Three common functional polymorphisms in microRNA encoding genes in the susceptibility to hepatocellular carcinoma: a systematic review and meta-analysis

Autophagy-related genes polymorphism in hepatitis B virus-associated hepatocellular carcinoma: A systematic review

BACKGROUND

Chronic hepatitis B (CHB) virus is the most common risk factor for developing liver malignancy. Autophagy is an essential element in human cell maintenance. Several studies have demonstrated that autophagy plays a vital role in liver cancer at different stages. In this systematic review, we intend to investigate the role of polymorphism and mutations of autophagy-related genes (ATGs) in the pathogenesis and carcinogenesis of the hepatitis B virus (HBV).

MATERIALS AND METHODS

The search was conducted in online databases (Web of Science, PubMed, and Scopus) using Viruses, Infections, Polymorphism, Autophagy, and ATG. The study was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria.

RESULTS

The primary search results led to 422 studies. By screening and eligibility evaluation, only four studies were relevant. The most important polymorphisms in hepatocellular carcinoma were rs2241880 in ATG16L1, rs77859116, rs510432, and rs548234 in ATG5. Furthermore, some polymorphisms are associated with an increased risk of HBV infection including, rs2241880 in ATG16L1 and rs6568431 in ATG5.

CONCLUSION

The current study highlights the importance of rs2241880 in ATG16L1 and rs77859116, rs510432, and rs548234 in ATG5 for HBV-induced HCC. Additionally, some mutations in ATG16L1 and ATG5 were important in risk of HBV infection. The study highlights the gap of knowledge in the field of ATG polymorphisms in HBV infection and HBV-induced HCC.

SNPs in miRNAs and Target Sequences: Role in Cancer and Diabetes

miRNAs are fascinating molecular players for gene regulation as individual miRNA can control multiple targets and a single target can be regulated by multiple miRNAs. Loss of miRNA regulated gene expression is often reported to be implicated in various human diseases like diabetes and cancer. Recently, geneticists across the world started reporting single nucleotide polymorphism (SNPs) in seed sequences of miRNAs. Similarly, SNPs are also reported in various target sequences of these miRNAs. Both the scenarios lead to dysregulated gene expression which may result in the progression of diseases. In the present paper, we explore SNPs in various miRNAs and their target sequences reported in various human cancers as well as diabetes. Similarly, we also present evidence of these mutations in various other human diseases.

miRNA-148b and its role in various cancers

miRNA-148b belongs to the family miR-148/-152, with significant differences in nonseed sequences, which can target diverse mRNA molecules. Reportedly, it may undergo deregulation in lung and ovarian cancers and downregulation in gastric, pancreatic and colon cancers. However, there is a need for further studies to better characterize its mechanism of action and in different types of cancer. In this review, we focus on the aberrant expression of miR-148b in different cancer types and highlight its main target genes and signaling pathways, as well as its pathophysiologic role and relevance to tumorigenesis in several types of cancer.

Relationships between IL-1β, TNF-α genetic polymorphisms and HBV infection: A meta-analytical study

BACKGROUND

IL-1β and TNF-α have been demonstrated as pro-inflammatory cytokines to participate in the innate immune response and suppression of HBV infection. However, the exact relationship between IL-1β, TNF-α gene polymorphisms and HBV infection remains unknown. Our study aims to assess the associations between IL-1β, TNF-α gene polymorphisms and HBV infection.

METHODS

A systematic literature search of PubMed and Embase databases was conducted through February 2020, and studies that were included in the present meta-analysis should fulfil the following conditions: (1) case-control studies focusing on the associations between IL-1β, TNF-α polymorphisms and HBV infection; (2) patients in the case group should be tested positive for the HBsAg and/or HBV-DNA without liver cirrhosis or hepatocellular carcinoma; (3) the control group including healthy population or HBV spontaneous clearance population; (4) odds ratios (ORs) and their 95% confidence intervals (CIs) could be calculated based on the allele and genotype frequencies provided in articles. The quality of included studies was assessed according to the Newcastle-Ottawa scale (NOS) assessment system. Pooled ORs and 95% CIs were used to analyze the strength of associations. Subgroup analysis was performed according to ethnicity and control type.

RESULTS

In the present meta-analysis, 49 articles including 10,218 cases and 9,557 controls were enrolled and seven polymorphisms (IL-1β rs16944, rs1143634, TNF-α rs1799724, rs1799964, rs1800629, rs1800630, rs361525) were studied. In overall meta-analysis, significant associations were found in IL-1β rs1143634, TNF-α rs1799724 and TNF-α rs1799964. For subgroup analysis under ethnicity, TNF-α rs1799724 and rs1800630 were markedly related to HBV infection in both Asian and Caucasian populations. In terms of control type subgroup, TNF-α rs1799724, rs1799964, rs1800630 were significantly associated with HBV persistence in HBV spontaneous clearance group.

CONCLUSION

In the present study, we identified that three polymorphisms (IL-1β rs1143634, TNF-α rs1799724, rs1799964) might serve as potential genetic biomarkers in HBV infection.

In silico Analysis of Polymorphisms in microRNAs Deregulated in Alzheimer Disease

BACKGROUND

Alzheimer's disease (AD) is a degenerative condition characterized by progressive cognitive impairment and dementia. Findings have revolutionized current knowledge of miRNA in the neurological conditions. Two regulatory mechanisms determine the level of mature miRNA expression; one is miRNA precursor processing, and the other is gene expression regulation by transcription factors. This study is allocated to the in-silico investigation of miRNA's SNPs and their effect on other cell mechanisms.

METHODS

We used databases which annotate the functional effect of SNPs on mRNA-miRNA and miRNA-RBP interaction. Also, we investigated SNPs which are located on the promoter or UTR region.

RESULTS

miRNA SNP3.0 database indicated several SNPs in miR-339 and miR-34a in the upstream and downstream of pre-miRNA and mature miRNAs. While, for some miRNAs miR-124, and miR-125, no polymorphism was observed, and also miR-101 with ΔG -3.1 and mir-328 with ΔG 5.8 had the highest and lowest potencies to produce mature microRNA. SNP2TFBS web-server presented several SNPs which altered the Transcription Factor Binding Sites (TFBS) or generated novel TFBS in the promoter regions of related miRNA. At last, RBP-Var database provided a list of SNPs which alter miRNA-RBP interaction pattern and can also influence other miRNAs' expression.

DISCUSSION

The results indicated that SNPs microRNA affects both miRNA function and miRNA expression. Our study expands molecular insight into how SNPs in different parts of miRNA, including the regulatory (promoter), the precursor (pre-miRNA), functional regions (seed region of mature miRNA), and RBP-binding motifs, which theoretically may be correlated to the Alzheimer's disease.

Mechanisms by Which Probiotic Bacteria Attenuate the Risk of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the second leading cause of cancer-related deaths worldwide. Chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV), alcoholic liver disease (ALD), and non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) are the major extrinsic risk factors of HCC development. Genetic background is pivotal in HCC pathogenesis, and both germline mutations and single nucleotide polymorphism (SNP) are intrinsic risk factors of HCC. These HCC risk factors predispose to hepatic injury and subsequent activation of fibrogenesis that progresses into cirrhosis and HCC. Probiotic bacteria can mitigate HCC risk by modulating host gut microbiota (GM) to promote growth of beneficial microbes and inhibit HCC-associated dysbiosis, thus preventing pathogen-associated molecular patterns (PAMPs)-mediated hepatic inflammation. Probiotics have antiviral activities against HBV and HCV infections, ameliorate obesity and risk of NAFLD/NASH, and their antioxidant, anti-proliferative, anti-angiogenic, and anti-metastatic effects can prevent the HCC pathogenesis. Probiotics also upregulate the expression of tumor suppressor genes and downregulate oncogene expression. Moreover, metabolites generated by probiotics through degradation of dietary phytochemicals may mitigate the risk of HCC development. These multiple anticancer mechanisms illustrate the potential of probiotics as an adjuvant strategy for HCC risk management and treatment.

