Long non-coding RNAs and hepatocellular carcinoma

Unlocking the Secrets of Extracellular Vesicles: Orchestrating Tumor Microenvironment Dynamics in Metastasis, Drug Resistance, and Immune Evasion

Extracellular vehicles (EVs) are gaining increasing recognition as central contributors to the intricate landscape of the tumor microenvironment (TME). This manuscript provides an extensive examination of the multifaceted roles played by EVs in shaping the TME, with a particular emphasis on their involvement in metastasis, drug resistance, and immune evasion. Metastasis, the process by which cancer cells disseminate to distant sites, remains a formidable challenge in cancer management. EVs, encompassing exosomes and microvesicles, have emerged as critical participants in this cascade of events. They facilitate the epithelial-to-mesenchymal transition (EMT), foster pre-metastatic niche establishment, and enhance the invasive potential of cancer cells. This manuscript delves into the intricate molecular mechanisms underpinning these processes, underscoring the therapeutic potential of targeting EVs to impede metastasis. Drug resistance represents a persistent impediment to successful cancer treatment. EVs are instrumental in intrinsic and acquired drug resistance, acting as mediators of intercellular communication. They ferry molecules like miRNAs and proteins, which confer resistance to conventional chemotherapy and targeted therapies. This manuscript scrutinizes the diverse strategies employed by EVs in propagating drug resistance while also considering innovative approaches involving EV-based drug delivery systems to counteract this phenomenon. Immune evasion is a hallmark of cancer, and EVs are central in sculpting the immunosuppressive milieu of the TME. Tumor-derived EVs thwart immune responses through various mechanisms, including T cell dysfunction induction, the expansion of regulatory T cells (Tregs), and polarization of macrophages towards an immunosuppressive phenotype. In addition, the manuscript explores the diagnostic potential of EVs as biomarkers and their role as therapeutic agents in immune checkpoint blockade therapies. This manuscript provides a comprehensive overview of EV's pivotal role in mediating intricate interactions within the TME, ultimately influencing cancer progression and therapeutic outcomes. A profound understanding of EV-mediated processes in metastasis, drug resistance, and immune evasion opens up promising avenues for developing innovative therapeutic strategies and identifying valuable biomarkers in the ongoing battle against cancer.

The Expression Patterns and Implications of MALAT1, MANCR, PSMA3-AS1 and miR-101 in Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) is a malignant tumor with poorly understood molecular mechanisms. This study endeavors to elucidate how the long non-coding RNAs (lncRNAs) MALAT1, MANCR and PSMA3-AS1, as well as the microRNA miR-101, exhibit specific expression patterns in the pathogenesis and prognosis of EAC. A total of 50 EAC tissue samples (tumors and lymph nodes) and a control group comprising 26 healthy individuals were recruited. The samples underwent quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses. The relative expression levels of MALAT1, MANCR, PSMA3-AS1, and miR-101 were ascertained and correlated with various clinicopathological parameters including TNM staging, tumor characteristics (size and grade of the tumor) lymphatic invasion, disease-free (DFS) and overall survival (OS) of EAC patients. Quantitative analyses revealed that MALAT1 and MANCR were significantly upregulated in EAC tumors and positive lymph nodes when compared to control tissues (p < 0.05). Such dysregulations correlated positively with advanced lymphatic metastases and a higher N stage. DFS in the subgroup of patients with negative lymph nodes was higher in the setting of low-MANCR-expression patients compared to patients with high MANCR expression (p = 0.02). Conversely, miR-101 displayed a significant downregulation in EAC tumors and positive lymph nodes (p < 0.05), and correlated negatively with advanced tumor stage, lymphatic invasion and the grade of the tumor (p = 0.006). Also, patients with low miR-101 expression showed a tendency towards inferior overall survival. PSMA3-AS1 did not demonstrate statistically significant alterations (p > 0.05). This study reveals MALAT1, MANCR, and miR-101 as putative molecular markers for prognostic evaluation in EAC and suggests their involvement in EAC progression.

Roles of non-coding RNAs in cell death pathways involved in the treatment of resistance and recurrence of cancer

Considering the burden of cancer, a number of methods have been applied to control or stop it. However, because of drug resistance or cancer recurrence, these treatments usually face failure. Combination of modulation of expression of non-coding RNAs (ncRNAs) with other treatments can increase treatment-sensitivity of tumors but these approaches still face some challenges. Gathering information in this field is a prerequisite to find more efficient cures for cancer. Cancer cells use ncRNAs to enhance uncontrolled proliferation originated from inactivation of cell death routs. In this review article, the main routes of cell death and involved ncRNAs in these routes are discussed. Moreover, extant information in the role of different ncRNAs on cell death pathways involved in the treatment resistance and cancer recurrence is summarized.

