomarker in Human Cancers Detection and Diagnosis: A Pooled Analysis Based on 1585 Subjects

Long noncoding RNAs (lncRNAs) have been reported to serve as diagnostic and prognostic biomarkers of cancers, which play vital roles in tumorigenesis and tumor progression. Several studies have been performed to explore diagnostic value of lncRNA H19 in cancer detection and diagnosis. However, there are still inconsistent results in diagnostic accuracy and reliability in individual studies. Therefore, the present study was performed to summarize the overall diagnostic performance of lncRNA H19 in cancer detection and diagnosis. A total of eight studies with 770 cases and 815 controls were included in this pooled analysis. The pooled diagnostic results were as follows: sensitivity, 0.69 (95%CI=0.62-0.76), specificity, 0.79 (95% CI=0.70-0.86), positive likelihood ratio (PLR), 3.31 (95%CI=2.29-4.78), negative likelihood (NLR), 0.39 (95%CI=0.31-0.49), diagnostic odds ratio (DOR), 8.53 (95%CI=4.99-14.60), and area under the curve (AUC), 0.79 (95%CI=0.76-0.83). Deeks' funnel plot asymmetry test (P=0.13) suggested no potential publication bias. Our results indicated that lncRNA H19 had a relatively moderate accuracy in cancer detection and diagnosis. Further comprehensive prospective studies with large sample sizes are urgently required to validate our findings.

LncRNA H19 interacted with miR-130a-3p and miR-17-5p to modify radio-resistance and chemo-sensitivity of cardiac carcinoma cells

The current investigation explored the synthetic contribution of lncRNA H19, miR-130a-3p, and miR-17-5p to radio-resistance and chemo-sensitivity of cardiac cancer cells. Totally 284 human cardiac cancer tissues were gathered, and they have been pathologically diagnosed. The cardiac cancer cells were isolated with utilization of the mechanic method. Moreover, cisplatin, adriamycin, mitomycin, and 5-fluorouracil were designated as the chemotherapies, and single-dose X-rays were managed as the radiotherapy for cardiac cancer cells. We also performed luciferase reporter gene assay to verify the targeted relationship between H19 and miR-130a-3p, as well as between H19 and miR-17-5p. Finally, mice models were established to examine the functions of H19, miR-130a-3p, and miR-17-5p on the development of cardiac cancer. The study results indicated that H19, miR-130a-3p, and miR-17-5p expressions within cardiac cancer tissues were significantly beyond those within adjacent nontumor tissues (P < 0.05), and H19 expression was positively correlated with both miR-130a-3p (r_s  = 0.43) and miR-17-5p (r_s  = 0.49) expressions. The half maximal inhibitory concentrations (IC50) of cisplatin, adriamycin, mitomycin, and 5-fluorouracil for cardiac cancer cells were, respectively, determined as 2.01 μg/mL, 8.35 μg/mL, 24.44 μg/mL, and 166.42 μg/mL. The overexpressed H19, miR-130a-3p, and miR-17-5p appeared to improve the survival rate and viability of cardiac cancer cells that were exposed to chemotherapies and X-rays (all P < 0.05). It was also drawn from luciferase reporter gene assay that H19 could directly target miR-130a-3p and miR-17-5p, thereby modifying the sensitivity of cardiac cancer cells to drugs and X-rays (P < 0.05). Finally, the mice models also produced larger tumor size and higher tumor weight, when H19, miR-130a-3p, or miR-17-5p expressions were up-regulated within them (P < 0.05). In conclusion, H19 could act on miR-130a-3p or miR-17-5p to alter the radio- and chemo-sensitivities of cardiac cancer cells, helping to improve the radio-/chemotherapies for cardiac cancer.

PCAT-1: A Novel Oncogenic Long Non-Coding RNA in Human Cancers

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides (nts) without obvious protein coding potential. lncRNAs act as multiple roles in biological processes of diseases, especially carcinomas. Prostate cancer associated transcript-1 (PCAT-1) is an oncogenic lncRNA that identified by RNA-Sequence in prostate cancer. High expression of PCAT-1 is observed in different types of cancers, including prostate cancer, colorectal cancer, hepatocellular cancer and gastric cancer. High expressed PCAT-1 is correlated with poor overall survival. Furthermore, PCAT-1 regulates cancer cell proliferation, apoptosis, migration and invasion. Additionally, PCAT-1 is involved in EMT and Wnt/β-catenin-signaling pathway. In this review, we focus on the implication of PCAT-1 in human cancers.

CircPSMC3 suppresses the proliferation and metastasis of gastric cancer by acting as a competitive endogenous RNA through sponging miR-296-5p

BACKGROUND

Circular RNAs (circRNAs) are a class of non-coding RNAs with a loop structure, but its functions remain largely unknown. Growing evidence has revealed that circRNAs play a striking role as functional RNAs in the progression of malignant disease. However, the precise role of circRNAs in gastric cancer (GC) remains unclear.

METHODS

CircRNAs were determined by human circRNA array analysis and quantitative reverse transcription polymerase reaction. Luciferase reporter, RNA pull down, and fluorescence in situ hybridization assays were employed to test the interaction between circPSMC3 and miR-296-5p. Ectopic over-expression and siRNA-mediated knockdown of circPSMC3, proliferation, migration and invasion in vitro, and in vivo experiment of metastasis were used to evaluate the function of circPSMC3.