Investigation of the Association of miRNA-499, miRNA-146a, miRNA-196a2 Loci with Hepatocellular Carcinoma Risk: A Case-Control Study Involving 1507 Subjects

microRNAs' (miRNAs) loci may influence hepatocellular carcinoma (HCC) development. Many recent studies have assessed the relationship between miRNA-499, miRNA-146a, and miRNA-196a2 loci and HCC risk. However, the observed results are conflicting. A total of 584 HCC patients and 923 age- and sex-matched controls were recruited. The correlation of miRNA-499 rs3746444, miRNA-146a rs2910164, and miRNA-196a2 rs11614913 with HCC development was assessed. In the <53-year-old subgroup, a correlation of the rs2910164 locus with HCC risk was found (GG/CG vs. CC: adjusted p = 0.011, GG vs. CC: adjusted p = 0.021 and CG vs. CC: adjusted p = 0.027). The association between miRNA-146a rs2910164 and the risk of HCC was also found in the never smoking (GG/CG vs. CC: adjusted p = 0.011 and CG vs. CC: adjusted p = 0.018). Using false-positive report probability method and power value, we identified that miRNA-146a rs2910164 conferred a risk to HCC in the <53-year-old and never-smoking subgroups. In conclusion, this study indicates rs2910164 may be a risk factor for HCC, especially in the <53-year-old and never-smoking subgroups.

A comprehensive evaluation of single nucleotide polymorphisms associated with hepatocellular carcinoma risk in Asian populations: A systematic review and network meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) have been inconsistently associated with hepatocellular carcinoma (HCC) risk. This meta-analysis aimed to synthesize relevant data on SNPs associated with HCC in the Asian population.

METHODS

Databases were searched to identify association studies of SNPs and HCC in Asians published through January 2019. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated based on 41 studies (13,167 patients with HCC and 15,886 noncancer controls). Network meta-analysis and Thakkinstian's algorithm were used to select the most appropriate genetic model, along with false positive report probability (FPRP) for noteworthy associations.

RESULTS

Eleven SNPs meeting the inclusion criteria were tested for association with HCC, including CCND1 rs9344, PTGS2 rs689466, IL18 rs187238 and rs1946518, KIF1B rs17401966, MDM2 rs2279744, MIR146A rs2910164, MIR149 rs2292832, MIR196A2 rs11614913, MIR499A rs3746444, and TGFB1 rs1800469. A significant increase for HCC risk was observed for MDM2 rs2279744, and the dominant (pooled OR = 1.59, 95% CI: 1.26-2.00) and codominant (pooled OR = 1.37, 95% CI: 1.18-1.60) models were determined to be the most appropriate models. MIR499A rs3746444 also showed a significant association with HCC risk under the allele contrast model (pooled OR = 1.36, 95% CI: 1.05-1.77). Only the significance of MDM2 rs2279744 was noteworthy (FPRP < 0.2).

CONCLUSIONS

MDM2 rs2279744 is associated with HCC susceptibility in Asians, and the dominant and codominant models are likely the most appropriate models to estimate HCC risk.

Overview of biological mechanisms of human carcinogens

This review summarizes the carcinogenic mechanisms for 109 Group 1 human carcinogens identified as causes of human cancer through Volume 106 of the IARC Monographs. The International Agency for Research on Cancer (IARC) evaluates human, experimental and mechanistic evidence on agents suspected of inducing cancer in humans, using a well-established weight of evidence approach. The monographs provide detailed mechanistic information about all carcinogens. Carcinogens with closely similar mechanisms of action (e.g. agents emitting alpha particles) were combined into groups for the review. A narrative synopsis of the mechanistic profiles for the 86 carcinogens or carcinogen groups is presented, based primarily on information in the IARC monographs, supplemented with a non-systematic review. Most carcinogens included a genotoxic mechanism.

A genetic variant in miR-100 is a protective factor of childhood acute lymphoblastic leukemia

BACKGROUND

In the past decade, miR-100, miR-146a, and miR-210 were reported to be dysregulated in childhood acute lymphoblastic leukemia (ALL). However, effects of genetic variants in these three microRNAs have not been investigated in Chinese population.

METHODS

In this study, we conducted a case-control study to evaluate the relationship between genetic variants in miR-100, miR-146a, and miR-210 and the risk of childhood ALL in Chinese population. Subsequently, plasma expression level of miR-100 was also detected.

RESULT

We found that subjects carrying mutant homozygous TT genotype of miR-100 rs543412 had a statistically significantly decreased risk of childhood ALL (adjusted odds ratio [OR] = 0.73, 95% confidence interval [CI] = 0.55-0.97, P = 0.029). This protective effect was also observed among subjects whose parents were ever drinkers (adjusted OR = 0.53, 95% CI = 0.29-0.94), or whose living house were ever painted (adjusted OR = 0.57, 95% CI = 0.34-0.94). Besides, rs543412 variant homozygous TT had a significantly protective role in patients with childhood B-ALL. Finally, we found that expression level of miR-100 in plasma of childhood ALL cases was significantly higher than that of noncancer controls.

CONCLUSION

Our study suggested that there was significant association between the polymorphisms in miR-100 (rs543412) and decreased susceptibility to childhood ALL.

Comprehensive assessment for miRNA polymorphisms in hepatocellular cancer risk: a systematic review and meta-analysis

MiRNA polymorphisms had potential to be biomarkers for hepatocellular cancer (HCC) susceptibility. Recently, miRNA single nucleotide polymorphisms (SNPs) were reported to be associated with HCC risk, but the results were inconsistent. We performed a systematic review with a meta-analysis for the association of miRNA SNPs with HCC risk. Thirty-seven studies were included with a total of 11821 HCC patients and 15359 controls in this meta-analysis. We found hsa-mir-146a rs2910164 was associated with a decreased HCC risk in the recessive model (P=0.017, OR = 0.90, 95% confidence interval (CI) = 0.83–0.98). While hsa-mir-34b/c rs4938723 was related with an increased HCC risk in the co-dominant model (P=0.016, odds ratio (OR) = 1.19, 95%CI = 1.03–1.37). When analyzing the Hepatitis B virus (HBV)-related HCC risk, hsa-mir-196a-2 rs11614913 was associated with a decreased HBV-related HCC risk in the co-dominant and allelic models. And hsa-mir-149 rs2292832 was found to be associated with a decreased HBV-related HCC risk in the dominant and recessive models. In conclusion, hsa-mir-146a rs2910164 and hsa-mir-34b/c rs4938723 could be biomarkers for the HCC risk while hsa-mir-196a-2 rs11614913 and hsa-mir-149 rs2292832 had potential to be biomarkers for HBV-related HCC risk.

Potential biomarkers of HCC based on gene expression and DNA methylation profiles

The aim of the present study was to identify potential biomarkers of hepatocellular carcinoma (HCC). Three gene expression profiles of GSE95698, GSE49515 and GSE76427 and a DNA methylation profile of GSE73003 were downloaded from the Gene Expression Omnibus (GEO) database, each comprising data regarding HCC and control tissue samples. The differentially expressed genes (DEGs) between the HCC group and the control group were identified using the limma software package. The Database for Annotation, Visualization and Integrated Discovery (DAVID) was used to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the overlapping DEGs. The PPI network of the overlapping DEGs was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins. A total of 41 DEGs were identified in HCC the group compared with control group. The overlapping DEGs were enriched in 11 GO terms and 3 KEGG pathways. A total of 6,349 DMSs were identified, and 6 of the differentially expressed genes were also differentially methylated [Denticleless protein homolog (DTL), Dual specificity phosphatase 1 (DUSP1), Eomesodermin, Endothelial cell specific molecule 1, Nuclear factor κ-light-chain gene enhancer of activated B cells inhibitor, α (NFKBIA) and suppressor of cytokine signaling 2 (SOCS2)]. The present study suggested that DTL, DUSP1, NFKBIA and SOCS2 may be potential biomarkers of HCC, and the tumor protein 'p53 signaling', 'forkhead box O1' signaling and 'metabolic' pathways may serve roles in the pathogenesis of HCC.

