Long Non-Coding RNA CCAT1 Acts as a Competing Endogenous RNA to Regulate Cell Growth and Differentiation in Acute Myeloid Leukemia

Comprehensive analysis of differentially expressed profiles of lncRNAs and construction of miR-133b mediated ceRNA network in colorectal cancer

Background

Growing evidence suggests that long non-coding RNAs (lncRNAs) play a key role in tumorigenesis. However, the mechanism remains largely unknown.

Results

Thousands of significantly dysregulated lncRNAs and mRNAs were identified by microarray. Furthermore, a miR-133b-meditated lncRNA-mRNA ceRNA network was revealed, a subset of which was validated in 14 paired CRC patient tumor/non-tumor samples. Gene set enrichment analysis (GSEA) results demonstrated that lncRNAs ENST00000520055 and ENST00000535511 shared KEGG pathways with miR-133b target genes.

Materials and Methods

We used microarrays to survey the lncRNA and mRNA expression profiles of colorectal cancer and para-cancer tissues. Gene Ontology (GO) and KEGG pathway enrichment analyses were performed to explore the functions of the significantly dysregulated genes. An innovate method was employed that combined analyses of two microarray data sets to construct a miR-133b-mediated lncRNA-mRNA competing endogenous RNAs (ceRNA) network. Quantitative RT-PCR analysis was used to validate part of this network. GSEA was used to predict the potential functions of these lncRNAs.

Conclusions

This study identifies and validates a new method to investigate the miR-133b-mediated lncRNA-mRNA ceRNA network and lays the foundation for future investigation into the role of lncRNAs in colorectal cancer.

A 4-lncRNA scoring system for prognostication of adult myelodysplastic syndromes

Long noncoding RNAs (lncRNAs) not only participate in normal hematopoiesis but also contribute to the pathogenesis of acute leukemia. However, their clinical and prognostic relevance in myelodysplastic syndromes (MDSs) remains unclear to date. In this study, we profiled lncRNA expressions in 176 adult patients with primary MDS, and identified 4 lncRNAs whose expression levels were significantly associated with overall survival (OS). We then constructed a risk-scoring system with the weighted sum of these 4 lncRNAs. Higher lncRNA scores were associated with higher marrow blast percentages, higher-risk subtypes of MDSs (based on both the Revised International Prognostic Scoring System [IPSS-R] and World Health Organization classification), complex cytogenetic changes, and mutations in RUNX1, ASXL1, TP53, SRSF2, and ZRSR2, whereas they were inversely correlated with SF3B1 mutation. Patients with higher lncRNA scores had a significantly shorter OS and a higher 5-year leukemic transformation rate compared with those with lower scores. The prognostic significance of our 4-lncRNA risk score could be validated in an independent MDS cohort. In multivariate analysis, higher lncRNA scores remained an independent unfavorable risk factor for OS (relative risk, 4.783; P < .001) irrespective of age, cytogenetics, IPSS-R, and gene mutations. To our knowledge, this is the first report to provide a lncRNA platform for risk stratification of MDS patients. In conclusion, our integrated 4-lncRNA risk-scoring system is correlated with distinctive clinical and biological features in MDS patients, and serves as an independent prognostic factor for survival and leukemic transformation. This concise yet powerful lncRNA-based scoring system holds the potential to improve the current risk stratification of MDS patients.

Colon cancer associated transcripts in human cancers

Long non-coding RNAs serve as important regulators in complicated cellular activities, including cell differentiation, proliferation and death. Dysregulation of long non-coding RNAs occurs in the formation and progression of cancers. The family of colon cancer associated transcripts, long non-coding RNAs colon cancer associated transcript-1 and colon cancer associated transcript-2 are known as oncogenes involved in various cancers. Colon cancer associated transcript-1 is a novel lncRNA located in 8q24.2, and colon cancer associated transcript-2 maps to the 8q24.21 region encompassing rs6983267. Colon cancer associated transcripts have close associations with clinical characteristics, such as lymph node metastasis, high TNM stage and short overall survival. Knockdown of them can reverse the malignant phenotypes of cancer cells, including proliferation, migration, invasion and apoptosis. Moreover, they can increase the expression level of c-MYC and oncogenic microRNAs via activating a series of complex mechanisms. In brief, the family of colon cancer associated transcripts may serve as potential biomarkers or therapeutic targets for human cancers.

