The functional role of long non-coding RNA in digestive system carcinomas

Comprehensive identification and analysis of circRNAs during hickory (Carya cathayensis Sarg.) flower bud differentiation

Flower bud differentiation represents a crucial transition from vegetative growth to reproductive development. Carya cathayensis (hickory) is an important economic species in China, with a long juvenile period that hinders its commercial development. In recent years, circular RNAs (circRNAs) have been widely studied and identified as sponges for miRNA regulation of mRNA expression. However, little is known regarding the role of circRNAs in flower buds. In this study, we sequenced circRNAs at three developmental stages (undifferentiated, differentiating, and fully differentiated) in both female and male buds. A total of 6,931 circRNAs were identified in the three developmental stages and 4,449 and 2,209 circRNAs were differentially expressed in female and male buds, respectively. Gene ontology demonstrated that many circRNA host genes participated in various processes, for example, cellular and intracellular pH regulation. Function annotation identified 46 differentially expressed circRNAs involved in flowering regulation, with 28 circRNAs found only in female buds, 4 found only in male buds, and 11 found in both female and male buds. A circRNA-miRNA-mRNA network was predicted based on 13 flowering-related circRNAs and their seven putative interacting miRNAs to describe the regulatory mechanism. Our preliminary results demonstrated a potential involvement of circRNA in bud differentiation. They provided a preliminary theoretical basis for how circRNA might participate in flower development in hickory, perhaps in woody plants.

LncRNA GAS5 Suppresses Colorectal Cancer Progress by Target miR-21/LIFR Axis

GAS5 is abnormally high in colorectal cancer tissues, which is a specific expression of lncRNA in colorectal cancer (CRC). Nevertheless, its biological function in CRC has not been elucidated. The abnormal high expression of GAS5 in CRC is the specific expression of lncRNA in CRC. The purpose of our study is to explore the effect of GAS5 on CRC and its mechanism. The expression of GAS5 in 53 paired normal and colorectal cancer tissues and colorectal cancer cell lines was detected by real-time PCR. The biological effects of GAS5, miR-21, and LIFR were measured by functional assays, including wound healing, transwell assays, and in vivo assays. We ensured the carcinogenesis role of GAS5 in CRC in the xenograft nude model. The dual-luciferase reporter assay system and chromatin immunoprecipitation method were used for target evaluation and Western blot for verification. GAS5 was significantly decreased in tumor tissues and CRC cells, and the low expression of CAS5 in CRC promoted tumor metastasis and decreased the survival of patients. GAS5 knockdown increases the cell viability, inhibits apoptosis, and promotes migration. Xenografted tumors in nude mice studies showed that GAS5 knockdown promoted tumor growth and caused worse lesions in colorectal. Furthermore, GAS5 increases the expression level of target gene LIFR to promote the apoptosis of CRC cells by binding to miR-21. Our study revealed that a novel pathway about lncRNA GAS5 inhibited the proliferation and metastasis of CRC cells by targeting miR-21/LIFR which provides a new strategy to treat CRC.

CORAZON: a web server for data normalization and unsupervised clustering based on expression profiles

Objective

Data normalization and clustering are mandatory steps in gene expression and downstream analyses, respectively. However, user-friendly implementations of these methodologies are available exclusively under expensive licensing agreements, or in stand-alone scripts developed, reflecting on a great obstacle for users with less computational skills.

Results

We developed an online tool called CORAZON (Correlations Analyses Zipper Online), which implements three unsupervised learning methods to cluster gene expression datasets in a friendly environment. It allows the usage of eight gene expression normalization/transformation methodologies and the attribute’s influence. The normalizations requiring the gene length only could be performed to RNA-seq, meanwhile the others can be used with microarray and/or NanoString data. Clustering methodologies performances were evaluated through five models with accuracies between 92 and 100%. We applied our tool to obtain functional insights of non-coding RNAs (ncRNAs) based on Gene Ontology enrichment of clusters in a dataset generated by the ENCODE project. The clusters where the majority of transcripts are coding genes were enriched in Cellular, Metabolic, Transports, and Systems Development categories. Meanwhile, the ncRNAs were enriched in the Detection of Stimulus, Sensory Perception, Immunological System, and Digestion categories. CORAZON source-code is freely available at https://gitlab.com/integrativebioinformatics/corazon and the web-server can be accessed at http://corazon.integrativebioinformatics.me.

