Long non-coding RNA HOTTIP is frequently up-regulated in hepatocellular carcinoma and is targeted by tumour suppressive miR-125b

Exploring non-coding RNA mechanisms in hepatocellular carcinoma: implications for therapy and prognosis

Hepatocellular carcinoma (HCC) is a significant contributor to cancer-related deaths in the world. The development and progression of HCC are closely correlated with the abnormal regulation of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Important biological pathways in cancer biology, such as cell proliferation, death, and metastasis, are impacted by these ncRNAs, which modulate gene expression. The abnormal expression of non-coding RNAs in HCC raises the possibility that they could be applied as new biomarkers for diagnosis, prognosis, and treatment targets. Furthermore, by controlling the expression of cancer-related genes, miRNAs can function as either tumor suppressors or oncogenes. On the other hand, lncRNAs play a role in the advancement of cancer by interacting with other molecules within the cell, which, in turn, affects processes such as chromatin remodeling, transcription, and post-transcriptional processes. The importance of ncRNA-driven regulatory systems in HCC is being highlighted by current research, which sheds light on tumor behavior and therapy response. This research highlights the great potential of ncRNAs to improve patient outcomes in this difficult disease landscape by augmenting the present methods of HCC care through the use of precision medicine approaches.

Noncoding RNAs and programmed cell death in hepatocellular carcinoma: Significant role of epigenetic modifications in prognosis, chemoresistance, and tumor recurrence rate

Hepatocellular carcinoma (HCC) is the most common type of liver cancer with a high death rate in the world. The molecular mechanisms related to the pathogenesis of HCC have not been precisely defined so far. Hence, this review aimed to address the potential cross-talk between noncoding RNAs (ncRNAs) and programmed cell death in HCC. All related papers in the English language up to June 2023 were collected and screened. The searched keywords in scientific databases, including Scopus, PubMed, and Google Scholar, were HCC, ncRNAs, Epigenetic, Programmed cell death, Autophagy, Apoptosis, Ferroptosis, Chemoresistance, Tumor recurrence, Prognosis, and Prediction. According to the reports, ncRNAs, comprising long ncRNAs, microRNAs, circular RNAs, and small nucleolar RNAs can affect cell proliferation, migration, invasion, and metastasis, as well as cell death-related processes, such as autophagy, ferroptosis, necroptosis, and apoptosis in HCC by regulating cancer-associated genes and signaling pathways, for example, phosphoinositide 3-kinase/Akt, extracellular signal-regulated kinase/MAPK, and Wnt/β-catenin signaling pathways. It seems that ncRNAs, as epigenetic regulators, can be utilized as biomarkers in diagnosis, prognosis, survival and recurrence rates prediction, chemoresistance, and evaluation of therapeutic response in HCC patients. However, more scientific evidence is suggested to be accomplished to confirm these results.

Targeting non-coding RNAs and N6-methyladenosine modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common form of primary liver cancers, accounts for a significant portion of cancer-related death globally. However, the molecular mechanisms driving the onset and progression of HCC are still not fully understood. Emerging evidence has indicated that non-protein-coding regions of genomes could give rise to transcripts, termed non-coding RNA (ncRNA), forming novel functional driving force for aberrant cellular activity. Over the past decades, overwhelming evidence has denoted involvement of a complex array of molecular function of ncRNAs at different stages of HCC tumorigenesis and progression. In this context, several pre-clinical studies have highlighted the potentials of ncRNAs as novel therapeutic modalities in the management of human HCC. Moreover, N6-methyladenosine (m6A) modification, the most prevalent form of internal mRNA modifications in mammalian cells, is essential for the governance of biological processes within cells. Dysregulation of m6A in ncRNAs has been implicated in human carcinogenesis, including HCC. In this review, we will discuss dysregulation of several hallmark ncRNAs (miRNAs, lncRNAs, and circRNAs) in HCC and address the latest advances for their involvement in the onset and progression of HCC. We also focus on dysregulation of m6A modification and various m6A regulators in the etiology of HCC. In the end, we discussed the contemporary preclinical and clinical application of ncRNA-based and m6A-targeted therapies in HCC.

Functionalized Carbon Nanotubes for Delivery of Ferulic Acid and Diosgenin Anticancer Natural Agents

It was investigated whether loading multi-wall carbon nanotubes (CNTs) with two natural anticancer agents: ferulic acid (FUA) and diosgenin (DGN), may enhance the anticancer effect of these drugs. The CNTs were functionalized with carboxylic acid (CNTCOOH) or amine (CNTNH2), loaded with the above pro-drugs, as well as both combined and coated with chitosan or chitosan-stearic acid. Following physicochemical characterization, the drug-loading properties and kinetics of the drug's release were investigated. Their effects on normal human skin fibroblasts and MCF-7 breast carcinoma cells, HepG2 hepatocellular carcinoma cells, and A549 non-small-cell lung cancer cells were evaluated in vitro. Their actions at the molecular level were evaluated by assessing the expression of lncRNAs (HULC, HOTAIR, CCAT-2, H19, and HOTTIP), microRNAs (mir-21, mir-92, mir-145, and mir-181a), and proteins (TGF-β and E-cadherin) in HepG2 cells. The release of both pro-drugs depended on the glutathione concentration, coating, and functionalization. Release occurred in two stages: a no-burst/zero-order release followed by a sustained release best fitted to Korsmeyer-Peppas kinetics. The combined nanoformulation cancer inhibition effect on HepG2 cancer cells was more pronounced than for A549 and MCF7 cells. The combined nanoformulations had an additive impact followed by a synergistic effect, with antagonism demonstrated at high concentrations. The nanoformulation coated with chitosan and stearic acid was particularly successful in targeting HepG2 cells and inducing apoptosis. The CNT functionalized with carboxylic acid (CNTCOOH), loaded with both FUA and DGN, and coated with chitosan-stearic acid inhibited the expression of lncRNAs and modulated both microRNAs and proteins. Thus, nanoformulations composed of functionalized CNTs dual-loaded with FUA and DGN and coated with chitosan-stearic acid are a promising drug delivery system that enhances the activity of natural pro-drugs.

The role of long non-coding RNA in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent liver malignancy with complex etiology and generally poor prognosis. Recently, long non-coding RNAs (lncRNAs), non-protein-coding RNA molecules exceeding 200 nucleotides, have emerged as pivotal players in HCC, influencing its initiation, progression, invasion, and metastasis. These lncRNAs modulate gene expression at epigenetic, transcriptional, and post-transcriptional levels, actively participating in the pathological and physiological processes of HCC. Understanding the intricate relationship between lncRNAs and HCC is important for improving prognosis and reducing mortality. This review summarizes advancements in elucidating the role of lncRNAs in HCC pathogenesis.

A Survey of Computational Methods and Databases for lncRNA-MiRNA Interaction Prediction

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are two prevalent non-coding RNAs in current research. They play critical regulatory roles in the life processes of animals and plants. Studies have shown that lncRNAs can interact with miRNAs to participate in post-transcriptional regulatory processes, mainly involved in regulating cancer development, metastatic progression, and drug resistance. Additionally, these interactions have significant effects on plant growth, development, and responses to biotic and abiotic stresses. Deciphering the potential relationships between lncRNAs and miRNAs may provide new insights into our understanding of the biological functions of lncRNAs and miRNAs, and the pathogenesis of complex diseases. In contrast, gathering information on lncRNA-miRNA interactions (LMIs) through biological experiments is expensive and time-consuming. With the accumulation of multi-omics data, computational models are extremely attractive in systematically exploring potential LMIs. To the best of our knowledge, this is the first comprehensive review of computational methods for identifying LMIs. Specifically, we first summarized the available public databases for predicting animal and plant LMIs. Second, we comprehensively reviewed the computational methods for predicting LMIs and classified them into two categories, including network-based methods and sequence-based methods. Third, we analyzed the standard evaluation methods and metrics used in LMI prediction. Finally, we pointed out some problems in the current study and discuss future research directions. Relevant databases and the latest advances in LMI prediction are summarized in a GitHub repository https://github.com/sheng-n/lncRNA-miRNA-interaction-methods, and we'll keep it updated.

