HOTAIR is a negative prognostic factor and exhibits pro-oncogenic activity in pancreatic cancer

Long Noncoding RNA in Preeclampsia: Transcriptional Noise or Innovative Indicators?

Preeclampsia (PE) is termed as an obstetric issue that is characterized by hypertension (≧140/90 mm Hg), together with proteinuria following 20 weeks of pregnancy. Until today, PE still constitutes a severe threat to the lives of both the mothers and fetuses. In the past, long noncoding RNAs (lncRNAs) were considered as the transcriptional noise. However, some investigations have indicated that lncRNAs could be used as innovative indicators in PE. The current review aims to discuss the relationship between lncRNAs and PE in recent years. According to the retrieved data, we concluded that lncRNAs can exert an impact on both the occurrence and development of PE through the changes in the biological functions of trophoblasts, immune regulation, epigenetic regulation, decidualization, and energy metabolism. The mechanisms of lncRNAs in PE will help us to better understand the pathogenesis of PE and help us to find targets for predicting and diagnosing PE in the future.

Molecular mechanisms of long noncoding RNAs-mediated cancer metastasis

Cancer metastasis is a multistep process that requires cancer cells to leave the primary site, survive in the blood stream, and finally colonize at a distant organ. It is the major cause of cancer morbidity and mortality. The organ-specific colonization requires close interaction and communication between cancer cells and host organs. Noncoding RNAs represent the majority of the transcriptome, with long noncoding RNAs (lncRNAs) making up a significant proportion. It has been suggested that lncRNAs play a key role in all stages of tumorigenesis and metastasis. This review will provide an overview of how lncRNAs are involved in cancer cell colonization in specific organ sites and the underlying mechanisms as well as therapeutic strategies.

From biomarkers to therapeutic targets-the promises and perils of long non-coding RNAs in cancer

Biomarker-driven personalized cancer therapy is a field of growing interest, and several molecular tests have been developed to detect biomarkers that predict, e.g., response of cancers to particular therapies. Identification of these molecules and understanding their molecular mechanisms is important for cancer prognosis and the development of therapeutics for late stage diseases. In the past, significant efforts have been placed on the discovery of protein or DNA-based biomarkers while only recently the class of long non-coding RNA (lncRNA) has emerged as a new category of biomarker. The mammalian genome is pervasively transcribed yielding a vast amount of non-protein-coding RNAs including lncRNAs. Hence, these transcripts represent a rich source of information that has the potential to significantly contribute to precision medicine in the future. Importantly, many lncRNAs are differentially expressed in carcinomas and they are emerging as potent regulators of tumor progression and metastasis. Here, we will highlight prime examples of lncRNAs that serve as marker for cancer progression or therapy response and which might represent promising therapeutic targets. Furthermore, we will introduce lncRNA targeting tools and strategies, and we will discuss potential pitfalls in translating these into clinical trials.

Long non-coding RNA HOTAIR regulates proliferation, migration and invasion of human cervical cancer cells by modulating expression of MAPK1

INTRODUCTION

Accumulating evidence suggests that long non-coding RNAs (lncRNAs) are dysregulated in cancer cells and may be responsible for the development and progression of this disease. Herein, the role and therapeutic potential of aberrantly expressed lncRNA HOTAIR were investigated in cervical cancer.

MATERIAL AND METHODS

The expression profile of the lncRNA HOTAIR was determined by quantitative RT-PCR. CCK-8 and colony formation assays were used for determination of cell viability. DAPI and annexin V/PI assays were used for detection of apoptosis. Wound healing and transwell assays were used to monitor cell migration and invasion.

RESULTS

The results showed that the expression of lncRNA HOTAIR was significantly (p < 0.01) upregulated (up to 4.1-fold) in cervical cancer cell lines. Silencing of lncRNA HOTAIR expression resulted in inhibition of the proliferation of the DoTc2 cervical cancer cells via induction of apoptotic cell death. HOTAIR silencing also resulted in decrease of the migration and the invasive properties of the cervical cancer cells. HOTAIR has been reported to interact with MAPK1 in cancer cells, and in this study MAPK1 was found to be overexpressed (up to 3.7-fold) in all the cervical cancer cells and silencing of HOTAIR inhibited the expression of MAPK1 in DoTc2 cervical cancer cells. Silencing of MAPK1 in DoTc2 cells also inhibited their proliferation and metastasis via induction of apoptosis. Co-transfection experiments showed that silencing of MAPK1 and lncRNA HOTAIR causes inhibition of DoTc2 cell growth synergistically.

CONCLUSIONS

These results indicate that lncRNA HOTAIR may prove to be an important therapeutic target for management of cervical cancer.

Expanding the Role of the Histone Lysine-Specific Demethylase LSD1 in Cancer

Studies of alterations in histone methylation in cancer have led to the identification of histone methyltransferases and demethylases as novel targets for therapy. Lysine-specific demethylase 1 (LSD1, also known as KDM1A), demethylates H3K4me1/2, or H3K9me1/2 in a context-dependent manner. In addition to the well-studied role of LSD1 in the epigenetic regulation of histone methylation changes, LSD1 regulates the methylation dynamic of several non-histone proteins and participates in the assembly of different long noncoding RNA (lncRNA_ complexes. LSD1 is highly expressed in various cancers, playing a pivotal role in different cancer-related processes. Here, we summarized recent findings on the role of LSD1 in the regulation of different biological processes in cancer cells through dynamic methylation of non-histone proteins and physical association with dedicated lncRNA.

Long non-coding RNAs: Functional regulatory players in breast cancer

Historically, the long-held protein-centered bias has denoted 98% of the human genome as 'Junk' DNA. However, the current work has shifted the perception of such 'junk' transcriptional products to functional regulatory molecules. The recent surveillance of the human transcriptome has highlighted the pivotal role of such non-coding RNA (ncRNA) molecules in diverse physiological and pathological conditions. Long non-coding RNA (lncRNA) is a recent class of ncRNA molecules that is still in its infancy stage. The main focus of this review is to unravel the importance of lncRNAs in the most prevalent malignancy among females which is Breast Cancer (BC). A specific focus on lncRNAs as prognostic markers among BC patients showing molecular subtype heterogeneity was also tackled in this review. Finally, the functional and the mechanistic roles of such booming ncRNA molecules in shaping the fate of the BC progression have been highlighted.