RESULTS

CircPSMC3 rather than liner PSMC3 mRNA was down-regulated in GC tissues, corresponding plasmas from GC patients as well as GC cell lines compared to normal controls. Lower circPSMC3 expression in GC patients was correlated with higher TNM stage and shorter overall survival. Over-expression of circPSMC3 and miR-296-5p inhibitor could inhibit the tumorigenesis of gastric cancer cells in vivo and vitro whereas co-transfection of circPSMC3 and miRNA-296-5p could counteract this effect. Importantly, we demonstrated that circPSMC3 could act as a sponge of miR-296-5p to regulate the expression of Phosphatase and Tensin Homolog (PTEN), and further suppress the tumorigenesis of gastric cancer cells.

CONCLUSION

Our study reveals that circPSMC3 can serve as a novel potential circulating biomarker for detection of GC. CircPSMC3 participates in progression of gastric cancer by sponging miRNA-296-5p with PTEN, providing a new insight into the treatment of gastric cancer.

LncRNA‑NEF is involved the regulation of gastric carcinoma cell proliferation by targeting RUNX1

Neighboring enhancer of FOXA2 (NEF) is a newly discovered long non‑coding RNA (lncRNA) that serves an oncogenic function in the metastasis of hepatocellular carcinoma, while its involvement in other types of cancer and in tumor cell proliferation remain unknown. In the present study, tumor tissues and adjacent healthy tissues were obtained from patients with gastric carcinoma, and blood was extracted from patients with gastric carcinoma and healthy controls. Expression of NEF in those tissues was detected using a reverse transcription‑quantitative polymerase chain reaction. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic value of serum lncRNA NEF for gastric carcinoma. All patients were followed‑up for 5 years following discharge, and survival curves were plotted to evaluate the diagnostic value of serum lncRNA‑NEF for gastric carcinoma. LncRNA‑NEF overexpression and small interfering RNA (siRNA) silencing cell lines were established and the effects on cell proliferation and runt‑related transcription factor 1 (Runx1) expression were detected using a Cell Counting Kit‑8 assay and western blot analysis, respectively. It was revealed that NEF was significantly downregulated in tumor tissues compared with in adjacent tissues. Levels of circulation NEF in serum were lower in patients with gastric carcinoma compared with in healthy controls, and were decreased with the increasing stages of primary tumor. Serum NEF is a sensitive diagnostic and prognostic marker for gastric carcinoma. NEF siRNA silencing promoted, and overexpression inhibited, gastric carcinoma proliferation. In addition, NEF overexpression promoted, and NEF siRNA silencing inhibited, Runx1 expression. Therefore, it was concluded that lncRNA NEF may participate in the regulation of cancer cell proliferation by regulating Runx1 expression.

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.

LncRNA H19 promotes the proliferation of pulmonary artery smooth muscle cells through AT1R via sponging let-7b in monocrotaline-induced pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is related to inflammation, and the lncRNA H19 is associated with inflammation. However, whether PDGF-BB-H19-let-7b-AT1R axis contributes to the pathogenesis of PAH has not been thoroughly elucidated to date. This study investigated the role of H19 in PAH and its related mechanism.

METHODS

In the present study, SD rats, C57/BL6 mice and H19-/- mice were injected with monocrotaline (MCT) to establish a PAH model. H19 was detected in the cytokine-stimulated pulmonary arterial smooth muscle cells (PASMCs), serum and lungs of rats/mice. H19 overexpression and knockdown experiments were also conducted. A dual luciferase reporter assay was used to explore whether let-7b is a sponge miRNA of H19, and AT1R is a novel target of let-7b. A CCK-8 assay and flow cytometry were used to analyse cell proliferation.

RESULTS

The results showed that H19 was highly expressed in the serum and lungs of MCT-induced rats/mice, and H19 was upregulated by PDGF-BB in vitro. H19 upregulated AT1R expression via sponging miRNA let-7b following PDGF-BB stimulation. AT1R is a novel target of let-7b. Moreover, the overexpression of H19 and AT1R could facilitate PASMCs proliferation in vitro. H19 knockout protected mice from pulmonary artery remodeling and PAH following MCT treatment.

CONCLUSION

Our study showed that H19 is highly expressed in MCT-induced rodent lungs and upregulated by PDGF-BB. The H19-let-7b-AT1R axis contributed to the pathogenesis of PAH by stimulating PASMCs proliferation. The H19 knockout had a protective role in the development of PAH. H19 may be a potential tar-get for the treatment of PAH.

LONG-NONCODING RNAs in gastroesophageal cancers

Despite continuing improvements in multimodal therapies, gastro-esophageal malignances remain widely prevalent in the population and is characterized by poor overall and disease-free survival rates. Due to the lack of understanding about the pathogenesis and absence of reliable markers, gastro-esophageal cancers are associated with delayed diagnosis. The increasing understanding about cancer's molecular landscape in the recent years, offers the possibility of identifying 'targetable' molecular events and in particular facilitates novel treatment strategies and development of biomarkers for early stage diagnosis. At least 98% of our genome is actively transcribed into non-coding RNAs encompassing long non-coding RNAs (lncRNAs) constituted of transcripts longer than 200 nucleotides with no protein-coding capacity. Many studies have demonstrated that lncRNAs are functional genomic elements playing pivotal roles in main oncogenic processes. LncRNA can act at multiple levels developing a complex molecular network that can modulate directly or indirectly the expression of genes involved in tumorigenesis. In this review, we focus on lncRNAs as emerging players in gastro-esophageal carcinogenesis and critically assess their potential as reliable noninvasive biomarkers and in next generation targeted therapies.

miR675 Accelerates Malignant Transformation of Mesenchymal Stem Cells by Blocking DNA Mismatch Repair

miR675 is highly expressed in several human tumor tissues and positively regulates cell progression. Herein, we demonstrate that miR675 promotes malignant transformation of human mesenchymal stem cells. Mechanistically, we reveal that miR675 enhances the expression of the polyubiquitin-binding protein p62. Intriguingly, P62 competes with SETD2 to bind histone H3 and then significantly reduces SETD2-binding capacity to substrate histone H3, triggering drastically the reduction of three methylation on histone H3 36th lysine (H3K36me3). Thereby, the H3K36me3-hMSH6-SKP2 triplex complex is significantly decreased. Notably, the ternary complex’s occupancy capacity on chromosome is absolutely reduced, preventing it from DNA damage repair. By virtue of the reductive degradation ability of SKP2 for aging histone H3.3 bound to mismatch DNA, the aging histone H3.3 repair is delayed. Therefore, the mismatch DNA escapes from repair, triggering the abnormal expression of several cell cycle-related genes and causing the malignant transformation of mesenchymal stem cells. These observations strongly suggest understanding the novel functions of miR675 will help in the development of novel therapeutic approaches in a broad range of cancer types.

