Overexpression of the long non-coding RNA SPRY4-IT1 promotes tumor cell proliferation and invasion by activating EZH2 in hepatocellular carcinoma

Microarray‑based bioinformatics analysis of the prospective target gene network of key miRNAs influenced by long non‑coding RNA PVT1 in HCC

The long non-coding RNA (lncRNA) PVT1 plays vital roles in the tumorigenesis and development of various types of cancer. However, the potential expression profiling, functions and pathways of PVT1 in HCC remain unknown. PVT1 was knocked down in SMMC-7721 cells, and a miRNA microarray analysis was performed to detect the differentially expressed miRNAs. Twelve target prediction algorithms were used to predict the underlying targets of these differentially expressed miRNAs. Bioinformatics analysis was performed to explore the underlying functions, pathways and networks of the targeted genes. Furthermore, the relationship between PVT1 and the clinical parameters in HCC was confirmed based on the original data in the TCGA database. Among the differentially expressed miRNAs, the top two upregulated and downregulated miRNAs were selected for further analysis based on the false discovery rate (FDR), fold-change (FC) and P-values. Based on the TCGA database, PVT1 was obviously highly expressed in HCC, and a statistically higher PVT1 expression was found for sex (male), ethnicity (Asian) and pathological grade (G3+G4) compared to the control groups (P<0.05). Furthermore, Gene Ontology (GO) analysis revealed that the target genes were involved in complex cellular pathways, such as the macromolecule biosynthetic process, compound metabolic process, and transcription. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the MAPK and Wnt signaling pathways may be correlated with the regulation of the four candidate miRNAs. The results therefore provide significant information on the differentially expressed miRNAs associated with PVT1 in HCC, and we hypothesized that PVT1 may play vital roles in HCC by regulating different miRNAs or target gene expression (particularly MAPK8) via the MAPK or Wnt signaling pathways. Thus, further investigation of the molecular mechanism of PVT1 in HCC is needed.

Long non-coding RNAs: crucial regulators of gastrointestinal cancer cell proliferation

Studies of long non-coding RNAs (lncRNAs) have been prevalent in the field of non-coding RNA regulation in recent years. LncRNAs exert crucial effects on malignant cell processes in the gastrointestinal system, including proliferation. Aberrant lncRNA expression, through both oncogenes and tumor suppressor genes, is instrumental to tumor cell proliferation. Here, we summarize the different molecular mechanisms and relevant signaling pathways through which multifarious lncRNAs regulate cell proliferation and we show that lncRNAs are potential biomarkers for gastrointestinal cancers.

The Role of Circulating Free DNA and MicroRNA in Non-Invasive Diagnosis of HBV- and HCV-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the third and the fifth leading cause of cancer related death worldwide in men and in women, respectively. HCC generally has a poor prognosis, with a very low 5-year overall survival, due to delayed diagnosis and treatment. Early tumour detection and timely intervention are the best strategies to reduce morbidity and mortality in HCC patients. Histological evaluation of liver biopsies is the gold standard for cancer diagnosis, although it is an invasive, time-consuming and expensive procedure. Recently, the analysis of circulating free DNA (cfDNA) and RNA molecules released by tumour cells in body fluids, such as blood serum, saliva and urine, has attracted great interest for development of diagnostic assays based on circulating liver cancer molecular biomarkers. Such "liquid biopsies" have shown to be useful for the identification of specific molecular signatures in nucleic acids released by cancer cells, such as gene mutations and altered methylation of DNA as well as variations in the levels of circulating microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Body fluids analysis may represent a valuable strategy to monitor liver disease progression in subjects chronically infected with hepatitis viruses or cancer relapse in HCC treated patients. Several studies showed that qualitative and quantitative assays evaluating molecular profiles of circulating cell-free nucleic acids could be successfully employed for early diagnosis and therapeutic management of HCC patients. This review describes the state of art on the use of liquid biopsy for cancer driver gene mutations, deregulated DNA methylation as well as miRNA levels in HCC diagnosis.

