1 1134 137 COMPREHENSIVE GENETIC AND EPIGENETIC ANALYSIS OF OCCULT HEPATITIS B FROM LIVER TISSUE SAMPLES. BACKGROUND: OCCULT INFECTION WITH HEPATITIS B VIRUS (HBV) IS A TYPE OF CHRONIC HBV INFECTION THAT IS CHARACTERIZED BY THE ABSENCE OF A DETECTABLE HEPATITIS B SURFACE ANTIGEN IN THE BLOOD AND BY VERY LOW LEVELS OF HBV DNA IN THE BLOOD AND LIVER. THE MECHANISMS LEADING TO OCCULT HBV INFECTION REMAIN POORLY UNDERSTOOD BUT INCLUDE POSSIBLE GENETIC MUTATIONS AND DELETIONS. RECENTLY, IT HAS BEEN SHOWN THAT HBV HAS CPG ISLANDS THAT ARE METHYLATED, RAISING THE POSSIBILITY THAT EPIGENETIC CHANGES MAY ALSO BE IMPORTANT. METHODS: THE FULL-LENGTH GENOMES OF ISOLATES FROM 5 CASES OF OCCULT HBV INFECTION WERE CLONED AND ANALYZED FOR MUTATIONS AND DELETIONS. ADDITIONAL STUDIES WERE PERFORMED TO EXAMINE FOR APOBEC3G (1 MEMBER OF A FAMILY OF DEAMINATING PROTEINS THAT ARE PART OF THE INNATE IMMUNE SYSTEM'S DEFENSE AGAINST VIRAL INFECTION) HYPEREDITING AND METHYLATION OF VIRAL DNA. RESULTS: NUMEROUS MUTATIONS AND DELETIONS WERE FOUND IN THE GENOMES OF OCCULT HBV. HOWEVER, SIMILAR TYPES AND LOCATIONS OF POLYMORPHISMS WERE ALSO NOTED IN THE GENOME SEQUENCES OF HBV ISOLATED FROM CONTROL LIVER TISSUE SAMPLES OBTAINED FROM INDIVIDUALS WITH NONOCCULT HBV INFECTION. EVIDENCE OF APOBEC3G HYPEREDITING WAS FOUND IN 1 CASE OF OCCULT HBV INFECTION, BUT HYPEREDITED SEQUENCES MADE UP ONLY A SMALL PROPORTION OF THE VIRAL SEQUENCES. METHYLATION OF HBV CPG ISLANDS 1 AND 2 WAS EVIDENT IN BOTH OCCULT AND NONOCCULT HBV SEQUENCES, WITH ISLAND 2 MORE DENSELY METHYLATED IN OCCULT HBV SEQUENCES AND ISLAND 1 MORE DENSELY METHYLATED IN NONOCCULT HBV SEQUENCES. CONCLUSION: DELETIONS AND MUTATIONS ARE COMMON IN OCCULT HBV BUT ARE ALSO FOUND IN CONTROL NONOCCULT HBV, AND NO UNIQUE GENETIC SIGNATURE FOR OCCULT HBV WAS FOUND. METHYLATION PATTERNS DIFFER BETWEEN CASES OF OCCULT AND NONOCCULT HBV INFECTION, SUGGESTING THAT EPIGENETIC CHANGES MAY BE RELEVANT TO OCCULT HBV. TOGETHER, THESE FINDINGS SUGGEST THAT MULTIPLE MECHANISMS CAN CONTRIBUTE TO OCCULT HBV INFECTION. 2008 2 6862 40 [OCCULT HEPATITIS B VIRUS INFECTION]. OCCULT HEPATITIS B VIRUS (HBV) INFECTION IS A PECULIAR FORM OF CHRONIC VIRAL INFECTION IDENTIFIED SINCE THE EARLY 80'S AND CAN BE DEFINED AS THE PRESENCE OF HBV DNA IN THE SERUM AND/OR IN THE LIVER TISSUE OF PATIENTS NEGATIVE FOR THE HBV SURFACE ANTIGEN (HBSAG) USING USUAL SEROLOGICAL TESTS. THE DATA ABOUT THE PREVALENCE OF OCCULT HBV INFECTION ARE CONTRASTING AND THE REPORTED PREVALENCES IN VARIOUS CATEGORIES OF INDIVIDUALS ARE HIGHLY DIVERSE. THE MOLECULAR BASIS OF THE OCCULT HBV INFECTION IS THE COVALENTLY CLOSED-CIRCULAR DNA (CCCDNA) THAT PERSISTS IN THE CELL NUCLEI AND THAT SERVES AS A TEMPLATE FOR GENE TRANSCRIPTION. THE PHYSIOPATHOLOGY OF OCCULT HBV INFECTION IS STILL UNCLEAR. HOWEVER, THE AVAILABLE DATA SUGGEST THAT THE HOST'S IMMUNE RESPONSE, THE CO-INFECTIONS WITH OTHER INFECTIOUS AGENTS AND EPIGENETIC FACTORS MAY PLAY IMPORTANT ROLES IN INDICING THE OCCULT STATUS. THE CLINICAL RELEVANCE OF OCCULTHBVINFECTION REMAINS DEBATED BUT IT MAY IMPACT IN FOUR CLINICAL CONTEXTS: 1) THE TRANSMISSION OF THE INFECTION BY BLOOD TRANSFUSION OR ORGAN TRANSPLANTATION; 2) THE ACUTE REACTIVATION WHEN AN IMMUNOSUPPRESSIVE STATUS OCCURS MAINLY IN PATIENTS WITH ISOLATED ANTI-HBC (CHEMOTHERAPY, TRANSPLANTATIONS, IMMUNODEPRESSION, NEW IMMUNOSUPPRESSIVE THERAPY AS ANTI-CD20 OR ANTI TNF); 3) THE POTENT BUT NON PROVED PROGRESSION OF LIVER FIBROSIS IN HCV INFECTED PATIENTS OR IN PATIENTS WITH CRYPTOGENETIC LIVER DISEASE; AND, 4. THE RISK FACTOR FOR HEPATOCELLULAR CARCINOMA DEVELOPMENT. 