Decoding hepatocarcinogenesis from a noncoding RNAs perspective

Being a leading lethal malignancy worldwide, the pathophysiology of hepatocellular carcinoma (HCC) has gained a lot of interest. Yet, underlying mechanistic basis of the liver tumorigenesis is poorly understood. The role of some coding genes and their respective translated proteins, then later on, some noncoding RNAs (ncRNAs) such as microRNAs have been extensively studied in context of HCC pathophysiology; however, the implication of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) in HCC is indeed less investigated. As a subclass of the ncRNAs which has been elusive for long time ago, lncRNAs was found to be involved in plentiful cellular functions such as DNA, RNA, and proteins regulation. Hence, it is undisputed that lncRNAs dysregulation profoundly contributes to HCC via diverse etiologies. Accordingly, lncRNAs represent a hot research topic that requires prime focus in HCC. In this review, the authors discuss breakthrough discoveries involving lncRNAs and circRNAs dysregulation that have contributed to the contemporary concepts of HCC pathophysiology and how these concepts could be leveraged as potential novel diagnostic and prognostic HCC biomarkers. Further, this review article sheds light on future trends, thereby discussing the pathological roles of lncRNAs and circRNAs in HCC proliferation, migration, and epithelial-to-mesenchymal transition. Along this line of reasoning, future recommendations of how these targets could be exploited to achieve effective HCC-related drug development is highlighted.

Comprehensive analysis of lncRNA-mediated ceRNA networkfor hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is a high-burden cancer. The molecular mechanism of HCC has not been fully elucidated. Notably, current research has revealed a significant function for long non-coding RNAs (lncRNAs) in the prognosis of patients with HCC. Here, this study aims to construct a regulated lncRNA-mediated ceRNA network and find biological targets for the treatment of HCC.

Methods

Based on the RNA expression patterns from the TCGA, we did an analysis to determine which genes were expressed differently between liver tumor tissues and noncancerous tissues. Then, using bioinformatic tools, we built a lncRNA-miRNA-mRNA ceRNA network and used GO and KEGG functional analyses on the DEmRNAs connected to ceRNA networks. The main lncRNAs in the subnetwork were chosen, and we next looked at the relationships between these lncRNAs and the clinical characteristics of patients with HCC. The prognosis-related genes and immune cells were identified using Kaplan-Meier and Cox proportional hazard analyses, and CIBERSORT was utilized to separate the 22 immune cell types. CCK8 assay was performed to measure cell viability in HCC cells after lncRNA HOTTIP modulation.

Results

Differentially expressed mRNA and lncRNAs in HCC and paracancerous tissues were identified. There are 245 lncRNAs, 126 miRNAs, and 1980 mRNAs that are expressed differently in liver tumour tissues than in noncancerous cells. Function analysis showed that mRNAs in ceRNA network were significantly enriched in G1/S transition of mototiv cell cycle, positive regulation of cell cycle process, hepatocellular carcinoma, and cancer related pathways. CD8 T cells and T follicular helper cells had a favourable link with a 0.65 correlation coefficient. Additionally, there was a strong correlation between Eosinophils, activated NK cells, and B memory cells. Strikingly, depletion of lncRNA HOTTIP inhibited viability of HCC cells. In addition, miR-205 upregulation suppressed viability of HCC cells, while miR-205 downregulation repressed viability of HCC cells. Notably, miR-205 depletion rescued HOTTIP depletion-mediated suppression of cell viability in HCC.

Conclusion

A ceRNA network was created by examining the lncRNA, miRNA, and mRNA expression profiles of liver tumours from the TCGA database. LncRNA HOTTIP promoted cell viability via inhibition of miR-205 in HCC cells.

Long non-coding RNA HOXB-AS1 is a prognostic marker and promotes hepatocellular carcinoma cells' proliferation and invasion

Long non-coding RNAs (lncRNAs) are broadly transcribed in the genome of human and play critical roles in the progression of multiple diseases. Long non-coding HOXB cluster antisense RNA 1 (HOXB-AS1) is a tumor exciter in various cancers. This study aimed to investigate the involvement of HOXB-AS1 in hepatocellular carcinoma (HCC). In the following study, HOXB-AS1 was unveiled to be highly expressed in HCC tissues as opposed to normal tissues. Silencing of HOXB-AS1 led to the loss of proliferation, migration, and invasiveness of HCC cells, namely Hep3B and Huh7. Moreover, the data showed that expression levels of HOXB-AS1 contribute significantly to the patient's survival rates. Otherwise, HOXB-AS1 levels in the serum of patients proved HOXB-AS1 as a biomarker for analysis and treatment of HCC. In summary, this study highlights HOXB-AS1 as key upregulated lncRNA in HCC which being an oncogene can cause proliferation and metastasis of HCC cells. The results also highlighted HOXB-AS1 as a promising biomarker for early diagnosis and prognosis of patients with HCC.

Noncoding RNAs and their therapeutics in paclitaxel chemotherapy: Mechanisms of initiation, progression, and drug sensitivity

The identification of agents that can reverse drug resistance in cancer chemotherapy, and enhance the overall efficacy is of great interest. Paclitaxel (PTX) belongs to taxane family that exerts an antitumor effect by stabilizing microtubules and inhibiting cell cycle progression. However, PTX resistance often develops in tumors due to the overexpression of drug transporters and tumor-promoting pathways. Noncoding RNAs (ncRNAs) are modulators of many processes in cancer cells, such as apoptosis, migration, differentiation, and angiogenesis. In the present study, we summarize the effects of ncRNAs on PTX chemotherapy. MicroRNAs (miRNAs) can have opposite effects on PTX resistance (stimulation or inhibition) via influencing YES1, SK2, MRP1, and STAT3. Moreover, miRNAs modulate the growth and migration rates of tumor cells in regulating PTX efficacy. PIWI-interacting RNAs, small interfering RNAs, and short-hairpin RNAs are other members of ncRNAs regulating PTX sensitivity of cancer cells. Long noncoding RNAs (LncRNAs) are similar to miRNAs and can modulate PTX resistance/sensitivity by their influence on miRNAs and drug efflux transport. The cytotoxicity of PTX against tumor cells can also be affected by circular RNAs (circRNAs) and limitation is that oncogenic circRNAs have been emphasized and experiments should also focus on onco-suppressor circRNAs.

HOTTIP Mediated Therapy Resistance in Glioma Cells Involves Regulation of EMT-Related miR-10b

The advanced grade glioblastomas are characterized by dismal five-year survival rates and are associated with worse outcomes. Additionally, resistance to therapies is an additional burden responsible for glioma associated mortality. We studied the resistance against temozolomide (TMZ) as a surrogate to understand the mechanism of therapy resistance in glioma cancer cells. Screening of three glioma cells lines, A172, LN229 and SF268 revealed that SF268 glioma cells were particularly resistant to TMZ with the IC-50 of this cell line for TMZ ten times higher than for the other two cell lines. A role of lncRNAs in glioma progression has been identified in recent years and, therefore, we focused on lncRNAs for their role in regulating TMZ resistance in glioma cancer cells. lncRNA HOTTIP was found to be particularly elevated in SF268 cells and over-expression of HOTTIP in both A172 and LN229 remarkably increased their TMZ IC-50s, along with increased cell proliferation, migration, clonogenicity and markers of angiogenesis and metastasis. As a mechanism we observed increased expression of miRNA-10b and mesenchymal markers Zeb1/Zeb2 and reduced expression of E-cadherin in SF268 cells indicating a role of EMT in TMZ resistance. A172 and LN229 cells with overexpressed HOTTIP also had similarly induced EMT and the elevated miR-10b levels. Further, silencing of miR-10b in HOTTIP overexpressing cells as well as the SF268 cells reversed EMT with associated sensitization of all the tested cells to TMZ. Our results thus present a case for HOTTIP in native as well as acquired resistance of glioma cells against chemotherapy, with a key mechanistic role of EMT and the miR-10b. Thus, HOTTIP as well as miR-10b are critical targets for glioma therapy, and need to be tested further.

Liver-specific LINC01146, a promising prognostic indicator, inhibits the malignant phenotype of hepatocellular carcinoma cells both in vitro and in vivo

Background

Long non-coding RNAs (lncRNAs) are involved in the development of hepatocellular carcinoma (HCC). We aimed to investigate the function of LINC01146 in HCC.

