Epigenetically regulated miR-449a enhances hepatitis B virus replication by targeting cAMP-responsive element binding protein 5 and modulating hepatocytes phenotype

Unraveling the Mechanisms of MicroRNA in Suppressing Hepatitis B Virus Progression: A Comprehensive Review for Designing Treatment Strategies

: Liver cancer and cirrhosis caused by the Hepatitis B virus (HBV) remain significant global health challenges due to the virus's high prevalence and contagious nature. Hepatitis B virus can be transmitted through various means, leading to mild or severe liver disease. Although an effective prophylactic vaccine is available, it offers limited benefits for those already chronically infected. Current treatments often fail to consistently eliminate the virus and can cause severe adverse effects. In response to these challenges, researchers have begun exploring microRNAs (miRNAs) as novel therapeutic targets. Studying miRNA-virus interactions presents a promising opportunity to identify potential therapeutic targets. By manipulating host miRNAs, researchers aim to enhance antiviral defenses, restore cellular balance, and prevent viral replication. The text concludes by highlighting the potential for personalized medicine in Hepatitis B treatment, guided by individual miRNA profiles. Numerous studies have been conducted to understand how different miRNAs inhibit HBV replication, paving the way for the development of innovative and effective therapeutic strategies.

MiRNA-449 family is epigenetically repressed and sensitizes to doxorubicin through ACSL4 downregulation in triple-negative breast cancer

Despite progress in breast cancer treatment, a significant portion of patients still relapse because of drug resistance. The involvement of microRNAs in cancer progression and chemotherapy response is well established. Therefore, this study aimed to elucidate the dysregulation of the microRNA-449 family (specifically, microRNA-449a, microRNA-449b-5p, and microRNA-449c-5p) and its impact on resistance to doxorubicin, a commonly used chemotherapeutic drug for the treatment of triple-negative breast cancer. We found that the microRNA-449 family is downregulated in triple-negative breast cancer and demonstrated its potential as a diagnostic biomarker. Besides, our findings indicate that the downregulation of the microRNA-449 family is mediated by the microRNAs-449/SIRT1-HDAC1 negative feedback loop. Moreover, it was found that the microRNA-449 family dysregulates the fatty acid metabolism by targeting ACSL4, which is a potential prognostic biomarker that mediates doxorubicin response through regulation of the drug extrusion pump ABCG2. Altogether, our results suggest that the microRNA-449 family might be a potential therapeutic target for the treatment of triple-negative breast cancer since it is implicated in doxorubicin response through ACSL4/ABCG2 axis regulation. Ultimately, our results also highlight the value of microRNAs-449 and ACSL4 as diagnostic and prognostic biomarkers in triple-negative breast cancer. Proposed model of miRNAs-449 downregulation in TNBC and doxorubicin response. MiRNAs-449 are downregulated in TNBC through a negative feedback loop with SIRT1 and HDAC1. Moreover, ACSL4 increases ABCG2 expression, thus diminishing the intracellular doxorubicin concentration and promoting doxorubicin resistance. MiRNAs-449 overexpression downregulates the ACSL4/ABCG2 axis and sensitizes doxorubicin-resistant cells to doxorubicin. Created with BioRender. TNBC: triple-negative breast cancer; DOX: doxorubicin; SIRT1: Sirtuin 1; HDAC1: Histone deacetylase 1; ACSL4: Acyl-CoA Synthetase Long-Chain Family Member 4; ABCG2: ATP-binding cassette superfamily G member 2.

RGS1 and CREB5 are direct and common transcriptional targets of ZNF384-fusion proteins

BACKGROUND

ZNF384-fusion (Z-fusion) genes were recently identified in B-cell acute lymphoblastic leukemia (B-ALL) and are frequent in Japanese adult patients. The frequency is about 20% in those with Philadelphia chromosome-negative B-ALL. ZNF384 is a transcription factor and Z-fusion proteins have increased transcriptional activity; however, the detailed mechanisms of leukemogenesis of Z-fusion proteins have yet to be clarified.

METHODS

We established three transfectants of cell lines expressing different types of Z-fusion proteins, and analyzed their gene expression profile (GEP) by RNA-seq. We also analyzed the GEP of clinical ALL samples using our previous RNA-seq data of 323 Japanese ALL patients. We selected upregulated genes in both Z-fusion gene-expressing transfectants and Z-fusion gene-positive ALL samples, and investigated the binding of Z-fusion proteins to regulatory regions of the candidate genes by ChIP-qPCR.

RESULTS

We selected six commonly upregulated genes. After the investigation by ChIP-qPCR, we finally identified CREB5 and RGS1 as direct and common target genes. RGS1 is an inhibitor of CXCL12-CXCR4 signaling that is required for the homing of hematopoietic progenitor cells to the bone marrow microenvironment and development of B cells. Consistent with this, Z-fusion gene transfectants showed impaired migration toward CXCL12.

