Genetic Variants in pre-miR-146a, pre-miR-499, pre-miR-125a, pre-miR-605, and pri-miR-182 Are Associated with Breast Cancer Susceptibility in a South American Population

Prospective Functions of miRNA Variants May Predict Breast Cancer Among Saudi Females

Background Growing knowledge supports the importance of microRNAs (miRNAs) in modulating the initiation and development of breast cancer (BC) and underlying mechanisms. BC is a significant public health in females worldwide, where it remains the leading cause of death among Saudi females. Here, we evaluate the susceptibility of the miRNA genetic variants to the risk of BC in Saudi females. Methods One hundred fifty-four females, including 76 females diagnosed with BC and 78 healthy controls, were analyzed using TaqMan™ (Thermo Fischer Scientific, Waltham, MA) genotyping assays for the miR-196a2 rs11614913 C>T, miR-146a rs2910164 C>G, and miR-499 rs3746444 A>G. We utilized the SNPStats software (https://www.snpstats.net) (Institut Català d'Oncologia, Barcelona, Spain) to choose the best interactive inheritance model for the examined miRNAs. Results The examined miRNA single-nucleotide polymorphisms (SNPs) showed no clear association with the risk of BC (P > 0.05). As for genotypic distributions, significant associations were found for the rs2910164 SNP in most interactive models of inheritance: 2.50 (95% confidence interval {CI}, 1.2-5.17; P = 0.0135) in the codominant model, 2.34 (95% CI, 1.11-4.8; P = 0.0197) in the dominant model, and 2.40 (95% CI, 1.22-4.73; P = 0.0113) in overdominant model. The rs2910164 C/G heterozygosity showed overexpression in cases compared to controls (73.7% versus 53.9%; chi-squared (χ2) = 6.5; P = 0.0109), but the homozygous rs2910164 G/G showed a significant protective effect (21.1% versus 38.5%; χ2 = 17.4; P = 0.019). The heterozygosity did not affect the risk to the BC in the two miRNAs (rs11614913 C>T and rs3746444 A>G). Conclusion Despite lacking associations with the examined miRNAs, the heterozygous genotype rs2910164 C/G can identify at-risk females. More studies should be replicated using a panel of miRNA genes to discover significant associations with the risk of BC.

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.

Genetic Polymorphism rs6505162 in MicroRNA-423 May Not Be Associated with Susceptibility of Breast Cancer: A Systematic Review and Meta-Analysis

Background

MicroRNA-423 (miR-423) rs6505162 polymorphism is found to be associated with breast cancer (BC) risk. However, the results were inconsistent. This study meta-analyzed the literature on possible association between rs6505162 polymorphism and BC risk.

Methods

PubMed, Embase, Google Scholar, and the Chinese National Knowledge Infrastructure (CNKI) databases were systematically searched to identify relevant studies. Meta-analyses were performed to examine the association between rs6505162 polymorphism and BC.

Results

None of the five genetic models suggested a significant association between rs6505162 polymorphism and BC risk: allelic model, OR 1.02, 95% CI 0.18-1.28, P=0.85; recessive model, OR 0.99, 95% CI 0.72-1.38, P=0.97; dominant model, OR 0.93, 95% CI 0.72-1.21, P=0.60; homozygous model, OR 1.04, 95% CI 0.66-1.65, P=0.87; and heterozygous model, OR 1.07, 95% CI 0.90-1.28, P=0.45. Similar results were obtained in subgroup analyses of Asian, Chinese, and Caucasian patients.

Conclusion

The available evidence suggests no significant association between rs6505162 polymorphism and BC risk. These conclusions should be verified in large, well-designed studies.