Methods

The expression of LINC01146 in HCC tissues was explored via The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and was verified using quantitative real-time polymerase chain reaction (qRT–PCR) in our HCC cohort. Kaplan–Meier analysis was used to assess the relationship between LINC01146 and the prognosis of HCC patients. Cell Counting Kit 8, colony formation assays, Transwell assays, flow cytometric assays, and tumour formation models in nude mice were conducted to reveal the effects of LINC01146 on HCC cells both in vitro and in vivo. Bioinformatic methods were used to explore the possible potential pathways of LINC01146 in HCC.

Results

LINC01146 was significantly decreased in HCC tissues compared with adjacent normal tissues and was found to be related to the clinical presentations of malignancy and the poor prognosis of HCC patients. Overexpression of LINC01146 inhibited the proliferation, migration, and invasion of HCC cells in vitro, while promoting their apoptosis. In contrast, downregulation of LINC01146 exerted the opposite effects on HCC cells in vitro. In addition, overexpression of LINC01146 significantly inhibited tumour growth, while downregulation of LINC01146 promoted tumour growth in vivo. Furthermore, the coexpressed genes of LINC01146 were mainly involved in the “metabolic pathway” and “complement and coagulation cascade pathway”.

Conclusion

LINC01146 expression was found to be decreased in HCC tissues and associated with the prognosis of HCC patients. It may serve as a cancer suppressor and prognostic biomarker in HCC.

High Expression of Long Non-Coding RNA TMCO1-AS1 is Associated With Poor Prognosis of Hepatocellular Carcinoma

Background: The molecular pathways along with the clinical significance of long non-coding RNAs (lncRNAs) in hepatocellular carcinoma (HCC) remain uncertain. Our study sought to identify and characterize lncRNAs associated with HCC.

Methods: LncRNA TMCO1-AS1 was identified by differential expression analysis, receiver operating characteristic (ROC) analysis, and univariate analysis using RNA sequencing and clinical information of HCC from the public database. Then clinical correlations and survival analysis were conducted to further appraise the prognostic significance of lncRNA TMCO1-AS1 in HCC. Hepatoma and adjoining normal tissues from 66 patients who received surgical operation at our center were used to verify the results of the bioinformatics analysis. A survival prognostic model was established combining TMCO1-AS1 expression and other clinical characteristics.

Results: Bioinformatics analysis showed the aberrant high expression of TMCO1-AS1 in HCC tissue. TMCO1-AS1 expression was positively correlated with alpha-fetoprotein (AFP) level, vascular invasion, tumor stage, as well as tumor differentiation. Moreover, survival analysis found a significant inverse association between the expression of TMCO1-AS1 and the survival of patients with HCC. Cox analysis indicated that TMCO1-AS1 was an independent factor for HCC prognosis. Analysis of the HCC tissues from patients at our center provided results similar to those of the bioinformatics analysis. Risk models for overall survival (OS) and recurrence-free survival (RFS) incorporating TMCO1-AS1 exhibited better sensitivity and specificity than using clinical characteristics alone.

Conclusion: High TMCO1-AS1 expression is significantly correlated with the unfavorable poor prognosis of HCC, indicating its potential of being a novel prognostic marker for HCC.

CircRTN4 promotes pancreatic cancer progression through a novel CircRNA-miRNA-lncRNA pathway and stabilizing epithelial-mesenchymal transition protein

BACKGROUND

Circular RNAs (circRNAs) play important roles in many biological processes. However, the detailed mechanism underlying the critical roles of circRNAs in cancer remains largely unexplored. We aim to explore the molecular mechanisms of circRTN4 with critical roles in pancreatic ductal adenocarcinoma (PDAC).

METHODS

CircRTN4 expression level was examined in PDAC primary tumors. The oncogenic roles of circRTN4 in PDAC tumor growth and metastasis were studied in mouse tumor models. Bioinformatics analysis, luciferase assay and miRNA pulldown assay were performed to study the novel circRTN4-miRNA-lncRNA pathway. To identify circRTN4-interacting proteins, we performed circRNA-pulldown and mass spectrometry in PDAC cells. Protein stability assay and 3-Dimensional structure modeling were performed to reveal the role of circRTN4 in stabilizing RAB11FIP1.

RESULTS

CircRTN4 was significantly upregulated in primary tumors from PDAC patients. In vitro and in vivo functional studies revealed that circRTN4 promoted PDAC tumor growth and liver metastasis. Mechanistically, circRTN4 interacted with tumor suppressor miR-497-5p in PDAC cells. CircRTN4 knockdown upregulated miR-497-5p to inhibit the oncogenic lncRNA HOTTIP expression. Furthermore, we identified critical circRTN4-intercting proteins by circRNA-pulldown in PDAC cells. CircRTN4 interacted with important epithelial-mesenchymal transition (EMT)- driver RAB11FIP1 to block its ubiquitination site. We found that circRTN4 knockdown promoted the degradation of RAB11FIP1 by increasing its ubiquitination. Also, circRTN4 knockdown inhibited the expression of RAB11FIP1-regulating EMT-markers Slug, Snai1, Twist, Zeb1 and N-cadherin in PDAC.

CONCLUSION

The upregulated circRTN4 promotes tumor growth and liver metastasis in PDAC through the novel circRTN4-miR-497-5p-HOTTIP pathway. Also, circRTN4 stabilizes RAB11FIP1 to contribute EMT.

The Roles and Mechanisms of lncRNAs in Liver Fibrosis

Long non-coding RNAs (lncRNAs) can potentially regulate all aspects of cellular activity including differentiation and development, metabolism, proliferation, apoptosis, and activation, and benefited from advances in transcriptomic and genomic research techniques and database management technologies, its functions and mechanisms in physiological and pathological states have been widely reported. Liver fibrosis is typically characterized by a reversible wound healing response, often accompanied by an excessive accumulation of extracellular matrix. In recent years, a range of lncRNAs have been investigated and found to be involved in several cellular-level regulatory processes as competing endogenous RNAs (ceRNAs) that play an important role in the development of liver fibrosis. A variety of lncRNAs have also been shown to contribute to the altered cell cycle, proliferation profile associated with the accelerated development of liver fibrosis. This review aims to discuss the functions and mechanisms of lncRNAs in the development and regression of liver fibrosis, to explore the major lncRNAs involved in the signaling pathways regulating liver fibrosis, to elucidate the mechanisms mediated by lncRNA dysregulation and to provide new diagnostic and therapeutic strategies for liver fibrosis.

ceRNAs in Cancer: Mechanism and Functions in a Comprehensive Regulatory Network

Noncoding RNAs have been shown with powerful ability in post-transcriptional regulation, enabling intertwined RNA crosstalk and global molecular interaction in a large amount of dysfunctional conditions including cancer. Competing endogenous RNAs (ceRNAs) are those competitively binding with shared microRNAs (miRNAs), freeing their counterparts from miRNA-induced degradation, thus actively influencing and connecting with each other. Constantly updated analytical approaches boost outstanding advancement achieved in this burgeoning hotspot in multilayered intracellular communication, providing new insights into pathogenesis and clinical treatment. Here, we summarize the mechanisms and correlated factors under this RNA interplay and deregulated transcription profile in neoplasm and tumor progression, underscoring the great significance of ceRNAs for diagnostic values, monitoring biomarkers, and prognosis evaluation in cancer.

Metastatic colorectal cancer: Perspectives on long non-coding RNAs and promising therapeutics

Metastatic colorectal cancer (mCRC) has long been lethal despite the continuous efforts of researchers worldwide to discover and improve therapeutic regimens. Thanks to the emergence of long non-coding RNAs (lncRNAs), which has strongly reshaped our inherent perspectives on the pathophysiological patterns of disease, research in the field has been reinvigorated. Here, we focus on current understanding of the modes of action of lncRNAs, and review their regulatory roles in metastatic colorectal cancer, and discuss correlated potential lncRNA-based therapeutics. All of the discussed studies share clear and promising perspectives on future diagnostic and therapeutic remedies for metastatic colorectal cancer.