CONCLUSIONS

We identified CREB5 and RGS1 as direct and common transcriptional targets of Z-fusion proteins. The present results provide novel insight into the aberrant transcriptional regulation by Z-fusion proteins.

MicroRNAs: Small molecules with big impacts in liver injury

A type of small noncoding RNAs known as microRNAs (miRNAs) fine-tune gene expression posttranscriptionally by binding to certain messenger RNA targets. Numerous physiological processes in the liver, such as differentiation, proliferation, and apoptosis, are regulated by miRNAs. Additionally, there is growing evidence that miRNAs contribute to liver pathology. Extracellular vesicles like exosomes, which contain secreted miRNAs, may facilitate paracrine and endocrine communication between various tissues by changing the gene expression and function of distal cells. The use of stable miRNAs as noninvasive biomarkers was made possible by the discovery of these molecules in body fluids. Circulating miRNAs reflect the conditions of the liver that are abnormal and may serve as new biomarkers for the early detection, prognosis, and evaluation of liver pathological states. miRNAs are appealing therapeutic targets for a range of liver disease states because altered miRNA expression is associated with deregulation of the liver's metabolism, liver damage, liver fibrosis, and tumor formation. This review provides a comprehensive review and update on miRNAs biogenesis pathways and mechanisms of miRNA-mediated gene silencing. It also outlines how miRNAs affect hepatic cell proliferation, death, and regeneration as well as hepatic detoxification. Additionally, it highlights the diverse functions that miRNAs play in the onset and progression of various liver diseases, including nonalcoholic fatty liver disease, alcoholic liver disease, fibrosis, hepatitis C virus infection, and hepatocellular carcinoma. Further, it summarizes the diverse liver-specific miRNAs, illustrating the potential merits and possible caveats of their utilization as noninvasive biomarkers and appealing therapeutic targets for liver illnesses.

A novel CREB5/TOP1MT axis confers cisplatin resistance through inhibiting mitochondrial apoptosis in head and neck squamous cell carcinoma

BACKGROUND

Cisplatin resistance is one of the main causes of treatment failure and death in head and neck squamous cell carcinoma (HNSCC). A more comprehensive understanding of the cisplatin resistance mechanism and the development of effective treatment strategies are urgent.

METHODS

RNA sequencing, RT-PCR, and immunoblotting were used to identify differentially expressed genes associated with cisplatin resistance. Gain- and loss-of-function experiments were performed to detect the effect of CREB5 on cisplatin resistance and mitochondrial apoptosis in HNSCC. Chromatin immunoprecipitation (ChIP) assay, dual-luciferase reporter assay, and immunoblotting experiments were performed to explore the underlying mechanisms of CREB5.

RESULTS

CREB5 was significantly upregulated in cisplatin-resistant HNSCC (CR-HNSCC) patients, which was correlated with poor prognosis. CREB5 overexpression strikingly facilitated the cisplatin resistance of HNSCC cells in vitro and in vivo, while CREB5 knockdown enhanced cisplatin sensitivity in CR-HNSCC cells. Interestingly, the activation of AKT signaling induced by cisplatin promoted nucleus translocation of CREB5 in CR-HNSCC cells. Furthermore, CREB5 transcriptionally activated TOP1MT expression depending on the canonical motif. Moreover, CREB5 silencing could trigger mitochondrial apoptosis and overcome cisplatin resistance in CR-HNSCC cells, which could be reversed by TOP1MT overexpression. Additionally, double-targeting of CREB5 and TOP1MT could combat cisplatin resistance of HNSCC in vivo.

CONCLUSIONS

Our findings reveal a novel CREB5/TOP1MT axis conferring cisplatin resistance in HNSCC, which provides a new basis to develop effective strategies for overcoming cisplatin resistance.

Silencing hepatitis B virus covalently closed circular DNA: The potential of an epigenetic therapy approach

Global prophylactic vaccination programmes have helped to curb new hepatitis B virus (HBV) infections. However, it is estimated that nearly 300 million people are chronically infected and have a high risk of developing hepatocellular carcinoma. As such, HBV remains a serious health priority and the development of novel curative therapeutics is urgently needed. Chronic HBV infection has been attributed to the persistence of the covalently closed circular DNA (cccDNA) which establishes itself as a minichromosome in the nucleus of hepatocytes. As the viral transcription intermediate, the cccDNA is responsible for producing new virions and perpetuating infection. HBV is dependent on various host factors for cccDNA formation and the minichromosome is amenable to epigenetic modifications. Two HBV proteins, X (HBx) and core (HBc) promote viral replication by modulating the cccDNA epigenome and regulating host cell responses. This includes viral and host gene expression, chromatin remodeling, DNA methylation, the antiviral immune response, apoptosis, and ubiquitination. Elimination of the cccDNA minichromosome would result in a sterilizing cure; however, this may be difficult to achieve. Epigenetic therapies could permanently silence the cccDNA minichromosome and promote a functional cure. This review explores the cccDNA epigenome, how host and viral factors influence transcription, and the recent epigenetic therapies and epigenome engineering approaches that have been described.

