Long non-coding RNA UCA1 promotes breast tumor growth by suppression of p27 (Kip1)

The prognostic value and mechanisms of lncRNA UCA1 in human cancer

Long noncoding RNAs (lncRNAs), longer than 200 nucleotides in length, play important roles in the development and progression of various cancers. An increasing number of studies have revealed that lncRNAs function as potential oncogenes or tumor suppressors to influence biological processes, such as cell growth, invasion, migration and apoptosis. Urothelial carcinoma associated 1 (UCA1), an oncogenic lncRNA, was first found in bladder cancer and highly expressed in multiple cancers, including gastric cancer, colorectal cancer, lung cancer and breast cancer. UCA1 promotes tumorigenesis mainly via binding to tumor-suppressive microRNAs (miRNAs), activating several pivotal signaling pathways and alteration of epigenetic and transcriptional regulation. In addition, high expression of UCA1 is related to poor clinicopathological features especially for shorter overall survival, suggesting that UCA1 might be regarded as a prognosis biomarker in human cancers. In the present review, we summarized current studies on UCA1 to explore its prognostic value and underlying regulation mechanisms in the development of multiple cancers in order to provide a glimmer of hope for the prevention and treatment of malignant tumors.

Crosstalk between the lncRNA UCA1 and microRNAs in cancer

Long non-coding RNAs (lncRNAs) are a major subset of highly conserved non-coding RNAs (ncRNAs) that consist of at least 200 nucleotides and have limited protein-coding potential. Cumulative data have shown that lncRNAs are deregulated in many types of cancer and may control pathophysiological processes of cancer at various levels, including transcription, post-transcription and translation. Recently, lncRNAs have been demonstrated to interact with microRNAs (miRNAs), another major subset of ncRNAs, which regulate physiological and pathological processes by inhibiting target mRNA translation or promoting mRNA degradation. The lncRNA urothelial carcinoma-associated 1 (UCA1) has recently gained much attention as it is overexpressed in many types of cancer and is involved in carcinogenesis. Here, we review the crosstalk between UCA1 and miRNAs during the pathogenesis of cancer, with a focus on cancer-cell proliferation, invasion, drug resistance, and metabolism.

Long non-coding RNA XIST predicting advanced clinical parameters in cancer: A Meta-Analysis and case series study in a single institution

Dysregulated expression of long non-coding RNA X-inactive specific transcript (lncRNA-XIST) has been indicated in various cancer types. In the present study, a meta-analysis was conducted to evaluate the potential role of lncRNA-XIST in predicting the clinicopathological parameters of patients with cancer. Eligible studies were obtained through a systematic search of PubMed, Web of Science, Embase and the Cochrane Library, of articles published prior to January 2019. The combined odds ratio and 95% confidence interval were calculated to determine the association between lncRNA-XIST expression and patient outcome. In addition, 45 pairs of osteosarcoma (OS) tissues and adjacent healthy tissues from a single institution were analyzed for the expression of lncRNA-XIST, and its association with clinicopathological features; ultimately, a total of 1,869 cancer patients from 25 studies were assessed. The results demonstrated that high expression levels of lncRNA-XIST were significantly associated with lymphatic metastasis, larger tumor size, advanced cancer stage and distant metastasis. However, sex was not associated with lncRNA-XIST expression level. In the OS patient cohort, it was demonstrated that lncRNA-XIST was highly expressed in OS tissues, which negatively correlated with patient prognosis. The present study indicated that lncRNA-XIST may serve as a potential biomarker for advanced clinical parameters in human cancer.

The Regulatory Roles of Long Noncoding RNAs in Acute Myeloid Leukemia

In this post-genomic era, long noncoding RNAs (lncRNAs) are rapidly gaining recognition for their crucial roles across diverse biological processes and contexts. The human blood system is no exception, where dozens of lncRNAs have been established as regulators of normal and/or malignant hematopoiesis, and where ongoing works continue to uncover novel lncRNA functions. Our review focuses on lncRNAs that are involved in the pathogenesis of acute myeloid leukemia (AML) and the mechanisms through which they control gene expression in this disease context. We also comment on genome-wide sequencing or profiling studies that have implicated large sets of lncRNAs in AML pathophysiology.

WITHDRAWN: Long non-coding RNA UCA1 regulates tumor growth by impairing let-7e-dependent HMGA2 repression in bladder cancer

Ahead of Print article withdrawn by publisher.

Suppression of the long non-coding RNA MALAT-1 impairs the growth and migration of human tongue squamous cell carcinoma SCC4 cells

INTRODUCTION

Aberrant expression of long non-coding RNAs (lncRNAs) is associated with metastasis and poor prognosis in patients with various cancer types. However, few studies have assessed lncRNAs in oral squamous cell carcinoma (OSCC). This study aimed to investigate the expression and impact of lncRNAs in OSCC.

MATERIAL AND METHODS

Real-time PCR analysis was used to examine the expression of four lncRNAs, MALAT-1, UCA1, BC200 and SRA, in 14 OSCC and adjacent normal tissue pairs. The impact of MALAT-1 suppression by siRNA on the proliferation, apoptosis, anchorage-independent growth and migration of the human tongue carcinoma cell line SSC4 was also determined.

RESULTS

MALAT-1 levels were significantly higher in the OSCC tissue than in the normal tissues (p < 0.004); no significant differences in UCA1, BC200 or SRA RNA levels were observed. Knockdown of MALAT-1 by siRNA significantly suppressed proliferation of SSC4 cells (p < 0.004) and enhanced their apoptosis (p < 0.001). In addition, siRNA-mediated suppression of MALAT-1 inhibited SSC4 cell colony formation (p < 0.001) and migration (p < 0.004).

CONCLUSIONS

Elevated expression of MALAT-1 in OSCC may play a role in tumorigenesis and/or metastasis. Further studies are necessary to identify the mechanism by which MALAT-1 influences SCC4 growth and migration and validate its increased expression in OSCC patients.

Long noncoding RNA LINC00488 functions as a ceRNA to regulate hepatocellular carcinoma cell growth and angiogenesis through miR-330-5

BACKGROUND

Long non-coding RNAs (lncRNAs) recently have been identified as influential indicators in a variety of malignancies. Hence, the aim of the present study was to identify a functional lncRNA and its associated effects on hepatocellular carcinoma (HCC) in terms of cellular growth and a ngiogenesis.

METHODS AND RESULTS

Microarray-based analysis revealed a possible regulatory mechanism involving LINC00488, microRNA-330-5p (miR-330-5p) and talin-1 (TLN1) in HCC. Targetscan and RNA22 online tools predicted the relationship among LINC00488, miR-330-5p and TLN1, which were further validated by dual luciferase reporter gene assay, RNA pull-down and RIP. To evaluate the effects of LINC00488 and miR-330-5p on the cellular process of HCC, we performed a series of in vitro and in vivo experiments, with the expression of LINC00488, miR-330-5p, and TLN1 altered by delivering plasmids into Hep3B cell line. The obtained results demonstrated that cells with siRNA-mediated depletion of LINC00488 or restoration of miR-330-5p displayed suppressed abilities of in vitro proliferation as well as of in vivo tumor growth and angiogenesis, while in vitro apoptosis was notably induced.

CONCLUSION

The fundamental findings of the present study collectively propose that lncRNA LINC00488 can competitively sponge miR-330-5p to regulate TLN1 in relation to the cell growth and angiogenesis in HCC.

[Long noncoding RNA UFC1 promotes metastasis and invasion of hepatocellular carcinoma cells in vitro via GSK-3β/β-catenin axis]

OBJECTIVE

To explore the role of Long noncoding RNA UFC1 (lincRNA-UFC1) in modulating the metastasis and invasion of hepatocellular carcinoma (HCC) cells and the underlying mechanism.