Long Noncoding RNA H19: A Novel Oncogene in Liver Cancer

Liver cancer is the second leading cause of cancer-related death globally, with limited treatment options. Recent studies have demonstrated the critical role of long noncoding RNAs (lncRNAs) in the pathogenesis of liver cancers. Of note, mounting evidence has shown that lncRNA H19, an endogenous noncoding single-stranded RNA, functions as an oncogene in the development and progression of liver cancer, including hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), the two most prevalent primary liver tumors in adults. H19 can affect many critical biological processes, including the cell proliferation, apoptosis, invasion, and metastasis of liver cancer by its function on epigenetic modification, H19/miR-675 axis, miRNAs sponge, drug resistance, and its regulation of downstream pathways. In this review, we will focus on the most relevant molecular mechanisms of action and regulation of H19 in the development and pathophysiology of HCC and CCA. This review aims to provide valuable perspectives and translational applications of H19 as a potential diagnostic marker and therapeutic target for liver cancer disease.

Function of the Long Noncoding RNAs in Hepatocellular Carcinoma: Classification, Molecular Mechanisms, and Significant Therapeutic Potentials

Hepatocellular carcinoma (HCC) is the most common and serious type of primary liver cancer. HCC patients have a high death rate and poor prognosis due to the lack of clear signs and inadequate treatment interventions. However, the molecular pathways that underpin HCC pathogenesis remain unclear. Long non-coding RNAs (lncRNAs), a new type of RNAs, have been found to play important roles in HCC. LncRNAs have the ability to influence gene expression and protein activity. Dysregulation of lncRNAs has been linked to a growing number of liver disorders, including HCC. As a result, improved understanding of lncRNAs could lead to new insights into HCC etiology, as well as new approaches for the early detection and treatment of HCC. The latest results with respect to the role of lncRNAs in controlling multiple pathways of HCC were summarized in this study. The processes by which lncRNAs influence HCC advancement by interacting with chromatin, RNAs, and proteins at the epigenetic, transcriptional, and post-transcriptional levels were examined. This critical review also highlights recent breakthroughs in lncRNA signaling pathways in HCC progression, shedding light on the potential applications of lncRNAs for HCC diagnosis and therapy.

The Role of Extracellular Vesicles as Shuttles of RNA and Their Clinical Significance as Biomarkers in Hepatocellular Carcinoma

Extracellular vesicles (EVs) have attracted interest as mediators of intercellular communication following the discovery that EVs contain RNA molecules, including non-coding RNA (ncRNA). Growing evidence for the enrichment of peculiar RNA species in specific EV subtypes has been demonstrated. ncRNAs, transferred from donor cells to recipient cells, confer to EVs the feature to regulate the expression of genes involved in differentiation, proliferation, apoptosis, and other biological processes. These multiple actions require accuracy in the isolation of RNA content from EVs and the methodologies used play a relevant role. In liver, EVs play a crucial role in regulating cell-cell communications and several pathophysiological events in the heterogeneous liver class of cells via horizontal transfer of their cargo. This review aims to discuss the rising role of EVs and their ncRNAs content in regulating specific aspects of hepatocellular carcinoma development, including tumorigenesis, angiogenesis, and tumor metastasis. We analyze the progress in EV-ncRNAs' potential clinical applications as important diagnostic and prognostic biomarkers for liver conditions.

PHAROH lncRNA regulates Myc translation in hepatocellular carcinoma via sequestering TIAR

Hepatocellular carcinoma, the most common type of liver malignancy, is one of the most lethal forms of cancer. We identified a long non-coding RNA, Gm19705, that is overexpressed in hepatocellular carcinoma and mouse embryonic stem cells. We named this RNA Pluripotency and Hepatocyte Associated RNA Overexpressed in HCC, or PHAROH. Depletion of PHAROH impacts cell proliferation and migration, which can be rescued by ectopic expression of PHAROH. RNA-seq analysis of PHAROH knockouts revealed that a large number of genes with decreased expression contain a Myc motif in their promoter. MYC is decreased in knockout cells at the protein level, but not the mRNA level. RNA-antisense pulldown identified nucleolysin TIAR, a translational repressor, to bind to a 71-nt hairpin within PHAROH, sequestration of which increases MYC translation. In summary, our data suggest that PHAROH regulates MYC translation by sequestering TIAR and as such represents a potentially exciting diagnostic or therapeutic target in hepatocellular carcinoma.

LncRNA TTN-AS1 intensifies sorafenib resistance in hepatocellular carcinoma by sponging miR-16-5p and upregulation of cyclin E1

Drug resistance has always been an important problem affecting the therapeutic effect of hepatocellular carcinoma (HCC). To investigate the potential role of lncRNA TTN-AS1 in HCC cells with sorafenib (SOR) resistance, and explore the underlying pathways, quantitative real time polymerase chain reaction (qRT-PCR) was used to test the expression of TTN-AS1 in HCC tissues and cells. Then, the expression of TTN-AS1 was down-regulated by shRNA, the activity changes, apoptosis and related protein expression in HCC cells with/without SOR treatment were observed in succession. Expression levels of the downstream target of TTN-AS1, miR-16-5p were studied by dual-luciferase binding assay, cell proliferation, and western blotting analysis. Nude mice models of human HCC with TTN-AS1 gene knockdown were established to observe the tumor growth. As the results revealed, TTN-AS1 silencing in HCC cells induced apoptosis by enhancing the sensitivity of cells to SOR, and the tumor in nude mice became smaller. The mechanism study showed that miR-16-5p was affected by TTN-AS1 sponge, up-regulated cyclin E1 expression, and regulated PTEN/Akt signaling pathway, thereby significantly alleviating the inhibition of apoptosis of HCC cells induced by TTN-AS1 gene. Collectively, our results provided TTN-AS1 as a potential therapeutic target for sorafenib resistance in HCC.

