Hepatocellular carcinoma in a mouse model fed a choline-deficient, L-amino acid-defined, high-fat diet

From NASH to HCC: current concepts and future challenges

Caloric excess and sedentary lifestyle have led to a global epidemic of obesity and metabolic syndrome. The hepatic consequence of metabolic syndrome and obesity, nonalcoholic fatty liver disease (NAFLD), is estimated to affect up to one-third of the adult population in many developed and developing countries. This spectrum of liver disease ranges from simple steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis. Owing to the high prevalence of NAFLD, especially in industrialized countries but also worldwide, and the consequent burden of progressive liver disease, there is mounting epidemiological evidence that NAFLD has rapidly become a leading aetiology underlying many cases of hepatocellular carcinoma (HCC). In this Review, we discuss NAFLD-associated HCC, including its epidemiology, the key features of the hepatic NAFLD microenvironment (for instance, adaptive and innate immune responses) that promote hepatocarcinogenesis and the management of HCC in patients with obesity and associated metabolic comorbidities. The challenges and future directions of research will also be discussed, including clinically relevant biomarkers for early detection, treatment stratification and monitoring as well as approaches to therapies for both prevention and treatment in those at risk or presenting with NAFLD-associated HCC.

18F-FDG PET/CT AS AN ASSESSMENT TOOL OF HEPATOCELLULAR CARCINOMA SECONDARY TO NON-ALCOHOLIC FATTY LIVER DISEASE DEVELOPMENT IN EXPERIMENTAL MODEL

BACKGROUND

Hepatocellular carcinoma (HCC) can be the last step of non-alcoholic fatty liver disease (NAFLD) evolution. Experimental models are crucial to elucidate the pathogenesis of HCC secondary to NAFLD. The 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) plays an important role in evaluating HCC development and progression.

OBJECTIVE

To standardize the imaging method of PET/CT with 18F-FDG as an evaluation tool of the experimental model of HCC secondary to NAFLD.

METHODS

Ten male Sprague-Dawley rats were fed with choline-deficient high-fat diet and diethylnitrosamine (DEN) in the drinking water for 16 weeks and then received 1 mL of saline solution (0.9%) daily by gavage for three weeks. At the 16th and 19th weeks, abdominal ultrasonography (USG) was performed. 18F-FDG PET/CT images were obtained before the beginning of experiment (week 0) and at the end (week 19). Histological and immunohistochemically analysis were also performed.

RESULTS

The USG results showed a homogeneous group at the 16th week with an average of 4.6±2.74 nodules per animal. At the 19th week, PET/CT findings demonstrated an average of 8.5±3.7 nodules per animal. The mean values of SUVmed and SUVmax were 2.186±0.1698 and 3.8±1.74, respectively. The average number of nodules per animal in the histological analysis was 5.5±1.5. From all nodules, 4.6% were classified as well-differentiated HCC and 81.8% were classified as poorly-differentiated HCC.

CONCLUSION

18F-FDG PET/CT was able to evaluate the development of HCC in an experimental model of NAFLD non-invasively. From the standardization of PET/CT in this model, it is possible to use this tool in future studies to monitor, in vivo and non-invasively, the progression of HCC.

Disease Progression and Pharmacological Intervention in a Nutrient-Deficient Rat Model of Nonalcoholic Steatohepatitis

BACKGROUND

There is a marked need for improved animal models of nonalcoholic steatohepatitis (NASH) to facilitate the development of more efficacious drug therapies for the disease.

METHODS

Here, we investigated the development of fibrotic NASH in male Wistar rats fed a choline-deficient L-amino acid-defined (CDAA) diet with or without cholesterol supplementation for subsequent assessment of drug treatment efficacy in NASH biopsy-confirmed rats. The metabolic profile and liver histopathology were evaluated after 4, 8, and 12 weeks of dieting. Subsequently, rats with biopsy-confirmed NASH were selected for pharmacological intervention with vehicle, elafibranor (30 mg/kg/day) or obeticholic acid (OCA, 30 mg/kg/day) for 5 weeks.

RESULTS

The CDAA diet led to marked hepatomegaly and fibrosis already after 4 weeks of feeding, with further progression of collagen deposition and fibrogenesis-associated gene expression during the 12-week feeding period. Cholesterol supplementation enhanced the stimulatory effect of CDAA on gene transcripts associated with fibrogenesis without significantly increasing collagen deposition. Pharmacological intervention with elafibranor, but not OCA, significantly reduced steatohepatitis scores, and fibrosis-associated gene expression, however, was unable to prevent progression in fibrosis scores.