LncRNA ZFAS1/miR-589 regulates the PTEN/PI3K/AKT signal pathway in the proliferation, invasion and migration of breast cancer cells

Breast cancer (BC) is a common clinical disease and the second leading cause of cancer death in women. Long noncoding RNA (lncRNA) and microRNA (miRNA) are reported to be involved in the development of BC. The present study aimed to investigate whether LncRNA ZFAS1 could regulate the proliferation, invasion and migration of breast cancer cells by targeting miR-589 through PTEN/PI3K/AKT signal pathway. The expression of ZFAS1 and miR-589 in BC cells and transfection effects were determined by RT-qPCR analysis. The abilities of proliferation, colony formation, invasion and migration of breast cancer cells were analyzed by CCK-8 assay, colony formation assay, transwell assay and wound healing assay respectively. The expression of MMP2, MMP9, Bcl2, Bax, cleaved caspase3, PTEN, p-PI3K, p-AKT, PI3K and AKT was detected by Western blot. The flow cytometry analysis was used to detect cell apoptosis. As a result, ZFAS1 expression was increased and miR-589 expression was decreased in BC cells. And, miR-589 was demonstrated to be a target of ZFAS1. ZFAS1 overexpression could inhibit the proliferation, colony formation, invasion and migration of BC cells while miR-589 overexpression could reverse the changes. In addition, ZFAS1 overexpression suppressed the expression of PI3K/AKT signal pathway by activating the PTEN expression while miR-589 overexpression could reverse the changes. Moreover, PTEN is one of the gene targets of miR-589. In conclusion, this study indicated that ZFAS1 inhibited the proliferation, invasion and migration of breast cancer cells by targeting miR-589 through regulating the PTEN/PI3K/AKT signal pathway.

Long noncoding RNA THAP9-AS1 is induced by Helicobacter pylori and promotes cell growth and migration of gastric cancer

Background

Long noncoding RNAs (LncRNAs) have been confirmed to play crucial roles in cancer biology. Gastric cancer (GC) is the third leading cause of cancer related death, and Helicobacter pylori (H. pylori) is the major risk factor for GC. In this study, we focused on the roles of H. pylori-related lncRNAs in the progression of GC.

Method

Differentially expressed lncRNAs were identified through RNA-seq analysis of H. pylori-infected GC cells.

Results

We found that the expression of the lncRNA THAP9-AS1 was up-regulated after infection of GC cells with H. pylori and was higher in GC tissues than in gastritis tissues. Colony formation, CCK8 and transwell assays were executed to show that THAP9-AS1 can promote GC cell proliferation and migration in vitro. Our study identified the pro-oncogenic lncRNA THAP9-AS1, which has a higher expression level in GC tissues than in gastritis tissues and which promoted the proliferation and migration of GC cells in vitro.

Conclusion

These findings may provide a potential therapeutic target for H. pylori-associated GC.

Prediction of Recurrence in Cervical Cancer Using a Nine-lncRNA Signature

Background and Objective

As a common cancer type in women, cervical cancer remains one of the leading causes of cancer-associated mortalities word wide. Recent evidence has demonstrated the regulatory role of a large number of long non-coding RNAs (lncRNAs) in cervical cancer. Here, we aimed to identify new biomarkers that related with the recurrence through comprehensive bioinformatics analysis.

Methods

Firstly, we collected online lncRNA expression data of cervical cancer patients which were divided into training, validation, and test set. Then we developed a nine-lncRNA signature from training set by conducting LASSO Cox regression model along with 10-fold cross validation. The prognostic value of this risk score was validated in all the three sets using Kaplan–Meier analysis, C-index, time-dependent ROC curves and dynamic AUC. Biological function of these lncRNAs in cervical cancer cells were evaluated by performing gene ontology biological process enrichment and Kyoto Encyclopedia of Genes and Genomes signaling pathways analysis.

Results

According to the results, a higher predict accuracy was observed in the nine-lncRNA signature than that of FIGO stage in all the three sets. Stratified analysis also demonstrated that the nine-lncRNA signature can predict the recurrence of cervical cancer within FIGO stage. The potential mechanisms underlying the nine-lncRNAs from the signature were also identified according to the gene enrichment analysis.

