Five Common Functional Polymorphisms inmicroRNAsand Susceptibility to Breast Cancer: An Updated Meta-Analysis

Single Nucleotide Polymorphisms in microRNA Genes and Colorectal Cancer Risk and Prognosis

There is growing interest in single nucleotide polymorphisms (SNPs) in the genes of microRNAs (miRNAs), which could be associated with susceptibility to colorectal cancer (CRC) and therefore for prognosis of the disease and/or treatment response. Moreover, these miRNAs-SNPs could serve as new, low-invasive biomarkers for early detection of CRC. In the present article, we performed a thorough review of different SNPs, which were investigated for a correlation with the CRC risk, prognosis, and treatment response. We also analyzed the results from different meta-analyses and the possible reasons for reported contradictory findings, especially when different research groups investigated the same SNP in a gene for a particular miRNA. This illustrates the need for more case-control studies involving participants with different ethnic backgrounds. According to our review, three miRNAs-SNPs-miR-146a rs2910164, miR-27a rs895819 and miR-608 rs4919510-appear as promising prognostic, diagnostic and predictive biomarkers for CRC, respectively.

Associations between genetic variations in microRNA and myocardial infarction susceptibility: a meta-analysis and systematic review

BACKGROUND

Current genetic association studies have reported conflicting results regarding the association between miRNA polymorphisms and myocardial infarction (MI) risk METHODS: Relevant studies were retrieved from the PubMed, EMBASE, ISI Web of Science, and Scopus databases. Eligible studies determining the association between miRNA polymorphisms and MI susceptibility were included and a meta-analysis was performed to quantify the associations between miRNA polymorphisms and MI risk.

RESULTS

A total of eight studies with 2507 MI patients and 3796 healthy controls were included, dealing with nine miRNA genes containing 11 different loci, including miR-149 (rs71428439 and rs2292832), miR-126 (rs4636297 and rs1140713), miR-146a (rs2910164), miR-218 (rs11134527), miR-196a2 (rs11614913), miR-499 (rs3746444), miR-27a (rs895819), miR-26a‑1 (rs7372209), and miR-100 (rs1834306). miR-146a rs2910164 and miR-499 rs3746444 were determined to have a significant association with MI susceptibility, a finding that was supported by the meta-analysis (rs2910164: GG/CC, odds ratio [OR]: 1.40, 95% confidence interval [95% CI]: 1.05-1.74, p < 0.001; rs3746444: AA + AG/GG, OR = 2.04, 95% CI: 1.37-2.70, p < 0.001). Limited or conflicting data were found for the relationship between the other miRNA polymorphisms (rs71428439, rs4636297, rs1140713, rs11134527, rs11614913, rs895819, rs7372209, rs1834306, rs2292832) and MI risk.

CONCLUSION

There was a significant association between rs2910164 and rs3746444 and MI susceptibility. Further studies are required to investigate the role of miRNA polymorphisms in MI risk.

miR-155 promotes proliferation and epithelial-mesenchymal transition of MCF-7 cells

Breast cancer (BC) is the second leading cause of cancer-associated deaths among women worldwide. Increasing evidence has indicated that microRNAs (miRNAs) have demonstrated great potential for improving the diagnosis and therapy for BC. In the present study, miRNA-155 was detected in human BC tissues using reverse transcription-quantitative (RT-q)PCR. RT-qPCR and western blot assays were used to analyze the levels of transforming growth factor β receptor type II (TGFBR2) in human BC tissues. MCF-7 cells were cultured and treated with miR-155 inhibitor and an MTT assay was performed to determine the role of miR-155 on the proliferation of MCF-7 cells. Subsequently, TGFBR2 and epithelial-mesenchymal transition (EMT)-associated molecules were analyzed using RT-qPCR and western blot assays. The direct binding of miR-155 to TGFBR2 was validated using a dual luciferase assay. Higher levels of miR-155 and lower levels of TGFBR2 were expressed in human BC tissues compared with paired normal tissues. Furthermore, the expression levels of miR-155 were associated with the tumor size, TNM stage and metastasis status of BC. Transfection of MCF-7 cells with miR-155 inhibitors resulted in reduced cell proliferation and suppressed the EMT process, characterized by upregulated expression of the epithelial markers, E-cadherin and CK18, and downregulated expression of mesenchymal markers, fibronectin and smooth muscle actin α. Transfection of a miR-155 inhibitor also resulted in increased expression of TGFBR2, and miR-155 may have regulated TGFBR2 through direct binding to the 3'untranslated region of TGFBR2 as determined using a dual-luciferase assay. Based on the results of the present study, miR-155 may serve as a novel diagnostic biomarker and therapeutic target for patients with BC.

