Association of microRNA-196a-2 gene polymorphism with gastric cancer risk in a Chinese population

Noncoding RNA mutations in cancer

Cancer is driven by both germline and somatic genetic changes. Efforts have been devoted to characterizing essential genetic variations in cancer initiation and development. Most attention has been given to mutations in protein-coding genes and associated regulatory elements such as promoters and enhancers. The development of sequencing technologies and in silico and experimental methods has allowed further exploration of cancer predisposition variants and important somatic mutations in noncoding RNAs, mainly for long noncoding RNAs and microRNAs. Association studies including GWAS have revealed hereditary variations including SNPs and indels in lncRNA or miRNA genes and regulatory regions. These mutations altered RNA secondary structures, expression levels, and target recognition and then conferred cancer predisposition to carriers. Whole-exome/genome sequencing comparing cancer and normal tissues has revealed important somatic mutations in noncoding RNA genes. Mutation hotspots and somatic copy number alterations have been identified in various tumor-associated noncoding RNAs. Increasing focus and effort have been devoted to studying the noncoding region of the genome. The complex genetic network of cancer initiation is being unveiled. This article is categorized under: RNA in Disease and Development > RNA in Disease.

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.

Functional Variants in MicroRNAs (rs895819, rs11614913 and rs2910164) Are Associated with Susceptibility and Clinicopathological Features in Mexican Patients with Colorectal Cancer

BACKGROUND

miRNAs are non-coding RNAs participating actively in the post-translational regulation of oncogenes, tumor suppressor, and DNA repair genes implicated in colorectal cancer (CRC). This study aims to examine the association of the variants miR-27a (rs895819 A>G), miR-196a2 (rs11614913 T>G) and miR-146a (rs2910164 C>G) in Mexican CRC patients.

METHODS

DNA samples from 183 patients and 186 healthy Mexican subjects were analyzed. Variants were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology. Association was calculated by the odds ratio (OR) and adjusted by the Bonferroni test.

RESULTS

Patients carrying the G/G genotype of the rs895819 variant in the miR-27a gene showed an increased risk of CRC (19% vs 12%, P=0.013). A similar tendency was noticed for patients younger than 50 years carrying A/G (48% vs 41%, P=0.014). The A/G genotype in TNM stages I+II (55.7% vs 40.8%, P=0.011) and tumor location in the colon (69.5 vs 40.8%, P=0.001) were also increased. For the variant rs11614913 of the miR-196a2 gene, carriers of the C/C genotype showed an increased risk of CRC (32% vs 22%, P=0.009). This genotype was more frequent in TNM stage III+IV (36.8% vs 22.5%, P=0.007) and the tumor had a more recurrent location in the rectum (31.6% vs 22.5%, P=0.013). The rs2910164 variant of the miR-146a gene was found to have no significant risk associations.

CONCLUSION

Our results reveal that the rs895819 variant in miR-27a and rs11614913 in miR-196a2 have a substantial impact on the development of CRC.

Functional gene polymorphisms and expression alteration of selected microRNAs and the risk of various gastric lesions in Helicobacter pylori-related gastric diseases

Background: Helicobacter pylori (Hp) persistent infection is an important pathogenic factor for a series of chronic gastric diseases from chronic gastritis to gastric cancer. Genetic and epigenetic abnormalities of microRNAs may play a vital role in the pathological evolution of gastric mucosa in Helicobacter pylori-related gastric diseases (HPGD). This study aimed to investigate the relationship between miR-146a, miR-196a2, miR-149, miR-499 and miR-27a gene single nucleotide polymorphisms (SNPs) and their expressions with pathological changes in gastric mucosa, and to further analyze the interactions between SNPs and Hp. Methods: Subjects in this study included patients diagnosed with HPGD and healthy controls. MiR-146a rs2910164, miR-196a2 rs11614913, miR-149 rs2292832, miR-499 rs3746444 and miR-27a rs895819 were genotyped by direct sequencing. Fluorescence quantitative PCR was used to detect microRNA expressions. Gene-gene and gene-environment interactions were evaluated by multifactor dimensionality reduction (MDR) method. Results: we found that frequency distribution of miR-196a2 rs11614913 CT genotype in gastric precancerous lesion (GPL) group and gastric cancer (GC) group was significantly higher than normal control (NOR) group [adjusted OR = 6.16, 95%CI (1.46-26.03); adjusted OR = 11.83, 95%CI (1.65-84.72), respectively]. CT genotype and C allele of miR-27a rs895819 were associated with increased risk of GC [adjusted OR = 10.14, 95%CI (2.25-45.77); adjusted OR = 3.71, 95%CI(1.46-9.44), respectively]. The MDR analysis results showed that the interaction between miR-196a2 rs11614913 and Hp was associated with the risk of GPL (p = 0.004). Meanwhile, the expression level of miR-196a2 in GC group was significantly higher than NOR, chronic inflammation (CI) and early precancerous lesion (EPL) groups among Hp-positive subjects. And expressions of miR-499 and miR-27a in GC group were both higher than EPL group. Also, miR-27a expression in GC group was higher than CI and gastric atrophy (GA) groups. Conclusion: miR-196a2 rs11614913 and miR-27a rs895819 may affect the genetic susceptibility to GPL or GC. MiR-196a2 rs11614913 and Hp have a synergistic effect in the occurrence and development of GPL. The up-regulation of miR-499, miR-196a2 and miR-27a expression caused by Hp infection may be an important mechanism of gastric carcinogenesis.

The genetic polymorphisms in the SP4 gene and the risk of gastric cancer

Aim: Gastric cancer (GC) is the leading cause of cancer death, and is associated with host genetic factors. This study aimed to determine the impact of SP4 polymorphisms on GC. Materials & methods: Four hundred and eighty-nine GC patients and 481 healthy subjects were recruited. The association between single nucleotide polymorphisms and GC risk was investigated by logistic regression analysis. Results: It was observed that rs39302 and rs7811417 were related to a decreased GC risk. Stratified analyses showed that rs39302 decreased GC susceptibility at ages ≤60 years, in men, GC patients who had previously smoked and drank. rs7811417 had a risk-decreasing impact on the patients aged ≤60 years, in men, GC patients who were nonsmoking and nondrinking. rs35929923 decreased the GC risk of patients in grade III-IV and the lymph node metastasis subgroup. Conclusion: SP4 gene polymorphisms are associated with GC risk.

Signatures of genetic variation in human microRNAs point to processes of positive selection and population-specific disease risks

The occurrence of natural variation in human microRNAs has been the focus of numerous studies during the last 20 years. Most of them have been focused on the role of specific mutations in disease, while a minor proportion seek to analyse microRNA diversity in the genomes of human populations. We analyse the latest human microRNA annotations in the light of the most updated catalogue of genetic variation provided by the 1000 Genomes Project. By means of the in silico analysis of microRNA genetic variation we show that the level of evolutionary constraint of these sequences is governed by the interplay of different factors, like their evolutionary age or genomic location. The role of mutations in the shaping of microRNA-driven regulatory interactions is emphasized with the acknowledgement that, while the whole microRNA sequence is highly conserved, the seed region shows a pattern of higher genetic diversity that appears to be caused by the dramatic frequency shifts of a fraction of human microRNAs. We highlight the participation of these microRNAs in population-specific processes by identifying that not only the seed, but also the loop, are particularly differentiated regions among human populations. The quantitative computational comparison of signatures of population differentiation showed that candidate microRNAs with the largest differences are enriched in variants implicated in gene expression levels (eQTLs), selective sweeps and pathological processes. We explore the implication of these evolutionary-driven microRNAs and their SNPs in human diseases, such as different types of cancer, and discuss their role in population-specific disease risk.