In Situ Hybridization Analysis of Long Non-coding RNAs MALAT1 and HOTAIR in Gastroenteropancreatic Neuroendocrine Neoplasms

Recent studies suggest onco-regulatory roles for two long non-coding RNAs (lncRNAs), MALAT1 and HOTAIR, in various malignancies; however, these lncRNAs have not been previously examined in neuroendocrine neoplasms (NENs) of gastroenteropancreatic origins (GEP-NENs). In this study, we evaluated the expressions and prognostic significance of MALAT1 and HOTAIR in 83 cases of GEP-NENs (60 grade 1, 17 grade 2, and 6 grade 3 tumors) diagnosed during the years 2005-2017. Expression levels of MALAT1 and HOTAIR were digitally quantitated in assembled tissue microarray slides labeled by chromogenic in situ hybridization (ISH) using InForm 1.4.0 software. We found diffuse nuclear expression of both HOTAIR and MALAT1 in all primary tumors of GEP-NENs with variable intensities. By multivariate model which adjusted for age and histologic grade, high expression of HOTAIR was associated with lower presenting T and M stages and subsequent development of metastases (P < 0.05). MALAT1 expression was associated with presenting T stage and development of metastases (P < 0.05). In summary, MALAT1 and HOTAIR are commonly expressed in GEP-NENs. High expression of either lncRNA showed grade-independent associations with clinically less aggressive disease.

Functional polymorphisms in LncRNA HOTAIR contribute to susceptibility of pancreatic cancer

Background

Pancreatic cancer (PC) remains one of the most aggressive cancers worldwide. However, genetic factors underlying PC susceptibility remain largely unclear. Long noncoding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) acts as an oncogene and its genetic variation has been linked to many cancers. However, the associations between genetic variants in HOTAIR gene and PC risk has not yet been reported.

Methods

A two-stage, case–control study was conducted to investigate the associations between HOTAIR SNPs and the PC risk. Dual luciferase reporter assay and real-time -PCR (RT-PCR) was conducted to evaluate the potential regulatory function of HOTAIR rs4759314 and rs200349340.

Results

We found the minor alleles of rs4759314 (OR = 1.76; 95 CI 1.37–2.25; P = 0.001) and rs200349340 (OR = 1.32; 95 CI 1.12–1.56; P = 0.001) were significantly associated with PC susceptibility. In functional experiments, we found subjects carrying the minor alleles of rs4759314 and rs200349340 had significantly higher HOTAIR RNA levels (mean ± SD) than those carrying the major alleles in PC tissues. For rs4759314, cells transfected with rs4759314 -G allele construct showed higher relative luciferase activity; while for rs200349340, cells transfected with rs200349340 -G allele construct showed more sensitive change of the relative luciferase activity.

Conclusion

Our studies revealed that functional SNP rs4759314 and rs200349340 of HOTAIR had strong associations with PC susceptibility. These findings elucidate that functional genetic variants influencing lncRNA expression may explain a portion of PC genetic basis.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0761-x) contains supplementary material, which is available to authorized users.

A Panel of 12-lncRNA Signature Predicts Survival of Pancreatic Adenocarcinoma

Background: Recent studies have highlighted the important roles of long non-coding RNAs (lncRNAs) in pancreatic adenocarcinoma (PCa) prognosis. However, most studies explored a limited number of lncRNAs based on small sample size.

Methods: Systematic and comprehensive analysis of the data from The Cancer Genome Atlas (TCGA) was performed to identify a panel of lncRNA signature for predicting prognosis in PCa.

Results: A total of 160 PCa patients with complete clinical data were included in our study. Twelve lncRNAs were identified to be significantly associated with overall survival (OS) in PCa patients using Cox regression analysis. A risk score formula was constructed to assess the prognostic value of the lncRNA signature in PCa. Patients with high risk score had worse OS than those with low risk score. The multivariate Cox regression analyses revealed that the lncRNA signature was an independent prognostic factor. Additionally, the signature might act as an indicator to predict treatment outcome. Functional enrichment analyses showed that the lncRNAs might involve in several molecular pathways closely related with PCa such as DNA replication, pancreatic cancer and regulation of tor signaling.

Conclusions: Our study demonstrated a lncRNA signature including 12 lncRNAs with the potential to be served as an independent prognostic biomarker of PCa.

Splicing and cancer: Challenges and opportunities

Cancer arises from alterations in several metabolic processes affecting proliferation, growth, replication and death of cells. A fundamental challenge in the study of cancer biology is to uncover molecular mechanisms that lead to malignant cellular transformation. Recent genomic analyses revealed that many molecular alterations observed in cancers come from modifications in the splicing process, including mutations in pre-mRNA regulatory sequences, mutations in spliceosome components, and altered ratio of specific splicing regulators. While alterations in splice site preferences might generate alternative isoforms enabling different biological functions, these might also be responsible for nonfunctional isoforms that can eventually cause dysregulation in cellular processes. Molecular characteristics of regulatory sequences and proteins might also be important prognostic tools revealing a cancer-specific splicing pattern and linking splicing control to cancer development. The connection between cancer biology and splicing regulation is of primary importance to understand the mechanisms leading to disease and also to improve development of therapeutic approaches. Splicing modulation is being explored in new anti-cancer therapies and further investigation of targeted splicing factors is critical for the success of these strategies. This article is categorized under: RNA Processing > Splicing Mechanisms RNA-Based Catalysis > RNA Catalysis in Splicing and Translation RNA Processing > Splicing Regulation/Alternative Splicing RNA in Disease and Development > RNA in Disease.

Targeted design and identification of AC1NOD4Q to block activity of HOTAIR by abrogating the scaffold interaction with EZH2

Background

Nearly 25% of long intergenic non-coding RNAs (lincRNAs) recruit chromatin-modifying proteins (e.g., EZH2) to silence target genes. HOX antisense intergenic RNA (HOTAIR) is deregulated in diverse cancers and could be an independent and powerful predictor of eventual metastasis and death. Yet, it is challenging to develop small molecule drugs to block activity of HOTAIR with high specificity in a short time.

Results

Our previous study proved that the 5′ domain, but not its 3′ domain, was the function domain of HOTAIR responsible for tumorigenesis and metastasis in glioblastoma and breast cancer, by recruiting and binding EZH2. Here, we targeted to establish a structure-based methodology to identify lead compounds of HOTAIR, by abrogating scaffold interactions with EZH2. And a small compound AC1NOD4Q (ADQ) was identified by high-throughput molecular docking-based virtual screening of the PubChem library. Our analysis revealed that ADQ was sufficiently and specifically interfering HOTAIR/EZH2 interaction, thereby impairing the H3K27-mediated tri-methylation of NLK, the target of HOTAIR gene, and consequently inhibiting tumor metastasis through Wnt/β-catenin pathway in vitro and in orthotopic breast cancer models. The results of RIP and EMSA further revealed that 36G46A of 5′ domain was the essential binding site for ADQ exerted its inhibitory effect, further narrowed the structure and function of HOTAIR from the 5′ functional domain to the micro-domain.

Conclusions

Our findings suggest of a potential new strategy to discover the lead compound for targeted lincRNA therapy and potentially pave the way for exploiting ADQ as a scaffold for more effective small molecule drugs.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0624-2) contains supplementary material, which is available to authorized users.