Co-expression profiling of plasma miRNAs and long noncoding RNAs in gastric cancer patients

PURPOSE

The recent researches indicate that differential non-coding RNAs expression signatures could be associated with the pathogenesis of gastric cancer (GC). However, there are few studies focused on lncRNA-miRNAs co-expression profiling in GC patients. Therefore, in the present study the expression of H19 and MEG3 and their related miRNAs including miR-148a-3p, miR-181a-5p, miR-675-5p and miR-141-3p were determined in the plasma samples of GC patients and controls.

MATERIALS AND METHODS

This case-control study included 62 GC patients and 40 age- sex matched controls. The non-coding RNA levels were assessed by real-time PCR. Further, using in silico analysis, we identified shared targets of studied miRNAs and performed GC-associated pathway enrichment analysis.

RESULTS

Our results showed that the H19 level was significantly (P = 0.008) elevated and MEG3 expression was significantly (P = 0.002) down-regulated in GC patients compared to healthy participants. Furthermore, it was revealed that the miR-675-5p level was increased, while miR-141-3p plasma levels were significantly reduced in GC patients (P < 0.05). We did not observe a significant difference for miR-148a-3p (P = 0.682) and miR-181a-5p (P = 0.098) expression between groups. In addition, the expression levels of H19, MEG3 and miR-148a-3p were associated with some clinicopathological features of patients (P < 0.05). ROC analysis revealed that a combination of H19, MEG3 and miR-675-5p levels able to discriminate controls and GC subjects with 88.87% sensitivity and 85% specificity (AUC, 0.927; 0.85-0.96 CI, P < 0.0001).

CONCLUSION

The results of current study demonstrated that combination of H19, MEG3 and miR-675-5p expression levels could provide a potential diagnostic panel for GC.

Identification of plasma RGS18 and PPBP mRNAs as potential biomarkers for gastric cancer using transcriptome arrays

Coding and noncoding RNAs serve a crucial role in tumorigenesis. Circulating RNAs have been recognized as a novel category of biomarkers for a variety of physiological and pathological conditions. To identify plasma RNA biomarkers for gastric cancer (GC), a genome-wide transcriptome analysis using GeneChip^® Human Transcriptome Array, which contains probe sets covering exons of ~67500 coding and noncoding transcripts of annotated genes, was performed to screen for the RNAs that exhibited differential expression in the plasma samples of patients with GC and controls. The expression levels of 6 candidate RNAs, including regulator of G-protein signaling 18 (RGS18), integral membrane protein 2B, pro-platelet basic protein (PPBP), nucleosome assembly protein1-like 1, n324674 and ENST00000442382 were assessed in the plasma samples of 81 patients with GC and 77 healthy participants using reverse transcription-quantitative polymerase chain reaction. Furthermore, the expression levels of RGS18 and PPBP mRNAs were indicated to be significantly differentially expressed (P<0.0001) in an independent panel of plasma samples of 36 patients with GC compared with 34 healthy participants. The potential association of RGS18 and PPBP mRNA expression levels with clinicopathological features was subsequently analyzed. Receiver operating characteristic analysis indicated that the combination of these 2 mRNAs with an area under curve <0.812 was an improved indicator for gastric cancer compared with respective individual levels. The results of the present study indicate that RGS18 and PPBP mRNA expression was significantly downregulated in the plasma of patients with GC, and the combination of these 2 mRNAs may be a useful diagnostic or prognostic marker for GC.

MicroRNA 675 cooperates PKM2 to aggravate progression of human liver cancer stem cells induced from embryonic stem cells

Both miR675 and pyruvate kinase M2 (PKM2) contribute to malignant progression of tumor, but its functions in liver cancer stem cells remain unclear. Herein, our findings indicate that miR675 plus PKM2 strongly promotes the growth of liver cancer stem cells. Mechanistically, miR675 plus PKM2 enhances the transcriptional activity of SUV39h2. On the other hand, the excessive SUV39h2 binds to more substrate histone H3, triggering an increase of tri-methylation of histone H3 on the ninth lysine. Furthermore, the tri-methylation of histone 3 on the ninth lysine (H3K9me3)-heterochromatin protein 1 alpha (HP1α) complex is increased when the complex occupancy ability on the C-myc promoter region is raised, recruiting CREB, P300, and RNApolII to the special position that results in C-myc high abundance. Therefore, miR675 plus PKM2 triggered the upregulation of C-myc by increasing the interaction between H3K9me3 and HP1α. Understanding the signaling pathways that miR675 plus PKM2 epigenetically possesses during the malignant transformation of liver cancer stem cells will contribute to more effective liver cancer therapies.

