Repression of MicroRNA Function Mediates Inflammation-associated Colon Tumorigenesis

CA19-9-Positive Extracellular Vesicle Is a Risk Factor for Cancer-Associated Thrombosis in Pancreatic Cancer

BACKGROUND AND AIMS

Cancer-associated venous thromboembolism (VTE) is a frequent complication associated with high mortality in patients with cancer, particularly pancreatic cancer. While biological factors such as coagulation factors released from cancer cells may underlie the mechanisms of cancer-associated VTE, the detailed mechanisms have not been determined. Here, we aimed to determine whether extracellular vesicles carrying a glycan sialyl-Lewisa, known as carbohydrate antigen 19-9 (CA19-9), which is a clinically used serum tumor marker and selectin ligand, are a significant cause of cancer-associated VTE.

METHODS

Risk factors for cancer-associated VTE were determined using clinical data. EVs derived from CA19-9-deficient or overexpressing pancreatic cancer cells were characterized. The protein levels of coagulation factors on the surface of the EVs were quantified using our newly developed sensitive method.

RESULTS

Higher CA19-9 levels in the sera of patients were significantly associated with the occurrence of VTE. Using CA19-9-negative or overexpressing pancreatic cancer cells, we found that EVs derived from these cells interacted with E-selectin of endothelial cells in a CA19-9-dependent manner in cell-based assays and in vitro blood vessel models. EVs derived from cancer cells have higher tissue factor levels on their surfaces, and increased tissue factor activity is induced locally, where CA19-9-positive EVs bind to activated endothelial cells.

CONCLUSION

These results suggest that the binding between CA19-9-positive EVs released from cancer cells and endothelial cell E-selectin explains the increased frequency of VTE in patients with pancreatic cancer.

KRT6A expedites bladder cancer progression, regulated by miR-31-5p

Bladder cancer is one of the most severe life-threatening illnesses worldwide. To contribute to a solution to this public health issue, here, we sought to identify a novel biomarker for the early diagnosis of bladder tumors. We conducted RNA sequence analysis utilizing samples from tumorous tissue and adjacent healthy tissue in bladder cancer patients and found that KRT6A was upregulated in bladder tumor tissues, suggesting that it might be a candidate for involvement in bladder tumorigenesis. Accordingly, we performed a series of experiments to further verify the role of KRT6A in bladder tumor progression. Our results revealed that KRT6A promoted bladder tumor cell viability, proliferation, and adhesion, while diminishing bladder tumor cell apoptosis. We also focused on the role of epigenetics in bladder tumors and verified that KRT6A was a miR-31-5p target gene, and its positive effect on bladder tumor progression was relieved by miR-31-5p. Overall, this study sheds new light regarding a novel oncogenic regulatory axis, KRT6A/miR-31-5p, which is related to bladder tumor growth.

Mutant KRAS drives metabolic reprogramming and autophagic flux in premalignant pancreatic cells

Mutational activation of the KRAS gene occurs in almost all pancreatic ductal adenocarcinoma (PDAC) and is the earliest molecular event in their carcinogenesis. Evidence has accumulated of the metabolic reprogramming in PDAC, such as amino acid homeostasis and autophagic flux. However, the biological effects of KRAS mutation on metabolic reprogramming at the earlier stages of PDAC carcinogenesis are unclear. Here we report dynamic metabolic reprogramming in immortalized human non-cancerous pancreatic ductal epithelial cells, in which a KRAS mutation was induced by gene-editing, which may mimic early pancreatic carcinogenesis. Similar to the cases of PDAC, KRAS gene mutation increased the dependency on glucose and glutamine for maintaining the intracellular redox balance. In addition, the intracellular levels of amino acids were significantly decreased because of active protein synthesis, and the cells required greater autophagic flux to maintain their viability. The lysosomal inhibitor chloroquine significantly inhibited cell proliferation. Therefore, metabolic reprogramming is an early event in carcinogenesis initiated by KRAS gene mutation, suggesting a rationale for the development of nutritional interventions that suppress or delay the development of PDAC.