Inhibition of LINC00994 represses malignant behaviors of pancreatic cancer cells: interacting with miR-765-3p/RUNX2 axis

Pancreatic cancer exhibits one of the worst prognosis of all human cancers, and it is associated with gene dysregulation. Our microarray results first indicated long intergenic non-protein coding RNA 994 (LINC00994) as an upregulated long non-coding RNA (lncRNA) and miR-765-3p as a downregulated microRNA (miRNA) in pancreatic cancer tissues (Fold change ≥ 2 and P < 0.05; three paired samples). To investigate the role of LINC00994 in pancreatic carcinogenesis, a pair of short hairpin RNA (shRNA) was used to stably knock down the endogenous expression of LINC00994 in Panc-1 and AsPC-1 pancreatic cancer cells in vitro. We found that LINC00994 silencing inhibited the growth, migration and invasion, and promoted the G1 cell cycle arrest and apoptosis in Panc-1 and AsPC-1 cells. Furthermore, the expression of LINC00994 was negatively correlated with that of miR-765-3p in 10 pancreatic cancer specimens. Runt-related transcription factor 2 (RUNX2), a molecule that contributes to the aggressive behaviors of pancreatic cancer, was herein verified as a novel target for miR-765-3p. Like LINC00994, its expression was elevated in pancreatic cancers. Silencing of LINC00994 and RUNX2 reduced each other's expression in both Panc-1 and AsPC-1 cells. RUNX2 3'UTR and LINC00994 competed to bind miR-765-3p. Additionally, LINC00994-silenced cells regained their aggressive behaviors when miR-765-3p was antagonized, which was accompanied with RUNX2 re-expression. Collectively, our study reveals that LINC00994 contributes to the malignant behaviors of pancreatic cancer cells by preventing miR-765-3p from targeting RUNX2. LINC00994 can be considered as a novel therapeutic target against pancreatic cancer.

Paeonol reverses promoting effect of the HOTAIR/miR-124/Notch1 axis on renal interstitial fibrosis in a rat model

Renal interstitial fibrosis (RIF) is a common manifestation of inflammatory and noninflammatory renal diseases, which correlates to renal excretory dysfunction. Recently, the long noncoding RNAs (lncRNAs) have been demonstrated to be involved in the development of various renal diseases. Here, we aim to determine whether paeonol (PAE) affects RIF with involvement of the lncRNA HOX transcript antisense intergenic RNA (HOTAIR)/microRNA-124 (miR-124)/Notch1 axis. RIF rat models were established by performing unilateral ureteral occlusion (UUO), in which interactions between HOTAIR, Notch1, and miR-124 were determined. To identify the roles of PAE and HOTAIR in RIF, rats were injected with HOTAIR or PAE. Subsequently, to further investigate the underlying mechanism of PAE in RIF, epithelial to mesenchymal transition (EMT)- and migration-related genes in NRK-49F cells were measured. Next, rats were further treated with IMR-1 (inhibitor of the Notch1/Jagged1 signaling pathway) to determine how PAE influences the Notch1/Jagged1 signaling pathway. HOTAIR interacted with miR-124, and miR-124 directly targeted Notch1, and HOTAIR was observed to be upregulated in RIF rats. PAE was found to decrease HOTAIR and Notch1 expression but to increase the miR-124 expression in RIF rats. PAE inhibited EMT and migration of NRK-49F cells facilitated by HOTAIR. HOTAIR activated the Notch1/Jagged1 signaling pathway by downregulating miR-124, while PAE reversed these effects of HOTAIR on the Notch1/Jagged1 signaling pathway. Overall, our study demonstrates the contributory effect of lncRNA HOTAIR on RIF by activating the Notch1/Jagged1 signaling pathway via inhibition of miR-124, whereas administration of PAE can alleviate the effects of HOTAIR on RIF.

Genome-Wide Screening and Functional Analysis Identifies Tumor Suppressor Long Noncoding RNAs Epigenetically Silenced in Hepatocellular Carcinoma

Long noncoding RNAs (lncRNA) play critical roles in the development of cancer, including hepatocellular carcinoma (HCC). However, the mechanisms underlying their deregulation remain largely unexplored. In this study, we report that two lncRNAs frequently downregulated in HCC function as tumor suppressors and are epigenetically silenced by histone methyltransferase EZH2. lncRNAs TCAM1P-004 and RP11-598D14.1 were inhibited by EZH-mediated trimethylation of H3K27me3 at their promoters. Downregulation of TCAM1P-004 and RP11-598D14.1 was frequently observed in HCC tumors compared with adjacent normal tissues. Both lncRNAs inhibited cell growth, cell survival, and transformation in HCC cells in vitro as well as tumor formation in vivo. Using RNA pull-down and mass spectrometry, we demonstrated that TCAM1P-004 bound IGF2BP1 and HIST1H1C, whereas RP11-598D14.1 bound IGF2BP1 and STAU1. These lncRNA-protein interactions were critical in regulating p53, MAPK, and HIF1α pathways that promoted cell proliferation in HCC. Overexpression of EZH2 was critical in repressing TCAM1P-004 and RP11-598D14.1, and EZH2-TCAM1P-004/RP11-598D14.1-regulated pathways were prevalent in human HCC. Aberrant suppression of TCAM1P-004 and RP11-598D14.1 led to loss of their tumor-suppressive effects by disrupting the interaction with IGF2BP1, HIST1H1C, and STAU1, which in turn promoted HCC development and progression. Collectively, these findings demonstrate the role of TCAMP1P-004 and RP11-598D14.1 in suppressing tumor growth and suggest that EZH2 may serve as a therapeutic target in HCC. SIGNIFICANCE: EZH2-mediated loss of lncRNAs TCAM1P-004 and RP11-598D14.1 hinders the formation of tumor suppressor lncRNA-protein complexes and subsequently promotes HCC growth.

Involvement of long non-coding RNA HULC (highly up-regulated in liver cancer) in pathogenesis and implications for therapeutic intervention

INTRODUCTION

HULC (highly upregulated in liver cancer) is a long non-coding RNA (lncRNA) which is, as its name suggests, highly upregulated in hepatocellular carcinoma and in several other cancers. Increased HULC expression levels are strongly associated with clinicopathologic features such as tumor stages and overall survival and is a driver of tumor proliferation, migration, and invasion. Areas covered: This review addresses the discovery of HULC and discusses the consequences of HULC deregulation in cancer, the underlying molecular mechanisms and the potential of HULC as a biomarker and therapeutic target. Expert opinion: HULC is a promising candidate as a therapeutic target in cancer; however, more studies are necessary to further elucidate the underlying molecular mechanism(s), especially in cancer types other than hepatocellular carcinomas. Future studies that focus on an optimized HULC-targeting approach are necessary to clarify the best strategy to target this lncRNA in vivo and in patients.

