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1.
Clin Sci (Lond) ; 134(2): 225-237, 2020 01 31.
Artículo en Inglés | MEDLINE | ID: mdl-31934720

RESUMEN

Circulating factors have been implicated in the pathogenesis of minimal change disease (MCD), and may have direct effects on cholesterol metabolism. This study investigated the pathogenesis of hypercholesterolemia in an IL-13 overexpression rat model of MCD prior to the onset of proteinuria, so as to establish the direct contribution of IL-13, especially with regard to hepatic cholesterol handling. In this model of MCD, the temporal relationship between hypercholesterolemia and proteinuria was first identified. Plasma proprotein convertase subtilisin/kexin type 9 (Pcsk9) and liver ATP-binding cassette sub-family G member 5 (Abcg5) were measured using ELISA. Liver Ldlr and liver X receptor alpha (Lxra) were quantified with Western blot. Abcg5-mediated cholesterol efflux in IL-13-stimulated rat primary hepatocytes was measured using taurocholate as cholesterol acceptor. The role of Lxra was validated using a luciferase assay in Lxre-luciferase-transfected IL-13-stimulated hepatocytes. IL-13-transfected rats developed hypercholesterolemia prior to proteinuria, with 35% of rats hypercholesterolemic but only 11% proteinuric by Day 20 (P = 0.04). These pre-proteinuric hypercholesterolemic rats showed elevations in total and LDL-cholesterol, but not hypertriglyceridemia or hepatic steatosis. The hypercholesterolemia was associated with increased hepatic Pcsk9 synthesis and enhanced circulating Pcsk9 levels, which correlated strongly with plasma total cholesterol (r = 0.73, P<0.001). The hypercholesterolemia was also contributed by decreased Abcg5 expression and activity, due to reduced Lxra expression. Lxra expression correlated with plasma total cholesterol levels (r = -0.52, P = 0.01), and overexpression of pLxra in rat hepatocytes abrogated the IL-13-mediated down-regulation of Lxre-driven gene expression. In conclusion, we have shown that IL-13 induced changes in hepatic cholesterol handling in a cytokine-induced rat model of MCD, resulting in hypercholesterolemia which can precede the onset of proteinuria.


Asunto(s)
Colesterol/metabolismo , Hipercolesterolemia/metabolismo , Interleucina-13/metabolismo , Hígado/metabolismo , Nefrosis Lipoidea/metabolismo , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 5/metabolismo , Animales , Colesterol/sangre , Modelos Animales de Enfermedad , Regulación hacia Abajo , Hipercolesterolemia/sangre , Hipercolesterolemia/complicaciones , Lipoproteínas/metabolismo , Receptores X del Hígado/metabolismo , Masculino , Nefrosis Lipoidea/sangre , Nefrosis Lipoidea/complicaciones , Proproteína Convertasa 9/metabolismo , Proteinuria/complicaciones , Proteinuria/metabolismo , Ratas Wistar , Proteínas de Unión a los Elementos Reguladores de Esteroles/metabolismo
2.
Pharmacogenomics J ; 19(6): 516-527, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31578463

RESUMEN

Drug response variations amongst different individuals/populations are influenced by several factors including allele frequency differences of single nucleotide polymorphisms (SNPs) that functionally affect drug-response genes. Here, we aim to identify drugs that potentially exhibit population differences in response using SNP data mining and analytics. Ninety-one pairwise-comparisons of >22,000,000 SNPs from the 1000 Genomes Project, across 14 different populations, were performed to identify 'population-differentiated' SNPs (pdSNPs). Potentially-functional pdSNPs (pf-pdSNPs) were then selected, mapped into genes, and integrated with drug-gene databases to identify 'population-differentiated' drugs enriched with genes carrying pf-pdSNPs. 1191 clinically-approved drugs were found to be significantly enriched (Z > 2.58) with genes carrying SNPs that were differentiated in one or more population-pair comparisons. Thirteen drugs were found to be enriched with such differentiated genes across all 91 population-pairs. Notably, 82% of drugs, which were previously reported in the literature to exhibit population differences in response were also found by this method to contain a significant enrichment of population specific differentiated SNPs. Furthermore, drugs with genetic testing labels, or those suspected to cause adverse reactions, contained a significantly larger number (P < 0.01) of population-pairs with enriched pf-pdSNPs compared with those without these labels. This pioneering effort at harnessing big-data pharmacogenomics to identify 'population differentiated' drugs could help to facilitate data-driven decision-making for a more personalized medicine.