Role of extracellular vesicles in tumour microenvironment

In recent years, it has been demonstrated that extracellular vesicles (EVs) can be released by almost all cell types, and detected in most body fluids. In the tumour microenvironment (TME), EVs serve as a transport medium for lipids, proteins, and nucleic acids. EVs participate in various steps involved in the development and progression of malignant tumours by initiating or suppressing various signalling pathways in recipient cells. Although tumour-derived EVs (T-EVs) are known for orchestrating tumour progression via systemic pathways, EVs from non-malignant cells (nmEVs) also contribute substantially to malignant tumour development. Tumour cells and non-malignant cells typically communicate with each other, both determining the progress of the disease. In this review, we summarise the features of both T-EVs and nmEVs, tumour progression, metastasis, and EV-mediated chemoresistance in the TME. The physiological and pathological effects involved include but are not limited to angiogenesis, epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) remodelling, and immune escape. We discuss potential future directions of the clinical application of EVs, including diagnosis (as non-invasive biomarkers via liquid biopsy) and therapeutic treatment. This may include disrupting EV biogenesis and function, thus utilising the features of EVs to repurpose them as a therapeutic tool in immunotherapy and drug delivery systems. We also discuss the overall findings of current studies, identify some outstanding issues requiring resolution, and propose some potential directions for future research. Video abstract.

Bioinformatics analyses and biological function of lncRNA ZFPM2-AS1 and ZFPM2 gene in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most lethal malignant tumors worldwide; however, the etiology of HCC still remains poorly understood. In the present study, cancer-omics databases, including The Cancer Genome Atlas, GTEx and Gene Expression Omnibus, were systematically analyzed in order to investigate the role of the long non-coding RNA (lncRNA) zinc finger protein, FOG family member 2-antisense 1 (ZFPM2-AS1) and the zinc finger protein, FOG family member 2 (ZFPM2) gene in the occurrence and progression of HCC. It was identified that the expression levels of lncRNA ZFPM2-AS1 were significantly increased in HCC tissues, whereas expression levels of the ZFPM2 gene were significantly decreased in HCC tissues compared with normal liver tissues. Higher expression levels of ZFPM2-AS1 were significantly associated with a less favorable prognosis of HCC, whereas higher expression levels of the ZFPM2 gene were associated with a more favorable prognosis of HCC. Genetic alterations in the ZFPM2 gene may contribute to a worse prognosis of HCC. Validation of the GSE14520 dataset also demon stared that ZFPM2 gene expression levels were significantly decreased in HCC tissues (P<0.001). The receiver operating characteristic (ROC) analysis of the ZFPM2 gene indicated high accuracy of this gene in distinguishing between HCC tissues and non-tumor tissues. The areas under the ROC curves were >0.8. Using integrated strategies, the present study demonstrated that lncRNA ZFPM2-AS1 and the ZFPM2 gene may contribute to the occurrence and prognosis of HCC. These findings may provide a novel understanding of the molecular mechanisms underlying the occurrence and prognosis of HCC.

Roles and Regulation of Long Noncoding RNAs in Hepatocellular Carcinoma

Next-generation sequencing has uncovered thousands of long noncoding RNAs (lncRNA). Many are reported to be aberrantly expressed in various cancers, including hepatocellular carcinoma (HCC), and play key roles in tumorigenesis. This review provides an in-depth discussion of the oncogenic mechanisms reported to be associated with deregulated HCC-associated lncRNAs. Transcriptional expression of lncRNAs in HCC is modulated through transcription factors, or epigenetically by aberrant histone acetylation or DNA methylation, and posttranscriptionally by lncRNA transcript stability modulated by miRNAs and RNA-binding proteins. Seventy-four deregulated lncRNAs have been identified in HCC, of which, 52 are upregulated. This review maps the oncogenic roles of these deregulated lncRNAs by integrating diverse datasets including clinicopathologic features, affected cancer phenotypes, associated miRNA and/or protein-interacting partners as well as modulated gene/protein expression. Notably, 63 deregulated lncRNAs are significantly associated with clinicopathologic features of HCC. Twenty-three deregulated lncRNAs associated with both tumor and metastatic clinical features were also tumorigenic and prometastatic in experimental models of HCC, and eight of these mapped to known cancer pathways. Fifty-two upregulated lncRNAs exhibit oncogenic properties and are associated with prominent hallmarks of cancer, whereas 22 downregulated lncRNAs have tumor-suppressive properties. Aberrantly expressed lncRNAs in HCC exert pleiotropic effects on miRNAs, mRNAs, and proteins. They affect multiple cancer phenotypes by altering miRNA and mRNA expression and stability, as well as through effects on protein expression, degradation, structure, or interactions with transcriptional regulators. Hence, these insights reveal novel lncRNAs as potential biomarkers and may enable the design of precision therapy for HCC.