Transcriptomic analysis reveals key lncRNAs associated with ribosomal biogenesis and epidermis differentiation in head and neck squamous cell carcinoma

OBJECTIVE

In this study, we aimed to expand current knowledge of head and neck squamous cell carcinoma (HNSCC)-associated long noncoding RNAs (lncRNAs), and to discover potential lncRNA prognostic biomarkers for HNSCC based on next-generation RNA-seq.

METHODS

RNA-seq data of 546 samples from patients with HNSCC were downloaded from The Cancer Genome Atlas (TCGA), including 43 paired samples of tumor tissue and adjacent normal tissue. An integrated analysis incorporating differential expression, weighted gene co-expression networks, functional enrichment, clinical parameters, and survival analysis was conducted to discover HNSCC-associated lncRNAs. The function of CYTOR was verified by cell-based experiments. To further identify lncRNAs with prognostic significance, a multivariate Cox proportional hazard regression analysis was performed. The identified lncRNAs were validated with an independent cohort using clinical feature relevance analysis and multivariate Cox regression analysis.

RESULTS

We identified nine HNSCC-relevant lncRNAs likely to play pivotal roles in HNSCC onset and development. By functional enrichment analysis, we revealed that CYTOR might participate in the multistep pathological processes of cancer, such as ribosome biogenesis and maintenance of genomic stability. CYTOR was identified to be positively correlated with lymph node metastasis, and significantly negatively correlated with overall survival (OS) and disease free survival (DFS) of HNSCC patients. Moreover, CYTOR inhibited cell apoptosis following treatment with the chemotherapeutic drug diamminedichloroplatinum (DDP). HCG22, the most dramatically down-regulated lncRNA in tumor tissue, may function in epidermis differentiation. It was also significantly associated with several clinical features of patients with HNSCC, and positively correlated with patient survival. CYTOR and HCG22 maintained their prognostic values independent of several clinical features in multivariate Cox hazards analysis. Notably, validation either based on an independent HNSCC cohort or by laboratory experiments confirmed these findings.

CONCLUSIONS

Our transcriptomic analysis suggested that dysregulation of these HNSCC-associated lncRNAs might be involved in HNSCC oncogenesis and progression. Moreover, CYTOR and HCG22 were confirmed as two independent prognostic factors for HNSCC patient survival, providing new insights into the roles of these lncRNAs in HNSCC as well as clinical applications.

Mechanisms of Antisense Transcription Initiation with Implications in Gene Expression, Genomic Integrity and Disease Pathogenesis

Non-coding antisense transcripts arise from the strand opposite the sense strand. Over 70% of the human genome generates non-coding antisense transcripts while less than 2% of the genome codes for proteins. Antisense transcripts and/or the act of antisense transcription regulate gene expression and genome integrity by interfering with sense transcription and modulating histone modifications or DNA methylation. Hence, they have significant pathological and physiological relevance. Indeed, antisense transcripts were found to be associated with various diseases including cancer, diabetes, cardiac and neurodegenerative disorders, and, thus, have promising potentials for prognostic and diagnostic markers and therapeutic development. However, it is not clearly understood how antisense transcription is initiated and epigenetically regulated. Such knowledge would provide new insights into the regulation of antisense transcription, and hence disease pathogenesis with therapeutic development. The recent studies on antisense transcription initiation and its epigenetic regulation, which are limited, are discussed here. Furthermore, we concisely describe how antisense transcription/transcripts regulate gene expression and genome integrity with implications in disease pathogenesis and therapeutic development.

Silencing of long noncoding RNA LINC00958 prevents tumor initiation of pancreatic cancer by acting as a sponge of microRNA-330-5p to down-regulate PAX8

Pancreatic cancer (PC) represents a relatively rare but severe malignancy worldwide. Accumulated studies have emphasized the potential of long noncoding RNA (lncRNA) as therapeutic strategies for several human cancers. Thus, we aimed to investigate whether a novel non-coding RNA regulatory circuitry involved in PC. Aberrantly expressed lncRNAs and mRNAs were screened out of microarray database. Following the determination of RNA expression, PANC-1 and BxPC-3 PC cells were adopted, after which the expression of miR-330-5p, PAX8 and LINC00958 were subsequently altered. RNA crosstalk was validated by dual-luciferase reporter gene assay. In order to detect whether LINC00958 could act as ceRNA to competitively sponge miR-330-5p and regulate PAX8, subcellular location of LINC00958 and interaction between LINC00958 and miR-330-5p were measured by FISH and RNA pull down respectively. The epithelial mesenchymal transition (EMT) process, cell invasion, and tumor growth were determined in vitro and in vivo. LINC00958 and PAX8 were up-regulated, while miR-330-5p was down-regulated during PC. LINC00958 mainly expressed in the cytoplasm and LINC00958 competitively sponged miR-330-5p. Upregulated miR-330-5p or downregulated PAX8 inhibited the EMT process as well as the invasion and metastasis ability of the PC cells. Moreover, the results indicated that miR-330-5p negatively targeted PAX8, and LINC00958 ultimately showcasing its ability to bind to miR-330-5p through its interaction with AGO2. Therefore, silencing of LINC00958 may bind to miR-330-5p to inhibit PAX8 in a competitive fashion, thereby preventing the progression of PC.

Four lncRNAs associated with breast cancer prognosis identified by coexpression network analysis

Previous studies on long noncoding RNA (lncRNA) have made breakthroughs in the treatment of several tumors, and these findings have brought attention to the lncRNA signature of breast cancer. Increased understanding of genomic architecture and achievement of innovative therapeutic strategies has prompted creation of a novel oncological model for the treatment of solid cancers. In this study, we systematically analyzed the transcriptome of breast cancer tissues to gain more in-depth knowledge of tumor biology. Gene coexpression relationships were studied in 206 samples from The Cancer Genome Atlas database, and nine coexpression modules were identified. After screening and analysis, we identified four important prognosis-related lncRNAs (HOTAIR, SNHG16, HCP5, and TINCR), and constructed a prognostic model, one (HCP5) of which has not previously been identified in the context of breast cancer. Importantly, an understanding of prognosis facilitates precise disease risk assessment and advances the selection of strategies for risk-adaptive management. These findings broaden the landscape of carcinogenic lncRNAs in breast cancer, providing insights into the biological significance and clinical application of lncRNAs in breast cancer.

