Genome-wide analysis of copy number variation identifies candidate gene loci associated with the progression of non-alcoholic fatty liver disease

Genetic Polymorphisms and Diversity in Nonalcoholic Fatty Liver Disease (NAFLD): A Mini Review

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease with a wide spectrum of liver conditions ranging from hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The prevalence of NAFLD varies across populations, and different ethnicities have specific risks for the disease. NAFLD is a multi-factorial disease where the genetics, metabolic, and environmental factors interplay and modulate the disease's development and progression. Several genetic polymorphisms have been identified and are associated with the disease risk. This mini-review discussed the NAFLD's genetic polymorphisms and focusing on the differences in the findings between the populations (diversity), including of those reports that did not show any significant association. The challenges of genetic diversity are also summarized. Understanding the genetic contribution of NAFLD will allow for better diagnosis and management explicitly tailored for the various populations.

Update on genetics and epigenetics in metabolic associated fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is becoming the most frequent chronic liver disease worldwide. Metabolic (dysfunction) associated fatty liver disease (MAFLD) is suggested to replace the nomenclature of NAFLD. For individuals with metabolic dysfunction, multiple NAFLD-related factors also contribute to the development and progression of MAFLD including genetics and epigenetics. The application of genome-wide association study (GWAS) and exome-wide association study (EWAS) uncovers single-nucleotide polymorphisms (SNPs) in MAFLD. In addition to the classic SNPs in PNPLA3, TM6SF2, and GCKR, some new SNPs have been found recently to contribute to the pathogenesis of liver steatosis. Epigenetic factors involving DNA methylation, histone modifications, non-coding RNAs regulations, and RNA methylation also play a critical role in MAFLD. DNA methylation is the most reported epigenetic modification. Developing a non-invasion biomarker to distinguish metabolic steatohepatitis (MASH) or liver fibrosis is ongoing. In this review, we summarized and discussed the latest progress in genetic and epigenetic factors of NAFLD/MAFLD, in order to provide potential clues for MAFLD treatment.

Hepatocellular Carcinoma in Non-Alcoholic Fatty Liver Disease: From Epidemiology to Diagnostic Approach

Non-alcoholic fatty liver disease (NAFLD) is becoming the leading cause of liver morbidity worldwide and, as such, represents the pathogenic background for the increasing incidence of hepatocellular carcinoma (HCC). The annual incidence of NAFLD-related HCC is expected to increase by 45-130% by 2030. Diabetes mellitus is the most important risk factor for HCC development in NAFLD, with the risk further increased when associated with other metabolic traits, such as obesity, arterial hypertension and dyslipidemia. The highest risk of HCC exists in patients with advanced fibrosis or cirrhosis, although 20-50% of HCC cases arise in NAFLD patients with an absence of cirrhosis. This calls for further investigation of the pathogenic mechanisms that are involved in hepatocarcinogenesis, including genetics, metabolomics, the influence of the gut microbiota and immunological responses. Early identification of patients with or at risk of NAFLD is of utmost importance to improve outcomes. As NAFLD is highly prevalent in the community, the identification of cases should rely upon simple demographic and clinical characteristics. Once identified, these patients should then be evaluated for the presence of advanced fibrosis or cirrhosis and subsequently enter HCC surveillance programs if appropriate. A significant problem is the early recognition of non-cirrhotic NAFLD patients who will develop HCC, where new biomarkers and scores are potential solutions to tackle this issue.

Copy number variation and expression of exportin-4 associates with severity of fibrosis in metabolic associated fatty liver disease

Background

Liver fibrosis risk is a heritable trait, the outcome of which is the net deposition of extracellular matrix by hepatic stellate cell-derived myofibroblasts. Whereas nucleotide sequence variations have been extensively studied in liver fibrosis, the role of copy number variations (CNV) in which genes exist in abnormal numbers of copies (mostly due to duplication or deletion) has had limited exploration.

Methods

The impact of the XPO4 CNV on histological liver damage was examined in a cohort comprised 646 Caucasian patients with biopsy-proven MAFLD and 170 healthy controls. XPO4 expression was modulated and function was examined in human and animal models.