METHODS

Human HCC cell line Huh7 was infected with the lentiviral vector carrying lincRNA-UFC1 to obtain a cell line with lincRNA-UFC1 overexpression. A short hairpin RNA (shRNA) targeting lincRNA-UFC1 was delivered in human HCC BEL-7402 cells via a lentiviral vector to obtain a cell line with lincRNA-UFC1 knockdown. Expression levels of lincRNA-UFC1 in the two HCC cell lines were detected using real-time PCR, and the changes in the cell invasion and migration in response to lincRNA-UFC1 overexpression or knockdown were analyzed using Transwell and wound-healing assays. The expressions of GSK-3β/β-catenin-related proteins in the cells were detected with Western blotting. XAV-939, a GSK-3β/β-catenin inhibitor, was used for assessing the impact of lincRNAUFC1 overexpression on the invasion and migration of the HCC cells through Transwell and wound-healing assays.

RESULTS

Overexpression of lincRNA-UFC1 significantly promoted the invasion and migration of Huh7 cells as compared with the control cells (P &lt; 0.001), while lincRNA-UFC1 knockdown obviously suppressed the invasion and migration of BEL-7402 cells (P &lt; 0.001). The results of Western blotting showed that the expressions of proteins associated with the cell invasion and migration, namely β-catenin and P-GSK-3β, were significantly upregulated in response to lincRNA-UFC1 overexpression, and were obviously lowered after lincRNA-UFC1 knockdown. Treatment of the cells with XAV-939 significantly reversed the effect of lincRNA-UFC1 overexpression on the cell invasion and migration (P &lt; 0.001).

CONCLUSIONS

lincRNA-UFC1 overexpresison promotes cell invasion and migration through the GSK-3β/β-catenin axis in HCC cells in vitro.

Matrix Hyaluronan-CD44 Interaction Activates MicroRNA and LncRNA Signaling Associated With Chemoresistance, Invasion, and Tumor Progression

Tumor malignancies involve cancer cell growth, issue invasion, metastasis and often drug resistance. A great deal of effort has been placed on searching for unique molecule(s) overexpressed in cancer cells that correlate(s) with tumor cell-specific behaviors. Hyaluronan (HA), one of the major ECM (extracellular matrix) components have been identified as a physiological ligand for surface CD44 isoforms which are frequently overexpressed in malignant tumor cells during cancer progression. The binding interaction between HA and CD44 isoforms often stimulates aberrant cellular signaling processes and appears to be responsible for the induction of multiple oncogenic events required for cancer-specific phenotypes and behaviors. In recent years, both microRNAs (miRNAs) (with ~20–25 nucleotides) and long non-coding RNAs (lncRNAs) (with ~200 nucleotides) have been found to be abnormally expressed in cancer cells and actively participate in numerous oncogenic signaling events needed for tumor cell-specific functions. In this review, I plan to place a special emphasis on HA/CD44-induced signaling pathways and the presence of several novel miRNAs (e.g., miR-10b/miR-302/miR-21) and lncRNAs (e.g., UCA1) together with their target functions (e.g., tumor cell migration, invasion, and chemoresistance) during cancer development and progression. I believe that important information can be obtained from these studies on HA/CD44-activated miRNAs and lncRNA that may be very valuable for the future development of innovative therapeutic drugs for the treatment of matrix HA/CD44-mediated cancers.

Computational Analysis of lncRNA Function in Cancer

Long noncoding RNAs (lncRNAs) have been shown to play crucial roles in cancer biology. With the help of computational analysis illustrated here, the joint effects of lncRNAs and clinical variables can be quantified in a Cox model on cancer recurrence. Of importance, the predictive accuracy was then validated with the prognostic scores computed based on the suggested model. Further investigation of these potential lncRNAs would provide useful insights following the study of the mechanisms underlying the differential expression of these lncRNAs in association with and possibly contributing to cancer recurrence. Ultimately, the expanding knowledge of the function of lncRNAs curated by computational analysis will suggest new targets for cancer treatment.

The Role of lncRNAs in the Distant Metastasis of Breast Cancer

Breast cancer (BC) remains the most frequently diagnosed cancer worldwide. Among breast cancer patients, distant metastasis and invasion is the leading cause of BC related death. Recently, long non-coding RNAs (lncRNAs), which used to be considered a genetic byproduct (owing to their unknown biological function), have been reported to be highly implicated in the development and progression of BC. In this review, we produce a summary of the functions and mechanisms of lncRNAs implicated in the different distant metastases of BC. The functions of lncRNAs have been divided into two types: oncogenic type and tumor suppressor. Furthermore, the majority of them exert their roles through the regulation of invasion, migration, epithelial-mesenchymal transition (EMT), and the metastasis process. In the final part, we briefly addressed future research prospects of lncRNAs, especially the testing methods through which to detect lncRNAs in the clinical work, and introduced several different tools with which to detect lncRNAs more conveniently. Although lncRNA research is still in the initial stages, it is a promising prognosticator and a novel therapeutic target for BC metastasis, which requires more research in the future.

Long non-coding RNAs in Oral squamous cell carcinoma: biologic function, mechanisms and clinical implications

There is growing evidence that regions of the genome that cannot encode proteins play an important role in diseases. These regions are usually transcribed into long non-coding RNAs (lncRNAs). LncRNAs, little or no coding potential, are defined as capped transcripts longer than 200 nucleotides. New sequencing technologies have shown that a large number of aberrantly expressed lncRNAs are associated with multiple cancer types and indicated they have emerged as an important class of pervasive genes during the development and progression of cancer. However, the underlying mechanism in cancer is still unknown. Therefore, it is necessary to elucidate the lncRNA function. Notably, many lncRNAs dysregulation are associated with Oral squamous cell carcinoma (OSCC) and affect various aspects of cellular homeostasis, including proliferation, survival, migration or genomic stability. This review expounds the up- or down-regulation of lncRNAs in OSCC and the molecular mechanisms by which lncRNAs perform their function in the malignant cell. Finally, the potential of lncRNAs as non-invasive biomarkers for OSCC diagnosis are also described. LncRNAs hold promise as prospective novel therapeutic targets, but more research is needed to gain a better understanding of their biologic function.

KLF5 regulated lncRNA RP1 promotes the growth and metastasis of breast cancer via repressing p27kip1 translation

Increasing evidence suggest that lncRNAs (long noncoding RNAs) play important roles in human cancer. Breast cancer is a heterogeneous disease and the potential involvement of lncRNAs in breast cancer remains unexplored. In this study, we characterized a novel lncRNA, RP1-5O6.5 (termed as RP1). We found that RP1 was highly expressed in breast cancer and predicted poor prognosis of breast cancer patients. Gain-of-function and loss-of-function assays showed that RP1 promoted the proliferation and metastasis of breast cancer cells in vitro and in vivo. Mechanistically, RP1 maintained the EMT and stemness states of breast cancer cells via repressing p27kip1 protein expression. RP1 combined with the complex p-4E-BP1/eIF4E to prevent eIF4E from interacting with eIF4G, therefore attenuating the translational efficiency of p27kip1 mRNA. Furthermore, we found that p27kip1 evidently downregulated Snail1 but not ZEB1 to inhibit invasion of breast cancer cells. Kruppel-like factor 5 (KLF5) was positively correlated with RP1 in breast cancer tissues. Moreover, we demonstrated that KLF5 recruited p300 to the RP1 promoter to enhance RP1 expression. Taken together, our findings demonstrated that KLF5-regulated RP1 plays an oncogenic role in breast cancer by suppressing p27kip1, providing support for the clinical investigation of therapeutic approaches focusing on RP1.