Genome-wide identification of lncRNAs and mRNAs differentially expressed in non-functioning pituitary adenoma and construction of an lncRNA-mRNA co-expression network

The involvement of long non-coding RNAs (lncRNAs) during tumorigenesis is a recent emerging theme. Yet no systematic evaluation of lncRNAs has been previously reported for non-functioning pituitary adenoma (NFPA), a fairly common type of intracranial tumor. Here, we report the first genome-wide expression profile for lncRNAs and mRNAs in NFPA, using formalin-fixed and paraffin-embedded tissue specimens. Using microarray analyses, we identified 113 lncRNAs and 80 mRNAs differentially expressed in NFPA; this list includes lncRNAs previously implicated in a variety of cancers. Using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) we further confirmed differential expression in NFPA for ten of the 113 lncRNAs. Using these ten doubly confirmed lncRNAs, we constructed an lncRNA-mRNA co-expression network comprising of 130 specific lncRNA-mRNA co-expression relationships. In addition, we conducted GO and KEGG analyses for the 80 mRNAs differentially expressed in NFPA. Our microarray and qRT-PCR analyses provided a working list of lncRNAs that may be functionally relevant to NFPA tumorigenesis. Our co-expression network in turn connected these largely uncharacterized lncRNAs to specific mRNAs, whose roles we further elucidated via GO and KEGG analyses, thus providing specific, testable hypotheses for the functions of these lncRNAs. Together, our study laid the foundation for future investigation of the specific function and mechanism by which lncRNAs are involved in NFPA tumorigenesis.

Summary statement: We identified long non-coding RNAs and mRNAs differentially expressed in non-functioning pituitary adenomas via microarray analyses, and provided working hypotheses for how these RNAs may function via co-expression network analyses.

Association between genetic polymorphisms in long non-coding RNAs and pancreatic cancer risk

BACKGROUND

Long non-coding RNAs (lncRNAs) are emerging as candidate biomarkers of cancer, having regulatory functions in both oncogenic and tumor-suppressive pathways. Concerning pancreatic cancer (PC), deregulation of lncRNAs involved in tumor initiation, invasion, and metastasis seem to play a key role. However, data is scarce about regulatory mechanism of lncRNA expression.

OBJECTIVE

The aim of our study was to investigate the contribution of two lncRNAs polymorphisms (rs1561927 and rs4759313 of PVT1 and HOTAIR, respectively) in PC susceptibility.

METHODS

A case-control study was conducted analysing rs1561927 and rs4759313 polymorphisms using DNA collected in a population-based case-control study of pancreatic cancer (111 pancreatic ductal adenocarcinoma cases (PDAC), 56 pancreatic neuroendocrine tumor (PNET), and 125 healthy controls).

RESULTS

Regarding the PVT1 rs1561927 polymorphism the G allele was significantly overrepresented in both PDAC and PNET patients compared to the controls, while the presence of the HOTAIR rs4759314 G allele was found to be overrepresented in the PNET patients only compared to the controls. The PVT1 rs1561927 AG/GG genotypes were associated with poor overall survival in PDAC patients.

CONCLUSIONS

Our results suggested that polymorphisms of these two lncRNA polymorphisms implicated in pancreatic carcinogenesis. Further large-scale and functional studies are needed to confirm our results.

The regulatory roles of long noncoding RNAs in the biological behavior of pancreatic cancer

Long noncoding RNAs (lncRNAs) are a new class of regulators. LncRNAs are defined as endogenous transcribed RNA molecules with transcript length of >200 nt. Accumulating evidence has shown that lncRNAs are involved in many physiological processes such as cell cycle regulation, cell apoptosis and survival, cancer migration and metabolism. However, the biological and molecular mechanisms of lncRNAs in pancreatic cancer are still unclear. Recent studies have reported that many lncRNAs are dysregulated in pancreatic cancer and closely associated with tumorigenesis, diagnosis and prognosis. In this review, we described the regulation and functional role of lncRNAs and the potential underlying mechanism involved in pancreatic cancer, outlined the roles of lncRNA in pancreatic cancer, and discussed the potential possibility of lncRNAs as therapeutic targets in clinical practice. Moreover, the potential of lncRNAs used as sensitive biomarkers for diagnosis, prognosis and prediction of response to therapy in pancreatic cancer will also be discussed.

The prognostic potential of long noncoding RNA HOTAIR expression in human digestive system carcinomas: A meta-analysis

Homeobox transcript antisense intergenic RNA (HOTAIR), one of the well-known long noncoding RNAs (lncRNAs), plays an important role in initiation and development of various tumors. Elevated level of HOTAIR is associated with metastatic behavior of primary tumor and poor outcome in several cancers. Therefore, we conducted a meta-analysis to clearly measure the prognostic impact of HOTAIR in patients with digestive system carcinomas. Fourteen studies including 2,666 patients with five different type of digestive system cancers were selected to be entered in meta-analysis. Finding demonstrated that HOTAIR overexpression could predict unfavorable outcome in digestive system carcinomas (hazard ratio [HR] = 2.4, 95% confidence interval [CI]: 2.0-2.9; p < 0.001; fixed-effect model). In stratified analysis, increased level of HOTAIR predicted poor overall survival in gastric cancer (HR = 2.1, 95% CI: 1.6-2.9; p < 0.001), colorectal cancer (HR = 4.1, 95% CI: 1.6-10.2; p = 0.002), esophageal squamous cell carcinoma (HR = 2.3, 95% CI: 1.7-3.0; p < 0.001), and hepatocellular carcinoma (HR = 3.4, 95% CI: 1.9-6.1; p < 0.001). Our meta-analysis results clearly support the prognostic value of HOTAIR to predict unfavorable prognostic outcomes in diverse digestive system carcinomas.

The roles of lncRNA in hepatic fibrosis

Increasing evidence indicates that long non-coding RNAs (lncRNAs) regulate gene or protein expression; however, their function in the progression of hepatic fibrosis remains unclear. Hepatic fibrosis is a continuous wound-healing process caused by numerous chronic hepatic diseases, and the activation of hepatic stellate cells (HSCs) is generally considered to be a pivotal step in hepatic fibrosis. In the process of hepatic fibrosis, some lncRNAs regulates diverse cellular processes. Here are several examples: the lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and liver fibrosis-associated lncRNA1 (lnc-LFAR1) promote HSC activation in the progression of hepatic fibrosis via the transforming growth factor-β signaling pathway; the lncRNA HIF 1 alpha-antisense RNA 1 (HIF1A-AS1) and Maternally expressed gene 3 reduce HSC activation which are associated with DNA methylation; the lncRNA plasmacytoma variant translocation 1, Homeobox (HOX) transcript antisense RNA and MALAT1 promote HSC activation as competing endogenous RNAs (ceRNAs); the long intergenic non-coding RNA-p21 (lncRNA-p21) and Growth arrest-specific transcript 5 reduce HSC activation as ceRNAs. As we get to know more about the function of lncRNAs in hepatic fibrosis, more and more ideas for the molecular targeted therapy in hepatic fibrosis will be put forward.