2008 3 4817 40 OCCULT HEPATITIS B VIRUS INFECTION: AN UPDATE. OCCULT HEPATITIS B VIRUS (HBV) INFECTION (OBI) REFERS TO A CONDITION IN WHICH REPLICATION-COMPETENT VIRAL DNA IS PRESENT IN THE LIVER (WITH DETECTABLE OR UNDETECTABLE HBV DNA IN THE SERUM) OF INDIVIDUALS TESTING NEGATIVE FOR THE HBV SURFACE ANTIGEN (HBSAG). IN THIS PECULIAR PHASE OF HBV INFECTION, THE COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IS IN A LOW STATE OF REPLICATION. MANY ADVANCES HAVE BEEN MADE IN CLARIFYING THE MECHANISMS INVOLVED IN SUCH A SUPPRESSION OF VIRAL ACTIVITY, WHICH SEEMS TO BE MAINLY RELATED TO THE HOST'S IMMUNE CONTROL AND EPIGENETIC FACTORS. OBI IS DIFFUSED WORLDWIDE, BUT ITS PREVALENCE IS HIGHLY VARIABLE AMONG PATIENT POPULATIONS. THIS DEPENDS ON DIFFERENT GEOGRAPHIC AREAS, RISK FACTORS FOR PARENTERAL INFECTIONS, AND ASSAYS USED FOR HBSAG AND HBV DNA DETECTION. OBI HAS AN IMPACT IN SEVERAL CLINICAL CONTEXTS: (A) IT CAN BE TRANSMITTED, CAUSING A CLASSIC FORM OF HEPATITIS B, THROUGH BLOOD TRANSFUSION OR LIVER TRANSPLANTATION; (B) IT MAY REACTIVATE IN THE CASE OF IMMUNOSUPPRESSION, LEADING TO THE POSSIBLE DEVELOPMENT OF EVEN FULMINANT HEPATITIS; (C) IT MAY ACCELERATE THE PROGRESSION OF CHRONIC LIVER DISEASE DUE TO DIFFERENT CAUSES TOWARD CIRRHOSIS; (D) IT MAINTAINS THE PRO-ONCOGENIC PROPERTIES OF THE "OVERT" INFECTION, FAVORING THE DEVELOPMENT OF HEPATOCELLULAR CARCINOMA. 2022 4 4816 36 OCCULT HEPATITIS B VIRUS INFECTION: A COMPLEX ENTITY WITH RELEVANT CLINICAL IMPLICATIONS. OCCULT HEPATITIS B VIRUS (HBV) INFECTION IS A WORLD-WIDE ENTITY, FOLLOWING THE GEOGRAPHICAL DISTRIBUTION OF DETECTABLE HEPATITIS B. THIS ENTITY IS DEFINED AS THE PERSISTENCE OF VIRAL GENOMES IN THE LIVER TISSUE AND IN SOME INSTANCES ALSO IN THE SERUM, ASSOCIATED TO NEGATIVE HBV SURFACE ANTIGEN SEROLOGY. THE MOLECULAR BASIS OF THE OCCULT INFECTION IS RELATED TO THE LIFE CYCLE OF HBV, WHICH PRODUCES A COVALENTLY CLOSED CIRCULAR DNA THAT PERSISTS IN THE CELL NUCLEI AS AN EPISOME, AND SERVES AS A TEMPLATE FOR GENE TRANSCRIPTION. THE MECHANISM RESPONSIBLE FOR THE HBSAG NEGATIVE STATUS IN OCCULT HBV CARRIERS IS A STRONG SUPPRESSION OF VIRAL REPLICATION, PROBABLY DUE TO THE HOST'S IMMUNE RESPONSE, CO-INFECTION WITH OTHER INFECTIOUS AGENTS AND EPIGENETIC FACTORS. THERE IS EMERGING EVIDENCE OF THE POTENTIAL CLINICAL RELEVANCE OF OCCULT HBV INFECTION, SINCE THIS COULD BE INVOLVED IN OCCULT HBV TRANSMISSION THROUGH ORTHOTOPIC LIVER TRANSPLANT AND BLOOD TRANSFUSION, REACTIVATION OF HBV INFECTION DURING IMMUNOSUPPRESSION, IMPAIRING CHRONIC LIVER DISEASE OUTCOME AND ACTING AS A RISK FACTOR FOR HEPATOCELLULAR CARCINOMA. THEREFORE IT IS IMPORTANT TO BEAR IN MIND THIS ENTITY IN CRYPTOGENETIC LIVER DISEASES, HEPATITIS C VIRUS/HIV INFECTED PATIENTS AND IMMUNOSUPRESSED INDIVIDUALS. IT IS ALSO NECESSARY TO INCREASE OUR KNOWLEDGE IN THIS FASCINATING FIELD TO DEFINE BETTER STRATEGIES TO DIAGNOSE AND TREAT THIS INFECTION. 2011 5 6707 36 VIRAL HEPATITIS AND HEPATOCELLULAR CARCINOMA: STATE OF THE ART. VIRAL HEPATITIS IS ONE OF THE MAIN CAUSES LEADING TO HEPATOCELLULAR CARCINOMA (HCC). THE CONTINUED RISE IN INCIDENCE OF HCC SUGGESTS ADDITIONAL FACTORS FOLLOWING INFECTION MAY BE INVOLVED. THIS REVIEW EXAMINES RECENT STUDIES INVESTIGATING THE MOLECULAR MECHANISMS OF CHRONIC HEPATITIS AND ITS ASSOCIATION WITH HEPATOCARCINOGENESIS. HEPATITIS B VIRUS PATIENTS WITH GENOTYPE C DISPLAY AN AGGRESSIVE DISEASE COURSE LEADING TO HCC MORE THAN OTHER GENOTYPES. FURTHERMORE, HEPATITIS B EXCRETORY ANTIGEN (HBEAG) SEEMS TO BE A MORE SENSITIVE PREDICTIVE TUMOR MARKER EXHIBITING A SIX-FOLD HIGHER RELATIVE RISK IN PATIENTS WITH POSITIVE HBSAG AND HBEAG THAN THOSE WITH HBSAG ONLY. SINGLE OR COMBINED MUTATIONS OF VIRAL GENOME CAN PREDICT HCC DEVELOPMENT IN UP TO 80% OF PATIENTS. SEVERAL MUTATIONS IN HBX-GENE ARE RELATED WITH HIGHER HCC INCIDENCE. OVEREXPRESSION OF THE CORE PROTEIN IN HCV LEADS TO HEPATOCELLULAR LIPID ACCUMULATION ASSOCIATED WITH ONCOGENESIS. REDUCED NUMBER AND DECREASED FUNCTIONALITY OF NATURAL KILLER CELLS IN CHRONIC HCV INDIVIDUALS DYSREGULATE THEIR SURVEILLANCE FUNCTION IN TUMOR AND VIRAL CELLS RESULTING IN HCC. FURTHERMORE, HIGH T-CELL IMMUNOGLOBULIN AND MUCIN 3 LEVELS SUPRESS CD8+ T-CELLS, WHICH LEAD TO IMMUNOLOGICAL DYSREGULATION. HEPATITIS D PROMOTES HCC DEVELOPMENT INDIRECTLY VIA MODIFICATIONS TO INNATE IMMUNITY, EPIGENETIC ALTERATIONS AND PRODUCTION OF REACTIVE OXYGEN SPECIES WITH THE LHDAG BEING THE MOST HIGHLY ASSOCIATED WITH HCC DEVELOPMENT. SUMMARIZING THE RESULTS, HBV AND HCV INFECTION REPRESENT THE MOST ASSOCIATED FORMS OF VIRAL HEPATITIS CAUSING HCC. FURTHER STUDIES ARE WARRANTED TO FURTHER IMPROVE THE PREDICTION OF HIGH-RISK PATIENTS AND DEVELOPMENT OF TARGETED THERAPEUTICS PREVENTING THE TRANSITION FROM HEPATIC INFLAMMATION-FIBROSIS TO CANCER. 