MicroRNA-Related Polymorphisms in Infectious Diseases-Tiny Changes With a Huge Impact on Viral Infections and Potential Clinical Applications

MicroRNAs (miRNAs) are single-stranded sequences of non-coding RNA with approximately 22 nucleotides that act posttranscriptionally on gene expression. miRNAs are important gene regulators in physiological contexts, but they also impact the pathogenesis of various diseases. The role of miRNAs in viral infections has been explored by different authors in both population-based as well as in functional studies. However, the effect of miRNA polymorphisms on the susceptibility to viral infections and on the clinical course of these diseases is still an emerging topic. Thus, this review will compile and organize the findings described in studies that evaluated the effects of genetic variations on miRNA genes and on their binding sites, in the context of human viral diseases. In addition to discussing the basic aspects of miRNAs biology, we will cover the studies that investigated miRNA polymorphisms in infections caused by hepatitis B virus, hepatitis C virus, human immunodeficiency virus, Epstein–Barr virus, and human papillomavirus. Finally, emerging topics concerning the importance of miRNA genetic variants will be presented, focusing on the context of viral infectious diseases.

Association Between MICA Gene Variants and the Risk of Hepatitis C Virus-Induced Hepatocellular Cancer in a Sicilian Population Sample

There are currently no biomarkers that predict hepatocellular carcinoma (HCC) risk in patients with hepatitis C virus (HCV)-related cirrhosis. We investigated the relationships among major histocompatibility complex (MHC) class I chain-related gene A (MICA) polymorphisms, plasma levels of soluble MICA (sMICA), and HCC risk in patients with HCV-related HCC. One hundred fifty-four HCV-related HCC patients, 93 HCV-related liver cirrhosis (LC) cases, and 244 healthy controls, all sampled from the native Sicilian population, were genotyped using the KASP^™ single-nucleotide polymorphism genotyping method. The MICA rs2596542 polymorphism showed that the G/G genotype was significantly more frequent in HCC than control subjects and LC patients (p < 0.005). For MICA rs2596538 polymorphism, the C allele and C/C genotype were significantly more frequent in HCC than in controls and LC cases (p < 0.005), after controlling for potential confounders. These results demonstrate that MICA rs2596542G/G, and particularly the rs2596538C/C polymorphism, are associated with the risk of developing HCV-related HCC in a Sicilian population sample. Importantly, using a machine learning classifier, we found that "age" and either rs2596542 or rs2596538 were important discriminating factors for patients with LC and HCC. Finally, sMICA levels significantly increased during HCV-related liver disease progression, while a significant relationship between both rs2596542 and rs2596538 genotypes and sMICA plasma levels was identified in patients with LC and HCC. In summary, the MICA rs2596538 and rs2596542 variants warrant further research for their clinical validity and utility in relationship to the risk of developing HCV-related HCC in independent populations.

Prognostic role of MIR146A polymorphisms for cardiovascular events in atrial fibrillation

There are few biomarkers able to forecast new thrombotic events in patients with AF. In this framework, microRNAs have emerged as critical players in cardiovascular biology. In particular, miR-146a-5p is recognised as an important negative regulator of inflammation. This study aims to evaluate the prognostic role and biological effect of functional MIR146A polymorphisms, rs2431697 and rs2910164, in non-valvular atrial fibrillation (AF) patients under oral anticoagulation. We studied 901 patients with permanent/paroxysmal AF stabilized for at least six months. Patients were followed-up for two years and adverse cardiovascular events (ACE) were recorded. In vitro studies were performed in monocytes from healthy homozygous for the two genotypes of rs2431697. Rs2910164 had no association with ACE. However, multivariate analysis (adjusted by CHA2DS2–VASc score) revealed that rs2431697TT was associated with adverse cardiovascular events [HR: 1.64 (1.09–2.47); p=0.017]. The predictive value of usefulness of the CHA2DS2–VASc+IL6+rs2431697 for predicting ACE, was statistically better than that predicted by CHA2DS2–VASc+IL6. Functional studies showed that after 24 hours incubation, monocytes from CC individuals showed a 65 % increase in miR-146a-5p levels, while TT individuals only showed a 28 % increase. Indeed, after 24 hours of LPS activation, TT monocytes showed a higher increase in IL6 mRNA expression than CC (52 % vs 26 %). Our study established MIR146A rs2431697 as a prognostic biomarker for ACE in anticoagulated AF patients. These data suggest that TT individuals, when submitted to an inflammatory stress, may be prone to a highest pro-inflammatory state due, in part, to lower levels of miR-146a-5p.

ESTABLISHMENT AND EVALUATION OF ORTHOTOPIC HEPATOCELLULAR CARCINOMA AND DRUG-INDUCED HEPATOCELLULAR CARCINOMA IN MICE WITH SPLEEN-DEFICIENCY SYNDROME IN TRADITIONAL CHINESE MEDICINE

BACKGROUND

Spleen-deficiency syndrome (SDS) in Traditional Chinese Medicine (TCM) played pivotal roles on the development of hepatocellular carcinoma (HCC). This study was performed to establish and evaluate HCC model in mice with SDS in TCM.

MATERIAL AND METHODS

A total of 90 C57BL/6 mice were randomized in six groups (n=15 for each group): A, Control group; B, SDS group; C, orthotopic HCC (OHCC) group; D, OHCC based on SDS (SDS-OHCC) group; E, Drug-induced HCC (DHCC) group; F, DHCC based on SDS (SDS-DHCC) group. The SDS model were established by subcutaneous injection of reserpine, followed by the OHCC or DHCC model establishment. The SDS scores, tumor formation rate and survival time were recorded and calculated, as well as the histochemical stain was performed.

RESULTS

The SDS scores of mice in Group B, D, F were 17.57±4.86 (P<0.05 vs. Group A), 18.13±4.53 (P<0.05 vs. Group A and C) and 23.32±4.94 (P<0.05 vs. Group A and E) respectively. The tumor formation rate of mice in Group C, D, E and F were 73.33%, 100%, 60% and 80% respectively. The survival time of mice in Group C, D, E and F were 26.42±5.27, 17.33±4.76 (P<0.05 vs. Group C), 35.77±6.12 and 22.61±5.05 (P<0.05 vs. Group E) respectively.

CONCLUSION

The SDS-oriented HCC mice models were simple and easily-operated models for further studies on SDS oriented tumor. Meanwhile, SDS was a pivotal factor for low outcome of hepatic tumor. Abbreviations: HCC, Hepatocellular carcinoma; OHCC, Orthotopic hepatocellular carcinoma; DHCC, Drug-induced hepatocellular carcinoma; SDS, Spleen-deficiency syndrome; TCM, Traditional Chinese Medicine; SPF, Specific pathogen-free; DEN, Diethylnitrosamine; CCl4, Carbon tetrachloride; HE, Hematoxylin-eosin; IACUC, Institutional Animal Care and Use Committee.

Hepatitis B virus X protein increases microRNA‑21 expression and accelerates the development of hepatoma via the phosphatase and tensin homolog/phosphoinositide 3‑kinase/protein kinase B signaling pathway

Hepatitis B virus (HBV) X protein (HBx) is a key regulatory protein that is involved in HBV infection, replication and carcinogenesis of hepatocellular carcinoma (HCC). The aim of the present study was to investigate the role of HBx in the progression and metastasis of liver cancer cells and to determine the underlying molecular mechanism of HBx in metastatic liver cancer cells. HBx protein expression was detected by western blot analysis, and microRNA (miR)‑21 levels were determined by reverse transcription‑quantitative polymerase chain reaction in the highly metastatic MHCC‑97H low metastatic MHCC‑97L and SMMC‑7721 liver cancer cell lines. The results demonstrated that the levels of HBx and miR‑21 were significantly increased in MHCC‑97H cells compared with MHCC‑97L and SMMC‑7721 cells. In addition, three pairs of small interfering (si)RNA specific to HBx were designed and synthesized to interfere with endogenous HBx in liver cancer cells, and the results demonstrated that knockdown HBx was associated with a corresponding decrease in miR‑21 expression. The MTT assay results demonstrated that cell viability significantly decreased in HBx‑siRNA cells compared with scramble siRNA‑transfected cells. In addition, transfection with an miR‑21 inhibitor inhibited MHCC‑97H cell proliferation. Furthermore, Transwell assay results revealed that downregulation of HBx and treatment with miR‑21 inhibitors contributed to the inhibition of MHCC‑97H cell invasion and metastasis. Western blot analysis demonstrated that miR‑21 inhibitors and HBx‑siRNA treatment led to the upregulation of phosphatase and tensin homolog (PTEN), and decreased levels of phosphoinositide 3‑kinase (PI3K), phosphorylated protein kinase B (Akt) and matrix metalloproteinase (MMP)‑2. The results of the present study indicated that HBx was positively associated with miR‑21 expression, and downregulation of miR‑21 and HBx suppressed MMP‑2 activity via the PTEN/PI3K/Akt signaling pathway. Therefore, HBx and miR‑21 may represent novel therapeutic targets for the treatment of HCC.