MiR-126 downregulates CXCL12 expression in intestinal epithelial cells to suppress the recruitment and function of macrophages and tumorigenesis in a murine model of colitis-associated colorectal cancer

Inflammatory bowel disease, characterised by chronic relapsing‐remitting colitis, is a significant risk factor for colorectal cancer (CRC). Previously, we showed that miR‐126 functions as a tumour suppressor in CRC and is inversely correlated with tumour proliferation, metastasis and patient prognosis. In the current study, we documented a protective role for miR‐126 in colitis‐associated CRC (CAC) and its underlying mechanism. We detected downregulated miR‐126 expression during colorectal tumorigenesis in the mouse CAC model and in specimens from patients with CRC. The deficiency of miR‐126 in intestinal epithelial cells (IECs) exacerbated tumorigenesis in mice. We identified CXCL12 as a direct target of miR‐126 in inhibiting the development of colitis and CAC. Moreover, miR‐126 regulated the recruitment of macrophages via CXCL12 and decreased the levels of proinflammatory cytokines (IL‐6, IL‐12 and IL‐23). In addition, IL‐6 secreted by macrophages, which were regulated by cocultured transfected CRC cells, altered the proliferation and migration of colon cells. Our data suggest that miR‐126 exerts an antitumour effect on CAC by regulating the crosstalk between IECs and macrophages via CXCL12‐IL‐6 signalling. Our study contributes to the understanding of cancer progression and suggests miR‐126 as a potential therapy for CRC.

Exploring Immune-Related Prognostic Signatures in the Tumor Microenvironment of Colon Cancer

Background: Colon cancer is a common malignant tumor with poor prognosis. The aim of this study is to explore the immune-related prognostic signatures and the tumor immune microenvironment of colon cancer.

Methods: The mRNA expression data of TCGA-COAD from the UCSC Xena platform and the list of immune-related genes (IRGs) from the ImmPort database were used to identify immune-related differentially expressed genes (DEGs). Then, we constructed an immune-related risk score prognostic model and validated its predictive performance in the test dataset, the whole dataset, and two independent GEO datasets. In addition, we explored the differences in tumor-infiltrating immune cell types, tumor mutation burden (TMB), microsatellite status, and expression levels of immune checkpoints and their ligands between the high-risk and low-risk score groups. Moreover, the potential value of the identified immune-related signature with respect to immunotherapy was investigated based on an immunotherapeutic cohort (Imvigor210) treated with an anti-PD-L1 agent.

Results: Seven immune-related DEGs were identified as prognostic signatures. The areas under the curves (AUCs) of the constructed risk score model for overall survival (OS) were calculated (training dataset: 0.780 at 3 years, 0.801 at 4 years, and 0.766 at 5 years; test dataset: 0.642 at 3 years, 0.647 at 4 years, and 0.629 at 5 years; and the whole dataset: 0.642 at 3 years, 0.647 at 4 years, and 0.629 at 5 years). In the high-risk score group of the whole dataset, patients had worse OS, higher TMN stages, advanced pathological stages, and a higher TP53 mutation rate (p < 0.05). In addition, a high level of resting NK cells or M0 macrophages, and high TMB were significantly related to poor OS (p < 0.05). Also, we observed that high-risk score patients had a high expression level of PD-L1, PD-1, and CTLA-4 (p < 0.05). The patients with high-risk scores demonstrated worse prognosis than those with low-risk scores in multiple datasets (GSE39582: p = 0.0023; GSE17536: p = 0.0008; immunotherapeutic cohort without platinum treatment: p = 0.0014; immunotherapeutic cohort with platinum treatment: p = 0.0027).