Epidemiological evidence for associations between variants in microRNA and cancer risk

Numerous papers have reported variants in microRNAs associated with cancer risk; these results, however, are controversial. We seek to offer an updated, comprehensive synopsis of genetic associations between single nucleotide polymorphisms (SNPs) in microRNAs (miRNAs) and cancer risk. We did systematic a field synopsis and meta-analysis to investigate 29 SNPs in 24 miRNAs associated with risk of 18 different kinds of cancer based on data from 247 eligible articles. We graded levels of cumulative epidemiological evidence of significant association using Venice criteria and a false-positive report probability (FPRP) test. We constructed functional annotations for these variants using data from the Encyclopedia of DNA Elements Project. We used FPRP to find additional noteworthy associations between 278 SNPs in 117 miRNAs and risk of 26 cancers based on each SNP with one data source. 16 SNPs were statistically associated with risk of 17 cancers. We graded the cumulative epidemiological evidence as strong for statistical associations between 10 SNPs in eight miRNAs and risk of 11 cancers, moderate for nine SNPs with 12 cancers, and weak for 11 SNPs with 11 cancers. Bioinformatics analysis suggested that the SNPs with strong evidence might fall in putative functional regions. In addition, 38 significant associations were observed in 38 SNPs and risk of 13 cancers. This study offered the a comprehensive research on miRNA gene variants and cancer risk and provided referenced information for the genetic predisposition to cancer risk in future research.

Effect of miR-196a2 rs11614913 Polymorphism on Cancer Susceptibility: Evidence From an Updated Meta-Analysis

Background:MiR-196a2 rs11614913 polymorphism has been studied in a wide range of cancers throughout the years. Despite a large number of epidemiological studies performed in almost all ethnic populations, the contribution of this polymorphism to cancer risk is still inconclusive. Therefore, this updated meta-analysis was performed to estimate a meticulous correlation between miR-196a2 rs11614913 variant and cancer susceptibility. Methods: A systematic study search was carried out using PubMed, ScienceDirect, CNKI, EMBASE, Scopus, and Google Scholar databases following PRISMA guidelines to find necessary literature up to December 15, 2021. Pooled odds ratios with corresponding 95% confidence intervals were estimated using RevMan 5.4 based on ethnicities, cancer types, control sources, and genotyping methods. Results: A total of 152 studies, including 120 135 subjects (53 818 patients and 66 317 controls; 140 studies, after removing studies that deviated from HWE: 51 459 cases and 62 588 controls), were included in this meta-analysis. Quantitative synthesis suggests that the miR-196a2 rs11614913 genetic variant is significantly correlated with the reduced risk of overall cancer in CDM2, CDM3, RM, and AM (odds ratio < 1 and P < .05). It is also observed from ethnicity-based subgroup analysis that rs11614913 polymorphism is significantly (P < .05) linked with cancer in the Asian (in CDM2, CDM3, RM, AM) and the African population (in CDM1, CDM3, ODM). Stratified analysis based on the cancer types demonstrated a significantly decreased correlation for breast, hepatocellular, lung, and gynecological cancer and an increased association for oral and renal cell cancer. Again, the control population-based subgroup analysis reported a strongly reduced correlation for HB population in CDM2, RM, and AM. A substantially decreased risk was also observed for other genotyping methods in multiple genetic models. Conclusions:MiR-196a2 rs11614913 variant is significantly correlated with overall cancer susceptibility. Besides, rs11614913 is correlated with cancer in Asians and Africans. It is also correlated with breast, gynecological, hepatocellular, lung, oral, and renal cell cancer.

Effect of Helicobacter pylori Eradication on Epigenetic Changes in Gastric Cancer-related Genes

It is known that gastric carcinogenesis results from the progressive changes from chronic gastritis to gastric atrophy, intestinal metaplasia, dysplasia, and invasive carcinoma. Several genetic and epigenetic alterations are involved in this process, and Helicobacter pylori (H. pylori) infection is believed to induce the initiation and progression of these steps. From an epigenetic point of view, H. pylori induces hypermethylation of genes involved in the development of gastric cancer and regulates the expression of various microRNAs (miRNAs). These H. pylori-related epigenetic changes are accumulated not only at the site of neoplasm but also in the adjacent non-cancerous gastric mucosa. Thereby, a state vulnerable to gastric cancer known as an epigenetic field defect is formed. H. pylori eradication can have an effective chemopreventive effect in gastric carcinogenesis. However, the molecular biological changes that occur in the stomach environment during H. pylori eradication have not yet been established. Several studies have reported that H. pylori eradication can restore infection-related changes, especially epigenetic alterations in gastric cancer-related genes, but some studies have shown otherwise. Simply put, it appears that the recovery of methylated gastric cancer-related genes and miRNAs during H. pylori eradication may vary among genes and may also differ depending on the histological subtype of the gastric mucosa. In this review, we will discuss the potential mechanism of gastric cancer prevention by H. pylori eradication, mainly from an epigenetic perspective.

Association between rs11614913 Polymorphism of The MiR-196-a2 Gene and Colorectal Cancer in The Presence of Departure from Hardy-Weinberg Equilibrium

Objective

Colorectal cancer (CRC) is the fourth most common and the second most lethal cancer worldwide. CRC mortality is increasing in Iran. In the current study, we aimed to investigate association between rs11614913 polymorphism of the miR-196-a2 gene and CRC.

Materials and Methods

In this case-control study, we assessed association of the rs11614913 polymorphism in 194 patients with CRC (case) and 286 healthy individuals (control). The expectation-maximization (EM) algorithm method was used to adjust deviation from Hardy-Weinberg equilibrium (HWE).

Results

There was no significant difference between genotypic frequencies of rs11614913 polymorphism in the control and case groups. Genotypic frequencies differed in the adjusted and unadjusted deviations from the HWE. Analysis of unadjusted and adjusted independent variables showed that age, sex, alcohol consumption, and drug use were statistically significant.

Conclusion

Our findings showed that rs11614913 polymorphism was not associated with CRC risk. Deviation from HWE affected the results. It is recommended to perform further studies to establish HWE. Ignoring the equilibrium can cause in consistencies in the results of studies.

Characteristics of miRNA-SNPs in healthy Japanese subjects and non-small cell lung cancer, colorectal cancer, and soft tissue sarcoma patients

Single nucleotide polymorphisms in genes encoding microRNAs (miRNA-SNPs) may affect the maturation steps of miRNAs or target mRNA recognition, leading to changes in the expression of target mRNAs to cause gain- or loss-of-function changes. Several miRNA-SNPs are known to be associated with the risk of diseases such as cancer. The purpose of this study was to comprehensively determine the miRNA-SNPs in Japanese individuals to evaluate the differences in allele frequencies between ethnicities by comparing data from the global population in the 1000 Genomes Project and differences between healthy subjects and cancer patients. We performed next-generation sequencing targeting genes encoding 1809 pre-miRNAs. As a result, 403 miRNA-SNPs (146 miRNA-SNPs per subject on average) were identified in 28 healthy Japanese subjects. We observed significant differences in the allele frequencies between ethnicities in 33 of the 403 miRNA-SNPs. The numbers of miRNA-SNPs per subject in 44 non-small cell lung cancer (NSCLC), 33 colorectal cancer (CRC), and 15 soft tissue sarcoma (STS) patients were almost equal to those in healthy subjects. Significant differences in allele frequencies were observed for 14, 11, and 9 miRNA-SNPs in NSCLC, CRC, and STS patients compared with the frequencies in healthy subjects, suggesting that these SNPs can be biomarkers of risk for each type of cancer assessed. In summary, we comprehensively characterized miRNA-SNPs in Japanese individuals and found differences in allele frequencies of several miRNA-SNPs between ethnicities and between healthy subjects and cancer patients. Studies investigating a larger number of subjects should be performed to confirm the potential of miRNA-SNPs as biomarkers of cancer risk.