The long noncoding RNA AK002107 negatively modulates miR-140-5p and targets TGFBR1 to induce epithelial-mesenchymal transition in hepatocellular carcinoma

The abnormal expression of long noncoding RNAs (lncRNAs) is associated with human carcinoma. The present study aimed to investigate the mechanisms underlying the function of lncRNA AK002107 in the progression of hepatocellular carcinoma (HCC). The differential expression of lncRNAs between HCC and paired nontumor tissues was identified using microarrays, and the correlation between the expression of lncRNA AK002107 and the clinical prognosis of HCC was analyzed. We investigated the role of lncRNA AK002107 in HCC tumor biology in vitro using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT), colony formation, and Matrigel invasion assays and in vivo by assessing the growth of xenografted HCC tumors. The potential microRNAs that interact with lncRNA AK002107 were identified using online tools and were verified using PCR and luciferase reporter assay. The levels of TGFBR1, E-cadherin, and vimentin were determined using western blot assays. We then further investigated the correlation between expression of lncRNA AK002107 with miR-140-5p and TGFBR1 expression in HCC tissues. The expression of lncRNA AK002107 is frequently upregulated in HCC samples and cell lines. Patients with HCC who have elevated lncRNA AK002107 expression exhibit poorer overall survival and disease-free survival. Silencing lncRNA AK002107 expression significantly inhibited HCC cell proliferation, colony formation, and invasion both in vitro and in vivo. Furthermore, lncRNA AK002107 directly binds to miR-140-5p and significantly inhibits miR-140-5p expression. The functions of lncRNA AK002107 in cell growth and tumor invasion are mediated via miR-140-5p. lncRNA AK002107 upregulated TGFBR1 expression and then induced epithelial-mesenchymal transition (EMT) by inhibiting miR-140-5p expression. The expression of lncRNA AK002107 inversely correlated with miR-140-5p expression and positively correlated with TGFBR1 expression in HCC tissues. In summary, lncRNA AK002107 functions as an oncogene in tumors by inhibiting miR-140-5p, targeting TGFBR1, and then inducing EMT. The lncRNA AK002107/miR-140-5p/TGFBR1/EMT regulatory network may be a valuable target for the development of novel diagnostic and treatment methods for HCC.

Human transposons are an abundant supply of transcription factor binding sites and promoter activities in breast cancer cell lines

Background

Transposable elements (TE) are commonly regarded as “junk DNA” with no apparent regulatory roles in the human genome. However, a growing body of evidence demonstrates that some TEs exhibit regulatory activities in a range of biological pathways and diseases, with notable examples in bile metabolism and innate immunity. TEs are typically suppressed by epigenetic modifications in healthy somatic tissues, which prevents both undesirable effects of insertional mutagenesis, and also unwanted gene activation. Interestingly, TEs are widely reported to be dysregulated in epithelial cancers, and while much attention has been paid to their effects on genome instability, relatively little has been reported on their effects on gene regulation. Here, we investigated the contribution of TEs to the transcriptional regulation in breast cancer cell lines.

Results

We found that a subset of TE subfamilies were enriched in oncogenic transcription factor binding sites and also harboured histone marks associated with active transcription, raising the possibility of these subfamilies playing a broad role in breast cancer transcriptional regulation. To directly assess promoter activity in triple negative breast cancer cell lines, we identified four breast cancer-associated genes with putative TE-derived promoters. TE deletion confirmed a contribution to promoter activity in all cases, and for two examples the promoter activity was almost completely contained within the TE.

Conclusions

Our findings demonstrate that TEs provide abundant oncogenic transcription factor binding sites in breast cancer and that individual TEs contain substantial promoter activity. Our findings provide further evidence for transcriptional regulation of human genes through TE exaptation by demonstrating the regulatory potential of TEs in multiple breast cancer cell lines.

Electronic supplementary material

The online version of this article (10.1186/s13100-019-0158-3) contains supplementary material, which is available to authorized users.

Investigating the diagnostic performance of HOTTIP, PVT1, and UCA1 long noncoding RNAs as a predictive panel for the screening of colorectal cancer patients with lymph node metastasis

Like other noncoding RNAs (ncRNAs), dysregulation of long ncRNAs (lncRNAs) has been associated with various clinicopathological features of colorectal cancer (CRC) patients such as lymph node metastasis (LNM). Recently, three aberrant expressed oncogenic lncRNA (onco-lncRNAs), including HOXA transcript at the distal tip (HOTTIP), plasmacytoma variant translocation 1 (PVT1), and urothelial carcinoma associated 1 (UCA1) have been reported in LNM. Herein, we compared the diagnostic performance of these lncRNAs as individual biomarkers and as a discriminating panel between LNM CRC patients, nonmetastatic lymph nodes (NLN) and normal healthy subjects. The lncRNAs expression level was measured by quantitative real-time PCR and analyzed by the Mann-Whitney U test. The receiver operating characteristic (ROC) curve analysis was applied to evaluate the diagnostic power. The Kaplan-Meier survival analysis was performed to outline the overall survival (OS) of CRC patients with an abnormal level of lncRNAs. The area under the ROC curve (AUC) of the overexpressed HOTTIP (0.7817; 95% CI, 0.6809-0.8824), PVT1 (0.8559; 95% CI, 0.7737-0.9382), and UCA1 (0.8135; 95% CI, 0.722-0.9051) introduced them as individual CRC biomarkers. As a predictive panel, the AUC values of the HOTTIP, PVT1, and UCA1 for training set were 0.9256 (95% CI, 0.8634-0.9879; all CRCs), 0.8708 (95% CI, 0.7709-0.9378; NLN) and 0.9804 (95% CI, 0.9585-0.9998; LNM), and for validation set were 0.9286 (95% CI, 0.8752-0.9820; all CRCs), 0.8911 (95% CI, 0.8238-0.9585; NLN), and 0.9833 (95% CI, 0.9642-1.002; LNM), respectively. Also, HOTTIP/PVT1/UCA1 panel dysregulation had a marked correlation with patient's OS in training set (logrank test P = 0.0121; hazard ratio [HR], 0.1225; 95% confidence interval [CI], 0.02376-0.6312), and in validation set (logrank test P < 0.0001, HR, 0.2003; 95% CI, 0.08942-0.4486). These data showed that the combination of HOTTIP, PVT1, and UCA1 as a predictive panel, has a better diagnostic performance than each of these lncRNAs individually, and could be used for the screening of patients with advanced CRC.

Regulatory roles of long noncoding RNAs implicated in cancer hallmarks

Cancer cells acquire numerous biological properties (designated "cancer hallmarks"), such as cell survival and energy metabolism, that facilitate tumor growth and metastatic dissemination during development. To date, eight hallmarks of cancer have been identified that provide a logical framework for understanding the remarkable diversity of neoplastic diseases, as proposed by Douglas Hanahan and Robert A. Weinberg. Long noncoding RNAs (lncRNAs), a category of transcripts widely demonstrated to exert significant regulatory effects on biological processes, have attracted considerable research attention due to their association with the occurrence and development of cancer. The mechanisms by which lncRNAs exert their functions require elucidation to optimize their potential utility as alternative biomarkers and therapeutic targets during tumor occurrence and progression. In this review, we have discussed recent research progress on lncRNAs involved in various cancer hallmarks and their related mechanisms of action, with a view to providing an updated picture of their immense therapeutic potential in the fight against cancer.

LncRNA UCA1/miR-143 miR-216b/HK2/MAPK signaling pathway is involved in the regulation of endothelial cell proliferation via the modulation of glycolysis in melanoma

Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs/miRs) are noncoding RNAs that function as regulators of tumor suppressors and oncogenes. The aim of the present study was to investigate the potential mechanism associated with the involvement of urothelial cancer associated 1 (UCA1) in melanoma. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed in order to determine the expression levels of UCA1, miR-143, miR-216b, and hexokinase 2 (HK2) in the melanoma and control groups, as well as the influence of UCA1, miR-143, and miR-216b on the expression of HK2, and the effect of lactate and UCA1 on the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK). Bioinformatics algorithm analysis and a luciferase assay were performed in order to predict miRNA targets. In addition, an MTT assay was performed in order to determine the effect of lactate and UCA1 expression on cell proliferation. A total of 39 participants, consisting of 18 patients with melanoma and 21 healthy control subjects, were included in the present study. The present study demonstrated that the expression levels of UCA1 mRNA, and HK2 mRNA and protein were enhanced in patients with melanoma compared with healthy controls; whereas the expression levels of miR-143 and miR-216b mRNA were suppressed in patients with melanoma compared with healthy controls. Furthermore, it was revealed that UCA1 negatively modulated the expression of miR-143 and miR-216b, and that miR-143 and miR-216b directly targeted the HK2 protein by binding to the HK2 3′ untranslated region (UTR). In addition, it was demonstrated that miR-143 and miR-216 suppressed the luciferase activity exhibited by wild-type HK2 3′-UTR. Furthermore, it was revealed that transfection with UCA1 small interfering RNA, and miR-143 and miR-216b mimics markedly suppressed HK2 mRNA and protein expression levels as well as lactate levels in human umbilical vein endothelial cells; however, O2 consumption was revealed to be enhanced post transfection. By contrast, transfection with UCA1 enhanced HK2 mRNA and protein expression levels as well as lactate production; however, O2 consumption was revealed to be suppressed post transfection. Lactate-induced phosphorylation of p38 MAPK was revealed to occur in a concentration-dependent manner, and UCA1 enhanced the phosphorylation level of p38 MAPK via the inhibition of miR-143 and miR-216b expression. Lactate and UCA1 were demonstrated to enhance cell proliferation. In conclusion, the present study demonstrated that the lncRNA UCA1/miR-143 miR-216b/HK2/lactic acid/MAPK axis may be involved in the pathogenesis of melanoma via the modulation of endothelial cells, and thus, lncRNA UCA1 may serve as a potential therapeutic target for melanoma treatment.