Allelic Interactions among Pto-MIR475b and Its Four Target Genes Potentially Affect Growth and Wood Properties in Populus

MicroRNAs (miRNAs) play crucial roles in plant growth and development, but few studies have illuminated the allelic interactions among miRNAs and their targets in perennial plants. Here, we combined analysis of expression patterns and single-nucleotide polymorphism (SNP)-based association studies to explore the interactions between Pto-MIR475b and its four target genes (Pto-PPR1, Pto-PPR2, Pto-PPR3, and Pto-PPR4) in 435 unrelated individuals of Populus tomentosa. Expression patterns showed a significant negative correlation (r = -0.447 to -0.411, P < 0.01) between Pto-MIR475b and its four targets in eight tissues of P. tomentosa, suggesting that Pto-miR475b may negatively regulate the four targets. Single SNP-based association studies identified 93 significant associations (P < 0.01, Q < 0.1) representing associations of 80 unique SNPs in Pto-MIR475b and its four targets with nine traits, revealing their potential roles in tree growth and wood formation. Moreover, one common SNP in the precursor region significantly altered the secondary structure of the pre-Pto-miR475b and changed the expression level of Pto-MIR475b. Analysis of epistatic interactions identified 115 significant SNP-SNP associations (P < 0.01) representing 45 unique SNPs from Pto-MIR475b and its four targets for 10 traits, revealing that genetic interactions between Pto-MIR475b and its targets influence quantitative traits of perennial plants. Our study provided a feasible strategy to study population genetics in forest trees and enhanced our understanding of miRNAs by dissecting the allelic interactions between this miRNA and its targets in P. tomentosa.

Impacts of CCL4 gene polymorphisms on hepatocellular carcinoma susceptibility and development

Hepatocellular carcinoma (HCC) is the sixth most common cancer globally and the third most common cause of cancer mortality. In Taiwan, HCC is the second leading cause of cancer death. CCL4 (C-C chemokine ligand 4), is a macrophage inflammatory protein with a chief effect in inflammation and immune-regulation, and was documented in cancer progression by promoting instability in the tumor environment. Polymorphisms in chemokine genes help to determine host-pathogen interactions that influence chemokine levels. We investigated the effects of CCL4 gene polymorphisms on the risk of hepatocellular carcinoma (HCC) disease progression in a cohort of Taiwanese patients. We recruited total of 1,546 participants in current study, including 1,200 healthy control and 346 patients with HCC. Three single-nucleotide polymorphisms (SNPs) of the CCL4 gene were examined by a real-time PCR. We found that the A/G homozygotes of CCL4 rs10491121 polymorphism reduced the risks for HCC. On the other hand, AG and GA haplotypes of 2 CCL4 SNPs (rs1049112 and rs171915) also reduced the risks for HCC by 0.025 and 0.515 fold, respectively. The present report is the first time to examine the risk factors associated with CCL4 SNPs in HCC progression in Taiwan.

The role of microRNA-196a in tumorigenesis, tumor progression, and prognosis

MicroRNAs are a large group of non-coding RNAs that have emerged as regulators of various biological processes, especially carcinogenesis and cancer progression. Recent evidence has shown that microRNA-196a (miR-196a) is upregulated in most types of tumors and involved in multiple biological processes via translational inhibition and mRNA cleavage, such as cell proliferation, migration, and invasion, mostly functioning as an oncogene. Dysregulation of miR-196a promotes oncogenesis and tumor progression. In this review, we summarize the upstream regulators, target genes, signaling pathways, and single nucleotide polymorphisms of miR-196a, which collectively affect cell proliferation, migration, and invasion. In addition, we review the clinical outcomes and significance of miR-196a. miR-196a may serve as a novel biomarker or target for diagnosis, prognosis, and therapy in several human cancers.

Association of the miR-196a2 C>T and miR-499 A>G polymorphisms with hepatitis B virus-related hepatocellular carcinoma risk: an updated meta-analysis

Background

This study meta-analyzed data on the possible association of the miR-196a2 C>T (rs11614913) and miR-499 A>G (rs3746444) polymorphisms with risk of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC).

Methods

Databases in PubMed, EMBASE, Web of Science, China BioMedicine, and Google Scholar were systematically searched to identify relevant studies. Meta-analyses were performed to examine the association of the miR-196a2 C>T and miR-499 A>G polymorphisms with HBV-related HCC risk. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

Results

A total of 13 studies involving 3,964 cases and 5,875 healthy controls were included. Random-effect meta-analysis showed that the T allele and TT genotype of miR-196a2 C>T were associated with significantly lower HBV-related HCC risk (allelic model, OR =0.84, 95% CI =0.71–0.99, P=0.04; homozygous model, OR =0.68, 95% CI =0.47–0.98, P=0.04). In contrast, miR-499 A>G showed no significant association with HBV-related HCC risk in either overall pooled analysis or ethnic subgroup analysis according to any of the four genetic models. Based on analysis of ethnic subgroups, neither miR-196a2 C>T nor miR-499 A>G was significantly associated with risk of HBV-related HCC in Chinese population.

Conclusion

The polymorphism miR-196a2 C>T, but not miR-499 A>G, may be associated with decreased HBV-related HCC risk. These conclusions should be verified in large, well-designed studies.

Association of the miRNA146a rs2910164 C>G Polymorphism with Head and Neck Cancer Risk: A Meta-analysis

OBJECTIVE

To investigate any association of the miRNA146a rs2910164 C>G polymorphism with head and neck cancer risk.

MATERIALS AND METHODS

The Medline, PubMed, PUBMED, EMBASE, Web of Science, WanFang and CNKI databases were searched and a meta-analysis was conducted using RevMan 5.2 software.

RESULTS

After searching and evaluating the literature, a total seven papers involving 2,766 patients with head and neck cancer and 6,603 healthy controls were included into this meta analysis. The results showed that there were no significant differences between patients and healthy controls overall for the miRNA rs2910164 C>G gene polymorphism (dominant model:OR=0.78, 95%CI:0.58-1.04, P=0.09; recessive model:OR=0.86, 95%CI:0.67-1.12, P=0.27;GG:CC:OR=0.75, 95%CI:0.52-1.08, P=0.12;GC:CC:OR=0.79, 95%CI:0.60-1.04, P=0.10). However, a significant association of miRNA rs2910164 C>G gene polymorphism with Chinese head and neck cancer risk was noted, limited to the dominant model (OR=0.68, 95%CI:0.50-0.95, P=0.02;GG:CC:OR=0.62, 95%CI:0.42-0.92, P=0.02;GC:CC:OR=0.72, 95%CI:0.520.99, P=0.04).

CONCLUSIONS

miRNA146a rs2910164 C>G polymorphism is not associated with head and neck cancer risk in general, but tehre may be link in Chinese.

Common functional polymorphism within miR-146a and miR-196a-2 as susceptibility loci for hepatocellular carcinoma: An updated meta-analysis

BACKGROUND

Mutations or single nucleotide polymorphisms (SNPs) within the gene region of microRNAs play an important role for the development of hepatocellular carcinoma (HCC). Extensive studies have tried to investigate the susceptibility role of miR-146a rs2819164 and miR-196a-2 rs11614913. However, these results are still inconsistent and inconclusive. We undertook a meta-analysis containing primarily Asian studies to assess the associations of the two SNPs with HCC risk.

METHODS

19 studies including miR-146a (7170 cases and 9443 controls) and 15 studies including miR-196a-2 (6417 cases and 7627 controls) were used for meta-analysis. Odds ratios and 95% CI were calculated to assess the association in five different genetic models.

