A new polymorphism biomarker rs629367 associated with increased risk and poor survival of gastric cancer in chinese by up-regulated miRNA-let-7a expression

Pyrones Isolated from Annona Acutiflora Exhibit Promising Cytotoxic Effects on Cancer Cell Lines

This work discusses the ongoing challenge of cancer, focusing on therapy issues such as chemotherapy resistance and adverse drug effects. It emphasizes the need for new anticancer agents with improved efficacy and fewer side effects, exploring natural products from plant sources. The Annonaceae family, specifically the Annona genus, is highlighted for its medicinal properties, including anti-inflammatory and anticancer effects. The study focuses on the isolation and elucidation of the substances present in Annona acutiflora leaves. The methodology involves chromatographic and spectroscopy techniques. The isolated compounds, (6S)-5'-oxohepten-1'E,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (1), (6R)-5'-oxohepten-1'Z,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (2) and (6R)-5'-oxohepten-1'Z,3'E-dienyl)-5,6-dihydro-2H-pyran-2-one (3) were investigated for cytotoxicity assays on cancer cell lines and normal cells. Results show promising cytotoxic activity, particularly with compound 3, demonstrating potential activity against oral cancer (43.18 μM), hepatocarcinoma (17.24 μM), melanoma (5.39 μM), and colon cancer (59.03 μM). The compound outperforms carboplatin in selectivity against oral cancer (S. I. 2.15) and melanoma (S. I. 17.22). The study concludes by suggesting the potential of these α-pyrones as effective and less toxic alternatives for cancer therapy.

Oncogenes and tumor suppressor genes: functions and roles in cancers

Cancer, being the most formidable ailment, has had a profound impact on the human health. The disease is primarily associated with genetic mutations that impact oncogenes and tumor suppressor genes (TSGs). Recently, growing evidence have shown that X-linked TSGs have specific role in cancer progression and metastasis as well. Interestingly, our genome harbors around substantial portion of genes that function as tumor suppressors, and the X chromosome alone harbors a considerable number of TSGs. The scenario becomes even more compelling as X-linked TSGs are adaptive to key epigenetic processes such as X chromosome inactivation. Therefore, delineating the new paradigm related to X-linked TSGs, for instance, their crosstalk with autosome and involvement in cancer initiation, progression, and metastasis becomes utmost importance. Considering this, herein, we present a comprehensive discussion of X-linked TSG dysregulation in various cancers as a consequence of genetic variations and epigenetic alterations. In addition, the dynamic role of X-linked TSGs in sex chromosome-autosome crosstalk in cancer genome remodeling is being explored thoroughly. Besides, the functional roles of ncRNAs, role of X-linked TSG in immunomodulation and in gender-based cancer disparities has also been highlighted. Overall, the focal idea of the present article is to recapitulate the findings on X-linked TSG regulation in the cancer landscape and to redefine their role toward improving cancer treatment strategies.

Impact of pri-let-7a-1 rs10739971 for Gastric Cancer Predisposition in an Amazon Region

Gastric cancer (GC) is the fifth most common type of cancer and the fourth leading cause of cancer death. In Brazil, GC has a high incidence and mortality rates, and it is highly variable by region. The Amazon region has significant rising rates among all Brazil regions. Only very few studies have evaluated the association between genetic variants and the risk of gastric cancer in the Brazilian Amazon population. Therefore, this study aimed to investigate associations between single nucleotide polymorphisms of miRNA processing genes and the risk for GC in this population. Potentially functional single nucleotide polymorphisms from miRNA processing genes were genotyped in 159 cases and 193 healthy controls by QuantStudio Real Time PCR. According to our findings, the genotype GG of the variant rs10739971 presents a lower risk to the development of GC in comparison to the remaining genotypes (p = 0.000016; OR = 0.055; 95% CI = 0.015-0.206). This is the first study to report the association of pri-let-7a-1 rs10739971 with GC in the Brazilian Amazon population, which is a highly mixed population with a unique genetic constitution that is different from other populations that are studied in the vast majority of scientific research.

Association between SNPs in microRNAs and microRNAs-Machinery Genes with Susceptibility of Leprosy in the Amazon Population

Leprosy is a chronic neurodermatological disease caused by the bacillus Mycobacterium leprae. Recent studies show that SNPs in genes related to miRNAs have been associated with several diseases in different populations. This study aimed to evaluate the association of twenty-five SNPs in genes encoding miRNAs related to biological processes and immune response with susceptibility to leprosy and its polar forms paucibacillary and multibacillary in the Brazilian Amazon. A total of 114 leprosy patients and 71 household contacts were included in this study. Genotyping was performed using TaqMan Open Array Genotyping. Ancestry-informative markers were used to estimate individual proportions of case and control groups. The SNP rs2505901 (pre-miR938) was associated with protection against the development of paucibacillary leprosy, while the SNPs rs639174 (DROSHA), rs636832 (AGO1), and rs4143815 (miR570) were associated with protection against the development of multibacillary leprosy. In contrast, the SNPs rs10739971 (pri-let-7a1), rs12904 (miR200C), and rs2168518 (miR4513) are associated with the development of the paucibacillary leprosy. The rs10739971 (pri-let-7a1) polymorphism was associated with the development of leprosy, while rs2910164 (miR146A) and rs10035440 (DROSHA) was significantly associated with an increased risk of developing multibacillary leprosy.

Family History and Risk of Upper Gastrointestinal Cancer in the Linxian General Population

OBJECTIVE

The objective of this study was to investigate family history (FH) of upper gastrointestinal (UGI) cancer and risk of esophageal squamous cell carcinoma (ESCC), gastric cardia carcinoma (GCC), and gastric non-cardia carcinoma (GNCC) in the Linxian General Population Nutrition Intervention Trial (NIT) cohort. Methods: This prospective analysis was conducted using the Linxian NIT cohort data. Subjects with FH of UGI cancer was treated as an exposed group while the remainders were considered as a comparison group. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between FH of UGI cancer and risk of UGI cancer incidence and mortality were estimated using Cox proportional hazards models.