Association between miR-27a rs895819 polymorphism and breast cancer susceptibility: Evidence based on 6118 cases and 7042 controls

BACKGROUND

Polymorphism in miR-27a rs895819 has been associated with breast cancer (BC) risk, but studies have reported inconsistent results. This meta-analysis investigated the possible association between miR-27a rs895819 polymorphism and BC risk.

METHODS

PubMed, EMBASE, Google Scholar, and the Chinese National Knowledge Infrastructure (CNKI) databases were systematically searched to identify relevant studies in English and Chinese. Meta-analyses were performed to examine the association between miR-27a rs895819 and BC susceptibility.

RESULTS

A total of 16 case-control studies involving 6118 cases and 7042 controls were included. Analysis using five genetic models suggested no significant association between miR-27a rs895819 polymorphism and BC risk in the total population, or specifically in Asian or Chinese subpopulations. In the Caucasian subpopulation, however, the G-allele and AG genotype at rs895819 were significantly associated with decreased BC risk according to the allelic model (OR 0.90, 95% CI 0.84-0.97, P = .004) and heterozygous model (OR 0.89, 95% CI 0.81-089, P = .02), while the wild-type AA genotype was significantly associated with increased BC risk according to the dominant model (OR 1.13, 95% CI 1.03-1.24, P = .007).

CONCLUSION

These results indicate that among Caucasians, the wild-type AA genotype at rs895819 may confer increased susceptibility to BC, while the G-allele and AG genotype may be protective factors. These conclusions should be verified in large, well-designed studies.

Association between Genetic Polymorphisms of miR-1307, miR- 1269, miR-3117 and Breast Cancer Risk in a Sample of South East Iranian Women

INTRODUCTION

MicroRNAs (miRNAs) play an essential role in the susceptibility and development of cancer cells.

OBJECTIVE

Examining the dependency of breast cancer risk with genetic polymorphisms of miR-1307, miR-1269, and miR-3117 in a sample of Iranian women (southeast region).

METHODS

The case-control study consisted of 520 individuals (260 diagnosed BC patients, 260 healthy individuals). The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used for genotyping of miR-1307 rs7911488, miR-1269 rs73239138, and miR-3117 (rs4655646 and rs7512692) polymorphisms.

RESULTS AND CONCLUSION

This study provided evidence that miR-1307 rs7911488 polymorphism significantly reduced the risk of BC in heterozygous AG genotype, as well as dominant (AG+GG) genotype and G allele. A significant correlation was found between dominant (AA+AG) genotype, the A allele and protection against BC due to miR-1269 rs73239138 in the sample of study. In contrast, our findings suggested that AG genotype and G allele of miR-3117 rs4655646 polymorphism could increase BC's susceptibility among the southeastern Iranian females. The miR-3117 rs7512692 variant also increased the risk of BC in codominant, dominant and recessive models, as well as the T allele. The possible dependency of miR-1307, miR-1269, and miR-3117 variants with patients' clinicopathological characteristics and BC was also studied. It was concluded that there is a correlation between miR-3117 rs7512692 variant and tumor grade (p=0.031); also, a correlation between miR-1269 rs73239138 variant and progesterone receptor status (p=0.006). The current investigation revealed that miR-1307, miR-1269, and miR-3117 polymorphisms might play a crucial role in the Iranian population's vulnerability to BC.<br />.

The Relationship between Pre-miR-3131 3-bp Insertion/Deletion Polymorphism and Susceptibility and Clinicopathological Characteristics of Patients with Breast Cancer

Aims

This study aimed at examining the effect of 3-bp pre-miR-3131 insertion/deletion (ins/del) polymorphism on Breast Cancer (BC) risk.

Objectives

Totally 403 women including 199 BC patients and 204 women who have no cancer were included in this case-control study. Genotyping of miR-3131 3-bp ins/del polymorphism was performed by mismatch PCR-RFLP method.

Methods

The findings expressed that the pre-miR-3131 3-bp ins/del variant was not related to the risk of BC in all genetic tested models. While, the ins/del genotype was related to late onset BC (OR=2.53, 95%CI=1.27-4.84, p=0.008).

Results

Pooled results from the meta-analysis indicated to that the pre-miR-3131 ins/del is related to with an increased risk of cancer in heterozygous (OR=1.26, 95%CI=1.06-1.51, p=0.01), dominant (OR=1.33, 95%CI=1.14-1.54, p=0.0002), and allele (OR=1.24, 95%CI=1.06-1.45, p=0.006) genetics models.

Conclusion

It is concluded that, our findings did not support a relationship between pre-miR-3131 ins/del polymorphism and the risk of BC. While, this variant was significantly related to late onset BC. Combined results of this study with previous studies indicated that this polymorphism increased the risk of cancer. More studies in a study with larger population with variety of ethnicities are required to verify our findings.