The UCA1/KRAS axis promotes human pancreatic ductal adenocarcinoma stem cell properties and tumor growth

Emerging evidence indicates that the long noncoding RNA UCA1 is upregulated in multiple cancers, including pancreatic ductal adenocarcinoma (PDAC), and plays a critical role in various complex biological processes. However, the functional roles of UCA1 in PDAC remain to be clarified. In the current study, we showed that UCA1 significantly promoted cell proliferation and tumor growth both in vitro and in vivo, and enhanced stemness maintenance of PDAC cell lines. Moreover, we found that UCA1 overexpression increased the activity and expression of oncogenic KRAS. Mechanistically, upregulated UCA1 increased phospho-KRAS protein levels by interacting with hnRNPA2B1, and KRAS facilitated high cytoplasmic accumulation of hnRNPA2B1. Additionally, we identified that UCA1 functioned as a competing endogenous RNA (ceRNA) to increase the expression of KRAS via sponging miR-590-3p, and in turn, KRAS promoted UCA1 expression. Collectively, these findings suggest that the UCA1-KRAS axis plays a crucial role in PDAC progression and that UCA1 may serve as a target for new PDAC therapies.

Comprehensive characterisation of compartment-specific long non-coding RNAs associated with pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDA) is a highly metastatic disease with limited therapeutic options. Genome and transcriptome analyses have identified signalling pathways and cancer driver genes with implications in patient stratification and targeted therapy. However, these analyses were performed in bulk samples and focused on coding genes, which represent a small fraction of the genome.

DESIGN

We developed a computational framework to reconstruct the non-coding transcriptome from cross-sectional RNA-Seq, integrating somatic copy number alterations (SCNA), common germline variants associated to PDA risk and clinical outcome. We validated the results in an independent cohort of paired epithelial and stromal RNA-Seq derived from laser capture microdissected human pancreatic tumours, allowing us to annotate the compartment specificity of their expression. We employed systems and experimental biology approaches to interrogate the function of epithelial long non-coding RNAs (lncRNAs) associated with genetic traits and clinical outcome in PDA.

RESULTS

We generated a catalogue of PDA-associated lncRNAs. We showed that lncRNAs define molecular subtypes with biological and clinical significance. We identified lncRNAs in genomic regions with SCNA and single nucleotide polymorphisms associated with lifetime risk of PDA and associated with clinical outcome using genomic and clinical data in PDA. Systems biology and experimental functional analysis of two epithelial lncRNAs (LINC00673 and FAM83H-AS1) suggest they regulate the transcriptional profile of pancreatic tumour samples and PDA cell lines.

CONCLUSIONS

Our findings indicate that lncRNAs are associated with genetic marks of pancreatic cancer risk, contribute to the transcriptional regulation of neoplastic cells and provide an important resource to design functional studies of lncRNAs in PDA.

Long noncoding RNA UCA1 promotes osteosarcoma metastasis through CREB1-mediated epithelial-mesenchymal transition and activating PI3K/AKT/mTOR pathway

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UCA1 is upregulated in both osteosarcoma tissues and cell lines.

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UCA1 promotes osteosarcoma metastasis both in vitro and in vivo.

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UCA1 increased CREB1 expression by functioning as a ceRNA of CREB1 against miR-582.

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The pro-metastasis role of UCA1 is achieved by promoting EMT.

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UCA1 enhances EMT through CREB1-mediated the PI3K/Akt/mTOR pathway.

Increasing evidences have demonstrated that Long noncoding RNAs (lncRNAs) are key regulatory RNAs that participate in multiple biological processes. LncRNA urothelial carcinoma-associated 1 (UCA1) is a newly identified lncRNA and functions as a regulator of growth in several cancers. However, the biological function and molecular mechanism of UCA1 in the metastasis of osteosarcoma remain unclear. In this study, we firstly found UCA1 is upregulated in both osteosarcoma tissues and cell lines, and increased UCA1 is associated with higher tumor stage, larger tumor size and poorer prognosis. Then for the first time, we demonstrated that UCA1 promotes the invasion and metastasis of osteosarcoma both in vitro and in vivo. Further mechanistic investigation showed that UCA1 directly interactes with miR-582 and suppresses its expression. Moreover, UCA1 increases CREB1 expression by functioning as a ceRNA against miR-582, thus promoting the EMT process via CREB1-mediated PI3K/AKT/mTOR pathway and finally leading to osteosarcoma metastasis. These findings may extend the function of UCA1 in osteosarcoma progression and provide a promising therapeutic target for osteosarcoma treatment.

Long non‑coding RNA UCA1 confers tamoxifen resistance in breast cancer endocrinotherapy through regulation of the EZH2/p21 axis and the PI3K/AKT signaling pathway

Tamoxifen is the gold standard for breast cancer endocrinotherapy. However, drug resistance remains a major limiting factor of tamoxifen treatment. Long non‑coding (lnc) RNA serves an important role in drug resistance; however, the molecular mechanisms of tamoxifen resistance in breast cancer endocrinotherapy are largely unclear. lncRNA urothelial cancer associated 1 (lncRNA UCA1, UCA1) has been proven to be dysregulated in human breast cancer and promotes cancer progression. In the present study, it was demonstrated that UCA1 was significantly upregulated in breast cancer tissues compared with healthy tissues. Furthermore, the expression level of UCA1 was significantly greater in tamoxifen‑resistant breast cancer cells (LCC2 and LCC9) when compared with those in the tamoxifen‑sensitive breast cancer cells (MCF‑7 and T47D). UCA1 silencing in LLC2 and LLC9 cells increased tamoxifen drug sensitivity by promoting cell apoptosis and arresting the cell cycle at the G2/M phase. Notably, the induced overexpression of UCA1 in MCF‑7 and T47D cells decreased the drug sensitivity of tamoxifen. The molecular mechanism involved in UCA1‑induced tamoxifen‑resistance was also investigated. It was identified that UCA1 was physically associated with the enhancer of zeste homolog 2 (EZH2), which suppressed the expression of p21 through histone methylation (H3K27me3) on the p21 promoter. In addition, it was demonstrated that UCA1 expression was paralleled to the phosphorylation of CAMP responsive element binding protein (CREB) and AKT. When LCC2 cells were treated with the phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT) signaling pathway inhibitor LY294002, the phosphorylation levels of CREB and AKT were significantly downregulated. Taken together, it was concluded that UCA1 regulates the EZH2/p21 axis and the PI3K/AKT signaling pathway in breast cancer, and may be a potential therapeutic target for solving tamoxifen resistance.

Emerging roles of lncRNAs in the post-transcriptional regulation in cancer

Accumulating evidence indicates that long non-coding RNAs (lncRNAs) can play a pivotal role in regulation of diverse cellular processes. In particular, lncRNAs can serve as master gene regulators at transcriptional and posttranscriptional levels, leading to tumorigenesis. In this review, we discuss latest developments in lncRNA-meditated gene expression at the post-transcriptional level, including gene splicing, mRNA stability, protein stability and nuclear trafficking.

