Identification and Functional Characterization of Long Non-coding RNA MIR22HG as a Tumor Suppressor for Hepatocellular Carcinoma

LncRNAs in the Type I Interferon Antiviral Response

The proper functioning of the immune system requires a robust control over a delicate equilibrium between an ineffective response and immune overactivation. Poor responses to viral insults may lead to chronic or overwhelming infection, whereas unrestrained activation can cause autoimmune diseases and cancer. Control over the magnitude and duration of the antiviral immune response is exerted by a finely tuned positive or negative regulation at the DNA, RNA, and protein level of members of the type I interferon (IFN) signaling pathways and on the expression and activity of antiviral and proinflammatory factors. As summarized in this review, committed research during the last decade has shown that several of these processes are exquisitely regulated by long non-coding RNAs (lncRNAs), transcripts with poor coding capacity, but highly versatile functions. After infection, viruses, and the antiviral response they trigger, deregulate the expression of a subset of specific lncRNAs that function to promote or repress viral replication by inactivating or potentiating the antiviral response, respectively. These IFN-related lncRNAs are also highly tissue- and cell-type-specific, rendering them as promising biomarkers or therapeutic candidates to modulate specific stages of the antiviral immune response with fewer adverse effects.

HRG switches TNFR1-mediated cell survival to apoptosis in Hepatocellular Carcinoma

Background: Tumor necrosis factor receptor 1 (TNFR1) signaling plays a pleiotropic role in the development of hepatocellular carcinoma (HCC). The formation of TNFR1-complex I supports cell survival while TNFR1-complex II leads to apoptosis, and the underlying mechanisms of the transformation of these TNFR1 complexes in HCC remain poorly defined. Methods: The interaction protein of TNFR1 was identified by GST pulldown assay, immunoprecipitation and mass spectrometry. In vitro and in vivo assay were performed to explore the biological features and mechanisms underlying the regulation of TNFR1 signals by histidine-rich glycoprotein (HRG). Data from the public databases and HCC samples were utilized to analyze the expression and clinical relevance of HRG. Results: HRG directly interacted with TNFR1 and stabilized TNFR1 protein by decreasing the Lys(K)-48 ubiquitination mediated-degradation. The formation of TNFR1-complex II was prompted by HRG overexpression via upregulating Lys(K)-63 ubiquitination of TNFR1. Besides, overexpression of HRG suppressed expression of pro-survival genes by impairing the activation of NF-κB signaling in the presence of TNFR1. Moreover, downregulation of HRG was a result of feedback inhibition of NF-κB activation in HCC. In line with the pro-apoptotic switch of TNFR1 signaling after HRG induction, overexpression of HRG inhibited cell proliferation and increased apoptosis in HCC. Conclusions: Our findings illustrate a crucial role for HRG in suppressing HCC via inclining TNFR1 to a pro-apoptotic cellular phenotype. Restoring HRG expression in HCC tissues might be a promising pharmacological approach to blocking tumor progression by shifting cellular fate from cell survival to apoptosis.

Interfering with long non-coding RNA MIR22HG processing inhibits glioblastoma progression through suppression of Wnt/β-catenin signalling

Long non-coding RNAs play critical roles in tumour progression. Through analysis of publicly available genomic datasets, we found that MIR22HG, the host gene of microRNAs miR-22-3p and miR-22-5p, is ranked among the most dysregulated long non-coding RNAs in glioblastoma. The main purpose of this work was to determine the impact of MIR22HG on glioblastoma growth and invasion and to elucidate its mechanistic function. The MIR22HG/miR-22 axis was highly expressed in glioblastoma as well as in glioma stem-like cells compared to normal neural stem cells. In glioblastoma, increased expression of MIR22HG is associated with poor prognosis. Through a number of functional studies, we show that MIR22HG silencing inhibits the Wnt/β-catenin signalling pathway through loss of miR-22-3p and -5p. This leads to attenuated cell proliferation, invasion and in vivo tumour growth. We further show that two genes, SFRP2 and PCDH15, are direct targets of miR-22-3p and -5p and inhibit Wnt signalling in glioblastoma. Finally, based on the 3D structure of the pre-miR-22, we identified a specific small-molecule inhibitor, AC1L6JTK, that inhibits the enzyme Dicer to block processing of pre-miR-22 into mature miR-22. AC1L6JTK treatment caused an inhibition of tumour growth in vivo. Our findings show that MIR22HG is a critical inducer of the Wnt/β-catenin signalling pathway, and that its targeting may represent a novel therapeutic strategy in glioblastoma patients.