The Role of microRNAs in Epithelial Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and the major cause of death is mainly attributed to metastasis. MicroRNAs (miRNAs) are a group of small non-coding RNAs that exert important regulatory functions in many biological processes through their effects on regulating gene expression. In most cases, miRNAs interact with the 3′ UTRs of target mRNAs to induce their degradation and suppress their translation. Aberrant expression of miRNAs has been detected in EOC tumors and/or the biological fluids of EOC patients. Such dysregulation occurs as the result of alterations in DNA copy numbers, epigenetic regulation, and miRNA biogenesis. Many studies have demonstrated that miRNAs can promote or suppress events related to EOC metastasis, such as cell migration, invasion, epithelial-to-mesenchymal transition, and interaction with the tumor microenvironment. In this review, we provide a brief overview of miRNA biogenesis and highlight some key events and regulations related to EOC metastasis. We summarize current knowledge on how miRNAs are dysregulated, focusing on those that have been reported to regulate metastasis. Furthermore, we discuss the role of miRNAs in promoting and inhibiting EOC metastasis. Finally, we point out some limitations of current findings and suggest future research directions in the field.

Helicobacter pylori Eradication Can Reverse the Methylation-Associated Regulation of miR-200a/b in Gastric Carcinogenesis

Background/Aims

Epigenetic change is one of the mechanisms that regulates the expression of microRNAs (miRNAs) and is known to play a role in Helicobacter pylori-associated gastric carcinogenesis. We aimed to evaluate the epigenetic changes of miR-200a/b in H. pylori-associated gastric carcinogenesis and restoration after eradication.

Methods

The expression and methylation levels of miR-200a/b were evaluated in gastric cancer (GC) cell lines, human gastric mucosa of H. pylori-negative and -positive controls, and H. pylori-positive GC patients. Next, the changes in the expression and methylation levels of miR-200a/b were compared between H. pylori-eradication and H. pylori-persistence groups at 6 months. Real-time reverse transcription-polymerase chain reaction was conducted to investigate the miRNA expression levels, and MethyLight was performed to assess the methylation levels.

Results

In the GC cell lines, the level of miR-200a/b methylation decreased and the level of expression increased after demethylation. In the human gastric mucosa, the miR-200a/b methylation levels increased in the following group order: H. pylori-negative control group, H. pylori-positive control group, and H. pylori-positive GC group. Conversely, the miR-200a/b expression levels decreased in the same order. In the H. pylori-persistence group, no significant changes were observed in the methylation and expression levels of miR-200a/b after 6 months, whereas the level of methylation decreased and the level of expression of miR-200a/b increased significantly 6 months in the H. pylori-eradication group.

Conclusions

Epigenetic alterations of miR-200a/b may be implicated in H. pylori-induced gastric carcinogenesis. This field defect for cancerization is suggested to be improved by H. pylori eradication.

Predictive role of single nucleotide polymorphism (rs11614913) in the development of breast cancer in Pakistani population

Aim: miRNAs play an important role in breast cancer (BC). Variations in miRNAs influence their maturation, expression and consequently regulation of their target genes. Materials & methods: In this study, single nucleotide polymorphism rs11614913 was genotyped in BC patients (n = 300) and 230 controls by employing tetra primer amplification refractory mutation system PCR and Sanger sequencing (Macrogen Korea). Results: A significant difference was observed in the genotypes through co-dominant (χ².#x00A0;= 42.03; p < 0.0001), additive (odds ratio [OR] = 0.6441 [0.4887-0.8490, 95% confidence interval]; p < 0.0019), dominant (OR = 0.3996 [0.2809-0.5686], p < 0.0001) and recessive (OR = 0.2993 [0.1220-0.7347], p < 0.009) statistical models showed decreased risk association of C allele with BC. Conclusion: Females having CT genotype are at higher risk of BC as compared with those having CC genotype.

rs12416605:C>T in MIR938 associates with gastric cancer through affecting the regulation of the CXCL12 chemokine gene

Background

MicroRNAs are small regulatory RNAs with important roles in carcinogenesis. Genetic variants in these regulatory molecules may contribute to disease. We aim to identify allelic variants in microRNAs as susceptibility factors to gastric cancer using association studies and functional approaches.

Methods

Twenty‐one single nucleotide variants potentially functional, because of their location in either the seed, mature or precursor region of 22 microRNAs, were selected for association studies. Genetic association with gastric cancer in 365 cases and 1,284 matched controls (European Prospective Investigation into Cancer and Nutrition Cohort) was analysed using logistic regression. MicroRNA overexpression, transcriptome analysis, and target gene validation experiments were performed for functional studies.

Results

rs3746444:T>C, in the seed of MIR499A and mature MIR499B, associated with the cardia adenocarcinoma location; rs12416605:C>T, in the seed of MIR938, associated with the diffuse subtype; and rs2114358:T>C, in the precursor MIR1206, associated with the noncardia phenotype. In all cases, the association was inverse, indicating a protective affect against gastric cancer of the three minor allelic variants. MIR499 rs3746444:T>C and MIR1206 rs2114358:T>C are reported to affect the expression of these miRNAs, but the effect of MIR938 rs12416605:C>T is unknown yet. Functional approaches showed that the expression of MIR938 is affected by rs12416605:C>T and revealed that MIR938 could regulate a subset of cancer‐related genes in an allele‐specific fashion. Furthermore, we demonstrated that CXCL12, a chemokine participating in gastric cancer metastasis, is specifically regulated by only one of the rs12416605:C>T alleles.

Conclusion

rs12416605 appears to be involved in gastric cancer by affecting the regulatory function of MIR938 on genes related to this cancer type, particularly on CXCL12 posttranscriptional regulation.

Association of miR-146a, miR-149 and miR-196a2 polymorphisms with neuroblastoma risk in Eastern Chinese population: a three-center case-control study

Neuroblastoma is one of the most common malignancy in childhood, which originates from the developing sympathetic nervous system. Single nucleotide polymorphisms (SNPs) in primary miRNA (pri-miRNA) have shown to associate with cancer susceptibility, including neuroblastoma. Three precursor miRNA (pre-miRNA) SNPs (pre-miR-146a rs2910164, pre-miR-149 rs2292832 and pre-miR-196a2 rs11614913) were found to contribute to pathogenesis of various diseases. Here, to evaluate the association among these three pre-miRNA SNPs and neuroblastoma susceptibility in Eastern Chinese children, we carried out a three-center case-control study involving 312 neuroblastoma cases and 762 healthy controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the association of these three polymorphisms with neuroblastoma risk. However, no significant association was observed among these three SNPs and neuroblastoma susceptibility, in either overall or subgroups analysis by tumor sites, gender and age. Further larger studies consisting of diverse ethnic populations are required to clarify the associations among these three pre-miRNAs polymorphisms and neuroblastoma risk.

Impacts of single nucleotide polymorphisms in three microRNAs (miR-146a, miR-196a2 and miR-499) on the susceptibility to cervical cancer among Indian women

Background: Cervical cancer is the second major female cancer in India and constitutes one-fourth of the world’s burden. Human Papilloma Virus (HPV) infection is an essential but insufficient cause for cervical cancer. Genetic variants in microRNAs (miRNAs/miRs) play an important role in the susceptibility of various types of cancers.