Conclusion: We developed a robust immune-related prognostic signature that performed great in multiple cohorts and explored the characteristics of the tumor immune microenvironment of colon cancer patients, which may give suggestions for the prognosis and immunotherapy in the future.

miR-671-5p Inhibition by MSI1 Promotes Glioblastoma Tumorigenesis via Radioresistance, Tumor Motility and Cancer Stem-like Cell Properties

MicroRNAs (miRNAs) could be potential biomarkers for glioblastoma multiforme (GBM) prognosis and response to therapeutic agents. We previously demonstrated that the cancer stem cell marker Musashi-1 (MSI1) is an RNA binding protein that promotes radioresistance by increasing downstream RNA stability. To identify that MSI1 interacts with miRNAs and attenuates their function, we also get candidate miRNAs from the mRNA seq by predicting with TargetScan software. miR-671-5p in GBM cells interacts with MSI1 by intersecting the precipitated miRNAs with the predicted miRNAs. Notably, overexpression of MSI1 reversed the inhibitory effect of miR-671-5p. The phenotype of miR-671-5p in GBM cells could affect radiosensitivity by modulating the posttranscriptional activity of STAT3. In addition, miR-671-5p could attenuate tumor migration and cancer stem cell (CSC) characteristics by repressing the posttranscriptional activity of TRAF2. MSI1 may regulate GBM radioresistance, CSCs and tumor motility through miR-671-5p inhibition to increasing STAT3 and TRAF2 presentation. In vivo, the GBM tumor size was inversely correlated with miR-671-5p expression, but tumorigenesis was promoted by STAT3 and TRAF2 activation in the miR-671-5p-positive GBM population. miR-671-5p could be activated as a novel therapeutic target for GBM and has potential application as a predictive biomarker of glioblastoma prognosis.

IL-1α and colorectal cancer pathogenesis: Enthralling candidate for anti-cancer therapy

Inflammation has been well-established as a hallmark of colorectal cancer (CRC). Interleukin-1 alpha (IL-1α) is one of the primary inflammatory mediators driving the pathogenesis of inflammation-associated CRC. This systematic review presents the roles of IL-1α in the pathogenesis of the disease. Bibliographic databases PubMed, Science Direct, Scopus and Web of Science were systematically searched for articles that addresses the relationship between IL-1α and colorectal cancer. We highlighted various mechanisms by which IL-1α promotes the pathogenesis of CRC including enhancement of angiogenesis, metastasis, resistance to therapy, and inhibition of tumour suppressive genes. We also discussed the potential mechanisms by which IL-1α expression is induced or secreted in various studies. Beyond these, the systematic review also highlights several potential therapeutic strategies which should be further explored in the future; to target IL-1α and/or its associated pathways; paving our way in finding effective treatments for CRC patients.

Preclinical Development of FA5, a Novel AMP-Activated Protein Kinase (AMPK) Activator as an Innovative Drug for the Management of Bowel Inflammation

Acadesine (ACA), a pharmacological activator of AMP-activated protein kinase (AMPK), showed a promising beneficial effect in a mouse model of colitis, indicating this drug as an alternative tool to manage IBDs. However, ACA displays some pharmacodynamic limitations precluding its therapeutical applications. Our study was aimed at evaluating the in vitro and in vivo effects of FA-5 (a novel direct AMPK activator synthesized in our laboratories) in an experimental model of colitis in rats. A set of experiments evaluated the ability of FA5 to activate AMPK and to compare the efficacy of FA5 with ACA in an experimental model of colitis. The effects of FA-5, ACA, or dexamethasone were tested in rats with 2,4-dinitrobenzenesulfonic acid (DNBS)-induced colitis to assess systemic and tissue inflammatory parameters. In in vitro experiments, FA5 induced phosphorylation, and thus the activation, of AMPK, contextually to the activation of SIRT-1. In vivo, FA5 counteracted the increase in spleen weight, improved the colon length, ameliorated macroscopic damage score, and reduced TNF and MDA tissue levels in DNBS-treated rats. Of note, FA-5 displayed an increased anti-inflammatory efficacy as compared with ACA. The novel AMPK activator FA-5 displays an improved anti-inflammatory efficacy representing a promising pharmacological tool against bowel inflammation.

