Liver, Pancreas and Biliary Tract
Association study of genetic variations in microRNAs with the risk of hepatitis B-related liver diseases

https://doi.org/10.1016/j.dld.2012.04.021Get rights and content

Abstract

Background and aims

MicroRNAs have been recently identified as important regulators that influence human carcinogenesis, cancer progression, and the interaction between the host and virus. This study investigates an association between microRNAs (miR-101-1, miR-101-2, and miR-338) and the risk of liver diseases through clearance of hepatitis B virus infection, development of liver cirrhosis, and hepatocellular carcinoma occurrence.

Methods

Genetic variations were genotyped using the TaqMan assay in 1439 Korean hepatitis B virus patients. To investigate the relationship between four polymorphisms in three microRNAs and the disease phenotypes, differences in frequency distribution of variations were analysed using logistic and multiple regression analyses after adjusting for age and gender as covariates.

Results

We find that the rs7536540 polymorphism in miR-101-1 is significantly associated with development of liver cirrhosis and hepatocellular carcinoma occurrence. In addition, rs12375841 and its unique haplotype (ht2) in miR-101-2 show significant association with clearance of hepatitis B virus infection.

Conclusions

To our knowledge, this is the first study to examine a relationship between the three microRNA genes and the risk of hepatitis B-related liver diseases. We expect that the findings in this study will be helpful to further genetic studies in the pathophysiology of hepatitis B virus-related liver diseases.

Introduction

Recently, microRNAs (miRNAs) have been identified as important regulators in cellular signalling [1]. MiRNAs constitute small, conserved RNA molecules with approximately 22 bases. They have emerged as important regulators in gene expression and cancer progression by functioning as post-transcriptional regulators or repressors [2]. To date, several reports have provided evidence that miRNAs serve as repressors for viral infection pathways. MiRNAs mediate RNA silencing in the innate antiviral pathways [3], [4]. In addition, viruses have miRNAs for regulating gene expression, which in turn contributes to the pathogenic aspect of the virus [5], [6]. Therefore, miRNAs are considered as key regulators in host–virus interactions and regulation of viral replication.

MiR-101-1 and miR-101-2 are known to be two predicted miR-101 precursor hairpin structures. MiR-101-1 is a short, non-coding RNA located on chromosome 1p31.3. It is involved in post-transcriptional regulation of target gene expression and is known as an important factor in host–virus interactions. Previous studies have revealed that miR-101-1 is related to Herpes simplex virus (HSV)-1 replication [4], [7]. Smits et al. found that miR-101-1 is downregulated in glioma in a grade-dependent manner [8], and Sachdeva et al. revealed that miR-101 can stimulate oestrogen-independent growth caused by upregulation of phosphorylated Akt [9]. The loss of miR-101-2, which is located in 9p24.1, has been found in prostate cancer and metastatic disease, suggesting a role as an important tumour suppressor [10], [11]. Recently, several findings to support the considerable role of miRNA-101 and miRNA-338 in the development of hepatocellular carcinoma (HCC) have been reported. Su et al. revealed that miR-101 was downregulated in both hepatoma cell lines and human HCC tissues, suggesting that it could inhibit tumour growth and stimulate hepatoma cell lines to apoptosis induced by chemotherapeutic drugs [12]. In addition, Budhu et al. have shown that reduced expression of miR-101 is related to a lower survival rate in HCC patients [13]. Li et al. found at least a twofold downregulation of miRNA-101 in 16 HCC samples when compared with matching non-tumour liver tissues, and revealed that high expression of miRNA-101 inhibited the invasion and migration of cultured HCC cells [14]. Taken together, these findings suggest a fundamental role of miR-101 in HCC development. In addition, the expression level of miR-338 has been found to be decreased in HCC tissues, and is significantly associated with HCC progression elements such as the tumour–node–metastasis stage, vascular invasion, intrahepatic metastasis, tumour size, and tumour grade [15].

However, although some reports indicate that miR-101 and miR-338 may be two causal genes of liver cancer and virus infection, the exact relationship of single nucleotide polymorphisms (SNPs) in miR-101 and miR-338 with clearance of the hepatitis B virus (HBV) and the risk of HCC occurrence remains uncertain.

In this study, we hypothesized that a genetic variation in miR-101 and miR-338 could connect the clearance of HBV and disease progression to incidence of liver cirrhosis and HCC in subjects with chronic HBV infection. To investigate the relationship between miR-101 and miR-338 and consequences of HBV infection, we genotyped polymorphisms in these two genes and carried out a case–control association analysis in a Korean population.

Section snippets

Subjects

To select the primary subjects for the case–control study, a total of 1439 individuals with either past or present evidence of HBV infection were recruited from patients enrolled in the outpatient clinic of the liver unit and the Center for Health Promotion at Seoul National University Hospital and Ajou University Medical Center. The diagnosis of chronic carrier was established based on seropositivity of the hepatitis B surface antigen (HBsAg; Enzygnost1 HBsAg 5.0; Dade Behring, Marburg,

Results

In this study, a total of 1439 subjects were recruited, including 404 spontaneously recovered (SR) controls and 1035 chronic carrier cases composed of 313 patients with chronic hepatitis, 305 patients with liver cirrhosis, and 417 HCC cases. The clinical profiles of the study subjects (Table 1) showed a higher prevalence of men than women among chronic carriers (77.1%) compared to SR subjects (67.3%). Clinical profiles of the study subjects are summarized in Table 1. All study subjects were of

Discussion

Chronic HBV infection causes diverse clinical courses that range from asymptomatic carrier to cirrhosis of the liver and HCC. Despite the many reports on the epidemiology and pathogenesis of HBV-derived liver diseases, the lengthy and heterogeneous HBV infection processes require better understanding of host genetic regulations and cellular responses of HBV [18]. Although it has been established that miRNAs are small, endogenous, non-coding RNAs (about 17–25 nucleotides in length) that play an

Source of funding

This work was supported by the Korea Science and Engineering Foundation (KOSEF) funded by the Korean government (MEST) (No. 2009-0080157), and by a National Research Foundation of Korea (NRF) grant, also funded by the Korean government (MEST) (No. 2011-0004227).

Conflict of interest

None declared.

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    These authors have equally contributed to this work.

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