RESULTS

For the rs2910164 polymorphism of miR-146a, significantly increased risks for HCC were observed when all studies were pooled under two models (CG vs CC: OR = 1.11, 95% CI = 1.02-1.21, P = 0.021; GG + CG vs CC: OR = 1.11, 95% CI = 1.01-1.22, P = 0.035). For the rs11614913 polymorphism of miR-196a-2, significant increased risks for HCC development were observed when all studies were pooled under four models (C vs T: OR = 1.14, 95% CI = 1.06-1.23, P = 0.001; CC vs TT: OR = 1.31, 95% CI = 1.12-1.53, P = 0.001; CC + TC vs TT: OR = 1.16, 95% CI = 1.03-1.31, P = 0.018; CC vs TC + TT: OR = 1.14, 95% CI = 1.00-1.30, P = 0.043).

CONCLUSION

Our results show that the two common SNPs within the miRNAs were associated with modest increased risk of HCC (OR < 1.6), especially in the Asian population. Larger population-based studies validating these results are needed.

Hepatitis B Virus Infection, MicroRNAs and Liver Disease

Hepatitis B virus (HBV) attacks the liver and can cause both acute as well as chronic liver diseases which might lead to liver cirrhosis and hepatocellular carcinoma. Regardless of the availability of a vaccine and numerous treatment options, HBV is a major cause of morbidity and mortality across the world. Recently, microRNAs (miRNAs) have emerged as important modulators of gene function. Studies on the role of miRNA in the regulation of hepatitis B virus gene expression have been the focus of modern antiviral research. miRNAs can regulate viral replication and pathogenesis in a number of different ways, which includefacilitation, direct or indirect inhibition, activation of immune response, epigenetic modulation, etc. Nevertheless, these mechanisms can appropriately be used with a diagnosticand/or therapeutic approach. The present review is an attempt to classify specific miRNAs that are reported to be associated with various aspects of hepatitis B biology, in order to precisely present the participation of individual miRNAs in multiple aspects relating to HBV.

MiR-17-92 cluster promotes hepatocarcinogenesis

MiR-17-92 cluster is an oncogenic miRNA cluster that is implicated in several cancers, although its role in hepatocarcinogenesis has not been clearly defined. In this study, we show that the miR-17-92 cluster is highly expressed in human hepatocellular carcinoma (HCC) tissues compared to the non-tumorous liver tissues by RT-PCR and in situ hybridization analyses. Increased miR-17-92 cluster expression in HCC tissues was further confirmed by analysis of the RNA-sequencing data of 319 patients available from the Cancer Genome Atlas (TCGA) Data Portal (https://tcga-data.nci.nih.gov/tcga/). To create an animal model that resembles enhanced miR-17-92 in the liver, we developed liver-specific miR-17-92 transgenic mice and the animals were treated with the hepatic carcinogen, diethylnitrosamine (DEN). We observed that the liver-specific miR-17-92 transgenic mice showed significantly increased hepatocellular cancer development compared to the matched wild-type control mice. Forced overexpression of the miR-17-92 cluster in cultured human hepatocellular cancer cells enhanced tumor cell proliferation, colony formation and invasiveness in vitro, whereas inhibition of the miR-17-92 cluster reduced tumor cell growth. By analyzing the miRNA and mRNA sequencing data from the 312 hepatocellular cancer patients available from the TCGA database, we observed that the expression levels of the miR-17-92 cluster members and host gene in the tumor tissues are negatively correlated with several target genes, including CREBL2, PRRG1, NTN4. Our findings demonstrate an important role of the miR-17-92 cluster in hepatocarcinogenesis and suggest the possibility of targeting this pivotal miRNA cluster for potential therapy.

Functional genetic variants in pre-miR-146a and 196a2 genes are associated with risk of lung cancer in North Indians

Objective: To find the association of two pre-miRNA polymorphisms with risk of lung cancer in North Indians. Materials & methods: Genotyping of 250 cases and 255 controls for miR-146a and miR-196a2 using PCR-RFLP. Results: Heterozygous subjects showed a risk toward lung cancer (LC), especially for adenocarcinoma (OR: 1.82; 95% CI: 1.04–3.20; p = 0.03) in miR-146a gene. TT genotype for miR-196a2 gene also showed 3.2-fold risk toward LC and the risk was fivefold higher for squamous cell carcinoma. Survival rate was significantly lower in subjects with TT genotype as compared with the CC genotype in miR-196a2. Conclusion: Both the single nucleotide polymorphism variants showed a positive association toward risk of lung cancer.

Biomarkers for hepatocellular carcinoma: diagnostic and therapeutic utility

Because of the high prevalence and associated-mortality of hepatocellular carcinoma (HCC), early diagnosis of the disease is vital for patient survival. In this regard, tumor size is one of the two main prognostic factors for surgical resection, which constitutes the only curative treatment for HCC along with liver transplantation. However, techniques for HCC surveillance and diagnosis that are currently used in clinical practice have certain limitations that may be inherent to the tumor development. Thus, it is important to continue efforts in the search for biomarkers that increase diagnostic accuracy for HCC. In this review, we focus on different biological sources of candidate biomarkers for HCC diagnosis. Although those biomarkers identified from biological samples obtained by noninvasive methods have greater diagnostic value, we have also considered those obtained from liver tissue because of their potential therapeutic value. To date, sorafenib is the only US Food and Drug Administration-approved antineoplastic for HCC. However, this therapeutic agent shows very low tumor response rates and frequently causes acquired resistance in HCC patients. We discuss the use of HCC biomarkers as therapeutic targets themselves, or as targets to increase sensitivity to sorafenib treatment.

Upregulation of microRNA-146a by hepatitis B virus X protein contributes to hepatitis development by downregulating complement factor H

Hepatic injuries in hepatitis B virus (HBV) patients are caused by immune responses of the host. In our previous study, microRNA-146a (miR-146a), an innate immunity-related miRNA, and complement factor H (CFH), an important negative regulator of the alternative pathway of complement activation, were differentially expressed in HBV-expressing and HBV-free hepatocytes. Here, the roles of these factors in HBV-related liver inflammation were analyzed in detail. The expression levels of miR-146a and CFH in HBV-expressing hepatocytes were assessed via analyses of hepatocyte cell lines, transgenic mice, adenovirus-infected mice, and HBV-positive human liver samples. The expression level of miR-146a was upregulated in HBV-expressing Huh-7 hepatocytes, HBV-expressing mice, and patients with HBV infection. Further results demonstrated that the HBV X protein (HBx) was responsible for its effects on miR-146a expression through NF-κB-mediated enhancement of miR-146a promoter activity. HBV/HBx also downregulated the expression of CFH mRNA in hepatocyte cell lines and the livers of humans and transgenic mice. Furthermore, overexpression and inhibition of miR-146a in Huh-7 cells downregulated and upregulated CFH mRNA levels, respectively. Luciferase reporter assays demonstrated that miR-146a downregulated CFH mRNA expression in hepatocytes via 3′-untranslated-region (UTR) pairing. The overall effect of this process in vivo is to promote liver inflammation. These results demonstrate that the HBx–miR-146a–CFH–complement activation regulation pathway might play an important role in the immunopathogenesis of chronic HBV infection. These findings have important implications for understanding the immunopathogenesis of chronic hepatitis B and developing effective therapeutic interventions.

Hepatitis B virus (HBV) remains an important pathogen and can cause severe liver diseases, including hepatitis, liver cirrhosis, and hepatocellular carcinoma. Although HBV was found in 1966, the molecular mechanisms of pathogenesis are still poorly understood. In the present study, we found that the HBV X protein (HBx) promoted the expression of miR-146a, an innate immunity-related miRNA, through the NF-κB signal pathway and that increasingly expressed miR-146a downregulated its target complement factor H (CFH), an important negative regulator of the complement alternative pathway, leading to the promotion of liver inflammation. We demonstrated that the HBx–miR-146a–CFH–complement activation regulation pathway is potentially an important mechanism of immunopathogenesis caused by chronic HBV infection. Our data provide a novel molecular mechanism of HBV pathogenesis and thus help to understand the correlations between the complement system, an important part of innate immunity, and HBV-associated disease. These findings will also be important to identify potential therapeutic targets for HBV infection.