Cardamonin Attenuates Experimental Colitis and Associated Colorectal Cancer

Cardamonin is a naturally occurring chalcone, majorly from the Zingiberaceae family, which includes a wide range of spices from India. Herein, we investigated the anti-inflammatory property of cardamonin using different in vitro and in vivo systems. In RAW 264.7 cells, treatment with cardamonin showed a reduced nitrous oxide production without affecting the cell viability and decreased the expression of iNOS, TNF-α, and IL-6, and inhibited NF-kB signaling which emphasizes the role of cardamonin as an anti-inflammatory molecule. In a mouse model of dextran sodium sulfate (DSS)-induced colitis, cardamonin treatment protected the mice from colitis. Subsequently, we evaluated the therapeutic potential of this chalcone in a colitis-associated colon cancer model. We performed microRNA profiling in the different groups and observed that cardamonin modulates miRNA expression, thereby inhibiting tumor formation. Together, our findings indicate that cardamonin has the potential to be considered for future therapy against colorectal cancer.

Assessment of plasma microRNAs in congenital intestinal malrotation

Intestinal malrotation in newborns often requires urgent surgical treatment, especially in the presence of volvulus. Therefore, early-stage diagnosis is critical. In the present study, differentially expressed plasma microRNAs (miRNAs) were screened for in patients with intestinal malrotation using high-throughput Illumina sequencing, and validated using reverse transcription-quantitative PCR. Receiver operating characteristic curve (ROC) analysis was conducted to evaluate their specificity, sensitivity and assess their diagnostic value for intestinal malrotation. Bioinformatics analysis was performed to investigate the functions associated with the dysregulated miRNAs. A profile consisting of 28 differentially expressed plasma miRNAs was obtained, of which nine were verified to exhibit significantly altered expression. According to a ROC analysis, four of these could represent novel early-stage, non-invasive biomarkers for intestinal malrotation. Bioinformatics analysis demonstrated that the differentially expressed miRNAs were predominantly involved in ‘metal ion transmembrane transporter activity’ and ‘calcium-dependent protein binding’, which may be related to the ‘endocytosis’ pathway. In conclusion, significantly differentially expressed plasma miRNAs were identified in congenital intestinal malrotation and their potential roles were described. These differentially expressed miRNAs may serve as biomarkers of intestinal malrotation and improve early diagnosis for this condition.

Rescuing Dicer expression in inflamed colon tissues alleviates colitis and prevents colitis-associated tumorigenesis

Chronic inflammation is known to promote carcinogenesis; Dicer heterozygous mice are more likely to develop colitis-associated tumors. This study investigates whether Dicer is downregulated in inflamed colon tissues before malignancy occurs and whether increasing Dicer expression in inflamed colon tissues can alleviate colitis and prevent colitis-associated tumorigenesis. Methods: Gene expression in colon tissues was analyzed by immunohistochemistry, immunoblots, and real-time RT-PCR. Hydrogen peroxide or N-acetyl-L-cysteine was used to induce or alleviate oxidative stress, respectively. Mice were given azoxymethane followed by dextran sulfate sodium to induce colitis and colon tumors. Berberine, anastrozole, or pranoprofen was used to rescue Dicer expression in inflammatory colon tissues. Results: Oxidative stress repressed Dicer expression in inflamed colon tissues by inducing miR-215 expression. Decreased Dicer expression increased DNA damage and cytosolic DNA and promoted interleukin-6 expression upon hydrogen peroxide treatment. Dicer overexpression in inflamed colon tissues alleviated inflammation and repressed colitis-associated carcinogenesis. Furthermore, we found that anastrozole, berberine, and pranoprofen could promote Dicer expression and protect cells from hydrogen peroxide-induced DNA damage, thereby reducing cytosolic DNA and partially repressing interleukin-6 expression upon hydrogen peroxide treatment. Rescuing Dicer expression using anastrozole, berberine, or pranoprofen in inflamed colon tissues alleviated colitis and prevented colitis-associated tumorigenesis. Conclusions: Dicer was downregulated in inflamed colon tissues before malignancy occurred. Decreased Dicer expression further exaggerated inflammation, which may promote carcinogenesis. Anastrozole, berberine, and pranoprofen alleviated colitis and colitis-associated tumorigenesis by promoting Dicer expression. Our study provides insight into potential colitis treatment and colitis-associated colon cancer prevention strategies.