Current Research Progress on Long Noncoding RNAs Associated with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of mortality among cancers. It has been found that long noncoding RNAs (lncRNAs) are involved in many human cancers, including liver cancer. It has been identified that carcinogenic and tumor-suppressing lncRNAs are associated with complex processes in liver cancer. These lncRNAs may participate in a variety of pathological and biological activities, such as cell proliferation, apoptosis, invasion, and metastasis. Here, we review the regulation and function of lncRNA in liver cancer and evaluate the potential of lncRNA as a new goal for liver cancer.

LINC00339 promotes growth and invasiveness of hepatocellular carcinoma by the miR-1182/SKA1 pathway

Background: Extensive research has shown that long noncoding RNA (lncRNA) is involved in tumorigenesis, including hepatocellular carcinoma (HCC). The lncRNA LINC00339 was reported to regulate the development of lung cancer or breast cancer. However, whether LINC00339 participates in HCC progression remains unclear. Here, our results showed that LINC00339 was upregulated in HCC.

Methods: qRT-PCR and in situ hybridization (ISH) was used to analyze LINC00339 expression in tumor tissues and cell lines. CCK8 and colony formation assays were used to analyze cell proliferation. Transwell assay was used to analyze cell migration and invasion. Xenograft experiment was used to test tumor growth in vivo.

Results: LINC00339 overexpression was correlated with an advanced stage, metastasis, and bad prognosis in HCC patients. Functional investigation showed that LINC00339 knockdown significantly suppressed HCC cell proliferation, migration, and invasion. Moreover, decreased LINC00339 expression inhibited HCC growth in vivo. Mechanistically, LINC00339 could interact with miR-1182 to promote SKA1 expression. We also demonstrated that SKA1 acted as an oncogene and SKA1 upregulation reversed the effect of LINC00339 silencing.

Conclusion: Our results illustrated that the LINC00339/miR-1182/SKA1 axis plays an essential role in HCC progression.

Down-regulation expression of TGFB2-AS1 inhibits the proliferation, migration, invasion and induces apoptosis in HepG2 cells

BACKGROUND

Hepatocellular carcinoma (HCC) is the leading cause of cancer mortality and without effective prognosis. Previous study has been confirmed that the abnormal expression of long non-coding RNAs (lncRNAs) TGFB2-AS1 was involved in tumorigenesis. However, the biological functions of TGFB2-AS1 in hepatocellular carcinoma (HCC) remain largely unclear.

OBJECTIVE

We comprehensively assess the clinical significance of TGFB2-AS1 and investigate the biological functions of TGFB2-AS1 on HCC HepG2 cells.

METHODS

We firstly confirmed the expression of TGFB2-AS1 between tumor and normal tissues using public available transcriptome data. We analyzed the clinical significance of TGFB2-AS1 using the TCGA HCC datasets. The biological functions of TGFB2-AS1 on HCC HepG2 cells were explored by multiple in vitro assays.

RESULTS

We found that TGFB2-AS1 was remarkably increased in HCC tissues (P = 0.00148) and exhibited a potential predictive marker for HCC, with an area under curve (AUC) of 0.708 (P = 0.0034) using the fifty pairs of matched HCC tissues of TCGA. Besides, higher expression of TGFB2-AS1 in HCC tissues was identified as being positively associated with advanced tumor (P = 0.012) and disease stage (P = 0.009) in 355 HCC cases using independent sample nonparametric test. Downregulation of TGFB2-AS1 expression significantly restrained proliferation (P < 0.01) and impaired colony formation (P < 0.05). Furthermore, TGFB2-AS1 depletion remarkably promoted the apoptosis of HepG2 cells (P < 0.05) and inhibited migration and invasion (P < 0.01).

CONCLUSION

Taken together, these findings suggested that TGFB2-AS1 might serve as a potential therapeutic target for HCC.

The anti-tumor activity of brown seaweed oligo-fucoidan via lncRNA expression modulation in HepG2 cells

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death in Asia. HCC is less sensitive to chemotherapy and is known to express multidrug resistant genes to acquire resistance to chemotherapeutic agents, therefore the development of a potent HCC suppressor is essential in treating HCC. Our previous reports demonstrated that oligo-fucoidan from the brown seaweed Sargassum hemiphyllum elevates microRNA-29b to inhibit epithelial-mesenchymal transition in hepatoma cells. In this study, we aimed to examine in vitro effect of oligo-fucoidan in hepatocellular carcinoma through apoptosis and long noncoding RNA (lncRNA) pathway. Oligo-fucoidan was studied for its anti-hepatoma cells by MTT and DNA ladder analysis. And the mechanism was studied by flow cytometry, qPCR and western blot analysis. In this study, oligo-fucoidan induced sub-G1 phase cell cycle arrest and activation of caspases, indicating that the intrinsic and extrinsic apoptotic pathways were involved in the mechanism of oligo-fucoidan-induced cell death. Moreover, oligo-fucoidan significantly increased the expression of p53, p21, and p27, while cyclin-B1 and -D1 were decreased at the mRNA and protein levels. Finally, we showed that targeting apoptosis and cell cycle pathways could also contribute to the induction of the lncRNA-Saf and lncRNA-p21. Through human lncRNA profiler array analysis, the differential expression of lncRNAs in HCC cells following oligo-fucoidan exposure was further examined. These findings indicated that lncRNAs switched oligo-fucoidan-induced apoptosis, which might be potentially valuable in HCC adjuvant therapy.