Long non-coding RNA AB007962 is downregulated in gastric cancer and associated with poor prognosis

A number of previous studies have reported that numerous long non-coding RNAs (lncRNAs) are dysregulated in gastric cancer (GC) and are involved in a series of biological and pathological processes. Total RNA was extracted from the cancerous tissues and matched normal adjacent tissues (NATs) of 96 patients with GC. The expression level of AB007962, a novel lncRNA, was determined by reverse transcription-quantitative polymerase chain reaction. The association between AB007962 expression levels and clinicopathological features were analyzed. Kaplan-Meier curves were also constructed in order to evaluate prognosis. Finally, publicly accessible data from The Cancer Genome Atlas was used to further verify the expression levels and clinical significance of AB007962. In conclusion, it was determined that the expression level of AB007962 was significantly reduced, compared with matched NATs in GC tissues (P=0.003). Survival analysis indicated that patients with intestinal-type GC with a reduced expression of AB007962 had a reduced prognosis, compared with those with an increased expression. AB007962 may be involved in the progression of GC and act as a novel prognostic biomarker for patients with GC, particularly in intestinal-type GC.

Long Non-Coding RNAs in Obesity-Induced Cancer

Many mechanisms of obesity-induced cancers have been proposed. However, it remains unclear whether or not long non-coding RNAs (lncRNAs) play any role in obesity-induced cancers. In this article, we briefly discuss the generally accepted hypotheses explaining the mechanisms of obesity-induced cancers, summarize the latest evidence for the expression of a number of well-known cancer-associated lncRNAs in obese subjects, and propose the potential contribution of lncRNAs to obesity-induced cancers. We hope this review can serve as an inspiration to scientists to further explore the regulatory roles of lncRNAs in the development of obesity-induced cancers. Those findings will be fundamental in the development of effective therapeutics or interventions to combat this life-threatening adverse effect of obesity.

Identification of molecular biomarkers for the diagnosis of gastric cancer and lymph-node metastasis

Background and objective

Biomarkers are important tools for prompt diagnosis of cancer. This study aimed to identify reliable biomarkers for clinical applications in the diagnosis of gastric cancer and lymph-node (LN) metastasis.

Methods

Between 1 December 2014 and 31 December 2015, we prospectively collected samples of gastric-cancer tissues, corresponding matched-pair normal gastric mucosa, and their peri-gastric metastatic and non-metastatic LNs to identify quantitatively reliable genes using quantitative real-time polymerase chain reaction. Relative quantity (RQ) was used to calculate the mRNA expression levels of our target genes. Statistics were calculated using one-way analysis of variance (ANOVA) and Tukey’s multiple comparison test. Analytical graphs were plotted using GraphPad Prism.

Results

Of nine assessed genes, the mRNA levels of inhibin beta A (INHBA) and secreted phosphoprotein 1 (SPP1) were most consistently highly expressed in tumor tissues by 15.4- and 15.6-fold, respectively, as compared with normal tissues (P < 0.001), with 91.3% sensitivity and 95.7% specificity (receiver operating characteristic [ROC] curve area = 0.974) for the former and 82.6% sensitivity and 87.0% specificity (ROC curve area = 0.924) for the latter. Further analysis revealed no differentiating significance of SPP1 mRNA expression between metastatic and non-metastatic LNs (P = 0.470). In contrast, the INHBA mRNA level was up-regulated 4.1-fold in metastatic LNs (P < 0.001), with 80.0% sensitivity and 81.5% specificity (ROC curve area = 0.857), and was also able to successfully differentiate between more severe disease conditions, T3 and T4 (P = 0.003), M0 and M1 (P = 0.043) and different histological variants (intestinal type vs diffuse type, P = 0.019).

Conclusions

Our results showed that INHBA was the most optimally reliable biomarker for diagnosing gastric cancer and LN metastasis.

A long noncoding RNA MAP3K1-2 promotes proliferation and invasion in gastric cancer

Background

Long noncoding RNAs (lncRNAs) have been implicated in several human cancers. The expression profile and underlying mechanism of the lncRNA MAP3K1-2 in gastric cancer (GC) are poorly understood.

Methods

Sixty-one patients with GC were recruited from Shanghai Baoshan Luo Dian Hospital (Shanghai, China). Tumor tissues and paired normal tissues (5 cm adjacent to the tumor) were obtained. Expression of lncRNA MAP3K1-2 in GC cell lines was examined using quantitative real-time polymerase chain reaction. Protein expression was detected using Western blot. Cell cycle analysis was assessed using flow cytometry. Cell proliferation was assessed using soft agar assays, and cell invasion was assessed using Transwell assays.

Results

The expression level of lncRNA MAP3K1-2 was upregulated in GC cells and markedly higher in poorly differentiated cell lines. Silencing treatment of lncRNA MAP3K1-2 significantly inhibited cell proliferation and invasion in GC. In addition, knockdown of lncRNA MAP3K1-2 significantly inhibited the function of important genes in the MAPK signaling pathway. Higher expression of lncRNA MAP3K1-2 was often associated with poorer prognosis in patients with GC.

Conclusions

lncRNA MAP3K1-2 is a critical effector in GC tumorigenesis and progression, representing novel therapeutic targets. High lncRNA MAP3K1-2 expression may serve as a novel independent prognostic marker for predicting the outcome of GC.

Overexpression of MAPT-AS1 is associated with better patient survival in breast cancer

Breast cancer is the most frequent malignant disease in women worldwide. It is a heterogeneous and complex genetic disease with different molecular characteristics. MAPT-AS1, a long non-coding RNA (lncRNA) existing at the anti-sense strand of the MAPT (microtubule associated protein tau) promoter region, was believed to regulate MAPT, which was associated with disease state in Parkinson's disease. But the role of MAPT-AS1 in breast cancer has never been reported. In our study we found that MAPT-AS1 is overexpressed in breast cancer but not in triple negative breast cancer (TNBC), and that high expression of MAPT-AS1 was correlated with better patient survival. In addition, the level of MAPT-AS1 was correlated with the expression of MAPT, and MAPT was associated with survival time in breast cancer. Our study suggests that MAPT-AS1 may play a role and be a potential survival predictive biomarker in breast cancer.