RNAInter in 2020: RNA interactome repository with increased coverage and annotation

Research on RNA-associated interactions has exploded in recent years, and increasing numbers of studies are not limited to RNA-RNA and RNA-protein interactions but also include RNA-DNA/compound interactions. To facilitate the development of the interactome and promote understanding of the biological functions and molecular mechanisms of RNA, we updated RAID v2.0 to RNAInter (RNA Interactome Database), a repository for RNA-associated interactions that is freely accessible at http://www.rna-society.org/rnainter/ or http://www.rna-society.org/raid/. Compared to RAID v2.0, new features in RNAInter include (i) 8-fold more interaction data and 94 additional species; (ii) more definite annotations organized, including RNA editing/localization/modification/structure and homology interaction; (iii) advanced functions including fuzzy/batch search, interaction network and RNA dynamic expression and (iv) four embedded RNA interactome tools: RIscoper, IntaRNA, PRIdictor and DeepBind. Consequently, RNAInter contains >41 million RNA-associated interaction entries, involving more than 450 thousand unique molecules, including RNA, protein, DNA and compound. Overall, RNAInter provides a comprehensive RNA interactome resource for researchers and paves the way to investigate the regulatory landscape of cellular RNAs.

Overexpression of miR-671-5p indicates a poor prognosis in colon cancer and accelerates proliferation, migration, and invasion of colon cancer cells

Purpose

Colon cancer is one of the common malignancies worldwide, and many genes, including microRNAs (miRNAs), have been demonstrated that associated with progression of various diseases, including cancers. The aim of this study is to investigate the potential role of miR-671-5p in colon cancer.

Patients and methods

Reverse transcription-quantitative polymerase chain reaction (qRT-PCR) was performed to detect the expression levels of miR-671-5p in 115 paired colon cancer tissues and adjacent normal tissues, as well as in colon cancer cells. Kaplan-Meier curve and Cox regression analyses were used to estimate the prognostic significance of miR-671-5p in colon cancer. CCK-8 assay, colony-formation assay, Transwell migration and invasion assays were used to evaluate the effects of miR-671-5p on cell proliferation, migration, and invasion in colon cancer.

Results

We found that miR-671-5p expression was increased in colon cancer tissues and cell lines. Overexpression of miR-671-5p was found associated with lymph node metastasis, TNM stage, and poor overall survival of patients with colon cancer. By exploiting miR-671-5p mimics and inhibitors, miR-671-5p overexpression significantly increased cell proliferation, migration, and invasion, while downregulation of miR-671-5p inhibited proliferation, migration, and invasion of colon cancer cells.

Conclusion

Taken together, miR-671-5p may act as an oncogene in colon cancer and promote proliferation, migration, and invasion of colon cancer cells by targeting TRIM67. And it may be a promising prognostic biomarker and therapeutic application for colon cancer treatment.