Regulation of hypometabolism: insights into epigenetic controls

For many animals, survival of severe environmental stress (e.g. to extremes of heat or cold, drought, oxygen limitation, food deprivation) is aided by entry into a hypometabolic state. Strong depression of metabolic rate, often to only 1–20% of normal resting rate, is a core survival strategy of multiple forms of hypometabolism across the animal kingdom, including hibernation, anaerobiosis, aestivation and freeze tolerance. Global biochemical controls are needed to suppress and reprioritize energy use; one such well-studied control is reversible protein phosphorylation. Recently, we turned our attention to the idea that mechanisms previously associated mainly with epigenetic regulation can also contribute to reversible suppression of gene expression in hypometabolic states. Indeed, situations as diverse as mammalian hibernation and turtle anoxia tolerance show coordinated changes in histone post-translational modifications (acetylation, phosphorylation) and activities of histone deacetylases, consistent with their use as mechanisms for suppressing gene expression during hypometabolism. Other potential mechanisms of gene silencing in hypometabolic states include altered expression of miRNAs that can provide post-transcriptional suppression of mRNA translation and the formation of ribonuclear protein bodies in the nucleus and cytoplasm to allow storage of mRNA transcripts until animals rouse themselves again. Furthermore, mechanisms first identified in epigenetic regulation (e.g. protein acetylation) are now proving to apply to many central metabolic enzymes (e.g. lactate dehydrogenase), suggesting a new layer of regulatory control that can contribute to coordinating the depression of metabolic rate.

The association of common functional polymorphisms in mir-146a and mir-196a2 and hepatocellular carcinoma risk: evidence from a meta-analysis

MicroRNAs (miRNAs) are small non-coding RNA molecules that function as tumor suppressors or oncogenes. Single nucleotide polymorphisms (SNPs) located in the miRNAs influence the function of mature miRNAs and may contribute to cancer development. Studies investigating the association between miR-146a rs2910164 and miR-196a2 rs11614913 polymorphisms and hepatocellular carcinoma (HCC) risk reported inconsistent results. We performed a meta-analysis of all available studies to summarize this situation. Eligible studies were identified by search of electronic databases including PubMed, Embase, and Cochrane library for the period up to August 2014. The association of miR-146a rs2910164 and miR-196a2 rs11614913 polymorphisms and HCC risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). Finally, a total of 12 studies with 4171 cases and 4901 controls were included for miR-146a rs2910164 polymorphism and 10 studies with 4687 cases and 4990 controls were available for miR-196a2 rs11614913 polymorphism. With respect to miR-146a rs2910164 polymorphism, statistical significant increased HCC risk was found when all studies were pooled into the meta-analysis (GG+CG vs CC: OR = 1.097, 95% CI 1.005-1.197, P = 0.037). In subgroup analyses by ethnicity, source of control, and HWE in controls, significant increase of HCC risk was found in Asians, population-based studies, and studies consistent with HWE, but not in Caucasians, hospital-based studies, and studies inconsistent with HWE. With respect to miR-196a2 rs11614913 polymorphism, no significant association with HCC risk was found in the overall and subgroup analyses. The results suggest that the miR-146a rs2910164 polymorphism contributes to increased HCC susceptibility, especially in Asian populations. Further large and well-designed studies are required to validate this association.

A genetic variant in MiR-146a modifies digestive system cancer risk: a meta-analysis

MicroRNAs (miRNAs) negatively regulate gene expression and act as tumor suppressors or oncogenes in oncogenesis. The association between a single nucleotide polymorphism (SNP) in miR-146a rs2910164 and susceptibility to digestive system cancers was inconsistent in previous studies. In this study, we conducted a literature search of PubMed to identify all relevant studies published before August 31, 2013. A total of 21 independent case-control studies were included in this updated meta-analysis with 9,558 cases and 10,614 controls. We found that the miR-146a rs2910164 polymorphism was significantly associated with decreased risk of digestive system cancers in an allele model (OR=0.90, 95%CI 0.87-0.94), homozygote model (OR=0.84, 95%CI 0.77-0.91), dominant model (OR=0.90, 95%CI 0.84-0.96), and recessive model (OR=0.85, 95%CI 0.79-0.91), while in a heterozygous model (OR = 0.99, 95% CI 0.89-1.11) the association showed marginal significance. Subgroup analysis by cancer site revealed decreased risk in colorectal cancer above allele model (OR=0.90, 95%CI 0.83- 0.97) and homozygote model (OR=0.85, 95%CI 0.72-1.00). Similarly, decreased cancer risk was observed when compared with allele model (OR=0.87, 95%CI 0.81-0.93) and recessive model (OR=0.81, 95%CI 0.72-0.90) in gastric cancer. When stratified by ethnicity, genotyping methods and quality score, decreased cancer risks were also observed. This current meta-analysis indicated that miR-146a rs2910164 polymorphism may decrease the susceptibility to digestive system cancers, especially in Asian populations.

Associations of single nucleotide polymorphisms in miR-146a, miR-196a, miR-149 and miR-499 with colorectal cancer susceptibility

BACKGROUND

MicroRNAs (miRNAs) are an abundant class of endogenous small non-coding RNAs of 20-25 nucleotides in length that function as negative gene regulators. MiRNAs play roles in most biological processes, as well as diverse human diseases including cancer. Recently, many studies investigated the association between SNPs in miR-146a rs2910164, miR-196a2 rs11614913, miR-149 rs229283, miR-499 rs3746444 and colorectal cancer (CRC), which results have been inconclusive.

METHODOLOGY/PRINCIPAL FINDINGS

PubMed, EMBASE, CNKI databases were searched with the last search updated on November 5, 2013. For miR-196a2 rs11614913, a significantly decreased risk of CRC development was observed under three genetic models (dominant model: OR = 0.848, 95%CI: 0.735-0.979, P = 0.025; recessive model: OR = 0.838, 95%CI: 0.721-0.974, P = 0.021; homozygous model: OR = 0.754, 95%CI: 0.627-0.907, P = 0.003). In the subgroup analyses, miR-196a2*T variant was associated with a significantly decreased susceptibility of CRC (allele model: OR = 0.839, 95%CI: 0.749-0.940, P = 0.000; dominant model: OR = 0.770, 95%CI: 0.653-0.980, P = 0.002; recessive model: OR = 0.802, 95%CI: 0.685-0.939, P = 0.006; homozygous model: OR = 0.695, 95%CI: 0.570-0.847, P = 0.000). As for miR-149 rs2292832, the two genetic models (recessive model: OR = 1.199, 95% CI 1.028-1.398, P = 0.021; heterozygous model: OR = 1.226, 95% CI 1.039-1.447, P = 0.013) demonstrated increased susceptibility to CRC. On subgroup analysis, significantly increased susceptibility of CRC was found in the genetic models (recessive model: OR = 1.180, 95% CI 1.008-1.382, P = 0.040; heterozygous model: OR = 1.202, 95% CI 1.013-1.425, P = 0.013) in the Asian group.

CONCLUSIONS

These findings supported that the miR-196a2 rs11614913 and miR-149 rs2292832 polymorphisms may contribute to susceptibility to CRC.

MiR-146a rs2910164 G/C polymorphism and gastric cancer susceptibility: a meta-analysis

Background

Evidence has shown that single nucleotide polymorphism located in pre-miRNA or mature microRNA may modify various biological processes and affect the processing of carcinogenesis. Published results about the association between miR-146a rs2910164 G/C polymorphism and human gastric cancer susceptibility are inconclusive. The aim of this study was to acquire a more precise effect of the association between the miR-146a rs2910164 polymorphism and gastric risk by meta-analysis.

Methods

Eligible genetic association studies were searched from PubMed, Web of Knowledge and Chinese Biomedicine Database on human subject. Quantitative data synthesis was conducted for the associations of miR-146a rs2910164 G/C polymorphism with susceptibility to gastric cancer.

Results

Nine eligible studies that included a total of 3,885 gastric cancer patients and 5,396 controls were identified in the present meta-analysis. The overall OR indicated a potential association between rs2910164 polymorphism and GC but the effect was not statistically significant (GG vs. CG/CC: OR = 1.076, 95% CI 0.925-1.251, P = 0.342). When stratifying for population, the result showed that miR-146a rs2910164 GG genotype was associated with increased gastric cancer risk among Chinese in recessive model (GG vs. CG/CC: OR = 1.171, 95% CI 1.050-1.306, P = 0.005). Besides, no significant difference was found in gender, smoking, location, metastasis of lymph node and Laurèn’s classification.