Several genes involved in the JAK-STAT pathway may act as prognostic markers in pancreatic cancer identified by microarray data analysis

PURPOSE

This study aimed to identify the underlying mechanisms in pancreatic cancer (PC) carcinogenesis and those as potential prognostic biomarkers, which can also be served as new therapeutic targets of PC.

METHODS

Differentially expressed genes (DEGs) were identified between PC tumor tissues and adjacent normal tissue samples from a public GSE62452 dataset, followed by functional and pathway enrichment analysis. Then, protein-protein interaction (PPI) network was constructed and prognosis-related genes were screened based on genes in the PPI network, before which prognostic gene-related miRNA regulatory network was constructed. Functions of the prognostic gene in the network were enriched before which Kaplan-Meier plots were calculated for significant genes. Moreover, we predicted related drug molecules based on target genes in the miRNA regulatory network. Furthermore, another independent GSE60979 dataset was downloaded to validate the potentially significant genes.

RESULTS

In the GSE62452 dataset, 1017 significant DEGs were identified. Twenty-six important prognostic-related genes were found using multivariate Cox regression analysis. Through pathway enrichment analysis and miRNA regulatory analysis, we found that the 5 genes, such as Interleukin 22 Receptor Subunit Alpha 1 (IL22RA1), BCL2 Like 1 (BCL2L1), STAT1, MYC Proto-Oncogene (MYC), and Signal Transducer And Activator Of Transcription 2 (STAT2), involved in the Jak-STAT signaling pathway were significantly associated with prognosis. Moreover, the expression change of these 5 genes was further validated using another microarray dataset. Additionally, we identified camptothecin as an effective drug for PC.

CONCLUSION

IL22RA1, BCL2L1, STAT1, MYC, and STAT2 involved in the Jak-STAT signaling pathway may be significantly associated with prognosis of PC.

Role of Long Noncoding RNA 799 in the Metastasis of Cervical Cancer through Upregulation of TBL1XR1 Expression

Long noncoding RNAs (lncRNAs) are closely associated with the molecular mechanisms underlying cancer development, and it would be highly useful to study their expression and mechanisms in cervical cancer too. The current study investigated lncRNA799 expression in cervical cancer in order to determine its clinical importance in the progression of cervical cancer. lncRNA799 expression was studied in 218 cervical cancer samples. Expression of lncRNA799 was significantly higher in the cervical cancer tissue than in the adjacent normal tissue. Overexpression of lncRNA799 was found to have a significant correlation with FIGO stage, SCC-Ag level, and lymphatic metastasis, and it was also associated with poor survival. Ectopic expression of lncRNA799 promoted the metastasis of SiHa cells, whereas lncRNA799 knockdown had an inhibitory effect on metastasis. Western blot analysis demonstrated that lncRNA799 promotes the expression of transducing β-like protein 1-related protein (TBL1XR1), and that lncRNA799 and TBL1XR1 expression show strong correlation in cervical cancer. Moreover, lncRNA799 modulated the expression of TBL1XR1 by acting as a competitive endogenous RNA (ceRNA) for miR-454-3P. The results indicate that lncRNA799 could be used as a novel marker of cervical cancer prognosis. Thus, targeting the ceRNA network involving lncRNA799 could be a potential treatment strategy against cervical cancer.

Accurate prediction of protein-lncRNA interactions by diffusion and HeteSim features across heterogeneous network

Background

Identifying the interactions between proteins and long non-coding RNAs (lncRNAs) is of great importance to decipher the functional mechanisms of lncRNAs. However, current experimental techniques for detection of lncRNA-protein interactions are limited and inefficient. Many methods have been proposed to predict protein-lncRNA interactions, but few studies make use of the topological information of heterogenous biological networks associated with the lncRNAs.

Results

In this work, we propose a novel approach, PLIPCOM, using two groups of network features to detect protein-lncRNA interactions. In particular, diffusion features and HeteSim features are extracted from protein-lncRNA heterogenous network, and then combined to build the prediction model using the Gradient Tree Boosting (GTB) algorithm. Our study highlights that the topological features of the heterogeneous network are crucial for predicting protein-lncRNA interactions. The cross-validation experiments on the benchmark dataset show that PLIPCOM method substantially outperformed previous state-of-the-art approaches in predicting protein-lncRNA interactions. We also prove the robustness of the proposed method on three unbalanced data sets. Moreover, our case studies demonstrate that our method is effective and reliable in predicting the interactions between lncRNAs and proteins.

Availability

The source code and supporting files are publicly available at: http://denglab.org/PLIPCOM/.

lncRNA HOTAIR upregulates COX-2 expression to promote invasion and migration of nasopharyngeal carcinoma by interacting with miR-101

BACKGROUND

Nasopharyngeal carcinoma (NPC) is the most common type of head and neck cancers which is notable for its distinctive pattern of geographical distribution. HOTAIR has been reported to regulate nasopharyngeal carcinoma tumorigenesis and progression. However, the detailed mechanism underlying HOTAIR-promoted nasopharyngeal carcinoma remains not fully understood.

METHODS

We used RT-qPCR approach to examine genes expression and mRNA level. MTT assay and soft agar assay were used to detect cell growth rate in culture and under suspended condition, respectively. Besides, we employed wound healing assay and transwell invasion assay to determine migration and invasion ability of nasopharyngeal carcinoma cells. We predicted direct downstream targets of miR-101 by bioinformatic analysis, which was confirmed by dual luciferase reporter assay.

RESULTS

HOTAIR was upregulated in NPC tissues and cells. miR-101 inhibitor greatly enhanced HOTAIR knockdown-regulated cell proliferation, migration and invasion of CNE1 and CNE2 cells. miR-101 was shown to directly bind 3'-UTR of COX-2 and downregulate COX-2 expression. Finally, COX-2 overexpression was demonstrated to rescue the tumor phenotypes of nasopharyngeal carcinoma cells attenuated by HOTAIR knockdown or miR-101 mimic.

CONCLUSIONS

Here, we highlight the importance of HOTAIR/miR-101/COX-2 axis in progression of nasopharyngeal carcinoma cells. Our findings provide a novel mechanism for explaining HOTAIR-induced nasopharyngeal carcinoma and help developing the therapeutical strategies by targeting HOTAIR.