LncRNA-H19 activates CDC42/PAK1 pathway to promote cell proliferation, migration and invasion by targeting miR-15b in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the main causes of cancer-related death. This study aims to explore the role and underlying mechanism of H19 in HCC.

METHODS

qRT-PCR detected miR-15b-5p and H19 expression, as well as the mRNA level of EMT-associated genes. Western blotting detected protein level of EMT-associated genes. Immunohistochemistry (IHC) examined CDC42 in HCC tissues. Dual luciferase reporter assay verified the regulatory mechanism among H19, miR-15b and CDC42. Colony formation, wound healing assay, transwell, flow cytometry measured proliferation, migration, invasion and apoptosis, respectively.

RESULTS

H19 and CDC42 were up-regulated while miR-15b was down-regulated in HCC cells and tissues. miR-15b interacted with H19 and CDC42 3'-UTR. H19 knockdown inhibited proliferation, migration and invasion, and increased apoptosis, which was rescued by miR-15b inhibitor. H19 knockdown suppressed CDC42/PAK1 pathway and EMT progress.

CONCLUSION

H19 knockdown inhibited proliferation, migration and invasion, and promoted apoptosis of HCC cells via targeting miR-15b/CDC42/PAK1 axis.

LncRNA n335586/miR-924/CKMT1A axis contributes to cell migration and invasion in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide and chronic hepatitis B virus (HBV) infection is a major risk factor for HCC. Emerging evidences indicate that long noncoding RNAs (lncRNAs) play a pivotal role in HCC development, but its contribution to HBV-related HCC remains largely unclear. Differentially expressed lncRNAs in HBV-related HCC tissues were identified by deep sequencing in our previous study. The function of lncRNA n335586, one of most up-regulated lncRNAs in HBV-related HCC, was characterized in the present study. We found that the expression of n335586 was significantly increased in HBV positive HCC tissues and cells and was induced by HBV in vitro. Function study indicated that lncRNA n335586 remarkably promoted HCC cells migration, invasion and epithelial-mesenchymal transition (EMT) in vitro and metastasis in vivo. Further mechanistic studies showed lncRNA n335586 promoted HCC cells migration and invasion through facilitating the expression of its host gene CKMT1A by competitively binding miR-924. In conclusion, we demonstrated that the n335586/miR-924/CKMT1A axis contributes to HCC cell migration and invasion, which may be helpful for understanding of pathogenesis of HBV-related HCC.

Emerging role of exosome-derived long non-coding RNAs in tumor microenvironment

Exosomes are extracellular vesicles released by many cell types and have been attributed for their roles in many diseases including cancer. Exosomes secreted by tumor cells and stromal cells are critical mediators of intercellular communication in tumor microenvironments. Long noncoding RNAs (lncRNAs) are selectively sorted into exosomes and can regulate cancer onset and progression in a variety of ways. In this review, we summarize the characteristics of exosomal lncRNAs and their dysregulation in multiple types of cancer. We provide an overview of current research on exosomal lncRNAs in tumor microenvironments, especially the functions of exosomal lncRNAs in regulating tumor biology. A deeper understanding of the role of exosomal lncRNAs in the tumor microenvironment may help provide new diagnostic and prognostic markers for cancer.

LncRNA FUNDC2P4 down-regulation promotes epithelial-mesenchymal transition by reducing E-cadherin expression in residual hepatocellular carcinoma after insufficient radiofrequency ablation

PURPOSE

Hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA) could induce epithelial-mesenchymal transition (EMT) in residual tumours, resulting in rapid and aggressive recurrence. However, the role of EMT-related Long noncoding RNAs (lncRNAs) in residual tumour progression remains unclear.

METHODS

Insufficient RFA was simulated in vitro by heating Huh7 cells in water bath at 47 °C, named as Huh7-H. Cell invasion, migration assays and wound healing assay were conducted for functional analysis. Cell proliferation was determined by CCK8 assay. Differential expression profile of EMT-related lncRNAs between Huh7-H and Huh7 was analysed by LncPath human EMT array, and validated by qRT-PCR. Gain/loss-of-function assays of selected lncRNA were conducted by over-expressing or silencing its expression.