Findings

Here we demonstrate in a cohort of 816 subjects, 646 with biopsy-proven metabolic associated liver disease (MAFLD) and 170 controls, that duplication in the exportin 4 (XPO4) CNV is associated with the severity of liver fibrosis. Functionally, this occurs via reduced expression of hepatic XPO4 that maintains sustained activation of SMAD3/SMAD4 and promotes TGF-β1-mediated HSC activation and fibrosis. This effect was mediated through termination of nuclear SMAD3 signalling. XPO4 demonstrated preferential binding to SMAD3 compared to other SMADs and led to reduced SMAD3-mediated responses as shown by attenuation of TGFβ1 induced SMAD transcriptional activity, reductions in the recruitment of SMAD3 to target gene promoters following TGF-β1, as well as attenuation of SMAD3 phosphorylation and disturbed SMAD3/SMAD4 complex formation.

Interpretation

We conclude that a CNV in XPO4 is a critical mediator of fibrosis severity and can be exploited as a therapeutic target for liver fibrosis.

Funding

ME and JG are supported by the Robert W. Storr Bequest to the Sydney Medical Foundation, University of Sydney; a National Health and Medical Research Council of Australia (NHMRC) Program Grant (APP1053206) and Project and ideas grants (APP2001692, APP1107178 and APP1108422). AB is supported by an Australian Government Research Training Program (RTP) scholarship. EB is supported by Horizon 2020 under grant 634413 for the project EPoS.

Copy number variation in the CES1 gene and the risk of non-alcoholic fatty liver in a Chinese Han population

A recent genome-wide copy number variations (CNVs) scan identified a 16q12.2 deletion that included the carboxylesterase 1 (CES1) gene, which is important in the metabolism of fatty acids and cholesterol. We aimed to investigate whether CES1 CNVs was associated with susceptibility to non-alcoholic fatty liver disease (NAFLD) in a Chinese Han population. A case-control study was conducted among 303 patients diagnosed with NAFLD and 303 age (± 5) and sex-matched controls from the Affiliated Nanping First Hospital of Fujian Medical University in China. The copy numbers of CES1 were measured using TaqMan quantitative real-time polymerase chain reaction (qPCR) and serum CES1 was measured using enzyme-linked immunosorbent assays. The Chi-squared test and a logistic regression model were used to evaluate the association between CES1 CNVs and NAFLD susceptibility. The distribution of CES1 CNVs showed a higher frequency of CNVs loss (< 2) among patients; however, the difference was not significant (P = 0.05). After controlling for other known or suspected risk factors for NAFLD, CES1 CNVs loss was significantly associated with greater risk of NAFLD (adjusted OR = 2.75, 95% CI 1.30-5.85, P = 0.01); while CES1 CNVs gain (> 2) was not. There was a suggestion of an association between increased CES1 serum protein levels and CNVs losses among cases, although this was not statistically significant (P = 0.07). Copy number losses (< 2) of CES1 contribute to susceptibility to NAFLD in the Chinese Han population.

DNA copy number and structural variation (CNV) contributions to adult and childhood obesity

In recent years, obesity has reached epidemic proportions globally and has become a major public health concern. The development of obesity is likely caused by several behavioral, environmental, and genetic factors. Genomic variability among individuals is largely due to copy number variations (CNVs). Recent genome-wide association studies (GWAS) have successfully identified many loci containing CNV related to obesity. These obesity-related CNVs are informative to the diagnosis and treatment of genomic diseases. A more comprehensive classification of CNVs may provide the basis for determining how genomic diversity impacts the mechanisms of expression for obesity in children and adults of a variety of genders and ethnicities. In this review, we summarize current knowledge on the relationship between obesity and the CNV of several genomic regions, with an emphasis on genes at the following loci: 11q11, 1p21.1, 10q11.22, 10q26.3, 16q12.2, 16p12.3, and 4q25.