2021 6 3248 45 HEPATITIS B VIRUS GENOME ASYMMETRY IN HEPATOCELLULAR CARCINOMA. BACKGROUND: THE ASSOCIATION BETWEEN HEPATITIS B VIRUS (HBV) MUTATIONS AND HEPATOCARCINOGENESIS WERE REPORTED IN THE LITERATURE. PREFERENCE FOR G OVER C IN THE LEADING DNA STRAND HAS BEEN REPORTED TO ACCOUNT FOR THE ASYMMETRY IN NUCLEOTIDE (NT) COMPOSITION. THE AIM OF THIS STUDY WAS TO ANALYZE THE COMPLETE GENOME SEQUENCE AND COMPOSITIONAL ASYMMETRY OF HBV IN DIFFERENT STAGES OF HEPATITIS B. METHODS: FULL GENOME SEQUENCING OF 24 PATIENTS WITH CHRONIC HEPATITIS B, SOME OF WHOM ALSO HAD CIRRHOSIS AND HEPATOCELLULAR CARCINOMA (HCC) WAS PERFORMED. MUTATIONS ANALYSIS WAS IMPLEMENTED IN A COMPARISON WITH A HBV GENOTYPE D REFERENCE FROM AN INTERNATIONAL DNA DATABASE. CPGPROD, A WEB-BASED APPLICATION, WAS USED TO EVALUATE CG CONTENT AND PREDICT CPG ISLANDS. RESULTS: ALL STRAINS WERE 3182 BASE PAIRS (BP) IN LENGTH, EXCEPT FOR TWO CASES OF HCC IN WHICH 9 AND 21 NT, RESPECTIVELY, WERE DELETED IN PRES2. THE GENETIC RELATEDNESS OF THESE ISOLATES WAS 97%-100%. THERE WERE COMMON CPG-RICH REGIONS IN ALL 24 ISOLATED FULL GENOME SEQUENCES, HOWEVER A STRONG NEGATIVE GC SKEW FOR FORMING A CPG ISLAND IN THE MINUS STRAND WERE EXHIBITED IN OVERLAP WITH ENHANCER I IN THREE HCC PATIENTS, A CIRRHOTIC PATIENT AND THREE WITH CHRONIC HEPATITIS. CONCLUSION: THE HIGH PERCENTAGE OF SEQUENCE IDENTITY BETWEEN HBV ISOLATES IN OUR PATIENTS DEMONSTRATES THAT GENOMIC FACTORS, EXCEPT FOR GENOTYPE, ARE INVOLVED IN HEPATOCARCINOGENESIS. VARIATIONS IN GC CONTENT WHICH WERE CAUSED BY A DIFFERENT SPECTRUM OF MUTATIONS MAY AFFECT DNA COMPOSITIONAL ASYMMETRY AND EPIGENETIC MODIFICATION OF HBV DNA IN HCC. 2012 7 4056 44 MAPPING THE HETEROGENEITY OF HISTONE MODIFICATIONS ON HEPATITIS B VIRUS DNA USING LIVER NEEDLE BIOPSIES OBTAINED FROM CHRONICALLY INFECTED PATIENTS. COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) FORMS THE BASIS FOR REPLICATION AND PERSISTENCE OF HEPATITIS B VIRUS (HBV) IN THE CHRONICALLY INFECTED LIVER. WE HAVE PREVIOUSLY SHOWN THAT VIRAL TRANSCRIPTION IS SUBJECT TO REGULATION BY POSTTRANSLATIONAL MODIFICATIONS (PTMS) OF HISTONE PROTEINS BOUND TO CCCDNA THROUGH ANALYSIS OF DE NOVO HBV-INFECTED CELL LINES. WE NOW REPORT THE SUCCESSFUL ADAPTATION OF THIS CHROMATIN IMMUNOPRECIPITATION SEQUENCING (CHIPSEQ) APPROACH FOR ANALYSIS OF FINE-NEEDLE PATIENT LIVER BIOPSY SPECIMENS TO INVESTIGATE THE ROLE OF HISTONE PTMS IN CHRONICALLY HBV-INFECTED PATIENTS. USING 18 SPECIMENS FROM PATIENTS IN DIFFERENT STAGES OF CHRONIC HBV INFECTION, OUR WORK SHOWS THAT THE PROFILE OF HISTONE PTMS IN CHRONIC INFECTION IS MORE NUANCED THAN PREVIOUSLY OBSERVED IN IN VITRO MODELS OF ACUTE INFECTION. IN LINE WITH OUR PREVIOUS FINDINGS, WE FIND THAT THE MAJORITY OF HBV-DERIVED SEQUENCES ARE ASSOCIATED WITH THE ACTIVATING HISTONE PTM H3K4ME3. HOWEVER, WE SHOW A STRIKING INTERPATIENT VARIABILITY OF ITS DEPOSITION IN THIS PATIENT COHORT CORRELATED WITH VIRAL TRANSCRIPTION AND PATIENT HBV EARLY ANTIGEN (HBEAG) STATUS. UNEXPECTEDLY, WE DETECTED DEPOSITION OF THE CLASSICAL INHIBITORY HISTONE PTM H3K9ME3 ON HBV-DNA IN AROUND HALF OF THE PATIENT BIOPSY SPECIMENS, WHICH COULD NOT BE LINKED TO REDUCED LEVELS OF VIRAL TRANSCRIPTS. OUR RESULTS SHOW THAT CURRENT IN VITRO MODELS ARE UNABLE TO FULLY RECAPITULATE THE COMPLEX EPIGENETIC LANDSCAPE OF CHRONIC HBV INFECTION OBSERVED IN VIVO AND DEMONSTRATE THAT FINE-NEEDLE LIVER BIOPSY SPECIMENS CAN PROVIDE SUFFICIENT MATERIAL TO FURTHER