RESULTS

There were 5,680 newly diagnosed UGI cancer cases during the follow-up period, with a total of 4,573 UGI cancer deaths occurred, including 2,603 ESCC, 1,410 GCC, and 560 GNCC deaths. A positive FH of UGI cancer was associated with a significantly increased risk of ESCC and GCC (Incidence: HRESCC = 1.45, 95%CI: 1.35-1.56; HRGCC = 1.27, 95%CI: 1.15-1.40; Mortality: HRESCC = 1.40, 95%CI: 1.30-1.52; HRGCC = 1.27, 95%CI: 1.14-1.42) after adjusting for age at baseline, gender, smoking status, alcohol drinking, education level, and frequency of fresh fruit and vegetable consumption. Subjects with FH in both parents had the highest risk of ESCC and GCC incidence (HRESCC = 1.65, 95%CI: 1.40-1.95; HRGCC = 1.42, 95%CI: 1.12-1.81) and deaths (HRESCC = 1.65, 95%CI: 1.38-1.97; HRGCC = 1.42, 95%CI: 1.09-1.85). Spouse diagnosed with UGI cancer did not increase the risk of any UGI cancers of the subjects. In subgroup analysis, FH of UGI cancer was shown to significantly increase the risk of GCC in non-drinkers (Incidence: HR = 1.31, 95%CI: 1.17-1.47; Mortality: HR = 1.33, 95%CI: 1.17-1.50). No associations were observed for risk of GNCC. Sensitivity analysis by excluding subjects who were followed up less than three years did not materially alter our results.

CONCLUSION

Our data point to the role of the FH of UGI cancer to the risk of ESCC and GCC incidence and mortality. The influence of family history on the risk of UGI cancer varies from different types of family members.

Identification of miRNAs as diagnostic and prognostic markers in hepatocellular carcinoma

The development of high-throughput technologies has yielded a large amount of data from molecular and epigenetic analysis that could be useful for identifying novel biomarkers of cancers. We analyzed Gene Expression Omnibus (GEO) DataSet micro–ribonucleic acid (miRNA) profiling datasets to identify miRNAs that could have value as diagnostic and prognostic biomarkers in hepatocellular carcinoma (HCC). We adopted several computing methods to identify the functional roles of these miRNAs. Ultimately, via integrated analysis of three GEO DataSets, three differential miRNAs were identified as valuable markers in HCC. Combining the results of receiver operating characteristic (ROC) analyses and Kaplan–Meier Plotter (KM) survival analyses, we identified hsa-let-7e as a novel potential biomarker for HCC diagnosis and prognosis. Then, we found via quantitative reverse-transcription polymerase chain reaction (RT-qPCR) that let-7e was upregulated in HCC tissues and that such upregulation was significantly associated with poor prognosis in HCC. The results of functional analysis indicated that upregulated let-7e promoted tumor cell growth and proliferation. Additionally, via mechanistic analysis, we found that let-7e could regulate mitochondrial apoptosis and autophagy to adjust and control cancer cell proliferation. Therefore, the integrated results of our bioinformatics analyses of both clinical and experimental data showed that let-7e was a novel biomarker for HCC diagnosis and prognosis and might be a new treatment target.

Polymorphisms in Pepsinogen C and miRNA Genes Associate with High Serum Pepsinogen II in Gastric Cancer Patients

Background: Pepsinogen (PG) II (PGII) is a serological marker used to estimate the risk of gastric cancer but how PGII expression is regulated is largely unknown. It has been suggested that PGII expression, from the PGC (Progastricsin) gene, is regulated by microRNAs (miRNA), but how PGII levels vary with Helicobacter pylori (H. pylori) infection and miRNAs genotype remains unclear. Methods: Serum levels of PGI and PGII were determined in 80 patients with gastric cancer and persons at risk for gastric cancer (74 first-degree relatives of patients, 62 patients with autoimmune chronic atrophic gastritis, and 2 patients with dysplasia), with and without H. pylori infection. As control from the general population, 52 blood donors were added to the analyses. Associations between PGII levels and genetic variants in PGC and miRNA genes in these groups were explored based on H. pylori seropositivity and the risk for gastric cancer. The two-dimensional difference in gel electrophoresis (2D-DIGE) and the NanoString analysis of messenger RNA (mRNAs) from gastric cancer tissue were used to determine the pathways associated with increased PGII levels. Results: PGII levels were significantly higher in patients with gastric cancer, and in those with H. pylori infection, than in other patients or controls. A PGI/PGII ratio ≤ 3 was found better than PGI < 25 ng/mL to identify patients with gastric cancer (15.0% vs. 8.8%). For two genetic variants, namely rs8111742 in miR-Let-7e and rs121224 in miR-365b, there were significant differences in PGII levels between genotype groups among patients with gastric cancer (p = 0.02 and p = 0.01, respectively), but not among other study subjects. Moreover, a strict relation between rs9471643 C-allele with H. pylori infection and gastric cancer was underlined. Fold change in gene expression of mRNA isolated from gastric cancer tissue correlated well with polymorphism, H. pylori infection, increased PGII level, and pathway for bacteria cell entry into the host. Conclusions: Serum PGII levels depend in part on an interaction between H. pylori and host miRNA genotypes, which may interfere with the cut-off of PGI/PGII ratio used to identify persons at risk of gastric cancer. Results reported new findings regarding the relation among H. pylori, PGII-related host polymorphism, and genes involved in this interaction in the gastric cancer setting.