Asunto(s)
Genoma Humano/genética , Preparaciones Farmacéuticas/metabolismo , Polimorfismo de Nucleótido Simple/genética , Transducción de Señal/genética , Frecuencia de los Genes/genética , Genética de Población/métodos , Humanos , Farmacogenética , Medicina de Precisión/métodos
3.
J Transl Med ; 17(1): 273, 2019 08 20.
Artículo en Inglés | MEDLINE | ID: mdl-31429776

RESUMEN

BACKGROUND: Hepatocellular carcinoma is the second most deadly cancer with late presentation and limited treatment options, highlighting an urgent need to better understand HCC to facilitate the identification of early-stage biomarkers and uncover therapeutic targets for the development of novel therapies for HCC. METHODS: Deep transcriptome sequencing of tumor and paired non-tumor liver tissues was performed to comprehensively evaluate the profiles of both the host and HBV transcripts in HCC patients. Differential gene expression patterns and the dys-regulated genes associated with clinical outcomes were analyzed. Somatic mutations were identified from the sequencing data and the deleterious mutations were predicted. Lastly, human-HBV chimeric transcripts were identified, and their distribution, potential function and expression association were analyzed. RESULTS: Expression profiling identified the significantly upregulated TP73 as a nodal molecule modulating expression of apoptotic genes. Approximately 2.5% of dysregulated genes significantly correlated with HCC clinical characteristics. Of the 110 identified genes, those involved in post-translational modification, cell division and/or transcriptional regulation were upregulated, while those involved in redox reactions were downregulated in tumors of patients with poor prognosis. Mutation signature analysis identified that somatic mutations in HCC tumors were mainly non-synonymous, frequently affecting genes in the micro-environment and cancer pathways. Recurrent mutations occur mainly in ribosomal genes. The most frequently mutated genes were generally associated with a poorer clinical prognosis. Lastly, transcriptome sequencing suggest that HBV replication in the tumors of HCC patients is rare. HBV-human fusion transcripts are a common observation, with favored HBV and host insertion sites being the HBx C-terminus and gene introns (in tumors) and introns/intergenic-regions (in non-tumors), respectively. HBV-fused genes in tumors were mainly involved in RNA binding while those in non-tumors tissues varied widely. These observations suggest that while HBV may integrate randomly during chronic infection, selective expression of functional chimeric transcripts may occur during tumorigenesis. CONCLUSIONS: Transcriptome sequencing of HCC patients reveals key cancer molecules and clinically relevant pathways deregulated/mutated in HCC patients and suggests that while HBV may integrate randomly during chronic infection, selective expression of functional chimeric transcripts likely occur during the process of tumorigenesis.


Asunto(s)
Carcinoma Hepatocelular/genética , Perfilación de la Expresión Génica , Neoplasias Hepáticas/genética , Transcriptoma/genética , Secuencia de Bases , Ciclo Celular/genética , Cromosomas Humanos/genética , Regulación Neoplásica de la Expresión Génica , Genoma Viral , Virus de la Hepatitis B/genética , Humanos , Intrones/genética , Masculino , Mutación/genética , Sistemas de Lectura Abierta/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Secuencias Repetitivas de Ácidos Nucleicos , Análisis de Supervivencia , Transactivadores/genética , Proteínas Reguladoras y Accesorias Virales
4.
Hum Genomics ; 12(1): 43, 2018 09 15.
Artículo en Inglés | MEDLINE | ID: mdl-30219098

RESUMEN

BACKGROUND: Genetic polymorphisms can contribute to phenotypic differences amongst individuals, including disease risk and drug response. Characterization of genetic polymorphisms that modulate gene expression and/or protein function may facilitate the identification of the causal variants. Here, we present the architecture of genetic polymorphisms in the human genome focusing on those predicted to be potentially functional/under natural selection and the pathways that they reside. RESULTS: In the human genome, polymorphisms that directly affect protein sequences and potentially affect function are the most constrained variants with the lowest single-nucleotide variant (SNV) density, least population differentiation and most significant enrichment of rare alleles. SNVs which potentially alter various regulatory sites, e.g. splicing regulatory elements, are also generally under negative selection. Interestingly, genes that regulate the expression of transcription/splicing factors and histones are conserved as a higher proportion of these genes is non-polymorphic, contain ultra-conserved elements (UCEs) and/or has no non-synonymous SNVs (nsSNVs)/coding INDELs. On the other hand, major histocompatibility complex (MHC) genes are the most polymorphic with SNVs potentially affecting the binding of transcription/splicing factors and microRNAs (miRNA) exhibiting recent positive selection (RPS). The drug transporter genes carry the most number of potentially deleterious nsSNVs and exhibit signatures of RPS and/or population differentiation. These observations suggest that genes that interact with the environment are highly polymorphic and targeted by RPS. CONCLUSIONS: In conclusion, selective constraints are observed in coding regions, master regulator genes, and potentially functional SNVs. In contrast, genes that modulate response to the environment are highly polymorphic and under positive selection.