Circulating long non-coding RNAs HULC and ZNFX1-AS1 are potential biomarkers in patients with gastric cancer

Long non-coding RNAs (lncRNAs) have been demonstrated to be involved in different types of cancer, including gastric cancer. Although altered lncRNAs profiles have been observed in or around gastric cancer tissues, the diagnostic value of circulating lncRNAs in gastric cancer remains unclear. In the present study, a number of highly expressed lncRNAs, including uc001lsz, GACAT2, ABHD11-AS1, GACAT3, SUMP1P3, CHET1, TUG1, SNHG12, GAS5, PVT1, LINC00152, HOTAIR, CCAT1, H19, HULC and ZNFX1-AS1, were investigated as potential minimally invasive biomarkers for this tumor. Preliminary screening experiments revealed that ZNFX1-AS1 and HULC were differentially expressed in the plasma of gastric cancer patients and healthy control subjects. The study further examined the relative expression of ZNFX1-AS1 and HULC in the plasma of 50 matching preoperative and postoperative patients, 50 gastrointestinal stromal tumor (GIST) patients, 50 gastritis/peptic ulcer patients and 50 healthy control subjects through reverse transcription-quantitative polymerase chain reaction. The correlation of lncRNA relative expression with the general characteristics and clinicopathological factors was analyzed. It was observed that the levels of ZNFX1-AS1 and HULC in the plasma of preoperative patients were markedly higher compared with those in the plasma of GIST patients, gastritis/peptic ulcer patients and healthy control subjects, while no significant difference was detected among these three groups. Receiver operating characteristic curve analysis was also conducted to distinguish gastric cancer patients from healthy control subjects. The area under the curve was 0.85 and 0.65 for ZNFX1-AS1 and HULC, respectively. In conclusion, the results indicated that the lncRNAs ZNFX1-AS1 and HULC are promising in the clinical diagnosis of gastric cancer.

H19 contributes to poor clinical features in NSCLC patients and leads to enhanced invasion in A549 cells through regulating miRNA-203-mediated epithelial-mesenchymal transition

Recent studies have demonstrated that the overexpression of H19 may contribute towards development of tumorigenesis in various types of cancer. To investigate the role of H19 in the development of non-small cell lung cancer (NSCLC), 76 NSCLC tissues samples and their adjacent normal tissue samples were collected. Expression level of H19, and its association with clinicopathological features and overall survival was analyzed. It was found that compared with normal adjacent tissues, H19 expression was elevated in NSCLC tissues along with a decreased miR-203 expression level. It was also found that patients who were in advanced clinical stages had a higher H19 and a lower miR-203 expression compared to normal tissues. The overall survival time of patients with higher H19 expression was shorter compared with the lower H19 expression group. Upregulation of A549 enhanced cell proliferation and promoted invasion. Overexpression of H19 stimulated the epithelial-mesenchymal transition (EMT) process in lung cancer cells and demonstrated typical morphological characteristics of EMT. The level of mesenchymal marker protein, such as Vimentin and SNAI1 increased; while CDH1 protein level decreased. Also, H19 negatively regulated miR-203. Inhibition of H19 attenuated miR-203 induced EMT process. Upregulation of H19 contributes to poor clinical features in patients with NSCLC, induces occurrence of EMT, promotes proliferation and stimulates cell invasion in NSCLC cell line through regulating miRNA-203 mediated EMT.

Long non-coding RNA-mediated regulation of signaling pathways in gastric cancer

Gastric cancer (GC) is one of the most common cancers globally. Because of the high frequency of tumor recurrence, or metastasis, after surgical resection, the prognosis of patients with GC is poor. Therefore, exploring the mechanisms underlying GC is of great importance. Recently, accumulating evidence has begun to show that dysregulated long non-coding RNAs (lncRNAs) participate in the progression of GC via several typical signaling pathways, such as the AKT and MAPK signaling pathways. Moreover, the interactions between lncRNAs and microRNAs appear to represent a novel mechanism in the pathogenesis of GC. This review provides a synopsis of the latest research relating to lncRNAs and associated signaling pathways in GC.

Long non-coding RNA H19 contributes to apoptosis of hippocampal neurons by inhibiting let-7b in a rat model of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is one of the most common types of intractable epilepsy, characterized by hippocampal neuron damage and hippocampal sclerosis. Long noncoding RNAs (lncRNAs) have been increasingly recognized as posttranscriptional regulators. However, their expression levels and functions in TLE remain largely unknown. In the present study, TLE rat model is used to explore the expression profiles of lncRNAs in the hippocampus of epileptic rats using microarray analysis. Our results demonstrate that H19 is the most pronouncedly differentiated lncRNA, significantly upregulated in the latent period of TLE. Moreover, the in vivo studies using gain- and loss-of-function approaches reveal that the overexpression of H19 aggravates SE-induced neuron apoptosis in the hippocampus, while inhibition of H19 protects the rats from SE-induced cellular injury. Finally, we show that H19 might function as a competing endogenous RNA to sponge microRNA let-7b in the regulation of cellular apoptosis. Overall, our study reveals a novel lncRNA H19-mediated mechanism in seizure-induced neural damage and provides a new target in developing lncRNA-based strategies to reduce seizure-induced brain injury.