The role of miRNA125b in the progression of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common tumours worldwide, and identifying markers related to HCC is an important area of research. As a microRNA (miRNA), miRNA125b (miR-125b) plays an important role in the prediction and prognosis of HCC. In the past 10 years, with increasing research on miR-125b and HCC, the molecular mechanism of its relationship with the development of HCC has been elucidated. MiR-125b inhibits the development of HCC and is highly accurate in predicting HCC and is therefore a valuable predictive marker of HCC. This article summarizes the clinical application of miR-125b in HCC and the potential mechanism of its involvement in the progression of HCC.

Epigenetic Changes Affecting the Development of Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma is a life-threatening disease. Despite many efforts to understand the exact pathogenesis and the signaling pathways involved in its formation, treatment remains unsatisfactory. Currently, an important function in the development of neoplastic diseases and treatment effects is attributed to changes taking place at the epigenetic level. Epigenetic studies revealed modified methylation patterns in HCC, dysfunction of enzymes engaged in the DNA methylation process, the aberrant function of non-coding RNAs, and a set of histone modifications that influence gene expression. The aim of this review is to summarize the current knowledge on the role of epigenetics in the formation of hepatocellular carcinoma.

Abstract

Hepatocellular carcinoma (HCC) remains a serious oncologic issue with still a dismal prognosis. So far, no key molecular mechanism that underlies its pathogenesis has been identified. Recently, by specific molecular approaches, many genetic and epigenetic changes arising during HCC pathogenesis were detected. Epigenetic studies revealed modified methylation patterns in HCC tumors, dysfunction of enzymes engaged in the DNA methylation process, and a set of histone modifications that influence gene expression. HCC cells are also influenced by the disrupted function of non-coding RNAs, such as micro RNAs and long non-coding RNAs. Moreover, a role of liver cancer stem cells in HCC development is becoming evident. The reversibility of epigenetic changes offers the possibility of influencing them and regulating their undesirable effects. All these data can be used not only to identify new therapeutic targets but also to predict treatment response. This review focuses on epigenetic changes in hepatocellular carcinoma and their possible implications in HCC therapy.

Association Between rs1859168/HOTTIP Expression Level and Colorectal Cancer and Adenomatous Polyposis Risk in Egyptians

LncRNA HOTTIP is a new lncRNA that is strictly linked to the susceptibility, growth, propagation, and prognosis of several human cancers together with colorectal cancer. lncRNA HOTTIP rs1859168 may confer colorectal cancer susceptibility through regulating its gene expression level. To elucidate its role in colorectal cancer risk, we genotyped rs1859168 A>C and measured serum HOTTIP expression level in colorectal cancer, adenomatous polyposis patients and controls by real-time polymerase chain reaction. The results displayed that rs1859168 A>C single-nucleotide polymorphism is a risk factor for colorectal cancer among adenomatous polyposis patients and controls, AC versus CC genotypes [adjusted odds ratio (OR) = 2.256, 95% confidence interval (CI) = 1.316-3.868, P = 0.003] when compared with controls and (adjusted OR = 9.521, 95% CI = 3.330-27.217, P < 0.0001) when compared with adenomatous polyposis. Serum HOTTIP was upregulated in the colorectal cancer group when compared with adenomatous polyposis or controls [median (interquartile range) = 3.64 (2.46-5.02) (P < 0.0001)]. A significant difference in serum HOTTIP was found to be associated with different rs1859168 genotypes. rs1859168 A>C and higher serum HOTTIP were significantly associated with distant metastasis, lymph nodes metastasis, and grade III of colorectal cancer. Both rs8159168 and high HOTTIP confer increased risk for colorectal cancer development. [Figure: see text].

Early detection of hepatocellular carcinoma via liquid biopsy: panel of small extracellular vesicle-derived long noncoding RNAs identified as markers

This study investigated the diagnostic potential of serum small extracellular vesicle‐derived long noncoding RNAs (EV‐lncRNAs) for hepatocellular carcinoma (HCC). Driver oncogenic lncRNA candidates were selected by a comparative analysis of lncRNA expression profiles from two whole transcriptome human HCC datasets (Catholic_LIHC and TCGA_LIHC). Expression of selected lncRNAs in serum and small EVs was evaluated using quantitative reverse transcription PCR. Diagnostic power of serum EV‐lncRNAs for HCC was determined in the test (n = 44) and validation (n = 139) cohorts. Of the six promising driver onco‐lncRNAs, DLEU2, HOTTIP, MALAT1, and SNHG1 exhibited favorable performance in the test cohort. In the validation cohort, serum EV‐MALAT1 displayed excellent discriminant ability, while EV‐DLEU2, EV‐HOTTIP, and EV‐SNHG1 showed good discriminant ability between HCC and non‐HCC. Furthermore, a panel combining EV‐MALAT1 and EV‐SNHG1 achieved the best area under the curve (AUC; 0.899, 95% CI = 0.816–0.982) for very early HCC, whereas a panel with EV‐DLEU2 and alpha‐fetoprotein exhibited the best positivity (96%) in very early HCC. Serum small EV‐MALAT1, EV‐DLEU2, EV‐HOTTIP, and EV‐SNHG1 may represent promising diagnostic markers for very early‐stage HCC.

Targeting Long Non-Coding RNAs in Hepatocellular Carcinoma: Progress and Prospects

Hepatocellular carcinoma is the fifth-ranked cancer worldwide with a relatively low five-year survival rate. Long non-coding RNAs are a group of RNAs with remarkable aberrant expression which could act on multiple bioprocesses and ultimately impact upon tumor proliferation, invasion, migration, metastasis, apoptosis, and therapy resistance in cancer cells including hepatocellular carcinoma cells. In recent years, long non-coding RNAs have been reported to be indispensable targets in clinical target therapy to stop the growth of cancer and prolong the lifespan of patients with hepatocellular carcinoma. In this review, we enumerate the signaling pathways and life activities affected by long non-coding RNAs in hepatocellular carcinoma cells to illustrate the role of long non-coding RNAs in the development and therapy resistance of hepatocellular carcinoma.

Long Intergenic Non-Coding RNAs in HNSCC: From "Junk DNA" to Important Prognostic Factor

Head and neck squamous cell carcinoma is one of the most common and fatal cancers worldwide. Even a multimodal approach consisting of standard chemo- and radiotherapy along with surgical resection is only effective in approximately 50% of the cases. The rest of the patients develop a relapse of the disease and acquire resistance to treatment. Especially this group of individuals needs novel, personalized, targeted therapy. The first step to discovering such solutions is to investigate the tumor microenvironment, thus understanding the role and mechanism of the function of coding and non-coding sequences of the human genome. In recent years, RNA molecules gained great interest when the complex character of their impact on our biology allowed them to come out of the shadows of the "junk DNA" label. Furthermore, long non-coding RNAs (lncRNA), specifically the intergenic subgroup (lincRNA), are one of the most aberrantly expressed in several malignancies, which makes them particularly promising future diagnostic biomarkers and therapeutic targets. This review contains characteristics of known and validated lincRNAs in HNSCC, such as XIST, MALAT, HOTAIR, HOTTIP, lincRNA-p21, LINC02487, LINC02195, LINC00668, LINC00519, LINC00511, LINC00460, LINC00312, and LINC00052, with a description of their prognostic abilities. Even though much work remains to be done, lincRNAs are important factors in cancer biology that will become valuable biomarkers of tumor stage, outcome prognosis, and contribution to personalized medicine.

The Landscape of lncRNAs in Hepatocellular Carcinoma: A Translational Perspective

LncRNAs are emerging as relevant regulators of multiple cellular processes involved in cell physiology as well as in the development and progression of human diseases, most notably, cancer. Hepatocellular carcinoma (HCC) is a prominent cause of cancer-related death worldwide due to the high prevalence of causative factors, usual cirrhotic status of the tumor-harboring livers and the suboptimal benefit of locoregional and systemic therapies. Despite huge progress in the molecular characterization of HCC, no oncogenic loop addiction has been identified and most genetic alterations remain non-druggable, underscoring the importance of advancing research in novel approaches for HCC treatment. In this context, long non-coding RNAs (lncRNAs) appear as potentially useful targets as they often exhibit high tumor- and tissue-specific expression and many studies have reported an outstanding dysregulation of lncRNAs in HCC. However, there is a limited perspective of the potential role that deregulated lncRNAs may play in HCC progression and aggressiveness or the mechanisms and therapeutic implications behind such effects. In this review, we offer a clarifying landscape of current efforts to evaluate lncRNA potential as therapeutic targets in HCC using evidence from preclinical models as well as from recent studies on novel oncogenic pathways that show lncRNA-dependency.