Gene signatures and potential therapeutic targets of Middle East respiratory syndrome coronavirus (MERS-CoV)-infected human lung adenocarcinoma epithelial cells

Background

Pathogenic coronaviruses include Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), and SARS-CoV-2. These viruses have induced outbreaks worldwide, and there are currently no effective medications against them. Therefore, there is an urgent need to develop potential drugs against coronaviruses.

Methods

High-throughput technology is widely used to explore differences in messenger (m)RNA and micro (mi)RNA expression profiles, especially to investigate protein–protein interactions and search for new therapeutic compounds. We integrated miRNA and mRNA expression profiles in MERS-CoV-infected cells and compared them to mock-infected controls from public databases.

Results

Through the bioinformatics analysis, there were 251 upregulated genes and eight highly differentiated miRNAs that overlapped in the two datasets. External validation verified that these genes had high expression in MERS-CoV-infected cells, including RC3H1, NF-κB, CD69, TNFAIP3, LEAP-2, DUSP10, CREB5, CXCL2, etc. We revealed that immune, olfactory or sensory system-related, and signal-transduction networks were discovered from upregulated mRNAs in MERS-CoV-infected cells. In total, 115 genes were predicted to be related to miRNAs, with the intersection of upregulated mRNAs and miRNA-targeting prediction genes such as TCF4, NR3C1, and POU2F2. Through the Connectivity Map (CMap) platform, we suggested potential compounds to use against MERS-CoV infection, including diethylcarbamazine, harpagoside, bumetanide, enalapril, and valproic acid.

Conclusions

The present study illustrates the crucial roles of miRNA-mRNA interacting networks in MERS-CoV-infected cells. The genes we identified are potential targets for treating MERS-CoV infection; however, these could possibly be extended to other coronavirus infections.

Cell death pathways and viruses: Role of microRNAs

Viral infections lead to the death of more than a million people each year around the world, both directly and indirectly. Viruses interfere with many cell functions, particularly critical pathways for cell death, by affecting various intracellular mediators. MicroRNAs (miRNAs) are a major example of these mediators because they are involved in many (if not most) cellular mechanisms. Virus-regulated miRNAs have been implicated in three cell death pathways, namely, apoptosis, autophagy, and anoikis. Several molecules (e.g., BECN1 and B cell lymphoma 2 [BCL2] family members) are involved in both apoptosis and autophagy, while activation of anoikis leads to cell death similar to apoptosis. These mechanistic similarities suggest that common regulators, including some miRNAs (e.g., miR-21 and miR-192), are involved in different cell death pathways. Because the balance between cell proliferation and cell death is pivotal to the homeostasis of the human body, miRNAs that regulate cell death pathways have drawn much attention from researchers. miR-21 is regulated by several viruses and can affect both apoptosis and anoikis via modulating various targets, such as PDCD4, PTEN, interleukin (IL)-12, Maspin, and Fas-L. miR-34 can be downregulated by viral infection and has different effects on apoptosis, depending on the type of virus and/or host cell. The present review summarizes the existing knowledge on virus-regulated miRNAs involved in the modulation of cell death pathways. Understanding the mechanisms for virus-mediated regulation of cell death pathways could provide valuable information to improve the diagnosis and treatment of many viral diseases.

Epigenetic modulation in chronic hepatitis B virus infection

The human hepatitis B virus (HBV) is a small-enveloped DNA virus causing acute and chronic hepatitis. Despite the existence of an effective prophylactic vaccine and the strong capacity of approved antiviral drugs to suppress viral replication, chronic HBV infection (CHB) continues to be a major health burden worldwide. Both the inability of the immune system to resolve CHB and the unique replication strategy employed by HBV, which forms a stable viral covalently closed circular DNA (cccDNA) minichromosome in the hepatocyte nucleus, enable infection persistence. Knowledge of the complex network of interactions that HBV engages with its host is still limited but accumulating evidence indicates that epigenetic modifications occurring both on the cccDNA and on the host genome in the course of infection are essential to modulate viral activity and likely contribute to pathogenesis and cancer development. Thus, a deeper understanding of epigenetic regulatory processes may open new venues to control and eventually cure CHB. This review summarizes major findings in HBV epigenetic research, focusing on the epigenetic mechanisms regulating cccDNA activity and the modifications determined in infected host cells and tumor liver tissues.