Association between single-nucleotide polymorphisms in miRNA and breast cancer risk: an updated review

Breast cancer (BC), a heterogeneous, aggressive illness with high mortality, is essentially a genomic disease. While the high-penetrance genes BRCA1 and BRCA2 play important roles in tumorigenesis, moderate- and low-penetrance genes are also involved. Single-nucleotide polymorphisms (SNPs) in microRNA (miRNA) genes have recently been identified as BC risk factors. miRNA genes are currently classified as low-penetrance. SNPs are the most common variations in the human genome. While the role of miRNA SNPs in BC susceptibility has been studied extensively, results have been inconsistent. This review analyzes the results of association studies between miRNA SNPs and BC risk from countries around the world. We conclude that: (a) By continent, the largest proportion of studies to date were conducted in Asia (65.0 %) and the smallest proportion in Africa (1.8 %); (b) Association studies have been completed for 67 different SNPs; (c) 146a, 196a2, 499, 27a, and 423 are the most-studied miRNAs; (d) The SNPs rs2910164 (miRNA-146a), rs11614913 (miRNA-196a2), rs3746444 (miRNA-499) and rs6505162 (miRNA-423) were the most widely associated with increased BC risk; (e) The majority of studies had small samples, which may affect the precision and power of the results; and (f) The effect of an SNP on BC risk depends on the ethnicity of the population. This review also discusses potential explanations for controversial findings.

Challenges of diagnostic genomics in Latin America

Cancer genome sequencing methods have now become essential for diagnostic purposes, for devising treatment strategies, and for monitoring disease regression and progression. However, access to these benefits has not permeated homogeneously throughout the world; certain regions, such as Latin America, have been slower at adopting these technologies in terms of their routine use, development and patient access. There are also differences among Latin American subregions with respect to their prioritized types of neoplasia and the drugs that are available and approved in them. An overview of the current situation, including the status of genomics for cancer diagnostics and efforts by type of cancer is presented. In addition, we discuss the perspective of initiatives, alliances, and educational/research programs that pledge to make cancer genomics diagnosis a reality for Latin American individuals' health.

Inhibition of breast cancer stem-like cells by a triterpenoid, ursolic acid, via activation of Wnt antagonist, sFRP4 and suppression of miRNA-499a-5p

Breast cancer, one of the leading causes of death in the world, has been largely considered to be drug resistant because of a small population of drug refractory cells, the cancer stem cells (CSCs). The CSCs are tightly regulated by self-renewal pathways such as the Wnt pathway, which is further regulated by a gamut of microRNAs. In this study, we investigated the effect of ursolic acid (UA), a natural triterpene, on breast CSCs enriched from breast cancer cell lines, MCF7, MDA-MB-231 and T47D and analysed the interplay of the Wnt inhibitor, sFRP4 and an miRNA, miR-499a-5p, in mediating the effect of UA. By using caspase 3/7, ROS, migration, TCF/LEF and CAM assays, overexpressing and inhibiting miR-499a-5p and NanoString PanCancer analysis, we observed that UA had significant anti-CSC ability. There was a link between UA and Wnt/β-catenin pathway wherein, Wnt was suppressed by upregulation of the antagonist, sFRP4. Furthermore, expression of the oncogenic miR-499a-5p was substantially diminished in CSCs after UA treatment. Notably, the axis by which miR-499a-5p acts is via the TCF/LEF machinery of the Wnt/β-catenin pathway. Our findings indicate for the first time that UA can target breast CSCs via Wnt by suppressing miR-499a-5p and upregulating the Wnt antagonist, sFRP4.

Genetic Variants in miRNAs Are Associated With Risk of Non-syndromic Tooth Agenesis

Non-syndromic tooth agenesis (NSTA) is one of the most common dental abnormalities. MiRNAs participated in the craniofacial and tooth development. Therefore, single nucleotide polymorphisms (SNPs) in miRNA genes may contribute to the susceptibility of non-syndromic tooth agenesis. Here, a total of 625 non-syndromic tooth agenesis cases and 1,144 healthy controls were recruited, and four miRNA SNPs (miR-146a/rs2910164, miR-196a2/rs11614913, pre-miR-605/rs2043556, pre-miR-618/rs2682818) were genotyped by the TaqMan platform. Rs2043556 showed nominal associations with risk of non-syndromic tooth agenesis (P _Add = 0.021) in the overall analysis, as well as upper lateral incisor agenesis (P _Add = 0.047) and lower incisor agenesis (P _Add = 0.049) in the subgroup analysis. Notably, its significant association with upper canine agenesis was observed (P _Add = 0.0016). Rs2043556 affected the mature of miR-605-3p and miR-605-5p while dual-luciferase report analysis indicated that MDM2 was the binding target of miR-605-5p. Our study indicated that pre-miR-605 rs2043556 was associated with risk of non-syndromic tooth agenesis.