Objective: To evaluate the association of Single Nucleotide Polymorphisms (SNPs) in miR-146a (rs2910164), miR-196a2 (rs11614913), and miR-499 (rs3746444), with cervical cancer susceptibility in Indian population.

Methods: Three hundred samples were genotyped by Polymerase chain reaction (PCR)-Restriction fragment length polymorphism (RFLP). Both patients and controls were also screened for the presence of HPV DNA.

Results: In this case–control study, 125 (83.3%) cervical cancer cases were found to be infected with HPV DNA. The frequency of miR-146a C allele was higher in controls than in cases [odds ratio (OR) (95% confidence interval (CI)) = 0.81 (0.57–1.14), P-value = 0.258]. miR-196a2 T allele was found to be associated with the decreased risk of cervical cancer [OR (95% CI) = 0.36 (0.26–0.50), P-value<0.0001]. Approximately 1.22-fold increased risk has been observed in individuals carrying miR-499 TT genotypes [OR (95% CI) = 1.22 (0.63–2.36), P-value = 0.617]. Interaction studies for miR-196a2/miR-499 loci showed that women carrying TT/CC and TT/CT genotypes were less likely to develop cervical cancer than CC/CC combination [P<0.05]. Likewise, miR-146a/miR-196a2 genotypic combinations (CC/TT, CG/TT, GG/TT) followed the similar trend [P<0.05], exhibited the protective effect against cervical cancer with reference to CC/CC group. Combined genotypes of miR-146a/miR-499 [CC/CT, CG/CC, CG/CT, CG/TT, GG/CC, GG/CT, GG/TT] demonstrated a non-significant trend toward higher cervical cancer risk [OR > 1.00, P>0.05].

Conclusion: Polymorphisms in miR-146a, miR-196a2, and miR-499 individually or collectively have the prospective to emerge as biomarkers for cervical cancer.

Identification of miR-146a and miR-196a-2 single nucleotide polymorphisms at patients with high-grade serous ovarian cancer

MicroRNAs play an essential role in the regulation of gene expression and tumor development. Single nucleotide polymorphism (SNP) can be observed in miRNAs and could influence gene expression. We aimed to identify miR-146a rs2910164 and miR-196a-2 rs11614913 polymorphisms in ovarian cancer patients and controls. 75 patients and 75 controls were involved. DNA was isolated from blood samples. MiR-146a rs2910164 and miR-196a-2 rs11614913 were determined by LightSnip kit. We used melting curve analysis for allele classification. Network analysis was made to find common target genes. We detected 72.67% G allele frequency of miR-146a rs2910164 in controls and 82.00% in patients group (p = 0,053). GG, GC and CC genotypes occurred with 53.33%, 38.67% and 8.00% among controls, with 65.33%, 33.33% and 1.33% among patients, (p = 0.0917). Allele C of miR-196a-2 rs11614913 occurred in 59.33% of controls and in 67.33% of patients (p = 0.15). CC, CT and TT genotypes occurred with 37.33%, 44.00%, and 18.67% frequency in controls, with 46.67%; 41.33% and 12.00% in patients (p = 0.3815). Network analysis found ATG9A, LBR, MBD4 and RUFY2 genes to be targets for both miRNAs. SNPs of miR-146a and miR-196a-2 showed no significant differences between patients and controls. More investigations are required to clarify the exact role of these SNPs in ovarian cancer.

Association of mir-196a-2 rs11614913 and mir-149 rs2292832 Polymorphisms With Risk of Cancer: An Updated Meta-Analysis

Background: Accumulating evidence suggests that functional dysregulations of miRNAs, especially miR-196a-2 and miR-149, in cancers could be attributed to polymorphisms in miRNA sequences. This study was aimed at clarifying the association of mir-196a-2 rs11614913 and mir-149 rs2292832 with cancer risk by performing an updated meta-analysis of genetic association studies. Methods: PubMed, Embase, Scopus, and ScienceDirect databases were searched until 9 April 2018 to identify eligible studies. Studies should meet the following criteria to be included in the meta-analysis: evaluation of genetic association between rs11614913 and/or rs2292832 and susceptibility to cancer; A case-control design; Written in English; Availability of sufficient data for estimating odds ratio (OR) and its 95% confidence interval (95%CI). Studies that met the following criteria were excluded: review articles, meta-analysis, abstracts or conference papers; duplicate publications; studies on animals or cell-lines; studies without a case-control design; studies that did not report genotype frequencies. Pooled ORs and 95% CIs were estimated using a total of 111 studies (41,673 cases and 49,570 controls) for mir-196a rs11614913 and 44 studies (15,954 cases and 19,594 controls) for mir-149 rs2292832. Stratified analysis according to quality scores, genotyping method, ethnicity, broad cancer category and cancer type was also performed. Results: Mir-196a-2 rs11614913 T allele was associated with decreased cancer risk in overall population. The association was only significant in Asians but not Caucasians. In subgroup analysis, significant associations were found in high quality studies, gynecological cancers, ovarian, breast, and hepatocellular cancer. Mir-149 rs2292832 was not associated with cancer risk in overall population and there were no differences between Asians and Caucasians. However, the T allele was associated with a decrease risk of gastrointestinal tract cancers under the heterozygote model and an increased risk of colorectal cancer under the recessive model. Conclusions: The present meta-analysis suggests that mir-196a-2 rs11614913 may contribute to the risk of cancer especially in Asians. Mir-149 rs2292832 may modulate the risk of gastrointestinal tract cancers especially colorectal cancer. This study had some limitations such as significant heterogeneity in most contrasts, limited number of studies enrolling Africans or Caucasians ancestry and lack of adjustment for covariates and environmental interactions.

Variants in the 14q32 miRNA cluster are associated with osteosarcoma risk in the Spanish population

Association studies in osteosarcoma risk found significant results in intergenic regions, suggesting that regions which do not codify for proteins could play an important role. The deregulation of microRNAs (miRNAs) has been already associated with osteosarcoma. Consequently, genetic variants affecting miRNA function could be associated with risk. This study aimed to evaluate the involvement of all genetic variants in pre-miRNAs described so far in relationship to the risk of osteosarcoma. We analyzed a total of 213 genetic variants in 206 pre-miRNAs in two cohorts of osteosarcoma patients (n = 100) and their corresponding controls (n = 256) from Spanish and Slovenian populations, using Goldengate Veracode technology (Illumina). Four polymorphisms in pre-miRNAs at 14q32 miRNA cluster were associated with osteosarcoma risk in the Spanish population (rs12894467, rs61992671, rs58834075 and rs12879262). Pathway enrichment analysis including target genes of these miRNAs pointed out the WNT signaling pathways overrepresented. Moreover, different single nucleotide polymorphism (SNP) effects between the two populations included were observed, suggesting the existence of population differences. In conclusion, 14q32 miRNA cluster seems to be a hotspot for osteosarcoma susceptibility in the Spanish population, but not in the Slovenian, which supports the idea of the existence of population differences in developing this disease.

rs11614913 polymorphism in miRNA-196a2 and cancer risk: an updated meta-analysis

Several epidemiological studies have reported that polymorphisms in microRNA-196a2 (miR-196a2) were associated with various cancers. However, the results remained unverified and were inconsistent in different cancers. Therefore, we carried out an updated meta-analysis to elaborate the effects of rs11614913 polymorphism on cancer susceptibility. A total of 84 articles with 35,802 cases and 41,541 controls were included to evaluate the association between the miR-196a2 rs11614913 and cancer risk by pooled odds ratios (ORs) and 95% confidence intervals (CIs). The results showed that miR-196a2 rs11614913 polymorphism is associated with cancer susceptibility, especially in lung cancer (homozygote comparison, OR =0.840, 95% CI =0.734-0.961; recessive model, OR =0.858, 95% CI =0.771-0.955), hepatocellular carcinoma (allelic contrast, OR =0.894, 95% CI =0.800-0.998; homozygote comparison, OR =0.900, 95% CI =0.813-0.997; recessive model, OR =0.800, 95% CI =0.678-0.944), and head and neck cancer (allelic contrast, OR =1.076, 95% CI =1.006-1.152; homozygote comparison, OR =1.214, 95% CI =1.043-1.413). In addition, significant association was found among Asian populations (allele model, OR =0.847, 95% CI =0.899-0.997, P=0.038; homozygote model, OR =0.878, 95% CI =0.788-0.977, P=0.017; recessive model, OR =0.895, 95% CI =0.824-0.972, P=0.008) but not in Caucasians. The updated meta-analysis confirmed the previous results that miR-196a2 rs11614913 polymorphism may serve as a risk factor for patients with cancers.

