Direct effect of branched-chain amino acids on the growth and metabolism of cultured human hepatocellular carcinoma cells

Recent Insights into the Biomarkers, Molecular Targets and Mechanisms of Non-Alcoholic Steatohepatitis-Driven Hepatocarcinogenesis

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (NASH) are chronic hepatic conditions leading to hepatocellular carcinoma (HCC) development. According to the recent "multiple-parallel-hits hypothesis", NASH could be caused by abnormal metabolism, accumulation of lipids, mitochondrial dysfunction, and oxidative and endoplasmic reticulum stresses and is found in obese and non-obese patients. Recent translational research studies have discovered new proteins and signaling pathways that are involved not only in the development of NAFLD but also in its progression to NASH, cirrhosis, and HCC. Nevertheless, the mechanisms of HCC developing from precancerous lesions have not yet been fully elucidated. Now, it is of particular importance to start research focusing on the discovery of novel molecular pathways that mediate alterations in glucose and lipid metabolism, which leads to the development of liver steatosis. The role of mTOR signaling in NASH progression to HCC has recently attracted attention. The goals of this review are (1) to highlight recent research on novel genetic and protein contributions to NAFLD/NASH; (2) to investigate how recent scientific findings might outline the process that causes NASH-associated HCC; and (3) to explore the reliable biomarkers/targets of NAFLD/NASH-associated hepatocarcinogenesis.

Metabolomics and Lipidomics Screening Reveal Reprogrammed Signaling Pathways toward Cancer Development in Non-Alcoholic Steatohepatitis

With the rising incidence of hepatocellular carcinoma (HCC) from non-alcoholic steatohepatitis (NASH), identifying new metabolic readouts that function in metabolic pathway perpetuation is still a demand. The study aimed to compare the metabolic signature between NASH and NASH-HCC patients to explore novel reprogrammed metabolic pathways that might modulate cancer progression in NASH patients. NASH and NASH-HCC patients were recruited and screened for metabolomics, and isotope-labeled lipidomics were targeted and profiled using the EXION-LCTM system equipped with a Triple-TOFTM 5600+ system. Results demonstrated significantly (p ≤ 0.05) higher levels of triacylglycerol, AFP, AST, and cancer antigen 19-9 in NASH-HCC than in NASH patients, while prothrombin time, platelet count, and total leukocyte count were decreased significantly (p ≤ 0.05). Serum metabolic profiling showed a panel of twenty metabolites with 10% FDR and p ≤ 0.05 in both targeted and non-targeted analysis that could segregate NASH-HCC from NASH patients. Pathway analysis revealed that the metabolites are implicated in the down-regulation of necroptosis, amino acid metabolism, and regulation of lipid metabolism by PPAR-α, biogenic amine synthesis, fatty acid metabolism, and the mTOR signaling pathway. Cholesterol metabolism, DNA repair, methylation pathway, bile acid, and salts metabolism were significantly upregulated in NASH-HCC compared to the NASH group. Metabolite-protein interactions network analysis clarified a set of well-known protein encoding genes that play crucial roles in cancer, including PEMT, IL4I1, BAAT, TAT, CDKAL1, NNMT, PNP, NOS1, and AHCYL. Taken together, reliable metabolite fingerprints are presented and illustrated in a detailed map for the most predominant reprogrammed metabolic pathways that target HCC development from NASH.

Electrospun Microfibers Modulate Intracellular Amino Acids in Liver Cells via Integrin β1

Although numerous recent studies have shown the importance of polymeric microfibrous extracellular matrices (ECMs) in maintaining cell behaviors and functions, the mechanistic nexus between ECMs and intracellular activities is largely unknown. Nevertheless, this knowledge will be critical in understanding and treating diseases with ECM remodeling. Therefore, we present our findings that ECM microstructures could regulate intracellular amino acid levels in liver cells mechanistically through integrin β1. Amino acids were studied because they are the fundamental blocks for protein synthesis and metabolism, two vital functions of liver cells. Two ECM conditions, flat and microfibrous, were prepared and studied. In addition to characterizing cell growth, albumin production, urea synthesis, and cytochrome p450 activity, we found that the microfibrous ECM generally upregulated the intracellular amino acid levels. Further explorations showed that cells on the flat substrate expressed more integrin β1 than cells on the microfibers. Moreover, after partially blocking integrin β1 in cells on the flat substrate, the intracellular amino acid levels were restored, strongly supporting integrin β1 as the linking mechanism. This is the first study to report that a non-biological polymer matrix could regulate intracellular amino acid patterns through integrin. The results will help with future therapy development for liver diseases with ECM changes (e.g., fibrosis).