NAFLD-related HCC

Nonalcoholic fatty liver disease (NAFLD) is one of the major drivers for the rising trend in hepatocellular carcinoma (HCC). Over the past three decades, the incidence of both NAFLD and HCC have increased two- to threefold. It has been forecasted that the number of patients with NAFLD in the Unites States will reach 101 million by 2030; global increase is also foreseen. This trend will likely continue to translate into increased HCC in the Unites States and across the globe. In this chapter, we summarize the current evidence linking NAFLD, metabolic syndrome, particularly obesity and type 2 diabetes mellitus, and HCC. We describe the main molecular mechanisms connecting these metabolic perturbations and hepatocarcinogenesis.

Hepatocellular carcinoma in alcoholic and non-alcoholic fatty liver disease-one of a kind or two different enemies?

Hepatocellular cancer (HCC) is a cancer with an overall poor prognosis and an alarming globally rising incidence. While viral etiology of chronic liver disease and HCC is down-trending, alcohol and excess calorie intake have emerged as major culprits. Alcohol related liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) share similar pathogenetic mechanism of hepatic injury and in promoting development of HCC; yet some genetic and epigenetic features are distinct and may promise clinical utility. Population based intervention are urgently needed to reduce alcohol use and improve metabolic factors such as obesity and diabetes. The goal is to identify at-risk patients, to link these patients to care and to provide effective management of chronic liver disease and HCC. This review focuses on the epidemiology, pathophysiology including genetic and epigenetic altercation as well as clinical aspects of ALD and NAFLD associated HCC.

Molecular Pathogenesis of Nonalcoholic Steatohepatitis- (NASH-) Related Hepatocellular Carcinoma

The proportion of obese or diabetic population has been anticipated to increase in the upcoming decades, which rises the prevalence of nonalcoholic fatty liver disease (NAFLD) and its progression to nonalcoholic steatohepatitis (NASH). Recent evidence indicates that NASH is the main cause of chronic liver diseases and it is an important risk factor for development of hepatocellular carcinoma (HCC). Although the literature addressing NASH-HCC is growing rapidly, limited data is available about the etiology of NASH-related HCC. Experimental studies on the molecular mechanism of HCC development in NASH reveal that the carcinogenesis is relevant to complex changes in signaling pathways that mediate cell proliferation and energy metabolism. Genetic or epigenetic modifications and alterations in metabolic, immunologic, and endocrine pathways have been shown to be closely related to inflammation, liver injury, and fibrosis in NASH along with its subsequent progression to HCC. In this review, we provide an overview on the current knowledge of NASH-related HCC development and emphasize molecular signaling pathways regarding their mechanism of action in NASH-derived HCC.

Prediction of early-stage hepatocellular carcinoma using OncoScan chromosomal copy number aberration data

AIM

To identify chromosomal copy number aberrations (CNAs) in early-stage hepatocellular carcinoma (HCC) and analyze whether they are correlated with patient prognosis.

METHODS

One hundred and twenty patients with early-stage HCC were enrolled in our study, with the collection of formalin fixed, paraffin-embedded (FFPE) specimens and clinicopathological data. Tumor areas were marked by certified pathologists on a hematoxylin and eosin-stained slide, and cancer and adjacent non-cancerous tissues underwent extraction of DNA, which was analyzed with the Affymetrix OncoScan platform to assess CNAs and loss of heterozygosity (LOH). Ten individuals with nonmalignant disease were used as the control group. Another cohort consisting of 40 patients with stage I/II HCC were enrolled to analyze gene expression and to correlate findings with the OncoScan data.

RESULTS

Copy number amplifications occurred at chromosomes 1q21.1-q44 and 8q12.3-24.3 and deletions were found at 4q13.1-q35.2, 8p 23.2-21.1, 16q23.3-24.3, and 17p13.3-12, while LOH commonly occurred at 1p32.3, 3p21.31, 8p23.2-21.1, 16q22.1-24.3, and 17p 13.3-11 in early-stage HCC. Using Cox regression analysis, we also found that a higher percentage of genome change (≥ 60%) was an independent factor for worse prognosis in early-stage HCC (P = 0.031). Among the 875 genes in the OncoScan GeneChip, six were independent predictors of worse disease-free survival, of which three were amplified (MYC, ELAC2, and SYK) and three were deleted (GAK, MECOM, and WRN). Further, patients with HCC who exhibited ≥ 3 CNAs involving these six genes have worse outcomes compared to those who had < 3 CNAs (P < 0.001). Similarly, Asian patients with stage I HCC from The Cancer Genome Atlas harboring CNAs with these genes were also predicted to have poorer outcomes.