Genetic variant of miR-146a rs2910164 C>G and gastric cancer susceptibility

The single nucleotide polymorphism (SNP) rs2910164 G>C within miR-146a has been reported that is associated with the increased risk of gastric cancer (GCa). However, the results are inconclusive, espicially among Asian populations, which probably due to small sample size in each single study. To validate this association and get a more precise estimation, we conducted a large GCa study including 1,125 cases and 1,196 controls in an eastern Chinese population. Our results showed that this SNP was not associated with GCa risk in either of the three genetic models [co-dominant model: CG vs. CC, odds ratio (OR) = 0.99, 95% confidence interval (95%CI): 0.83-1.19; GG vs. CC, OR = 1.03, 95%CI: 0.81-1.32; dominant model: (CG+GG) vs. CC, OR = 1.00, 95%CI = 0.84-1.19; recessive model: GG vs. (CG+CC), OR = 1.04, 95%CI = 0.83-1.29]. Stratified analysis by age, gender, smoking status, drinking status, or tumor location confirmed this non-significant association. In summary, these results suggest that the miR-146a SNP rs2910164 may not be a risk factor for GCa in this Chinese population. Larger and well-designed, preferably prospective studies are needed to further confirm our findings.

Association of Genetic Variants of Small Non-Coding RNAs with Survival in Colorectal Cancer

Background: Single nucleotide polymorphisms (SNPs) of small non-coding RNAs (sncRNAs) can influence sncRNA function and target gene expression to mediate the risk of certain diseases. The aim of the present study was to evaluate the prognostic relevance of sncRNA SNPs for colorectal cancer, which has not been well characterized to date. Methods: We comprehensively examined 31 common SNPs of sncRNAs, and assessed the impact of these variants on survival in a cohort of 188 patients with colorectal cancer. Results: Three SNPs were significantly associated with survival of patients with colorectal cancer after correction for multiple testing, and two of the SNPs (hsa-mir-196a-2 rs11614913 and U85 rs714775) remained significant in multivariate analyses. Additional in silico analysis provided further evidence of this association, since the expression levels of the target genes of the hsa-miR-196a (HOXA7, HOXB8, and AKT1) were significantly correlated with colorectal cancer progression. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that hsa-miR-196a is associated with well-known oncogenic pathways, including cellular protein modification process, mitotic cell cycle, adherens junction, and extracellular matrix receptor interaction pathways. Conclusion: Our results suggest that SNPs of sncRNAs could play a critical role in cancer progression, and that hsa-miR-196a might be a valuable biomarker or therapeutic target for colorectal cancer patients.

Association of miR-196a2 rs11614913 and miR-499 rs3746444 polymorphisms with cancer risk: a meta-analysis

Background

MicroRNAs (miRNAs) are small non-coding RNA molecules, which participate in diverse biological processes and may regulate tumor suppressor genes or oncogenes. Rs11614913 in miR-196a2 and rs3746444 in miR-499 are shown to associate with increased/decreased cancer risk. This meta-analysis was performed to systematically assess the overall association.

Materials and Methods

We searched Pubmed, Web of Knowledge, EMBASE, Chinese National Knowledge Infrastructure (CNKI) databases until December 2016 to identify eligible studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of the associations.

Results

We assessed published studies of the association between these microRNA polymorphisms and cancer risk from 56 studies with 21958/26436 cases/controls for miR-196a2 and from 37 studies with 13759/17946 cases/controls for miR-499. The results demonstrated that miR-196a2 rs11614913 was significantly associated with a decreased cancer risk, in particular with a decreased risk for colorectal cancer and gastric cancer, or for Asian population subgroup. In addition, miR-499 rs3746444 polymorphism was observed as a risk factor for cancers, in particular, for breast cancer, or for in the Asian population.

Conclusions

Our meta-analysis suggests that the rs11614913 most likely contributes to decreased susceptibility to cancer, especially in Asians and colorectal cancer and gastric cancer, and that the rs3746444 may increase risk for cancer. Furthermore, more well-designed studies with large sample size are still necessary to further elucidate the association between polymorphisms and different kinds of cancers risk.

MicroRNA-187 promotes growth and metastasis of gastric cancer by inhibiting FOXA2

MicroRNAs (miRNAs) play an active role in the pathogenesis of gastric cancer. The expression and biological function for miR-187 in gastric cancer remains unknow. In the present study, we demonstrated that miR-187 expression was increased in gastric cancer (GC) tissues and cells. Increased expression level of miR-187 was associated with adverse clinical features including tumor size, lymph metastasis and TNM stage, and decreased overall survival and disease-free survival of GC patients. Functionally, overexpression miR-187 could promote while inhibition of miR-187 could suppress, the proliferation, migration and invasion of GC cells in vitro. In vivo experiments showed that overexpression of miR-187 promoted the growth and lung metastasis of SGC-7901 cells in nude mice. Mechanically, we confirmed that FOXA2 was the downstream target of miR-187 in GC cells using luciferase assay, qRT-PCR and western blot analysis. Moreover, overexpression of FOXA2 abrogated the promoting effects of miR-187 overexpression on SGC-7901 cell proliferation, migration and invasion, while inhibition of FOXA2 reversed the inhibitory effects of miR-187 downregulation on these biological functions of AGS cells, suggesting that FOXA2 was a functional mediator of miR-187 in GC. Therefore, this study indicates that miR-187 is potentially a biomarker and treatment target for GC patients.

Genetic Variation in MicroRNAs and Risk of Oral Squamous Cell Carcinoma in South Indian Population

BACKGROUND

MicroRNAs (miRNAs) are small non-coding RNA molecules, implicated in several activities like initiation, progression and prognosis of various cancers. Single nucleotide polymorphisms (SNPs) in miRNA genes can lead to alteration in mRNA expression, resulting in diverse functional consequences. The aim of our study was to investigate the association of miR-149C>T and miR-196a2C>T SNPs with susceptibility to development of oral squamous cell carcinoma (OSCC) in South Indian subjects.

MATERIALS AND METHODS

100 OSCC patients and 102 healthy controls from the general population were recruited for the study. Genetic analysis was performed by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) as per a standard protocol.

RESULTS

The genotype frequencies in miR-196a2 polymorphism, of TT, CT and CC in the OSCC patients were 69%,10% and 22% respectively while for control group it was 80%, 15% and 5% respectively. The CC genotype of miR196a2 polymorphism was significantly associated with oral squamous cell carcinoma. The genotype frequencies in miR-149 polymorphisms of CC, CT and TT in the oral squamous cell carcinoma (OSCC) patients were 72%, 22% and 6% respectively and for control group 88%, 12% and 0% respectively. CT and TT genotypes of miR149 polymorphism were found to be significantly associated with OSCC (p = 0.05 and 0.07).