Diet and liver cancer risk: a narrative review of epidemiological evidence

Primary liver cancer is the third leading cause of cancer-related death worldwide. Most patients are diagnosed at late stages with poor prognosis; thus, identification of modifiable risk factors for primary prevention of liver cancer is urgently needed. The well-established risk factors of liver cancer include chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), heavy alcohol consumption, metabolic diseases such as obesity and diabetes, and aflatoxin exposure. However, a large proportion of cancer cases worldwide cannot be explained by current known risk factors. Dietary factors have been suspected as important, but dietary aetiology of liver cancer remains poorly understood. In this review, we summarised and evaluated the observational studies of diet including single nutrients, food and food groups, as well as dietary patterns with the risk of developing liver cancer. Although there are large knowledge gaps between diet and liver cancer risk, current epidemiological evidence supports an important role of diet in liver cancer development. For example, exposure to aflatoxin, heavy alcohol drinking and possibly dairy product (not including yogurt) intake increase, while intake of coffee, fish and tea, light-to-moderate alcohol drinking and several healthy dietary patterns (e.g. Alternative Healthy Eating Index) may decrease liver cancer risk. Future studies with large sample size and accurate diet measurement are warranted and need to consider issues such as the possible aetiological heterogeneity between liver cancer subtypes, the influence of chronic HBV or HCV infection, the high-risk populations (e.g. cirrhosis) and a potential interplay with host gut microbiota or genetic variations.

Therapeutic Effects of Amino Acids in Liver Diseases: Current Studies and Future Perspectives

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver and the third most common cause of cancer-related death worldwide. HCC is caused by infection of hepatitis B/C virus and liver dysfunctions, such as alcoholic liver disease, nonalcoholic fatty liver disease, and cirrhosis. Amino acids are organic substances containing amine and carboxylic acid functional groups. There are over 700 kinds of amino acids in nature, but only about 20 of them are used to synthesize proteins in cells. Liver is an important organ for protein synthesis, degradation and detoxification as well as amino acid metabolism. In the liver, there are abundant non-essential amino acids, such as alanine, aspartate, glutamate, glycine, and serine and essential amino acids, such as histidine and threonine. These amino acids are involved in various cellular metabolisms, the synthesis of lipids and nucleotides as well as detoxification reactions. Understanding the role of amino acids in the pathogenesis of liver and the effects of amino acid intake on liver disease can be a promising strategy for the prevention and treatment of liver disease. In this review, we describe the biochemical properties and functions of amino acids and to review how they have been applied to treatment of liver diseases.

Associations of branched-chain amino acids with parameters of energy balance and survival in colorectal cancer patients: Results from the ColoCare Study

BACKGROUND

Branched-chain amino acids (BCAA) have been previously linked to survival in colorectal cancer (CRC) patients. It is unclear whether BCAAs are prognostic biomarkers or surrogate markers for energy balance.

OBJECTIVES

We aimed to determine correlations of BCAAs with markers of energy balance over time and to investigate prognostic significance of BCAAs in CRC.

METHODS

We used urinary samples from newly diagnosed CRC patients [n=163; (stage I - IV)] from the ColoCare study in Heidelberg, Germany, collected at surgery (n=163), 6 (n=83) and 12 months follow-up (n=54). Isoleucine, leucine, valine, (2Z)-3-methylglutaconic acid (3HM), 2-ethylhydracrylic acid (2EA), 2-methyl-3-hydroxybutyrate (2M3H) were detected using gas-chromatography mass-spectrometry and proton-nuclear-magnetic-resonance spectroscopy. Partial correlation coefficients between BCAAs with body mass index (BMI), physical activity (metabolic equivalent [MET]) and muscle area were computed and adjusted for sex and age at diagnosis. We used Cox proportional hazard models to investigate overall survival (OS) after 24 months of follow-up.

RESULTS

We did not observe significant correlations between BCAAs and parameters of energy balance at all time points (correlation ranges: BMI: r= -0.13 to -0.01; METs: r=-0.14 to 0.02; dorsal muscle: r=-0.03 to 0.10). BCAAs were not associated with risk of death in stage I-III (e.g., valine: HR_log2=1.62, p=0.25) or in stage IV tumors. Elevated concentrations of 2EA and 2M3H were significantly associated with OS, independent of stage (2EA: stage I-III: HR_log2=0.42, p=0.04; stage IV: HR_log2=0.51, p=0.01).

CONCLUSION

Our study suggests that BCAAs in colorectal cancer patients do not reflect parameters of energy balance and may be independently associated with overall survival.