Conclusion

In the present article, we provided a reliable prognostic tool to facilitate the individual management of patients with cervical cancer after treatment.

Antitumor effects of circ-EPHB4 in hepatocellular carcinoma via inhibition of HIF-1α

The protein EPHB4 plays a vital role in various tumor types. However, few studies into the function of circ-EPHB4 (hsa_circ_0001730) in tumors have been conducted. This study aimed to investigate the functions of circ-EPHB4 and the underlying mechanism of circ-EPHB4 in regulating hepatocellular carcinoma (HCC). The expression of circ-EPHB4 was found to be downregulated in HCC tumor tissues, whereas circ-EPHB4 overexpression suppressed cell viability, induced apoptosis, and inhibited cell migration and invasion in Huh7 and HepG2 cells. circ-EPHB4 levels were negatively correlated with tumor weight, size, and metastasis foci in nude mouse models, suggesting circ-EPHB4 inhibits tumorigenesis, tumor development, and metastasis. In addition, HIF-1α and PI3K-AKT pathways were markedly affected by circ-EPHB4 overexpression. HIF-1α could potentially be the target of circ-EPHB4. By overexpressing both HIF-1α and circ-EPHB4, the antitumor effect of circ-EPHB4 should be most probably correlated with HIF-1α. In conclusion, circ-EPHB4 is a tumor inhibitor in HCC and functions by inhibiting HIF-1α expression.

Identification of a 26-lncRNAs Risk Model for Predicting Overall Survival of Cervical Squamous Cell Carcinoma Based on Integrated Bioinformatics Analysis

As a common malignancy in women, cervical squamous cell carcinoma is a major cause of cancer-related mortality globally. Recent studies have demonstrated that long non-coding RNA (lncRNA) can function as potential biomarkers in cancer prognosis; however, little is known about its role in cervical cancer. In this study, we downloaded the gene expression profiles along with the clinical data of patients with cervical squamous cell carcinoma from The Cancer Genome Atlas. By applying bioinformatics analysis including random forest selection and Least Absolute Shrinkage and Selection Operator (LASSO) cox regression model along with 10-fold cross-validation, we constructed a 26-lncRNAs risk model that can be used to predict the overall survival of cervical squamous cell carcinoma. After that, Kaplan-Meier analysis combined with log-rank p test was applied to assess the predictive accuracy of the 26-lncRNAs risk model. Further analysis showed that the prognostic value of 26-lncRNAs risk model was independent of other clinicopathological factors. At last, lncRNAs in the model were put into gene ontology biological process enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathways analysis, which suggested that these lncRNAs might contribute to cancer-associated processes such as cell cycle and apoptosis. This study indicated that lncRNAs signature could be a useful marker to predict the prognosis of cervical squamous cell carcinoma.

The lncRNA TUG1 promotes epithelial ovarian cancer cell proliferation and invasion via the WNT/β-catenin pathway

Purpose

Epithelial ovarian cancer (EOC) is among the most common malignant tumors of the endocrine system. Numerous studies have shown that genetic factors are important in the development of EOC, and there is evidence that long noncoding RNA molecules (lncRNAs) can regulate gene expression at the transcription, posttranscription, and epigenetic levels to influence cancer proliferation and invasion, cell differentiation, and apoptosis. However, the roles of lncRNAs in the pathogenesis of EOC remain unclear. Here, we investigated the role of the lncRNA, taurine upregulated gene 1 (TUG1), in EOC.

Patients and methods

TUG1 mRNA levels were evaluated in EOC and matched normal tissue samples and in EOC cell lines by quantitative real-time PCR. Lentiviral vectors expressing the lncRNA, TUG1, and siRNA targeting TUG1 were constructed and transfected into EOC cells. MTT and Transwell assays were used to determine the effects of TUG1 on cell proliferation, migration, and invasion. Western blotting was performed to determine the influence of TUG1 up- or downregulation on WNT/β-catenin signaling, which is involved in the occurrence and development of cancer.

Results

TUG1 expression was clearly elevated in EOC compared with control tissue and cells. Moreover, TUG1 expression was associated with lymphatic metastasis, T stage, and clinical stage in patients with EOC. Downregulation of TUG1 in EOC inhibited cell proliferation, migration, and invasion. In EOC cells, levels of the WNT/β-catenin pathway factors, β-catenin, cyclin D1, and c-Myc, were significantly up- and downregulated in response to TUG1 over- and underexpression, respectively.