MicroRNAs and acute myeloid leukemia: therapeutic implications and emerging concepts

Acute myeloid leukemia (AML) is a deadly hematologic malignancy characterized by the uncontrolled growth of immature myeloid cells. Over the past several decades, we have learned a tremendous amount regarding the genetic aberrations that govern disease development in AML. Among these are genes that encode noncoding RNAs, including the microRNA (miRNA) family. miRNAs are evolutionarily conserved small noncoding RNAs that display important physiological effects through their posttranscriptional regulation of messenger RNA targets. Over the past decade, studies have identified miRNAs as playing a role in nearly all aspects of AML disease development, including cellular proliferation, survival, and differentiation. These observations have led to the study of miRNAs as biomarkers of disease, and efforts to therapeutically manipulate miRNAs to improve disease outcome in AML are ongoing. Although much has been learned regarding the importance of miRNAs in AML disease initiation and progression, there are many unanswered questions and emerging facets of miRNA biology that add complexity to their roles in AML. Moving forward, answers to these questions will provide a greater level of understanding of miRNA biology and critical insights into the many translational applications for these small regulatory RNAs in AML.

Long non-coding RNA CCAT1/miR-218/ZFX axis modulates the progression of laryngeal squamous cell cancer

Long non-coding RNAs have been proved to be closely associated with different cancers. This study was designed to elucidate the function and mechanisms of colon cancer-associated transcript-1 in the progression of human laryngeal squamous cell cancer. Expressions of colon cancer-associated transcript-1, microRNA-218, and zinc finger protein, X-linked messenger RNA were measured using quantitative real-time polymerase chain reaction, and the expression level of zinc finger protein, X-linked protein was detected using western blot. Proliferation and invasion of laryngeal squamous cell cancer cell lines were detected by Cell Counting Kit-8 assay and Transwell invasion assay, respectively. Luciferase assay was used to confirm whether microRNA-218 is a target of colon cancer-associated transcript-1 and whether microRNA-218 directly binds to 3'-untranslated region of zinc finger protein, X-linked messenger RNA. Effect of colon cancer-associated transcript-1 on tumor growth was observed through xenograft mice models in vivo. The results showed that expressions of colon cancer-associated transcript-1 and zinc finger protein, X-linked were significantly higher while microRNA-218 expression was significantly lower in the laryngeal squamous cell cancer tissues than those in the adjacent normal tissues. MicroRNA-218 overexpression or zinc finger protein, X-linked silencing significantly suppressed proliferation and invasion of laryngeal squamous cell cancer cells. Moreover, knockdown of colon cancer-associated transcript-1 significantly inhibited proliferation and invasion of laryngeal squamous cell cancer cells, which were reversed by microRNA-218 downregulation or zinc finger protein, X-linked upregulation. Finally, colon cancer-associated transcript-1 silencing inhibited xenograft tumor growth of laryngeal squamous cell cancer in vivo. In conclusion, colon cancer-associated transcript-1 knockdown inhibits proliferation and invasion of laryngeal squamous cell cancer cells through enhancing zinc finger protein, X-linked by sponging microRNA-218, elucidating a novel colon cancer-associated transcript-1-microRNA-218-zinc finger protein, X-linked regulatory axis in laryngeal squamous cell cancer and providing a promising therapeutic target for laryngeal squamous cell cancer patients.

Inhibition of proliferation and invasion of hepatocellular carcinoma cells by lncRNA-ASLNC02525 silencing and the mechanism

One of the most differentially expressed long non-coding RNAs (lncRNAs) that we identified by high throughput screening from liver cancer and para-carcinoma tissues, ASLNC02525, was highly expressed in the tissues and cell lines of liver cancer but not in adjacent tissues or normal hepatic cells. Knockdown of ASLNC02525 in hepatocellular carcinoma cells inhibited the proliferation and invasion. In the process, expression level of transcription factor twist1 (twist‑related protein 1) was reduced, but no change at transcription level was observed. According to bioinformatics analysis, ASLNC02525 may play a crucial role in inactivation of regulation of twist1 by hsa-miRNA-489-3p. The mechanism study revealed that ASLNC02525, as an RNA sponge, broke the negative regulation of twist1 by hsa-miRNA-489-3p, and once ASLNC02525 was silenced, the highly expressed hsa-miRNA‑489-3p regained its regulation on twist1 and inhibited the proliferation and invasion. The importance of this study lies in shedding light on the potential for lncRNAs to become targets for gene therapy, by demonstrating that lncRNAs can suppress tumor inhibiting activity of miRNAs via breaking regulation of some miRNA target genes.