New insights of Helicobacter pylori host-pathogen interactions: The triangle of virulence factors, epigenetic modifications and non-coding RNAs

Helicobacter pylori (H. pylori) is a model organism for understanding host-pathogen interactions and infection-mediated carcinogenesis. Gastric cancer and H. pylori colonization indicates the strong correlation. The progression and exacerbation of H. pylori infection are influenced by some factors of pathogen and host. Several virulence factors involved in the proper adherence and attenuation of immune defense to contribute the risk of emerging gastric cancer, therefore analysis of them is very important. H. pylori also modulates inflammatory and autophagy process to intensify its pathogenicity. From the host regard, different genetic factors particularly affect the development of gastric cancer. Indeed, epigenetic modifications, MicroRNA and long non-coding RNA received more attention. Generally, various factors related to pathogen and host that modulate gastric cancer development in response to H. pylori need more attention due to develop an efficacious therapeutic intervention. Therefore, this paper will present a brief overview of host-pathogen interaction especially emphases on bacterial virulence factors, interruption of host cellular signaling, the role of epigenetic modifications and non-coding RNAs.

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.

Regulatory network analysis of high expressed long non-coding RNA LINC00941 in gastric cancer

Accumulating evidence suggests that the aberrant expression of long non-coding RNAs is closely related to the carcinogenesis and progression of gastric cancer (GC), which is a type of prevalent tumor with a high incidence and mortality rate. However, it is still a challenge to find reliable biomarkers and to understand their molecular mechanisms in GC. In this study, we first confirmed that LINC00941was up-regulated in GC tumor tissues compared with adjacent normal tissues by RT-PCR, and found that the expression level of LINC00941 was correlated with invasion depth, lymphatic metastasis, and the TNM stage of patients with GC. Furthermore, by performing enrichment analysis based on the co-expression network and regulatory network, we found that LINC00941 was associated with cancer related biological processes such as cell cycle, cell communication, cell migration, cell division, as well as processes associated with the immune system. Our results suggested that LINC00941 may be a potential novel biomarker for therapeutic or diagnostic of GC.

In silico identification of microRNAs predicted to regulate N-myristoyltransferase and Methionine Aminopeptidase 2 functions in cancer and infectious diseases

Protein myristoylation is a key protein modification carried out by N-Myristoyltransferase (NMT) after Methionine aminopeptidase 2 (MetAP2) removes methionine from the amino-terminus of the target protein. Protein myristoylation by NMT augments several signaling pathways involved in a myriad of cellular processes, including developmental pathways and pathways that when dysregulated lead to cancer or immune dysfunction. The emerging evidence pointing to NMT-mediated myristoylation as a major cellular regulator underscores the importance of understanding the framework of this type of signaling event. Various studies have investigated the role that myristoylation plays in signaling dysfunction by examining differential gene or protein expression between normal and diseased states, such as cancers or following HIV-1 infection, however no study exists that addresses the role of microRNAs (miRNAs) in the regulation of myristoylation. By performing a large scale bioinformatics and functional analysis of the miRNAs that target key genes involved in myristoylation (NMT1, NMT2, MetAP2), we have narrowed down a list of promising candidates for further analysis. Our condensed panel of miRNAs identifies 35 miRNAs linked to cancer, 21 miRNAs linked to developmental and immune signaling pathways, and 14 miRNAs linked to infectious disease (primarily HIV). The miRNAs panel that was analyzed revealed several NMT-targeting mRNAs (messenger RNA) that are implicated in diseases associated with NMT signaling alteration, providing a link between the realms of miRNA and myristoylation signaling. These findings verify miRNA as an additional facet of myristoylation signaling that must be considered to gain a full perspective. This study provides the groundwork for future studies concerning NMT-transcript-binding miRNAs, and will potentially lead to the development of new diagnostic/prognostic biomarkers and therapeutic targets for several important diseases.

Long noncoding RNAs in gastric cancer carcinogenesis and metastasis

Recent studies of the human transcriptome, most prominently by the ENCyclopedia Of DNA Elements project, have revealed an unexpected number of noncoding RNAs (ncRNAs). Long noncoding RNAs (lncRNAs) are typically referred to a heterogeneous group of polyadenylated long ncRNAs, with a length of > 200 nt. LncRNAs constitute an integral part of tumor biology, with many lncRNAs discovered to be aberrantly expressed in various cancer types. They are involved in many aspects of cancer pathogenesis from its initiation to progression, metastasis and treatment response. Gastric cancer (GC) is the third leading cause of cancer death worldwide. Despite the current improvements of life expectancy and survival rate, most of the patients are diagnosed when their cancer has been progressed to advanced stages. Therefore, unraveling the molecular mechanisms of GC to find early-stage biomarkers is urgent. As the list of lncRNAs with deregulated expression in GC is steadily expanding, these molecules offer a source for developing GC-specific biomarkers. In this review, we will present and discuss those lncRNAs whose expression has been shown to be deregulated in GC.

The lncRNA H19 positively affects the tumorigenic properties of glioblastoma cells and contributes to NKD1 repression through the recruitment of EZH2 on its promoter

The still largely obscure molecular events in the glioblastoma oncogenesis, a primary brain tumor characterized by an inevitably dismal prognosis, impel for investigation. The importance of Long noncoding RNAs as regulators of gene expression has recently become evident. Among them, H19 has a recognized oncogenic role in several types of human tumors and was shown to correlate to some oncogenic aspects of glioblastoma cells. Here we, hypothesyze that in glioblastoma H19 exerts its function through the interaction with the catalytic subunit of the PRC2 complex, EZH2. By employing a factor analysis on a SAGE dataset of 12 glioblastoma samples, we show that H19 expression in glioblastoma tissues correlates with that of several genes involved in glioblastoma growth and progression. H19 knock-down reduces viability, migration and invasiveness of two distinct human glioblastoma cell lines. Most importantly, we provide a mechanistic perspective about the role of H19 in glioblastoma cells, by showing that its expression is inversely linked to that of NKD1, a negative regulator of Wnt pathway, suggesting that H19 might regulate NKD1 transcription via EZH2-induced H3K27 trimethylation of its promoter. Indeed, we showed that H19 binds EZH2 in glioblastoma cells, and that EZH2 binding to NKD1 and other promoters is impaired by H19 silencing.