Upregulated long non-coding RNA SPRY4-IT1 predicts dismal prognosis for pancreatic ductal adenocarcinoma and regulates cell proliferation and apoptosis

Recently, long noncoding RNAs (lncRNAs) have been emerged as pivotal regulators in various human cancers, including pancreatic ductal adenocarcinoma (PDAC). SPRY4-intronic transcript 1 (SPRY4-IT1) was reported to be upregulated in some kind of human cancers. Here, we elucidated the biological functions and possible clinical values of SPRY4-IT1 on PDAC. In present study, expression of SPRY4-IT1 in PDAC tissues and corresponding normal tissues were explored by qRT-PCR experiments. The link between SPRY4-IT1 expression levels and clinicopathological significance was further analyzed. In addition, the oncogenic role of SPRY4-IT1 was detected both in vitro and in vivo. The results demonstrated that SPRY4-IT1 was abnormally upregulated in PDAC tissues and cell lines. Tumor stage and differentiation grade was closely correlated with SPRY4-IT1 expression. Additionally, decreased SPRY4-IT1 contributed to tumor suppressive effect through attenuating cell growth, clonogenic ability and facilitating apoptosis via Bcl-2/caspase-3 pathway in PANC1 and Capan-2 cells. Furthermore, the xenograft study confirmed the tumor proliferation-promoting role of SPRY4-IT1 in PANC1 cells. Taken together, these findings indicated that SPRY4-IT1 is a potential therapeutic target and prognosis biomarker for the patients with PDAC.

Downregulation of the long non-coding RNA ZFAS1 is associated with cell proliferation, migration and invasion in breast cancer

Long non-coding RNAs (lncRNAs) are non-coding RNAs that are >200 nucleotides in length. Recent studies have identified a number of lncRNAs with critical roles in various biological processes including tumorigenesis. Zinc finger antisense 1 (ZFAS1) is a lncRNA that has recently been reported to be involved in the progression of several human cancers. However, the biological function of ZFAS1 in breast cancer remains to be elucidated. In order to determine the effect of ZFAS1 in breast cancer cells, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to measure ZFAS1 expression in cells from breast cancer cell lines. In addition, gain-of-function experiments were performed in vitro to investigate the biological role of ZFAS1. The results revealed that ZFAS1 expression was significantly downregulated in breast cancer cell lines when compared with the levels in controls. In vitro experiments also demonstrated that ZFAS1 overexpression significantly suppressed cell proliferation by causing cell cycle arrest and inducing apoptosis in breast cancer cells. Further functional assays indicated that ZFAS1 overexpression inhibited cell migration and invasion by regulating epithelial-mesenchymal transition. These findings indicated that the lncRNA ZFAS1 may be a tumor suppressor in breast cancer, and thus, may serve as a potential therapeutic target for patients with breast cancer.

Non-coding RNAs in hepatocellular carcinoma: molecular functions and pathological implications

Hepatocellular carcinoma (HCC) is a leading lethal malignancy worldwide. However, the molecular mechanisms underlying liver carcinogenesis remain poorly understood. Over the past two decades, overwhelming evidence has demonstrated the regulatory roles of different classes of non-coding RNAs (ncRNAs) in liver carcinogenesis related to a number of aetiologies, including HBV, HCV and NAFLD. Among the ncRNAs, microRNAs, which belong to a distinct class of small ncRNAs, have been proven to play a crucial role in the post-transcriptional regulation of gene expression. Deregulation of microRNAs has been broadly implicated in the inactivation of tumour-suppressor genes and activation of oncogenes in HCC. Modern high-throughput sequencing analyses have unprecedentedly identified a very large number of non-coding transcripts. Divergent groups of long ncRNAs have been implicated in liver carcinogenesis through interactions with DNA, RNA or proteins. Overall, ncRNAs represent a burgeoning field of cancer research, and we are only beginning to understand the importance and complicity of the ncRNAs in liver carcinogenesis. In this Review, we summarize the common deregulation of small and long ncRNAs in human HCC. We also comprehensively review the pathological roles of ncRNAs in liver carcinogenesis, epithelial-to-mesenchymal transition and HCC metastasis and discuss the potential applications of ncRNAs as diagnostic tools and therapeutic targets in human HCC.