miRNA and lncRNA as biomarkers in cholangiocarcinoma(CCA)

The microRNAs are a group of 20 nucleotides-long non-coding RNAs. By binding to the 3'UTR region of target mRNA, microRNAs can perform extensive actions mediating gene expression at post-trancriptional stages. It makes microRNAs serve as very crucial regulators in various biological progress including carcinogenesis. Long non-coding RNAs, however, are a subgroup of RNA with the length of 200 nucleotides. Unlike microRNAs, long non-coding RNAs can form secondary of tertiary domain based on their length. With the ability of directly interacting with DNA, RNA, protein, long non-coding RNAs have promoting or inhibitive functions in gene expression regulation. Furthermore, the abnormal expression of certain long non-coding RNAs has roused people's interest in the role of long non-coding RNAs in tumorigenesis. Although the connection between microRNA/long non-coding RNA and CCA has been a hot field to researchers, the link between molecular mechanism and clinical outcome has been barely built. This review takes a retrospect at the latest researches on the link between microRNA/long non-coding RNA and cholangiocarcinoma and the potential of microRNA/long non-coding RNA serving as distinctive biomarkers for CCA in clinical practice.

Long non-coding RNA CCAT1/miR-148a axis promotes osteosarcoma proliferation and migration through regulating PIK3IP1

Osteosarcoma is the most frequent type of malignant primary bone tumor. Although many efforts have been made, the survival rate of osteosarcoma still remains unsatisfied. Long non-coding RNAs (lncRNAs) have been demonstrated to be associated with many diseases including tumors, and involved in the regulation of a wide array of pathophysiological processes. Colon-cancer-associated transcript-1 (CCAT1) was first identified in colon cancer and has subsequently been reported to perform many functions in tumor progression. The present study aimed to comprehensively explore the biological functions of CCAT1 and its underlying mechanism in osteosarcoma cells. Our findings revealed that CCAT1 was upregulated in osteosarcoma tissues and cells, and was involved in the proliferation and migration of osteosarcoma via regulating miR-148a/phosphatidyl inositol 3-kinase interacting protein 1 (PIK3IP1) signal pathway.

Long Non-Coding RNAs: Key Regulators of Epithelial-Mesenchymal Transition, Tumour Drug Resistance and Cancer Stem Cells

Epithelial mesenchymal transition (EMT), the adoption by epithelial cells of a mesenchymal-like phenotype, is a process co-opted by carcinoma cells in order to initiate invasion and metastasis. In addition, it is becoming clear that is instrumental to both the development of drug resistance by tumour cells and in the generation and maintenance of cancer stem cells. EMT is thus a pivotal process during tumour progression and poses a major barrier to the successful treatment of cancer. Non-coding RNAs (ncRNA) often utilize epigenetic programs to regulate both gene expression and chromatin structure. One type of ncRNA, called long non-coding RNAs (lncRNAs), has become increasingly recognized as being both highly dysregulated in cancer and to play a variety of different roles in tumourigenesis. Indeed, over the last few years, lncRNAs have rapidly emerged as key regulators of EMT in cancer. In this review, we discuss the lncRNAs that have been associated with the EMT process in cancer and the variety of molecular mechanisms and signalling pathways through which they regulate EMT, and finally discuss how these EMT-regulating lncRNAs impact on both anti-cancer drug resistance and the cancer stem cell phenotype.