INVESTIGATE THE INTERACTION OF VIRAL AND HOST PROTEINS ON HBV-DNA.IMPORTANCE HEPATITIS B VIRUS (HBV) IS A MAJOR GLOBAL HEALTH CONCERN, CHRONICALLY INFECTING MILLIONS OF PATIENTS AND CONTRIBUTING TO A RISING BURDEN OF LIVER DISEASE. THE VIRAL GENOME FORMS THE BASIS FOR CHRONIC INFECTION AND HAS BEEN SHOWN TO BE SUBJECT TO REGULATION BY EPIGENETIC MECHANISMS, SUCH AS POSTTRANSLATIONAL MODIFICATION OF HISTONE PROTEINS. HERE, WE CONFIRM AND EXPAND ON PREVIOUS RESULTS BY ADAPTING A HIGH-RESOLUTION TECHNIQUE FOR ANALYSIS OF HISTONE MODIFICATIONS FOR USE WITH PATIENT-DERIVED FINE-NEEDLE LIVER BIOPSY SPECIMENS. OUR WORK HIGHLIGHTS THAT THE SITUATION IN VIVO IS MORE COMPLEX THAN PREDICTED BY CURRENT IN VITRO MODELS, FOR EXAMPLE, BY SUGGESTING A NOVEL, NONCANONICAL ROLE OF THE HISTONE MODIFICATION H3K9ME3 IN THE HBV LIFE CYCLE. IMPORTANTLY, ENABLING THE USE OF FINE-NEEDLE LIVER BIOPSY SPECIMENS FOR SUCH HIGH-RESOLUTION ANALYSES MAY FACILITATE FURTHER RESEARCH INTO THE EPIGENETIC REGULATION OF THE HBV GENOME. 2019 8 6337 25 THE ROLE OF DNA-METHYLTRANSFERASES IN THE LIFE CYCLE OF HEPATITIS B VIRUS AND PATHOGENESIS OF CHRONIC HEPATITIS B. CHRONIC HEPATITIS B IS CAUSED BY A PERSISTENT FORM OF HEPATITIS B VIRUS, COVALENTLY CLOSED CIRCULAR DNA (CCCDNA). STABILITY OF CCCDNA IS ASSOCIATED WITH INTRACELLULAR LOCALIZATION OF CCCDNA AND FORMATION OF MINICHROMOSOME, REGULATED BY EPIGENETIC MECHANISMS. ONE OF THE KEY MECHANISMS IN EPIGENETICS IS METHYLATION OF DNA ON CPG ISLANDS. EXPRESSION LEVELS OF DNA-METHYLTRANSFERASES (DNMTS) IN CHRONIC HEPATITIS B PATIENTS WERE SHOWN TO BE UPREGULATED. NEVERTHELESS, THE ROLE OF DNMTS IN THE LIFE CYCLE OF HBV AND THEIR EFFECTS ON THE CELL REMAIN ELUSIVE. IN THIS REVIEW, WE DISCUSS LATEST ACHIEVEMENTS ON THE ROLE OF DNMTS IN CHRONIC HEPATITIS B AND HBV IN VITRO MODELS. 2018 9 6115 30 THE EPIGENETIC CONTROL OF HEPATITIS B VIRUS MODULATES THE OUTCOME OF INFECTION. EPIGENETIC MODIFICATIONS ARE STABLE ALTERATIONS IN GENE EXPRESSION THAT DO NOT INVOLVE MUTATIONS OF THE GENETIC SEQUENCE ITSELF. IT HAS BECOME INCREASINGLY CLEAR THAT EPIGENETIC FACTORS CONTRIBUTE TO THE OUTCOME OF CHRONIC HEPATITIS B VIRUS (HBV) INFECTION BY AFFECTING CELLULAR AND VIRION GENE EXPRESSION, VIRAL REPLICATION AND THE DEVELOPMENT OF HEPATOCELLULAR CARCINOMA. HBV PERSISTS IN THE NUCLEUS OF INFECTED HEPATOCYTES AS A STABLE NON-INTEGRATED COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) WHICH FUNCTIONS AS A MINICHROMOSOME. THERE ARE TWO MAJOR FORMS OF HBV EPIGENETIC REGULATION: POSTTRANSLATIONAL MODIFICATION OF HISTONE PROTEINS ASSOCIATED WITH THE CCCDNA MINICHROMOSOME AND DNA METHYLATION OF VIRAL AND HOST GENOMES. THIS REVIEW EXPLORES HOW HBV CAN INTERPHASE WITH HOST EPIGENETIC REGULATION IN ORDER TO EVADE HOST DEFENCES AND TO PROMOTE ITS OWN SURVIVAL AND PERSISTENCE. WE FOCUS ON THE EFFECT OF CCCDNA BOUND-HISTONE MODIFICATIONS AND THE METHYLATION STATUS OF HBV DNA IN REGULATING VIRAL REPLICATION. INVESTIGATION OF HBV EPIGENETIC CONTROL HAS IMPORTANT CLINICAL CORRELATES WITH REGARDS TO THE DEVELOPMENT OF POTENTIAL THERAPEUTIC REGIMENS THAT WILL SUCCESSFULLY ERADICATE HBV INFECTION AND DEAL WITH HBV REACTIVATION IN THOSE UNDERGOING TREATMENT WITH DEMETHYLATING AGENTS. 2015 10 4449 42 MOLECULAR MECHANISM OF HEPATITIS B VIRUS-INDUCED HEPATOCARCINOGENESIS. HEPATITIS B VIRUS (HBV) INFECTION IS A GLOBAL PUBLIC HEALTH PROBLEM WITH APPROXIMATELY 2 BILLION PEOPLE THAT HAVE BEEN EXPOSED TO THE VIRUS. HBV IS A MEMBER OF A FAMILY OF SMALL, ENVELOPED DNA VIRUSES CALLED HEPADNAVIRUSES, AND HAS A PREFERENTIAL TROPISM FOR HEPATOCYTES OF MAMMALS AND BIRDS. EPIDEMIOLOGICAL STUDIES HAVE PROVED A STRONG CORRELATION BETWEEN CHRONIC HEPATITIS B VIRUS INFECTION AND THE DEVELOPMENT OF HEPATOCELLULAR CARCINOMA (HCC). HCC IS THE FIFTH MOST COMMON MALIGNANCY WITH ABOUT 700000 NEW CASES EACH YEAR, AND MORE THAN 50% OF THEM ARISE IN HBV CARRIERS. A LARGE NUMBER OF STUDIES DESCRIBE THE WAY IN WHICH HBV CAN