Long non-coding RNA SPRY4-IT1 promotes cell proliferation and invasion by regulation of Cdc20 in pancreatic cancer cells

Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) play a critical role in the development of human cancers including pancreatic cancer. Long non-coding RNA SPRY4-IT1 (sprouty4-intron transcript 1) has been reported to play an oncogenic role in various types of human carcinomas. However, the role of SPRY4-IT1 in pancreatic cancer is unclear. The objective of this study was to determine the function of SPRY4-IT1 on proliferation and invasion in pancreatic cancer. In the current study, we dissected the function and mechanism of SPRY4-IT1 by multiple approaches including Real-time RT-PCR, Western blotting analysis, MTT assay, Wound healing assay, Transwell assay, and transfection. We found that down-regulation of SPRY4-IT1 inhibited cell growth and induced cell apoptosis in pancreatic cancer cells. Moreover, SPRY4-IT1 knockdown induced cell cycle arrest at G0/G1 phase. Furthermore, inhibition of SPRY4-IT1 retarded cell migration and invasion in pancreatic cancer cells. Overexpression of SPRY4-IT1 enhanced cell growth and invasion, and inhibited cell apoptosis in pancreatic cancer cells. Mechanistically, suppression of SPRY4-IT1 inhibited the expression of Cdc20 in pancreatic cancer cells. Our findings demonstrated that inhibition of SPRY4-IT1 could be a potential therapeutic approach for the treatment of pancreatic cancer.

Behind the curtain of non-coding RNAs; long non-coding RNAs regulating hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is one of the most common and aggressive cancers worldwide. HCC is the fifth common malignancy in the world and the second leading cause of cancer death in Asia. Long non-coding RNAs (lncRNAs) are RNAs with a length greater than 200 nucleotides that do not encode proteins. lncRNAs can regulate gene expression and protein synthesis in several ways by interacting with DNA, RNA and proteins in a sequence specific manner. They could regulate cellular and developmental processes through either gene inhibition or gene activation. Many studies have shown that dysregulation of lncRNAs is related to many human diseases such as cardiovascular diseases, genetic disorders, neurological diseases, immune mediated disorders and cancers. However, the study of lncRNAs is challenging as they are poorly conserved between species, their expression levels aren’t as high as that of mRNAs and have great interpatient variations. The study of lncRNAs expression in cancers have been a breakthrough as it unveils potential biomarkers and drug targets for cancer therapy and helps understand the mechanism of pathogenesis. This review discusses many long non-coding RNAs and their contribution in HCC, their role in development, metastasis, and prognosis of HCC and how to regulate and target these lncRNAs as a therapeutic tool in HCC treatment in the future.

Long non-coding RNA CCAT2 promotes cholangiocarcinoma cells migration and invasion by induction of epithelial-to-mesenchymal transition

Cholangiocarcinoma (CCA) is one of the most aggressive malignancies in humans. Emerging evidence has indicated that abnormally expressed long non-coding RNAs (lncRNAs) could conduce to tumorigenesis and progression. Specifically, colon cancer-associated transcript 2 (CCAT2) has been reported to be overexpressed in several carcinomas. However, its clinical significance and functional roles in CCA is still unknown. qRT-PCR experiments were conducted to assess the CCAT2 expression in CCA tissue samples and cell lines. In addition, the link between CCAT2 expression and clinicopathological characteristics was analyzed. The potential effects of CCAT2 in CCA cells was evaluated in vitro including cell proliferation, colony-forming ability, apoptosis, migration, invasion and epithelial-to-mesenchymal transition (EMT). As a result, CCAT2 was aberrantly overexpressed in CCA tissue samples and cells, and this upregulation was correlated with tumor size, lymph node invasion, TNM stage and postoperative recurrence in CCA patients. Overexpression of CCAT2 could serve as an independent prognostic indicator for CCA. Additionally, overexpression of CCAT2 was a dismal prognostic indicator for patients with CCA. Furthermore, CCAT2 silencing caused tumor suppressive effects via reducing cell proliferation, migration and invasion, inducing cell apoptosis and reversing the EMT process in HuCCT1 and CCLP1 cells. Collectively, our data illustrated that lncRNA CCAT2 played an oncogenic role in CCA and may offer a potential therapeutic target for treating this fatal disease.

LncRNA SPRY4-IT was concerned with the poor prognosis and contributed to the progression of thyroid cancer

Long non-coding RNAs (lncRNAs) have been demonstrated to be critical regulators in tumorigenesis. LncRNA SPRY4-IT1 has been identified as critical regulator for hepatocellular carcinoma and ovarian cancer. However, the potential role and clinical value of SPRY4-IT1 in human thyroid cancer (TC) still remain unclear and need to be uncovered. Our current study was aimed to ascertain the biological role of expression of SPRY4-IT1 in TC tissues and cells. Our findings revealed that the level of SPRY4-IT1 was significantly upregulated in TC tissues and cell lines, which was correlated with poor prognosis. And cellular experiments exhibited that silenced SPRY4-IT1 inhibited the proliferative and migratory abilities of TC cells. Mechanism assays noted that silenced SPRY4-IT1 could increase the levels of transforming growth factor-β1 (TGF-β1) and p-Smad2/3 and function mediated by si-SPRY4-IT1 could be rescued by the interference of TGF-β1. Generally speaking, these findings elucidated that SPRY4-IT1 might become a novel prognostic factor in the clinical behaviors of TC patients and participated in the progression of TC through targeting TGF-β/Smad signaling pathway.