CONCLUSION

Patients with early-stage HCC and increased genome change or CNAs involving MYC, ELAC2, SYK, GAK, MECOM, or WRN are at risk for poorer outcome after resection.

Overactivation of intestinal sterol response element-binding protein 2 promotes diet-induced nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is characterized by lipid accumulation in the liver that may progress to hepatic fibrosis and nonalcoholic steatohepatitis (NASH). Mechanisms underlying NAFLD and NASH are not yet fully understood. Dietary cholesterol was recently shown to be a risk factor for the development of NASH, suggesting a role for intestinal handling of cholesterol. One important regulator of cholesterol homeostasis is the sterol response element-binding protein-2 (SREBP-2) transcription factor. We tested the hypothesis that the overactivation of intestinal SREBP-2 increases the susceptibility to diet-induced NASH. A transgenic mouse model with intestine-specific overexpression of active SREBP-2 (ISR2 mice) driven by villin promoter was used. ISR2 mice and their wild-type littermates were fed a regular chow diet or a high-fat, high-cholesterol (HFHC) diet (15% fat, 1% cholesterol) for 15 wk. Results showed that HFHC feeding to ISR2 mice caused hepatic inflammation with increased levels of proinflammatory cytokines. Histological examination demonstrated extensive fibrosis after a HFHC diet associated with a perivascular as well as pericellular collagen deposits in ISR2 mice compared with wild-type littermates. The severe hepatic inflammation and advanced fibrosis in ISR2 mice was not associated with a difference in lipid accumulation in ISR2 mice compared with wild type littermates after HFHC feeding. These data indicate that overactivation of intestinal SREBP2 promotes diet-induced hepatic inflammation with features of human NASH resulting in rapid severe fibrosis and provide a novel link between regulatory processes of intestinal cholesterol and progression of fatty liver.NEW & NOTEWORTHY The current study highlights the role of overactivation of intestinal SREBP-2 transcription factor in the progression of hepatic fibrosis associated with diet-induced NASH. Mice with intestine-specific overexpression of SREBP-2 demonstrated more inflammation and severe fibrosis in the liver in response to 15 wk of being fed a high-cholesterol, high-fat diet as compared with their wild-type littermates. These data demonstrate a novel link between intestinal regulatory processes of cholesterol metabolism and the pathogenesis of fatty liver diseases.

Acyl-CoA Thioesterase 1 (ACOT1) Regulates PPARα to Couple Fatty Acid Flux With Oxidative Capacity During Fasting

Hepatic acyl-CoA thioesterase 1 (ACOT1) catalyzes the conversion of acyl-CoAs to fatty acids (FAs) and CoA. We sought to determine the role of ACOT1 in hepatic lipid metabolism in C57Bl/6J male mice 1 week after adenovirus-mediated Acot1 knockdown. Acot1 knockdown reduced liver triglyceride (TG) as a result of enhanced TG hydrolysis and subsequent FA oxidation. In vitro experiments demonstrated that Acot1 knockdown led to greater TG turnover and FA oxidation, suggesting that ACOT1 is important for controlling the rate of FA oxidation. Despite increased FA oxidation, Acot1 knockdown reduced the expression of peroxisome proliferator-activated receptor α (PPARα) target genes, whereas overexpression increased PPARα reporter activity, suggesting ACOT1 regulates PPARα by producing FA ligands. Moreover, ACOT1 exhibited partial nuclear localization during fasting and cAMP/cAMP-dependent protein kinase signaling, suggesting local regulation of PPARα. As a consequence of increased FA oxidation and reduced PPARα activity, Acot1 knockdown enhanced hepatic oxidative stress and inflammation. The effects of Acot1 knockdown on PPARα activity, oxidative stress, and inflammation were rescued by supplementation with Wy-14643, a synthetic PPARα ligand. We demonstrate through these results that ACOT1 regulates fasting hepatic FA metabolism by balancing oxidative flux and capacity.

