Elsevier

Gene

Volume 486, Issues 1–2, 15 October 2011, Pages 104-109
Gene

Letter
No association of pre-microRNA-146a rs2910164 polymorphism and risk of hepatocellular carcinoma development in Turkish population: A case-control study

https://doi.org/10.1016/j.gene.2011.07.006Get rights and content

Abstract

Aim

MicroRNAs (miRNAs) are an abundant class of small non-protein coding RNAs with posttranscriptional regulatory functions as tumor suppressors and oncogenes. Aberrant expression and structural alteration of miRNAs are considered to participate in tumorigenesis and cancer development. It has been suggested that the presence of single nucleotide polymorphisms in precursor miRNAs (pre-miRNAs) can alter miRNA processing, expression, and/or binding to target mRNA and represent another type of genetic variability that can contribute to the susceptibility of human cancers. A G/C polymorphism (rs2910164), which is located in the sequence of miR-146a precursor, results in a change from G:U to C:U in its stem region.

Methods

To determine the association of the miR-146a rs2910164 polymorphism on the risk of hepatocellular carcinoma (HCC) development in Turkish population, a hospital-based case-control study was designed consisting of 222 subjects with HCC and 222 cancer-free control subjects matched on age, gender, smoking and alcohol status. The genotype frequency of miR-146a rs2910164 polymorphism was determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay.

Results

No statistically significant differences were found in the allele or genotype distributions of the miR-146a rs2910164 polymorphism among HCC and cancer-free control subjects (p > 0.05).

Conclusion

Our results demonstrate that the miR-146a rs2910164 polymorphism has nomajor role in genetic susceptibility to hepatocellular carcinogenesis, at least in the population studied here. Independent studies are needed to validate our findings in a larger series, as well as in patients of different ethnic origins.

Introduction

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third leading cause of cancer death. Because of its high fatality rates, the incidence and mortality rates are approximately equal (Parkin et al., 2005). Although chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections are the major cause of HCC, only a fraction of infected patients develop HCC during their lifetime, implying that genetic factors might contribute to the carcinogenic mechanism; therefore the identification of other risk characteristics (such as genetic polymorphisms) to stratify those individuals into high-risk populations is needed.

Recently, an increasing number of reports have described a new class of small regulatory RNA molecules termed MicroRNAs (miRNAs) that are implicated in HCC progression (Huang and He, 2011). miRNAs are evolutionarily conserved, endogenous, single-stranded, non-coding RNA molecules of ~ 20 nucleotides in length that function as negative regulators of gene expression (Bartel, 2004, Esquela-Kerscher and Slack, 2006). miRNAs are transcribed from endogenous DNA and processed from primary transcript (pri-microRNA) to hairpin precursor (pre-microRNA) comprising two strands: the leading strand used for production of mature miRNA and the passanger strand that is believed to be degraded. Mature miRNAs are involved in posttranscriptional gene expression by base pairing with target mRNAs of protein-coding genes, which has several possible consequences: it can result in the cleavage of mRNA or the repression of productive translation or even the destabilization and reduction in the mRNA concentration by accelerating poly (A) tail removal (Bartel, 2004, Bartel, 2005). Watson–Crick complementarity between the target and the seed region (2–8 nucleotides) of the mature miRNA is both necessary and sufficient for targeting and regulating of mRNAs by miRNAs. miRNAs have been implicated in a wide range of physiologic and pathologic processes, including development, cell differentiation, proliferation, apoptosis and carcinogenesis (Bartel, 2004). Although their biologic functions largely remain unclear, recent studies have demonstrated that miRNAs may function as tumor suppressors and/or oncogenes (Bartel, 2004, Esquela-Kerscher and Slack, 2006, Ryan et al., 2010).

A Homo sapiens miR-146 gene occurs in two distinct forms: miR-146a gene mapped to chromosome 5q33 and miR-146b encoded on chromosome 10q24. It has been reported that miR-146a and miR-146b, which display high similarity in their sequences, are overexpressed in HCC (Huang et al., 2008). Recently, single nucleotide polymorphism (SNP) has been identified in the miR-146a gene (guanine to cytosine (G/C)) (Hu et al., 2008). The reference number of this SNP in the database of the National Center for Biotechnology Information (NCBI) is rs2910164. G/C polymorphism is located in the stem region (at position + 60 relative to the first nucleotide of pre-miR-146a) opposite to the mature miR-146a sequence (placing it in the passenger strand) and results in a change from G:U pair to C:U mismatch in the stem structure of miR-146a precursor (Hu et al., 2008). The optimal free energy was decreased from − 42.40 kcal/mol for G to − 39.60 kcal/mol for C alleles, suggesting a less stable secondary structure for the C allele compared with the G allele (Hu et al., 2008). It has been observed that genetic variants in pre-microRNAs could change the conformation of the secondary structure and thereby alter the expression of mature miRNAs (Duan et al., 2007, Zeng and Cullen, 2003).