Reciprocal regulations between miRNAs and HIF-1α in human cancers

Hypoxia inducible factor-1α (HIF-1α) is a central molecule involved in mediating cellular processes. Alterations of HIF-1α and hypoxically regulated microRNAs (miRNAs) are correlated with patients' outcome in various cancers, indicating their crucial roles on cancer development. Recently, an increasing number of studies have revealed the intricate regulations between miRNAs and HIF-1α in modulating a wide variety of processes, including proliferation, metastasis, apoptosis, and drug resistance, etc. miRNAs are a class of small noncoding RNAs which function as negative regulators by directly targeting mRNAs. Evidence shows that miRNAs can be regulated by HIF-1α at transcriptional level. In turn, HIF-1α itself can be modulated by many miRNAs whose alterations have been implicated in tumorigenesis, thus forming a reciprocal regulation network. These findings add a new layer of complexity to our understanding of HIF-1α regulatory networks. Here, we will provide a comprehensive overview of the current advances about the bidirectional interactions between HIF-1α and miRNAs in human cancers. Besides, the review will summarize the roles of miRNAs/HIF-1α crosstalk according to various cellular processes. Finally, the potential values of miRNAs/HIF-1α loops in clinical applications are discussed.

Knockdown of Long Noncoding RNA CAT104 Inhibits the Proliferation, Migration, and Invasion of Human Osteosarcoma Cells by Regulating MicroRNA-381

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. This study aimed to explore the effects of long noncoding RNA CAT104 and microRNA-381 (miR-381) on osteosarcoma cell proliferation, migration, invasion, and apoptosis, as well as the underlying potential mechanism. We found that CAT104 was highly expressed in osteosarcoma MG63 and OS-732 cells. Knockdown of CAT104 significantly inhibited OS-732 cell proliferation, migration, and invasion, but promoted cell apoptosis. CAT104 regulated the expression of miR-381, and miR-381 participated in the effects of CAT104 on OS-732 cells. Zinc finger E-box-binding homeobox 1 (ZEB1) was a direct target gene of miR-381, which was involved in the regulatory roles of miR-381 in OS-732 cell proliferation, migration, invasion, and apoptosis, as well as c-Jun N-terminal kinase (JNK) and Wnt/β-catenin pathways. In conclusion, our research verified that suppression of CAT104 exerted significant inhibitory effects on osteosarcoma cell proliferation, migration, and invasion by regulating the expression of miR-381 and downstream ZEB1, as well as JNK and Wnt/β-catenin pathways.

Knockdown of Urothelial Carcinoma-Associated 1 Suppressed Cell Growth and Migration Through Regulating miR-301a and CXCR4 in Osteosarcoma MHCC97 Cells

Liver cancer is one of the most common malignancies in the world and a leading cause of cancer-related mortality. Accumulating evidence has highlighted the critical role of long noncoding RNAs (lncRNAs) in various cancers. The present study aimed to explore the role of lncRNA urothelial carcinoma-associated 1 (UCA1) in cell growth and migration in MHCC97 cells and its underlying mechanism. First, we assessed the expression of UCA1 in MHCC97 and three other cell lines by RT-qPCR. Then the expression of UCA1, miR-301a, and CXCR4 in MHCC97 cells was altered by transient transfection. The effects of UCA1 and miR-301 on cell viability, migration, invasion, and apoptosis were assessed. The results revealed that UCA1 expression was relatively higher in MHCC97 cells than in MG63, hFOB1.19, and OS-732 cells. Knockdown of UCA1 reduced cell viability, inhibited migration and invasion, and promoted cell apoptosis. However, the effect of UCA1 knockdown on cell growth and migration was blocked by miR-301a overexpression, whose expression was regulated by UCA1. We also found that miR-301a positively regulated CXCR4 expression. CXCR4 inhibition reversed the effect of miR-301a overexpression on cell growth and migration. Moreover, miR-301a activated the Wnt/β-catenin and NF-κB pathways via regulating CXCR4. The present study demonstrated that UCA1 inhibition exerted an antigrowth and antimigration role in MHCC97 cells through regulating miR-301a and CXCR4 expression.

The novel long non‑coding RNA PRNCR1‑2 is involved in breast cancer cell proliferation, migration, invasion and cell cycle progression

Long non‑coding RNAs (lncRNAs) have recently been reported to act as important mediators of tumor initiation and progression. The present study aimed to investigate the expression and pathogenic roles of the lncRNA prostate cancer‑associated non‑coding RNA (PRNCR)1‑2 in breast cancer. The expression levels of PRNCR1‑2 were detected in breast cancer tissues and numerous breast cancer cell lines using reverse transcription‑quantitative polymerase chain reaction. Depletion of PRNCR1‑2 expression in breast cancer cells was conducted through small interfering RNA‑mediated silencing. Subsequently, cell proliferation was assessed by MTS assay, cell migration and invasion capacities were evaluated using the Transwell culture system, and cell cycle progression and apoptosis were analyzed by flow cytometry. Protein expression levels of the signaling components checkpoint kinase 2 (CHK2), protein kinase B (AKT), phosphorylated (p)‑CHK2 and p‑AKT were measured by western blotting. The results demonstrated that PRNCR1‑2 expression was significantly elevated in breast cancer tissues compared with in adjacent normal tissues. Furthermore, depletion of PRNCR1‑2 in HS‑578T and MDA‑MB‑231 breast cancer cells markedly suppressed their proliferation rates, migration and invasion capacities, and cell cycle progression; however, it had no effect on cell apoptosis. In addition, PRNCR1‑2 depletion increased CHK2 phosphorylation and decreased AKT phosphorylation in HS‑578T and MDA‑MB‑231 cells. In conclusion, the lncRNA PRNCR1‑2 may promote breast cancer cell proliferation, migration, invasion and cell cycle progression.

LncRNA UCA1 promotes cell proliferation, invasion and migration of laryngeal squamous cell carcinoma cells by activating Wnt/β-catenin signaling pathway

In view of the poor prognosis of laryngeal squamous cell carcinoma (LSCC) and the functionality of long non-coding (lnc)RNA UCA1 in different types of cancer, the present study aimed to investigate the role of UCA1 in the development and progression of LSCC. A total of 90 patients with LSCC and 90 healthy subjects were enrolled in the present study. Expression levels of UCA1 in tumor tissues and adjacent healthy tissues, as well as serum of patients with LSCC and normal controls were detected by reverse transcription-quantitative polymerase chain reaction. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic value of serum UCA1 for LSCC. Survival curves were plotted using the Kaplan-Meier method and employed to evaluate the prognosic values of serum UCA1 for LSCC. Cell proliferation, migration and invasion were detected using the cell proliferation assay, and Transwell migration and invasion assays, respectively. Expression levels of Wnt/β-catenin-associated proteins were detected by western blot analysis. Results indicated that the expression levels of UCA1 were significantly higher in tumor tissues compared with adjacent healthy tissues in the majority of patients with LSCC. In addition, serum levels of UCA1 were significantly higher in patients with LSCC coapred with healthy controls. UCA1 overexpression promoted, whereas UCA1 knockdown inhibited the proliferation, migration and invasion of LSCC cells. UCA1 overexpression activated the Wnt/β-catenin signaling pathway in LSCC cells, whereas treatment with Wnt inhibitor reduced the enhancing effects of UCA1 overexpression on the proliferation, migration and invasion of LSCC cells. The present findings suggest that UCA1 can promote cell proliferation, invasion and migration of LSCC cells by activating the Wnt/β-catenin signaling pathway.