RESULTS

Huh7-H presented characteristic EMT morphological changes. WB analysis showed significantly decreased E-cadherin in Huh7-H cells. Transwell assays indicated the abilities of Huh7-H cells in migration and invasion were evidently strengthened. A new lncRNA, FUNDC2P4, was identified by LncPath human EMT array to be significantly down-regulated in Huh7-H cells. In vitro studies showed overexpression of FUNDC2P4 inhibited proliferation, invasion and migration potential and up-regulated E-cadherin expression in SMMC-7721 cells, whereas silencing FUNDC2P4 promoted these potentials and down-regulated E-cadherin expression in Huh7 cells.

CONCLUSIONS

We explored that lncRNA FUNDC2P4 down-regulation promoted EMT leading to tumour proliferation, invasion and migration by reducing E-cadherin expression in residual HCC after insufficient RFA in vitro. These results suggest that FUNDC2P4 may have potentially therapeutic value for prevention and treatment of HCC recurrence after RFA in the future.

Hepatitis B virus x protein induces epithelial-mesenchymal transition of hepatocellular carcinoma cells by regulating long non-coding RNA

BACKGROUND

It has been widely accepted that hepatitis B virus X protein (HBx) plays an important role in hepatocellular carcinoma (HCC). This study aimed to explore the function of long non-coding RNAs (lncRNAs) in the epithelial-mesenchymal transition (EMT) induced by HBx.

METHODS

The association between HBx and EMT markers was detected using immunohistochemistry in HCC tissues. The effect of HBx on HCC EMT was assessed through morphological analysis, transwell assay, metastatic in vivo study and detection of EMT markers. LncRNA microarray was used to screen the differently expressed lncRNAs. Small interfering RNA and Western blot were used to analyse the function and mechanism of the locked lncRNA.

RESULTS

HBx was negatively correlated with the epithelial marker E-cadherin but positively correlated with the mesenchymal marker vimentin in HCC tissues. HBx induced the mesenchymal phenotype and improved the metastatic ability of HCC cells. Meanwhile, HBx down-regulated E-cadherin, whereas it up-regulated vimentin. In HCC cells, HBx altered the expression of 2002 lncRNAs by more than 2-fold. One of them was ZEB2-AS1. Inhibition of ZEB2-AS1 can compensate for the EMT phenotype and reverse the expression of EMT markers regulated by HBx. Additionally, HBx affected the Wnt signalling pathway.

CONCLUSIONS

HBx promotes HCC cell metastasis by inducing EMT, which is at least partly mediated by lncRNAs.

LincRNA-p21 inhibits invasion and metastasis of hepatocellular carcinoma through miR-9/E-cadherin cascade signaling pathway molecular mechanism

In the previous study, it was found that long intergenic noncoding RNA-p21 (lincRNA-p21) was downregulated in hepatocellular carcinoma (HCC) and lincRNA-p21 overexpression inhibited tumor invasion through inducing epithelial–mesenchymal transition. However, the underlying mechanism was not fully elaborated. In this study, lincRNA-p21 expression was measured in 12 paired HCC and nontumor adjacent normal tissues by quantitative real-time polymerase chain reaction. The effects of lincRNA-p21 on HCC cells were studied using lentivirus expressing lincRNA-p21 vector in vitro. The association between lincRNA-p21 level and miR-9 level was tested with the Spearman rank correlation. The effects of miR-9 on HCC cells were studied by using miR-9 inhibitor in vitro. Luciferase assay was used to validate the target of miR-9. The results showed that lincRNA-p21 was downregulated in human HCC tissues and cell lines. LincRNA-p21 overexpression significantly inhibited HCC cell migration and invasion in vitro. Besides, lincRNA-p21 negatively regulated miR-9 expression level, and miR-9 was upregulated in human HCC tissues and cells. MiR-9 knockdown inhibited HCC cell migration and invasion in vitro. Finally, the luciferase assay results showed that E-cadherin was a direct target of miR-9. The expression level of E-cadherin was found to be regulated by lincRNA-p21 and miR-9. Altogether, the results suggested that lincRNA-p21 inhibits migration and invasion of HCC cells through regulating miR-9-mediated E-cadherin cascade signaling pathway.

High expression of long noncoding RNA HULC is a poor predictor of prognosis and regulates cell proliferation in glioma

PURPOSE

Emerging studies show that long noncoding RNAs (lncRNAs) have important roles in carcinogenesis. This study investigated the role of lncRNA highly upregulated in liver cancer (HULC) expression in glioma and its clinical significance in glioma patients.

MATERIALS AND METHODS

HULC expression was detected in glioma tissues and cell lines by using real-time quantitative reverse transcription polymerase chain reactions. Association between HULC levels and clinicopathological factors and patients prognosis was also analyzed. Expression of HULC was restored and knocked down in glioma cell line U87 by using HULC cDNA and siRNA, respectively. CCK-8 and colony formation assays were used to investigate the role of HULC in the regulation of proliferation of glioma cells.