Type 2 diabetes mellitus and risk of hepatocellular carcinoma: spotlight on nonalcoholic fatty liver disease

The incidence of both type 2 diabetes mellitus (T2DM) and multiple cancer types are rapidly increasing worldwide. Several studies documented that T2DM is closely associated with an increased incidence of cancer. However, while some methodological considerations preclude a definitive association between T2DM and the risk of certain cancers, the relationship between T2DM and increased risk of incident hepatocellular carcinoma (HCC) remains significant even after adjustment for detection bias and reverse causation, indicating that such association is clinically reliable and robust. In addition, a number of observational studies also showed that T2DM is associated with higher mortality among persons with HCC. Some recent meta-analyses suggested that treatment with metformin may be associated with a lower risk of HCC, and may also beneficially influence HCC prognosis, whereas treatment with sulphonylureas or insulin seems to be related to a higher HCC risk. The underlying biological mechanisms linking T2DM and HCC are complex and difficult to elucidate, but the existence of close inter-connections among T2DM, obesity and nonalcoholic fatty liver disease (NAFLD) induces hepatic/systemic insulin resistance and causes the release of multiple pro-inflammatory cytokines, vasoactive factors and pro-oxidant molecules, which are all potentially implicated in the development and progression of HCC. In this clinical review, we discuss the epidemiological evidence linking T2DM to the risk of HCC. Moreover, we also briefly discuss the putative underlying mechanisms linking T2DM, NAFLD and HCC, and the potential effect of certain hypoglycemic agents on the risk of developing HCC.

Type 2 Diabetes and Hepatocellular Carcinoma: Risk Factors and Pathogenesis

PURPOSE OF REVIEW

This review aims to assess the epidemiological evidence for a link between type 2 diabetes and hepatocellular carcinoma and to investigate possible pathophysiological mechanisms.

RECENT FINDINGS

The presence of type 2 diabetes significantly increases the risk of developing hepatocellular carcinoma, and treatment with metformin may be associated with a lower risk. Treatment with insulin and sulphonylureas may be associated with increased risk. The pathophysiology underlying development of hepatocellular carcinoma in this context is complex and is likely to involve increased proinflammatory mediators, oxidative stress, JNK-1 activation, increased IGF-1 activity, altered gut microbiota and immunomodulation. Hepatocellular carcinoma incidence is increasing and this is likely to be linked to the increasing incidence of type 2 diabetes, obesity and the metabolic syndrome. These conditions increase the risk of developing hepatocellular carcinoma, and a greater understanding of the underlying pathophysiology may help with the development of novel treatments.

Phosphatidylethanolamine N-methyltransferase gene rs7946 polymorphism plays a role in risk of nonalcoholic fatty liver disease: evidence from meta-analysis

BACKGROUND

Phosphatidylethanolamine N-methyltransferase (PEMT) governs the secretion of hepatic triglycerides in the form of very low-density lipoprotein and has been implicated in nonalcoholic fatty liver disease (NAFLD). Studies on the role of the PEMT rs7946 polymorphism as a genetic modifier of NAFLD have reported inconsistent results. This meta-analysis was carried out to evaluate and summarize the association of PEMT rs7946 with susceptibility to NAFLD.

METHODS

A comprehensive literature search in Scopus, PubMed, Embase, Science Direct and Google Scholar was performed up to 31 August 2015, followed by data extraction and examination of summary estimates.

RESULTS

Six independent studies with a total of 792 NAFLD cases and 2722 controls fulfilled the inclusion criteria. Pooled results indicated that the rs7946 A-allele was associated significantly with an increased risk of NAFLD [odds ratio (OR) 1.55, 95% confidence interval (CI) 1.14-2.11, P=0.005]. A significant association was also found in alternative genetic models of inheritance: dominant, recessive and homozygote (OR 1.62, 95% CI 1.10-2.39, P=0.01; OR 1.42, 95% CI 1.12-1.81, P=0.003; and OR 1.64, 95% CI 1.18-2.29, P=0.004, respectively). Subgroup analysis by ethnicity indicated a significant association only in the East-Asians in the additive (OR=2.08, 95% CI 1.12-3.86, P=0.02), recessive (OR=2.94, 95% CI 1.60-5.37, P=0.0005) and homozygote (OR=1.86, 95% CI 1.15-3.01, P=0.01) models.