Genetic polymorphisms in pri-let-7a-2 are associated with ischemic stroke risk in a Chinese Han population from Liaoning, China: a case-control study

Ischemic stroke is a complicated disease, and its pathogenesis has been attributed to the occurrence of genetic polymorphisms. Evidence has suggested that the microRNA let-7a is involved in the pathogenesis of ischemic stroke. Pri-miRNA is the primary transcript, which undergoes several processing steps to generate pre-miRNA and, later, mature miRNAs. In this case-control study, we analyzed the distribution of pri-let-7a-2 variants in patients at a high risk for ischemic stroke and the interactions of pri-let-7a-2 variants and environmental factors. Blood samples and clinical information were collected from 1086 patients with ischemic stroke and 836 healthy controls between December 2013 and December 2015 at the First Affiliated Hospital of China Medical University. We found that the rs1143770 CC genotype and the C allele were associated with a decreased risk of ischemic stroke, whereas the rs629367 CC genotype was associated with an increased risk for ischemic stroke. Moreover, these two single-nucleotide polymorphisms were in linkage disequilibrium in this study sample. We analyzed gene-environment interactions and found that rs1143770 exerted a combined effect on the pathogenesis of ischemic stroke, together with alcohol use, smoking, and a history of hypertension. Therefore, the detection of pri-let-7a-2 polymorphisms may increase the awareness of ischemic stroke risk. This study was approved by the Institutional Ethics Committee of the First Affiliated Hospital of China Medical University, China (approval No. 2012-38-1) on February 20, 2012, and was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR-COC-17013559) on December 27, 2017.

Association of the mir-499 polymorphisms with oral cavity and oropharyngeal squamous cell carcinoma in an Iranian population

BACKGROUND

Oral squamous cell carcinoma (SCC) is the most common oral malignancy. Some evidence indicated that there is a correlation between microRNA single nucleotide polymorphisms and the risk of oral cancer. The aim of the current study was to investigate the association between mir-499 polymorphism with the risk of oral cavity and oropharyngeal SCC in a subset of Iranian Population.

MATERIALS AND METHODS

In this case-control pilot study total of 112 participants including 56 histopathlogically confirmed oral and oropharyngeal SCC patients and 56 age- and sex-matched controls were included The mir-499 rs3746444 T/C polymorphism was detected using polymerase chain reaction-restriction fragment length polymorphism method. The comparisons of the distribution of the allele and genotype frequencies were performed using Chi-square test, and P < 0.05 was considered as statistically significant.

RESULTS

The result of the present study indicated that the frequency distribution of mir-499 was not significantly different between cases and controls (P > 0.05). We also did not find any significant association between the risk of the cancer and mir-499 polymorphisms in the recessive (Odds ratio [OR]: 6.60; 95% confidence interval [CI]: 0.77-56.74; P = 0.11) and dominant (OR: 1; 95% CI: 0.37-2.74; P = 1) inheritance models even after adjustment for smoking.

CONCLUSION

The results of the present study indicated that the polymorphisms of mir-499 are not associated with the risk of oral and oropharyngeal SCC in Iranian population. However, further large scale studies are needed to validate our findings.

Effects of microRNAs polymorphism in cancer progression

MicroRNAs (miRNAs) are known as a new class of small RNAs (18-25 nucleotides) that regulate gene expression at multiple levels from transcription to translation. Considering the important role of miRNAs in cell proliferation, differentiation, and apoptosis, any variations in their expression can contribute to various anomalies, such as tumorigenesis. Single-nucleotide polymorphisms (SNPs) have received much attention as potential genetic markers for diseases due to their advantage of being present at a high frequency in the human genome. SNPs can occur in different parts of the miRNA genes (primary, precursor, and mature) which result in pathological conditions. In this study, recent findings related to the effects of SNPs in miRNAs on their biogenesis and functions and their role in cancer development and progression are discussed. This review was performed using PubMed to search for related reports. The identified effects may be useful for clinical decision-making and providing important new information about the pathophysiology of miRNAs.

Circulating exosomal miRNAs: clinical significance in human cancers

Introduction: The identification of novel noninvasive biomarkers to ameliorate early-diagnosis, and disease prognosis, as well as to support personalized treatment and monitoring decisions is of first clinical priority for cancer patients' care. Exosomes are natural endosome-derived extracellular vesicles that have emerged as crucial mediators of intercellular communication and tumor progression. Considering that deregulated miRNA levels have been described in numerous human malignancies and that tumor-derived exosomes reflect miRNA expression of donor tumor cells, the evaluation of exosome-derived circulating miRNAs (exomiRs) may offer a new promising class of noninvasive molecular markers to improve patients' management and quality-of-life. Areas covered: In the current review we have summarized the existing knowledge on the clinical relevance of circulating exosomal miRNAs in improving cancer diagnosis and prognosis, and thus supporting personalized patients' management Expert commentary: Cancer research has highlighted the abundance of exomiRs in patients' plasma and serum samples, as well as their biomarker capabilities in the vast majority of human malignancies studied so far. Their analytical stability constitutes exomiRs ideal molecular markers to overcome numerous limitations of cancer clinical management, while future large-scale studies should unveil exomiRs translational utility in modern cancer molecular diagnostics.

A functional variant in the flanking region of pri-let-7f contributes to colorectal cancer risk in a Chinese population

Let-7f was reported to be downregulated in patients with colorectal cancer (CRC). However, little is known about the role of let-7f in CRC carcinogenesis. The aim of this study was to investigate the correlation between genetic polymorphisms in the flanking region of pri-let-7f and CRC risk, as well as the potential role of let-7f in CRC cell migration and invasion. The pri-let-7f-1 rs10739971 and pri-let-7f-2 rs17276588 were genotyped using TaqMan (Applied Biosystems, Foster City, CA) assay. The luciferase activity was detected using Dual-Luciferase Reporter Assay. CRC cell migration and invasion were evaluated using transwell chamber assay. The rs17276588 AG and AG/AA genotypes had a significantly increased CRC risk (AG vs. GG: adjusted odds ratio [OR] = 1.48, 95% confidence interval [CI] = 1.19-1.83, p < 0.001; AG/AA vs. GG: adjusted OR = 1.43, 95% CI = 1.17-1.75, p < 0.001). Stratification analyses showed that the increased risk was observed in CRC patients with well-moderately differential status, patients with clinical Stages I-II, and patients without lymph node metastasis. The rs17276588A allele displayed a decreased transcriptional activity and low levels of let-7f. Moreover, let-7f inhibited migration and invasion in Caco-2 and Lovo cells. These findings indicate that the rs17276588 AG/AA genotypes increased CRC risk by reducing the expression of tumor suppressor let-7f.