The Influence of rs1859168 Polymorphism on Serum Expression of HOTTIP and Its Target miR-615-3p in Egyptian Patients with Breast Cancer

BACKGROUND

Polymorphisms of long noncoding RNAs are lately documented as hazardous factors for the development of numerous tumors. Furthermore, the evaluation of noncoding RNAs has emerged as a novel detector of breast cancer patients. We aimed to genotype the HOXA transcript at the distal tip (HOTTIP) rs1859168 and assess its relationship with the levels of the serum HOTTIP and its target miR-615-3p in patients with breast cancer (BC).

METHODS

One hundred and fifty-one patients with BC, 139 patients with fibroadenoma (FA), and 143 healthy participants were incorporated into the current study. The genotyping of rs1859168 and the measurements of the HOTTIP and miR-615-3p levels were assessed using quantitative real-time PCR.

RESULTS

We revealed a significant association between each of the CC genotypes, C allele, dominant and recessive models, and the increased risk of BC (p = 0.013, p < 0.001, p < 0.001, and p < 0.001, respectively) relative to the healthy controls. Similarly, the CC genotype, C allele, and recessive model were observed to be related to the increased incidence of BC with respect to FA (p < 0.001 for all). A significant upregulation of HOTTIP and a marked decrease of miR-615-3p were verified in patients with BC compared to each of the healthy individuals, patients with FA, and the non-BC group (healthy subjects + FA) (p < 0.001 for all). A significant negative correlation was demonstrated between the expression of HOTTIP and miR-615-3p in the serum of patients with BC. The HOTTIP expression was upregulated, while that of miR-615-3p was downregulated in patients with BC who carried the CC genotype with respect to those who carried the AA or AC genotypes (p < 0.05 for all).

CONCLUSIONS

The genetic variants of rs1859168 are linked to an increased susceptibility to BC. Moreover, HOTTIP and miR-615-3p may be used as novel indicators and targets for the treatment of patients with BC.

LncRNA SNHG6 promotes G1/S-phase transition in hepatocellular carcinoma by impairing miR-204-5p-mediated inhibition of E2F1

Emerging evidence suggests that long noncoding RNAs (lncRNAs) function as competitive endogenous RNA (ceRNA) targeting proteins and genes; however, the role of lncRNAs in hepatocellular carcinoma (HCC) is not well understood. We investigated the mechanism by which lncRNA SNHG6 promotes the development of HCC. RT-qPCR revealed upregulated lncRNA SNHG6 in the HCC setting. Elevated SNHG6 expression was indicative of poor prognosis in patients with HCC. SNHG6 overexpression resulted in increased cyclin D1, cyclin E1, and E2F1 expression both in vitro and in vivo. SNHG6 also promoted HCC cell proliferation by enhancing G1-S phase transition in vitro. Dual luciferase reporter assays, RIP, and RNA pull-down assays demonstrated SNHG6 competitively bound to miR-204-5p and inhibited its expression preventing miR-204-5p from targeting E2F1. Overexpression of miR-204-5p abolished the effect of SNHG6. Our data suggest that SNHG6 functions as a ceRNA that targets miR-204-5p resulting in an increased E2F1 expression and enhanced G1-S phase transition, thereby promoting the tumorigenesis of HCC.

The Impact of Long Non-Coding RNAs in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is among the utmost deadly human malignancies. This type of cancer has been associated with several environmental, viral, and lifestyle risk factors. Among the epigenetic factors which contribute in the pathogenesis of HCC is dysregulation of long non-coding RNAs (lncRNAs). These transcripts modulate expression of several tumor suppressor genes and oncogenes and alter the activity of cancer-related signaling axes. Several lncRNAs such as NEAT1, MALAT1, ANRIL, and SNHG1 have been up-regulated in HCC samples. On the other hand, a number of so-called tumor suppressor lncRNAs namely CASS2 and MEG3 are down-regulated in HCC. The interaction between lncRNAs and miRNAs regulate expression of a number of mRNA coding genes which are involved in the pathogenesis of HCC. H19/miR-15b/CDC42, H19/miR-326/TWIST1, NEAT1/miR-485/STAT3, MALAT1/miR-124-3p/Slug, MALAT1/miR-195/EGFR, MALAT1/miR-22/SNAI1, and ANRIL/miR-144/PBX3 axes are among functional axes in the pathobiology of HCC. Some genetic polymorphisms within non-coding regions of the genome have been associated with risk of HCC in certain populations. In the current paper, we describe the recent finding about the impact of lncRNAs in HCC.

Long non-coding RNA LINC01137 contributes to oral squamous cell carcinoma development and is negatively regulated by miR-22-3p

PURPOSE

Long noncoding RNAs (lncRNAs) are emerging as key regulators in cancer initiation and progression. LINC01137 is a recently identified lncRNA of which the functional role in the development of oral squamous cell carcinoma (OSCC) has not been determined yet.

METHODS

We analyzed the expression of LINC01137 using a microarray-based OSCC gene expression dataset (GSE31056), and validated the results obtained using RT-qPCR in 26 pairs of primary OSCC tumor tissues and adjacent non-tumor tissues. The proliferative and invasive effects of LINC01137 on OSCC cells were determined using CCK-8, colony formation and transwell assays, respectively. Targeted binding between miR-22-3p and LINC01137 was verified using a dual luciferase reporter assay.

RESULTS

We found that LINC01137 was significantly upregulated in primary OSCCs. LINC01137 knockdown inhibited OSCC cell proliferation, migration and invasion, whereas LINC01137 overexpression induced opposite effects. LINC01137 upregulation along with p53 inhibition enhanced the malignant transformation of oral cells. In addition, we found that miR-22-3p can directly target LINC01137 through interaction with a putative miR-22-3p-binding site present within the LINC01137 sequence. A significant negative correlation was observed between LINC01137 and miR-22-3p expression in primary OSCC specimens. Exogenous overexpression of miR-22-3p markedly reduced the endogenous expression level of LINC01137 in OSCC cells. Additional functional assays showed that miR-22-3p overexpression enhanced the inhibitory effect of siRNA-mediated LINC01137 silencing on OSCC cell proliferation, migration and invasion, whereas miR-22-3p inhibition had the opposite effect.

CONCLUSIONS

Our results indicate that LINC01137 functions as an oncogenic lncRNA in OSCC. miR-22-3p can directly target LINC01137 and negatively regulate its expression and function.

Long non-coding RNA PVT1 regulates the migration of hepatocellular carcinoma HepG2 cells via miR-3619-5p/MKL1 axis

Hepatocellular carcinoma (HCC) is the third most common malignant tumor of the digestive system. Plasma cell tumor heterotopic gene 1 (PVT1) is an intergenic long non-coding RNA that is aberrantly expressed in different cancers. Myocardin-related transcription factor A or megakaryoblastic leukemia 1 (MKL1) is a transcriptional coactivator of serum response factor that has been shown to promote cancer cell migration and invasion. In this study, we investigated the relationship between PVT1 and MKL1 as a novel regulatory mechanism underlying HCC progression. We used HepG2 and Cos-7 cell lines. Transfection experiments with miR-3619-5p mimics/inhibitor, PVT1, siRNA-PVT1, MKL1, or siRNA-MKL1 were performed. RNA and protein levels were analyzed by quantitative reverse transcription PCR and Western blot, respectively. Cell migration was assessed by transwell assay. Luciferase assays, RNA-FISH, RNA immunoprecipitation, and chromatin immunoprecipitation assays were performed to confirm the interaction between PVT1, miR-3619-5p, and MKL1 in HCC cells. Overexpression of PVT1 was positively correlated with MKL1 upregulation, which promoted HepG2 cell migration. miR-3619-5p inhibited MKL1 expression in HCC cells by acting on its 3′-UTR. Furthermore, PVT1 promoted MKL1 expression and migration in HCC cells by directly binding to miR-3619-5p. In a positive feedback loop, MKL1 could activate PVT1 transcription by binding to the CArG box in the promoter region. Our findings may provide a basis for the development of novel targeted therapies in HCC.