Asunto(s)
Sustitución de Aminoácidos/genética , Genoma Humano/genética , Inmunidad Innata/genética , Selección Genética/genética , Alelos , Humanos , Mutación INDEL/genética , MicroARNs/genética , Polimorfismo de Nucleótido Simple/genética , Empalme del ARN/genética , Secuencias Reguladoras de Ácidos Nucleicos/genética
5.
Hepatology ; 61(4): 1416-24, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25099228

RESUMEN

Chronic infection with hepatitis B virus (HBV) is a risk factor for developing hepatocellular carcinoma (HCC). The life cycle of HBV is complex and has been difficult to study because HBV does not infect cultured cells. The HBV regulatory X protein (HBx) controls the level of HBV replication and possesses an HCC cofactor role. Attempts to understand the mechanism(s) that underlie HBx effects on HBV replication and HBV-associated carcinogenesis have led to many reported HBx activities that are likely influenced by the assays used. This review summarizes experimental systems commonly used to study HBx functions, describes limitations of these experimental systems that should be considered, and suggests approaches for ensuring the biological relevance of HBx studies.


Asunto(s)
Transactivadores/fisiología , Virología/métodos , Virología/normas , Virus de la Hepatitis B/fisiología , Humanos , Neoplasias Hepáticas/virología , Proyectos de Investigación/normas , Proteínas Reguladoras y Accesorias Virales , Fenómenos Fisiológicos de los Virus
6.
Int J Mol Sci ; 17(6)2016 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-27314335

RESUMEN

Chronic hepatitis B virus (HBV) infection is one of the most associated factors in hepatocarcinogenesis. HBV is able to integrate into the host genome and encode the multi-functional hepatitis B virus x protein (HBx). Although the mechanism between HBx and carcinogenesis is still elusive, recent studies have shown that HBx was able to influence various signaling pathways, as well as epigenetic and genetic processes. This review will examine and summarize recent literature about HBx's role in these various processes.


Asunto(s)
Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Transactivadores/metabolismo , Animales , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/virología , Epigénesis Genética , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/virología , Transducción de Señal , Transactivadores/genética , Proteínas Reguladoras y Accesorias Virales
7.
Carcinogenesis ; 35(4): 923-34, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24325913

RESUMEN

FAT10 (HLA-F-adjacent transcript 10) is an ubiquitin-like modifier, which has been implicated in immune response and cancer development. In particular, the hypothesis of FAT10 as a mediator of tumorigenesis stems from its ability to associate with a spindle checkpoint protein Mad2 during mitosis and cause aneuploidy, a hallmark of cancer cells. Furthermore, FAT10 is overexpressed in several carcinomas types, including that of liver and colon. Nevertheless, direct evidence linking FAT10 to cell malignant transformation and progression is lacking. Here, we demonstrate that high FAT10 expression enhanced the proliferative, invasive, migratory and adhesive functions of the transformed cell line, HCT116. These observations were consistently demonstrated in an immortalized, non-tumorigenic liver cell line NeHepLxHT. Importantly, FAT10 can induce malignant transformation as evidenced from the anchorage-independent growth as well as in vivo tumor-forming abilities of FAT10-overexpressing NeHepLxHT cells, whereas in rapidly proliferating HCT116, increased FAT10 further augmented tumor growth. FAT10 was found to activate nuclear factor-κB (NFκB), which in turn upregulated the chemokine receptors CXCR4 and CXCR7. Importantly, small interfering RNA depletion of CXCR7 and CXCR4 attenuated cell invasion of FAT10-overexpressing cells, indicating that the CXCR4/7 is crucial for the FAT10-dependent malignant phenotypes. Taken together, our data reveal novel functions of FAT10 in malignant transformation and progression, via the NFκB-CXCR4/7 pathway.


Asunto(s)
Ubiquitinas/fisiología , Animales , Secuencia de Bases , Adhesión Celular , Línea Celular Transformada , Línea Celular Tumoral , Neoplasias del Colon/metabolismo , Neoplasias del Colon/patología , Cartilla de ADN , Progresión de la Enfermedad , Humanos , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patología , Ratones , Ratones Desnudos , Invasividad Neoplásica , Metástasis de la Neoplasia , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ubiquitinas/metabolismo
8.
Carcinogenesis ; 34(4): 787-98, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23276797

RESUMEN

Chronic hepatitis B virus (HBV) infection is epidemiologically associated with hepatocellular carcinoma (HCC), but its role in HCC remains poorly understood due to technological limitations. In this study, we systematically characterize HBV in HCC patients. HBV sequences were enriched from 48 HCC patients using an oligo-bead-based strategy, pooled together and sequenced using the FLX-Genome-Sequencer. In the tumors, preferential integration of HBV into promoters of genes (P < 0.001) and significant enrichment of integration into chromosome 10 (P < 0.01) were observed. Integration into chromosome 10 was significantly associated with poorly differentiated tumors (P < 0.05). Notably, in the tumors, recurrent integration into the promoter of the human telomerase reverse transcriptase (TERT) gene was found to correlate with increased TERT expression. The preferred region within the HBV genome involved in integration and viral structural alteration is at the 3'-end of hepatitis B virus X protein (HBx), where viral replication/transcription initiates. Upon integration, the 3'-end of the HBx is often deleted. HBx-human chimeric transcripts, the most common type of chimeric transcripts, can be expressed as chimeric proteins. Sequence variation resulting in non-conservative amino acid substitutions are commonly observed in HBV genome. This study highlights HBV as highly mutable in HCC patients with preferential regions within the host and virus genome for HBV integration/structural alterations.