The lncRNA CCAT1 Upregulates Proliferation and Invasion in Melanoma Cells via Suppressing miR-33a

It is increasingly evident that various long noncoding RNAs (lncRNAs) participate in the tumorigenesis of multiple tumors, including melanoma. lncRNAs have been validated as oncogenic factors in various tumors; however, the potential regulatory mechanism of CCAT1 in melanoma is still unclear. The purpose of this study was to investigate the regulation of CCAT1 on melanoma genesis. The expression of CCAT1 in melanoma tissue and cell lines was measured using qRT-PCR. Interference oligonucleotide or mimic sequences were applied to up- or downregulate RNA expression. CCK-8 and colony formation assays were performed to detect the proliferation capability. Transwell assay was used to assess the migration and invasion capacities. Bioinformatics analysis was performed to predict the target miRNAs of CCAT1. Expression of CCAT1 was significantly upregulated in melanoma tissue and cell lines. CCAT1 knockdown observably suppressed the proliferation, migration, and invasion abilities. Bioinformatics analysis predicted that miR-33a acted as a target of CCAT1, which was confirmed by dual-luciferase reporter assay. CCAT1 knockdown reversed the tumor-promoting ability of the miR-33a inhibitor. CCAT1 acts as an oncogenic factor in the genesis of melanoma and exerts tumor-promoting roles via sponging miR-33a, providing a novel insight for competing endogenous RNA (ceRNA) in the tumorigenesis of melanoma.

Upregulation of long noncoding RNA zinc finger antisense 1 enhances epithelial-mesenchymal transition in vitro and predicts poor prognosis in glioma

Increasing evidence indicates that long noncoding RNAs play important roles in development and progression of various cancers. Zinc finger antisense 1 is a novel long noncoding RNA whose clinical significance, biological function, and underlying mechanism are still undetermined in glioma. In this study, we reported that zinc finger antisense 1 expression was markedly upregulated in glioma and tightly correlated with clinical stage. Moreover, patients with high zinc finger antisense 1 expression had shorter survival. Multivariate Cox regression analysis provided a clue that, probably, zinc finger antisense 1 level could serve as an independent prognostic factor for glioma. Functionally, zinc finger antisense 1 acted as an oncogene in glioma because its knockdown could promote apoptosis and significantly inhibit cell proliferation, migration, and invasion. Furthermore, zinc finger antisense 1 silencing could result in cell cycle arrest at the G0/G1 phase and correspondingly decrease the percentage of S phase cells in both U87 and U251 cell lines. Moreover, it was found that silenced zinc finger antisense 1 could impair migration and invasion by inhibiting the epithelial-mesenchymal transition through reducing the expression of MMP2, MMP9, N-cadherin, Integrin β1, ZEB1, Twist, and Snail as well as increasing E-cadherin level in glioma. Taken together, our data identified that zinc finger antisense 1 might act as a valuable prognostic biomarker and potential therapeutic target for glioma.

LncRNA CCAT1 modulates the sensitivity of paclitaxel in nasopharynx cancers cells via miR-181a/CPEB2 axis

Recent studies reported that long non-coding RNA (lncRNA) might play critical roles in regulating chemo-resistant of multiple types of cancer. This study aimed to investigate whether long non-coding RNA CCAT1 was involved in Paclitaxel resistance in nasopharyngeal carcinoma (NPC). qRT-PCR was used for testing the expression of CCAT1, miR-181a and CPEB2 in tumor tissues and NPC cancers. NPC cells were transfected with siRNAs to suppress the mRNA level of CCAT1 in NPC cells. MTT assays and flow cytometry analysis were used to assess the sensitivity of paclitaxel in NPC cells. Luciferase reporter assays were used to examine the interaction of CCAT1 or CPEB2 to miR-181a. Our findings revealed that the upregulated CCAT1 results in significantly enhancing paclitaxel resistance in nasopharyngeal cancer cells. Bioinformatics analysis and luciferase reporter assay indicated that the upregulated CCAT1 sponges miR-181a in NPC cells. Furthermore, RNA immuno-precipitation assays showed that miR-181a could directly bind to CCAT1 mRNA in NPC cells. We restored miR-181a in NPC cells, and found restoration of miR-181a re-sensitized the NPC cells to paclitaxel in vitro. In addition, our results also showed that miR-181a was a modulator of paclitaxel sensitivity due to its regulative effect on cell apoptosis via targeting CPEB2 in NPC cells. Taken together, lncRNA CCAT1 regulates the sensitivity of paclitaxel in NPC cells via miR-181a/CPEB2 axis.