Hepatitis B Virus DNA Polymerase Restrains Viral Replication Through the CREB1/HOXA Distal Transcript Antisense RNA Homeobox A13 Axis

BACKGROUND AND AIMS

Long noncoding RNAs (lncRNAs) have been associated with infection and hepatitis B virus (HBV)-related diseases, though the underlying mechanisms remain unclear.

APPROACH AND RESULTS

We obtained HBV-HCC lncRNA profiles by deep sequencing and found HOXA distal transcript antisense RNA (HOTTIP) to be significantly up-regulated. RT-qPCR indicated that HOTTIP is highly expressed in HBV-positive hepatoma tissue and induced by HBV in vitro. Virological experiments showed that HOTTIP significantly suppresses the generation of hepatitis B viral surface antigen, hepatitis B viral e antigen and HBV replication. Homeobox A13 (HOXA13), a downstream factor of HOTTIP, was found to bind to HBV enhancer I and X promotor to repress the production of HBV pregenome RNA (pgRNA) and total RNA as well as HBV replication, suggesting that HOXA13 mediates HOTTIP-induced suppression of HBV replication. More interestingly, HBV DNA polymerase (DNA pol) binds to and stabilizes cAMP-responsive element-binding protein 1 (CREB1) mRNA to facilitate translation of the protein, which, in turn, binds to the regulatory element of HOTTIP to promote its expression.

CONCLUSIONS

Our findings demonstrate that HBV DNA pol attenuates HBV replication through activation of the CREB1-HOTTIP-HOXA13 axis. These findings shed light on the mechanism by which HBV restrains replication to contribute to persistent infection.

LncRNA HOTTIP facilitates cell proliferation, invasion, and migration in osteosarcoma by interaction with PTBP1 to promote KHSRP level

This study designs to investigate the role and potential mechanism of lncNRA HOTTIP in OS progression in vitro and in vivo. HOTTIP, PTBP1, and KHSRP expression levels were tested through qRT-PCR and western blot in OS tissues or cell lines. Cell proliferation was examined via CCK-8 and colony formation. Cell cycle and apoptosis were analyzed via flow cytometry analysis. The invasive and migratory abilities of OS cells were evaluated by transwell and wound-healing assays. The localization of HOTTIP in OS cells was determined by subcellular fractionation assay. RNA pull down and RNA immunoprecipitation were allowed to assess the interaction between HOTTIP and PTBP1. Xenograft tumor growth assay was employed to test the role of HOTTIP and KHSRP in OS progression. Our data demonstrated HOTTIP was upregulated in OS tissues. HOTTIP knockdown resulted in a suppression of OS cell proliferation, invasion and migration, as well as a promotion of OS cell apoptosis, while HOTTIP overexpression exhibited opposite effects. In mechanism, PTBP1 and KHSRP highly expressed in OS and HOTTIP was identified to interact with PTBP1 to promote KHSRP expression. Meanwhile, we found that overexpression of KHSRP or PTBP1, individually, can partially remove the repression of HOTTIP suppression for OS cell progression. Moreover, xenograft tumor growth assay revealed that HOTTIP knockdown significantly inhibited tumor growth, and this inhibitory effect was abolished by KHSRP overexpression. Collectively, these findings confirmed that HOTTIP facilitates OS cell proliferation, invasion and migration by binding to PTBP1 to promote KHSRP level. Abbreviation: LncRNA: long noncoding RNA; HOTTIP: HOXA distal transcript antisense RNA; KHSRP: KH-Type Splicing Regulatory Protein; qRT-PCR: quantitative real-time PCR; OS: osteosarcoma; OST: osteosarcoma tissues; ANT: adjacent normal tissue.

Characterizing miRNA-lncRNA Interplay

Long noncoding RNAs (lncRNAs) are noncoding transcripts, usually longer than 200 nt, that constitute one of the largest and significantly heterogeneous RNA families. The annotation of lncRNAs and the characterization of their function is a constantly evolving field. LncRNA interplay with microRNAs (miRNAs) is thoroughly studied in several physiological and disease states. miRNAs are small noncoding RNAs (~22 nt) that posttranscriptionally regulate the expression of protein coding genes, through mRNA target cleavage, degradation or direct translational suppression. miRNAs can affect lncRNA half-life by promoting their degradation, or lncRNAs can act as miRNA "sponges," reducing miRNA regulatory effect on target mRNAs. This chapter outlines the miRNA-lncRNA interplay and provides hands-on methodologies for experimentally supported and in silico-guided analyses. The proposed techniques are a valuable asset to further understand lncRNA functions and can be appropriately adapted to become the backbone for further downstream analyses.

Essential functions of miR-125b in cancer

MicroRNAs (miRNAs) are small and highly conserved non-coding RNAs that silence target mRNAs, and compelling evidence suggests that they play an essential role in the pathogenesis of human diseases, especially cancer. miR-125b, which is the mammalian orthologue of the first discovered miRNA lin-4 in Caenorhabditis elegans, is one of the most important miRNAs that regulate various physiological and pathological processes. The role of miR-125b in many types of cancer has been well established, and so here we review the current knowledge of how miR-125b is deregulated in different types of cancer; its oncogenic and/or tumour-suppressive roles in tumourigenesis and cancer progression; and its regulation with regard to treatment response, all of which are underlined in multiple studies. The emerging information that elucidates the essential functions of miR-125b might help support its potentiality as a diagnostic and prognostic biomarker as well as an effective therapeutic tool against cancer.

Long intergenic noncoding RNA smad7 (Linc-smad7) promotes the epithelial-mesenchymal transition of HCC by targeting the miR-125b/SIRT6 axis

Long intergenic noncoding RNA smad7 (Linc-smad7) has been recently identified as a new long non-coding RNA (lncRNA). However, the role of Linc-smad7 in the tumourigenesis of human cancers remains unknown. This study uncovered that Linc-smad7 was increased in HCC samples and HCC cell lines using RT-qPCR assays. Furthermore, the overexpression of Linc-smad7 indicated poor clinicopathological features and outcomes for HCC patients. In addition, Linc-smad7 promoted HCC cells proliferation, migration, invasion and EMT, as determined by MTT, colony formation, Transwell assays and western blot analysis. Functionally, it was demonstrated that Linc-smad7 could bind with microRNA-125b (miR-125b), and the restoration of miR-125b rescued the promoting effects of Linc-smad7 on HCC cells. Finally, it was observed that sirtuin 6 (SIRT6) was positively regulated by Linc-smad7 in HCC as the direct target of miR-125b, and decreased SIRT6 reversed the effects of Linc-smad7 on promoting HCC. In conclusion, the current study first identified Linc-smad7 is increased in HCC, facilitating HCC cells proliferation, migration, invasion and EMT via regulating the miR-125b/SIRT6 axis.

Hepatocellular carcinoma (HCC): Epidemiology, etiology and molecular classification

Hepatocellular carcinoma (HCC), the primary malignancy of hepatocytes, is a diagnosis with bleak outcome. According to National Cancer Institute's SEER database, the average five-year survival rate of HCC patients in the US is 19.6% but can be as low as 2.5% for advanced, metastatic disease. When diagnosed at early stages, it is treatable with locoregional treatments including surgical resection, Radio-Frequency Ablation, Trans-Arterial Chemoembolization or liver transplantation. However, HCC is usually diagnosed at advanced stages when the tumor is unresectable, making these treatments ineffective. In such instances, systemic therapy with tyrosine kinase inhibitors (TKIs) becomes the only viable option, even though it benefits only 30% of patients, provides only a modest (~3months) increase in overall survival and causes drug resistance within 6months. HCC, like many other cancers, is highly heterogeneous making a one-size fits all option problematic. The selection of liver transplantation, locoregional treatment, TKIs or immune checkpoint inhibitors as a treatment strategy depends on the disease stage and underlying condition(s). Additionally, patients with similar disease phenotype can have different molecular etiology making treatment responses different. Stratification of patients at the molecular level would facilitate development of the most effective treatment option. With the increase in efficiency and affordability of "omics"-level analysis, considerable effort has been expended in classifying HCC at the molecular, metabolic and immunologic levels. This review examines the results of these efforts and the ways they can be leveraged to develop targeted treatment options for HCC.