Conclusion

Our data suggest that knockdown of TUG1 may represent a novel therapeutic approach for the management of EOC.

Geniposide suppresses growth, migration and invasion of MKN45 cells by down-regulation of lncRNA HULC

Gastric cancer (GC) is a serious disease with high incidence rate and high mortality. Geniposide (GEN) exhibits multiple biological properties including anti-tumor function. However, effect of GEN on GC is not well studied. Hence, the effects of GEN on GC were investigated in our study. HULC expression in GC tissue and GC cell lines (MKN45, SGC-7901, MKN28, AGS) was detected by qRT-PCR. Cell viability, colony formation, migration, invasion and cell apoptosis were examined by CCK-8 assay, survival fraction assay, modified two-chamber migration assay, Millicell Hanging Cell Culture and flow cytometry analysis, respectively. The expression of matrix metalloproteinase (MMP)-2/9 and vimentin was detected by qRT-PCR and western blot, respectively. The expression of PI3K/AKT and JNK was measured by western blot. The expression of HULC was up-regulated both in GC tissue and cell lines (P < .05, P < .01 or P < .001). GEN negatively regulated the expression of HULC in MKN45 cells (P < .05 or P < .01). GEN decreased cell viability (P < .05), colony formation (P < .01), migration (P < .05) and invasion (P < .05) while HULC overexpression led to the opposite results in GEN-treated cells. The expression of phosphatidylinositol 3' -kinase (PI3K)/ protein kinase B (AKT) and c-Jun N-terminal kinase (JNK) was down-regulated by GEN (all P < .05) while reversed by HULC overexpression. HULC was up-regulated in GC. GEN inhibited MNK45 cell viability, colony formation, migration and invasion while induced cell apoptosis by down-regulation of HULC in MKN45 cells. GEN inactivated PI3K/AKT and JNK signal pathways through down-regulation of HULC.

RETRACTED: The function of long non-coding RNA MT1JP in the development and progression of gastric cancer

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Executive Editor (Chairman) as panels from Figures 3A,B and 4D are similar to panels from Figures 4A,B and 5E of the article published by Mingjun Bi, Hongmei Yu, Bin Huang and Cuiyan Tang in Gene 626 (2017) 337–343 http://dx.doi.org/10.1016/j.gene.2017.05.049. Also, Figures 3C and 4A are similar to Figures 4C and 5A of the Gene article. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. As such this article represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Long non-coding RNA CASC15 regulates gastric cancer cell proliferation, migration and epithelial mesenchymal transition by targeting CDKN1A and ZEB1

Long non‐coding RNA (lncRNA) is responsible for a diverse range of cellular functions, such as transcriptional and translational regulation and variance in gene expression. The lncRNA CASC15 (cancer susceptibility candidate 15) is a long intergenic non‐coding RNA (lincRNA) locus in chromosome 6p22.3. Previous research shows that lncRNA CASC15 is implicated in the biological behaviors of several cancers such as neuroblastoma and melanoma. Here, we aimed to explore in detail how CASC15 contributes to the growth of gastric cancer (GC). As predicted, the expression of CASC15 was enriched in GC tissues and cell lines as compared with healthy tissues and cells using qRT‐PCR. The Kaplan–Meier method was used to demonstrate that high expression of CASC15 is linked to a poor prognosis for patients suffering from GC. Additionally, functional experiments proved that the down‐ or up‐regulation of CASC15 inhibited or facilitated cell proliferation via the induction of cell cycle arrest and apoptosis, and also suppressed or accelerated cell migration and invasion by affecting the progression of the epithelial‐to‐mesenchymal transition (EMT). In vivo experiments showed that the knockdown of CASC15 lessened the tumor volume and weight and influenced the EMT process. This was confirmed by western blot assays and immunohistochemistry, indicating impaired metastatic ability in nude mice. CASC15 involvement in the tumorigenesis of GC occurs when CASC15 interacts with EZH2 and WDR5 to modulate CDKN1A in nucleus. Additionally, the knockdown of CASC15 triggered the silencing of ZEB1 in cytoplasm, which was shown to be associated with the competitive binding of CASC15 to miR‐33a‐5p.