MiR-22 as a metabolic silencer and liver tumor suppressor

With obesity rate consistently increasing, a strong relationship between obesity and fatty liver disease has been discovered. More than 90% of bariatric surgery patients also have non-alcoholic fatty liver diseases (NAFLDs). NAFLD and non-alcoholic steatohepatitis (NASH), which are the hepatic manifestations of metabolic syndrome, can lead to liver carcinogenesis. Unfortunately, there is no effective medicine that can be used to treat NASH or liver cancer. Thus, it is critically important to understand the mechanism underlying the development of these diseases. Extensive evidence suggests that microRNA 22 (miR-22) can be a diagnostic marker for liver diseases as well as a treatment target. This review paper focuses on the roles of miR-22 in metabolism, steatosis, and liver carcinogenesis. Literature search is limited based on the publications included in the PubMed database in the recent 10 years.

MIR22HG acts as a tumor suppressor via TGFβ/SMAD signaling and facilitates immunotherapy in colorectal cancer

Background

Long noncoding RNAs (lncRNAs) are emerging as critical regulatory elements and play fundamental roles in the biology of various cancers. However, we are still lack of knowledge about their expression patterns and functions in human colorectal cancer (CRC).

Methods

Differentially expressed lncRNAs in CRC were identified by bioinformatics screen and the level of MIR22HG in CRC and control tissues were determined by qRT-PCR. Cell viability and migration capacities were examined by MTT and transwell assay. Mouse model was used to examine the function and rational immunotherapy of MIR22HG in vivo.

Results

We systematically investigated the expression pattern of lncRNAs and revealed MIR22HG acts as a tumor suppressor in CRC. The expression of MIR22HG was significantly decreased in CRC, which was mainly driven by copy number deletion. Reduced expression of MIR22HG was significantly associated with poor overall survival. Silencing of MIR22HG promoted cell survival, proliferation and tumor metastasis in vitro and in vivo. Mechanistically, MIR22HG exerts its tumor suppressive activity by competitively interacting with SMAD2 and modulating the activity of TGFβ pathway. Decreased MIR22HG promoted the epithelial-mesenchymal transition in CRC. Importantly, we found that MIR22HG expression is significantly correlated with CD8A and overexpression of MIR22HG triggers T cell infiltration, enhancing the clinical benefits of immunotherapy.

Conclusion

MIR22HG acts as a tumor suppressor in CRC. Our data provide mechanistic insights into the regulation of MIR22HG in TGFβ pathway and facilitates immunotherapy in cancer.

Human antigen R: A potential therapeutic target for liver diseases

Human antigen R (HuR), also known as HuA and embryonic lethal abnormal vision-like 1 (ELAVL1), is a ubiquitously expressed RNA binding protein and functions as an RNA regulator and mediates the expression of various proteins by diverse post-transcriptional mechanisms. HuR has been well characterized in the inflammatory responses and in the development of various cancers. The importance of HuR-mediated roles in cell signaling, inflammation, fibrogenesis and cancer development in the liver has attracted a great deal of attention. However, there is still a substantial gap between the current understanding of the potential roles of HuR in the progression of liver disease and whether HuR can be targeted for the treatment of liver diseases. In this review, we introduce the function and mechanistic characterization of HuR, and then focus on the physiopathological roles of HuR in the development of different liver diseases, including hepatic inflammation, alcoholic liver diseases, non-alcoholic fatty liver diseases, viral hepatitis, liver fibrosis and liver cancers. We also summarize existing approaches targeting HuR function. In conclusion, although characterizing the liver-specific HuR function and demonstrating the multi-level regulative networks of HuR in the liver are still required, emerging evidence supports the notion that HuR represents a potential therapeutic target for the treatment of chronic liver diseases.

The Emerging Role of Long Non-Coding RNAs in the Metastasis of Hepatocellular Carcinoma

Long non-coding RNAs (lncRNAs) play multifaceted roles in modulating gene expression under both physiological and pathological processes. The dysregulation of lncRNAs has been increasingly linked with many human diseases, including a plethora of cancers. Mounting evidence indicates that lncRNAs are aberrantly expressed in hepatocellular carcinoma (HCC) and can regulate HCC progression, as well as metastasis. In this review, we summarize the recent findings on the expanding roles of lncRNAs in modulating various functions of HCC, and elaborate on how can lncRNAs impact HCC metastasis and progression via interacting with chromatin, RNA, and proteins at the epigenetic, transcriptional, and post-transcriptional levels. This mini-review also highlights the current advances regarding the signaling pathways of lncRNAs in HCC metastasis and sheds light on the possible application of lncRNAs for the prevention and treatment of HCC.

