Dataset Information

MicroRNA-21 is a potential link between non-alcoholic fatty liver disease and hepatocellular carcinoma via modulation of the HBP1-p53-Srebp1c pathway.

ABSTRACT:

Background

Non-alcoholic fatty liver disease (NAFLD) is a major risk factor for hepatocellular carcinoma (HCC). However, the mechanistic pathways that link both disorders are essentially unknown.

Objective

Our study was designed to investigate the role of microRNA-21 in the pathogenesis of NAFLD and its potential involvement in HCC.

Methods

Wildtype mice maintained on a high fat diet (HFD) received tail vein injections of microRNA-21-anti-sense oligonucleotide (ASO) or miR-21 mismatched ASO for 4 or 8 weeks. Livers were collected after that time period for lipid content and gene expression analysis. Human hepatoma HepG2 cells incubated with oleate were used to study the role of miR-21 in lipogenesis and analysed with Nile-Red staining. microRNA-21 function in carcinogenesis was determined by soft-agar colony formation, cell cycle analysis and xenograft tumour assay using HepG2 cells.

Results

The expression of microRNA-21 was increased in the livers of HFD-treated mice and human HepG2 cells incubated with fatty acid. MicroRNA-21 knockdown in those mice and HepG2 cells impaired lipid accumulation and growth of xenograft tumour. Further studies revealed that Hbp1 was a novel target of microRNA-21 and a transcriptional activator of p53. It is well established that p53 is a tumour suppressor and an inhibitor of lipogenesis by inhibiting Srebp1c. As expected, microRNA-21 knockdown led to increased HBP1 and p53 and subsequently reduced lipogenesis and delayed G1/S transition, and the additional treatment of HBP1-siRNA antagonised the effect of microRNA-21-ASO, suggesting that HBP1 mediated the inhibitory effects of microRNA-21-ASO on both hepatic lipid accumulation and hepatocarcinogenesis. Mechanistically, microRNA-21 knockdown induced p53 transcription, which subsequently reduced expression of genes controlling lipogenesis and cell cycle transition. In contrast, the opposite result was observed with overexpression of microRNA-21, which prevented p53 transcription.

Conclusions

Our findings reveal a novel mechanism by which microRNA-21, in part, promotes hepatic lipid accumulation and cancer progression by interacting with the Hbp1-p53-Srebp1c pathway and suggest the potential therapeutic value of microRNA-21-ASO for both disorders.

SUBMITTER: Wu H

PROVIDER: S-EPMC4882277 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Simple steatosis (SS) and non-alcoholic steatohepatitis (NASH) are subtypes of non-alcoholic fatty liver disease. The difference in pathogenesis between SS and NASH is still not clear. MicroRNAs (miRNAs) are endogenous, non-coding short RNAs that regulate gene expression. The aim of this study was to examine the relationship of miRNA expression profiles with SS and NASH in animal models and humans. Animal models DD Shionogi (DS), Fatty Liver Shionogi (FLS Wild; W), and FLS ob/ob mice were subjected as the normal control, SS model and NASH model, respectively. Male DS mice (Riken BRC No. 03706) were provided by Riken bio-resource center through the national bio-resource project of Japan. Male FLS W and male FLS-ob/ob mice were obtained from Shionogi research laboratories (Shiga, Japan). Animals were housed in a room maintained at a controlled temperature of 24 Â± 2 Ë?C under a 12-h light-dark cycle. Animals were provided ad libitum access to water and standard pellet feed. Five male mice of every strain (24 weeks old; mean body weight of DS, FLS W and FLS-ob/ob were 31.1 Â± 1.1g, 38.4 Â± 3.4g and 56.0 Â± 5.0g, respectively) were sacrificed under pentobarbital anesthesia by whole blood collection from the right ventricle. The livers were cut into about 200 mg pieces and fixed in 10% formalin for histological analysis or fresh-frozen in liquid nitrogen and stored at -80 Â°C in a freezer until use. miRNA expression analysis Total RNAs in mouse liver were isolated using TrizolReagent (Life Technologies, California, USA) as described the manufacturerâ??s protocol. The quality of total RNA samples was checked by applying the RNA Integrity Number (RIN) which is calculated by a proprietary algorithm of the Agilent 2100 Bioanalyzer expert software (Agilent technologies, CA, USA). Only high quality RNA, with RNA integrity number (RIN) greater than 8 and A260/280 and A260/230 greater than 1.8, will be considered for microarray analysis. TaqManÂ® Array Rodent MicroRNA A Card v2.0 (Thermo Fisher Scientific, MA, USA) was used to assess 375 miRNA expression profiles in mouse liver tissue.