Pevonedistat, a Neuronal Precursor Cell-Expressed Developmentally Down-Regulated Protein 8-Activating Enzyme Inhibitor, Is a Potent Inhibitor of Hepatitis B Virus

Hepatitis B virus (HBV) infection is a major health concern worldwide. To prevent HBV-related mortality, elimination of viral proteins is considered the ultimate goal of HBV treatment; however, currently available nucleos(t)ide analogs rarely achieve this goal, as viral transcription from episomal viral covalently closed circular DNA (cccDNA) is not prevented. HBV regulatory protein X was recently found to target the protein structural maintenance of chromosomes 5/6 (Smc5/6) for ubiquitination and degradation by DDB1-CUL4-ROC1 E3 ligase, resulting in enhanced viral transcription from cccDNA. This ubiquitin-dependent proteasomal pathway requires an additional ubiquitin-like protein for activation, neuronal precursor cell-expressed developmentally down-regulated protein 8 (NEDD8). Here, we show that pevonedistat, a NEDD8-activating enzyme inhibitor, works efficiently as an antiviral agent. Pevonedistat significantly restored Smc5/6 protein levels and suppressed viral transcription and protein production in the HBV minicircle system in in vitro HBV replication models and in human primary hepatocytes infected naturally with HBV. Conclusion: These results indicate that pevonedistat is a promising compound to treat chronic HBV infection.

Integrative Analyses of Long Non-coding RNA and mRNA Involved in Piglet Ileum Immune Response to Clostridium perfringens Type C Infection

Long non-coding RNAs (lncRNAs) have been shown to play important roles in regulating host immune and inflammatory responses to bacterial infection. Infection with Clostridium perfringens (C. perfringens), a food-borne zoonotic pathogen, can lead to a series of inflammatory diseases in human and piglet, greatly challenging the healthy development of global pig industry. However, the roles of lncRNAs involved in piglet immune response against C. perfringens type C infection remain unknown. In this study, the regulatory functions of ileum lncRNAs and mRNAs were investigated in piglet immune response to C. perfringens type C infection among resistance (IR), susceptibility (IS) and sham-inoculation (control, IC) groups. A total of 480 lncRNAs and 3,669 mRNAs were significantly differentially expressed, the differentially expressed lncRNAs and mRNAs in the IR and IS groups were enriched in various pathways of ABC transporters, olfactory transduction, PPAR signaling pathway, chemokine signaling pathway and Toll-like receptor signaling pathway, involving in regulating piglet immune responses and resistance during infection. There were 212 lncRNAs and 505 target mRNAs found to have important association with C. perfringens infectious diseases, furthermore, 25 dysregulated lncRNAs corresponding to 13 immune-related target mRNAs were identified to play potential roles in defense against bacterial infection. In conclusion, the results improve our understanding on the characteristics of lncRNAs and mRNAs on regulating host immune response against C. perfringens type C infection, which will provide a reference for future research into exploring C. perfringens-related diseases in human.

Rho–ROCK signaling regulates tumor-microenvironment interactions

Reciprocal biochemical and biophysical interactions between tumor cells, stromal cells and the extracellular matrix (ECM) result in a unique tumor microenvironment that determines disease outcome. The cellular component of the tumor microenvironment contributes to tumor growth by providing nutrients, assisting in the infiltration of immune cells and regulating the production and remodeling of the ECM. The ECM is a noncellular component of the tumor microenvironment and provides both physical and biochemical support to the tumor cells. Rho–ROCK signaling is a key regulator of actomyosin contractility and regulates cell shape, cytoskeletal arrangement and thereby cellular functions such as cell proliferation, differentiation, motility and adhesion. Rho–ROCK signaling has been shown to promote cancer cell growth, migration and invasion. However, it is becoming clear that this pathway also regulates key tumor-promoting properties of the cellular and noncellular components of the tumor microenvironment. There is accumulating evidence that Rho–ROCK signaling enhances ECM stiffness, modifies ECM composition, increases the motility of tumor-associated fibroblasts and lymphocytes and promotes trans-endothelial migration of tumor-associated lymphocytes. In this review, we briefly discuss the current state of knowledge on the role of Rho–ROCK signaling in regulating the tumor microenvironment and the implications of this knowledge for therapy, potentially via the development of selective inhibitors of the components of this pathway to permit the tuning of signaling flux, including one example with demonstrated utility in pre-clinical models.