Circular RNA circVAPA knockdown suppresses colorectal cancer cell growth process by regulating miR-125a/CREB5 axis

Background

Colorectal cancer (CRC) is a malignant tumor, and the overall prognosis of patients with advanced CRC is still unsatisfactory. Circular RNAs (circRNAs) vesicle-associated membrane protein-associated protein A (circVAPA) could act as an underlying biomarker in CRC. This study aimed to explore the mechanism of circVAPA in the regulation of CRC growth.

Methods

CircVAPA level was measured in CRC tumor tissues. The expression levels of circVAPA, VAPA mRNA, microRNA-125a (miR-125a), and cAMP response element binding 5 (CREB5) in CRC cells were detected by RT-qPCR. Cell cycle progression, migration and invasion, extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were measured by flow cytometry, transwell assays and Seahorse XF96 Glycolysis Analyzer, severally. The levels of glucose uptake, lactate and ATP production were examined by Glucose Uptake Colorimetric Assay kit, Lactate Assay kit and ATP Colorimetric Assay kit, respectively. The interaction between miR-125a and circVAPA or CREB5 was predicted by Starbase or DIANA TOOL, and verified by the dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays.

Results

CircVAPA level was up-regulated in CRC tumor tissues. Expression levels of circVAPA and CREB5 were increased, and miR-125a was decreased in CRC cells. CircVAPA knockdown repressed CRC cells cycle progression, migration, invasion and glycolysis. CircVAPA acted as a miR-125a sponge to regulate CREB5 expression. Rescue assay confirmed that miR-125a deletion or CREB5 overexpression weakened the inhibitory effect of circVAPA knockdown on CRC growth.

Conclusion

Our studies disclosed that circVAPA knockdown suppressed CRC cells cycle progression, migration, invasion and glycolysis partly by modulating miR-125a/CREB5 axis, suggesting a potential therapeutic strategy for CRC treatment.

MicroRNA 876-5p modulates EV-A71 replication through downregulation of host antiviral factors

BACKGROUND

Human enterovirus 71 (EV-A71) is a non-enveloped virus that has a single stranded positive sense RNA genome. In a previous study, we showed that miR-876-5p upregulation was observed in the serum of patients with severe EV-A71 infection. Micro-876-5p (miR-876-5p) is a circulating miRNA that can be identified to modulate EV-A71 infections through both in vitro and in vivo studies. However, the regulatory mechanisms that involve miR-876-5p in the EV-A71 infection cycle remain unclear.

METHODS

We demonstrated that miR-876-5p facilitated EV-A71 replication and expression by overexpression and knocking-down of miR-876-5p through the transfection of miR-876-5p plasmid and miR-876-5p inhibitor. Although miR-876-5p suppressed CREB5 expression, luciferase reporter assay confirmed this. We also evaluated the role of miR-876-5p in the EV-A71 infection cycle by CREB5 mediated by transfection with an anti-miR-876-5P inhibitor or in combination with an si-CREB5 plasmid.

RESULTS

MicroR-876-5p was upregulated in EV-A71-infected neuroblastoma cells. Overexpression of miR-876-5p or knockdown of cyclic-AMP responsive element binding protein 5 (CREB5) promoted EV-A71 replication. The downregulation of miR-876-5p inhibited the accumulation of viral RNA and the production of viral proteins. Interestingly, CREB5 overexpression also suppressed EV-A71 replication. Our in vitro studies reveal that miR-876-5p directly targets CREB5. Finally, downregulation of CREB5 protein abated the inhibitory effect of anti-miR-876-5p and induced inhibitory effect of EV-A71 replication.

CONCLUSIONS

Our results suggest that intracellular miR-876-5p promotes EV-A71 replication indirectly by targeting the host CREB5 protein.

The microRNA-155 mediates hepatitis B virus replication by reinforcing SOCS1 signalling-induced autophagy

As small conserved RNAs without a coding function, microRNAs are expressed in multicellular organisms and contribute to the modulation of multiple cellular reactions, such as viral replication, as well as autophagy. microRNAs can regulate host gene expression and inhibit or reinforce hepatitis B virus (HBV) replication. Hepatic cells express miR-155 noticeably. Consequently, our study explored miR-155 modulation of HBV replication and investigated the potential mechanism involved. miR-155 was inhibited on HBV infection. miR-155 transfection remarkably reinforced HBV replication, antigen expression, and progeny secretion in HepG2215 cells. Moreover, miR-155 impaired the inhibition of the cytokine signalling 1 (SOCS1)/Akt/mTOR axis and reinforced HepG2215 autophagy. Additionally, the autophagy inhibitor (3-MA) eliminated HBsAg secretion triggered by miR-155. Taken together, miR-155 reinforced HBV replication by reinforcing SOCS1-triggered autophagy. SIGNIFICANCE OF THE STUDY: The research studied the potential mechanism involved in HBV replication and miR-155 that miR-155 reinforces HBV replication by reinforcing the SOCS1/Akt/mTOR axis-stimulated autophagy, and therefore, it can provide medical practitioners with the inspiration that chronic HBV might be cured or improved by regulating the activation of miR-155 in cells. In the study, the experiments show that autophagy inhibitors (3-MA) counteracted miR-155 contribution to HBV replication, and it might be a practicable way to improve HBV through some therapies that can repress the autophagy in related cells.