LncRNA TRERNA1 Function as an Enhancer of SNAI1 Promotes Gastric Cancer Metastasis by Regulating Epithelial-Mesenchymal Transition

Long noncoding RNA (lncRNA) has been implicated in cancer, but little is known about the role of lncRNAs as regulators of tumor metastasis. In the present study, we demonstrate that lncRNA TRERNA1 acts like an enhancer of SNAI1 to promote cell invasion and migration and to contribute to metastasis of gastric cancer (GC). TRERNA1 is significantly unregulated in GCs and GC cell lines. Increased TRERNA1 is positively correlated with lymph node metastasis of GCs. RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assays revealed that TRERNA1 functions as a scaffold to recruit EZH2 to epigenetically silence epithelial-mesenchymal transition marker CDH1 by H3K27me3 of its promoter region. TRERNA1 knockdown markedly reduced GC cell migration, invasion, tumorigenicity, and metastasis. Depletion of TRERNA1 reduced cell metastasis of GCs in vivo. Taken together, our findings indicated that TRERNA1 serves as a critical effector in GC progression by regulating CDH1 at the transcription level. It is implied that TRERNA1/CDH1 is a new potential target for GC therapy.

Long non-coding RNAs on the stage of cervical cancer (Review)

Cervical cancer is one of most malignant gynecological tumors. However, effective means for diagnosing and treating cervical cancer have yet to be identified. A few decades ago, long non-coding RNAs (lncRNAs) were regarded as useless parts of the genome, however, increasing data have demonstrated the importance of lncRNAs in the diagnosis and treatment of cervical cancers. The aim of the present study is to summarize the role(s) of HOTAIR, MALAT1, CCAT2, SPRY4-IT1, RSU1P2, CCHE1, lncRNA-EBIC and PVT1. Approximately 14 lncRNAs are involved in cervical cancer and several important proteins, miRNAs and other molecules and play crucial roles in a few traditional signaling pathways that have been proven to be related to those lncRNAs. In conclusion, lncRNAs may be useful as exact treatment targets and diagnostic biomarkers for improving therapies in cervical cancer patients and lncRNAs may contribute to effective diagnosis and treatment methods for cervical cancer.

Identification of a lncRNA involved functional module for esophageal cancer subtypes

Esophageal cancer (EC) is the sixth most common cause of death from cancer and has two principal histological subtypes: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). In addition, Barrett's esophagus (BE), due to its strong association with EAC, is generally considered to be a premalignant condition of EAC. lncRNAs are believed to function in initiation and progression of multiple cancers, and therefore should play prominent, but unknown roles in the determination and behavior of different EC subtypes. In this study, by using expression profile re-annotation and differential expression (DE) analysis, we identified DE-lncRNAs and DE-protein-coding genes (DE-PCGs), and then constructed a lncRNA-PCG network, using co-expressed DE-lncRNAs (550) and DE-PCGs (5236), which was also annotated for EC subtypes. After module mining of the network, we obtained twenty candidate lncRNA-PCG modules that were ranked by gene expression and subtype-specification. Within the top four modules, we identified an ESCC specific module, two EAC-BE-specific modules and a heterologous module. Novel candidate lncRNAs were identified, in addition to lncRNAs known to be functionally connected to EC, and could be responsible for the subtype disparities in the GO biological process and at pathway levels.

Long noncoding RNA MALAT1 affects the efficacy of radiotherapy for esophageal squamous cell carcinoma by regulating Cks1 expression

OBJECTIVE

Long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been well studied in the progression of many malignancies. However, its association with the radioresistance of tumors has not been well understood yet. This study tried to explore the role of MALAT1 in regulating the radiosensitivity of esophageal cancer (EC), especially esophageal squamous cell carcinoma (ESCC), involving its regulation on Cks1 expression.

METHODS

KYSE150 cells were subcutaneously inoculated into nude mice to establish ESCC xenografts. Real-time PCR and Western blot analysis were performed to detect the expression of MALAT1 and Cks1 in irradiated xenografts and cells. Functional analysis was performed in both EC9706 and KYSE150 cells via the transfection of corresponding plasmids or small interfering RNAs (siRNAs). Irradiation-induced damage was examined by the detection of cell viability and apoptosis using MTT and TUNEL assays, respectively.