Integrative analysis of significant RNA-binding proteins in colorectal cancer metastasis

The aberrant expression of RNA-binding proteins (RBPs) plays a crucial role in the occurrence and progression of human cancer. However, the key functions of RBPs in the metastasis of colorectal cancer have not yet been fully elucidated. Here, we integrated multi-omics data and identified four differentially expressed RBPs (APOBEC3G, EEF1A2, EIF5AL1 and CELF3) in patients with colorectal cancer metastasis. To clarify the underlying molecular mechanisms, we systematically analyzed the genomic features and downstream regulatory relationships of the four RBPs. In a genomic level, the copy number variations of APOBEC3G, EEF1A2, and CELF3 demonstrated significantly differential distributions between metastatic and nonmetastatic patients. Besides that, combining sequence and expression information, we identified 436 putative RNA targets regulated by the four RBPs through strict multistep bioinformatics screening. For the downstream analysis, the evidence from functional enrichment analysis and public literature indicated the roles of these target genes in the carcinogenesis and progression of colorectal cancer. Furthermore, through the machine learning algorithm and statistical analysis, we obtained two gene candidates that had obvious effects on the metastasis and overall survival status of patients with colorectal cancer. In summary, our study comprehensively explored the influence of APOBEC3G, EEF1A2, EIF5AL1, and CELF3 in colorectal cancer metastasis, which may offer favorable perspectives for clinical diagnosis and therapy.

ISGF3 with reduced phosphorylation is associated with constitutive expression of interferon-induced genes in aging cells

During cellular aging, many changes in cellular functions occur. A hallmark of aged cells is secretion of inflammatory mediators, which collectively is referred to as the senescence-associated secretory phenotype (SASP). However, the mechanisms underlying such changes are unclear. Canonically, the expression of interferon (IFN)-stimulated genes (ISGs) is induced by IFNs through the formation of the tripartite transcriptional factor ISGF3, which is composed of IRF9 and the phosphorylated forms of STAT1 and STAT2. However, in this study, the constitutive expression of ISGs in human-derived senescent fibroblasts and in fibroblasts from a patient with Werner syndrome, which leads to premature aging, was mediated mainly by the unphosphorylated forms of STATs in the absence of INF production. Under homeostatic conditions, STAT1, STAT2, and IRF9 were localized to the nucleus of aged cells. Although knockdown of JAK1, a key kinase of STAT1 and STAT2, did not affect ISG expression or IFN-stimulated response element (ISRE)-mediated promoter activities in these senescent cells, knockdown of STAT1 or STAT2 decreased ISG expression and ISRE activities. These results suggest that the ISGF3 complex without clear phosphorylation is required for IFN-independent constitutive ISG transcription in senescent cells.

Inhibition of HBV Transcription From cccDNA With Nitazoxanide by Targeting the HBx-DDB1 Interaction

BACKGROUND & AIMS

Hepatitis B virus (HBV) infection is a major health concern worldwide. Although currently used nucleos(t)ide analogs efficiently inhibit viral replication, viral proteins transcribed from the episomal viral covalently closed circular DNA (cccDNA) minichromosome continue to be expressed long-term. Because high viral RNA or antigen loads may play a biological role during this chronicity, the elimination of viral products is an ultimate goal of HBV treatment. HBV regulatory protein X (HBx) was recently found to promote transcription of cccDNA with degradation of Smc5/6 through the interaction of HBx with the host protein DDB1. Here, this protein-protein interaction was considered as a new molecular target of HBV treatment.

METHODS

To identify candidate compounds that target the HBx-DDB1 interaction, a newly constructed split luciferase assay system was applied to comprehensive compound screening. The effects of the identified compounds on HBV transcription and cccDNA maintenance were determined using HBV minicircle DNA, which mimics HBV cccDNA, and the natural HBV infection model of human primary hepatocytes.