DUXAP8 a Pan-Cancer Prognostic Marker Involved in the Molecular Regulatory Mechanism in Hepatocellular Carcinoma: A Comprehensive Study Based on Data Mining, Bioinformatics, and in vitro Validation

Background

Double homeobox A pseudogene 8 (DUXAP8) has been identified as a key regulator at the posttranscriptional level in various types of cancers. However, whether DUXAP8 has a role in hepatocellular carcinoma (HCC) progression remains to be determined. Here, we aimed to investigate the potential clinical value of DUXAP8 as a pan-cancer marker, and its role in HCC development through an integrated analysis strategy and in vitro experimental validation.

Methods

Comprehensive analysis was performed using data mined from public databases to evaluate the expression patterns and clinical value of DUXAP8 in human pan-cancers. Bioinformatics analysis was performed to investigate the potential biological functions of DUXAP8 in HCC based on TCGA database. Real-time qPCR analysis was used to examine the expression levels of DUXAP8 in HCC tissue samples and cell lines. DUXAP8-siRNA was used to silence DUXAP8 in the Hep-G2 cell line to examine the role of DUXAP8 in HCC cell proliferation and invasion.

Results

DUXAP8 was significantly upregulated in various types of human cancers and could serve as a potential pan-cancer diagnostic and prognostic biomarker. Bioinformatics analysis suggested that DUXAP8 might be involved in the regulation of the biological processes of HCC cell cycle, cell division and cell proliferation. Additionally, downregulation of DUXAP8 inhibited HCC cell proliferation and invasion in vitro.

Conclusion

This study revealed that DUXAP8 may serve as a potential pan-cancer prognostic and diagnostic marker in humans. In addition, DUXAP8 promoted HCC cell proliferation and invasion, suggesting that it may represent a novel therapeutic target for HCC.

Long Non-coding RNA LOXL1-AS1 Drives Breast Cancer Invasion and Metastasis by Antagonizing miR-708-5p Expression and Activity

LOXL1-AS1, a recently characterized long non-coding RNA (lncRNA), has been reported to modulate tumor progression in several types of cancer. However, the expression and role of LOXL1-AS1 in breast cancer remain unclear. In this study, we sought to identify novel lncRNA regulators engaged in breast cancer metastasis. To this end, we examined 42 cancer-related lncRNAs between MCF7 (with low metastatic potential) and MDA-MB-231 (with high metastatic potential) cells. These lncRNAs have been found to affect the invasiveness of several cancer types, but they are still undefined in breast cancer. Among the 42 candidates, LOXL1-AS1 is significantly increased in MDA-MB-231 cells relative to MCF7 cells. We also show that LOXL1-AS1 is upregulated in breast cancer tissues and cells compared to noncancerous counterparts. Increased LOXL1-AS1 expression is correlated with tumor stage and lymph node metastasis in breast cancer patients. Biologically, overexpression of LOXL1-AS1 enhances and knockdown of LOXL1-AS1 suppresses breast cancer cell migration and invasion. In vivo studies demonstrate that depletion of LOXL1-AS1 inhibits breast cancer metastasis. Mechanistically, LOXL1-AS1 sponges miR-708-5p to increase nuclear factor κB (NF-κB) activity. LOXL1-AS1 can also interact with EZH2 protein to enhance EZH2-mediated transcriptional repression of miR-708-5p. Rescue experiments indicate that co-expression of miR-708-5p attenuates LOXL1-AS1-induced invasiveness in breast cancer. In addition, there is a negative correlation between LOXL1-AS1 and miR-708-5p expression in breast cancer specimens. Overall, LOXL1-AS1 upregulation facilitates breast cancer invasion and metastasis by blocking miR-708-5p expression and activity. LOXL1-AS1 serves as a potential therapeutic target for breast cancer treatment.

MIR22HG As A Tumor Suppressive lncRNA In HCC: A Comprehensive Analysis Integrating RT-qPCR, mRNA-Seq, And Microarrays

Introduction

MIR22HG has a reported involvement in the tumorigenesis of a variety of cancers, including hepatocellular carcinoma (HCC). However, the exact molecular mechanism of MIR22HG in HCC has not been clarified.