CONCLUSION

This study provides evidence of a significant association between the PEMT rs7946 A-allele and a risk of NAFLD, with the effect being more prominent in East-Asians, but not in non-Asians.

Nonalcoholic fatty liver disease and hepatocellular carcinoma

The fastest growing cause of cancer-related death is hepatocellular carcinoma (HCC), which is at least partly attributable to the rising prevalence of non-alcoholic fatty liver disease. Non-alcoholic fatty liver disease (NAFLD) encompasses a broad spectrum of conditions, ranging from non-progressive bland steatosis to malignant transformation into hepatocellular cancer. The estimated annual HCC incidence in the progressive form of NAFLD - non-alcoholic steatohepatitis (NASH) - is about 0.3%. The risk of HCC development is higher in men and increases with age, more advanced fibrosis, progressive obesity, insulin resistance and diabetes mellitus. Studies on the molecular mechanism of HCC development in NAFLD have shown that hepatocarcinogenesis is associated with complex changes at the immunometabolic interface. In line with these clinical risk factors, administration of a choline-deficient high-fat diet to mice over a prolonged period results in spontaneous HCC development in a high percentage of animals. The role of altered insulin signaling in tumorigenesis is further supported by the observation that components of the insulin-signaling cascade are frequently mutated in hepatocellular cancer cells. These changes further enhance insulin-mediated growth and cell division of hepatocytes. Furthermore, studies investigating nuclear factor kappa B (NF-κB) signaling and HCC development allowed dissection of the complex links between inflammation and carcinogenesis. To conclude, NAFLD reflects an important risk factor for HCC, develops also in non-cirrhotic livers and is a prototypic cancer involving inflammatory and metabolic pathways. STRENGTHS/WEAKNESSES AND SUMMARY OF THE TRANSLATIONAL POTENTIAL OF THE MESSAGES IN THE PAPER: The systematic review summarizes findings from unbiased clinical and translational studies on hepatocellular cancer in non-alcoholic fatty liver disease. This provides a concise overview on the epidemiology, risk factors and molecular pathogenesis of the NAFL-NASH-HCC sequence. One limitation in the field is that few HCC studies stratify patients by underlying etiology, although the etiology of the underlying liver disease is an important co-determinant of clinical disease course and molecular pathogenesis. Molecular profiling of NAFL and associated HCC holds great translational potential for individualized surveillance, prevention and therapy.

Development of an in vitro model to test antifibrotic drugs on primary human liver myofibroblasts

We have developed a culture model to assess antifibrotic drugs using normal human liver myofibroblasts (HLMFs) obtained from 31 subjects. Activation was evaluated in terms of α-smooth muscle actin (α-SMA) and collagen 1 (Coll1) expression using RT-PCR, and proliferation as the uptake of 5-ethynil-2'-deoxyuridine. Under analysis of variance, between-subject differences accounted for 70% of all variability and inter-experiment differences for 30%. The sensitivity of the model was determined by quantifying the effects in terms of relative expression, which were 0.74±0.03 for cyclosporine A (CsA) and 2.4±0.10 for transforming growth factor-beta (TGF-β) (P<0.0001 vs no treatment) for α-SMA expression. Inter-subject variations in α-SMA and Coll1 expression enabled the classification of subjects as potentially low or high fibrosers. Finally, we observed that pirfenidone (which has beneficial effects in vivo) significantly reduced the expressions of α-SMA and Coll1, whereas the angiotensin-converting enzyme inhibitor losartan (which has no effect in vivo) had no significant effect. Our model may thus detect the antifibrotic properties of drugs. Antifibrotic drugs with promising clinical relevance could possibly be selected using a bank of HLMFs from high fibrosers.