Polymorphisms in miRNA genes play roles in the initiation and development of cervical cancer

MicroRNA deregulation is crucial for cancer development. Studies showed that polymorphisms in miRNA genes could affect miRNA expression, which might be associated with cancer development. In the current study, we investigated the association of seven single nucleotide polymorphisms (SNPs) in seven miRNA genes with the initiation and development of cervical cancer in a Chinese Han population. The SNPs of 358 cervical intraepithelial neoplasia (CIN) patients, 547 cervical cancer patients and 567 healthy individuals were genotyped using TaqMan assays. Moreover, we evaluated the association of the seven SNPs with the different stages of cervical cancer. Our results showed that rs4636297 in miR-126 was associated with susceptibility to CIN and cervical cancer (P=0.019 and 0.019, respectively) and that the T allele was associated with a higher risk of CIN (OR=1.334, 95% CI: 1.049-1.698) and cervical cancer (OR=1.296, 95% CI: 1.044-1.609). Similarly, rs11614913 in miR-125a was associated with CIN and cervical cancer (P=0.025 and 0.015, respectively), and the T allele might be the protective factor for CIN (OR=0.807, 95% CI: 0.669-0.974) and cervical cancer (OR=0.814, 95% CI: 0.689-0.961). Our results indicated that rs4636297 in miR-126 and rs11614913 in miR-196a2 play an important role only in the initiation of cervical cancer not in the development of CIN to cervical cancer.

Genetic associations between the miRNA polymorphisms miR-130b (rs373001), miR-200b (rs7549819), and miR-495 (rs2281611) and colorectal cancer susceptibility

BACKGROUND

Recent studies have extensively investigated the role of miRNAs in colorectal cancer (CRC), and several associations have been reported. In addition, single nucleotide polymorphisms (SNPs) in promoter regions of miRNAs have been shown to affect miRNA expression. Therefore, we aimed to analyze the effect of miRNA polymorphisms on CRC susceptibility.

METHODS

We conducted association studies on the relationships between the miRNA polymorphisms miR-130bT > C rs373001, miR-200bT > C rs7549819, and miR-495A > C rs2281611 and CRC with 472 CRC patients and 399 control subjects in Korea.

RESULTS

Multivariate logistic regressions of the CRC subgroups showed that the miR-495CC genotype associated with rectal cancer (AA+AC vs. CC; adjusted odds ratio (AOR) for CC, 1.592; 95% confidence interval (CI), 1.071-2.368; P = 0.022). The gene-environment combinatorial analysis showed that the combination of miR-495A > C and low plasma folate contributed to an increased risk of rectal cancer (AA+AC vs. CC; AOR for CC, 3.829; 95% CI, 1.577-9.300; P = 0.003). In the survival analysis, miR-200bT > C associated with CRC patient mortality (TT vs TC + CC; adjusted hazard ratio for TC + CC, 0.592; 95% CI, 0.373-0.940; P = 0.026).

CONCLUSION

In this study, we found that miR-200b and miR-495 polymorphisms are involved in CRC susceptibility and prognosis.

Genetic polymorphisms of miRNA let7a-2 and pri-mir-34b/c are associated with an increased risk of papillary thyroid carcinoma and clinical/pathological features

microRNAs (miRNAs) as a group of short noncoding RNAs are crucial molecules in transcriptional and translational regulation of oncogenes and tumor suppressor genes. Evidence showed there was an association between the miRNA polymorphisms and various cancers, including papillary thyroid carcinoma (PTC). The present study aims to evaluate the possible effects of let7a-2 rs1143770 and pri-mir-34b/c rs4938723 polymorphisms on PTC susceptibility. A total of 120 patients with PTC and 130 age, sex, and race matched controls were enrolled in the case-control study. The polymerase chain reaction-restriction fragment length polymorphism method was used for genotyping of let7a-2 rs1143770 and pri-mir-34b/c rs4938723 polymorphisms. The let7a-2 rs1143770 CT and TT genotypes were associated with a 1.9-fold and 2.2-fold higher risk of PTC, respectively (P = 0.027 and P = 0.041). Moreover, the let7a-2 rs1143770 polymorphism was associated with increased PTC risk in both dominant (2-fold, P = 0.015) and the allelic model (1.5-fold, P = 0.03). The frequency of pri-mir-34b/c rs4938723TC genotype was significantly higher in patients with PTC and associated with a two-fold higher risk of PTC (P = 0.013). In addition, this polymorphism was associated with a 1.8-fold increased risk of PTC in dominant model (P = 0.021). The let7a-2 rs1143770CT genotype was associated with a 3.5-fold increased risk of N1 stage in PTC patients (P = 0.04), however, pri-mir-34b/c rs4938723TC genotype was associated with a 3.4-fold and 5.1-fold increased risk of III-IV stage and vascular invasion in PTC group, respectively (P = 0.04 and P = 0.04). In conclusion, the present study shows that let7a-2 rs1143770 and pri-mir-34b/c rs4938723 polymorphisms could be susceptible factors for PTC and some clinical features.

Lethal-7-related polymorphisms are associated with susceptibility to and prognosis of gastric cancer

BACKGROUND

The lethal-7 (let-7) family members and their targets are involved in the development and progression of tumors. Let-7-related polymorphisms have been reported to be associated with tumorigenesis and prognosis. In gastric cancer, however, the related studies are limited.

AIM

To investigate the role of let-7-related microRNA polymorphisms in the tumorigenesis and prognosis of gastric cancer in a Chinese population.

METHODS

A total of 898 gastric cancer patients and 992 tumor-free controls were recruited into this study from 2008 to 2013. Gastric cancer patients were followed periodically. Ten single nucleotide polymorphisms (SNPs) in the let-7 gene region or their target mRNAs were genotyped using the MassARRAY system and their associations with the risk for or overall survival of gastric cancer were analyzed.