RESULTS

HULC was highly expressed in glioma tissues, being closely related to age and grade of glioma. Univariate survival analysis demonstrated that high HULC levels were significantly associated with overall survival (OS) (hazard ratio [HR], 0.422; 95% confidence interval [CI], 0.220-0.806; P=0.009), and it remained an independent predictor for OS (HR, 0.340; 95% CI, 0.175-0.659; P=0.001) in multivariate Cox regression analysis. Functionally, forced expression of HULC results in increased cell proliferation and colony formation of U87 glioma cell line, whereas knockdown of HULC expression reduced these oncogenic properties of glioma cells.

CONCLUSION

These findings suggest that HULC may play an important role in glioma progression and will be further evaluated as a biomarker for predicting the survival of glioma patients.

LncRNA HULC enhances epithelial-mesenchymal transition to promote tumorigenesis and metastasis of hepatocellular carcinoma via the miR-200a-3p/ZEB1 signaling pathway

Highly upregulated in liver cancer (HULC), a lncRNA that is considered a key molecule in human liver cancer, has recently been revealed to be involved in hepatocellular carcinoma (HCC) development and progression [1, 2]. It has been reported that HULC can promote tumor invasion and metastasis of HCC, but its function and mechanism of action in HCC have not been elucidated. In this study, we found that HULC was aberrantly up-regulated in HCC tissues and associated with TNM stage, intrahepatic metastases, HCC recurrence, and postoperative survival. HULC depletion inhibited the growth and metastasis of HCC cell lines in vitro and in vivo. Moreover, HULC contributes to ZEB1-induced epithelial-mesenchymal transition (EMT), a requirement for tumor invasion and metastasis that plays a key role in cancer progression. This effect of ZEB1 was inhibited by HULC siRNA. We conclude that the HULC functioned as a competing endogenous RNA (ceRNA) to mediate EMT via up-regulating ZEB1. In this way, it sequesters the miR-200a-3p signaling pathway to facilitate HCC metastasis. HULC comes into play as an oncogene in HCC, acting mechanistically by inducing HCC cells to activate EMT. Such an effect promotes tumor progression and metastasis through the miR-200a-3p/ZEB1 signaling pathway. The identification of this novel pathway that links high expression levels of HULC with EMT in HCC cells may serve as the foundation for the development of novel anti-tumor therapeutics.

LncRNAs and cancer

Long non-coding RNAs (lncRNAs) are a group of non-coding RNAs composed of >200 nucleotides. Recent studies have revealed that lncRNAs exert an important role in the development and progression of cancer. In this review, the involvement of the most extensively investigated lncRNAs in cancers of the digestive, respiratory, reproductive, urinary and central nervous systems are discussed. LncRNAs function via molecular and biochemical mechanisms that include cis- and trans-regulation of gene expression, epigenetic modulation in the nucleus and post-transcriptional control in the cytoplasm. Although the detailed biological functions and molecular mechanisms of the majority of lncRNAs remain to be elucidated, this review aims to provide a novel insight into the diagnosis and treatment of cancer using lncRNAs.

Circulating microRNAs as Potential Biomarkers in Non-Alcoholic Fatty Liver Disease and Hepatocellular Carcinoma

Obesity and metabolic syndrome are growing epidemics worldwide and greatly responsible for many liver diseases, including nonalcoholic fatty liver disease (NAFLD). NAFLD often progresses to cirrhosis, end-stage liver failure and hepatocellular carcinoma (HCC), the most common primary liver cancer and one of the leading causes for cancer-related deaths globally. Currently available tools for the diagnosis of NAFLD staging and progression towards HCC are largely invasive and of limited accuracy. In light of the need for more specific and sensitive noninvasive molecular markers, several studies have assessed the potential of circulating microRNAs (miRNAs) as biomarkers of liver injury and hepatocarcinogenesis. Indeed, extracellular miRNAs are very stable in the blood, can be easily quantitated and are differentially expressed in response to different pathophysiological conditions. Although standardization procedures and larger, independent studies are still necessary, miRNAs constitute promising, clinically-useful biomarkers for the NAFLD-HCC spectrum.

Extracellular vesicle long noncoding RNA as potential biomarkers of liver cancer

Analysis of extracellular vesicles (EV) and their contents may be useful as disease biomarkers if they reflect the contents of cells of origin, differ between normal and diseased tissue and can be reliably detected. An increasing number of long noncoding RNA (lncRNA) are being reported to be aberrantly expressed in human cancers. These tumor-associated lncRNA may have potential as new biomarkers of disease. In this review, we highlight lncRNAs that are commonly associated with hepatocellular cancer, and summarize their potential biological roles and underlying molecular mechanisms. While lncRNA can be detected in the circulation, their low expression within circulating vesicles will require the use of highly sensitive detection technologies such as digital polymerase chain reaction or next-generation sequencing. While the integrity and functional role of tumor-specific lncRNAs within EV have yet to be established, their presence or enrichment within tumor cell-derived EV offers promise for their potential as disease biomarkers.