The emerging role of miRNA clusters in breast cancer progression

Micro RNAs (miRNAs) are small non-coding RNAs that are essential for regulation of gene expression of the target genes. Large number of miRNAs are organized into defined units known as miRNA clusters (MCs). The MCs consist of two or more than two miRNA encoding genes driven by a single promoter, transcribed together in the same orientation, that are not separated from each other by a transcription unit. Aberrant miRNA clusters expression is reported in breast cancer (BC), exhibiting both pro-tumorogenic and anti-tumorigenic role. Altered MCs expression facilitates to breast carcinogenesis by promoting the breast cells to acquire the various hallmarks of the cancer. Since miRNA clusters contain multiple miRNA encoding genes, targeting cluster may be more attractive than targeting individual miRNAs. Besides targeting dysregulated miRNA clusters in BC, studies have focused on the mechanism of action, and its contribution to the progression of the BC. The present review provides a comprehensive overview of dysregulated miRNA clusters and its role in the acquisition of cancer hallmarks in BC. More specifically, we have presented the regulation, differential expression, classification, targets, mechanism of action, and signaling pathways of miRNA clusters in BC. Additionally, we have also discussed the potential utility of the miRNA cluster as a diagnostic and prognostic indicator in BC.

microRNA-related single-nucleotide polymorphisms and breast cancer

Breast cancer, as the most common cancer in women which affects patients both mentally and physically, requires great attention in many areas and many levels as this cancer is known to be multifactorial. Single-stranded molecules called microRNAs with near 22 nucleotides are seen to act in central dogma of molecular biology by inhibiting the translation process; it is demonstrated that any alteration in their sequence especially single-nucleotide polymorphisms (SNPs) may lead into increasing the breast cancer risk. miR-SNPs are considered to be the potential biomarkers for early detection of breast cancer. As a result, this review documents the well-known miR-SNPs that are known to be associated with breast cancer. In this regard, two principals were discussed: (a) SNPs in the target genes of microRNAs and the alteration in gene expression due to this phenomenon; (b) changes based on the SNPs in the microRNA coding region and the impact on their interaction with target messenger RNA.

Associations of Single Nucleotide Polymorphism in miR-146a Gene with Susceptibility to Breast Cancer in the Iranian Female

BACKGROUND

MicroRNAs (miRNAs), short regulatory RNAs, function as negative regulators able to modulate gene expression. Just as other genetic variant, single nucleotide polymorphisms (SNPs) in miRNA genes, may have an impact on their expression and/or maturation and hence leading to different consequences in carcinogenesis. Accordingly, this study aimed to assess the frequency of miR-146a G/C (rs2910164) polymorphism and its association with susceptibility to breast cancer in Iranian women.

METHODS

We conducted a case-control study using Tetra ARMS polymerase chain reaction (Tetra ARMS PCR) method in 100 Iranian female participants (50 breast cancer patients and 50 controls). Besides, a number of sequenced samples were chosen to confirm the accuracy of genotyping by Tetra ARMA PCR. SPSS software was utilized for all statistical analyses. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were applied to analyze the association between the SNP frequency and breast cancer.

RESULTS

The frequency of genotypes for G/G, G/C, and C/C were 23 (46%), 26 (52%), and 1 (2%) among cases and 15 (30%), 33 (66%), and 2(4%) among controls, respectively. The results generated by the groups did not show any significant correlation between miR-146a G/C (rs2910164) polymorphism and breast cancer, either at genotype or allele levels (P>0.05). F-SNP-based in silico analysis indicated possible modifications in transcriptional regulations induced by miR-146a G/C (rs2910164) variations.