RESULTS

All the ten SNPs were in Hardy-Weinberg equilibrium. The C allele of the rs3811463 polymorphism in the 3’-untranslated region (UTR) of LIN28A was associated with a lower risk of gastric cancer [odds ratio (OR) = 0.74, 95% confidence interval (CI): 0.61-0.88, P = 0.001] after adjustment for age and Helicobacter pylori status. Seven hundred and thirty-five gastric cancer patients who had undergone radical tumorectomy were included in the survival analysis and their 5-year survival rate was 53.9% (95%CI: 50.1%-57.6%). The rs10889677 in the 3’-UTR of IL23R was corresponded to the prognosis of gastric cancer in a dose-response manner, in which the death risk increased by 25% [hazard ratio (HR) = 1.25, 95%CI: 1.04-1.45, P = 0.011] with each increase in the number of C alleles after controlling for other potential clinicopathological parameters.

CONCLUSION

The let-7-related polymorphism rs3811463 in LIN28A is associated with the susceptibility to gastric cancer and the let-7-related polymorphism rs10889677 in IL23R is associated with the prognosis of gastric cancer.

MiRNA Polymorphisms and Cancer Prognosis: A Systematic Review and Meta-Analysis

Background: Accumulating studies have focused on the relationship between miRNAs polymorphisms and cancer prognosis. However, the results are conflicting and unconvincing. This systematic review and meta-analysis was conducted to explore the relationship between miRNAs polymorphisms and cancer prognosis, aiming to seek for markers with cancer prognostic function.

Methods: Hazard ratio of overall survival, disease-free survival (DFS) and recurrence-free survival were calculated to evaluate the association between miRNAs polymorphisms and cancer prognosis by using Stata software 11.0.

Results: We systematically reviewed the association of 17 miRNAs SNPs with cancer prognosis including 24,721 samples. It was shown that 6 miRNAs SNPs (miR-608 rs4919510, miR-492 rs2289030, miR-378 rs1076064, miR-499 rs4919510, miR-149 rs2292832, miR-196a2 rs11614913) were associated with better cancer overall survival (OS) while let-7i rs10877887 was associated with poor OS; the homozygous and heterozygote genotype of miR-423 were related to poor cancer relapse-free survival (RFS) when compared with the wild genotype; miR-146 rs2910164 was linked to favorable cancer DFS while miR-196a2 rs11614913 was associated with poor DFS.

Conclusions: In summary, let-7i rs10877887, miR-608 rs4919510, miR-492 rs2289030, miR-378 rs1076064, miR-423 rs6505162, miR-499 rs4919510, miR-149 rs2292832, miR-146 rs2910164, and miR-196a2 rs11614913 might serve as potential biomarkers for cancer prognosis.

Correlations of MicroRNA-21 Gene Polymorphisms With Chemosensitivity and Prognosis of Cervical Cancer

BACKGROUND

We investigated correlations of miR-21 gene polymorphisms including rs1292037 (A > G) and rs13137 (A > T) with the chemosensitivity to cisplatin plus paclitaxel, and prognosis before cervical cancer (CC) surgery, which may provide a novel target for prevention and treatment of CC.

MATERIALS AND METHODS

A total of 165 patients with CC were divided into 2 groups, a sensitive group and resistance group. Gene polymorphisms of rs1292037 (A > G) and rs13137 (A > T) were detected respectively. Logistic and Cox multivariate regression analyses were used to explore factors that influence resistance to cisplatin plus paclitaxel.

RESULTS

rs1292037 (A > G) locus AG, GG, AG + GG and G allele in miR-21 gene may increase chemoresistance to cisplatin plus paclitaxel in CC. The risk factors of prognosis included rs1292037 (A > G) locus, tumor stage, maximum lesion diameter and lymph node metastasis (hazard ratio [HR] = 1.819, 95% CI = 1.127-2.935; HR = 1.504, 95% CI = 1.070-2.114; HR = 1.671, 95% CI = 1.038-2.689; HR = 3.043, 95% CI = 1.783-5.193). The influencing factors of resistance to cisplatin plus paclitaxel included maximum lesion diameter, tumor stage, lymph node metastasis and rs1292037 (odds ratio [OR] = 14.047, 95% CI = 5.694-34.653; OR = 5.873, 95% CI = 3.104-11.110; OR = 3.574, 95% CI = 1.554-8.216; OR = 2.449, 95% CI = 1.052-5.705).

CONCLUSIONS

rs1292037 (A > G) locus are associated with the chemoresistance to cisplatin plus paclitaxel and prognosis of patients with CC. In addition to that, the G allele at rs1292037 (A > G) locus increases the risk of preoperative chemoresistance to cisplatin plus paclitaxel and is a poor prognostic factor for patients with CC.

A comprehensive evaluation for polymorphisms in let-7 family in cancer risk and prognosis: a system review and meta-analysis

miRNA polymorphisms had potential to be biomarkers for cancer susceptibility and prognosis. The mature miRNA-let-7 family was considered as the most important miRNA for the cancer incidence and progression. Recently, the promising let-7 miRNAs were reported to be associated with various cancers, but the results were inconsistent. We performed a first-reported systematic review with a meta-analysis for the association of let-7 family single nucleotide polymorphisms (SNPs) with cancer risk/prognosis. Ten studies were included with a total of 3878 cancer cases and 4725 controls for the risk study and 1665 cancer patients for the prognosis study in this meta-analysis. In the risk study, the let-7i rs10877887 and let-7a-1/let-7f-1/let-7d rs13293512 were shown no significant association for the overall cancer risk. In the stratified analysis, the rs10877887 variant genotype was significantly associated with a decreased cancer risk in head and neck cancer (TC compared with TT: P=0.017; odds ratio (OR) = 0.81; TC + CC compared with TT: P=0.020; OR = 0.82). In the prognosis study, the let-7i rs10877887 SNP was shown to be associated with a higher risk for cancer prognosis in the dominate model (P=0.004; hazard ratio (HR) = 1.32). The other two SNPs (let-7a-1 rs10739971 and let-7a-2 rs629367) were not found to be associated with cancer survival. None of the let-7 family polymorphisms had potential to be biomarkers for cancer susceptibility but let-7i rs10877887 SNP had potential to be predicting markers for cancer prognosis. In the future, large-sample studies are still needed to verify our findings.