In this work we describe H19 as part of an epigenetic modulation program executed by EZH2, that results in the repression of Nkd1. We believe that our results can provide a new piece to the complex puzzle of H19 function in glioblastoma.

Association of lncRNA H19 rs217727 polymorphism and cancer risk in the Chinese population: a meta-analysis

Reports on the relationship between the lncRNA H19 rs217727 polymorphism and the risk of cancer in the Chinese population have been inconsistent. Therefore, we performed a meta-analysis to evaluate this association, by searching the Embase, PubMed, Web of Science, Wanfang, and CNKI databases. Four case-control studies with 3,157 cases and 3,564 controls were selected for this meta-analysis. The odds ratios with 95% confidence intervals were examined using the random effect model. Allelic (A vs. G), dominant (AA + GA vs. GG), recessive (AA vs. GA + GG), and additive (AA vs. GG) genetic models were used to determine the association. Overall, no significant association was observed between the rs217727 polymorphism and cancer susceptibility in any of the four genetic models. Sensitivity analysis revealed that the results were stable in the allelic and dominant genetic models, but those from the recessive and additive models were unstable, which should be treated with caution. Our meta-analysis suggests that the lncRNA H19 rs217727 polymorphism might not be associated with overall cancer risk. However, well-designed, large-scale studies with different ethnic populations need to be conducted in the future to elucidate the potential association.

Crosstalk between prognostic long noncoding RNAs and messenger RNAs as transcriptional hallmarks in gastric cancer

AIM

Our study investigated the significance of the crosstalk between long noncoding RNAs (lncRNAs) and mRNAs in gastric cancer (GC).

METHODS

lncRNA and mRNA expression profiling data in 671 GC tumors and 77 nontumorous gastric tissues were retrieved from the gene expression omnibus database: GSE54129, GSE13911, GSE19826, GSE79973, GSE15459 and GSE66229. Differentially expressed analysis, RNA coexpression network construction, gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses were conducted in this study.

RESULTS

Using differentially expressed and prognostic lncRNAs or mRNAs in GC, we constructed the lncRNA-mRNA coexpression networks. This network involved with vital GO and KEGG pathways.

CONCLUSION

Our study reveals coexpressed lncRNAs and mRNAs as transcriptional hallmarks in GC patients which provide interesting information regarding the incidence and outcome of GC.

AFAP1-AS1: A novel oncogenic long non-coding RNA in human cancers

Long non-coding RNAs (lncRNAs), a group of non-protein-coding RNAs with more than 200 nucleotides in length, are involved in multiple biological processes, such as the proliferation, apoptosis, migration and invasion. Moreover, numerous studies have shown that lncRNAs play important roles as oncogenes or tumour suppressor genes in human cancers. In this paper, we concentrate on actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1), a well-known long non-coding RNA that is overexpressed in various tumour tissues and cell lines, including oesophageal cancer, pancreatic ductal adenocarcinoma, nasopharyngeal carcinoma, lung cancer, hepatocellular carcinoma, ovarian cancer, colorectal cancer, biliary tract cancer and gastric cancer. Moreover, high expression of AFAP1-AS1 was associated with the clinicopathological features and cancer progression. In this review, we sum up the current studies on the characteristics of AFAP1-AS1 in the biological function and mechanism of human cancers.

Interaction and cross-talk between non-coding RNAs

Non-coding RNA (ncRNA) has been shown to regulate diverse cellular processes and functions through controlling gene expression. Long non-coding RNAs (lncRNAs) act as a competing endogenous RNAs (ceRNAs) where microRNAs (miRNAs) and lncRNAs regulate each other through their biding sites. Interactions of miRNAs and lncRNAs have been reported to trigger decay of the targeted lncRNAs and have important roles in target gene regulation. These interactions form complicated and intertwined networks. Certain lncRNAs encode miRNAs and small nucleolar RNAs (snoRNAs), and may regulate expression of these small RNAs as precursors. SnoRNAs have also been reported to be precursors for PIWI-interacting RNAs (piRNAs) and thus may regulate the piRNAs as a precursor. These miRNAs and piRNAs target messenger RNAs (mRNAs) and regulate gene expression. In this review, we will present and discuss these interactions, cross-talk, and co-regulation of ncRNAs and gene regulation due to these interactions.

Ftx non coding RNA-derived miR-545 promotes cell proliferation by targeting RIG-I in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. Accumulating studies have demonstrated that aberrant expression of several lncRNAs was found to be involved in the hepatocarcinogenesis. In this study, a lncRNA Ftx was chosen to investigate its effects on HCC cells, and clarify the possible mechanism. We demonstrated that the lncRNA Ftx and Ftx-derived miR-545 were up-regulated in both HCC tissues and cells. MiR-545 was positively correlated with lncRNA Ftx expression. Notably, clinical association analysis revealed that the high expression of lncRNA Ftx and miR-545 was associated with poor prognostic features, and conferred a reduced 5-year overall survival (OS) and disease-free survival (DFS) of HCC patients. We found that miR-545 was a pivotal mediator in Ftx-induced promotion of HCC cell growth. Subsequently, we identified RIG-I as a direct target of miR-545. The expression of RIG-I was downregulated in HCC tissues and was inversely correlated with miR-545 expression. Our data revealed that ectopic expression of RIG-I abrogated the effects of lncRNA Ftx or miR-545 on HCC cells. LncRNA Ftx/miR-545-mediated downregulation of RIG-I led to increased Akt phosphorylation in vitro and in vivo. Inhibition of Akt phosphorylation abolished the effects of lncRNA Ftx/miR-545 on HCC cells. In conclusion, our study demonstrates that the novel pathway lncRNA Ftx/miR-545/RIG-I promotes HCC development by activating PI3K/Akt signaling, and it may serve as a novel prognostic biomarker and therapeutic target for HCC.