Effects of shRNA-mediated silencing of PSMA7 on cell proliferation and vascular endothelial growth factor expression via the ubiquitin-proteasome pathway in cervical cancer

This study aims to evaluate the effects of PSMA7 silencing on cervical cancer (CC) cell proliferation and vascular endothelial growth factor (VEGF) expression through the ubiquitin-proteasome pathway. CC tissues (n = 43) and normal tissues (n = 27) were first collected from patients. Human CC cell line (SiHa) and human normal cervical epithelial cells (H8) were obtained and classified into the normal, blank, negative control (NC), PSMA7-shRNA1, and PSMA7-shRNA2 groups, respectively. In situ hybridization was used to detect the expressions of wild-type and mutant p53 proteins. Immunofluorescence assay was carried out to test the activity of 20S proteasomes. Reverse transcription quantitative polymerase chain reaction and Western blot analysis were both performed to determine the expressions of PSMA7, ubiquitin, P27, P53, and VEGF in sample tissues and cells. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to analyze cell proliferation rates, and flow cytometry was used to analyze the cell cycle and the apoptotic rate. Compared with normal tissues, CC tissues showed increased expression levels of PSMA7, ubiquitin, p53, VEGF as well as increased activity of 20S proteasomes but exhibited a decrease in p27 expression. Compared with the blank and NC groups, the PSMA7-shRNA1 and PSMA7-shRNA2 groups all had decreased expression levels of PSMA7, ubiquitin, p53, and VEGF as well as decreased cell proliferation, 20S proteasomes activity, and cell number in the S phase, increased p27 expression, cell apoptosis and cell number in the G0/G1 phase. Our study demonstrated that PSMA7 silencing can suppress CC cell proliferation and VEGF expression in addition to promoting cell apoptosis through inhibiting the UPP signaling pathway.

The emerging role of lncRNAs in inflammatory bowel disease

Dysregulation of long noncoding RNA (lncRNA) expression is linked to the development of various diseases. Recently, an emerging body of evidence has indicated that lncRNAs play important roles in the pathogenesis of inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative Colitis (UC). In IBD, lncRNAs have been shown to be involved in diverse processes, including the regulation of intestinal epithelial cell apoptosis, association with lipid metabolism, and cell–cell interactions, thereby enhancing inflammation and the functional regulation of regulatory T cells. In this review, we aim to summarize the current knowledge regarding the role of lncRNAs in IBD and highlight potential avenues for future investigation. We also collate potentially immune-relevant, IBD-associated lncRNAs identified through a built-by association analysis with respect to their neighboring protein-coding genes within IBD-susceptible loci. We further underscore their importance by highlighting their enrichment for various aspects of immune system regulation, including antigen processing/presentation, immune cell proliferation and differentiation, and chronic inflammatory responses. Finally, we summarize the potential of lncRNAs as diagnostic biomarkers in IBD.

Studying long noncoding RNAs (lncRNAs) may improve diagnosis and treatment of inflammatory bowel disease (IBD). These RNAs are found between genes in DNA regions previously thought to be “junk,” and have recently been shown to be important in development of various diseases. IBD, which includes both Crohn’s disease and ulcerative colitis, damages the digestive tract lining, causing pain and chronic diarrhea. A better understanding of IBD’s complex causes is needed to identify more effective treatments. Flemming Pociot at the Steno Diabetes Center in Gentofte, Denmark, and co-workers reviewed recent research linking lncRNAs and IBD. They discuss how lncRNAs’ roles in immunity and inflammation influence IBD development, describing how particular lncRNAs are related to IBD. Promising avenues for further research are highlighted, including the use of lncRNAs as biomarkers of IBD, which can be difficult to diagnose.

LONG-NONCODING RNAs in gastroesophageal cancers

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

Platforms for Investigating LncRNA Functions

Prior to the sequencing of the human genome, it was presumed that most of the DNA coded for proteins. However, with the advent of next-generation sequencing, it has now been recognized that most complex eukaryotic genomes are in fact transcribed into noncoding RNAs (ncRNAs), including a family of transcripts referred to as long noncoding RNAs (lncRNAs). LncRNAs have been implicated in many biological processes ranging from housekeeping functions such as transcription to more specialized functions such as dosage compensation or genomic imprinting, among others. Interestingly, lncRNAs are not limited to a defined set of functions but can regulate varied activities such as messenger RNA degradation, translation, and protein kinetics or function as RNA decoys or scaffolds. Although still in its infancy, research into the biology of lncRNAs has demonstrated the importance of lncRNAs in development and disease. However, the specific mechanisms through which these lncRNAs act remain poorly defined. Focused research into a small number of these lncRNAs has provided important clues into the heterogeneous nature of this family of ncRNAs. Due to the complex diversity of lncRNA function, in this review, we provide an update on the platforms available for investigators to aid in the identification of lncRNA function.

Dual functions for OVAAL in initiation of RAF/MEK/ERK prosurvival signals and evasion of p27-mediated cellular senescence

Here, we report that the long noncoding RNA (lncRNA) ovarian adenocarcinoma-amplified lncRNA (OVAAL) is a mediator of cancer cell resistance, counteracting the effects of apoptosis-inducing agents acting through both the extrinsic and intrinsic pathways. Building upon previous reports associating OVAAL amplification with ovarian and endometrial cancers, we now show that OVAAL overexpression occurs during the pathogenesis of colorectal cancer and melanoma. Mechanistically, our findings also establish that OVAAL expression more generally contributes a prosurvival role to cancer cells under steady-state conditions. OVAAL accomplishes these actions utilizing distinct functional modalities: one promoting activation of RAF/MEK/ERK signaling and the other blocking cell entry into senescence. Our study demonstrates that expression of a single OVAAL in cancer cells drives two distinct but coordinated actions contributing to cancer pathology.

Long noncoding RNAs (lncRNAs) function through a diverse array of mechanisms that are not presently fully understood. Here, we sought to find lncRNAs differentially regulated in cancer cells resistant to either TNF-related apoptosis-inducing ligand (TRAIL) or the Mcl-1 inhibitor UMI-77, agents that act through the extrinsic and intrinsic apoptotic pathways, respectively. This work identified a commonly up-regulated lncRNA, ovarian adenocarcinoma-amplified lncRNA (OVAAL), that conferred apoptotic resistance in multiple cancer types. Analysis of clinical samples revealed OVAAL expression was significantly increased in colorectal cancers and melanoma in comparison to the corresponding normal tissues. Functional investigations showed that OVAAL depletion significantly inhibited cancer cell proliferation and retarded tumor xenograft growth. Mechanically, OVAAL physically interacted with serine/threonine-protein kinase 3 (STK3), which, in turn, enhanced the binding between STK3 and Raf-1. The ternary complex OVAAL/STK3/Raf-1 enhanced the activation of the RAF protooncogene serine/threonine-protein kinase (RAF)/mitogen-activated protein kinase kinase 1 (MEK)/ERK signaling cascade, thus promoting c-Myc–mediated cell proliferation and Mcl-1–mediated cell survival. On the other hand, depletion of OVAAL triggered cellular senescence through polypyrimidine tract-binding protein 1 (PTBP1)–mediated p27 expression, which was regulated by competitive binding between OVAAL and p27 mRNA to PTBP1. Additionally, c-Myc was demonstrated to drive OVAAL transcription, indicating a positive feedback loop between c-Myc and OVAAL in controlling tumor growth. Taken together, these results reveal that OVAAL contributes to the survival of cancer cells through dual mechanisms controlling RAF/MEK/ERK signaling and p27-mediated cell senescence.

LncRNA UCA1 promotes tumor metastasis by inducing miR-203/ZEB2 axis in gastric cancer

Increasing studies showed that long-noncoding RNAs (lncRNAs) play important roles in the biological processes, including cancer initiation and progression. However, little is known about the exact role and regulation mechanism of lncRNA UCA1 during the progression of gastric cancer (GC). In this study, we found that UCA1 was aberrantly elevated in gastric cancer tissues, and was significantly associated with lymph node metastasis and TNM stage. In vivo and in vitro, enforced UCA1 level promoted cell migration and invasion of GC cell. Depleted UCA1 expression level attenuated the ability of cell migration and invasion in GC. And then, we detected that expression level of ZEB2, a transcription factor related to tumor metastasis, was regulated by UCA1 in GC cells. miR-203 targets and suppresses to ZEB2 expression. Furthermore, we found that UCA1 could directly interact with miR-203 and lead to the release of miR-203-targeted transcripts ZEB2. Herein, we revealed the novel mechanism of UCA1 on regulating metastasis-related gene by sponge regulatory axis during GC metastasis. Our findings indicated that UCA1 plays a critical role in metastatic GC by mediating sponge regulatory axis miR-203/ZEB2. To explore function of UCA1-miR-203-ZEB2 axis may provide an informative biomarker of malignancy and a highly selective anti-GC therapeutic target.