CONCLUSION

Overall, our results indicated no correlation between miR-146a G/C (rs2910164) polymorphism and genetic susceptibility to breast cancer in Iranian female populations. However, these findings need to be further confirmed by analyses of a larger number of cases.

Genetic Epidemiology in Latin America: Identifying Strong Genetic Proxies for Complex Disease Risk Factors

Epidemiology seeks to determine the causal effects of exposures on outcomes related to the health and wellbeing of populations. Observational studies, one of the most commonly used designs in epidemiology, can be biased due to confounding and reverse causation, which makes it difficult to establish causal relationships. In recent times, genetically informed methods, like Mendelian randomization (MR), have been developed in an attempt to overcome these disadvantages. MR relies on the association of genetic variants with outcomes of interest, where the genetic variants are proxies or instruments for modifiable exposures. Because genotypes are sorted independently and at random at the time of conception, they are less prone to confounding and reverse causation. Implementation of MR depends on, among other things, a strong association of the genetic variants with the exposure, which has usually been defined via genome-wide association studies (GWAS). Because GWAS have been most often carried out in European populations, the limited identification of strong instruments in other populations poses a major problem for the application of MR in Latin America. We suggest potential solutions that can be realized with the resources at hand and others that will have to wait for increased funding and access to technology.

A genetic variant of pri-miR-182 may impact the risk for the onset of multiple sclerosis in the Iranian population

BACKGROUND

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system affecting young adults. SNPs can be used as genetic biomarkers to identify disease-related genes such as MS. Moreover, SNPs can be considered as important determinants for an increased risk of autoimmune diseases such as MS. Studies have shown that miR-182 is of importance in Treg cell development and function as critical regulators in autoimmune disease. So far, no study has been conducted to investigate the association between rs4541843 polymorphism in pri-miR-182 and MS. In the present study, we assessed the frequency of rs4541843 different alleles and genotypes and their association with MS risk in Iranian population.

METHODS

The rs4541843 was genotyped in 81 patients with MS and 89 healthy subjects, using the PCR-RFLP method. The frequency of alleles and genotypes and the association of this polymorphism with MS risk and the gender of the patients was then statistically analyzed.

RESULTS

Statistical analysis showed the protective role of AA genotype against MS risk (P = .031, OR = 0.348) while there was no significance correlation between the frequency of rs4541843 different alleles and the other genotypes.

CONCLUSION

Our findings illustrated that the pri-miR-182 rs4541843 G>A polymorphism is associated with the risk of MS in Isfahan population. However, additional large-scale association studies in various ethnicities and more molecular studies are necessary to elaborate our findings.

Association between MIR499A rs3746444 polymorphism and breast cancer susceptibility: a meta-analysis

Numerous studies have investigated the association of MIR499A rs3746444 polymorphism with breast cancer susceptibility, but the results have been inconsistent. In this work, we performed a meta-analysis to obtain a more reliable estimate of the association between the polymorphism and susceptibility to breast cancer. A comprehensive literature search was conducted on PubMed, Scopus, Web of Science (WoS), China National Knowledge Infrastructure (CNKI), VIP and Wanfang databases up to January 2020. A total of 14 studies involving 6,797 cases and 8,534 controls were included for analysis under five genetic models: homozygous (GG vs. AA), heterozygous (AG vs. AA), dominant (AG + GG vs. AA), recessive (GG vs. AA + AG) and allele (G vs. A). A statistically significant association was observed between the polymorphism and an increased breast cancer susceptibility under all genetic models (homozygous, OR = 1.33, 95% CI = 1.03-1.71, P = 0.03; heterozygous, OR = 1.08, 95% CI = 1.00-1.16, P = 0.04; dominant, OR = 1.15, 95% CI = 1.02-1.30; P = 0.03; recessive, OR = 1.35, 95% CI = 1.06-1.72, P = 0.01; allele, OR = 1.12, 95% CI = 1.00-1.26, P = 0.04). Subgroup analysis based on ethnicity suggested that significant association was present only among Asians, but not Caucasians. In conclusion, MIR499A rs3746444 polymorphism was significantly associated with breast cancer susceptibility among Asians, suggesting its potential use as a genetic risk marker in this population.