Methods

In the present study, we integrated data from in-house RT-qPCR, RNA-sequencing, microarray, and literature studies to conduct a comprehensive evaluation of the clinico-pathological and prognostic significance of MIR22HG in an extremely large group of HCC samples. We also explored the potential mechanism of MIR22HG in HCC by analyzing the alteration profiles of MIR22HG in HCC to predict transcription factors (TFs) that may interact with MIR22HG and to annotate the biological functions of genes co-expressed with MIR22HG. MIR22HG expression was also compared in HCC nude mice xenografts before and after a treatment with nitidine chloride.

Results

We found that MIR22HG was downregulated in HCC and that this downregulation correlated with the malignant phenotype of HCC. Comprehensive analysis of the prognostic impact of MIR22HG in HCC revealed a beneficial effect of MIR22HG on the survival outcome of HCC patients. Seven cases of MIR22HG deep deletion occurred in 360 of the cancer genome atlas (TCGA) provisional HCC samples. A total of 22 MIR22HG-TF-mRNA triplets in HCC were predicted by the lncRNAmap. Co-expressed genes of MIR22HG, identified by weighted correlation network analysis (WGCNA), mainly participated in the pathways involving osteoclast differentiation, chemokine signaling pathways, and hematopoietic cell lineage. In vivo experiments demonstrated that nitidine chloride could stimulate MIR22HG expression in HCC xenografts.

Conclusion

In summary, MIR22HG may play a tumor-suppressive role in HCC by coordinating with predicted TFs and co-expressed genes, such as NLRP3, CSF1R, SIGLEC10, and ZEB2, or by being controlled by nitidine chloride.

Prolyl hydroxylase substrate adenylosuccinate lyase is an oncogenic driver in triple negative breast cancer

Protein hydroxylation affects protein stability, activity, and interactome, therefore contributing to various diseases including cancers. However, the transiency of the hydroxylation reaction hinders the identification of hydroxylase substrates. By developing an enzyme-substrate trapping strategy coupled with TAP-TAG or orthogonal GST- purification followed by mass spectrometry, we identify adenylosuccinate lyase (ADSL) as an EglN2 hydroxylase substrate in triple negative breast cancer (TNBC). ADSL expression is higher in TNBC than other breast cancer subtypes or normal breast tissues. ADSL knockout impairs TNBC cell proliferation and invasiveness in vitro and in vivo. An integrated transcriptomics and metabolomics analysis reveals that ADSL activates the oncogenic cMYC pathway by regulating cMYC protein level via a mechanism requiring ADSL proline 24 hydroxylation. Hydroxylation-proficient ADSL, by affecting adenosine levels, represses the expression of the long non-coding RNA MIR22HG, thus upregulating cMYC protein level. Our findings highlight the role of ADSL hydroxylation in controlling cMYC and TNBC tumorigenesis.

LINC00978 promotes the progression of hepatocellular carcinoma by regulating EZH2-mediated silencing of p21 and E-cadherin expression

Long non-coding RNAs (lncRNAs) have been suggested as important regulators of cancer development and progression in hepatocellular carcinoma (HCC). Nevertheless, the clinical value and biological roles of LINC00978 in HCC remain unclear. In this study, we detected the expression of LINC00978 in tumor tissues and serum of HCC patients, examined the roles of LINC00978 in HCC progression and elucidated the underlying molecular mechanisms. We found that LINC00978 expression was upregulated in tumor tissues and serum of HCC patients. Higher serum levels of LINC00978 could distinguish HCC patients from hepatitis and liver cirrhosis patients and healthy controls. LINC00978 knockdown inhibited HCC cell proliferation, migration and invasion while promoted cell cycle arrest and apoptosis. Overexpression of LINC00978 led to the opposite effects. LINC00978 knockdown also inhibited HCC growth and metastasis in mouse tumor models. Mechanistically, LINC00978 bound to EZH2 and mediated its accumulation at the promoter region of p21 and E-cadherin genes, leading to the trimethylation of H27K3 and the inhibition of p21 and E-cadherin expression. Moreover, the simultaneous depletion of p21 and E-cadherin expression reversed the inhibitory effects of LINC00978 knockdown on HCC cell proliferation, migration, and invasion. Taken together, these findings suggest that LINC00978 promotes HCC progression by inhibiting p21 and E-cadherin expression via EZH2-mediated epigenetic silencing. LINC00978 may represent a novel biomarker for HCC diagnosis, prognosis, and therapy.

lncRNA SNHG6 functions as a ceRNA to up-regulate c-Myc expression via sponging let-7c-5p in hepatocellular carcinoma