Levels of MicroRNA Heterogeneity in Cancer Biology

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression, involved in the silencing of messenger RNA (mRNA) translation. The importance of miRNA signatures in disease screening, prognosis, and progression of different tumor types and subtypes is increasing. miRNA expression levels change depending on numerous factors. In this review, we are describing the circumstances under which miRNA levels can change, these are named 'levels' of heterogeneity of miRNAs. miRNAs can have oncogenic, tumor suppressive, or both roles depending on tumor type and target mRNA whose translation they silence. The expression levels of a single miRNA may vary across different cancer types and subtypes, indicating that a miRNA signature may be tissue specific. miRNA levels of expression also vary during disease formation and propagation, indicating the presence of a time profile for their expression. The complexity of the miRNA-mRNA interference network mirrors different genetic and epigenetic changes that influence miRNA and mRNA availability to each other, and hence, their binding ability. The potential role of miRNAs as biomarkers is two-fold; first, for monitoring of the phases of cancer pathogenesis, and second, to characterize the particular type/subtype of cancer. It is important that a particular miRNA should be characterized by examining as many types and subtypes of cancers as are available, as well as being extracted from different types of samples, in order to obtain a complete picture of its behavior and importance in the disease pathology.

miRNA-146a rs2910164 C>G polymorphism increased the risk of esophagogastric junction adenocarcinoma: a case-control study involving 2,740 participants

Purpose

The miRNA-146a rs2910164 C>G polymorphism may contribute to the development of cancer. However, the association between this polymorphism and the risk of esophagogastric junction adenocarcinoma (EGJA) remains unclear. In the present study, we carried out a case–control study to explore the potential relationship between miRNA-146a rs2910164 C>G polymorphism and EGJA risk.

Patients and methods

In total, 1,063 EGJA patients and 1,677 cancer-free controls were enrolled. The SNPscan^™ genotyping assay, a patented technology, was used to test the genotyping of miRNA-146a rs2910164 C>G polymorphism.

Results

We found that miRNA-146a rs2910164 C>G polymorphism was associated with a risk of developing EGJA (additive model: adjusted odds ratio (OR), 1.27; 95% CI, 1.07–1.51; P=0.006; homozygote model: adjusted OR, 1.31; 95% CI, 1.03–1.65; P=0.027 and dominant model: adjusted OR, 1.36; 95% CI, 1.15–1.60; P<0.001). After adjustment for the Bonferroni correction, these associations were also found in additive and dominant genetic models. In the subgroup analyses, after adjustment by sex, age, alcohol consumption, and smoking status, results of multiple logistic regression analysis indicated that miRNA-146a rs2910164 C>G polymorphism increased the risk of EGJA in males, females, <64 years old, ≥64 years old, never smoking, and never drinking subgroups.

Conclusion

The current study highlights that the miRNA-146a rs2910164 C>G polymorphism increased the risk of EGJA in eastern Chinese Han population.

Functional miRNA variants affect lung cancer susceptibility and platinum-based chemotherapy response

Background

Platinum-based chemotherapy is widely used as the first-line treatment of lung cancer. MicroRNAs have an important role in lung carcinogenesis and progression. Single-nucleotide polymorphisms (SNPs) in miRNA involved in miRNA biogenesis and structural alteration may affect miRNA expression. In this study, we aimed to investigate the association of functional miRNA variants with the lung cancer susceptibility and platinum-based chemotherapy response.

Methods

Nine genetic polymorphisms in miR-605, 146a, 149, 196a-2, 27a, 499, 30c-1, 5197 and let-7a-2 were selected with comprehensive collection strategy and genotyped by MALDI-TOF mass spectrometry in a total of 215 health control and 507 lung cancer patients (386 patients received at least two consecutive cycles of platinum-based chemotherapy).

Results

We found that an allele carriers of miR-146a rs2910164 (P=0.022, OR=1.315) and C allele carriers of miR-149 rs71428439 (P=0.042, OR=1.372) performance a high risk of lung cancer. Mir-30c-1 rs928508 (P=0.005, in recessive model) and let-7a-2 rs629367 (P=0.030 and P=0.021, in additive and dominant models, respectively) showed strong relationship with lung cancer risk in age under 57 years. The rs11614913 (miR-196a-2) C allele or rs9280508 (miR-30c-1) G allele carriers shown more sensitive to platinum both in additive (P=0.010, P=0.022, respectively) and dominant models (P=0.001, P=0.018, respectively).

Conclusions

These findings suggested that SNPs rs71428439 (miR-149), rs2910164 (miR-146a), rs928508 (mir-30c-1) and rs629367 (let-7a-2) were associated with the lung cancer prevalence, polymorphisms of rs11614913 (miR-196a-2) and rs9280508 (miR-30c-1) significantly influenced the patients' response to platinum-based chemotherapy, which may serve as potential clinical biomarkers to predict lung cancer risk and platinum-based chemotherapy response.

Correlations of pri-Let-7 gene polymorphisms with the recurrence and metastasis of primary liver cancer after transcatheter arterial chemoembolization

BACKGROUND AND AIM

Single nucleotide polymorphisms (SNPs) within miRNAs could change their production or affinity with target genes, thus leading to malignant diseases. This study aims to explore correlations of pri-let-7 gene polymorphisms with the recurrence and metastasis of primary liver cancer (PLC) after a transcatheter arterial chemoembolization (TACE) surgical procedure.

MATERIALS AND METHODS

A total of 302 PLC patients treated with hepatoprotective therapies after TACE were selected to and assigned into recurrent and non-recurrent groups. Genotypes of pri-let-7a-1 rs1073997 and pri-let-7a-2 rs629367 were analyzed by Taqman assay. The relationship between PLC with the mutation of each SNP was determined by a multivariate logistic regression analyses. Moreover, the association between survival and pri-let-7 gene polymorphisms was analyzed by the Kaplan-Meier method. The Progress Free Survival (PFS) curve, correlation of pri-let-7a-1 rs629367 with alcohol, HBsAg-positive and TNM III/IV were analyzed by a stratified analysis. Additionally, the risk factors for the recurrence of PLC were analyzed by a multivariate logistic regression analyses.