Asunto(s)
Carcinoma Hepatocelular/virología , Virus de la Hepatitis B/genética , Neoplasias Hepáticas/virología , Telomerasa/genética , Sustitución de Aminoácidos , Secuencia de Bases , Carcinoma Hepatocelular/complicaciones , Carcinoma Hepatocelular/genética , Línea Celular , Cromosomas Humanos Par 10/virología , ADN Viral/genética , Variación Genética , Hepatitis B Crónica/complicaciones , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Neoplasias Hepáticas/genética , Regiones Promotoras Genéticas , Análisis de Secuencia de ADN , Telomerasa/biosíntesis , Transactivadores/genética , Proteínas Reguladoras y Accesorias Virales , Integración Viral/genética
9.
J Cell Sci ; 124(Pt 21): 3665-75, 2011 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-22025632

RESUMEN

Tumor necrosis factor-alpha (TNF-α) plays important roles in chronic inflammation-associated tumorigenesis but the mechanisms involved remain poorly understood. Previously, we reported that high levels of FAT10 led to chromosomal instability that is mediated by an abbreviated mitotic phase. Here, we show that TNF-α induces FAT10 gene expression through TNF receptor 1 (TNFR1) and activates the NF-κB pathway in HCT116 and SW620 cells. TNF-α treatment also leads to an abbreviated mitotic phase that can be reversed by inhibiting FAT10 expression. This abbreviated mitotic phase is correlated with a TNF-α-induced reduction in the kinetochore localization of MAD2 during prometaphase which, again, can be reversed by inhibiting FAT10 gene expression. There is greater variability of chromosome numbers in HCT116 and SW620 cells treated with TNF-α than in untreated cells, which can be reversed by the introduction of short hairpin RNA (shRNA) against FAT10. The more stable chromosome numbers in HCT116 cells expressing FAT10 shRNA can revert to greater variability with the addition of a mutant FAT10 that is not recognized by the FAT10 shRNA. Upon TNF-α stimulation, higher cell death is observed when FAT10 expression is inhibited by shRNA. These data strongly suggest that FAT10 plays an important role in mediating the function of TNF-α during tumorigenesis by inducing cell cycle deregulation and chromosomal instability, and by inhibiting apoptosis.


Asunto(s)
Inestabilidad Cromosómica , Neoplasias/genética , Factor de Necrosis Tumoral alfa/metabolismo , Ubiquitinas/metabolismo , Ciclo Celular , Línea Celular Tumoral , Humanos , Neoplasias/metabolismo , Neoplasias/fisiopatología , Receptores Tipo I de Factores de Necrosis Tumoral/genética , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Factor de Necrosis Tumoral alfa/genética , Ubiquitinas/genética
10.
FASEB J ; 26(7): 3032-41, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22459148

RESUMEN

MicroRNA-224 (miR-224) is one of the most commonly up-regulated microRNAs in hepatocellular carcinoma (HCC), which affects crucial cellular processes such as apoptosis and cell proliferation. In this study, we aim to elucidate the molecular mechanism that leads to the overexpression of miR-224 in HCC. We examined the transcript expression of miR-224 and neighboring miR-452 and genes on chromosome Xq28 in tumor and paired adjacent nontumorous tissues from 100 patients with HCC and found that miR-224 is coordinately up-regulated with its neighboring microRNA (miRNA) and genes. This coordinated up-regulation of miRNAs and genes at the Xq28 locus can be mimicked in nontransformed immortalized human liver cells by the introduction of histone deacetylase (HDAC) inhibitors, which resulted in a corresponding increase in histone H3 acetylation in this region. This miR-224-residing locus in Xq28 is reciprocally regulated by HDAC1, HDAC3, and histone acetylase protein, E1A binding protein p300 (EP300). Notably, in HCC tumors that significantly overexpress microRNA-224, EP300 is also overexpressed and displays increased binding to the Xq28 locus. In transformed HCC cells, high miR-224 expression can be attenuated through the inhibition of EP300, using either siRNA or the specific drug C646. In summary, overexpression of EP300 may account, in part, for the up-regulation of miR-224 expression in patients with HCC.