Emerging evidence has revealed that dysregulation of lncRNAs correlate with the development and progression of hepatocellular carcinoma (HCC). In the present study, we globally investigated the expression of SNHG6 in 31 cancer type, and we found that SNHG6 was highly expressed in various cancers, especially in HCC. High expression of SNHG6 was associated with progression and poor prognosis in patients with HCC. Gain of function and loss of function assays showed that SNHG6 promoted HCC cell proliferation. Gene Set Enrichment Analysis (GSEA) and correlation analysis suggested that SNHG6 positively correlated with c-Myc and its downstream targets. Ectopic overexpression of SNHG6 markedly increased the expression of c-Myc and its downstream targets, whereas silencing SNHG6 had the opposite effect on the expression of c-Myc and its downstream targets. Mechanistic assays revealed that SNHG6 acted as a competing endogenous RNA (ceRNA) to sponge let-7c-5p and thereby modulating the depression of c-Myc by let-7c-5p. Taken together, SNHG6 promotes HCC cell proliferation via competitively binding let-7c-5p in hepatocellular carcinoma.

Chromobox homolog 8 (CBX8) Interacts with Y-Box binding protein 1 (YBX1) to promote cellular proliferation in hepatocellular carcinoma cells

Polycomb group (PcG) proteins have recently been identified as critical regulators in tumor initiation and development. However, the function of CBX8 in human hepatocellular carcinoma (HCC) remains largely unknown. Our study was designed to explore the biological function and clinical implication of CBX8 in HCC. We investigated the interplay between CBX8 and cell cycle through Gene Set Enrichment Analysis and western blotting. Bioinformatics tools and co-immunoprecipitation were used to explore cell cycle regulation. Finally, we studied the expression and clinical significance of CBX8 in HCC through 3 independent datasets. CBX8 was upregulated in HCC and its expression correlated with cell cycle progression. CyclinD1 was downregulated by CBX8 knockdown but upregulated by CBX8 overexpression. YBX1 interacted with CBX8 and regulated the cell cycle. Moreover, targeting YBX1 with specific siRNA impaired CBX8-mediated regulation of CyclinD1. CBX8 overexpression boosted HCC cell growth, while CBX8 knockdown suppressed cell proliferation. Further, YBX1 interacted with CBX8. YBX1 knockdown compromised the proliferation of CBX8 overexpressing cells. CBX8 promotes HCC cell proliferation through YBX1 mediated cell cycle progression and is related to poor HCC prognoses. Therefore, CBX8 may serve as a potential target for the diagnosis and treatment of HCC.

Discovery of core genes in colorectal cancer by weighted gene co-expression network analysis

The aim of the present study was to investigate the interactions among messenger RNAs (mRNAs), microRNAs (miRNAs), and long noncoding RNAs (lncRNAs) in colorectal cancer (CRC), in order to examine its underlying mechanisms. The raw gene expression data was downloaded from the Gene Expression Omnibus (GEO) database. An online tool, GEO2R, which is based on the limma package, was used to identify differentially expressed genes. The co-expression between lncRNAs and mRNAs was identified utilizing the weighted gene co-expression analysis package of R to construct a coding non-coding (CNC) network. The function of the genes in the CNC network was determined by performing Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways enrichment analysis. The interactions among miRNAs, mRNAs and lncRNAs were predicted using Lncbase and mirWalk to construct the competing endogenous RNA (ceRNA) network. The expression of the genes involved in the ceRNA network was further validated in The Cancer Genome Atlas dataset. A total of 3,183 dysregulated mRNAs, 78 dysregulated miRNAs and 2,248 dysregulated lncRNAs were screened in two GEO datasets. Combined with the results of the dysregulated genes, 169 genes were selected to construct the CNC network. 'p53 signaling pathway' and the 'cell cycle' were the most significant enriched pathways in the genes involved in the CNC network. Finally, a validated ceRNA network composed of 2 lncRNAs (MIR22HG and RP11-61I13.3), 5 miRNAs (hsa-miR-765, hsa-miR-198, hsa-miR-125a-3p, hsa-miR-149-3p and hsa-miR-650) and 5 mRNAs (ANK2, BTK, GBP2, PCSK5 and PDK4) was obtained. In conclusion, MIR22HG may regulate PCSK5, BTK and PDK4, and RP11-61I13.3 may regulate the ANK2, GBP2, PCSK5 through sponging miRNAs to act on the progression of CRC, and the potential function of these genes have been revealed. However, the diagnostic and prognostic value of these genes requires further validation.