MicroRNA-325-3p inhibits cell proliferation and induces apoptosis in hepatitis B virus-related hepatocellular carcinoma by down-regulation of aquaporin 5

BACKGROUND

Hepatitis B virus (HBV) infection is acknowledged as the main cause of hepatocellular carcinoma (HCC). Moreover, previous studies have revealed that microRNAs (miRNAs) widely participate in regulation of various cellular processes, such as viral replication. Hence, the purpose of this study was to investigate the roles of aquaporin 5 (AQP5) and miR-325-3p in the proliferation and apoptosis of HBV-related HCC cells.

METHODS

AQP5 and miR-325-3p expression in both normal and HBV-HCC tissues or cells (both Huh7-1.3 and HepG2.2.15) was detected using qRT-PCR. AQP5 expression was knocked down in HBV-related Huh7-1.3 and HepG2.2.15 cells using small interfering RNA (siRNA) technology. Down-regulation was confirmed using real-time PCR and Western blot analysis. Effects of AQP5 down-regulation on the proliferation and apoptosis were assessed. Dual luciferase reporter gene assay, Western blot and qRT-PCR were employed to evaluate the effect of miR-325-3p on the luciferase activity and expression of AQP5. Moreover, miR-325-3p mimic-induced changes in cellular proliferation and apoptosis were detected through CCK-8 assay, BrdU assay, flow cytometry analysis and ELISA.

RESULTS

In this study, the expression of AQP5 was up-regulated in human HBV-HCC tissue, Huh7-1.3 and HepG2.2.15 cells. Knockdown of AQP5 significantly inhibited the proliferation and promoted apoptosis of HBV-HCC cells. Next, miR-325-3p was obviously down-regulated in HBV-HCC. In concordance with this, MiR-325-3p directly targeted AQP5, and reduced both mRNA and protein levels of AQP5, which promoted cell proliferation and suppressed cell apoptosis in HCC cells. Overexpression of miR-325-3p dramatically inhibited cell proliferation and induced cell apoptosis.

CONCLUSIONS

Our findings clearly demonstrated that introduction of miR-325-3p inhibited proliferation and induced apoptosis of Huh7-1.3 and HepG2.2.15 cells by directly decreasing AQP5 expression, and that silencing AQP5 expression was essential for the pro-apoptotic effect of miR-325-3p overexpression on Huh7-1.3 and HepG2.2.15 cells. It is beneficial to gain insight into the mechanism of HBV infection and pathophysiology of HBV-related HCC.

Variations in maternal adenylate cyclase genes are associated with congenital Zika syndrome in a cohort from Northeast, Brazil

BACKGROUND

Vertical transmission of Zika virus (ZIKV) is associated with congenital malformations but the mechanism of pathogenesis remains unclear. Although host genetics appear to play a role, no genetic association study has yet been performed to evaluate this question. In order to investigate if maternal genetic variation is associated with Congenital Zika Syndrome (CZS), we conducted a case-control study in a cohort of Brazilian women infected with ZIKV during pregnancy.

METHODS

A total of 100 women who reported symptoms of zika during pregnancy were enrolled and tested for ZIKV. Among 52 women positive for ZIKV infection, 28 were classified as cases and 24 as controls based on the presence or absence of CZS in their infants. Variations in the coding region of 205 candidate genes involved in cAMP signaling or immune response were assessed by high throughput sequencing and tested for association with development of CZS.

RESULTS

From the 817 single nucleotide variations (SNVs) included in association analyses, 22 SNVs in 17 genes were associated with CZS under an additive model (alpha = 0.05). Variations c.319T>C (rs11676272) and c.1297G>A, located at ADCY3 and ADCY7 genes showed the most prominent effect. The association of ADCY3 and ADCY7 genes was confirmed using a Sequence Kernel Association Test to assess the joint effect of common and rare variations, and results were statistically significant after adjustment for multiple comparisons (P < 0.002).

CONCLUSION

These results suggest that maternal ADCY genes contribute to ZIKV pathogenicity and influence the outcome of CZS, being promising candidates for further replication studies and functional analysis.