A genetic variant in the flanking region of miR-182 could decrease the susceptibility to the breast cancer risk in the iranian population

Breast cancer is one of the most malignant tumors in the world. It is, in fact, the second leading cause of cancer death in women. Recent research has identified the role of miR-182 in this disease as an oncogene agent. In this study, the association of rs4541843 in the flanking region of the miR-182 sequence with the susceptibility to breast cancer risk has been studied in the Iranian population. By using the PCR_RFLP, the genotype rs4541843 was determined in 161 patients and 164 control subjects. The genotypes of the individuals were analyzed statistically to find the association between rs4541843 and the breast cancer incidence and its pathological characteristics. The results revealed that due to the dominance of the G allele, the frequency of GG + AG genotypes, as compared with AA, had a significant correlation with the incidence of this disease in controls and cases (P = 0.022; OR = 0.523). Moreover, the genotypes AG and AA could significantly decrease the susceptibility to the breast cancer risk; also in the presence of the A allele (OR, 0.565; P = 0.015), the incidence of the disease could be decreased. Our results indicated that this SNP was associated with the breast cancer risk of the Iranian population. We suppose that rs4541843 may influence the processing of the mature miRNA by affecting the cleavage of Drosha. Therefore, this SNP can be considered as a candidate genetic marker for the susceptibility to breast cancer in the Iranian women.

Phase I study of the mTOR inhibitor everolimus in combination with the histone deacetylase inhibitor panobinostat in patients with advanced clear cell renal cell carcinoma

Background Preclinical studies suggested synergistic anti-tumor activity when pairing mTOR inhibitors with histone deacetylase (HDAC) inhibitors. We completed a phase I, dose-finding trial for the mTOR inhibitor everolimus combined with the HDAC inhibitor panobinostat in advanced clear cell renal cell carcinoma (ccRCC) patients. We additionally investigated expression of microRNA 605 (miR-605) in serum samples obtained from trial participants. Patients and Methods Twenty-one patients completed our single institution, non-randomized, open-label, dose-escalation phase 1 trial. miR-605 levels were measured at cycle 1/day 1 (C1D1) and C2D1. Delta Ct method was utilized to evaluate miR-605 expression using U6B as an endogenous control. Results There were 3 dosing-limiting toxicities (DLTs): grade 4 thrombocytopenia (n = 1), grade 3 thrombocytopenia (n = 1), and grade 3 neutropenia (n = 1). Everolimus 5 mg PO daily and panobinostat 10 mg PO 3 times weekly (weeks 1 and 2) given in 21-day cycles was the recommended phase II dosing based on their maximum tolerated dose. The 6-month progression-free survival was 31% with a median of 4.1 months (95% confidence internal; 2.0-7.1). There was higher baseline expression of miR-605 in patients with progressive disease (PD) vs those with stable disease (SD) (p = 0.0112). PD patients' miR-605 levels decreased after the 1st cycle (p = 0.0245), whereas SD patients' miR-605 levels increased (p = 0.0179). Conclusion A safe and tolerable dosing regimen was established for combination everolimus/panobinostat therapy with myelosuppression as the major DLT. This therapeutic pairing did not appear to improve clinical outcomes in our group of patients with advanced ccRCC. There was differential expression of miR-605 that correlated with treatment response. Clinical trial information: NCT01582009.