LncRNA HOTAIR/miR-613/c-met axis modulated epithelial-mesenchymal transition of retinoblastoma cells

Since lncRNAs could modulate neoplastic development by modulating downstream miRNAs and genes, this study was carried out to figure out the synthetic contribution of HOTAIR, miR-613 and c-met to viability, apoptosis and proliferation of retinoblastoma cells. Totally 276 retinoblastoma tissues and tumour-adjacent tissues were collected, and human retinoblastoma cell lines (ie, Y79, HXO-Rb44, SO-Rb50 and WERI-RB1) were also gathered. Moreover, transfections of pcDNA3.1-HOTAIR, si-HOTAIR, miR-613 mimic, miR-613 inhibitor, pcDNA3.1/c-met were performed to evaluate the influence of HOTAIR, miR-613 and c-met on viability, apoptosis and epithelial-mesenchymal transition (EMT) of retinoblastoma cells. Dual-luciferase reporter gene assay was also arranged to confirm the targeted relationship between HOTAIR and miR-613, as well as between miR-613 and c-met. Consequently, up-regulated HOTAIR and down-regulated miR-613 expressions displayed associations with poor survival status of retinoblastoma patients (P < 0.05). Besides, inhibited HOTAIR and promoted miR-613 elevated E-cadherin expression, yet decreased Snail and Vimentin expressions (P < 0.05). Simultaneously, cell proliferation and cell viability were also less-motivated (P < 0.05). Nonetheless, c-met prohibited the functioning of miR-613, resulting in promoted cell proliferation and viability, along with inhibited cell apoptosis (P < 0.05). Finally, HOTAIR was verified to directly target miR-613, and c-met was the direct target gene of miR-613 (P < 0.05). In conclusion, the role of lncRNA HOTAIR/miR-613/c-met signalling axis in modulating retinoblastoma cells' viability, apoptosis and expressions of EMT-specific proteins might provide evidences for developing appropriate diagnostic and treatment strategies for retinoblastoma.

Long noncoding RNA HOTAIR is upregulated in an aggressive subgroup of gastrointestinal stromal tumors (GIST) and mediates the establishment of gene-specific DNA methylation patterns

Aberrant alterations of DNA methylation are common events in oncogenesis. The origin of cancer-associated epigenetic defects is of interest for mechanistic understanding of malignant transformation and-in the long run-therapeutic modulation of DNA methylation in a locus-specific manner. Given the ability of certain long noncoding RNAs to operate as an interface between DNA and the epigenetic modification machinery which can interact with DNA methyltransferases, we hypothesized-considering HOTAIR as an example-that this transcript may contribute to gene specificity of DNA methylation. Using gastrointestinal stromal tumors (GISTs, n = 67) as a model, we confirmed upregulation of HOTAIR in tumors with high risk of recurrence and showed high abundance of the transcript in GIST cell lines. HOTAIR knockdown in GIST-T1 cells triggered transcriptional response of genes involved in the organization and disassembly of the extracellular matrix and, notably, induced global locus-specific alterations of DNA methylation patterns. Hypomethylation was induced at a total of 507 CpG sites, whereas 382 CpG dinucleotides underwent gain of methylation upon HOTAIR depletion. Importantly, orchestrated gain or loss of methylation at multiple individual CpG sites was shown for cancer-related DPP4, RASSF1, ALDH1A3, and other targets. Collectively, our data indicate that HOTAIR enables target specificity of DNA methylation in GIST and is capable of dual (hypo- and hypermethylation) regulation by a yet to be defined mechanism. The results further suggest the feasibility of manipulating DNA methylation in a targeted manner and are of interest in the context of epigenetic cancer therapy.

An integrated genomic analysis of anaplastic meningioma identifies prognostic molecular signatures

Anaplastic meningioma is a rare and aggressive brain tumor characterised by intractable recurrences and dismal outcomes. Here, we present an integrated analysis of the whole genome, transcriptome and methylation profiles of primary and recurrent anaplastic meningioma. A key finding was the delineation of distinct molecular subgroups that were associated with diametrically opposed survival outcomes. Relative to lower grade meningiomas, anaplastic tumors harbored frequent driver mutations in SWI/SNF complex genes, which were confined to the poor prognosis subgroup. Aggressive disease was further characterised by transcriptional evidence of increased PRC2 activity, stemness and epithelial-to-mesenchymal transition. Our analyses discern biologically distinct variants of anaplastic meningioma with prognostic and therapeutic significance.

Silence of long intergenic noncoding RNA HOTAIR ameliorates oxidative stress and inflammation response in ox-LDL-treated human macrophages by upregulating miR-330-5p

Evidence of the involvement of long noncoding RNAs (lncRNAs) in atherosclerosis is growing but still not well characterized. Here, we concentrated on the biological roles of lncRNA HOX transcription antisense RNA (HOTAIR) in atherosclerosis. In our study, we found that oxidized low-density lipoprotein (ox-LDL) induced human macrophages THP-1 cells apoptosis dose dependently and time dependently. Meanwhile, HOTAIR was significantly increased in THP-1 cells treated with ox-LDL. Then, HOTAIR was modulated by infection of LV-short hairpin RNA (shRNA) and LV-HOTAIR into THP-1 cells. As displayed, CD36, Oil Red O staining levels, total cholesterol, triglyceride levels and dil-ox-LDL uptake rate were greatly repressed by the silence of HOTAIR while triggered by overexpression of HOTAIR. Moreover, knockdown of HOTAIR suppressed reactive oxygen species, malondialdehyde levels, increased superoxide dismutase activity and cell apoptosis were also restrained. Reversely, overexpression of HOTAIR exhibited an opposite phenomenon. In addition, interleukin 6 (IL-6), IL-1β, cyclo-oxygenase 2, and tumor necrosis factor α protein levels were significantly depressed by LV-shRNA) of HOTAIR while increased by upregulation of HOTAIR in THP-1 cells. By carrying out bioinformatics analysis, miR-330-5p was predicted as a target of HOTAIR and the correlation between them was validated in our current study. MiR-330-5p was greatly decreased in THP-1 cells incubated with ox-LDL and overexpression of miR-330-5p was able to inhibit oxidative stress and inflammation process. Taken together, it was implied that HOTAIR contributed to atherosclerosis development by downregulating miR-330-5p in human macrophages.

lncRNA involvement in hepatocellular carcinoma metastasis and prognosis

Eukaryotic lncRNAs are RNA molecules defined to be greater than 200 bp in length that are not translated to a protein and operate through several mechanisms, including participating in chromatin remodeling and methylation, influencing the integrity and stability of proteins and complexes, or acting as a sponge for miRNA inhibition. A number of recent studies have concentrated on the relationship between long non-coding RNAs (lncRNAs) and cancer. Hepatocellular carcinoma (HCC) is the most prevalent histological type of liver tumors, accounting for about 80 % of the cases worldwide. Lack of proper molecular markers for diagnosis of HCC and treatment evaluation is a significant problem. Dysregulated expression of HCC-related lncRNAs such as MEG-3, MALAT1, HULC, HOTAIR, and H19 have been identified and closely related with tumorigenesis, metastasis, prognosis and diagnosis. In this review, we summarized recent highlighted functions and molecular mechanisms of the most extensively studied lncRNAs in the pathophysiology of hepatocellular carcinoma and their potential for serving as probable therapeutic targets.

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.