MicroRNA-34/449 family and viral infections

MicroRNAs are short, endogenous, nonprotein-coding RNAs that are essential for regulation of cellular processes through gene silencing. The miR-34/449 family is conserved in mammalian organisms and generally comprises six homologous genes: miR-34a, miR-34b, miR-34c, miR-449a, miR-449b and miR-449c, at three genomic loci. Strong similarity in the sequence of these miRNAs, particularly at the seed region, predicts robust functional redundancy. A large proportion of the literature on the miR-34/449 family focuses on its role in regulating cell cycle arrest and apoptosis by modulating E2F- and p53-related signaling pathways. A growing subset of the literature reports that the miR-34/449 family is involved in the regulation of immune responses and viral infections, and data suggest the potential for miR-34/446 as a diagnostic and therapeutic target. In this review, we discuss our current understanding of the conservation and transcriptional regulation of the miR-34/449 family and review the literature on its functions in viral infections.

LncRNA SNHG5 affects cell proliferation, metastasis and migration of colorectal cancer through regulating miR-132-3p/CREB5

We aimed at the effects of long non-coding RNA (lncRNA) SNHG5 on proliferation, metastasis and migration of colorectal cancer (CRC) cells. We also investigated regulatory relationships among miR-132-3p, SNHG5 and CREB5 and their roles in CRC. 25 pairs of samples containing CRC tissues and matched para-tumor tissues were obtained to examine SNHG5, miR-132-3p and CREB5 expression by qRT-PCR or Western blot. The targeted relationship between miR-132-3p and SNHG5 or CREB5 was confirmed by dual luciferase report assay as well as RNA pull down assay. The expression of SNHG5, miR-132-3p and CREB5 in CRC cells were regulated by cell transfection. CRC cellular proliferation was assayed by CCK-8 and meanwhile flow cytometry was adopted to observe apoptosis. Metastasis and migration of CRC cells were determined respectively by means of Transwell assay and scratch test. The effects of SNHG5 on CRC were researched in vivo, too. SNHG5 or CREB5 was up-regulated in CRC tissues and cells, whereas miR-132-3p was down-regulated. Overexpression of SNHG5 and CREB5 resulted in the enhancement of proliferation, metastasis, migration and the inhibition of apoptosis in CRC cells, while miR-132-3p led to the opposite result. LncRNA SNHG5 promoted proliferation, migration and metastasis of CRC cells but inhibited apoptosis by modulating miR-132-3p/CERB5.

Clinical significance of microRNA-449a in hepatocellular carcinoma with microarray data mining together with initial bioinformatics analysis

Increasing evidence has demonstrated that microRNA (miR)-449a expression is reduced in various types of tumors and that it serves as a tumor suppressor. However, the molecular mechanism of miR-449a in hepatocellular carcinoma (HCC) has not been thoroughly elucidated and is disputed. Therefore, the aim of the present work was to systematically review the current literature and to utilize the public Gene Expression Omnibus database to determine the role of miR-449a and its significance in HCC. A total of eight original papers and seven microarrays were included in the present study. Based on the evidence, miR-449a was reduced in HCC. miR-449a is likely involved in various signaling pathways and is targeted to multiple mRNA as part of its function in HCC. In addition, a preliminary bioinformatic analysis was conducted for miR-449a to investigate the novel potential pathways that miR-449a may participate in regarding HCC.

Epigenetics and MicroRNAs in Cancer

The ability to reprogram the transcriptional circuitry by remodeling the three-dimensional structure of the genome is exploited by cancer cells to promote tumorigenesis. This reprogramming occurs because of hereditable chromatin chemical modifications and the consequent formation of RNA-protein-DNA complexes that represent the principal actors of the epigenetic phenomena. In this regard, the deregulation of a transcribed non-coding RNA may be both cause and consequence of a cancer-related epigenetic alteration. This review summarizes recent findings that implicate microRNAs in the aberrant epigenetic regulation of cancer cells.

miR-224 suppresses HBV replication posttranscriptionally through inhibiting SIRT1-mediated autophagy

Hepatitis B virus (HBV) enters the host and successfully completes replication by using several mechanisms, including autophagy. However, previous studies revealed that microRNAs (miRNAs) widely participate in regulation of various cellular processes, such as autophagy and viral replication. Hence, the purpose of this study was to investigate the role of miR-224 in HBV infection and to determine whether its role depended on the miR-224/SIRT1/autophagy axis. Our results show that secretions of HBeAg and HBsAg, and HBV replication significantly declined in Huh7-1.3 cells, established by transfecting recombinant pcDNA 3.0-1.3 mer containing the 1.3 mer fragment of HBV genomic DNA,with miR-224 mimic transfection as compared to the Huh7-1.3 group. Moreover, it was discovered that HBV could induce autophagy, while miR-224 inhibited autophagy caused by HBV. Additionally, miR-224 could suppress SIRT1, LC3 expression, and facilitate p62 expression. SIRT1 was identified as the target gene of miR-224 and down-regulation of SIRT1 via miR-224 or si-SIRT1 transfected treatment in Huh7-1.3 cells repressed LC3 expression and enhanced p62 expression. In conclusion, these results suggest that miR-224 might hinder HBV replication through attenuating SIRT1-mediated autophagy, thereby these findings open a new avenue for the treatment of HBV infection.