Long noncoding RNA H19 derived miR-675 regulates cell proliferation by down-regulating E2F-1 in human pancreatic ductal adenocarcinoma

The long noncoding RNA (lncRNA) H19 has been proven to be overexpressed in human pancreatic ductal adenocarcinoma (PDAC). H19-induced PDAC cell proliferation is cell cycle-dependent by modulating E2F-1. However, the mechanism of how H19 regulates E2F-1 remains unclear. In this study, we investigated the expression of miR-675 in PDAC tumours and cells, the biological function of miR-675 in PDAC cell proliferation and the possible relationship among H19, miR-675 and E2F-1. As a transcript of the first exon of H19, the level of miR-675 was negatively correlated with H19 expression in microdissected PDAC tissues (r=-0.0646, P=0.001). The serum miR-675 expression was significantly down-regulated in patients with PDAC compared to those in healthy individuals. Moreover, an evaluation of five PDAC cases showed that there was a remarkable increase of serum miR-675 levels after resection of the primary tumours. Ectopic overexpression of miR-675 in AsPC-1 and PANC-1 cells decreased cell viability, the colony-forming ability and the percentage of cells in S phase; contrarily, miR-675 knockdown resulted in enhanced cell proliferation. Furthermore, the suppressed cell proliferation caused by H19 knockdown could be rescued by inhibiting miR-675 expression. Additionally, intratumoural injection of either miR-675 agomir or antagomir could significantly affect tumour growth in vivo. Both the bioinformatic prediction and luciferase activity assay confirmed that E2F-1 was a direct target of miR-675. And the decrease of E2F-1 protein expression caused by siH19 could be partially reversed by miR-675 knockdown. We concluded that there might be a H19/miR-675/E2F-1 regulatory loop in cell cycle modulation. Serum miR-675 might serve as a potential biomarker for not only early diagnosis but also outcome prediction in PDAC.

NEAT1 upregulates EGCG-induced CTR1 to enhance cisplatin sensitivity in lung cancer cells

Platinum-based drugs are the firstline of treatment for non-small cell lung cancer (NSCLC), but resistance to these drugs is a major obstacle to effective chemotherapy. Our previous study revealed that the green tea polyphenol, EGCG, induced cisplatin transporter CTR1 (copper transporter 1) and enhanced cisplatin sensitivity in ovarian cancer. In this study, we found that EGCG upregulated CTR1 and increased platinum accumulation in NSCLC (A549, H460 and H1299) cells, cDDP-resistant A549 cells and a nude mouse xenograft model. Cisplatin-induced inhibition of cell growth was enhanced by EGCG treatment in vitro and in vivo. MicroRNA hsa-mir-98-5p appears to suppress CTR1 gene expression, while long non-coding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) appears to enhance it. Bioinformatics analysis showed that hsa-mir-98-5p has specific complementary binding sites for NEAT1. In addition, hsa-mir-98-5p was predicted to be a putative CTR1 target. NEAT1 may act as a competing endogenous lncRNA to upregulate EGCG-induced CTR1 by sponging hsa-mir-98-5p in NSCLC. Our findings reveal a novel mechanism how NEAT1 upregulates EGCG-induced CTR1 and enhances cisplatin sensitivity in vitro and in vivo, and suggest EGCG could serve as an effective adjuvant chemotherapeutic in lung cancer treatment.

LINC00473 antagonizes the tumour suppressor miR-195 to mediate the pathogenesis of Wilms tumour via IKKα

OBJECTIVES

Although dramatic improvements of overall survival has achieved in patients with favourable histology Wilms tumour, disease recurrence is still the main cause of cancer-related death in childhood. Long non-coding RNAs (lncRNAs) as oncogenes or tumour suppressors are dysregulated during carcinogenesis. However, the role of lncRNAs in the pathogenesis of Wilms tumour is unknown. Here, an lncRNA LINC00473 signature that functioned as oncogene was identified in Wilms tumour.

METHODS

Wilms tumour (n = 15) and relative normal tissues were collected. The LINC00473 expression and function in Wilms tumour was determined. The LncRNA-miRNA network of LINC00473 was analysed in vitro and vivo.

RESULTS

We uncovered that the expression of LINC00473 was elevated in tumour tissues than that in relative normal tissues. Higher LINC00473 levels correlated to higher stage and unfavourable histology Wilms tumour. Mechanistically, knockdown of LINC00473 inhibited cell vitality and induced Bcl-2-dependent apoptosis and G1/S arrest via CDK2 and cyclin D1. Moreover, LINC00473 harboured binding sites for miR-195 and limited miR-195 availability in a dose-dependent manner. Forced expression of miR-195 impaired tumour survival and metastasis, which, however, could be restored by LINC00473. Furthermore, IKKα was the downstream of LINC00473/miR-195 signals and could be directly targeted by miR-195 to participate LINC00473-induced tumour progression. Loss-of-function of LINC00473 in vivo effectively promoted the regression of Wilms tumour via miR-195/IKKα-mediated growth inhibition.

CONCLUSION

LINC00473 as an oncogene is up-regulated to participate into the molecular pathogenesis of Wilms tumour via miR-195/IKKα.