Genetic and epigenetic mechanisms of NASH

Along with the obesity epidemic, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased exponentially. The histological disease spectrum of NAFLD ranges from bland fatty liver (hepatic steatosis), to the concomitant presence of inflammation and ballooning which defines nonalcoholic steatohepatitis (NASH). The latter can progress in a subset to fibrosis, leading ultimately to cirrhosis and hepatocellular carcinoma. The past decade has seen tremendous advances in our understanding of the genetic and epigenetic bases of NAFLD, mainly through the application of high end technology platforms including genome-wide association studies (GWAS). These have helped to define common gene variants (minor allele frequency >5 %) that contribute to the NAFLD phenotype. Looking to the future, these discoveries are expected to lead to improved diagnostics, the personalization of medicine, and a better understanding of the pathophysiological underpinnings that drive the transition from NAFLD to steatohepatitis and fibrosis, leading to the identification of novel therapeutic targets. In this review, we summarize data on the current state of knowledge with regard to the genetic and epigenetic mechanisms for the development of NASH.

Copy number variation in exportin-4 (XPO4) gene and its association with histological severity of non-alcoholic fatty liver disease

A recent genome-wide copy number (CNV) scan identified a 13q12.11 duplication in the exportin-4 (XPO4) gene to be associated with non-alcoholic steatohepatitis (NASH). We sought to confirm the finding in a larger cohort and to assess the serum XPO4 pattern in a broad spectrum of non-alcoholic fatty liver disease (NAFLD) cases. We analysed 249 NAFLD patients and 232 matched controls using TaqMan assay and serum XPO4 was measured. Copy number distribution was as follows: copy number neutral (NAFLD: 53.8%, controls: 68.6%), copy number losses (NAFLD: 13.3%, controls: 12.9%), copy number gains (NAFLD: 32.9%, controls: 18.5%). CNV gain was significantly associated with a greater risk of NAFLD (adjusted OR 2.22, 95% CI 1.42–3.46, P = 0.0004) and NASH (adjusted OR 2.33, 95% CI 1.47–3.68, P = 0.0003). Interestingly, subjects carrying extra copy number showed significantly higher serum ALT and triglyceride (P < 0.05). Serum XPO4 levels progressively declined (P = 0.043) from controls (24.6 ng/mL) to simple steatosis (20.8 ng/mL) to NASH (13.8 ng/mL). In conclusion, XPO4 CNV duplication was associated with histological severity of NAFLD, and accompanied by changes in serum XPO4 levels providing insights into NAFLD pathogenesis, and has the potential for biomarker development.

Steatohepatitic variant of hepatocellular carcinoma in the absence of metabolic syndrome or background steatosis: a clinical, pathological, and genetic study

Association between the steatohepatitic hepatocellular carcinoma (SH-HCC) and metabolic syndrome has been suggested. Most SH-HCC morphology appears to result from a typical HCC that retains the ability to respond to the metabolic syndrome and develops features of steatohepatitis. We aim to ask if this is true for all SH-HCC cases, or does the SH-HCC morphology in some cases reflect genetic changes inherent to the HCC itself, as opposed to wide tissue response in liver to the metabolic syndrome. Twelve SH-HCC cases occurring in individuals without metabolic syndrome were identified and examined pathologically. Genomic microarray analysis was performed in a subset. The SH-HCC in all cases showed diffuse moderate to marked fatty change, abundant balloon cells often containing Mallory-Denk bodies, and pericellular fibrosis. The background livers showed no significant fatty change in any cases. The background livers showed cirrhosis in seven cases and had no fibrosis in five cases. The underlying liver diseases were hepatitis C (n = 4) and no known (n = 8). The clinical and pathological characteristics of these cases did not differ significantly from the cases with the classical HCC morphology. Loss of 9q12-q31.1 was observed in a subset of cases, a finding that has not been previously reported in HCC. Our results indicate HCC can also develop steatohepatitic morphology outside the setting of fatty liver disease or metabolic syndrome. This SH-HCC is more likely to result from genetic changes to shared genes or metabolic pathways within the tumor and is an ideal subtype for future genetic studies. In this regard, potential genetic alterations include loss of 9q12-q31.1.