RESULTS

We show that nitazoxanide (NTZ), a thiazolide anti-infective agent that has been approved by the FDA for protozoan enteritis, efficiently inhibits the HBx-DDB1 protein interaction. NTZ significantly restores Smc5 protein levels and suppresses viral transcription and viral protein production in the HBV minicircle system and in human primary hepatocytes naturally infected with HBV.

CONCLUSIONS

These results indicate that NTZ, which targets an HBV-related viral-host protein interaction, may be a promising new therapeutic agent and a step toward a functional HBV cure.

Satellite RNA Increases DNA Damage and Accelerates Tumor Formation in Mouse Models of Pancreatic Cancer

Highly repetitive tandem arrays such as satellite sequences in the centromeric and pericentromeric regions of chromosomes, which were previously considered to be silent, are actively transcribed in various biological processes, including cancers. In the pancreas, this aberrant expression occurs even in Kras-mutated pancreatic intraepithelial neoplasia (PanIN) tissues, which are precancerous lesions. To determine the biological role of satellite RNAs in carcinogenesis in vivo, we constructed mouse major satellite (MajSAT) RNA-expressing transgenic mice. However, these transgenic mice did not show spontaneous malignant tumor formation under normal breeding. Importantly, however, DNA damage was increased in pancreatic tissues induced by caerulein treatment or high-fat diet, which may be due to impaired nuclear localization of Y-Box Binding Protein 1 (YBX1), a component of the DNA damage repair machinery. In addition, when crossed with pancreas-specific Kras-mutant mice, MajSAT RNA expression resulted in an earlier increase in PanIN formation. These results suggest that aberrant MajSAT RNA expression accelerates oncogenesis by increasing the probability of a second driver mutation, thus accelerating cells to exit from the breakthrough phase to the expansion phase.Implications: Aberrant expression of satellite RNAs accelerates oncogenesis through a mechanism involving increased DNA damage. Mol Cancer Res; 16(8); 1255-62. ©2018 AACR.

miR-130a and miR-212 Disrupt the Intestinal Epithelial Barrier through Modulation of PPARγ and Occludin Expression in Chronic Simian Immunodeficiency Virus-Infected Rhesus Macaques

Intestinal epithelial barrier dysfunction is a well-known sequela of HIV/SIV infection that persists despite antiretroviral therapy. Although inflammation is a triggering factor, the underlying molecular mechanisms remain unknown. Emerging evidence suggests that epithelial barrier function is epigenetically regulated by inflammation-induced microRNAs (miRNAs). Accordingly, we profiled and characterized miRNA/mRNA expression exclusively in colonic epithelium and identified 46 differentially expressed miRNAs (20 upregulated and 26 downregulated) in chronically SIV-infected rhesus macaques (Macaca mulatta). We bioinformatically crossed the predicted miRNA targets to transcriptomic data and characterized miR-130a and miR-212 as both were predicted to interact with critical epithelial barrier-associated genes. Next, we characterized peroxisome proliferator-activated receptor γ (PPARγ) and occludin (OCLN), predicted targets of miR-130a and miR-212, respectively, as their downregulation has been strongly linked to epithelial barrier disruption and dysbiosis. Immunofluorescence, luciferase reporter, and overexpression studies confirmed the ability of miR-130a and miR-212 to decrease protein expression of PPARγ and OCLN, respectively, and reduce transepithelial electrical resistance. Because Δ-9-tetrahydrocannabinol exerted protective effects in the intestine in our previous studies, we successfully used it to reverse miR-130a- and miR-212-mediated reduction in transepithelial electrical resistance. Finally, ex vivo Δ-9-tetrahydrocannabinol treatment of colon tissue from chronically SIV-infected rhesus macaques significantly increased PPARγ expression. Our findings suggest that dysregulated miR-130a and miR-212 expression in colonic epithelium during chronic HIV/SIV infection can facilitate epithelial barrier disruption by downregulating OCLN and PPARγ expression. Most importantly, our results highlight the beneficial effects of cannabinoids on epithelial barrier function in not just HIV/SIV but potentially other chronic intestinal inflammatory diseases.