RESULTS

Results showed that the allelic frequency of the pri-let-7a-2 rs629367 SNP in the recurrent group was higher than that of the non-recurrent group. The distribution of CC genotype was significantly higher than non-CC genotype in the recurrent group. Alcohol consumption, positive expression of hepatitis B surface antigen (HBsAg), AC + CC genotype of rs629367 and TNM III/IV were determined to be the risk factors for the recurrence and metastasis of PLC after TACE. We found a positive correlation between pri-let-7a-2 rs629367 with alcohol consumption, HBsAg-positive and TNM III/IV. The median PFS of HBsAg-positive and TNM III/IV patients with the AC + CC genotype of rs629367 was shorter than those with non-AC + CC genotype.

CONCLUSION

Our findings provide evidence that patients with PLC that carry the AC + CC genotype of pri-let-7a-2 rs629367 after TACE have a worse prognosis than those who carry the AA genotype. We speculate that the pri-let-7 rs629367 SNP could be used as a predictor of recurrence and metastasis after TACE for patients with PLC.

SNP-SNP interactions of three new pri-miRNAs with the target gene PGC and multidimensional analysis of H. pylori in the gastric cancer/atrophic gastritis risk in a Chinese population

Gastric cancer (GC) is a multistep complex disease involving multiple genes, and gene–gene interactions have a greater effect than a single gene in determining cancer susceptibility. This study aimed to explore the interaction of the let-7e rs8111742, miR-365b rs121224, and miR-4795 rs1002765 single nucleotide polymorphisms (SNPs) with SNPs of the predicted target gene PGC and Helicobacter pylori status in GC and atrophic gastritis (AG) risk. Three miRNA SNPs and seven PGC SNPs were detected in 2448 cases using the Sequenom MassArray platform. Two pairwise combinations of miRNA and PGC SNPs were associated with increased AG risk (let-7e rs8111742 – PGC rs6458238 and miR-4795 rs1002765 – PGC rs9471643). Singly, miR-365b rs121224 and PGC rs6912200 had no effect individually but in combination they demonstrated an epistatic interaction associated with AG risk. Similarly, let-7e rs8111742 and miR-4795 rs1002765 SNPs interacted with H. pylori infection to increase GC risk (rs8111742: P_interaction = 0.024; rs1002765: P_interaction = 0.031, respectively). A three-dimensional interaction analysis found miR-4795 rs1002765, PGC rs9471643, and H. pylori infection positively interacted to increase AG risk (P_{interaction =} 0.027). Also, let-7e rs8111742, PGC rs6458238, and H. pylori infection positively interacted to increase GC risk (P_{interaction =} 0.036). Furthermore, both of these three-dimensional interactions had a dosage–effect correspondence (P_trend < 0.001) and were verified by MDR. In conclusion, the miRNAs SNPs (let-7e rs8111742 and miR-4795 rs1002765) might have more superior efficiency when combined with PGC SNPs and/or H. pylori for GC or AG risk than a single SNP on its own.

Single nucleotide polymorphisms and cancer susceptibility

A large number of genes associated with various cancer types contain single nucleotide polymorphisms (SNPs). SNPs are located in gene promoters, exons, introns as well as 5'- and 3'- untranslated regions (UTRs) and affect gene expression by different mechanisms. These mechanisms depend on the role of the genetic elements in which the individual SNPs are located. Moreover, alterations in epigenetic regulation due to gene polymorphisms add to the complexity underlying cancer susceptibility related to SNPs. In this systematic review, we discuss the various genetic and epigenetic mechanisms involved in determining cancer susceptibility related to various SNPs located in different genetic elements. We also discuss the diagnostic potential of these SNPs and the focus for future studies.

A global burden of gastric cancer: the major impact of China

Gastric cancer (GC) is a highly aggressive cancer and a major cause of cancer-related deaths worldwide. Approximately half of the world's GC cases and deaths occur in china. GC presents challenges in early diagnosis and effective therapy due to a lack of understanding of the underlying molecular biology. The primary goals of this review are to outline current GC research in china and describe future trends in this field. Areas covered: This review mainly focuses on a series of GC-related advances China has achieved. Considerable progress has been made in understanding the role of H. pylori in GC by a series of population-based studies in well-established high-risk areas; A few germline and somatic alterations have been identified by 'omics' studies; Studies on the mechanisms of malignant phenotypes have helped us to form an in-depth understanding of GC and advance drug discovery. Moreover, identification of potential biomarkers and targeted therapies have facilitated the diagnosis and treatment of GC. However, many challenges remain. Expert commentary: To combat GC, sufficient funding is important. More attention should be paid on early diagnosis and the discovery of novel efficient biomarkers and the development of biomarker-based or targeted therapeutics in GC.

MiR-27a rs895819 is involved in increased atrophic gastritis risk, improved gastric cancer prognosis and negative interaction with Helicobacter pylori

MiR-27a rs895819 is a loop-stem structure single nucleotide polymorphism affecting mature miR-27a function. In this study, we performed a comprehensive analysis about the association of rs895819 with gastric cancer risk and prognosis, atrophic gastritis risk, as well as the interactions with environmental factors. A total of 939 gastric cancer patients, 1,067 atrophic gastritis patients and 1,166 healthy controls were screened by direct sequencing and MALDI-TOF-MS. The association of rs895819 with clinical pathological parameters and prognostic survival in 357 gastric cancer patients was also been analyzed. The rs895819 variant genotype increased the risk for atrophic gastritis (1.58-fold) and gastric cancer (1.24-fold). While in stratified analysis, the risk effect was demonstrated more significantly in the female, age >60y, Helicobacter pylori (H. pylori) negative and non-drinker subgroups. Rs895819 and H. pylori showed an interaction effect for atrophic gastritis risk. In the survival analysis, the rs895819 AG heterozygosis was associated with better survival than the AA wild-type in the TNM stage I–II subgroup. In vitro study by overexpressing miR-27a, cells carrying polymorphic-type G allele expressed lower miR-27a than wild-type A allele. In conclusion, miR-27a rs895819 is implicated as a biomarker for gastric cancer and atrophic gastritis risk, and interacts with H. pylori in gastric carcinogenesis.