Multidisciplinary perspective of hepatocellular carcinoma: A Pacific Northwest experience

Hepatocellular carcinoma (HCC) is the most rapidly increasing type of cancer in the United States. HCC is a highly malignant cancer, accounting for at least 14000 deaths in the United States annually, and it ranks third as a cause of cancer mortality in men. One major difficulty is that most patients with HCC are diagnosed when the disease is already at an advanced stage, and the cancer cannot be surgically removed. Furthermore, because almost all patients have cirrhosis, neither chemotherapy nor major resections are well tolerated. Clearly there is need of a multidisciplinary approach for the management of HCC. For example, there is a need for better understanding of the fundamental etiologic mechanisms that are involved in hepatocarcinogenesis, which could lead to the development of successful preventive and therapeutic modalities. It is also essential to define the cellular and molecular bases for malignant transformation of hepatocytes. Such knowledge would: (1) greatly facilitate the identification of patients at risk; (2) prompt efforts to decrease risk factors; and (3) improve surveillance and early diagnosis through diagnostic imaging modalities. Possible benefits extend also to the clinical management of this disease. Because there are many factors involved in pathogenesis of HCC, this paper reviews a multidisciplinary perspective of recent advances in basic and clinical understanding of HCC that include: molecular hepatocarcinogenesis, non-invasive diagnostics modalities, diagnostic pathology, surgical modality, transplantation, local therapy and oncological/target therapeutics.

Chemokine ligand 2 and paraoxonase-1 in non-alcoholic fatty liver disease: The search for alternative causative factors

The incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) is constantly increasing. Despite this is apparently associated with the growing increase in obesity, insulin resistance and obesity-related metabolic disturbances their presence is not a necessary or sufficient condition to explain the accumulation of fat in the liver. Conversely, NAFLD is a predictor of other metabolic risks. NAFLD is currently the most frequent chronic liver disease but should not be considered benign or anecdotic because a considerable proportion of patients with NAFLD progress to cirrhosis and end-stage liver disease. Consequently, the search for alternative molecular mechanisms with therapeutic implications in NAFLD and associated disorders deserves a careful consideration. Mitochondria are possible targets as these organelles generate energy from nutrient oxidation. Some findings, generated in patients with extreme obesity and in murine models, support the notion that NAFLD could be a mitochondrial disease. This is plausible because mitochondrial dysfunction affects the accumulation of lipids in hepatocytes and promotes lipid peroxidation, the production of reactive oxygen species, the release of cytokines causing inflammation and cell death. Here we discuss basic research and mechanistic studies targeting the role of chemokine ligand 2 in liver inflammation and that of the paraoxonases in the oxidative stress. Their combination and association with mitochondrial dysfunction may uncover mechanisms underlying the progression of NAFLD and may help to identify novel therapeutic targets.

Non-alcoholic fatty liver disease in patients with diabetes mellitus

Non-alcoholic fatty liver disease (NAFLD), including the disease stages steatosis and non-alcoholic steatohepatitis, is the most common cause of chronic liver disease worldwide and linked to the epidemic of diabetes mellitus and obesity. It is characterized by a high cardiovascular and liver-related mortality and expected to be the leading cause for liver transplantation in the near future. This review summarizes recent progress made in our understanding of the disease pathogenesis and the clinical management of patients with NAFLD. Strategies to manage diabetes mellitus will be evaluated in terms of their effectiveness in treating patients with NAFLD and novel pharmacological targets capable to treat diabetes mellitus and NAFLD will be highlighted.

DNA markers in molecular diagnostics for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the one of the leading causes of cancer mortality in the world, mainly due to the difficulty of early detection and limited therapeutic options. The implementation of HCC surveillance programs in well-defined, high-risk populations were only able to detect about 40-50% of HCC at curative stages (Barcelona Clinic Liver Cancer stages 0 & 1) due to the low sensitivities of the current screening methods. The advance of sequencing technologies has identified numerous modifications as potential candidate DNA markers for diagnosis/surveillance. Here we aim to provide an overview of the DNA alterations that result in activation of cancer pathways known to potentially drive HCC carcinogenesis and to summarize performance characteristics of each DNA marker in the periphery (blood or urine) for HCC screening.