Asunto(s)
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , MicroARNs/genética , ARN Neoplásico/genética , Acetilación , Secuencia de Bases , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Carcinoma Hepatocelular/metabolismo , Cromosomas Humanos X/genética , Cartilla de ADN/genética , Proteína p300 Asociada a E1A/antagonistas & inhibidores , Proteína p300 Asociada a E1A/genética , Proteína p300 Asociada a E1A/metabolismo , Epigénesis Genética , Células Hep G2 , Histona Desacetilasa 1/antagonistas & inhibidores , Histona Desacetilasa 1/genética , Histona Desacetilasa 1/metabolismo , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Histonas/química , Histonas/metabolismo , Humanos , Neoplasias Hepáticas/metabolismo , MicroARNs/metabolismo , ARN Neoplásico/metabolismo , ARN Interferente Pequeño/genética , Regulación hacia Arriba
11.
Hum Mutat ; 32(1): 19-24, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20672376

RESUMEN

Currently, >14,000,000 single nucleotide polymorphisms (SNPs) are reported. Identifying phenotype-affecting SNPs among these many SNPs pose significant challenges. Although several Web resources are available that can inform about the functionality of SNPs, these resources are mainly annotation databases and are not very comprehensive. In this article, we present a comprehensive, well-annotated, integrated pfSNP (potentially functional SNPs) Web resource (http://pfs.nus.edu.sg/), which is aimed to facilitate better hypothesis generation through knowledge syntheses mediated by better data integration and a user-friendly Web interface. pfSNP integrates >40 different algorithms/resources to interrogate >14,000,000 SNPs from the dbSNP database for SNPs of potential functional significance based on previous published reports, inferred potential functionality from genetic approaches as well as predicted potential functionality from sequence motifs. Its query interface has the user-friendly "auto-complete, prompt-as-you-type" feature and is highly customizable, facilitating different combination of queries using Boolean-logic. Additionally, to facilitate better understanding of the results and aid in hypotheses generation, gene/pathway-level information with text clouds highlighting enriched tissues/pathways as well as detailed-related information are also provided on the results page. Hence, the pfSNP resource will be of great interest to scientists focusing on association studies as well as those interested to experimentally address the functionality of SNPs.


Asunto(s)
Biología Computacional , Bases de Datos Genéticas , Polimorfismo de Nucleótido Simple/genética , Humanos , Internet , Programas Informáticos/normas
12.
Arch Biochem Biophys ; 509(2): 164-9, 2011 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-21396347

RESUMEN

FAT10, also known as diubiquitin, has been implicated in the regulation of diverse cellular processes, including mitosis, immune response, and apoptosis. We seek to identify FAT10-targeted proteins, an essential step in elucidating the physiological function of FAT10. To this end, human FAT10 or its non-conjugatable derivative, FAT10ΔGG, was overexpressed in HEK293 cells. We observed a number of high molecular weight FAT10 conjugates in cells expressing wild-type FAT10, but not in FAT10ΔGG. The FAT10 conjugates are inducible by TNF-α and accumulated significantly when cells were treated with proteasome inhibitor, MG132. Among them, tumor suppressor p53 was found to be FATylated. The p53 transcriptional activity was found to be substantially enhanced in FAT10-overexpressing cells. In addition, overexpressing FAT10 in HEK293 cells also reduced the population of p53 which cross reacted with monoclonal anti-p53 antibody, PAB240, known to recognize only the transcriptionally inactive p53. FAT10 in the nucleus was found co-localized with p53 and altered its subcellular compartmentalization. Furthermore, overexpressing FAT10 led to a reduction in the size of promyelocytic leukemia nuclear bodies (PML-NBs) and altered their distribution in the nucleus. Based on these observations, a potential mechanism which correlates FATylation of p53 to its translocation and transcriptional activation is discussed.


Asunto(s)
Activación Transcripcional , Proteína p53 Supresora de Tumor/genética , Ubiquitinas/metabolismo , Células HEK293 , Humanos , Cuerpos de Inclusión Intranucleares/metabolismo , Leucemia Promielocítica Aguda/genética , Leucemia Promielocítica Aguda/metabolismo , Conformación Proteica , Proteína p53 Supresora de Tumor/análisis , Proteína p53 Supresora de Tumor/metabolismo , Ubiquitinas/análisis , Ubiquitinas/genética , Regulación hacia Arriba
13.
J Hepatol ; 53(1): 57-66, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20447714