CONTRIBUTE TO HCC DEVELOPMENT. MULTIPLE MECHANISMS HAVE BEEN PROPOSED, INCLUDING THE ACCUMULATION OF GENETIC DAMAGE DUE TO IMMUNE-MEDIATED HEPATIC INFLAMMATION AND THE INDUCTION OF OXIDATIVE STRESS. THERE IS EVIDENCE OF THE DIRECT EFFECTS OF THE VIRAL PROTEINS HBX AND HBS ON THE CELL BIOLOGY. INTEGRATION OF HBV-DNA INTO THE HUMAN GENOME IS CONSIDERED AN EARLY EVENT IN THE CARCINOGENIC PROCESS AND CAN INDUCE, THROUGH INSERTIONAL MUTAGENESIS, THE ALTERATION OF GENE EXPRESSION AND CHROMOSOMAL INSTABILITY. HBV HAS ALSO EPIGENETIC EFFECTS THROUGH THE MODIFICATION OF THE GENOMIC METHYLATION STATUS. FURTHERMORE, THE VIRUS PLAYS AN IMPORTANT ROLE IN THE REGULATION OF MICRORNA EXPRESSION. THIS REVIEW WILL SUMMARIZE THE MANY MECHANISMS INVOLVED IN HBV-RELATED LIVER CARCINOGENESIS. 2014 11 4815 42 OCCULT HEPATITIS B INFECTION AND HEPATOCELLULAR CARCINOMA: EPIDEMIOLOGY, VIROLOGY, HEPATOCARCINOGENESIS AND CLINICAL SIGNIFICANCE. OCCULT HEPATITIS B INFECTION (OBI) REFERS TO A CONDITION WHERE REPLICATION-COMPETENT HBV DNA IS PRESENT IN THE LIVER, WITH OR WITHOUT HBV DNA IN THE BLOOD, IN INDIVIDUALS WITH SERUM HBSAG NEGATIVITY ASSESSED BY CURRENTLY AVAILABLE ASSAYS. THE EPISOMAL COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IN OBI IS IN A LOW REPLICATIVE STATE. VIRAL GENE EXPRESSION IS MEDIATED BY EPIGENETIC CONTROL OF HBV TRANSCRIPTION, INCLUDING THE HBV CPG ISLAND METHYLATION PATHWAY AND POST-TRANSLATIONAL MODIFICATION OF CCCDNA-BOUND HISTONE, WITH A DIFFERENT PATTERN FROM PATIENTS WITH CHRONIC HBV INFECTION. THE PREVALENCE OF OBI VARIES TREMENDOUSLY ACROSS PATIENT POPULATIONS OWING TO NUMEROUS FACTORS, SUCH AS GEOGRAPHIC LOCATION, ASSAY CHARACTERISTICS, HOST IMMUNE RESPONSE, COINFECTION WITH OTHER VIRUSES, AND VACCINATION STATUS. APART FROM THE RISK OF VIRAL REACTIVATION UPON IMMUNOSUPPRESSION AND THE RISK OF TRANSMISSION OF HBV, OBI HAS BEEN IMPLICATED IN HEPATOCELLULAR CARCINOMA (HCC) DEVELOPMENT IN PATIENTS WITH CHRONIC HCV INFECTION, THOSE WITH CRYPTOGENIC OR KNOWN LIVER DISEASE, AND IN PATIENTS WITH HBSAG SEROCLEARANCE AFTER CHRONIC HBV INFECTION. AN INCREASING NUMBER OF PROSPECTIVE STUDIES AND META-ANALYSES HAVE REPORTED A HIGHER INCIDENCE OF HCC IN PATIENTS WITH HCV AND OBI, AS WELL AS MORE ADVANCED TUMOUR HISTOLOGICAL GRADES AND EARLIER AGE OF HCC DIAGNOSIS, COMPARED WITH PATIENTS WITHOUT OBI. THE PROPOSED PATHOGENETIC MECHANISMS OF OBI-RELATED HCC INCLUDE THE INFLUENCE OF HBV DNA INTEGRATION ON THE HEPATOCYTE CELL CYCLE, THE PRODUCTION OF PRO-ONCOGENIC PROTEINS (HBX PROTEIN AND MUTATED SURFACE PROTEINS), AND PERSISTENT LOW-GRADE NECROINFLAMMATION (CONTRIBUTING TO THE DEVELOPMENT OF FIBROSIS AND CIRRHOSIS). THERE REMAIN UNCERTAINTIES ABOUT EXACTLY HOW, AND IN WHAT ORDER, THESE MECHANISMS DRIVE THE DEVELOPMENT OF TUMOURS IN PATIENTS WITH OBI. 2020 12 6016 34 THE ASSOCIATION BETWEEN HEPATOCARCINOGENESIS AND INTRACELLULAR ALTERATIONS DUE TO HEPATITIS B VIRUS INFECTION. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION IS A WORLDWIDE HEALTH PROBLEM LEADING TO SEVERE LIVER DYSFUNCTION, INCLUDING LIVER CIRRHOSIS AND HEPATOCELLULAR CARCINOMA. ALTHOUGH CURRENT ANTIVIRAL THERAPIES FOR CHRONIC HBV INFECTION HAVE BEEN IMPROVED AND CAN LEAD TO A STRONG SUPPRESSION OF VIRAL REPLICATION, IT IS DIFFICULT TO COMPLETELY ELIMINATE THE VIRUS WITH THESE THERAPIES ONCE CHRONIC HBV INFECTION IS ESTABLISHED IN THE HOST. FURTHERMORE, CHRONIC HBV INFECTION ALTERS INTRACELLULAR METABOLISM AND SIGNALLING PATHWAYS, RESULTING IN THE ACTIVATION OF CARCINOGENESIS IN THE LIVER. HBV PRODUCES FOUR VIRAL PROTEINS: HEPATITIS B SURFACE-, HEPATITIS B CORE-, HEPATITIS B X PROTEIN, AND POLYMERASE; EACH PLAYS AN IMPORTANT ROLE IN HBV REPLICATION AND THE INTRACELLULAR SIGNALLING PATHWAYS ASSOCIATED WITH HEPATOCARCINOGENESIS. IN VITRO AND IN VIVO EXPERIMENTAL MODELS FOR ANALYZING HBV INFECTION AND REPLICATION HAVE BEEN ESTABLISHED, AND GENE EXPRESSION ANALYSES USING MICROARRAYS OR NEXT-GENERATION SEQUENCING HAVE ALSO BEEN DEVELOPED. THUS, IT IS POSSIBLE TO CLARIFY THE MOLECULAR MECHANISMS FOR INTRACELLULAR ALTERATIONS, SUCH AS ENDOPLASMIC RETICULUM STRESS, OXIDATIVE STRESS, AND EPIGENETIC MODIFICATIONS. IN THIS REVIEW, THE IMPACT OF HBV VIRAL PROTEINS AND INTRACELLULAR ALTERATIONS IN HBV-ASSOCIATED HEPATOCARCINOGENESIS ARE DISCUSSED. 