RESULTS

Both MALAT1 and Cks1 were downregulated in irradiated xenografts and cells. Cks1FER1L4 showed significant downregulation. Overexpression of MALAT1 inhibited irradiation-induced decrease in cell viability, increase in apoptosis, and downregulation of Cks1. Cks1 expression was also downregulated by MALAT1 siRNA, while Cks1 siRNA strongly recovered MALAT1-induced radioresistance in vitro. Moreover, better tumor growth, accompanied by Cks1 upregulation, was observed in KYSE150 xenografts with MALAT1 overexpression, especially under radiation treatment.

CONCLUSION

MALAT1 acted as one positive regulator of the radioresistance of ESCC, at least partly due to its promotion on Cks1 expression. Furthermore, MALAT1-targeted therapies showed great potential in enhancing the radiotherapeutic effect on ESCC.

Long noncoding RNA NBAT-1 suppresses tumorigenesis and predicts favorable prognosis in ovarian cancer

Long noncoding RNA (lncRNA) has been proven to be involved in many biological processes in ovarian cancer (OC). However, the mechanism still remains unknown. In this study, we screened significantly downregulated NBAT-1, which has been proven to play a significant role in breast cancer, clear cell renal cell carcinoma, and neuroblastoma, but not in OC, in two independent datasets with relatively more samples (GSE18520 and GSE38666) from Gene Expression Omnibus. We found that lncRNA NBAT-1 was obviously downregulated in OC tissue compared to normal ovarian tissue (P<0.001) which was free of OC, and the detected levels of NBAT-1 were associated with the International Federation of Gynecology and Obstetrics stage and tumor size guidelines. Moreover, it has been shown that lower levels of NBAT-1 predict poor outcomes of OC. In order to investigate the functional role of NBAT-1, pcDNA-NBAT-1 and empty vector were transfected into TOV112D and OVCAR-3 cell lines. Overexpressed NBAT-1 significantly inhibited cell proliferation, invasion, and migration in both TOV112D and OVCAR-3 cell lines. Finally, Western blot assay indicated that NBAT-1 may exert its function by targeting the ERK1/2 and AKT signaling pathways. In addition, tumor formation growth assay showed that overexpressed NBAT-1 significantly suppresses tumor growth in vivo. In conclusion, our study suggests that NBAT-1 acts as an anti-oncogene in the development of OC.

Suppression of PDCD4 mediated by the long non-coding RNA HOTAIR inhibits the proliferation and invasion of glioma cells

Programmed cell death protein 4 (PDCD4) has recently been demonstrated to be implicated in translation and transcription, and the regulation of cell growth. However, the mechanisms underlying PDCD4 function in glioma cells remain to be elucidated. The current study investigated the function and regulation of PDCD4 and the results demonstrated that the expression of PDCD4 was significantly reduced in glioma cells compared with normal cells. When PDCD4 was overexpressed in glioma cells, the proliferation rate and invasive capability of the cells greatly decreased, suggesting that PDCD4 functions as a tumor suppressor in this cell type. In addition, the histone modification status of the PDCD4 gene was analyzed, and chromatin immunoprecipitation assay identified a high density of histone 3 lysine 27 trimethylation on the promoter of PDCD4, which was associated with the long non-coding RNA, homeobox transcript antisense RNA (HOTAIR). The expression of HOTAIR was significantly increased in glioma cells compared with normal cells, and it exerted its function in a polycomb repressive complex 2-dependent manner. These results may provide novel approaches to therapeutically target PDCD4 and HOTAIR in patients with gliomas.

LncRNA HULC enhances epithelial-mesenchymal transition to promote tumorigenesis and metastasis of hepatocellular carcinoma via the miR-200a-3p/ZEB1 signaling pathway

