ABSTRACT
INTRODUCTION AND OBJECTIVES: Autophagy has emerged as a critical regulatory pathway in non-alcoholic fatty liver disease (NAFLD). However, the variability of hepatic autophagy during NAFLD development remains controversial. This study aimed to elucidate the dynamics of hepatic autophagy and its underlying mechanism during NAFLD development both in vivo and in vitro. MATERIALS AND METHODS: Autophagy markers were evaluated in the livers of mice fed a high fat diet or a methionine-choline-deficient diet and in HepG2 cells treated with palmitic acid (PA) by western blotting. Intrahepatic and intracellular triacylglycerol levels were assessed using biochemical quantification and lipid staining. Autophagic flux was monitored using an LC3 turnover assay and tandem mRFP-GFP-LC3 fluorescence analysis. RESULTS: Hepatic autophagy was enhanced in early stages but blocked at later stages of NAFLD development both in vivo and in vitro. Analysis of autophagic flux revealed that both autophagic synthesis and degradation were initially activated and progressively inhibited afterwards. The activation of mammalian target of rapamycin complex 1 (mTORC1), a central regulator of autophagy, was found to be negatively correlated with autophagic synthesis; moreover, pharmacological inhibition of mTORC1 by rapamycin alleviated hepatic steatosis through recovery of autophagic flux in hepatocytes with prolonged PA treatment. CONCLUSIONS: Hepatic autophagy fluctuates during the development of NAFLD in which mTORC1 signalling plays a critical regulatory role, suggesting a therapeutic potential of autophagy modulation by targeting the mTORC1 signalling pathway in NAFLD.
Subject(s)
Autophagy , Hepatocytes/pathology , Liver/pathology , Non-alcoholic Fatty Liver Disease/pathology , Animals , Autophagy/drug effects , Autophagy-Related Proteins/genetics , Autophagy-Related Proteins/metabolism , Choline Deficiency/complications , Diet, High-Fat , Disease Models, Animal , Hep G2 Cells , Hepatocytes/drug effects , Hepatocytes/metabolism , Humans , Liver/drug effects , Liver/metabolism , Male , Mechanistic Target of Rapamycin Complex 1/antagonists & inhibitors , Mechanistic Target of Rapamycin Complex 1/metabolism , Methionine/deficiency , Mice , Non-alcoholic Fatty Liver Disease/drug therapy , Non-alcoholic Fatty Liver Disease/etiology , Non-alcoholic Fatty Liver Disease/metabolism , Palmitic Acid/pharmacology , Signal Transduction , Sirolimus/pharmacology , Time FactorsABSTRACT
BACKGROUND: Hepatocellular carcinoma (HCC) has a high morbidity and mortality. Single nucleotide polymorphisms (SNPs) of microRNA (miRNA) may be associated with the susceptibility to develop certain malignant tumors. AIM: To study the association between SNPs of miRNA and hepatocellular carcinoma in peripheral blood samples. MATERIAL AND METHODS: Three SNPs in miRNA were studied in peripheral blood samples of 498 patients with HCC and 520 controls. RESULTS: A significant association was observed between rs13299349 in miRNA3152 and HCC. AA genotype or A allele were significantly associated with increased risk of HCC. A allele was associated with the size and number of tumor foci. There was also a relationship between rs10061133 in miRNA449b and HCC. The G allele was significantly associated with increased risk of HCC compared with A allele. CONCLUSIONS: This study links rs13299349 in miRNA3152 and rs10061133 in miRNA449b with the risk of developing HCC.
Subject(s)
Carcinoma, Hepatocellular/genetics , Genetic Association Studies/methods , Liver Neoplasms/genetics , MicroRNAs/genetics , Polymorphism, Single Nucleotide , Adult , Aged , Analysis of Variance , Biomarkers, Tumor , Carcinoma, Hepatocellular/pathology , Case-Control Studies , Female , Gene Frequency , Genetic Predisposition to Disease , Genotyping Techniques , Humans , Liver Neoplasms/pathology , Male , Middle Aged , Reference Values , Risk Factors , Tumor BurdenABSTRACT
Background: Hepatocellular carcinoma (HCC) has a high morbidity and mortality. Single nucleotide polymorphisms (SNPs) of microRNA (miRNA) may be associated with the susceptibility to develop certain malignant tumors. Aim: To study the association between SNPs of miRNA and hepatocellular carcinoma in peripheral blood samples. Material and Methods: Three SNPs in miRNA were studied in peripheral blood samples of 498 patients with HCC and 520 controls. Results: A significant association was observed between rs13299349 in miRNA3152 and HCC. AA genotype or A allele were significantly associated with increased risk of HCC. A allele was associated with the size and number of tumor foci. There was also a relationship between rs10061133 in miRNA449b and HCC. The G allele was significantly associated with increased risk of HCC compared with A allele. Conclusions: This study links rs13299349 in miRNA3152 and rs10061133 in miRNA449b with the risk of developing HCC.
Antecedentes: El carcinoma hepatocelular (CHC) tiene una alta morbilidad y mortalidad. Polimorfismos de un nucleótido (SNP) presentes en el microRNA (miRNA) circulante pueden asociarse a ciertos tumores. Objetivo: Estudiar la asociación entre la presencia de SNPs en miRNA circulante y la presencia de carcinoma hepatocelular. Material y Métodos: Se determinó la presencia de tres SNP en microRNA de sangre periférica en 498 pacientes con CHC y 520 controles. Resultados: El SNP rs13299349 en el miRNA3152 se asoció con CHC. El genotipo AA o el alelo A se asociaron con un riesgo mayor de presentar un CHC. El alelo A se asoció además con el tamaño y número de focos del tumor. Se observó también una relación entre el SNP rs10061133 en el miRNA449b y HCC. En este caso, el alelo G se relacionó con un mayor riesgo de CHC. Conclusiones: Los SNP rs13299349 en el miRNA3152 y rs10061133 en el miRNA449b se asocian al riesgo de desarrollar CHC.