2021 13 3392 27 HOST AND VIRAL GENETIC VARIATION IN HBV-RELATED HEPATOCELLULAR CARCINOMA. HEPATOCELLULAR CARCINOMA (HCC) IS THE FIFTH MOST COMMON CANCER IN MEN AND THE SECOND LEADING CAUSE OF CANCER DEATHS GLOBALLY. THE HIGH PREVALENCE OF HCC IS DUE IN PART TO THE HIGH PREVALENCE OF CHRONIC HBV INFECTION AND THE HIGH MORTALITY RATE IS DUE TO THE LACK OF BIOMARKERS FOR EARLY DETECTION AND LIMITED TREATMENT OPTIONS FOR LATE STAGE HCC. THE OBSERVED INDIVIDUAL VARIANCE IN DEVELOPMENT OF HCC IS ATTRIBUTABLE TO DIFFERENCES IN HBV GENOTYPE AND MUTATIONS, HOST PREDISPOSING GERMLINE GENETIC VARIATIONS, THE ACQUISITION OF TUMOR-SPECIFIC SOMATIC MUTATIONS, AS WELL AS ENVIRONMENTAL FACTORS. HBV GENOTYPE C AND MUTATIONS IN THE PRES, BASIC CORE PROMOTER (BCP) OR HBX REGIONS ARE ASSOCIATED WITH AN INCREASED RISK OF HCC. GENOME-WIDE ASSOCIATION STUDIES HAVE IDENTIFIED COMMON POLYMORPHISMS IN KIF1B, HLA-DQ, STAT4, AND GRIK1 WITH ALTERED RISK OF HBV-RELATED HCC. HBV INTEGRATION INTO GROWTH CONTROL GENES (SUCH AS TERT), PRO-ONCOGENIC GENES, OR TUMOR SUPPRESSOR GENES AND THE ONCOGENIC ACTIVITY OF TRUNCATED HBX PROMOTE HEPATOCARCINOGENESIS. SOMATIC MUTATIONS IN THE TERT PROMOTER AND CLASSIC CANCER SIGNALING PATHWAYS, INCLUDING WNT (CTNNB1), CELL CYCLE REGULATION (TP53), AND EPIGENETIC MODIFICATION (ARID2 AND MLL4) ARE FREQUENTLY DETECTED IN HEPATIC TUMOR TISSUES. THE IDENTIFICATION OF HBV AND HOST VARIATION ASSOCIATED WITH TUMOR INITIATION AND PROGRESSION HAS CLINICAL UTILITY FOR IMPROVING EARLY DIAGNOSIS AND PROGNOSIS; WHEREAS THE IDENTIFICATION OF SOMATIC MUTATIONS DRIVING TUMORIGENESIS HOLD PROMISE TO INFORM PRECISION TREATMENT FOR HCC PATIENTS. 2018 14 4920 29 PARALLEL EPIGENETIC AND GENETIC CHANGES IN THE PATHOGENESIS OF HEPATITIS VIRUS-ASSOCIATED HEPATOCELLULAR CARCINOMA. HEPATOCELLULAR CARCINOMA (HCC) IS ONE OF THE MOST FREQUENT TUMOR TYPES IN THE WORLD, WITH SHORT SURVIVAL TIMES AND FEW TREATMENT OPTIONS. HEPATITIS B VIRUS (HBV) AND HEPATITIS C VIRUS (HCV) ARE MAJOR ETIOLOGIC AGENTS OF HCC, ALTHOUGH THE ASSOCIATED MECHANISMS ARE INCOMPLETELY UNDERSTOOD. THE AVAILABLE EVIDENCE SUGGESTS THAT BOTH VIRUSES PROMOTE TUMORIGENESIS BY UP-REGULATING GENES THAT PROMOTE HEPATOCELLULAR GROWTH AND SURVIVAL, AND BY DOWN-REGULATING OTHER GENES THAT ACT AS TUMOR SUPPRESSORS AND NEGATIVE GROWTH REGULATORY MOLECULES. SIGNIFICANTLY, A NUMBER OF THE PATHWAYS THAT ARE ALTERED BY THESE VIRUSES ARE THE SAME ONES THAT ACCUMULATE GENETIC ALTERATIONS DURING TUMOR PROGRESSION. THIS SUGGESTS THAT THE PATHWAYS THAT PROMOTE VIRUS PERSISTENCE AND REPLICATION MAY ALSO PROMOTE CELL GROWTH AND SURVIVAL. FROM THE PERSPECTIVE OF THE VIRUS, THIS PROMOTES CHRONIC INFECTION, WHILE FROM THE PERSPECTIVE OF THE HOST, THIS PROMOTES TUMORIGENESIS. 2006 15 42 45 A COMPREHENSIVE GENOME-WIDE PROFILING COMPARISON BETWEEN HBV AND HCV INFECTED HEPATOCELLULAR CARCINOMA. BACKGROUND: HEPATOCELLULAR CARCINOMA (HCC) IS ONE OF THE MOST COMMON CANCERS WORLDWIDE, ESPECIALLY IN EAST ASIA. EVEN WITH THE PROGRESS IN THERAPY, 5-YEAR SURVIVAL RATES REMAIN UNSATISFIED. CHRONIC INFECTION WITH THE HEPATITIS B VIRUS (HBV) OR HEPATITIS C VIRUS (HCV) HAS BEEN EPIDEMIOLOGICALLY ASSOCIATED WITH HCC AND IS THE MAJOR ETIOLOGY IN THE EAST ASIAN POPULATION. THE DETAILED MECHANISM, ESPECIALLY THE CHANGES OF DNA METHYLATION AND GENE EXPRESSION BETWEEN THE TWO TYPES OF VIRUS-RELATED HCC, AND THEIR CONTRIBUTIONS TO THE HCC DEVELOPMENT, METASTASIS, AND RECURRENCE REMAIN LARGELY UNKNOWN. METHODS: IN THIS INTEGRATED ANALYSIS, WE CHARACTERIZED GENOME-SCALE PROFILES OF HBV AND HCV INFECTED HCC BY COMPARING THEIR GENE EXPRESSION PATTERN, METHYLATION