Epigenetic Regulation by lncRNAs: An Overview Focused on UCA1 in Colorectal Cancer

Colorectal cancers have become the second leading cause of cancer-related deaths. In particular, acquired chemoresistance and metastatic lesions occurring in colorectal cancer are a major challenge for chemotherapy treatment. Accumulating evidence shows that long non-coding (lncRNAs) are involved in the initiation, progression, and metastasis of cancer. We here discuss the epigenetic mechanisms through which lncRNAs regulate gene expression in cancer cells. In the second part of this review, we focus on the role of lncRNA Urothelial Cancer Associated 1 (UCA1) to integrate research in different types of cancer in order to decipher its putative function and mechanism of regulation in colorectal cancer cells. UCA1 is highly expressed in cancer cells and mediates transcriptional regulation on an epigenetic level through the interaction with chromatin modifiers, by direct regulation via chromatin looping and/or by sponging the action of a diversity of miRNAs. Furthermore, we discuss the role of UCA1 in the regulation of cell cycle progression and its relation to chemoresistance in colorectal cancer cells.

Cationic vesicles for efficient shRNA transfection in the MCF-7 breast cancer cell line

INTRODUCTION

Novel and safe delivery solutions for RNAi therapeutics are essential to obtain the full potential of cancer gene therapy.

METHODS

In this study, cationic vesicular nanocarrier was applied for delivering lnc urothelial carcinoma-associated 1 (lnc UCA1) shRNA expression vector to MCF-7 cells. The physicochemical characteristics, cytotoxicity, and transfection efficiency of cationic vesicles prepared from various molar ratios of amphiphilic surfactant Tween 80 (T), squalene (S), cationic charge lipid didodecyldimethylammonium bromide, and polyethylenimine were investigated. The particle sizes of the vesicles in the nanosize range were determined by dynamic light scattering and transmission electron microscopy.

RESULTS

Gel protection assay with agarose gel electrophoresis showed cationic vesicles can protect the shRNA plasmid from DNase 1 enzyme. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium, inner salt result showed no significant cytotoxicity was caused in MCF-7 cancer cell line by (T:S):polyethylenimine cationic vesicles. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium, inner salt assay, fluorescence microscope images, and flow cytometry analyses confirmed that (T:S)1,040 μM with 4.3 μg/mL of PEI vesicles provided effective transfection without significant cytotoxicity. Furthermore, we found efficient UCA1 shRNA transfection and significant (P<0.05) cell cycle arrest and apoptosis in MCF-7 cancer cells.

CONCLUSION

The novel nonviral vesicular nanocarrier, (T:S)1,040 μM with 4.3 μg/mL of PEI, might be safe and efficient for cancer gene therapy and can be used in further in vitro and in vivo studies.

Microarray analysis of lncRNA expression in rabies virus infected human neuroblastoma cells

Rabies, caused by the rabies virus (RABV), is the oldest known zoonotic infectious disease. Although the molecular mechanisms of RABV pathogenesis have been investigated extensively, the interactions between host and RABV are not clearly understood. It is now known that long non-coding RNAs (lncRNAs) participate in various physiological and pathological processes, but their possible roles in the host response to RABV infection remain to be elucidated. To better understand the pathogenesis of RABV, RNAs from RABV-infected and uninfected human neuroblastoma cells (SK-N-SH) were analyzed using human lncRNA microarrays. We identified 896 lncRNAs and 579 mRNAs that were differentially expressed after infection, indicating a potential role for lncRNAs in the immune response to RABV. Differentially expressed RNAs were examined using Gene Ontology (GO) analysis and were tentatively assigned to biological pathways using the Kyoto Encyclopedia of Genes and Genomes (KEGG). A lncRNA-mRNA-transcription factor co-expression network was constructed to relate lncRNAs to regulatory factors and pathways that may be important in virus-host interactions. The network analysis suggests that E2F4, TAF7 and several lncRNAs function as transcriptional regulators in various signaling pathways. This study is the first global analysis of lncRNA and mRNA co-expression during RABV infection, provides deeper insight into the mechanism of RABV pathogenesis, and reveals promising candidate for future investigation.

The regulatory roles of lncRNAs in the process of breast cancer invasion and metastasis

Breast cancer (BC) is the most common cancer and principal cause of death among females worldwide. Invasion and metastasis are major causes which influence the survival and prognosis of BC. Therefore, to understand the molecule mechanism underlying invasion and metastasis is paramount for developing strategies to improve survival and prognosis in BC patients. Recent studies have reported that long non-coding RNAs (lncRNAs) play critical roles in the regulation of BC invasion and metastasis through a variety of molecule mechanisms that endow cells with an aggressive phenotype. In this article, we focused on the function of lncRNAs on BC invasion and metastasis through participating in epithelial-to-mesenchymal transition, strengthening cancer stem cells generation, serving as competing endogenous lncRNAs, influencing multiple signaling pathways as well as regulating expressions of invasion-metastasis related factors, including cells adhesion molecules, extracellular matrix, and matrix metallo-proteinases. The published work described has provided a better understanding of the mechanisms underpinning the contribution of lncRNAs to BC invasion and metastasis, which may lay the foundation for the development of new strategies to prevent BC invasion and metastasis.

Long noncoding RNA UCA1 promotes the proliferation of hypoxic human pulmonary artery smooth muscle cells

Our study explored the effects of lncRNA UCA1 on the proliferation and apoptosis in hypoxic human pulmonary artery smooth muscle cells (HPASMCs) and highlighted the endogenous relationship between UCA1, ING5, and hnRNP I in cell proliferation. Hypoxia-induced HPASMCs were used to simulate pulmonary arterial hypertension in vitro. Microarray assay was adopted to screen the dysregulated expressed lncRNAs in HPASMCs to find out the target gene of our study. And RT-qPCR was performed to detect the expression of lncRNA UCA1 under hypoxia and normoxia. After transfection, the relationship between UCA1 and cell proliferation in HPASMCs under hypoxia were determined by cell proliferation assay and relative expression of PCNA. Next, ELISA assays were conducted to measure the protein levels of PCNA and ING5. What's more, flow cytometry was employed to measure the apoptosis rate in differentially UCA1-expressed HPASMCs. RIP assays were conducted to further clarify the endogenous relationship between UCA1 and ING5 in hypoxic HPASMCs. Finally, the effects of ING5 to HPASMCs were detected after transfection of ING5 and UCA1 to figure out the role of ING5 in HPASMCs. Hypoxia was revealed to induce proliferation and inhibited apoptosis in HPASMCs. Besides, UCA1 was confirmed to be highly expressed under hypoxia compared with normoxia. UCA1 boosted cell proliferation under hypoxia in HPASMCs. However, the apoptosis was suppressed in the hypoxic HPASMCs transfected with pcDNA3.1-UCA1. Further, mechanism studies found that UCA1 competed with ING5 for hnRNP I, so that upregulating UCA1 inhibited the protein levels of ING5. And finally we found that ING5 restrained cell viability, but promoted cell apoptosis in hypoxic HPASMCs, which was reversed by UCA1 over-expression. In summary, our findings manifested that UCA1 promoted proliferation and restrained apoptosis by competing with ING5 for hnRNP I in HPASMCs induced by hypoxia, indicating their potential roles for the cure of hypoxic pulmonary hypertension.