The emerging roles of non-coding competing endogenous RNA in hepatocellular carcinoma

Accumulating evidence has emerged revealing that noncoding RNAs (ncRNAs) play essential roles in the occurrence and development of hepatocellular carcinoma (HCC). However, the complicated regulatory interactions among various ncRNAs in the development of HCC are not entirely understood. The newly discovered mechanism of competing endogenous RNAs (ceRNAs) uncovered regulatory interactions among different varieties of RNAs. In recent years, a growing number of studies have suggested that ncRNAs, including long ncRNAs, circular RNAs and pseudogenes, play major roles in the biological functions of the ceRNA network in HCC. These ncRNAs can share microRNA response elements to affect microRNA affinity with target RNAs, thus regulating gene expression at the transcriptional level and both physiological and pathological processes. The ncRNAs that function as ceRNAs are involved in diverse biological processes in HCC cells, such as tumor cell proliferation, epithelial-mesenchymal transition, invasion, metastasis and chemoresistance. Based on these findings, ncRNAs that act as ceRNAs may be promising candidates for clinical diagnosis and treatments. In this review, we discuss the mechanisms and research methods of ceRNA networks. We also reviewed the recent advances in studying the roles of ncRNAs as ceRNAs in HCC and highlight possible directions and possibilities of ceRNAs as diagnostic biomarkers or therapeutic targets. Finally, the limitations, gaps in knowledge and opportunities for future research are also discussed.

LncRNA DDX11-AS1: a novel oncogene in human cancer

Long noncoding RNA (lncRNA) is a newly identified type of noncoding RNA with a length of more than 200 nucleotides. The latest research shows that lncRNAs play important roles in the occurrence and development of human tumours by acting both as carcinogenic genes and as tumour suppressor genes. LncRNAs plays a role in various biological processes, such as cell growth, apoptosis, migration and invasion. The newly discovered lncRNA DDX11-AS1 is abnormally highly expressed in various malignant tumours, such as hepatocellular carcinoma, colorectal cancer, osteosarcoma, bladder cancer, NSCLC and gastric cancer. DDX11-AS1 mainly regulates the expression of related genes through direct or indirect ways to perform its functions in carcinogenicity. These results indicate that DDX11-AS1 may be a marker or therapeutic target of tumours. This review summarizes the biological function and mechanism of DDX11-AS1 in the process of tumour development.

MiR-509-3-5p-NONHSAT112228.2 Axis Regulates p21 and Suppresses Proliferation and Migration of Lung Cancer Cells

Background:

Although the involvement of individual microRNA and lncRNA in the regulation of p21 expression has largely been evidenced, less is known about the roles of functional interactions between miRNAs and lncRNAs in p21 expression. Our previous work demonstrated that miR-509- 3-5p could block cancer cell growth.

Methods:

To gain an insight into the role of miR-509-3-5p in the regulation of p21 expression, we performed in silico prediction and showed that miR-509-3-5p might target the NONHSAT112228.2, a sense-overlapping lncRNA transcribed by a non-code gene overlapping with p21 gene. Mutation and luciferase report analysis suggested that miR-509-3-5p could target NONHSAT112228.2, thereby blocking its expression. Consistently, NONHSAT112228.2 expression was inversely correlated with both miR-509-3-5p and p21 expression in cancer cells. Ectopic expression of miR-509-3-5p and knockdown of NONHSAT112228.2 both promoted proliferation and migration of cancer cells.

Results:

Interestingly, high-expression of NONHSAT112228.2 accompanied by low-expression of p21 was observed in lung cancer tissues and associated with lower overall survival.

Conclusion:

Taken together, our study found a new regulatory pathway of p21, in which MiR-509-3-5p functionally interacts with NONHSAT112228.2 to release p21 expression. MiR-509-3-5p— NONHSAT112228.2 regulatory axis can inhibit the proliferation and migration of lung cancer cells.

LncRNAs in HCV Infection and HCV-Related Liver Disease

Long non-coding RNAs (lncRNAs) are transcripts with poor coding capacity that may interact with proteins, DNA, or other RNAs to perform structural and regulatory functions. The lncRNA transcriptome changes significantly in most diseases, including cancer and viral infections. In this review, we summarize the functional implications of lncRNA-deregulation after infection with hepatitis C virus (HCV). HCV leads to chronic infection in many patients that may progress to liver cirrhosis and hepatocellular carcinoma (HCC). Most lncRNAs deregulated in infected cells that have been described function to potentiate or block the antiviral response and, therefore, they have a great impact on HCV viral replication. In addition, several lncRNAs upregulated by the infection contribute to viral release. Finally, many lncRNAs have been described as deregulated in HCV-related HCC that function to enhance cell survival, proliferation, and tumor progression by different mechanisms. Interestingly, some HCV-related HCC lncRNAs can be detected in bodily fluids, and there is great hope that they could be used as biomarkers to predict cancer initiation, progression, tumor burden, response to treatment, resistance to therapy, or tumor recurrence. Finally, there is high confidence that lncRNAs could also be used to improve the suboptimal long-term outcomes of current HCC treatment options.

Serum miRNAs, a potential prognosis marker of loco-regionally advanced nasopharyngeal carcinoma patients treated with CCRT

Background

Serum miRNA was once found as potential disease survival index,thus we investigated the role of miRNA in predicting prognosis in loco-regionally advanced NPC patients treated with CCRT.

Methods

This study included two phases: (i) We enrolled 3 NPC patients with recurrence or distant metastasis (experimental group, EG) and 3 NPC patients in clinical remission (control group, CG),who were treated with CCRT within 5 years. The paired serum was collected before and after treatment and biomarkers were discovered by LNA-TaqMan Human MicroRNA Arrays. (ii) we used the bioinformatic analysis, marker selection and an independent validation by qRT-PCR to analyse the serums of 29 NPC patients with recurrent disease or distant metastasis and 19 NPC patients in clinical remission treated with CCRT. Using the Kaplan-Meier method, log-rank test and Cox regression model to estimate the accuracy of the miRNAs to predict PFS and OS, and identified factors significantly associated with prognosis, respectively.

Results

Using fold change≥2.0 or ≤ 0.5 and p ≤ 0.05 as cutoff levels, we identified 1 up-regulated and 6 down-regulated miRNAs, 1 up-regulated and 9 down-regulated miRNAs in EG versus CG before and after CCRT, respectively. After these down-regulated miRNAs were dealed with bioinformatics analysis and normalization, only 5 different miRNAs were significantly reduced, which there were no significant difference in the expression of miRNA-26b, miRNA-29a and miRNA-125b before CCRT, and the expression of miRNA-143 and miRNA-29b after CCRT in the serum samples of 48 NPC patients. Based on this, we calculated a risk score with the expression of miRNA-26b、miRNA-29a、miRNA-125b、miRNA-29b、miRNA-143 and then classified patients as high or low risk group. Cox regression model suggested that combining miRNA-29a and miRNA-125b before CCRT with miRNA-26b after CCRT was independent prognostic factors for PFS (HR = 3.149, 95%CI:1.018–9.115, p = 0.034), whereas combining the former two is independent for OS (HR = 5.146, 95%CI:1.674–15.817, p = 0.04).

Conclusions

For loco-regionally advanced NPC patients treated with CCRT, especially high-risk patients- serum miRNAs, such as miRNA-29a, miRNA-125b and miRNA-26b etc., play an important role in predicting prognosis factors of PFS and OS, which will contribute to the strategic direction for future research.

The Roles and Mechanisms of lncRNAs in Liver Fibrosis

Many studies have revealed that circulating long noncoding RNAs (lncRNAs) regulate gene and protein expression in the process of hepatic fibrosis. Liver fibrosis is a reversible wound healing response followed by excessive extracellular matrix accumulation. In the development of liver fibrosis, some lncRNAs regulate diverse cellular processes by acting as competing endogenous RNAs (ceRNAs) and binding proteins. Previous investigations demonstrated that overexpression of lncRNAs such as H19, maternally expressed gene 3 (MEG3), growth arrest-specific transcript 5 (GAS5), Gm5091, NR_002155.1, and HIF 1alpha-antisense RNA 1 (HIF1A-AS1) can inhibit the progression of liver fibrosis. Furthermore, the upregulation of several lncRNAs [e.g., nuclear paraspeckle assembly transcript 1 (NEAT1), hox transcript antisense RNA (Hotair), and liver-enriched fibrosis-associated lncRNA1 (lnc-LFAR1)] has been reported to promote liver fibrosis. This review will focus on the functions and mechanisms of lncRNAs, the lncRNA transcriptome profile of liver fibrosis, and the main lncRNAs involved in the signalling pathways that regulate hepatic fibrosis. This review provides insight into the screening of therapeutic and diagnostic markers of liver fibrosis.