The role of lncRNAs in hepatocellular carcinoma: opportunities as novel targets for pharmacological intervention

Long non-coding RNA (lncRNA) is commonly defined as an RNA with a length of greater than 200 nucleotides, frequently up to 100 kb. Numerous studies have shown that dysregulation of lncRNAs may directly relate to a number of human diseases, particularly in oncology where lncRNAs appear to play an important role. LncRNAs may also play a potentially novel and critical role in the development and progression of hepatocellular carcinoma (HCC). This article discusses lncRNAs as a new possibility for diagnostic and therapeutic approaches for HCC. The authors introduce the relationship between some lncRNAs and HCC, including carcinogenesis, development, metastasis and prognosis. In addition, the authors suggest that the discovery of lncRNAs may encourage the discovery and development of new therapeutic modalities for HCC and that their regulation may be a promising potential treatment for HCC. Clinical studies are required to determine the therapeutic effect of regulating lncRNA in humans with HCC.

Long noncoding RNAs and tumorigenesis: genetic associations, molecular mechanisms, and therapeutic strategies

The human genome contains a large number of nonprotein-coding sequences. Recently, new discoveries in the functions of nonprotein-coding sequences have demonstrated that the "Dark Genome" significantly contributes to human diseases, especially with regard to cancer. Of particular interest in this review are long noncoding RNAs (lncRNAs), which comprise a class of nonprotein-coding transcripts that are longer than 200 nucleotides. Accumulating evidence indicates that a large number of lncRNAs exhibit genetic associations with tumorigenesis, tumor progression, and metastasis. Our current understanding of the molecular bases of these lncRNAs that are associated with cancer indicate that they play critical roles in gene transcription, translation, and chromatin modification. Therapeutic strategies based on the targeting of lncRNAs to disrupt their expression or their functions are being developed. In this review, we briefly summarize and discuss the genetic associations and the aberrant expression of lncRNAs in cancer, with a particular focus on studies that have revealed the molecular mechanisms of lncRNAs in tumorigenesis. In addition, we also discuss different therapeutic strategies that involve the targeting of lncRNAs.

CD90+ liver cancer cells modulate endothelial cell phenotype through the release of exosomes containing H19 lncRNA

Background

CD90+ liver cancer cells have been described as cancer stem-cell-like (CSC), displaying aggressive and metastatic phenotype. Using two different in vitro models, already described as CD90+ liver cancer stem cells, our aim was to study their interaction with endothelial cells mediated by the release of exosomes.

Methods

Exosomes were isolated and characterized from both liver CD90+ cells and hepatoma cell lines. Endothelial cells were treated with exosomes, as well as transfected with a plasmid containing the full length sequence of the long non-coding RNA (lncRNA) H19. Molecular and functional analyses were done to characterize the endothelial phenotype after treatments.

Results

Exosomes released by CD90+ cancer cells, but not by parental hepatoma cells, modulated endothelial cells, promoting angiogenic phenotype and cell-to-cell adhesion. LncRNA profiling revealed that CD90+ cells were enriched in lncRNA H19, and released this through exosomes. Experiments of gain and loss of function of H19 showed that this LncRNA plays an important role in the exosome-mediated phenotype of endothelial cells.

Conclusions

Our data indicate a new exosome-mediated mechanism by which CSC-like CD90+ cells could influence their tumor microenvironment by promoting angiogenesis. Moreover, we suggest the lncRNA H19 as a putative therapeutic target in hepatocellular carcinoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0426-x) contains supplementary material, which is available to authorized users.

Alcoholic, Nonalcoholic, and Toxicant-Associated Steatohepatitis: Mechanistic Similarities and Differences

Hepatic steatosis and steatohepatitis are common histologic findings that can be caused by multiple etiologies. The three most frequent causes for steatosis/steatohepatitis are alcohol (alcoholic steatohepatitis, ASH), obesity/metabolic syndrome (nonalcoholic steatohepatitis, NASH), and environmental toxicants (toxicant-associated steatohepatitis, TASH). Hepatic steatosis is an early occurrence in all three forms of liver disease, and they often share common pathways to disease progression/severity. Disease progression is a result of both direct effects on the liver as well as indirect alterations in other organs/tissues such as intestine, adipose tissue, and the immune system. Although the three liver diseases (ASH, NASH, and TASH) share many common pathogenic mechanisms, they also exhibit distinct differences. Both shared and divergent mechanisms can be potential therapeutic targets. This review provides an overview of selected important mechanistic similarities and differences in ASH, NASH, and TASH.

LncRNAs and neoplasia

Long noncoding RNAs are emerging as new mediators of tumorigenesis by virtue of their various functions and their capacity to induce different mechanisms as a result of their wide spectrum of interactions. They play critical roles in a broad range of cellular processes including regulation of gene expression, imprinting, chromatin modification, transcription and posttranslational processing. Expression and activity of lncRNAs are deregulated in several types of human cancer. Impairment of lncRNA activity may affect key components of the cellular gene regulatory networks and is associated with deregulation of a large number of cellular oncogenic pathways. LncRNAs are also being evaluated as diagnostic and prognostic biomarkers and may provide targets for potential therapeutic applications. An improved understanding of the roles played by lncRNAs in cancer will lead to more effective therapeutic strategies. In this review we summarize the current knowledge on lncRNAs and their function as mediators of tumor development.