CONCLUSIONS

Our study suggests that miR-196a2C>T and miR-149C>T polymorphisms may play crucial roles in the development of OSCC in South Indian subjects.

Role of miRNAs and their potential to be useful as diagnostic and prognostic biomarkers in gastric cancer

Alterations in epigenetic control of gene expression play an important role in many diseases, including gastric cancer. Many studies have identified a large number of upregulated oncogenic miRNAs and downregulated tumour-suppressor miRNAs in this type of cancer. In this review, we provide an overview of the role of miRNAs, pointing to their potential to be useful as diagnostic and/or prognostic biomarkers in gastric cancer. Moreover, we discuss the influence of polymorphisms and epigenetic modifications on miRNA activity.

Circulating microRNA-196a/b are novel biomarkers associated with metastatic gastric cancer

miR-196a and/or miR-196b, involved in cancer initiation and progression, are frequently upregulated in tumour tissues. However, the clinical significance of these microRNAs in gastric cancer (GC) remains to be clarified. In the current study, we investigated the potential utility of circulating miR-196a/b as novel biomarkers for early detection and/or metastatic prognosis of GC. The quantitative real time-polymerase chain reaction data revealed markedly higher pre-operative circulating miR-196a and miR-196b levels in GC patients than healthy controls. Receiver-operating characteristics curve analysis showed that circulating miR-196a, miR-196b and combined miR-196a and miR-196b (miR-196a/b) are more effective than carcinoembryonic antigen or carbohydrate antigen 19-9 alone in distinguishing GC patients from healthy controls, with higher sensitivity and specificity. Circulating miR-196a exhibited higher diagnostic capacity than combined miR-196a/b or miR-196b alone, highlighting its potential as an effective plasma biomarker for GC. In clinicopathological analysis, elevated circulating miR-196a/b levels were highly correlated with metastatic potential or more advanced stages of disease and poorer survival. In addition, the expression levels of circulating miR-196a/b were reduced after surgical resection in GC patients. Taken together, we propose that circulating miR-196a/b serve as a more sensitive and specific novel biomarker than carbohydrate antigen 19-9 for GC monitor, diagnosis and prognosis.

A risk of digestive tract neoplasms susceptibility in miR-146a and miR-196a2

Genome-wide association studies have identified many genes associated with digestive tract neoplasms. However, the published findings have been conflicting. The aim of our study was to evaluate the involvement of two polymorphisms (miR-146a rs2910164, miR-196a2 rs11614913) in digestive tract neoplasms risk and explore how miR-146a and miR-196a2 influence this risk. Systemic research of the PubMed, EBSCO, CBM and VIP databases was performed. The software STATA 12.0 was used to calculate odd ratios and 95% confidence intervals. There were 14 studies (6,053 cases and 6,527 controls) available for rs2910164 and 15 studies (5,648 cases and 6,607 controls) involved in rs11614913. Rs2910164G>C was statistically significantly associated with digestive tract neoplasms (OR 1.134, 95% CI 1.076-1.194, P < 0.001). In the subgroup analysis by ethnicity, significant association was observed in Asian individuals (OR 1.145, 95% CI 1.084-1.209, P < 0.001). We found a correlation between rs11614913 and only colorectal cancer (OR 1.325, 95% CI 1.102-1.594, P = 0.003). This study suggested that digestive tract neoplasms might associate with miR-146a variants, but not miR-196a2 variants.

Common SNP in hsa-miR-196a-2 increases hsa-miR-196a-5p expression and predisposes to idiopathic male infertility in Chinese Han population

MicroRNA plays an important role in spermatogenesis. Whether pre-miRNAs polymorphisms are associated with idiopathic male infertility remains obscure. In this study, 1378 idiopathic infertile males and 486 fertile controls were included between 2006 and 2014. Genotype of three polymorphisms (hsa-mir-146a rs2910164, hsa-mir-196a-2 rs11614913, and hsa-mir-499 rs3746444) and expression of miRNA in seminal plasma were examined by TaqMan method. The role of hsa-miR-196a-5p in cell proliferation, apoptosis and cell cycle were also examined in GC-2 cells. Our results demonstrated that rs11614913 of hsa-miR-196a-2 was significantly associated with idiopathic infertility (TT vs. CT: P = 0.014; TT vs. CC: P = 0.005; TT vs. CT + CC: P = 0.003). In following stratified analysis, we found that rs11614913 exhibited a significantly higher risk of asthenospermia, oligozoospermia and azoospermia. However, no significant association was observed between the other two polymorphisms and idiopathic male infertility risk. In a genotype-expression correlation analysis, rs11614913 CC was significantly associated with elevated expression of hsa-miR-196a-5p (P < 0.05). Additionally, apoptosis levels were significantly increased in hsa-miR-196a-5p mimic treated GC-2 cells, while decreased in hsa-miR-196a-5p inhibitor treated GC-2 cells. Our data revealed a significant relationship between hsa-miR-196a-2 polymorphism and idiopathic male infertility.

Molecular Dynamics: New Frontier in Personalized Medicine

The field of drug discovery has witnessed infinite development over the last decade with the demand for discovery of novel efficient lead compounds. Although the development of novel compounds in this field has seen large failure, a breakthrough in this area might be the establishment of personalized medicine. The trend of personalized medicine has shown stupendous growth being a hot topic after the successful completion of Human Genome Project and 1000 genomes pilot project. Genomic variant such as SNPs play a vital role with respect to inter individual's disease susceptibility and drug response. Hence, identification of such genetic variants has to be performed before administration of a drug. This process requires high-end techniques to understand the complexity of the molecules which might bring an insight to understand the compounds at their molecular level. To sustenance this, field of bioinformatics plays a crucial role in revealing the molecular mechanism of the mutation and thereby designing a drug for an individual in fast and affordable manner. High-end computational methods, such as molecular dynamics (MD) simulation has proved to be a constitutive approach to detecting the minor changes associated with an SNP for better understanding of the structural and functional relationship. The parameters used in molecular dynamic simulation elucidate different properties of a macromolecule, such as protein stability and flexibility. MD along with docking analysis can reveal the synergetic effect of an SNP in protein-ligand interaction and provides a foundation for designing a particular drug molecule for an individual. This compelling application of computational power and the advent of other technologies have paved a promising way toward personalized medicine. In this in-depth review, we tried to highlight the different wings of MD toward personalized medicine.