Nek2 augments sorafenib resistance by regulating the ubiquitination and localization of β-catenin in hepatocellular carcinoma

BACKGROUND

Sorafenib is the first-line treatment for advanced-stage hepatocellular carcinoma (HCC). Several studies have shown that the up-regulation of β-catenin plays a role in sorafenib resistance in HCC; however, the mechanism associated with this phenomenon remains elusive.

METHODS

Western blotting, flow cytometry, and an evaluation of IC50 values were used to confirm the role of β-catenin in HCC sorafenib resistance. Immunoprecipitation and western blotting were then performed to identify regulatory interactions between β-catenin and Nek2. Further, western blotting, flow cytometry, and an in vivo xenograft model were used to evaluate the function of Nek2 in HCC sorafenib resistance, whereas rescue experiments were performed to confirm that Nek2 induces sorafenib resistance via β-catenin. Finally, western blotting and immunohistochemistry were used to evaluate the expression level of Nek2 in paired HCC and non-tumor tissues.

RESULTS

We showed that β-catenin could suppress sorafenib-induced apoptosis and cell growth inhibition in HCC cell lines. By screening β-catenin-interacting proteins, we found that Nek2 could bind β-catenin in sorafenib-treated HCC cell lines. Our results also showed that Nek2 stabilizes β-catenin and promotes its translocation to the nucleus, consequently activating the transcription of downstream target genes. We further confirmed that Nek2 could induce sorafenib resistance in HCC cell lines, and that β-catenin was the key element involved in this process. Further, a xenograft tumor model showed that Nek2 knockdown could improve the anti-tumor effect of sorafenib, whereas an analysis of tumor proteins showed that Nek2 regulates β-catenin protein levels and its nuclear translocation in vivo. In addition, Nek2 was found to be up-regulated in HCC tissue, and especially in advanced-stage disease.

CONCLUSIONS

Our study proves that Nek2 induces HCC sorafenib resistance via β-catenin and suggests a novel therapeutic strategy to improve the anti-tumor effects of sorafenib in HCC.

LncRNA SNHG16 aggravates tumorigenesis and development of hepatocellular carcinoma by sponging miR-4500 and targeting STAT3

Hepatocellular carcinoma (HCC) is the most common type of primary liver tumor and becomes a lethal malignancy on account of high mortality and increasing incidence. A growing body of studies has proved that long noncoding RNAs (lncRNAs) participate in the development of diverse cancers. Although it has been commonly accepted that SNHG16 is a procancer gene in numerous cancers, the regulatory mechanism of SNHG16 in HCC still needs more explorations. In this study, our results delineated that SNHG16 presented much higher expression levels in HCC tissues and cells, particularly in advanced stages of HCC. Enhanced SNHG16 expression was strongly related to poor prognosis. SNHG16 facilitated HCC progression by promoting cell proliferation, migration, invasion, and epithelial-mesenchymal transition process as well as inhibiting cell apoptosis. SNHG16 served as a sponge for miR-4500 in HCC and miR-4500 neutralized the influences of SNHG16 knockdown on HCC. SNHG16 was confirmed to compete with signal transducer and activator of transcription 3 (STAT3) to bind with miR-4500. SNHG16 aggravated the development of HCC via sponging miR-4500 so as to upregulate STAT3. In other words, this study was the first to investigate the potential mechanism of SNHG16 in HCC and verified SNHG16 exerted its carcinogenesis by miR-4500/STAT3 axis, suggesting SNHG16 may be a new underlying therapeutic target for HCC treatment.

Molecular pattern of lncRNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most notable lethal malignancies worldwide. However, the molecular mechanisms involved in the initiation and progression of this disease remain poorly understood. Over the past decade, many studies have demonstrated the important regulatory roles of long non-coding RNAs (lncRNAs) in HCC. Here, we comprehensively review recent discoveries regarding HCC-associated lncRNA functions, which we have classified and described according to their mechanism models.