Long non-coding RNA CCAT1 is overexpressed in oral squamous cell carcinomas and predicts poor prognosis

Oral squamous cell carcinoma (SCC) is the most common malignant tumor in India with 5-year survival rates totaling <50%. Recently, dysregulation of non-coding RNA was reported as a potential hallmark of carcinogenesis. Colon Cancer Associated Transcript 1 (CCAT1), an lncRNA located in chromosome 8q24, close to the c-Myc gene, has been reported to be overexpressed in many human cancers. In the present study, the authors analyzed the expression of CCAT1, c-Myc and the miRNAs miR155-5p, let7b-5p, miR490-3p and miR218-5p sponged by CCAT1 in 60 oral tumor and 8 normal tissue samples by reverse transcription-quantitative polymerase chain reaction. CCAT1 was significantly overexpressed in 27% (16/60) of oral tumors. Interestingly, a high level of c-Myc expression was observed in all CCAT1 overexpressing cases (P=0.0473). Furthermore, CCAT1 overexpression significantly downregulated miR155-5p (P=0.03) and let7b-5p (P<0.0001). Oral cancer cases expressing high level of CCAT1 (P=0.01) presented poor therapeutic outcome. To the best of the authors' knowledge, this is the first study to report the overexpression of the CCAT1 in oral SCCs, and the results suggested that CCAT1 overexpression may sponge miR155-5p and let7b-5p, and may account for poor treatment response.

LncRNAs: From Basic Research to Medical Application

This review aimed to summarize the current research contents about long noncoding RNAs (lncRNAs) and some related lncRNAs as molecular biomarkers or therapy strategies in human cancer and cardiovascular diseases. Following the development of various kinds of sequencing technologies, lncRNAs have become one of the most unknown areas that need to be explored. First, the definition and classification of lncRNAs were constantly amended and supplemented because of their complexity and diversity. Second, several methods and strategies have been developed to study the characteristic of lncRNAs, including new species identifications, subcellular localization, gain or loss of function, molecular interaction, and bioinformatics analysis. Third, based on the present results from basic researches, the working mechanisms of lncRNAs were proved to be different forms of interactions involving DNAs, RNAs, and proteins. Fourth, lncRNA can play different important roles during the embryogenesis and organ differentiations. Finally, because of the tissue-specific expression of lncRNAs, they could be used as biomarkers or therapy targets and effectively applied in different kinds of diseases, such as human cancer and cardiovascular diseases.

Long noncoding RNAs: pivotal regulators in acute myeloid leukemia

Long noncoding RNAs (lncRNAs) have emerged as a class of pivotal regulators of gene expression. Recent studies have shown that lncRNAs contribute to the initiation, maintenance, and development of acute myeloid leukemia (AML). In this review, we summarize the current knowledge of the lncRNAs that play critical roles in AML. We first briefly describe the characteristics of lncRNAs, and then focus on their regulatory roles in AML, including the modulation of differentiation, proliferation, cell cycle, and apoptosis. We further emphasize the action of lncRNAs during leukemogenesis by describing how they interact with RNA, protein and chromatin DNA to exert their functions. We also highlight an urgent need to investigate the mechanisms by which lncRNAs contribute to the pathogenesis of AML. Finally, we discuss the prognostic value of lncRNAs in AML patients.

The lncRNA SNHG5/miR-32 axis regulates gastric cancer cell proliferation and migration by targeting KLF4

Long noncoding RNAs (lncRNAs) are emerging as important regulators in cellular processes, including the development, proliferation, and migration of cancer cells. We have demonstrated in a prior study that small nucleolar RNA host gene 5 (SNHG5) is dysregulated in gastric cancer (GC). To further explore the underlying mechanisms of SNGH5 function in the development of GC, in this study, we screened the microRNAs interacting with SNHG5 and elucidated their roles in GC. We showed that SNHG5 contains a putative miR-32-binding site and that deletion of this site abolishes the responsiveness to miR-32. Suppression of SNHG5 expression by miR-32 was found to be Argonaute (Ago)2-dependent. Immunoprecipitation showed that SNHG5 could be pulled down from the Ago-2 complex with miR-32. Furthermore, it was reported that Kruppel-like factor 4 (KLF4) is a target gene of miR-32. In agreement with SNHG5 being a decoy for miR-32, we showed that KLF4 suppression by miR-32 could be partially rescued by SNHG5 overexpression, whereas miR-32 mimic rescued SNHG5 overexpression-mediated suppression of GC cell migration. In addition, we identified a negative correlation between the expression of SNHG5 and miR-32 in GC tissues. Furthermore, KLF4 expression was significantly downregulated in GC specimens, and a negative correlation between miR-32 and KLF4 expression and a positive correlation between KLF4 and SNHG5 expression levels were detected. Overall, this study demonstrated, for the first time, that the SNHG5/miR-32/KLF4 axis functions as an important player in GC cell migration and potentially contributes to the improvement of GC diagnosis and therapy.-Zhao, L., Han, T., Li, Y., Sun, J., Zhang, S., Liu, Y., Shan, B., Zheng D., Shi, J. The lncRNA SNHG5/miR-32 axis regulates gastric cancer cell proliferation and migration by targeting KLF4.