Long non-coding RNA-dependent mechanism to regulate heme biosynthesis and erythrocyte development

In addition to serving as a prosthetic group for enzymes and a hemoglobin structural component, heme is a crucial homeostatic regulator of erythroid cell development and function. While lncRNAs modulate diverse physiological and pathological cellular processes, their involvement in heme-dependent mechanisms is largely unexplored. In this study, we elucidated a lncRNA (UCA1)-mediated mechanism that regulates heme metabolism in human erythroid cells. We discovered that UCA1 expression is dynamically regulated during human erythroid maturation, with a maximal expression in proerythroblasts. UCA1 depletion predominantly impairs heme biosynthesis and arrests erythroid differentiation at the proerythroblast stage. Mechanistic analysis revealed that UCA1 physically interacts with the RNA-binding protein PTBP1, and UCA1 functions as an RNA scaffold to recruit PTBP1 to ALAS2 mRNA, which stabilizes ALAS2 mRNA. These results define a lncRNA-mediated posttranscriptional mechanism that provides a new dimension into how the fundamental heme biosynthetic process is regulated as a determinant of erythrocyte development.

LncRNAs modulate diverse physiological cellular processes, however, their involvement in heme-dependent processes are not yet clear. Here the authors reveal the role of lncRNA UCA1 in erythroid cell development.

Long non-coding RNA LINC-01572:28 inhibits granulosa cell growth via a decrease in p27 (Kip1) degradation in patients with polycystic ovary syndrome

BACKGROUND

Disordered folliculogenesis is a key feature of polycystic ovary syndrome (PCOS), but the underlying molecular mechanism remains unclear.

METHODS

Long non-coding RNA (lncRNA) expression in luteinized granulosa cells (hLGCs) derived from women with and without PCOS were analyzed using microarray and qRT-PCR. Immortalized human granulosa cell lines were cultured for proliferation assays after transfection with the LINC-01572:28 over-expression vector in the presence or absence of p27 siRNA. Protein expression analysis, rescue assays, and RNA immunoprecipitation (RIP) were used to confirm the LINC-01572:28 substrate.

FINDINGS

LINC-01572:28 and p27 protein were elevated whereas proliferating cell nuclear antigen protein was decreased in the hLGCs of women with PCOS. LINC-01572:28 expression was positively correlated with basal testosterone levels. Over-expression of LINC-01572:28 inhibited cell proliferation and impeded G1/S transition, which were partially reversed by siRNA-mediated p27 knockdown.

INTERPRETATION

Our findings, therefore, suggest that LINC-01572:28 suppresses cell proliferation and cell cycle progression by reducing the degradation of p27 protein via SKP2 binding.

Interaction of long-chain non-coding RNAs and important signaling pathways on human cancers (Review)

Long non-coding RNAs (lncRNAs) usually refer to non-coding RNA transcripts >200 nucleotides in length. In terms of the full genomic transcript, the proportion of lncRNAs far exceeds that of coding RNA. Initially, lncRNAs were considered to be the transcriptional noise of genes, but it has since been demonstrated that lncRNAs serve an important role in the regulation of cellular activities through interaction with DNA, RNA and protein. Numerous studies have demonstrated that various intricate signaling pathways are closely related to lncRNAs. Here, we focus on a large number of studies regarding the interaction of lncRNAs with important signaling pathways. It is comprehensively illustrated that lncRNAs regulate key metabolic components and regulatory factors of signaling pathways to affect the biological activities of tumor cells. Evidence suggests that the abnormal expression or mutation of lncRNAs in human tumor cells, and their interaction with signaling pathways, may provide a basis and potential target for the diagnosis and treatment of human cancers.

Long non-coding RNA CUDR promotes malignant phenotypes in pancreatic ductal adenocarcinoma via activating AKT and ERK signaling pathways

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a marked potential for invasion and metastasis. Emerging evidence has suggested that dysregulation of long non-coding RNAs (lncRNAs) is associated with the development of multiple types of cancer. However, the function of lncRNAs in PDAC is poorly known. In the present study, a microarray assay was used to screen for differently expressed lncRNAs in PDAC and it was identified that cancer upregulated drug resistance (CUDR) was upregulated in PDAC. CUDR increased PDAC cell proliferation, migration and invasion, inhibited apoptosis, and promoted drug resistance; it also regulated the PDAC cell epithelial-mesenchymal transition. The CUDR-induced PDAC malignant phenotypes is via the protein kinase B and extracellular-signal-regulated kinase signaling pathways. Downregulation of CUDR may be a novel therapeutic strategy to prevent PDAC development and drug resistance in the future.

Upregulation of long noncoding RNA MEG3 inhibits the osteogenic differentiation of periodontal ligament cells

OBJECTIVE

This study aims to discuss long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) function of regulating osteogenesis in human periodontal ligament cells (hPDLCs).

METHODS

First, use of a mineralizing solution induced osteogenic differentiation of hPDLCs to establish a differentiated cell model. Through microarray analysis, we selected a lncRNA MEG3 with marked changes between differentiated and undifferentiated cells. The quantitative polymerase chain reaction was used to detect the MEG3 content and an enzyme-linked immunosorbent assay was used to detect changes in related proteins. Cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and apoptosis was measured by flow cytometry. Alizarin red staining was also used to evaluate cells' osteogenic level. Finally, RNA-binding protein immunoprecipitation assays were conducted to further clarify the endogenous relationship between MEG3 and bone morphogenetic protein 2 ( BMP2) in hPDLCs.

RESULTS

MEG3 was downregulated in osteogenic differentiation hPDLCs induced by mineralizing solution. Overexpression of MEG3 inhibited cell viability and increased cell apoptosis. MEG3 overexpression can reverse osteogenic differentiation induced by mineralizing solution. MEG3 can suppress BMP2 through interaction with heterogeneous nuclear ribonucleoprotein I.

CONCLUSION

Upregulation of MEG3 inhibits the osteogenic differentiation of periodontal ligament cells by downregulating BMP2 expression.

Z Probe, An Efficient Tool for Characterizing Long Non-Coding RNA in FFPE Tissues

Formalin-fixed paraffin embedded (FFPE) tissues are a valuable resource for biomarker discovery in order to understand the etiology of different cancers and many other diseases. Proteins are the biomarkers of interest with respect to FFPE tissues as RNA degradation is the major challenge in these tissue samples. Recently, non-protein coding transcripts, long non-coding RNAs (lncRNAs), have gained significant attention due to their important biological actions and potential involvement in cancer. RNA sequencing (RNA-seq) or quantitative reverse transcription-polymerase chain reaction (qRT-PCR) are the only validated methods to evaluate and study lncRNA expression and neither of them provides visual representation as immunohistochemistry (IHC) provides for proteins. We have standardized and are reporting a sensitive Z probe based in situ hybridization method to visually identify and quantify lncRNA in FFPE tissues. This assay is highly sensitive and identifies transcripts visible within different cell types and tumors. We have detected a scarcely expressed tumor suppressor lncRNA NRON (non-coding repressor of nuclear factor of activated T-cells (NFAT)), a moderately expressed oncogenic lncRNA UCA1 (urothelial cancer associated 1), and a highly studied and expressed lncRNA MALAT1 (metastasis associated lung adenocarcinoma transcript 1) in different cancers. High MALAT1 staining was found in colorectal, breast and pancreatic cancer. Additionally, we have observed an increase in MALAT1 expression in different stages of colorectal cancer.

TRMP, a p53-inducible long noncoding RNA, regulates G1/S cell cycle progression by modulating IRES-dependent p27 translation

The tumor suppressor p53 plays a pivotal role in the protection against cancer. Increasing evidence suggests that long noncoding RNA (lncRNA) plays an important role in the regulation of the p53 pathway, however, the detailed mechanisms remain to be further elucidated. In this study, we report a new p53-inducible lncRNA that we termed TRMP (TP53-regulated modulator of p27). As a direct transcriptional target of p53, TRMP plays an unexpected pro-survival function. Knockdown of TRMP inhibits cell proliferation by inducing a G1 cell cycle arrest. Mechanistically, TRMP suppresses internal ribosomal entry site (IRES)-dependent translation of p27 by competing p27 mRNA for polypyrimidine tract-binding protein 1 (PTBP1) binding. Furthermore, TRMP is able to regulate cell proliferation, G1/S cell cycle progression, and tumor xenograft growth via the inhibition of p27. Taken together, these findings suggest lncRNA as a new layer to fine-tune the p53 response and reveal TRMP as an important downstream effector of p53 activity.