PROFILES, AND COPY NUMBER VARIATIONS FROM THE PUBLICLY ACCESSIBLE DATA OF THE CANCER GENOME ATLAS PROGRAM (TCGA). RESULTS: THE HLA-A, STAT1, AND OAS2 GENES WERE HIGHLY ENRICHED AND UP-REGULATED DISCOVERED IN THE HCV-INFECTED HCC. HYPOMETHYLATION BUT NOT COPY NUMBER VARIATIONS MIGHT BE THE MAJOR FACTOR FOR THE UP-REGULATION OF THESE IMMUNE-RELATED GENES IN HCV-INFECTED HCC. CONCLUSIONS: THE RESULTS INDICATED THE DIFFERENT EPIGENETIC CHANGES OF HBV/HCV RELATED HEPATOCARCINOGENESIS. THE TOP UP-REGULATED GENES IN HCV GROUP WERE SIGNIFICANTLY CLUSTERED IN THE IMMUNE-RELATED AND DEFENSE RESPONSE PATHWAYS. THESE FINDINGS WILL HELP US TO UNDERSTAND THE PATHOGENESIS OF HBV/HCV ASSOCIATED HEPATOCELLULAR CARCINOMA. 2019 16 3567 36 IMPACT OF HEPATITIS VIRUS AND AGING ON DNA METHYLATION IN HUMAN HEPATOCARCINOGENESIS. HEPATOCELLULAR CARCINOMA (HCC) USUALLY DEVELOPS ON THE BASIS OF CHRONIC HEPATITIS AND LIVER CIRRHOSIS, WHERE INACTIVATION OF SEVERAL TUMOR SUPPRESSOR GENES (TSGS) TAKES PLACE VIA METHYLATION OF THE PROMOTER. INTERESTINGLY, THESE METHYLATION EVENTS ARE MORE PREVALENT IN A BACKGROUND LIVER AT HIGH RISK OF HCC THAN ONE AT LOW RISK. ABNORMAL METHYLATION IS ALSO OBSERVED IN PRECANCEROUS NODULES SUCH AS DYSPLASTIC NODULES AND ADENOMAS, SUGGESTING THAT EPIGENETIC ALTERATION IS AN EARLY EVENT FOR HCC CARCINOGENESIS. IT IS POSSIBLE THAT INFECTION WITH THE HEPATITIS VIRUS INDUCES ALTERATION OF METHYLATION AT PROMOTERS OF TSGS. SOME STUDIES SUGGESTED THAT VIRAL PROTEINS INTERFERE WITH DNA METHYLTRANSFERASE IN CHRONIC HEPATITIS B. INDUCTION OF EPIGENETIC ALTERATION IN CHRONIC HEPATITIS C MIGHT, HOWEVER, MIGHT BE A CONSEQUENCE OF OXIDATIVE STRESS. IN ADDITION, WE PROPOSED AGE SHOULD BE TAKEN INTO CONSIDERATION FOR HCC DEVELOPMENT VIA EPIGENETIC PATHWAYS. FURTHER INVESTIGATIONS ARE REQUIRED TO UNDERSTAND THE MECHANISM OF INDUCING EPIGENETIC INSTABILITY DURING HEPATOCARCINOGENESIS. 2010 17 2980 38 GENETIC BASIS OF HEPATITIS VIRUS-ASSOCIATED HEPATOCELLULAR CARCINOMA: LINKAGE BETWEEN INFECTION, INFLAMMATION, AND TUMORIGENESIS. HEPATITIS VIRUS INFECTION IS A LEADING CAUSE OF CHRONIC LIVER DISEASE, INCLUDING CIRRHOSIS AND HEPATOCELLULAR CARCINOMA (HCC). ALTHOUGH ANTI-VIRAL THERAPIES AGAINST HEPATITIS B VIRUS (HBV) AND HEPATITIS C VIRUS (HCV) HAVE DRAMATICALLY PROGRESSED DURING THE PAST DECADE, THE ESTIMATED NUMBER OF PEOPLE CHRONICALLY INFECTED WITH HBV AND/OR HCV IS ~370 MILLION, AND HEPATITIS VIRUS-ASSOCIATED HEPATOCARCINOGENESIS IS A SERIOUS HEALTH CONCERN WORLDWIDE. UNDERSTANDING THE MECHANISM OF VIRUS-ASSOCIATED CARCINOGENESIS IS CRUCIAL TOWARD BOTH TREATMENT AND PREVENTION, AND THE RECENTLY DEVELOPED WHOLE GENOME/EXOME SEQUENCING ANALYSIS USING NEXT-GENERATION SEQUENCING TECHNOLOGIES HAS CONTRIBUTED TO UNVEILING THE LANDSCAPE OF GENETIC AND EPIGENETIC ABERRATIONS IN NOT ONLY TUMOR TISSUES BUT ALSO THE BACKGROUND LIVER TISSUES UNDERLYING CHRONIC LIVER DAMAGE CAUSED BY HEPATITIS VIRUS INFECTION. SEVERAL MAJOR MECHANISMS UNDERLIE THE GENETIC AND EPIGENETIC ABERRATIONS IN THE HEPATITIS VIRUS-INFECTED LIVER, SUCH AS THE GENERATION OF REACTIVE OXIDATIVE STRESS, ECTOPIC EXPRESSION OF DNA MUTATOR ENZYMES, AND DYSFUNCTION OF THE DNA REPAIR SYSTEM. IN ADDITION, DIRECT ONCOGENIC EFFECTS OF HEPATITIS VIRUS, REPRESENTED BY THE INTEGRATION OF HBV-DNA, ARE OBSERVED IN INFECTED HEPATOCYTES. ELUCIDATING THE WHOLE PICTURE OF GENETIC AND EPIGENETIC ALTERATIONS, AS WELL AS THE MECHANISMS OF TUMORIGENESIS, WILL FACILITATE THE DEVELOPMENT OF EFFICIENT TREATMENT AND PREVENTION STRATEGIES FOR HEPATITIS VIRUS-ASSOCIATED HCC. 2017 18 3186 39 HBV COVALENTLY CLOSED CIRCULAR DNA MINICHROMOSOMES IN DISTINCT EPIGENETIC TRANSCRIPTIONAL STATES DIFFER IN THEIR VULNERABILITY TO DAMAGE. BACKGROUND AND AIMS: HBV COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) IS A MAJOR OBSTACLE FOR A CURE OF CHRONIC HEPATITIS B. ACCUMULATING EVIDENCE SUGGESTS THAT EPIGENETIC MODIFICATIONS REGULATE THE TRANSCRIPTIONAL ACTIVITY OF