A few molecular epidemiological studies have investigated the association between the miR-146a rs2910164 polymorphism and the cancer risk including non-small cell lung cancer (Hu et al., 2008), breast cancer (Catucci et al., 2010, Hu et al., 2009, Pastrello et al., 2010, Shen et al., 2008), squamous cell carcinoma of head and neck (Liu et al., 2010) bladder cancer (Mittal et al., 2011), hepatocellular carcinoma (Xu et al., 2008), prostate cancer (Xu et al., 2010), esophageal cell carcinoma (Guo et al., 2010), gastric cancer (Okubo et al., 2010, Zeng et al., 2010), cervical squamous cell carcinoma (Zhou et al., 2011), familial ovarian cancer (Pastrello et al., 2010, Shen et al., 2008) and papillary thyroid carcinoma (Jazdzewski et al., 2008). However, the results of these studies have been remained controversial (Catucci et al., 2010, Guo et al., 2010, Hu et al., 2008, Hu et al., 2009, Jazdzewski et al., 2008, Liu et al., 2010, Mittal et al., 2011, Okubo et al., 2010, Pastrello et al., 2010, Shen et al., 2008, Xu et al., 2008, Xu et al., 2010, Zeng et al., 2010, Zhou et al., 2011).

Identification of SNPs that affect miRNA biogenesis pathway and contribute to disease predisposition has demonstrated recently, opening up a new avenue of investigation towards understanding the mechanisms for complex diseases such as cancer. In view of the role that miRNAs play in carcinogenesis and tumour formation, we hypothesized that functional rs2910164 polymorphism in miR-146a gene may act as a genetic modifier in individual susceptibility to HCC. According to our recent knowledge, no research has been conducted to evaluate miR-146a rs2910164 polymorphism and risk of HCC in Turkish population. To test the hypothesis that the polymorphism of miR-146a (rs2910164) is associated with risk of developing HCC, we performed genotyping analysis using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a hospital-based case-control study of 222 HCC patients and 222 age, gender, smoking and alcohol consumption matched cancer-free controls in Turkish population.

Section snippets

Study population

The study population and subject characteristics were previously described elsewhere (Akkız et al., 2010, Akkız et al., 2011). This is an ongoing molecular epidemiologic study of HCC conducted in Adana, Turkey and the subject recruitment was approved by the Committee for Ethics of Medical Experiment on Human Subjects, Faculty of Medicine, Çukurova University. Briefly, all subjects were genetically unrelated Turkish and were from Çukurova and the surrounding regions of southern Turkey.

General characteristic of the subjects

A total of 444 Turkish subjects were enrolled in our study. General characteristics of the subjects are summarized in Table 1. As expected, no significant difference was found between case patients and control subjects with regard to age and sex (p = 0.70 and p = 1.00, respectively) which implied that age and sex matched adequately. Similarly, there were no significant differences in smoking status and alcohol consumption between case and control group. In addition to these, Table 1 shows the

Discussion

As in many cancers, genetic polymorphisms of the genes involved in multistage of hepatocarcinogenesis may determine an individual's susceptibility to the development of HCC (Akkız et al., 2010, Akkız et al., 2011). The identification of SNPs that affect gene function or expression and contribute to HCC susceptibility is important as it may help to predict individual and population risk and clarify pathophysiologic mechanisms relevant to HCC. Moreover, identifying genetic biomarkers of HCC

Conflict of interest statement

All of the authors declare that there are no conflicts of interest.

Acknowledgements

The authors thank all the subjects who participated in this study. We also would like to thank Malik Atış for very helpful English corrections. This work was supported by Çukurova University Research FundTF2008BAP22.

References (38)

  • H. Guo

    A functional varient in microRNA-146a is associated with risk of esophageal squamous cell carcinoma in Chinese Han

    Fam. Cancer

    (2010)
  • Z. Hu

    Genetic variants of miRNA sequences and non small cell lung cancer survival

    J. Clin. Invest.

    (2008)
  • Z. Hu

    Common genetic variants in pre-microRNAs were associated with increased risk of breast cancer in Chinese women

    Hum. Mutat.

    (2009)
  • S. Huang et al.

    The role of microRNAs in liver cancer progression

    Br. J. Cancer

    (2011)
  • Y.S. Huang

    Microarray analysis of microRNA expression in hepatocellular carcinoma and non-tumorous tissues without viral hepatitis

    J. Gastroenterol. Hepatol.

    (2008)
  • D.R. Hurst et al.

    Breast cancer metastasis suppressor 1 up-regulates miR-146, which suppresses breast cancer metastasis

    Cancer Res.

    (2009)
  • International HapMap Project...
  • K. Jazdzewski et al.

    Common SNP in pre-miR-146a decreases mature miR expression and predisposes to papillary thyroid carcinoma

    Proc. Natl. Acad. Sci. U. S. A.

    (2008)
  • C. Labbaye

    A three-step pathway comprising PLZF/miR-146a/CXCR4 controls megakaryopoiesis

    Nat. Cell. Biol.

    (2008)
  • Cited by (80)

    • Study of the association between five polymorphisms and risk of hepatocellular carcinoma: A meta-analysis

      2017, Journal of the Chinese Medical Association
      Citation Excerpt :

      A total of 52 articles were retrieved after the first search in PubMed, ExcerptaMedica Database, Chinese Biomedical Literature Database, and Chinese National Knowledge Infrastructure. After our selection (Fig. 1), 21 case–control studies fulfilled the inclusion criteria, including those from China8–17,29–34 (16 studies), Korea18,19 (2 studies), and Turkey20–22 (3 studies). In total, those studies involved 10,145 HCC cases and 9907 healthy controls, evaluating the relationship between the polymorphisms in miRNA and HCC (Figs. 2 and 3).

    View all citing articles on Scopus
    1

    These two authors are contributed equally to this work.

    View full text