A transcriptomic study of myogenic differentiation under the overexpression of PPARγ by RNA-Seq

To study the cellular and molecular function of peroxisome proliferator-activated receptor γ (PPARγ) in skeletal muscle differentiation, we have generated inducible gain-of-function to overexpress PPARγ in C2C12 myoblasts. In order to identify PPARγ targets, RNA sequencing (RNA-seq) was used to evaluate and quantify the transcriptomes and expression patterns during myogenic differentiation under the overexpression of PPARγ. The formation of myotubes and the expression of muscle-specific myogenic genes such as MyoD and MyoG may be inhibited by PPARγ overexpression. Multiple genes and pathways were significantly involved in this process, including 11 genes such as Fndc9 and Slc14a1 with fundamental change of regulation modes, 9 genes of which were validated by the data of qRT-PCR. Our studies demonstrate that PPARγ would play critical roles on myoblasts differentiation, mediating crosstalk among several pathways and transcription factors. Our data is available in the Gene Expression Omnibus (GEO) database with the accession number as GSE99399.

CREB5 promotes tumor cell invasion and correlates with poor prognosis in epithelial ovarian cancer

CAMP responsive element binding protein 5 (CREB5) has crucial roles in regulating cell growth, proliferation, differentiation and cell cycle regulation. CREB5 has been identified to be overexpressed in several types of human cancer. However, the expression characteristics of CREB5 in epithelial ovarian cancer remains unknown, and its potential clinical prognostic significance has not yet been elucidated. In the present study, quantitative polymerase chain reaction (qPCR) and western blot analysis were performed to detect CREB5 mRNA and protein expression levels in 10 fresh tissue and cell lines epithelial ovarian cancer. Furthermore, CREB5 expression was analyzed using immunohistochemical analysis in 125 clinicopathologically characterized ovarian cancers: Stage I+II (n=31), stage III (n=70), stage IV (n=24). The patient survival rate was evaluated using Kaplan-Meier analysis. CREB5 was significantly overexpressed at both the mRNA and protein levels in epithelial ovarian cancer cells. There was a significant positive correlation between high CREB5 expression and increasing the International Federation of Gynecology and Obstetrics (FIGO) stage and pelvic lymph node metastasis (P<0.05). Patients with high CREB5 expression had a shorter overall survival, whereas patients with low CREB5 expression had longer survival. In addition, patients with high CREB5 expression had shorter relapse-free survival whereas patients with low CREB5 expression had longer relapse-free survival. Univariate logistic regression analysis and stepwise multivariate analysis all revealed that the FIGO stage and high CREB5 expression were significant risk factors for epithelial ovarian cancer (P<0.001), which suggested that CREB5 upregulation may be associated with a poor prognosis; therefore, it may be an independent prognostic indicator of epithelial ovarian cancer and may serve as a tumor-aggressive gene.

miR-29a promotes hepatitis B virus replication and expression by targeting SMARCE1 in hepatoma carcinoma

AIM

To investigate the functional role and underlying molecular mechanism of miR-29a in hepatitis B virus (HBV) expression and replication.

METHODS

The levels of miR-29a and SMARCE1 in HBV-infected HepG2.2.15 cells were measured by quantitative real-time PCR and western blot analysis. HBV DNA replication was measured by quantitative PCR and Southern blot analysis. The relative levels of hepatitis B surface antigen and hepatitis B e antigen were detected by enzyme-linked immunosorbent assay. The Cell Counting Kit-8 (CCK-8) was used to detect the viability of HepG2.2.15 cells. The relationship between miR-29a and SMARCE1 were identified by target prediction and luciferase reporter analysis.

RESULTS

miR-29a promoted HBV replication and expression, while SMARCE1 repressed HBV replication and expression. Cell viability detection indicated that miR-29a transfection had no adverse effect on the host cells. Moreover, SMARCE1 was identified and validated to be a functional target of miR-29a. Furthermore, restored expression of SMARCE1 could relieve the increased HBV replication and expression caused by miR-29a overexpression.

CONCLUSION

miR-29a promotes HBV replication and expression through regulating SMARCE1. As a potential regulator of HBV replication and expression, miR-29a could be a promising therapeutic target for patients with HBV infection.