Association between the rs11614913 variant of miRNA-196a-2 and the risk of epithelial ovarian cancer

Polymorphisms in microRNA (miR) genes and their target sites are a distinct classification of variation in the human genome, which are rapidly being identified and investigated in human cancer. A polymorphism in the miR-196a-2 locus has demonstrated significant associations with various types of cancer, including lung, breast, esophageal and gastric tumors. However, miR-196a-2 has not been fully explored in ovarian cancer, which shares similar biological characteristics with other types of cancer. Therefore, the present study aimed to elucidate the association between a single nucleotide polymorphism (SNP) in the mature sequence of miR-196a-2 (rs11614913, T/C) and the clinical features of 479 Chinese patients with epithelial ovarian cancer (EOC). In addition, the biological significance of this polymorphism was investigated in the OVCAR3 ovarian cancer cell line. Risk association was evaluated in 479 cases of EOC patients and 431 controls. SNPs were analyzed by using polymerase chain reaction based restriction fragment length polymorphism assay. miR-196a expression was evaluated with reverse transcription polymerase chain reaction. The influence of miR-196a-2 rs11614913 T/C on EOC cell migration and invasion ability was further investigated in vitro. The results revealed significant differences in the homozygous CC genotype distribution in patients with EOC (n=479), compared with that of the control subjects (n=431; P=0.026). Analysis of the association between genotype and the risk of EOC revealed that individuals who carried the homozygous CC genotype were 1.34-fold more susceptible to EOC, compared with those carrying the wild-type TT and heterozygous CT genotypes [odds ratio, 1.34; 95% confidence interval, 1.04-2.17; P=0.023]. In addition, the role of this polymorphism in the production of mature miR-196a was investigated. Significantly enhanced production of mature miR-196a was revealed in the C-allelic compared with that of the T-allelic miR-196a-2 precursor (P<0.05). Further examination indicated that miR-196a significantly promoted cell migration and invasion ability in the human OVCAR3 ovarian cell line (P<0.05). In conclusion, the results indicated that the miR-196a-2 rs11614913 CC genotype may increase the risks of ovarian cancer by affecting the expression of mature miR-196a and enhancing cell migration/invasion. The current results provided evidence that the T>C polymorphism in the miR-196a-2 precursor may influence tumorigenesis and metastasis in EOC, and suggested that the functional SNP rs11614913 in the promoter region of pri-miR-196a-2 may be a potential indicator of EOC susceptibility in the population analyzed.

Genetic variants in miR-196a2 and miR-499 are associated with susceptibility to esophageal squamous cell carcinoma in Chinese Han population

Esophageal squamous cell carcinoma (ESCC) is the dominant type of esophageal cancer in the East Asian population. MicroRNAs (miRNAs) have been studied to play important roles in tumorigenesis. Single nucleotide polymorphisms (SNPs) in miRNA lead to the aberrant expression and structural alteration of miRNA and are hypothesized to be involved in tumorigenesis and cancer development. We conducted a population-based case-control study to evaluate the association between SNPs in miRNAs and ESCC risk in 1400 ESCC cases and 2185 matched controls. Four SNPs including miR-196a2 rs11614913, miR-146a rs2910164, miR-499 rs3746444, and miR-423 rs6505162 were selected with comprehensive collection strategy and genotyped using the SNaPshot Multiplex System. Odds ratio (OR) and 95 % confidence interval (95 % CI) were used to assess the strength of association. The CC genotype of miR-196a2 rs11614913 was significantly associated with an increased ESCC risk compared with the TT genotype (OR 1.11, 95 % CI 1.01-1.22, P 0.049) and the TT/TC genotypes (OR 1.09, 95 % CI 1.01-1.19, P 0.043). The association was more pronounced in non-drinkers in the recessive model (OR 1.13, 95 % CI 1.01-1.27, P 0.029). A significantly increased risk of ESCC associated with miR-499 rs3746444 polymorphism was evident among patients who never smoking and drinking. This study suggests that miR-196a2 rs11614913 and miR-499 rs3746444 are associated with an increased ESCC risk in a Chinese population.

Common genetic polymorphisms in pre-microRNAs and risk of bladder cancer

Background

At present, inconsistent association between single nucleotide polymorphism (SNP) in pre-miRNAs (hsa-mir-196a2 rs11614913 C/T, hsa-mir-499 rs3746444 A/G, and hsa-mir-146a rs2910164 C/G) and bladder cancer were obtained in limited studies. We performed a case–control study to test whether these three common polymorphisms are associated with bladder cancer. One hundred fifty-nine patients affected by bladder cancer and 298 unrelated healthy subjects were enrolled in the study.

Methods

Using polymerase chain reaction–restriction fragment length polymorphism assay (PCR–RFLP), genotypes of these three SNPs were determined, and their associations with bladder cancer, as well as with clinic pathological factors, and tumor progression were analyzed.

Results

No association between bladder cancer risk and variant allele of hsa-mir-196a2 rs11614913 C/T, hsa-mir-499 rs3746444 A/G, or hsa-mir-146a rs2910164 C/G was observed. Heterozygous genotype (CT genotype) of rs11614913 was associated with a significantly decreased bladder cancer risk (P = 0.004, OR = 0.56, 95 % CI = 0.38–0.83). Further stratified analyses showed that rs2910164 is associated with the tumor stage in a recessive model and with metastasis in a dominant model (P = 0.012, OR = 0.20, 95 % CI = 0.05–0.72 and P = 0.04, OR = 2.63, 95 % CI = 1.03–6.67, respectively). No association between hsa-mir-499 rs3746444 A/G and bladder cancer was observed.

Conclusions

Our results suggested hsa-mir-196a2 rs11614913 C/T is associated with a significantly decreased risk of bladder cancer and hsa-mir-146a rs2910164 GG genotype is associated with clinical stage and metastasis in bladder cancer.

Effect of a functional polymorphism in the pre-miR-146a gene on the risk and prognosis of renal cell carcinoma

MicroRNAs (miRNAs) are non-coding RNAs that function as regulators of tumor suppressors and oncogenes. A G>C polymorphism (rs2910164) in the miR‑146a precursor sequence leads to a functional change associated with a risk for various types of malignancy. The role of this single nucleotide polymorphism in the pathogenesis of renal cell carcinoma (RCC) has not yet been examined. The present study evaluated the association between rs2910164 genotypes and the risk and prognosis of RCC in a population comprised of 421 RCC cases and 432 controls. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for rs2910164 genotypes according to case status. Cox proportional hazards regression modeling was used to estimate hazards ratios and 95% CIs according to the genotypes among the RCC patients. It was found that the rs2910164 GG and GC genotypes were associated with an increased risk of RCC only in senior subjects (>57‑years old; adjusted OR=1.59, 95% CI=1.04‑2.43). Furthermore, the GC and GG genotypes were associated with a poorer survival rate among patients with RCC compared with the CC genotype (P=0.002). In conclusion, the observed association between the GG and GC genotype and poorer survival rate of RCC was at least partially mediated by the decreased expression of miR-146a.

A Genetic Variant in miRNA-219-1 Is Associated with Risk of Esophageal Squamous Cell Carcinoma in Chinese Kazakhs

Background. Esophageal cancer (EC), an aggressive digestive tract malignancy, is one of the leading causes of cancer-related deaths worldwide. Besides environmental risk factors, genetic factors might play a key role in the EC carcinogenesis. The aim of the study is to evaluate the association of miR219-1 single-nucleotide polymorphisms (SNPs) with EC. Methods. A total of 248 Kazakh esophageal squamous cell carcinoma (ESCC) cases and 300 frequency-matched control subjects were recruited for this study. Genomic DNA was isolated from the samples. The miR-219-1 rs107822G > A and rs213210T > C genotypes were determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Linkage disequilibrium (LD) and haplotype analysis were used to detect the degree of association on miR-219-1 rs107822 and rs213210. Real-time quantitative polymerase chain reaction (qRT-PCR) was performed to detect miR-219-1 expression with miR-219-1 rs107822 polymorphism. Result. The SNP rs107822G > A in the miR-219-1 gene decreased the risk of Kazakh ESCC. Furthermore, two miR-219-1 SNPs, namely, rs107822 and rs213210, may tag each other to decrease the risk of Kazakh ESCC. These findings indicated that functional polymorphisms miR-219-1 rs107822G > A might change individual susceptibility to Kazakh ESCC.

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.