Plasma-free amino acid profiles are predictors of cancer and diabetes development

Type 2 diabetes (T2D) and cancers are two major causes of morbidity and mortality worldwide. Nowadays, there is convincing evidence of positive associations between T2D and the incidence or prognosis of a wide spectrum of cancers, for example, breast, colon, liver and pancreas. Many observational studies suggest that certain medications used to treat hyperglycemia (or T2D) may affect cancer cells directly or indirectly. The potential mechanisms of the direct T2D cancer links have been hypothesized to be hyperinsulinemia, hyperglycemia and chronic inflammation; however, the metabolic pathways that lead to T2D and cancers still remain elusive. Plasma-free amino acid (PFAA) profiles have been highlighted in their associations with the risks of developing T2D and cancers in individuals with different ethnic groups and degree of obesity. The alterations of PFAAs might be predominately caused by the metabolic shift resulted from insulin resistance. The underlying mechanisms have not been fully elucidated, in particular whether the amino acids are contributing to these diseases development in a causal manner. This review addresses the molecular and clinical associations between PFAA alterations and both T2D and cancers, and interprets possible mechanisms involved. Revealing these interactions and mechanisms may improve our understanding of the complex pathogenesis of diabetes and cancers and improve their treatment strategies.

Combination of aspartic acid and glutamic acid inhibits tumor cell proliferation

Placental extract contains several biologically active compounds, and pharmacological induction of placental extract has therapeutic effects, such as improving liver function in patients with hepatitis or cirrhosis. Here, we searched for novel molecules with an anti-tumor activity in placental extracts. Active molecules were separated by chromatographic analysis, and their antiproliferative activities were determined by a colorimetric assay. We identified aspartic acid and glutamic acid to possess the antiproliferative activity against human hepatoma cells. Furthermore, we showed that the combination of aspartic acid and glutamic acid exhibited enhanced antiproliferative activity, and inhibited Akt phosphorylation. We also examined in vivo tumor inhibition activity using the rabbit VX2 liver tumor model. The treatment mixture (emulsion of the amino acids with Lipiodol) administered by hepatic artery injection inhibited tumor cell growth of the rabbit VX2 liver. These results suggest that the combination of aspartic acid and glutamic acid may be useful for induction of tumor cell death, and has the potential for clinical use as a cancer therapeutic agent.

Metabolic and Physiological Roles of Branched-Chain Amino Acids

Branch chain amino acids (BCAAs) have unique properties with diverse physiological and metabolic roles. They have functions other than simple nutrition. Different diseases including metabolic disease lead to protein loss, especially muscle protein. Supplementation of BCAAs promotes protein synthesis and reduces break down, as well as improving disease conditions. They are important regulators of mTOR signaling pathway and regulate protein synthesis as well as protein turnover. BCAAs facilitate glucose uptake by liver and SK muscle and also enhance glycogen synthesis. Oxidation of BCAAs seems to be beneficial for metabolic health as their catabolism increases fatty acid oxidation and reduces risk of obesity. BCAAs are also important in immunity, brain function, and other physiological aspects of well-being. All three BCAAs are absolutely required for lymphocyte growth and proliferation. They are also important for proper immune cell function. BCAAs may influence brain protein synthesis, and production of energy and may influence synthesis of different neurotransmitters. BCAAs can be used therapeutically and future studies may be directed to investigating the diverse effects of BCAAs in different tissues and their signaling pathways.

Oral supplementation with branched-chain amino acid granules prevents hepatocarcinogenesis in patients with hepatitis C-related cirrhosis: A propensity score analysis

AIM

It has been reported that branched-chain amino acids (BCAA) supplementation can improve nutritional status and reduce liver-related complications in patients with decompensated cirrhosis. BCAA supplementation reportedly reduces the incidence of hepatocellular carcinoma (HCC) in obese cirrhotic patients infected with hepatitis C virus (HCV). We investigated the effects of oral supplementation with BCAA granules on hepatocarcinogenesis in patients with HCV-related cirrhosis using propensity score matching.

METHODS

A total of 60 patients with HCV-related cirrhosis and without history of HCC who were selected by one-to-one matching of propensity scores: 30 patients receiving 12 g/day of BCAA granules for 3 months or more (BCAA group) and 30 being observed without BCAA supplementation (control group). The impact of BCAA supplementation was analyzed on the incidence of HCC.