LncRNA AK015322 promotes proliferation of spermatogonial stem cell C18-4 by acting as a decoy for microRNA-19b-3p

Long noncoding RNAs (lncRNAs) have been reported to play important roles in male reproduction. In our previous research, we studied the expression profile of lncRNAs in mouse male germ cells including spermatogonial stem cell, type A spermatogonia, pachytene spermatocyte, and round spermatid by microarray method, which showed that testis-enriched lncRNA AK015322 is highly expressed in spermatogonial stem cell. In this study, we found that AK015322 promotes proliferation of mouse spermatogonial stem cell line C18-4 in vitro. Furthermore, bioinformatic analysis, real-time PCR, and luciferase assay validated that AK015322 serves as a decoy of microRNA-19b-3p (miR-19b-3p), antagonizes its function, and attenuates the repression of its endogenous target transcriptional factor Ets-variant 5 (ETV5) which was a pivotal gene for spermatogonial stem cell self-renewal. Taken together, our results suggest that a variety of lncRNAs may regulate male reproduction through serving as competing-endogenous RNAs to modulate the function of germ cells.

Identification of lncRNA functions in lung cancer based on associated protein-protein interaction modules

Long non-coding RNAs (lncRNAs) have been found to play important roles in various biological processes; however, many of their functions remain unclear. In this study, we present a novel approach to identify the lncRNA-associated protein-protein interaction (PPI) modules and ascertain their functions in human lung squamous cell carcinoma. We collected lncRNA and mRNA expression profiles of lung squamous cell carcinoma from The Cancer Genome Atlas. To identify the lncRNA-associated PPI modules, lncRNA-mRNA co-expression networks were first constructed based on the mutual ranks of expression correlations. Next, we examined whether the co-expressed mRNAs of a specific lncRNA were closely connected by PPIs. For this, a significantly connected mRNA set was considered to be the lncRNA-associated PPI module. Finally, the prospective functions of a lncRNA was inferred using Gene Ontology enrichment analysis on the associated module. We found that lncRNA-associated PPI modules were subtype-dependent and each subtype had unique molecular mechanisms. In addition, antisense lncRNAs and sense genes tended to be functionally associated. Our results might provide new directions for understanding lncRNA regulations in lung cancer. The analysis pipeline was implemented in a web tool, available at http://lncin.ym.edu.tw/.

CCAT1: an oncogenic long noncoding RNA in human cancers

PURPOSE

Long noncoding RNAs (lncRNAs) are a new class of noncoding RNAs that participate in a variety of biological processes such as cell proliferation, cell cycle, differentiation and apoptosis, mainly by regulation of gene expression at various levels, including chromatin, splicing, transcriptional and post-transcriptional levels. CCAT1 is a recently identified oncogenic lncRNA, which has been reported to be consistently upregulated in multiple cancer tissues and closely correlated with initiation and progression of cancers. The aim of this paper is to provide an overview of various roles of CCAT1 in human cancers.

METHODS AND RESULTS

We searched studies in electronic databases. Studies have shown the high expression pattern and oncogenic role of CCAT1 in different types of cancer, and aberrant expression of CCAT1 is involved in several processes correlated with carcinogenesis such as cell proliferation, apoptosis, migration and invasion by regulating different target genes and pathways.

CONCLUSION

LncRNA CCAT1 promises to be a novel diagnostic biomarker, therapeutic target, as well as prognostic biomarker in human cancers.