Association of miR-193b down-regulation and miR-196a up-regulation with clinicopathological features and prognosis in gastric cancer

Dysregulated expression of microRNAs (miRNAs) has been shown to be closely associated with tumor development, progression, and carcinogenesis. However, their clinical implications for gastric cancer remain elusive. To investigate the hypothesis that genome-wide alternations of miRNAs differentiate gastric cancer tissues from those matched adjacent non-tumor tissues (ANTTs), miRNA arrays were employed to examine miRNA expression profiles for the 5-pair discovery stage, and the quantitative real-time polymerase chain reaction (qRT- PCR) was applied to validate candidate miRNAs for 48-pair validation stage. Furthermore, the relationship between altered miRNA and clinicopathological features and prognosis of gastric cancer was explored. Among a total of 1,146 miRNAs analyzed, 16 miRNAs were found to be significantly different expressed in tissues from gastric cancer compared to ANTTs (p<0.05). qRT-PCR further confirmed the variation in expression of miR-193b and miR-196a in the validation stage. Down-expression of miR-193b was significantly correlated with Lauren type, differentiation, UICC stage, invasion, and metastasis of gastric cancer (p<0.05), while over-expression of miR-196a was significantly associated with poor differentiation (p=0.022). Moreover, binary logistic regression analysis demonstrated that the UICC stage was a significant risk factor for down-expression of miR-193b (adjusted OR=8.69; 95%CI=1.06-56.91; p=0.043). Additionally, Kaplan-Meier survival curves indicated that patients with a high fold-change of down-regulated miR-193b had a significantly shorter survival time (n=19; median survival=29 months) compared to patients with a low fold-change of down-regulated miR-193b (n=29; median survival=54 months) (p=0.001). Overall survival time of patients with a low fold-change of up-regulated miR- 196a (n=27; median survival=52 months) was significantly longer than that of patients with a high fold-change of up-regulated miR-196a (n=21; median survival=46 months) (p=0.003). Hence, miR-193b and miR-196a may be applied as novel and promising prognostic markers in gastric cancer.

Role of miRNA in cancer diagnosis, prognosis, therapy and regulation of its expression by Epstein-Barr virus and human papillomaviruses: With special reference to oral cancer

MicroRNAs (miRNAs) belong to class of small non-coding RNAs that regulate numerous biological processes by targeting broad set of messenger RNAs. Research on miRNA-based biomarkers has witnessed phenomenal growth, owing to non-invasive nature of miRNA based screening assays and their sensitivity and specificity in detecting cancers. Their discovery in humans in 2000 has led to an explosion in research in terms of their role as biomarker, therapeutic target and trying to elucidate their function. This review aims to summarize the function of microRNAs as well as to examine how dysregulation at any step in their biogenesis or functional pathway can play a role in development of cancer, together with its possible involvement in oral cancer. Overexpression of oncogenic miRNA may reduce protein products of tumor-suppressor genes but loss of tumor-suppressor miRNA expression may cause elevated levels of oncogenic protein. One or both of these alterations could represent new targets for cancer diagnosis and treatment in future. Many researchers have focused on genetic and epigenetic alterations in OSCC cells. The genetic susceptibility, endemic environment factors, and Epstein-Barr virus (EBV) infection are believed to be the major etiologic factors of OSCC. Once metastasis occurs, prognosis is very poor. It is urgently needed to develop biomarkers for early clinical diagnosis/prognosis, and novel effective therapies for oral carcinoma. High-risk HPV infection leads to aberrant expression of cellular oncogenic and tumor suppressive miRNAs. The emergence of miRNA knowledge, and its potential interactive action with such alterations, therefore creates new understanding of cell transformation.

Effects of Two Common Polymorphisms rs2910164 in miR-146a and rs11614913 in miR-196a2 on Gastric Cancer Susceptibility

Background. Single nucleotide polymorphisms (SNPs) in genes encoding microRNAs may play important role in the development of gastric cancer. It has been reported that common SNPs rs2910164 in miR-146a and rs11614913 in miR-196a2 are associated with susceptibility to gastric cancer. The published results remain inconclusive or even controversial. A meta-analysis was conducted to quantitatively assess potential association between the two common SNPs and gastric cancer risk. Methods. A comprehensive literature search was performed in multiple internet-based electronic databases. Data from 12 eligible studies were extracted to estimate pooled odds ratios (ORs) and 95% confidence intervals (95% CI). Results. C allele of rs2910164 is associated with reduced gastric cancer risk in heterozygote model and dominant model whereas rs11614913 indicates no significant association. Subgroup analysis demonstrates that C allele of rs2910164 and rs11614913 may decrease susceptibility to diffuse type gastric cancer in dominant model and recessive model, respectively, while rs11614913 increased intestinal type gastric cancer in dominant model. Conclusion. SNPs rs2910164 and rs11614913 might have effect on gastric cancer risk in certain genetic models and specific types of cancer. Further well-designed studies should be considered to validate the potential effect.

Genetic variants in miRNA processing genes and pre-miRNAs are associated with the risk of chronic lymphocytic leukemia

Genome wide association studies (GWAS) have identified several low-penetrance susceptibility alleles in chronic lymphocytic leukemia (CLL). Nevertheless, these studies scarcely study regions that are implicated in non-coding molecules such as microRNAs (miRNAs). Abnormalities in miRNAs, as altered expression patterns and mutations, have been described in CLL, suggesting their implication in the development of the disease. Genetic variations in miRNAs can affect levels of miRNA expression if present in pre-miRNAs and in miRNA biogenesis genes or alter miRNA function if present in both target mRNA and miRNA sequences. Therefore, the present study aimed to evaluate whether polymorphisms in pre-miRNAs, and/or miRNA processing genes contribute to predisposition for CLL. A total of 91 SNPs in 107 CLL patients and 350 cancer-free controls were successfully analyzed using TaqMan Open Array technology. We found nine statistically significant associations with CLL risk after FDR correction, seven in miRNA processing genes (rs3805500 and rs6877842 in DROSHA, rs1057035 in DICER1, rs17676986 in SND1, rs9611280 in TNRC6B, rs784567 in TRBP and rs11866002 in CNOT1) and two in pre-miRNAs (rs11614913 in miR196a2 and rs2114358 in miR1206). These findings suggest that polymorphisms in genes involved in miRNAs biogenesis pathway as well as in pre-miRNAs contribute to the risk of CLL. Large-scale studies are needed to validate the current findings.

Association between single nucleotide polymorphisms in miRNA196a-2 and miRNA146a and susceptibility to hepatocellular carcinoma in a Chinese population

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers in the world and deeply threatens people's health, especially in China. Techniques of early diagnosis, prevention and prediction are still being discovered, among which the approaches based on single nucleotide polymorphisms in microRNA genes (miRNA SNPs) are newly proposed and show prospective potential. In particular, the association between SNPs in miRNA196a-2 (rs11614913) and miRNA146a (rs2910164) and HCC has been investigated. However, the conclusions made were conflicting, possibly due to insufficient sample size or population stratification. Further confirmations in well-designed large samples are still required. In this study, we verified the association between these two SNPs and the susceptibility to HCC by MassARRAY assay in a 2,000 large Chinese case-control sample. Significant association between rs11614913 and HCC was confirmed. Subjects with the genotype of CT+TT or T allele in rs11614913 were more resistant to HCC (CT+TT: OR (95% CI)=0.73 (0.57-0.92), P=0.01; T allele: OR (95% CI)=0.85 (0.75-0.97), P=0.02) and HBV-related HCC (CT+TT: OR (95% CI)=0.69 (0.53-0.90), P=0.01; T allele: OR (95% CI)=0.82 (0.71-0.95), P=0.01). The affected carriers of CT or TT also tended to have lower levels of serum AFP (P=0.01). This study demonstrated a role of rs11614913 in the etiology of HCC. Further research should focus on the clinical use of this miRNA SNP, so as to facilitate conquering HCC.