MicroRNA-125b-5p mediates post-transcriptional regulation of hepatitis B virus replication via the LIN28B/let-7 axis

MicroRNAs (miRNAs) are able to modulate hepatitis B virus (HBV) replication and play an important role in the pathogenesis of HBV infection. Recently, we have identified that serum miR-125b-5p levels correlated with HBV DNA levels and liver necroinflammation. In the present study, we addressed how miR-125b-5p regulated HBV replication at the different steps, inclduing viral transcription, assembly, and virion production and investigated the underlying mechanisms. We found that miR-125b-5p overexpression increased HBV replication without altering HBV transcription. This is the first demonstration of post-transcriptional miRNA regulation of HBV replication. In contrast, transfection of miR-125b-5p inhibitor resulted in downregulation of HBV replication in hepatoma cells. Further, miR-125b-5p inhibited the phosphorylation of retinoblastoma protein and blocked cell cycle progression at the G1/S phase in hepatoma cell lines. Our results indicate that certain miRNAs are able to arrest the cell cycle at G1 phase and may increase HBV replication. RNA sequencing revealed several liver-specific metabolic pathways regulated by miR-125b-5p, which was also found to suppress LIN28B and induce let-7 family members. Additional data demonstrated that miR-125b-5p targeted the LIN28B/let-7 axis to stimulate HBV replication at a post-transcriptional step.

MITA/STING and Its Alternative Splicing Isoform MRP Restrict Hepatitis B Virus Replication

An efficient clearance of hepatitis B virus (HBV) requires the coordinated work of both the innate and adaptive immune responses. MITA/STING, an adapter protein of the innate immune signaling pathways, plays a key role in regulating innate and adaptive immune responses to DNA virus infection. Previously, we identified an alternatively spliced isoform of MITA/STING, called MITA-related protein (MRP), and found that MRP could specifically block MITA-mediated interferon (IFN) induction while retaining the ability to activate NF-κB. Here, we asked whether MITA/STING and MRP were able to control the HBV replication. Both MITA/STING and MRP significantly inhibited HBV replication in vitro. MITA overexpression stimulated IRF3-IFN pathway; while MRP overexpression activated NF-κB pathway, suggesting these two isoforms may inhibit HBV replication through different ways. Using a hydrodynamic injection (HI) mouse model, we found that HBV replication was reduced following MITA/STING and MRP expression vectors in mice and was enhanced by the knockout of MITA/STING (MITA/STING^-/-). The HBV specific humoral and CD8⁺ T cell responses were impaired in MITA/STING deficient mice, suggesting the participation of MITA/STING in the initiation of host adaptive immune responses. In summary, our data suggest that MITA/STING and MRP contribute to HBV control via modulation of the innate and adaptive responses.

The microRNA-99 family modulates hepatitis B virus replication by promoting IGF-1R/PI3K/Akt/mTOR/ULK1 signaling-induced autophagy

MicroRNAs are small highly conserved noncoding RNAs that are widely expressed in multicellular organisms and participate in the regulation of various cellular processes including autophagy and viral replication. Evidently, microRNAs are able to modulate host gene expression and thereby inhibit or enhance hepatitis B virus (HBV) replication. The miR-99 family members are highly expressed in the liver. Interestingly, the plasma levels of miR-99 family in the peripheral blood correspond with HBV DNA loads. Thus, we asked whether the miR-99 family regulated HBV replication and analyzed the underlying molecular mechanism. Compared with primary hepatocytes, miR-99 family expression was downregulated in hepatoma cells. Transfection of miR-99a, miR-99b, and miR-100 markedly increased HBV replication, progeny secretion, and antigen expression in hepatoma cells. However, miR-99 family had no effect on HBV transcription and HBV promoter activities, suggesting that they regulate HBV replication at posttranscriptional steps. Consistent with bioinformatic analysis and recent reports, ectopic expression of miR-99 family attenuated IGF-1R/Akt/mTOR pathway signaling and repressed insulin-stimulated activation in hepatoma cells. Moreover, the experimental data demonstrated that the miR-99 family promoted autophagy through mTOR/ULK1 signaling and thereby enhanced HBV replication. In conclusion, the miR-99 family promotes HBV replication posttranscriptionally through IGF-1R/PI3K/Akt/mTOR/ULK1 signaling-induced autophagy.

The role of microRNAs in hepatocyte metabolism and hepatitis B virus replication

Though efficient vaccines against hepatitis B virus (HBV) and antiviral therapies are available, chronic HBV infection is still a global health problem. The process of HBV infection and HBV life cycle are extensively studied in last decades, however, the mechanisms of HBV-induced alterations of host cell metabolisms and host factors involved in modulating of viral replication are not fully understood. Thus, it is an important issue to examine these specific HBV-host interactions for development of novel strategies for antiviral therapies. Recently, microRNAs (miRNAs), a class of post-transcriptional regulatory small RNA, seem to be the relevant fine tuning factors of various cellular activities and pathways, including cell growth, metabolism, and viral replication. In this review, we summarize the up to date knowledge concerning the virus-host interactions and emphasizing on the role of miRNAs in regulation of HBV replication and host cell metabolism.