Long noncoding RNAs in the initiation, progression, and metastasis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Despite awareness of risk factors for the development of HCC and advances in the diagnosis and clinical management of the disease, the molecular mechanisms underlying hepatocarcinogenesis remain poorly understood. Recent experimental studies provide strong evidence that long noncoding RNAs (lncRNAs), non-protein-coding transcripts with lengths >200 basepairs, contribute to the pathogenesis of numerous human diseases. Over the past decade, a role for lncRNAs in the initiation, progression, and metastasis of HCC has likewise emerged and developed into a highly active area of research. Although many lncRNAs appear to be dysregulated in HCC, extensive functional characterization has been performed on only a small proportion of these candidates to date. This review summarizes select lncRNAs that have been shown to wield functional relevance in the initiation, progression, or metastasis of HCC, focusing on the specific mechanisms by which lncRNA effects might be linked to clinical manifestations of the disease. In addition, an overview of circulating lncRNAs that have been identified as potential biomarkers for the diagnosis and prognosis of HCC is provided.

Dysregulated long noncoding RNAs (lncRNAs) in hepatocellular carcinoma: implications for tumorigenesis, disease progression, and liver cancer stem cells

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours with a poor prognosis worldwide. While early stage tumours can be treated with curative approaches such as liver transplantation or surgical resection, these are only suitable for a minority of patients. Those with advanced stage disease are only suitable for supportive approaches and most are resistant to the conventional chemotherapy or radiotherapy. Liver cancer stem cells (LCSCs) are a small subset of cancer cells with unlimited differentiation ability and tumour forming potential. In order to develop novel therapeutic approaches for HCC, we need to understand how the cancer develops and why treatment resistance occurs. Using high-throughput sequencing techniques, a large number of dysregulated long noncoding RNAs (lncRNAs) have been identified, and some of which are closely linked to key aspects of liver cancer pathology, progression, outcomes and for the maintenance of cancer stem cell-like properties. In addition, some lncRNAs are potential biomarkers for HCC diagnosis and may serve as the therapeutic targets. This review summarizes data recently reported lncRNAs that might be critical for the maintenance of the biological properties of LCSCs.

Long non‑coding RNA HOTTIP promotes hepatocellular carcinoma tumorigenesis and development: A comprehensive investigation based on bioinformatics, qRT‑PCR and meta‑analysis of 393 cases

HOTTIP functions as an independent biomarker in multiple cancers. However, the role of HOTTIP in hepatocellular carcinoma (HCC) remains unclear. In this study, we sought to investigate the HOTTIP expression in HCC and normal liver. We combined quantitative reverse transcription-polymerase chain reactions (qRT-PCR), Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA), Multi Experiment Matrix (MEM) and Oncomine database to assess the clinical role and the potential molecular mechanism of HOTTIP in HCC. Furthermore, a meta-analysis was performed to evaluate the relationship between HOTTIP and HCC tumorigenesis and development. Additionally, bioinformatics analysis, which contained Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and network analysis, were applied to investigate the underlying functions, pathways and networks of the potential genes. HOTTIP was obviously upregulated in HCC. A statistically significant higher expression of HOTTIP was found in TNM (III +IV), age (≥60), sex (male), race (white) and cirrhosis (no) compared to the control groups (P<0.05). Furthermore, the meta-analysis of 393 cases from multiple centers indicated that HOTTIP had high diagnostic value in HCC. Additionally, according to GO and KEGG analyses, we found that the most strongly enriched functional terms were gland development, transcription factor activity and extrinsic to membrane. Also, the HOTTIP co-expressed genes were significantly related to PPAR signaling pathway. We speculate that HOTTIP might play a vital part in HCC via regulating various pathways, especially PPAR signaling pathway. However, the detailed mechanism should be confirmed by functional experiments.