The lncRNA HOTAIR transcription is controlled by HNF4α-induced chromatin topology modulation

The expression of the long noncoding RNA HOTAIR (HOX Transcript Antisense Intergenic RNA) is largely deregulated in epithelial cancers and positively correlates with poor prognosis and progression of hepatocellular carcinoma and gastrointestinal cancers. Furthermore, functional studies revealed a pivotal role for HOTAIR in the epithelial-to-mesenchymal transition, as this RNA is causal for the repressive activity of the master factor SNAIL on epithelial genes. Despite the proven oncogenic role of HOTAIR, its transcriptional regulation is still poorly understood. Here hepatocyte nuclear factor 4-α (HNF4α), as inducer of epithelial differentiation, was demonstrated to directly repress HOTAIR transcription in the mesenchymal-to epithelial transition. Mechanistically, HNF4α was found to cause the release of a chromatin loop on HOTAIR regulatory elements thus exerting an enhancer-blocking activity.

Long non-coding RNA HOTAIR promotes tumorigenesis and forecasts a poor prognosis in cholangiocarcinoma

Cholangiocarcinoma (CCA) arising from the neoplastic transformation of cholangiocytes with increasing incidence in the worldwide. Unfortunately, a large amount of CCA patients lost their chance for surgery because it is hard to diagnose in the early stages. Long non-coding RNAs (lncRNAs) is closely associated with development and progression of various malignant tumors. Hox transcript antisense intergenic (HOTAIR), a negative prognostic factor for patients with gastric, liver and pancreatic carcinoma. Its transcription levels and functional roles in CCA is still unknown. Therefore, we aimed to explore the effect of HOTAIR in CCA including cell proliferation, apoptosis, migration, invasion and epithelial-to-mesenchymal transition (EMT). The results showed that HOTAIR was highly expressed both in CCA tissue samples and cell lines compared with corresponding normal bile duct tissues and Human intrahepatic biliary epithelial cells (HIBEC). Its overexpression was closely correlated with Tumor size, TNM stage and postoperative recurrence in CCA patients. Moreover, up-regulation of HOTAIR has correlation with prognosis in CCA patients. Knockdown of HOTAIR by siRNAs significantly decreased the migration and invasion but increased apoptosis of CCA cells in vitro. Overall, our study revealed that HOTAIR may play as a new potential therapeutic target and forecast poor prognosis for this fatal disease.

Long non-coding RNA LINC00346, LINC00578, LINC00673, LINC00671, LINC00261, and SNHG9 are novel prognostic markers for pancreatic cancer

Pancreatic cancer (PC) is a devastating human disease with aggressive course and extremely poor prognosis. Long non-coding RNAs (lncRNAs) have been studied to serve as a critical role in pancreatic development and progression. However, little is known about its expression pattern, biological function in PC. In our study, we measured the expression levels of six lncRNAs (LINC00346, LINC00578, LINC00673, LINC00671, LINC00261, and SNHG9) in PC tissues and serums. The results showed that LINC00346, LINC00578, and LINC00673 were highly expressed, whereas LINC00671, LINC00261, and SNHG9 were lowly expressed in PC tissues and serums, and their expression levels were correlated with clinical stages. Results from receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) of six lncRNAs was 0.7073, 0.7837, 0.6093, 0.6057, 0.5712, and 0.5983, respectively. Survival analysis indicated that patients with high expression of LINC00346, LINC00578, or LINC00673 had significantly lower survival rate, while patients with high expression of LINC00671, LINC00261, and SNHG9 had significantly higher survival rate. In addition, we also found that silence of LINC00346, LINC00578 and LINC00673 inhibited PC cell proliferation, and silence of LINC00671, LINC00261, and SNHG9 promoted PC cell proliferation. Therefore, we suggested that LINC00346, LINC00578, LINC00673, LINC00671, LINC00261, and SNHG9 may be novel prognostic markers for PC.

The Use of Biomarkers in Early Diagnostics of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid malignancies with increasing incidence. The poor prognosis is due to the aggressive nature of the tumor, late detection, and the resistance to chemotherapy and radiotherapy. A radical surgery procedure is the only treatment that has been shown to improve the 5-year survival rate to 20-25%. However, the majority of patients (80-85%) are diagnosed with locally advanced or metastatic disease and just 15-20% patients are diagnosed in an early stage allowing them to undergo the potentially curative surgical resection. The early detection of PDAC without the use of invasive methods is challenging and discovery of a cost-effective biomarker with high specificity and sensitivity could significantly improve the treatment and survival in these patients. In this review, we summarize current and newly examined biomarkers in early PDAC detection.

Downregulation of Long Noncoding RNA HOTAIR and EZH2 Induces Apoptosis and Inhibits Proliferation, Invasion, and Migration of Human Breast Cancer Cells

BACKGROUND

The long noncoding RNA HOTAIR (HOX transcript antisense intergenic RNA) has been reported to be a biomarker for various malignant tumors; however, its involvement in breast cancer is not fully understood. The aim of this study was to investigate the effects involved with long noncoding RNA HOTAIR and EZH2 (enhancer of zeste homologue 2) on the processes of proliferation, invasion, migration, and apoptosis of breast cancer cells.

MATERIALS AND METHODS

The expressions of HOTAIR and EZH2 in both normal human mammary epithelial cell (HBL-100) and breast cancer cell lines (MCF-7, MDA-MB-231, and SKBR-3) were detected by means of reverse transcription-quantitative polymerase chain reaction. The MCF-7 cells that exhibited the highest HOTAIR expressions were selected for further studies and divided into the control, negative control, and small interfering RNA-HOTAIR groups. The proliferation, invasion, migration, and apoptosis of breast cancer cells were evaluated by MTT assay, Scratch test, Transwell assay, and flow cytometry, respectively. The combination of HOTAIR with EZH2 and PTEN was predicted by bioinformation, with a dual-luciferase reporter gene assay providing further verification.

RESULTS

Initially, lower expressions of HOTAIR and EZH2 in the normal human mammary epithelial cells, while higher expressions in the breast cancer cells of MCF-7, MDA-MB-231, and SKBR-3 were detected. In addition, the downregulation of HOTAIR or silencing of EZH2 was revealed to repress the proliferation, invasion, and migration, while acting to promote the apoptosis of the breast cancer cells. Furthermore, HOTAIR could bind specifically to EZH2 and PTEN, highlighting the capability of HOTAIR to inhibit the expression of PTEN by recruiting EZH2 in breast cancer, while the TCGA database demonstrated the expressions of PTEN were lower in breast cancer cells.

CONCLUSIONS

The study suggests the higher expressions of HOTAIR and EZH2 among three breast cancer cells. Furthermore, the downregulation of HOTAIR or silencing of EZH2 was noted to inhibit the proliferation, invasion, and migration of breast cancer cells, while promoting their apoptosis.