Highly upregulated in liver cancer (HULC), a lncRNA that is considered a key molecule in human liver cancer, has recently been revealed to be involved in hepatocellular carcinoma (HCC) development and progression [1, 2]. It has been reported that HULC can promote tumor invasion and metastasis of HCC, but its function and mechanism of action in HCC have not been elucidated. In this study, we found that HULC was aberrantly up-regulated in HCC tissues and associated with TNM stage, intrahepatic metastases, HCC recurrence, and postoperative survival. HULC depletion inhibited the growth and metastasis of HCC cell lines in vitro and in vivo. Moreover, HULC contributes to ZEB1-induced epithelial-mesenchymal transition (EMT), a requirement for tumor invasion and metastasis that plays a key role in cancer progression. This effect of ZEB1 was inhibited by HULC siRNA. We conclude that the HULC functioned as a competing endogenous RNA (ceRNA) to mediate EMT via up-regulating ZEB1. In this way, it sequesters the miR-200a-3p signaling pathway to facilitate HCC metastasis. HULC comes into play as an oncogene in HCC, acting mechanistically by inducing HCC cells to activate EMT. Such an effect promotes tumor progression and metastasis through the miR-200a-3p/ZEB1 signaling pathway. The identification of this novel pathway that links high expression levels of HULC with EMT in HCC cells may serve as the foundation for the development of novel anti-tumor therapeutics.

LncRNAs: key players and novel insights into cervical cancer

Cervical cancer contributed the second highest number of deaths in female cancers, exceeded only by breast cancer, carrying high risks of morbidity and mortality. There was a great need and urgency in searching novel treatment targets and prognosis biomarkers to improve the survival rate of cervical cancer patients. Many long non-coding RNAs (lncRNAs) were emerging as pivotal regulators in various biological processes and took vitally an effect on the oncogenesis and progression of cervical cancer. In this review, we summarized the origin and overview function of lncRNAs; highlighted the roles of lncRNAs in cervical cancer in terms of prognosis and tumor progression, invasion and metastasis, apoptosis, and radio-resistance; and outlined the molecular mechanisms of lncRNAs in cervical cancer from the aspects of the interaction of lncRNAs with proteins/mRNAs (especially in HPV protein) and miRNAs, as well as RNA N-methyladenosine (m6A) methylation of lncRNAs. Meanwhile, the application of lncRNAs as biomarkers in cervical cancer prognosis and predictors for metastasis was also discussed. An overview of these researches will be valuable for broadening horizons into mechanisms, selection of meritorious biomarkers for diagnosis as well as prognosis, and future targeted therapy of cervical cancer.

Novel perspectives of long non-coding RNAs in esophageal carcinoma

Esophageal carcinoma (EC) is one of the most aggressive cancer types worldwide. However, the underlying genomic events of EC are not fully understood. It is becoming evident that long non-coding RNAs (lncRNAs) play vital roles in tumorgenesis, metastasis, prognosis and diagnosis. Accumulating EC-related lncRNAs have been verified to involve in various biological processes through diverse functions including signal, decoy, scaffold and guide. However, the molecular mechanism of lncRNAs in EC has not been fully explored. In this review, we outline the functions and underlying mechanism of EC-related lncRNAs to pave the way for identification of novel potential biomarkers for EC.

Aberrant expression of UCA1 in gastric cancer and its clinical significance

Long noncoding RNAs (lncRNAs) have been shown to regulate tumor biology and might be used for cancer diagnosis, prognosis and potential therapeutic targets. Although up-regulation of lncRNA UCA1 (urothelial carcinoma-associated 1) in several cancers has been found, its role in gastric cancer remains elusive. The aim of this study was to detect the expression of lncRNA UCA1 in gastric cancer and its clinical association. The expression of UCA1 was detected in 112 pairs of tumorous and adjacent normal tissues from patients with gastric cancer, as well as in four gastric cancer cell lines and a human normal gastric epithelium cell line using RT-qPCR. Results showed that UCA1 expression was remarkably increased in gastric cancer tissues and cell lines compared with that in the normal control. Clinicopathologic analysis revealed that high UCA1 expression correlated with worse differentiation, tumor size, invasion depth and TNM stage in gastric cancer. Kaplan-Meier analysis showed that increased UCA1 expression contributed to poor overall survival (p = 0.017) and disease-free survival (p = 0.024) of patients. A multivariate survival analysis also indicated that UCA1 could be an independent prognostic marker. The levels of UCA1 in gastric juice from gastric patients were significantly higher than those from normal subjects (p = 0.016). Moreover, validation analysis showed that UCA1 levels were robust in differentiating gastric cancer patients from control subjects [area under the curve (AUC) = 0.721; 95 % confidence interval (CI) = 0.655-0.788, p < 0.01]. These results suggested that UCA1 might serve as a promising biomarker for early detection and prognosis prediction of gastric cancer.