CCCDNA MINICHROMOSOMES. HOWEVER, IT REMAINS UNCLEAR HOW THE EPIGENETIC STATE OF CCCDNA AFFECTS ITS STABILITY. APPROACHES AND RESULTS: BY USING HBV INFECTION CELL MODELS AND IN VITRO AND IN VIVO RECOMBINANT CCCDNA (RCCCDNA) AND HBVCIRCLE MODELS, THE REDUCTION RATE OF HBV CCCDNA AND THE EFFICACY OF APOLIPOPROTEIN B MRNA EDITING ENZYME CATALYTIC SUBUNIT 3A (APOBEC3A)-MEDIATED AND CRISPR/CRISPR-ASSOCIATED 9 (CAS9)-MEDIATED CCCDNA TARGETING WERE COMPARED BETWEEN CCCDNAS WITH DISTINCT TRANSCRIPTIONAL ACTIVITIES. INTERFERON-ALPHA TREATMENT AND HEPATITIS B X PROTEIN (HBX) DELETION WERE APPLIED AS TWO STRATEGIES FOR CCCDNA REPRESSION. CHROMATIN IMMUNOPRECIPITATION AND MICROCOCCAL NUCLEASE ASSAYS WERE PERFORMED TO DETERMINE THE EPIGENETIC PATTERN OF CCCDNA. HBV CCCDNA LEVELS REMAINED STABLE IN NONDIVIDING HEPATOCYTES; HOWEVER, THEY WERE SIGNIFICANTLY REDUCED DURING CELL DIVISION, AND THE REDUCTION RATE WAS SIMILAR BETWEEN CCCDNAS IN TRANSCRIPTIONALLY ACTIVE AND TRANSCRIPTIONALLY REPRESSED STATES. STRIKINGLY, HBV RCCCDNA WITHOUT HBX EXPRESSION EXHIBITED A SIGNIFICANTLY LONGER PERSISTENCE IN MICE. THE CCCDNA WITH LOW TRANSCRIPTIONAL ACTIVITY EXHIBITED AN EPIGENETICALLY INACTIVE PATTERN AND WAS MORE DIFFICULT TO ACCESS BY APOBEC3A AND ENGINEERED CRISPR-CAS9. THE EPIGENETIC REGULATOR ACTIVATING CCCDNA INCREASED ITS VULNERABILITY TO APOBEC3A. CONCLUSIONS: HBV CCCDNA MINICHROMOSOMES IN DISTINCT EPIGENETIC TRANSCRIPTIONAL STATES SHOWED A SIMILAR REDUCTION RATE DURING CELL DIVISION BUT SIGNIFICANTLY DIFFERED IN THEIR ACCESSIBILITY AND VULNERABILITY TO TARGETED NUCLEASES AND ANTIVIRAL AGENTS. EPIGENETIC SENSITIZATION OF CCCDNA MAKES IT MORE SUSCEPTIBLE TO DAMAGE AND MAY POTENTIALLY CONTRIBUTE TO AN HBV CURE. 2022 19 2939 30 GENETIC AND EPIGENETIC ALTERATIONS IN HEPATITIS B VIRUS-ASSOCIATED HEPATOCELLULAR CARCINOMA. HEPATITIS B VIRUS (HBV) IS A MAJOR CAUSE OF HEPATOCELLULAR CARCINOMA (HCC). ITS CHRONIC INFECTION CAN LEAD TO CHRONIC LIVER INFLAMMATION AND THE ACCUMULATION OF GENETIC ALTERATIONS TO RESULT IN THE ONCOGENIC TRANSFORMATION OF HEPATOCYTES. HBV CAN ALSO SENSITIZE HEPATOCYTES TO ONCOGENIC TRANSFORMATION BY CAUSING GENETIC AND EPIGENETIC CHANGES OF THE HOST CHROMOSOMES. HBV DNA CAN INSERT INTO HOST CHROMOSOMES AND RECENT LARGE-SCALE WHOLE-GENOME SEQUENCING STUDIES REVEALED RECURRENT HBV DNA INTEGRATIONS SITES THAT MAY PLAY IMPORTANT ROLES IN THE INITIATION OF HEPATOCELLULAR CARCINOGENESIS. HBV CAN ALSO CAUSE EPIGENETIC CHANGES BY ALTERING THE METHYLATION STATUS OF CELLULAR DNA, THE POST-TRANSLATIONAL MODIFICATION OF HISTONES, AND THE EXPRESSION OF MICRORNAS. THESE CHANGES CAN ALSO LEAD TO THE EVENTUAL HEPATOCELLULAR TRANSFORMATION. THESE RECENT FINDINGS ON THE GENETIC AND EPIGENETIC ALTERATIONS OF THE HOST CHROMOSOMES INDUCED BY HBV OPENED A NEW AVENUE FOR THE DEVELOPMENT OF NOVEL DIAGNOSIS AND TREATMENTS FOR HBV-INDUCED HCC. 2015 20 3255 26 HEPATITIS B VIRUS X PROTEIN MEDIATED EPIGENETIC ALTERATIONS IN THE PATHOGENESIS OF HEPATOCELLULAR CARCINOMA. CHRONIC HEPATITIS B VIRUS (HBV) INFECTION IS A WORLDWIDE HEALTH PROBLEM. HEPATITIS B VIRUS X PROTEIN (HBX), A PLEIOTROPIC REGULATORY PROTEIN ENCODED BY HBV, IS NECESSARY FOR THE TRANSCRIPTION OF HBV COVALENTLY CLOSED CIRCULAR DNA (CCCDNA) MINICHROMOSOMES, AND AFFECTS THE EPIGENETIC REGULATION OF HOST CELLS. THE EPIGENETIC REPROGRAMMING OF HBX ON HOST CELL GENOME IS STRONGLY INVOLVED IN HBV-RELATED HCC CARCINOGENESIS. HERE, WE REVIEW THE LATEST FINDINGS OF THE EPIGENETIC REGULATION INDUCED BY HBX PROTEIN IN HEPATOCELLULAR CARCINOMA (HCC), INCLUDING DNA METHYLATION, HISTONE MODIFICATION AND NON-CODING RNA EXPRESSION. THE INFLUENCE OF HBX ON THE EPIGENETIC REGULATION OF CCCDNA IS ALSO SUMMARIZED. IN ADDITION, PRELIMINARY STUDIES OF TARGETED DRUGS FOR EPIGENETIC CHANGES INDUCED BY HBX ARE ALSO DISCUSSED. THE EXPLORATION OF EPIGENETIC MARKERS AS POTENTIAL TARGETS WILL HELP TO DEVELOP NEW PREVENTION AND/OR TREATMENT METHODS FOR HBX-RELATED HCC. 2022