CONCLUSION

CDAA-fed rats develop early-onset progressive NASH, which offers the opportunity to probe anti-NASH compounds with potential disease-modifying properties.

Pioglitazone Reduces Hepatocellular Carcinoma Development in Two Rodent Models of Cirrhosis

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the deadliest malignancies worldwide due to the lack of effective treatments. Chemoprevention in high-risk patients is a promising, alternative strategy. In this study, pioglitazone was investigated for its ability to prevent hepatocarcinogenesis in two rodent models of cirrhosis.

METHODS

In the first model, male Wistar rats were given repeated, low-dose injections of diethylnitrosamine (DEN) to accurately recapitulate the progression of fibrosis to cirrhosis and HCC. In the second model, a single dose of DEN was administered to male C57Bl/6 pups at day fifteen followed by administration of a choline-deficient, L-amino acid defined, high-fat diet (CDAHFD) at week six for 24 weeks. Pioglitazone treatment started at the first signs of fibrosis in both models.

RESULTS

Pioglitazone effectively reduced fibrosis progression and HCC development in both models. Gross tumor nodules were significantly reduced after pioglitazone treatment (7.4 ± 1.6 vs. 16.6 ± 2.6 in the rat DEN model and 5.86 ± 1.82 vs. 13.2 ± 1.25 in the mouse DEN+CDAHFD model). In both models, pioglitazone reduced the activation of mitogen-activated protein kinase (MAPK) and upregulated the hepato-protective AMP-activated protein kinase (AMPK) pathway via increasing circulating adiponectin production.

CONCLUSION

Pioglitazone is an effective agent for chemoprevention in rodents and could be repurposed as a multi-targeted drug for delaying liver fibrosis and hepatocarcinogenesis.

Trimethylamine N-oxide, a gut microbiota-dependent metabolite of choline, is positively associated with the risk of primary liver cancer: a case-control study

BACKGROUND

Evidence has suggested a potential link exists between trimethylamine-N-oxide (TMAO), a choline-derived metabolite produced by gut microbiota, and some cancers, but little is known for primary liver cancer (PLC).

METHODS

A case-control study was designed including 671 newly diagnosed PLC patients and 671 control subjects frequency-matched by age (±5 years) and sex, in Guangdong province, China. High-performance liquid chromatography with online electrospray ionization tandem mass spectrometry (HPLC-MS/MS) was used to measure serum TMAO and choline. The associations between these biomarkers and PLC risk were evaluated using logistic regression models.

RESULTS

Serum TMAO concentrations were greater in the PLC group than the control group (P = 0.002). Logistic regression analysis showed that the sex- and age-adjusted odds ratio (OR) and (95% confidence interval [CI]) was 3.43 (2.42-4.86) when comparing the top and bottom quartiles (Q4 vs Q1). After further adjusting for more selected confounders, the OR (95% CI) remained significant but was attenuated to 2.85 (1.59-5.11) (Q4 vs Q1). The multivariable-adjusted ORs (95% CIs) across quartiles of choline were 0.35-0.15 (P -trend < 0.001).

CONCLUSION

Higher serum levels of TMAO were associated with increased PLC risk. The association was stronger in those with lower serum levels of choline. Additional large prospective studies are required to confirm these findings.

TRIAL REGISTRATION

This study was registered at clinicaltrials.gov as NCT 03297255.

Animal models for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents ~90% of all cases of primary liver cancer and occurs predominantly in patients with underlying chronic liver disease and cirrhosis. Establishing appropriate animal models for HCC is required for basic and translational studies, especially the models that can recapitulate one of the human disease settings. Current animal models can be categorized as chemically-induced, genetically-engineered, xenograft, or a combination of these with each other or with a metabolic insult. A single approach to resemble human HCC in animals is not sufficient. Combining pathogenic insults in animal models may more realistically recapitulate the multiple etiologic agents occurring in humans. Combining chemical injury with metabolic disorder or alcohol consumption in mice reduces the time taken to hepatocarcinogenesis. Genetically-engineering weak activation of HCC-promoting pathways combined with disease-specific injury models will possibly mimic the pathophysiology of human HCC in distinct clinical settings.