Conclusions

The present meta-analysis suggests an increased risk between miR-146a rs2910164 GG genotype and gastric cancer susceptibility in Chinese based on published literatures.

Comprehensive assessment of the association between miRNA polymorphisms and gastric cancer risk

Single nucleotide polymorphisms (SNPs) in pri- or pre-microRNAs (miRNAs) were found to be associated with gastric cancer risk. The aim of this study was to systematically review with update meta-analysis for the association of miRNA SNPs with gastric cancer risk. We systematically reviewed a total of 31 SNPs in the precursor genes of 29 miRNAs associated with overall cancer risk. Meanwhile, 13 case-control studies with a total of 9044 gastric cancer cases and 11,762 controls were included in a meta-analysis of five highly studied pre-miRNA SNPs (miR-146a rs2910164, miR-196a2 rs11614913, miR-499 rs3746444, miR-149 rs2292832 and miR-27a rs895819). Our results show both the homozygous miR-27a rs895819 and the miR-149 rs2292832 heterozygote genotype were associated with a decreased risk of gastric cancer when compared with wild type. In the stratified analysis, in some subgroup, heterozygous miR-146a rs2910164 was associated with a decreased risk of gastric cancer; and the variant genotype of miR-196a-2 rs11614913 was associated with an increased risk. No association was found between miR-499 rs3746444 and gastric cancer risk. In summary, miR-27a rs895819 and miR-149 rs2292832 are of potential forewarning ability for gastric cancer risk.

High-resolution melting analysis reveals genetic polymorphisms in microRNAs confer hepatocellular carcinoma risk in Chinese patients

BACKGROUND

Although several single-nucleotide polymorphisms in microRNA (miRNA) genes have been associated with primary hepatocellular carcinoma, published findings regarding this relationship are inconsistent and inconclusive.

METHODS

The high-resolution melting (HRM) analysis was used to determine whether the occurrence of the SNPs of miR-146a C > G (rs2910164), miR-196a2 C > T (rs11614913), miR-301b A > G (rs384262), and miR-499 C > T (rs3746444) differs in frequency-matched 314 HCC patients and 407 controls by age and sex.

RESULTS

The groups' genotype distributions of miR-196a2 C > T and miR-499 C > T differed significantly (P < 0.01), both of them increased the risk of HCC in different dominant genetic models (P < 0.01); compared with individuals carrying one or neither of the unfavorable genotypes, individuals carrying both unfavorable genotypes (CT + CC) had a 3.11-fold higher HCC risk (95% confidence interval (CI), 1.89-5.09; P = 7.18 × 10-6). Moreover, the allele frequency of miR-499 C > T was significantly different between the two groups, and the HCC risk of carriers of the C allele was higher than that of carriers of the T allele (odds ratio, 1.53; 95% CI, 1.15-2.03; P = 0.003). Further, we found that the activated partial thromboplastin time (APTT) in HCC patients with miR-196a2 CC genotype was longer than patients with TT genotypes (P < 0.05), and HCC patients with miR-499 C allele had higher serum levels of direct bilirubin, globulin, γ-glutamyltranspeptidase, alkaline phosphatase, and lower serum cholinesterase (P < 0.05).

CONCLUSIONS

Our findings suggest that the SNPs in miR-196a2 C > T and miR-499 C > T confer HCC risk and that affect the clinical laboratory characteristics of HCC patients.

Association study of two inflammation-related polymorphisms with susceptibility to hepatocellular carcinoma: a meta-analysis

Background

Inflammation is a response of body tissues to injury or irritation. Small RNAs, such as miR-146a and miR-499, participate in various processes of tumorigenesis. A recent study indicates that inflammation and abnormal immune responses may promote malignant progression in cancer development, indicating that inflammation-related polymorphisms such as miR-146a rs2910164 and miR-499 rs3746444 are crucial. However, studies on the association of these two polymorphisms with hepatocellular carcinoma (HCC) are inconclusive and inconsistent. We aimed at accessing the combined result of reported studies and make a more precise estimate of the relationship.

Methods

Meta-analysis was performed on the associations between the miR-146a rs2910164 C > G and miR-499 rs3746444 T > C polymorphisms and hepatocellular carcinoma, using: allele contrast, dominant, and recessive models. A total of 12 studies(8 on miR-146a rs2910164 and 4 on miR-499 rs3746444) with three populations (Chinese, Korean, Turkish) were included in this study.

Results

Results show that both allele frequency and genotype distributions of miR-146a rs2910164 polymorphism are significantly associated with susceptibility to HCC (G versus C: OR = 1.153, 95% CI 1.083–1.228, P < 0.001; GC versus CC: OR = 1.165, 95% CI 1.054–1.286, P = 0.003; GG versus CC: OR = 1.361, 95% CI 1.192–1.553, P < 0.001; GG/GC versus CC: OR = 1.213, 95% CI 1.104–1.333, P < 0.001; GG versus GC/CC: OR = 1.210, 95% CI 1.080–1.356, P < 0.001). Our data suggest that people with G allele have a higher susceptibility to HCC as compared to those with C allele. However, meta-analysis failed to detect associations between miR-499 rs3746444 and HCC risk under each genetic model tested. Subgroup analysis showed that Chinese population with CC genotype are more vulnerable to HCC (OR = 2.171, 95% CI = 1.149–4.104, P = 0.017) than those with TT genotype.

Conclusions

We conclude that rs2910164 in miR-146a may confer susceptibility to HCC, especially in the Chinese population. No significant association was found between miR-499 rs3746444 and HCC, but subgroup study showed that subjects with CC genotype are more vulnerable to HCC than TT genotype in the Chinese population.

miRNAs affect the development of hepatocellular carcinoma via dysregulation of their biogenesis and expression

The pathogenesis of hepatocellular carcinoma (HCC) is not fully understood, which has affected the early diagnosis and treatment of HCC and the survival time of patients. MicroRNAs (miRNAs) are a class of evolutionarily conserved small, non-coding RNAs, which regulate the expression of various genes post-transcriptionally. Emerging evidence indicates that the key enzymes involved in the miRNA biosynthesis pathway and some tumor-specific miRNAs are widely deregulated or upregulated in HCC and closely associated with the occurrence and development of various cancers, including HCC. Early studies have shown that miRNAs have critical roles in HCC progression by targeting many critical protein-coding genes, thereby contributing to the promotion of cell proliferation; the avoidance of apoptosis, inducing via angiogenesis; and the activation of invasion and metastasis pathways. Experimental data indicate that discovery of increasing numbers of aberrantly expressed miRNAs has opened up a new field for investigating the molecular mechanism of HCC progression. In this review, we describe the current knowledge about the roles and validated targets of miRNAs in the above pathways that are known to be hallmarks of HCC, and we also describe the influence of genetic variations in miRNA biosynthesis and genes.

Overview and recent trends of systematic reviews and meta-analyses in hepatology

A systematic review (SR) is a research methodology that involves a comprehensive search for and analysis of relevant studies on a specific topic. A strict and objective research process is conducted that comprises a systematic and comprehensive literature search in accordance with predetermined inclusion/exclusion criteria, and an assessment of the risk of bias of the selected literature. SRs require a multidisciplinary approach that necessitates cooperation with clinical experts, methodologists, other experts, and statisticians. A meta-analysis (MA) is a statistical method of quantitatively synthesizing data, where possible, from the primary literature selected for the SR. Review articles differ from SRs in that they lack a systematic methodology such as a literature search, selection of studies according to strict criteria, assessment of risk bias, and synthesis of the study results. The importance of evidence-based medicine (EBM) in the decision-making for public policy has recently been increasing thanks to the realization that it should be based on scientific research data. SRs and MAs are essential for EBM strategy and evidence-based clinical practice guidelines. This review addresses the current trends in SRs and MAs in the field of hepatology via a search of recently published articles in the Cochrane Library and Ovid-MEDLINE.