LncRNA MIR22HG inhibits growth, migration and invasion through regulating the miR-10a-5p/NCOR2 axis in hepatocellular carcinoma cells

Despite the rapidly identified numbers of lncRNA in humans, exploration of the molecular mechanisms of lncRNA is lagging, because the molecular mechanisms of lncRNA can be various and complex in different conditions. In this study, we found a new molecular mechanism for a versatile molecule, MIR22HG. MIR22HG is an lncRNA that contributes to the initiation and progression of many human cancers, including hepatocellular carcinoma (HCC). We report that MIR22HG was downregulated in 120 HCC samples compared with adjacent nontumor liver tissues. More interestingly, decreased expression of MIR22HG in HCC could predict poor prognosis of HCC patients. Knockdown of MIR22HG promoted the growth, migration and invasion of HCC cells. In exploring the molecular mechanism of MIR22HG, we found that MIR22HG functioned as a tumor suppressor in hepatocellular carcinomas, in part through serving as a competing endogenous RNA to modulate the miRNA‐10a‐5p level. Moreover, NCOR2 was verified to act as the downstream target gene of MIR22HG/miR‐10a‐5p. In addition, the MIR22HG/miRNA‐10a‐5p/NCOR2 axis inhibited the activation of the Wnt/β‐catenin pathway. Together, our results demonstrated that MIR22HG inhibited HCC progression in part through the miR‐10a‐5p/NCOR2 signaling axis and might act as a new prognostic biomarker for HCC patients.

STAT3-induced upregulation of lncRNA ABHD11-AS1 promotes tumour progression in papillary thyroid carcinoma by regulating miR-1301-3p/STAT3 axis and PI3K/AKT signalling pathway

Objectives

Emerging evidences indicated the importance of long non‐coding RNAs (lncRNAs) in the tumorigenesis and deterioration of malignant tumours. To our knowledge, the study about lncRNAs in papillary thyroid carcinoma (PTC) is still inadequate. ABHD11‐AS1 was highly expressed in the PTC samples of The Cancer Genome Atlas database. This study focused on the biological function and mechanism of lncRNA ABHD11‐AS1 in PTC.

Materials and methods

qRT‐PCR analysis was used to examine the expression of ABHD11‐AS1 in PTC tissues and cell lines. The prognostic significance of ABHD11‐AS1 for the patients with PTC was analysed with Kaplan‐Meier analysis. The effects of ABHD11‐AS1 knockdown on the cell proliferation and metastasis were evaluated by in vitro functional assays and in vivo experiments. The molecular mechanism which contributed to the oncogenic role of ABHD11‐AS1 in PTC was explored by conducting mechanism experiments. Rescue assays were carried out for final demonstration.

Results

High expression of ABHD11‐AS1 predicted poor prognosis for patients with PTC and promoted cell proliferation and metastasis in vitro and in vivo. ABHD11‐AS1 was activated by the transcription factor STAT3. ABHD11‐AS1 positively regulated PI3K/AKT signalling pathway. ABHD11‐AS1 acted as a competitive endogenous (ce) RNA to upregulate STAT3 by sponging miR‐1301‐3p.

Conclusions

STAT3‐induced lncRNA ABHD11‐AS1 promoted PTC progression by regulating PI3K/AKT signalling pathway and miR‐1301‐3p/STAT3 axis.

Long noncoding RNA LINC00339 promotes renal tubular epithelial pyroptosis by regulating the miR-22-3p/NLRP3 axis in calcium oxalate-induced kidney stone

This study aims to investigate the role of long noncoding RNA (lncRNA) long intergenic nonprotein coding RNA 339 (LINC00339) in regulating renal tubular epithelial pyroptosis in kidney stones and to explore the underlying mechanism. The human renal proximal tubular epithelial (HK-2) cells were treated with calcium oxalate monohydrate (COM) for 72 hours to establish the cell model of renal tubular injury. Relative expression of LINC00339 and miR-22-3p was measured by real-time quantitative reverse transcription polymerase chain reaction. Expression of pyroptosis-related molecules was measured by Western blot analysis (NLRP3, ASC, and cleaved caspase-1 p10) and enzyme-linked immunosorbent assay (interleukin-1β [IL-1β] and IL-18). Pyroptosis was also determined by lactate dehydrogenase release and active caspase-1-propidium iodide double staining. Luciferase reporter assays were performed to verify whether miR-22-3p could bind to LINC00339 or NLRP3. We observed increased LINC00339, decreased miR-22-3p, NLRP3 inflammasome activation, and enhanced cell pyroptosis in COM-treated HK-2 cells. Furthermore, overexpression of both LINC00339 and NLRP3 activated NLRP3 inflammasome and promoted pyroptosis in COM-treated HK-2 cells, whereas miR-22-3p mimic and NLRP3 knockdown exerted the opposite effects. Mechanically, LINC00339 functioned as a competitive endogenous RNA by sponging miR-22-3p to facilitate NLRP3 expression. In conclusion, lncRNA LINC00339 promotes cell pyroptosis by sponging miR-22-3p to regulate NLRP3 expression in COM-treated HK-2 cells.