RESUMEN

BACKGROUND & AIMS: The pleiotropic hepatitis B virus (HBV) x protein (HBx), associated with hepatocellular carcinoma (HCC), has been implicated in the deregulation of cellular gene expression at the transcriptional level. To date, it remains unknown if HBx regulates the expression of miRNAs which play important roles in gene-regulation at the post-transcriptional and/or translational level. METHODS: miRNA microarrays were employed to compare the expression of cellular miRNAs in HBx-versus control-HepG2 cells. Reverse-transcription Taqman realtime-PCR was used to examine let-7a expression in normal liver as well as paired HCC-tumor and adjacent non-tumorous liver. Let-7a miRNA was functionally characterized in cells with transiently altered let-7a expression. The direct target of let-7a was identified in silico and validated using 3'UTR-reporter assay. RESULTS: HBx up-regulates 7 and down-regulates 11 miRNAs, including the let-7 family. HBx expression was found to have a significant inverse correlation with the expression of the highly-expressed members of the let-7 family in HCC patients, highlighting the clinical relevance of our observations. Further characterization of let-7a, the most highly expressed let-7 family member, revealed that it negatively regulates cellular proliferation partly through targeting signal transducer and activator of transcription 3 (STAT3). HBx-mediated down-regulation of let-7a and up-regulation of STAT3 supports cell proliferation in HBx cells. CONCLUSION: This study thus represents the first demonstration of HBx's ability to deregulate cellular miRNA expression. The deregulation of the expression of the let-7 family of miRNAs by HBx may represent a potential novel pathway through which HBx acts to deregulate cell proliferation leading to hepatocarcinogenesis.


Asunto(s)
Virus de la Hepatitis B/metabolismo , MicroARNs/genética , Factor de Transcripción STAT3/metabolismo , Transactivadores/metabolismo , Regiones no Traducidas 3' , Apoptosis/genética , Apoptosis/fisiología , Secuencia de Bases , Carcinoma Hepatocelular/etiología , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Línea Celular Tumoral , Proliferación Celular , Regulación hacia Abajo , Virus de la Hepatitis B/genética , Virus de la Hepatitis B/patogenicidad , Humanos , Neoplasias Hepáticas/etiología , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , ARN Interferente Pequeño/genética , Factor de Transcripción STAT3/antagonistas & inhibidores , Factor de Transcripción STAT3/genética , Transactivadores/genética , Transfección , Proteínas Reguladoras y Accesorias Virales
14.
J Cell Mol Med ; 13(1): 12-23, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19175697

RESUMEN

MicroRNAs (miRs) are small non-coding RNAs regulating gene expression at the post-transcriptional and/or translational levels. miRs play important roles in diverse biological processes, including development, cell differentiation, proliferation and apoptosis. Recent evidence has shown that miR loci frequently map to cancer-associated genomic regions and deregulated miR expression profiles are associated with many cancer types, implicating miRs in crucial processes that lead to tumourigenesis. Here, we review the current findings about miRs and tumourigenesis, focusing on their involvement in the apoptosis pathway. A significant observation is that greater than one-quarter of all known human miRs were reported to be deregulated in at least one cancer type. The expression of a subset of miRs (e.g. miR-21 and miR-155) was found to be consistently up-regulated, whereas another subset of miRs (e.g.miR-143 and miR-145) was consistently down-regulated across different cancer types suggesting their involvement in regulating common cellular processes whose deregulation may lead to tumourigenesis. Several miRs were implicated to play roles in cell proliferation and apoptosis. Some miRs, such as miR-29b and miR-15-16, influence only the apoptotic pathway, whereas others including let-7/miR-98 and miR-17-92 may play roles in both the apoptotic and cell-proliferation pathways. In conclusion, although our current understanding of the functions of miRs is still fragmentary, taken together, this review highlights the complex and intricate roles that miRs play in the regulation of cellular processes. Perturbation of the expression of miRs may thus lead to tumourigenesis.


Asunto(s)
Apoptosis/fisiología , MicroARNs , Neoplasias/genética , Animales , Proteínas Reguladoras de la Apoptosis/genética , Proteínas Reguladoras de la Apoptosis/metabolismo , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Fosfohidrolasa PTEN/genética , Fosfohidrolasa PTEN/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Transducción de Señal/fisiología
15.
PLoS One ; 14(10): e0224089, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31622447

RESUMEN

Population variation in disease and other phenotype are partly attributed to single nucleotide polymorphisms (SNPs) in the human genome. Due to selection pressure, two individuals from the same ancestral population have more genetic similarity compared to individuals from further geographic regions. Here, we elucidated the genomic population differentiation pattern, by interrogating >22,000,000 SNPs. Majority of population-differentiated (pd) SNPs (~95%), including the potentially functional (pf) (~84%) subset reside in non-genic regions, compared to the proportion of all SNPs (58%) found in non-genic regions. This suggests that differences between populations are more likely due to differences in gene regulation rather than protein function. Actin Cytoskeleton, Axonal Guidance and Protein Kinase A signaling pathways are enriched with genes carrying at least three pdSNPs (enriched pdGenes), while Antigen Presentation, Hepatic Fibrosis and Huntington Disease Signalling pathways are over-represented by enriched pf-pdGenes. An inverse correlation between chromosome size and the proportion of pd-/pf-pdSNPs was observed. Smaller chromosomes have relatively more of such SNPs including genes carrying these SNPs. Genes associated with common diseases and enriched with these pd-/pfpdSNPs are localized to 11 different chromosomes, with immune-related disease pd/pf-pdGenes mainly residing in chromosome 6 while neurological disease pd/pf-pdGenes residing in smaller chromosomes including chromosome 21/22. The associated diseases were reported to show population differences in incidence, severity and/or etiology. In summary, this study highlights the non-sporadic nature of population differentiation footprint in the human genome, which can potentially lead to the identification of genomic regions that play roles in the manifestation of phenotypic differences, including in disease predisposition and drug response.