RESULTS

The 3- and 5-year rates of HCC development were 13.7% and 13.7% in the BCAA group and 35.1% and 44.5% in the control group, respectively. The BCAA group had a significantly lower rate of HCC than the control group (P = 0.032). Multivariate analysis for factors that were associated with hepatocarcinogenesis indicated that BCAA supplementation was independently associated with a reduced incidence of HCC (hazard ratio 0.131; 95% confidence interval, 0.032-0.530; P = 0.004) along with sex and serum α-fetoprotein. Obesity (body mass index, ≥25 kg/m(2) ) was not significantly associated with an increased incidence of HCC.

CONCLUSION

Oral supplementation with BCAA granules is associated with a reduced incidence of HCC in patients with HCV-related cirrhosis regardless of the presence of obesity based on the propensity score analysis.

Branched-chain amino acids in liver diseases

Branched chain amino acids (BCAAs) have been shown to affect gene expression, protein metabolism, apoptosis and regeneration of hepatocytes, and insulin resistance. They have also been shown to inhibit the proliferation of liver cancer cells in vitro, and are essential for lymphocyte proliferation and dendritic cell maturation. In patients with advanced chronic liver disease, BCAA concentrations are low, whereas the concentrations of aromatic amino acids such as phenylalanine and tyrosine are high, conditions that may be closely associated with hepatic encephalopathy and the prognosis of these patients. Based on these basic observations, patients with advanced chronic liver disease have been treated clinically with BCAA-rich medicines, with positive effects.

Effects of oral branched-chain amino acids on hepatic encephalopathy and outcome in patients with liver cirrhosis

Branched-chain amino acids (BCAAs) constituting of valine, leucine, and isoleucine act as both substrates of proteins and as key regulators for various nutrient metabolisms. Patients with liver cirrhosis frequently lack sufficient BCAAs and therefore suffer from various metabolic disorders. Hepatic encephalopathy (HE) is a severe metabolic disorder with neurologic manifestations such as flapping tremors and coma in patients with liver cirrhosis. In addition, a mild form of HE known as minimal HE (MHE) is an important social issue because it occurs in up to 80% of patients with chronic liver disease and affects prognosis and activities of daily living, possibly resulting in falls and motor vehicle accidents. Although HE/MHE can be caused by various pathological conditions, including in an accumulation of mercaptans, short-chain fatty acids, and alterations in the gut flora, hyperammonemia has also been implicated in an important pathogenesis of HE/MHE. Besides urea cycle of liver, ammonia can be detoxified in the skeletal muscles by the amidation process for glutamine synthesis using BCAAs. Thus, BCAA supplementation may enhance detoxification of ammonia in skeletal muscle and may be a possible therapeutic strategy for HE/MHE. In this review, we summarize the clinical impacts of BCAA supplementation on HE/MHE and discuss possible mechanisms for a BCAA-induced improvement of HE/MHE. Furthermore, we present some modifications of oral BCAA therapy for improvement of efficacy in HE treatment. We also briefly describe pleiotropic benefits of BCAAs on life-threatening events and overall prognosis in patients with liver cirrhosis.

The effect of long-term supplementation with branched-chain amino acid granules in patients with hepatitis C virus-related hepatocellular carcinoma after radiofrequency thermal ablation

GOALS

To elucidate whether long-term supplementation with branched-chain amino acid (BCAA) granules improves overall survival (OS) and recurrence-free survival (RFS) after radiofrequency thermal ablation (RFA) in patients with hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC)≤3 cm in diameter with up to 3 nodules and a serum albumin level before RFA of ≤3.5 g/dL.

BACKGROUND

Whether BCAA treatment after curative RFA for patients with HCV-related HCC improves OS and RFS remains unclear.

STUDY

We compared the OS rate and the RFS rate between the BCAA group (n=115) and the control group (n=141). We also examined factors contributing to OS and RFS.

RESULTS

The 1 and 3 years OS rates after RFA were 94.0% and 70.0%, respectively, in the BCAA group, and 94.0% and 49.8%, respectively, in the control group (P=0.001). The corresponding RFS rates 1 and 3 years after RFA were 61.8% and 28.0%, respectively, in the BCAA group, and 52.0% and 12.0%, respectively, in the control group (P=0.013). In the multivariate analysis, in terms of OS, BCAA treatment, and serum albumin level of ≥3.4 g/dL, and in terms of RFS, age 70 years or older, BCAA treatment, and a serum albumin level of ≥3.4 g/dL were significant independent factors, respectively.

CONCLUSIONS

BCAA treatment may improve OS and RFS after RFA in patients with HCV-related HCC≤3 cm in diameter with up to 3 nodules and a serum albumin level before RFA of 3.5 g/dL.

Hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma and future treatments for the poor responders

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. The most common problem associated with HCC is a high risk of intrahepatic recurrence despite radical treatment, and in many patients, this recurrence has fatal consequences. For patients with advanced-stage HCC according to the Barcelona Clinic Liver Cancer staging system, the multikinase inhibitor sorafenib is the current standard of care. In contrast, hepatic arterial infusion chemotherapy (HAIC) is the recommended treatment in Japan for patients with intermediate-stage or advanced-stage HCC. In this review, we describe the use of HAIC for advanced HCC. Furthermore, we demonstrate an alternative therapy for HCC, the iron chelator deferoxamine, and discuss future therapeutic possibilities.

Does a late evening meal reduce the risk of hepatocellular carcinoma among patients with chronic hepatitis C?

AIM

Some studies have suggested that nutritional support might protect against the recurrence of hepatocellular carcinoma (HCC) among postoperative HCC patients. However, no epidemiological studies have evaluated the effect of nutritional support on HCC incidence. This study aimed to investigate the association between a late evening meal and HCC.

METHODS

We conducted a hospital-based, case-control study comparing 73 cases with HCC to 253 matched controls among patients with chronic hepatitis C. A questionnaire elicited information on the consumption of a late evening meal, which was defined as a snack or meal within 2 h before bedtime. The odds ratios (OR) and 95% confidence intervals (CI) were calculated by the conditional logistic regression model.

RESULTS

After adjustment for potential confounders, patients who consumed a late evening meal had a lower OR as compared to those who did not consume one (OR, 0.08; 95% CI, 0.01-0.48). In terms of frequency of intake, a clear inverse exposure-response relationship was observed (trend P = 0.009). In addition, a negative association between a late evening meal and HCC was more pronounced among patients with an alpha-fetoprotein level of less than 20 ng/mL and those with a body mass index of less than 25 kg/m(2).

CONCLUSION

A late evening meal might protect against HCC, particularly among patients with a normal alpha-fetoprotein level and who are not obese, although these relations might be accounted for other factors, including total energy intake. Further studies with larger study sizes are needed to corroborate these findings.

Long-term oral branched chain amino acids in patients undergoing chemoembolization for hepatocellular carcinoma: a randomized trial

BACKGROUND

Patients undergoing transarterial chemoembolization for hepatocellular carcinoma have advanced tumour or severe cirrhosis and frequently have associated protein-calorie malnutrition. The role of nutritional supplements for such patients is unclear.

AIM

To investigate, in a randomized controlled trial, any benefit of the long-term administration of branched chain amino acids in patients undergoing chemoembolization for hepatocellular carcinoma.

METHODS

Forty-one patients received oral branched chain amino acids for up to four courses of chemoembolization and 43 patients did not receive any nutritional supplement. Morbidity, liver function, nutritional status, quality of life and long-term survival were compared between the two groups.

RESULTS

The administration of branched chain amino acids resulted in a lower morbidity rate compared with the control group (17.1% vs. 37.2%, P = 0.039). In particular, the group given branched chain amino acids showed a significantly lower rate of ascites (7.3% vs. 23.2%, P = 0.043) and peripheral oedema (9.8% vs. 27.9%, P = 0.034). Significantly higher serum albumin, lower bilirubin and a better quality of life were observed after chemoembolization in the group given branched chain amino acids. However, there was no significant difference in survival between the two groups.

CONCLUSIONS

Nutritional supplementation with oral branched chain amino acids is beneficial in increasing the serum albumin level, reducing the morbidity and improving the quality of life in patients undergoing chemoembolization for inoperable hepatocellular carcinoma.

Effect of the molar ratio of branched-chain to aromatic amino acids on growth and albumin mRNA expression of human liver cancer cell lines in a serum-free medium

Supplementation of branched-chain amino acids (BCAAs) is often used for the treatment of hepatic encephalopathy and low albuminemia in Japan. In this scenario, although many cases are complicated with hepatocellular carcinoma in chronic viral infection, the effect of BCAA levels on hepatocellular carcinoma cells remains unclear. We investigated the effect of the molar ratios of BCAAs to aromatic amino acids (AAAs) on the growth and albumin mRNA expression of cultured human liver cancer cell lines, HCC-M, HCC-T, PLC/PRF/5, and Hep G2. To exclude the effect of fetal serum in culture media on modification of the growth and albumin transcription of cell lines, we used a synthetic serum-free medium. We found that an increase in the molar ratio of BCAAs to AAAs reduced the growth of Hep G2 cells, and it increased albumin mRNA expression in this cell line at a molar ratio of 0.1-10. These results suggest that the molar ratio of BCAAs to AAAs affect the growth and mRNA expression of some liver cancer cells, and supplementation of BCAAs may at least be beneficial to patients with cirrhosis, even complicated with liver cancer.