Long non-coding RNA HOTAIR and HOTTIP as potential biomarkers for hepatitis C virus genotype 4-induced hepatocellular carcinoma

Background

Long non-coding RNAs (lncRNAs) homeobox (Hox) transcript antisense intergenic RNA (HOTAIR) and HOXA transcript at the distal tip (HOTTIP) have been suggested to be implicated in liver cancer tumorigenesis and progression; however, little is known about the role of the plasma HOTAIR and HOTTIP in liver cancer diagnosis and prognosis. The current study aimed at measuring the plasma levels of long non-coding RNAs (HOTAIR and HOTTIP) expression in chronic liver disease (CLD) due to HCV genotype 4 infection with/without cirrhosis and HCC patients in an attempt to evaluate the potential benefits of these new circulating as non-invasive diagnostic biomarkers and a novel therapeutic strategy for liver cirrhosis and carcinogenesis of Egyptian patients. Hundred subjects were included in this study, divided into two groups; group I (50 patients) were classified into subgroup Ia (CLD without cirrhosis, n = 25) and subgroup Ib (CLD with cirrhosis, n = 25), group II (CLD patients with HCC, n = 25), and control (healthy volunteer, n = 25). The expression of lncRNAs (HOTAIR and HOTTIP) genes was analyzed by real-time PCR.

Results

LncRNAs (HOTAIR and HOTTIP) showed upregulation in all diseased groups, which was in consistent with the progression of the disease toward the HCC stage. In addition, HOTAIR and HOTTIP showed a diagnostic ability to discriminate between cases of cirrhosis and HCC compared with healthy control (p < 0.001), while HOTAIR and HOTTIP did not show a discrimination significant differences between cirrhotic cases and non-cirrhotic cases. By using receiver operating characteristic curve (ROC) analysis, it was found that LncRNAs (HOTAIR and HOTTIP) could diagnose liver cancer with 64.0% sensitivity and 86.0% specificity and 48.0% sensitivity and 88.0% specificity. Furthermore, both genes can be considered as the predictor and prognostic parameters for cirrhosis (OR = 1.111, p = 0.05) and (OR = 1.07, p = 0.05) respectively, and HCC (OR = 1.047, p = 0.01) and (OR = 1.05, p = 0.003). The increased HOTAIR and HOTTIP expression were associated with advanced tumor stages and higher grades.

Conclusion

These results strongly prompt us that HOTAIR and HOTTIP genes can be used as non-invasive prognostic biomarkers and new therapeutic targets for HCV genotype 4-induced HCC.

Long noncoding RNA linc00467 plays an oncogenic role in hepatocellular carcinoma by regulating the miR-18a-5p/NEDD9 axis

Increasing evidence has shown that numerous long noncoding RNAs (lncRNAs) play critical roles in tumorigenesis. Herein, we investigated the biological role of lncRNA linc00467 in the cancer biology of hepatocellular carcinoma (HCC). We observed that linc00467 was upregulated in HCC tissues and cells. Silencing of linc00467 using small interfering RNA interference significantly inhibited the growth and motility of HCC cells, and increased cell apoptosis through regulating the Bcl-2/Bax axis and the caspase cascade, suggesting that linc00467 exerted oncogenic functions in the progression of HCC. Moreover, we found that linc00467 could target miR-18a-5p, and NEDD9 was a target for miR-18a-5p in HCC cells. Furthermore, either the miR-18a-5p inhibitor or upregulation of NEDD9 could recover the inhibitory effects caused by silencing of linc00467. In conclusion, our data highlighted the oncogenic role of linc00467 in HCC progression by regulating the miR-18a-5p/NEDD9 axis.

Exosome-Mediated Transfer of lncRNA HOTTIP Promotes Cisplatin Resistance in Gastric Cancer Cells by Regulating HMGA1/miR-218 Axis

Background

Chemoresistance has become a major obstacle for cancer therapy in clinic. Long noncoding RNAs (lncRNAs) have been reported to play critical roles in the development of chemoresistance in various tumors, including gastric cancer (GC). However, the role of HOXA transcript at the distal tip (HOTTIP) within extracellular vesicles (exosomes) in cisplatin-resistant GC cells remains largely unknown.

Materials and methods

Cell proliferation, migration and invasion were detected using Cell Counting Kit-8 (CCK-8) and transwell assays, respectively. Western blot assay was employed to analyze the protein levels of E-cadherin, N-cadherin, Vimentin, CD63, CD83, GRP78, HMGA1, and high-mobility group A1 (HMGA1). The expression levels of HOTTIP, microRNA-218 (miR-218) and HMGA1were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The interaction between miR-218 and HOTTIP or HMGA1 was predicted by bioinformatics software and confirmed by the dual-luciferase reporter and RNA immunoprecipitation (RIP) assays.

Results

Cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) were promoted in cisplatin-resistant GC cells. HOTTIP level was upregulated in cisplatin-resistant GC cells and its downregulation enhanced cisplatin sensitivity. Moreover, extracellular HOTTIP could be incorporated into exosomes and transmitted to sensitive cells, thus disseminating cisplatin resistance. Additionally, exosomal HOTTIP promoted cisplatin resistance via activating HMGA1 in GC cells. Interestingly, HMGA1 was a target of miR-218 and miR-218 could directly bind to HOTTIP. Clinically, high expression of exosomal HOTTIP in serum was associated with poor response to cisplatin treatment in GC patients.

Conclusion

Exosomal HOTTIP contributed to cisplatin resistance in GC cells by regulating miR-218/HMGA1 axis, providing a novel avenue for the treatment of GC.

The Long Non-coding RNA HOTTIP Is Highly Expressed in Colorectal Cancer and Enhances Cell Proliferation and Invasion

Long non-coding RNAs (lncRNAs) are associated with a spectrum of biological processes such as gene regulation on transcriptional and post-transcriptional levels. The HOXA transcript at the distal tip (HOTTIP) lncRNA plays an important role in carcinogenesis; however, the underlying role of HOTTIP in colorectal carcinoma (CRC) remains unknown. The aim of the present study was to evaluate the expression and function of HOTTIP in CRC. In the present study, we analyzed HOTTIP expression levels of CRC patients in tumor and adjacent normal tissue by real-time quantitative PCR. Knockdown of HOTTIP by RNA interference was performed to explore its roles in cell proliferation, migration, and invasion. Our results found that HOTTIP was upregulated in human primary CRC tissues. Knockdown of HOTTIP inhibited CRC cell proliferation, migration, and invasion. Above all, knockdown of HOTTIP could represent a rational therapeutic strategy for CRC.

Long non‑coding RNAs in HBV‑related hepatocellular carcinoma (Review)

Hepatitis B virus (HBV)‑related hepatocellular carcinoma (HCC) is a global health problem that accounts for more than half of total liver cancer cases in developing countries. Despite the growing number of researches conducted, the molecular mechanism underlying the development of HCC remains elusive. Long non‑coding RNAs (lncRNAs), which are non‑coding RNAs >200 nt in length that were previously considered to be transcriptional noise, have been found to be dysregulated in HBV‑related HCC with the help of high‑throughput omics techniques. Subsequent investigations revealed that aberrant expression of lncRNAs may affect the risk of HBV‑related HCC through diverse mechanisms, including epigenetic silencing of transcriptional activation, alternative splicing, molecular sponging, modulating protein stability, and by serving as precursors of miRNAs. Although the sensitivity and specificity of lncRNAs must be further validated, a number of circulating lncRNAs have been identified as useful biomarkers for HBV‑related HCC. In addition to these findings, recent studies also unveiled that certain genetic polymorphisms in lncRNAs may affect the occurrence and prognosis of HBV‑related HCC. The aim of the present review was to provide an overview of the mechanisms underlying the involvement of lncRNAs in HBV‑related HCC. Subsequently, lncRNAs found to be dysregulated in HBV‑related HCC were focused on and current findings on circulating lncRNAs and their genetic polymorphisms were discussed.