Asunto(s)
Genoma Humano , Polimorfismo de Nucleótido Simple , Citoesqueleto de Actina/genética , Regulación de la Expresión Génica/genética , Genética de Población , Humanos , Transducción de Señal/genética
16.
Sci Rep ; 9(1): 10464, 2019 07 18.
Artículo en Inglés | MEDLINE | ID: mdl-31320713

RESUMEN

Hepatocellular carcinoma (HCC) is the fifth most common cancer with high mortality, due to late diagnosis and limited treatment options. Blood miRNAs, which circulate in a highly stable, cell-free form, show promise as novel potential biomarkers for early detection of HCC. Whole miRNome profiling was performed to identify deregulated miRNAs between HCC and normal healthy (NH) volunteers. These deregulated miRNAs were validated in an independent cohort of HCC, NH and chronic Hepatitis B (CHB) volunteers and finally in a 3rd cohort comprising NH, CHB, cirrhotic and HCC volunteers to evaluate miRNA changes during disease progression. The associations between circulating miRNAs and liver-damage markers, clinicopathological characteristics and survival outcomes were analysed to identify prognostic markers. Twelve miRNAs are differentially expressed between HCC and NH individuals in all three cohorts. Five upregulated miRNAs (miR-122-5p, miR-125b-5p, miR-885-5p, miR-100-5p and miR-148a-3p) in CHB, cirrhosis and HCC patients are potential biomarkers for CHB infection, while miR-34a-5p can be a biomarker for cirrhosis. Notably, four miRNAs (miR-1972, miR-193a-5p, miR-214-3p and miR-365a-3p) can distinguish HCC from other non-HCC individuals. Six miRNAs are potential prognostic markers for overall survival.


Asunto(s)
Biomarcadores de Tumor/genética , Carcinoma Hepatocelular/patología , Detección Precoz del Cáncer/métodos , Regulación Neoplásica de la Expresión Génica , Hepatitis B Crónica/complicaciones , Cirrosis Hepática/patología , MicroARNs/genética , Biomarcadores de Tumor/sangre , Carcinoma Hepatocelular/sangre , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/virología , Estudios de Casos y Controles , Progresión de la Enfermedad , Femenino , Estudios de Seguimiento , Perfilación de la Expresión Génica , Virus de la Hepatitis B/aislamiento & purificación , Hepatitis B Crónica/virología , Humanos , Cirrosis Hepática/sangre , Cirrosis Hepática/genética , Cirrosis Hepática/virología , Neoplasias Hepáticas/sangre , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patología , Neoplasias Hepáticas/virología , Masculino , MicroARNs/sangre , Persona de Mediana Edad , Pronóstico , Tasa de Supervivencia
17.
Genes (Basel) ; 9(7)2018 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-29949944

RESUMEN

FAT10, which is also known as diubiquitin, has been implicated to play important roles in immune regulation and tumorigenesis. Its expression is up-regulated in the tumors of Hepatocellular Carcinoma (HCC) and other cancer patients. High levels of FAT10 in cells have been shown to result in increased mitotic non-disjunction and chromosome instability, leading to tumorigenesis. To evaluate whether the aberrant up-regulation of the FAT10 gene in the tumors of HCC patients is due to mutations or the aberrant methylation of CG dinucleotides at the FAT10 promoter, sequencing and methylation-specific sequencing of the promoter of FAT10 was performed. No mutations were found that could explain the differential expression of FAT10 between the tumor and non-tumorous tissues of HCC patients. However, six single nucleotide polymorphisms (SNPs), including one that has not been previously reported, were identified at the promoter of the FAT10 gene. Different haplotypes of these SNPs were found to significantly mediate different FAT10 promoter activities. Consistent with the experimental observation, differential FAT10 expression in the tumors of HCC patients carrying haplotype 1 was generally higher than those carrying haplotype II. Notably, the methylation status of this promoter was found to correlate with FAT10 expression levels. Hence, the aberrant overexpression of the FAT10 gene in the tumors of HCC patients is likely due to aberrant methylation, rather than mutations at the FAT10 promoter.