MicroRNA-148b expression is decreased in hepatocellular carcinoma and associated with prognosis

MicroRNAs are small non-coding RNA molecules that have been shown to regulate the expression of genes linked to cancer. MicroRNA-148a (miR-148a) has recently been found to be involved in many critical processes in human malignancies. The present study is to clarify the expression pattern and prognostic role of miR-148b in human hepatocellular carcinoma (HCC). The expression of miR-148b was detected in 156 cases of HCC and 36 cases of normal control specimens by real-time PCR. Results showed that miR-148b expression was significantly decreased in HCC compared with that in normal control. It was also demonstrated that aberrant miR-148b expression was associated with vein invasion and TNM stage of HCC. Kaplan-Meier analysis showed that decreased miR-148b expression was associated with poor overall survival of patients. A multivariate survival analysis also indicated that miR-148b could be an independent prognostic marker. These results proved that miR-148b expression was decreased in HCC and associated with tumor invasion and progression. The present study also provides the first evidence that miR-148b could be an independent prognostic factor for patients with HCC, indicating the potential role of miR-148b as a prognostic marker in clinical practice, and the inhibition of miR-148b may even become a new therapeutic method for the treatment of HCC.

Association between two common polymorphisms and risk of hepatocellular carcinoma: evidence from an updated meta-analysis

Background. Recent studies suggested that two common polymorphisms, miR-146a G>C and miR-196a2 C>T, may be associated with individual susceptibility to hepatocellular carcinoma (HCC). However, the results remain conflicting rather than conclusive. Object. The aim of this study was to assess the association between miR-146a G>C and miR-196a2 C>T polymorphisms and the risk of HCC. Methods. A meta-analysis of 17 studies (10938 cases and 11967 controls) was performed. Odds ratios and 95% confidence intervals were used to evaluate the strength of the association. Results. For miR-146a G>C, the variant genotypes were associated with a decreased risk of HCC (CC versus GG: OR = 0.780 and 95% CI 0.700–0.869; GC/CC versus GG: OR = 0.865 and 95% CI 0.787–0.952; CC versus GC/GG: OR = 0.835 and 95% CI 0.774–0.901). For miR-196a2 C>T, significant association was also observed (TT versus CC: OR = 0.783, 95% CI: 0.649–0.943, and P = 0.010; CT versus CC: OR = 0.831, 95% CI 0.714–0.967, and P = 0.017; CT/TT versus CC: OR = 0.817, 95% CI 0.703–0.949, and P = 0.008). Conclusion. The two common polymorphisms miR-146a G>C and miR-196a2 C>T were associated with decreased HCC susceptibility, especially in Asian population.

miR-146a G>C polymorphisms and risk of hepatocellular carcinoma in a Chinese population

MicroRNAs (miRNAs) are thought to have a role in cancer development. We investigated the association among miR-146a G>C genetic variations, hepatitis B (HBV), and C (HCV) infection, and risk of hepatocellular carcinoma (HCC). Unconditional logistical regression analysis suggested that the miR-146a GG genotype and G allele carried a 2.10- (95 % confidence interval (CI)=1.03-4.37) and 1.42-fold (95 % CI=1.07-1.92) increased HCC risk, respectively. HBV-positive subjects carrying the miR-146a GG genotype (odds ratio (OR)=2.95, 95 % CI=1.31-6.81) and G allele (OR=1.65, 95 % CI=1.15-2.58) had an increased risk of HCC. However, the miR-146a GG genotype and G allele did not carry a significantly enhanced risk of HCC in either hepatitis-negative or HCV-infected subjects. miR-146a G>C polymorphisms appear to influence susceptibility to HCC, especially in HBV-infected patients.

The NQO1 C609T polymorphism and hepatocellular carcinoma risk

NAD(P)H quinine oxidoreductase 1 (NQO1) enzyme plays a crucial role in the protection against oxidative stress. The polymorphism of NQO1 C609T has been implicated in the development of hepatocellular carcinoma (HCC). However, the findings were inconsistent due to different ethnicity, sample size, and source of controls in individual studies. To better estimate the association of NQO1 C609T polymorphism with HCC risk, we performed a meta-analysis of all currently available studies on the susceptibility to HCC. The meta-analysis included three independent studies with a total of 1, 595 subjects. The association was assessed under five different gene models. The overall analysis suggested that the variant allele and genotypes were significantly related to increased risk of HCC (ORT vs. C = 1.47, 95 % CI 1.07-2.00, P OR = 0.016; ORTT vs. CC = 2.06, 95 % CI 1.06-3.98, P OR = 0.032; ORTC vs. CC = 1.33, 95 % CI 1.06-1.67, P OR = 0.012; ORTT + TC vs. CC = 1.46, 95 % CI 1.19-1.81, P OR < 0.001; ORTT vs. CC + TC = 1.62, 95 % CI 1.25-2.09, P OR < 0.001). Stratified analyses in Asians and hospital-based case-control studies further demonstrated the significant correlation. Sensitivity analysis confirmed the reliability of these findings. Our study firstly shows that individuals carrying the NQO1 C609T variant allele and genotypes are more susceptible to HCC, particularly for Asians.

Association between microRNA polymorphisms and cancer risk based on the findings of 66 case-control studies

MicroRNAs (miRNAs) are small non-coding RNA molecules, which participate in diverse biological processes and may regulate tumor suppressor genes or oncogenes. Single nucleotide polymorphisms (SNPs) in miRNA may contribute to diverse functional consequences, including cancer development, by altering miRNA expression. Numerous studies have shown the association between miRNA SNPs and cancer risk; however, the results are generally debatable and inconclusive, mainly due to limited statistical power. To assess the relationship between the five most common SNPs (miR-146a rs2910164, miR-196a2 rs11614913, miR-499 rs3746444, miR-149 rs2292832, and miR-27a rs895919) and the risk cancer development, we performed a meta-analysis of 66 published case-control studies. Crude odds ratios at 95% confidence intervals were used to investigate the strength of the association. No association was observed between rs2910164 and cancer risk in the overall group. However, in stratified analysis, we found that either the rs2910164 C allele or the CC genotype was protective against bladder cancer, prostate cancer, cervical cancer, and colorectal cancer, whereas it was a risk factor for papillary thyroid carcinoma and squamous cell carcinoma of the head and neck (SCCHN). Further, rs11614913 was found to be significantly associated with decreased cancer risk, in particular, for bladder cancer, gastric cancer, and SCCHN. For miR-499, a significant association was found between the rs3746444 polymorphism and cancer risk in pooled analysis. In subgroup analysis, similar results were mainly observed for breast cancer. Finally, no association was found between rs2292832 and rs895919 polymorphisms and cancer risk in the overall group and in stratified analysis. In summary, miR-196a2 rs11614913, miR-146a rs2910164, and miR-499 rs3746444 are risk factors for cancer development, whereas mir-149 rs2292832 and miR-27a rs895919 are not associated with cancer risk.

Associations of miR-499 and miR-34b/c Polymorphisms with Susceptibility to Hepatocellular Carcinoma: An Evidence-Based Evaluation

Background. Hepatocellular carcinoma (HCC) represents the sixth common cancer in the world. Single nucleotide polymorphisms (SNPs) in microRNA genes may be associated with susceptibility to HCC. Recently, several studies have reported possible associations of SNPs miR-499 T>C rs3746444 and miR-34b/c T>C rs4938723 with the risk of HCC. However the results are inconsistent and inconclusive. In this present study, we conducted a meta-analysis to comprehensively evaluate potential associations between the two SNPs and HCC susceptibility. Methods. Through a systematic literature search, 8-case-control studies involving 5464 subjects were identified and included in this meta-analysis. The association between the two common SNPs and HCC risk was estimated by pooled odds ratios (ORs) and 95% confidence intervals (95% CIs). Our results showed no significant association between rs3746444 and susceptibility to HCC, whereas variant genotypes of rs4938723 were associated with increased HCC risk in allele frequency model and heterozygous model (C versus T, OR = 1.11, 95% CI: 1.01-1.23, P = 0.04; TC versus TT, OR = 1.19, 95% CI: 1.03-1.37, P = 0.02). Conclusions. The current evidence did not support association between rs3746444 and HCC risk. SNP rs4938723 may be associated with susceptibility to HCC. Further well-designed studies are required to clarify the relationships between the two SNPs and HCC risk.