Long noncoding RNA GAS5 inhibits metastasis by targeting miR-182/ANGPTL1 in hepatocellular carcinoma

Intrahepatic and extrahepatic metastases are responsible for the majority of hepatocellular carcinoma (HCC)-related mortalities. Long noncoding RNAs (lncRNAs) exert important functions in modulating various tumor behaviors. However, the functions and mechanisms of lncRNAs in HCC metastasis remain largely unknown. In this study, downregulation of lncRNA growth arrest-specific 5 (GAS5) was observed in HCC tissues and cells, and predicted poor prognosis of patients with HCC. Through performing gain- and loss-of-function experiments, we found that GAS5 could obviously inhibit migration and invasion of HCC cells in vitro, and suppress tumor metastasis in vivo. Mechanistically, GAS5 functioned as a tumor suppressor in HCC metastasis through directly interacting with miR-182 and abrogating its oncogenic function in this setting. Moreover, GAS5 acted as a competing endogenous RNA (ceRNA) for miR-182 to upregulate the expression of anti-metastasis protein ANGPTL1. Finally, we demonstrated that using ultrasound targeted microbubble destruction (UTMD)-mediated GAS5 transfection could significantly decrease migratory and invasive abilities of HCC cells. Collectively, our study first reveals the mechanism of GAS5/miR-182/ANGPTL1 axis in suppressing HCC metastasis, which provides promising new avenues for therapeutic intervention against HCC progression.

lncRNA A1BG-AS1 suppresses proliferation and invasion of hepatocellular carcinoma cells by targeting miR-216a-5p

Extensive evidence indicate that long noncoding RNAs (lncRNAs) regulates the tumorigenesis and progression of hepatocellular carcinoma (HCC). However, the expression and biological function of lncRNA A1BG antisense RNA 1 (A1BG-AS1) were poorly known in HCC. Here, we found the underexpression of A1BG-AS1 in HCC via analysis of The Cancer Genome Atlas database. Further analyses confirmed that A1BG-AS1 expression in HCC was markedly lower than that in noncancerous tissues based on our HCC cohort. Clinical association analysis revealed that low A1BG-AS1 expression correlated with poor prognostic features, such as microvascular invasion, high tumor grade, and advanced tumor stage. Follow-up data indicated that low A1BG-AS1 level evidently correlated with poor clinical outcomes of HCC patients. Moreover, forced expression of A1BG-AS1 repressed proliferation, migration, and invasion of HCC cells in vitro. Conversely, A1BG-AS1 knockdown promoted these malignant behaviors in HepG2 cells. Mechanistically, A1BG-AS1 functioned as a competing endogenous RNA by directly sponging miR-216a-5p in HCC cells. Notably, miR-216a-5p restoration rescued A1BG-AS1 attenuated proliferation, migration and invasion of HCCLM3 cells. A1BG-AS1 positively regulated the levels of phosphatase and tensin homolog and SMAD family member 7, which were reduced by miR-216a-5p in HCC cells. Altogether, we conclude that A1BG-AS1 exerts a tumor suppressive role in HCC progression.

Analysis of long non-coding RNA profiled following MC-LR-induced hepatotoxicity using high-throughput sequencing

The occurrence of microcystin-LR(MC-LR) variant a known hepatotoxin constitutes a global public health concern. However, the molecular mechanisms underlying MC-LR-induced hepatotoxicity remain to be determined. The aim of this study was to investigate whether long noncoding RNAs (lncRNA) were involved in MC-LR-mediated hepatotoxicity using human normal liver cell line HL7702 to profile lncRNAs after 24 hr treatment with MC-LR. With the use of high-throughput sequencing techniques, data showed that the expression levels of 37, 33, 34, 35 lncRNA were significantly altered following exposure to 1, 2.5, 5, or 10 μM MC-LR, respectively. In particular, the expression levels of LINC00847, MIR22HG and LNC_00027 were markedly increased in all treatment groups. It is of interest that LNC_00027 was identified as a novel lncRNA. Quantitative real-time PCR (qPCR) was employed to determine the differentially expressed lncRNA levels. Analysis using Gene Ontology (GO) enrichment identified the functions of target genes involved in systems development, metabolism, and protein binding. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that MC-LR exposure upregulated some important signaling pathways including pathway in cancer, PI3K-AKT signaling and MAPK pathway. In summary, data indicate that the MC-LR-induced alterations in lncRNA may be associated with hepatotoxicity and that upregulation of LINC00847, MIR22HG and LNC_00027 may play important roles in the observed MC-mediated liver damage.