18.
Front Biosci ; 12: 234-45, 2007 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-17127296

RESUMEN

Hepatocellular carcinoma (HCC) is one of the world's leading fatal malignancies. Chronic infection with the hepatitis B virus (HBV) has been implicated with the development of HCC. For the past three decades, intensive research has focused on the role of HBV in hepatocarcinogenesis. Various HBV-associated models have emerged, but increasing evidence points to two major HBV-specific mechanisms that contribute to the development of HCC. The first is the integration of the viral genome into the host chromosome causing cis-effects, resulting in loss of tumor suppressor gene functions, and/or activation of tumor-promoting genes. The second mechanism involves the expression of trans-activating factors derived from the HBV genome, which have the potential to influence intracellular signal transduction pathways and alter host gene expression. A major player involved in this form of viral transactivation is the X protein (HBx). The HBx protein was found to display pleiotropic functions and has been implicated in the malignant transformation of chronically-infected liver cells. By disrupting cellular gene expression, viral products such as HBx may modulate cellular growth, repair and death, consequently resulting in the transformation of hepatocytes to an oncogenic state.


Asunto(s)
Carcinoma Hepatocelular/virología , Hepacivirus/patogenicidad , Hepatitis C Crónica/virología , Neoplasias Hepáticas/virología , Carcinoma Hepatocelular/genética , Transformación Celular Viral , Hepacivirus/genética , Humanos , Neoplasias Hepáticas/genética , Virus Oncogénicos/patogenicidad
19.
Oncogene ; 24(24): 3999-4008, 2005 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-15782120

RESUMEN

Cyr61 is a secreted, cysteine-rich, heparin-binding protein that mediates diverse functions including extracellular matrix formation, differentiation, cell proliferation, adhesion, migration, survival, as well as angiogenesis and tumorigenesis. In this study, we found that Cyr61 gene expression is significantly downregulated in the tumors of hepatocellular carcinoma (HCC) patients. To elucidate its mechanism of gene regulation, we examined the promoter of Cyr61 which contains two long stretches of repeats, each comprising d(CA) dinucleotide repeats downstream of HNF3beta- and ATF-binding sites. We hypothesized that the d(CA) repeats may play an important role in regulating Cyr61 promoter activity and performed promoter reporter assays to examine this. We found that a greater number of d(CA) repeats resulted in significantly lower promoter activity of the Cyr61 gene in the KB3-1 and HepG2 cell lines, but not in the MCF-7 cell line. In addition, the d(CA) repeats, but not other random sequences, were found to be important for Cyr61 promoter activity. We further demonstrate that the ATF- and HNF3beta-binding sites upstream the d(CA) repeats positively and negatively modulate Cyr61 promoter activity, respectively. An examination of the d(CA) dinucleotide patterns in the Cyr61 promoter in HCC patients revealed that approximately 32% of these patients exhibited either loss of heterozygosity or somatic mosaicism in either the tumors, adjacent normal liver tissues or both.


Asunto(s)
Carcinoma Hepatocelular/genética , Repeticiones de Dinucleótido/genética , Regulación Neoplásica de la Expresión Génica , Proteínas Inmediatas-Precoces/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Neoplasias Hepáticas/genética , Regiones Promotoras Genéticas , Inductores de la Angiogénesis , Secuencia de Bases , Sitios de Unión , Línea Celular Tumoral , Proteína 61 Rica en Cisteína , Genes Reporteros , Humanos , Datos de Secuencia Molecular , Valores de Referencia
20.
BMC Genomics ; 7: 111, 2006 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-16684361

RESUMEN

BACKGROUND: The MRP1 gene encodes the 190 kDa multidrug resistance-associated protein 1 (MRP1/ABCC1) and effluxes diverse drugs and xenobiotics. Sequence variations within this gene might account for differences in drug response in different individuals. To facilitate association studies of this gene with diseases and/or drug response, exons and flanking introns of MRP1 were screened for polymorphisms in 142 DNA samples from four different populations. RESULTS: Seventy-one polymorphisms, including 60 biallelic single nucleotide polymorphisms (SNPs), ten insertions/deletions (indel) and one short tandem repeat (STR) were identified. Thirty-four of these polymorphisms have not been previously reported. Interestingly, the STR polymorphism at the 5' untranslated region (5'UTR) occurs at high but different frequencies in the different populations. Frequencies of common polymorphisms in our populations were comparable to those of similar populations in HAPMAP or Perlegen. Nucleotide diversity indices indicated that the coding region of MRP1 may have undergone negative selection or recent population expansion. SNPs E10/1299 G>T (R433S) and E16/2012 G>T (G671V) which occur at low frequency in only one or two of four populations examined were predicted to be functionally deleterious and hence are likely to be under negative selection. CONCLUSION: Through in silico approaches, we identified two rare SNPs that are potentially negatively selected. These SNPs may be useful for studies associating this gene with rare events including adverse drug reactions.


Asunto(s)
Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Sistemas de Lectura Abierta/genética , Polimorfismo Genético/genética , Grupos de Población/genética , Selección Genética , Bases de Datos Genéticas , Exones/genética , Haplotipos , Humanos , Análisis de Secuencia de ADN , Expansión de Repetición de Trinucleótido/genética
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