Evidences from a Systematic Review and Meta-Analysis Unveil the Role of MiRNA Polymorphisms in the Predisposition to Female Neoplasms

Breast (BCa) and gynecological (GCa) cancers constitute a group of female neoplasms that has a worldwide significant contribution to cancer morbidity and mortality. Evidence suggests that polymorphisms influencing miRNA function can provide useful information towards predicting the risk of female neoplasms. Inconsistent findings in the literature should be detected and resolved to facilitate the genetic screening of miRNA polymorphisms, even during childhood or adolescence, and their use as predictors of future malignancies. This study represents a comprehensive systematic review and meta-analysis of the association between miRNA polymorphisms and the risk of female neoplasms. Meta-analysis was performed by pooling odds-ratios (ORs) and generalized ORs while using a random-effects model for 15 miRNA polymorphisms. The results suggest that miR-146a rs2910164 is implicated in the susceptibility to GCa. Moreover, miR-196a2 rs11614913-T had a moderate protective effect against female neoplasms, especially GCa, in Asians but not in Caucasians. MiR-27a rs895819-G might pose a protective effect against BCa among Caucasians. MiR-499 rs3746444-C may slightly increase the risk of female neoplasms, especially BCa. MiR-124 rs531564-G may be associated with a lower risk of female neoplasms. The current evidences do not support the association of the remaining polymorphisms and the risk of female neoplasms.

Lack of Association between miR-605 rs2043556 Polymorphism and Overall Cancer Risk: A Meta-analysis of Case-control Studies

Growing evidence propose an association between miRNA polymorphisms and cancer susceptibility. This study aimed to examine the impact of miR-605 rs2043556 polymorphism on cancer risk through a meta-analysis based on 3198 cancer cases and 4943 controls. Eligible studies were retrieved by searching Web of Science, PubMed, Scopus, and Google Scholar databases up to August 27, 2018. The pooled Odds Ratios (ORs) with 95% Confidence Intervals (CIs) were calculated using a random-effect model to estimate the strength of association between rs2043556 variant of miR-605 and cancer risk. Overall, no significant association was found between miR-605 rs2043556 polymorphism and cancer risk in heterozygous codominant (OR=0.93, 95% CI=0.76-1.13, p=0.44, AG vs. AA), homozygous codominant (OR=1.01, 95%CI=0.78-1.30, p=0.94, GG vs. AA), dominant (OR=0.95, 95% CI=0.79-1.13, p=0.55, AG+GG vs. AA), recessive (OR=1.07, 95%CI=0.84-1.38, p=0.57, GG vs. AG+AA), overdominant (OR=0.93, 95% CI=0.76-1.12, p=0.43, AG vs. GG+AA), and allele (OR=0.98, 95% CI=0.87-1.10, p=0.73, G vs. A) genetic models tested. Stratified analysis by cancer type revealed that the rs2043556 variant was not associated with digestive tract cancer, breast cancer, gastric cancer as well as lung cancer. Taken together, the findings of this meta-analysis did not support an association between miR-605 rs2043556 polymorphism and cancer susceptibility.

MicroRNA-296, a suppressor non-coding RNA, downregulates SGLT2 expression in lung cancer

Non-small cell lung cancer (NSCLC) is one of the most common types of cancer worldwide and has the highest mortality rate in China. MicroRNAs (miRNAs or miRs) are involved in tumorigenesis and their important role in cancer is becoming increasingly apparent. The expression of miR‑296‑5p in particular has been shown to be significantly downregulated in lung cancer. Sodium-glucose co-transporter-2 [SGLT2, also known as solute carrier family 5 member 2 (SLC5A2)] is an oncogene that promotes tumorigenesis. In this study, we aimed to determine the role of miR‑296‑5p in lung cancer and whether this involves the targeting of SGLT2. For this purpose, we examined miR‑296‑5p and SGLT2 expression in human lung cancer samples and cell lines by RT-qPCR and western blot analysis. In addition, the data analysis website TCGA was used for survival analysis with respect to SGLT2 expression. The effects of miR‑296‑5p were also examined on cell proliferation and cell cycle progression using respective assays. The results demonstrate that miR‑296‑5p is significantly downregulated in NSCLC tissues. Additionally, it is demonstrated that SGLT2 is directly targeted by miR‑296‑5p. Furthermore, our data reveal that the knockdown of SGLT2 using siRNA inhibits cell proliferation and impedes cell cycle progression. Collectively, data suggest that miR‑296‑5p not only inhibits NSCLC by downregulating SGLT2 expression, but also acts as a novel regulator of aberrant lung cancer cells to limit lung cancer progression.