Downregulation of the long non-coding RNA TUG1 is associated with cell proliferation, migration, and invasion in breast cancer

Recent studies have identified many long non-coding RNAs (lncRNAs) with critical roles in various biological processes including tumorigenesis. Taurine-upregulated gene 1 (TUG1), is an lncRNA recently reported to be involved in the progression of several human cancers. This study aimed to investigate the clinical significance and biological functions of TUG1 in breast cancer. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to measure TUG1 expression in cells from breast cancer cell lines and in 58 matched pairs of breast cancer and normal tissue samples from patients with clinicopathological comparisons. Gain-and loss-of-function experiments were performed in vitro to investigate the biological role of TUG1. TUG1 expression was significantly downregulated in both breast cancer tissues and cell lines compared to controls, and low TUG1 expression was significantly correlated with mutant p53 expression (p=0.037) and lymph node metastasis (p=0.044). In vitro experiments revealed that TUG1 overexpression significantly suppressed cell proliferation by causing cell cycle arrest and inducing apoptosis in breast cancer cells, while TUG1 knockdown caused increased cell growth via promoting cell cycle progression and regulating the expression of cyclinD1 and CDK4. Further functional assays indicated that TUG1 overexpression significantly promoted cell migration and invasion while TUG1 knockdown had the opposite effects. Our findings indicate that the lncRNA TUG1 is a tumor suppressor in breast cancer, and may serve as a novel prognostic biomarker and potential therapeutic target for patients with breast cancer.

The prognostic value of abnormally expressed lncRNAs in colorectal cancer: A meta-analysis

BACKGROUND

Colorectal cancer (CRC) is the third most prevalent cancer type and the third leading cause of cancer-related deaths worldwide, it is urgently needed to discover a new marker for the progress of CRC. Many long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in CRC, and may be feasible as effective biomarkers and prognostic factors. The aim of this study was to identify the prognostic value of various lncRNAs in CRC.

METHODS

Pubmed, Web of Science, Embase and Cochrane Library were searched for potentially related studies. A total of 34 eligible studies including 30 on overall survival (OS), 7 on disease-free survival (DFS), 1 on relapse-free survival (RFS), 2 on disease-specific survival (DSS) and 29 on clinicopathological features were qualified from the databases.

RESULTS

The results showed that the expression levels of lncRNAs were significantly associated with poor OS (hazard ratio (HR) = 2.08, 95% confidence interval (CI) = 1.68-2.57, P<0.001, I2 = 70%), DFS (HR = 1.79, 95% CI = 1.54-2.08, P<0.001, I2 = 6%) and DSS (HR = 0.11, 95% CI = 0.02-0.54, P = 0.007, I2 = 14%). Subgroup analysis further showed that lncRNA transcription level was significantly associated with tumor differentiation (odds ratio (OR) = 0.51, 95% CI = 0.34-0.77, P = 0.001), lymph node metastasis (OR = 1.63, 95% CI = 1.23-2.17, P = 0.0007), distant metastasis (OR = 2.06, 95% CI = 1.29-3.30, P = 0.002), TNM stage (OR = 0.44, 95% CI = 0.32-0.62, P<0.001), tumor invasion depth (OR = 0.48, 95% CI = 0.39-0.60, P<0.001).

CONCLUSIONS

The meta-analysis demonstrated that abnormal lncRNA transcription level may serve as a promising indicator for prognostic of patients with CRC.

SPRY4-IT1: A novel oncogenic long non-coding RNA in human cancers

Long non-coding RNAs are classified as a kind of RNA, which are longer than 200 nucleotides in length and cannot be translated into proteins. Multiple studies have demonstrated that long non-coding RNAs are involved in various cellular processes, including proliferation, differentiation, cell death, and metastasis. Among numerous long non-coding RNAs, we focus on Sprouty4-Intron 1 (SPRY4-IT1), a well-known long non-coding RNA that is overexpressed in various kinds of tumor tissues and cell lines. Accumulating evidences show that SPRY4-IT1 was dysregulated in various cancers, including melanoma, breast cancer, esophageal squamous cell carcinoma, non-small cell lung cancer, gastric cancer, colon cancer, and hepatocellular carcinoma, and amplification of SPRY4-IT1 was associated with different clinicopathological features of cancer patients. Importantly, SPRY4-IT1 exerts important roles in tumor progression and metastasis. However, detailed molecular mechanisms of SPRY4-IT1 in cancer progression and metastasis were poorly understood. In this review, we have focused on the characteristics of SPRY4-IT1 and illustrated the biological function and mechanism of SPRY4-IT1 in cancer development.

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.