Association of Polymorphisms in three pri-miRNAs that Target Pepsinogen C with the Risk and Prognosis of Gastric Cancer

We aimed to explore the associations of polymorphisms in three microRNAs (miRNAs) (let-7e rs8111742, miR-365b rs121224 and miR-4795 rs1002765) that target PGC with the risk and prognosis of gastric cancer/atrophic gastritis. Sequenom’s MassArray was used to genotype the miRNA polymorphisms in 724 gastric cancer cases, 862 atrophic gastritis cases and 862 controls in a Chinese population. We found that let-7e rs8111742 and miR-4795 rs1002765 were associated with the risk of gastric cancer in the H. pylori-positive subgroup. MiR-365b rs121224 was associated with the risk of intestinal-type gastric cancer in the alcohol consumption subgroup. Intestinal-type gastric cancer patients at Borrmann stages III-IV who carry the miR-365b rs121224 GG genotype had better prognosis compared with those who carry the CG or CC genotypes. MiR-365b rs121224 was associated with Lauren typing and TNM staging, in which the distribution of GG genotype carriers in intestinal-type gastric cancer and the TNM stage I-II subgroup was higher than that of CG or CC genotypes, which contrasted with the distribution in diffuse-type gastric cancer or TNM III-IV groups. These findings suggested that the polymorphisms in these miRNAs might be biomarkers for gastric cancer risk and prognosis, especially for populations infected with Helicobacter pylori or who consume alcohol.

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.

Pri-let-7a-1 rs10739971 polymorphism is associated with gastric cancer prognosis and might affect mature let-7a expression

The relationship between the pri-let-7a-1 rs10739971 polymorphism and gastric cancer (GC) risk has been reported. However, the role of this polymorphism in the prognosis of GC remains largely elusive. Sequenom MassARRAY platform method and the polymerase chain reaction (PCR)-restriction fragment length polymorphism were used to investigate pri-let-7a-1 rs10739971 G→A in 334 GC patients. Real-time PCR detected expression of mature let-7a in serum and tissue. Patients with AA or GA+AA genotypes of the pri-let-7a-1 rs10739971 polymorphism demonstrated significantly longer survival time than those with the wild GG genotype. Stratified analysis indicated that survival time was significantly longer in women with AA or GA+AA genotypes and in Borrmann type I/II patients with GA heterozygote or GA+AA genotypes. AA genotype was more frequent in the lymphatic-metastasis-negative subgroup. Serum mature let-7a expression in healthy people with the GA heterozygote and the GA+AA genotype was higher than in those with the GG genotype, and the difference remained significant in the female healthy subgroup. Pri-let-7a-1 rs10739971 polymorphism might be a biomarker for GC prognosis, especially for female and Borrmann type I/II patients. The pri-let-7a-1 rs10739971 polymorphism might affect serum mature let-7a expression, and partly explain the mechanism of the relationship between the pri-let-7a-1 rs10739971 polymorphism and GC survival.

MicroRNAs May Serve as Emerging Molecular Biomarkers for Diagnosis and Prognostic Assessment or as Targets for Therapy in Gastric Cancer

Gastric cancer (GC) is one of the most common cancers, with high incidences in East Asia countries. Most GC patients have been reported with low early diagnosis rate and show extremely poor prognosis. Therefore, it is necessary to develop novel and more sensitive biomarkers to improve early diagnosis and therapy in order to provide longer survival and better quality of life for gastric cancer patients. MicroRNAs (miRNAs) play crucial roles in GC development and progression. miRNAs have emerged as a novel molecular biomarker for cancer diagnosis, prognosis and therapy with surprising stability in tissues, serum or other body fluids. This review summarizes major advances in our current knowledge about potential miRNA biomarkers for GC that have been reported in the past two years.

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.

Dysregulation of non-coding RNAs in gastric cancer

Gastric cancer (GC) is one of the most common cancers in the world and a significant threat to the health of patients, especially those from China and Japan. The prognosis for patients with late stage GC receiving the standard of care treatment, including surgery, chemotherapy and radiotherapy, remains poor. Developing novel treatment strategies, identifying new molecules for targeted therapy, and devising screening techniques to detect this cancer in its early stages are needed for GC patients. The discovery of non-coding RNAs (ncRNAs), primarily microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), helped to elucidate the mechanisms of tumorigenesis, diagnosis and treatment of GC. Recently, significant research has been conducted on non-coding RNAs and how the regulatory dysfunction of these RNAs impacts the tumorigenesis of GC. In this study, we review papers published in the last five years concerning the dysregulation of non-coding RNAs, especially miRNAs and lncRNAs, in GC. We summarize instances of aberrant expression of the ncRNAs in GC and their effect on survival-related events, including cell cycle regulation, AKT signaling, apoptosis and drug resistance. Additionally, we evaluate how ncRNA dysregulation affects the metastatic process, including the epithelial-mesenchymal transition, stem cells, transcription factor activity, and oncogene and tumor suppressor expression. Lastly, we determine how ncRNAs affect angiogenesis in the microenvironment of GC. We further discuss the use of ncRNAs as potential biomarkers for use in clinical screening, early diagnosis and prognosis of GC. At present, no ideal ncRNAs have been identified as targets for the treatment of GC.

c-Myc Represses Tumor-Suppressive microRNAs, let-7a, miR-16 and miR-29b, and Induces Cyclin D2-Mediated Cell Proliferation in Ewing's Sarcoma Cell Line

Myc oncogenic transcription factor is known to inhibit tumor suppressive microRNAs (miRNAs), resulting in greater expression of their target protein related to cell cycle, invasion or anti-apoptotic factors in human cancer cells. To explore possible oncogenic factors in Ewing’s sarcoma (ES), we conducted microarray-based approach to profile the changes in the expression of miRNAs and its downstream mRNAs in five ES cell lines and human mesenchymal stem cells (hMSCs). Three miRNAs, let-7a, miR-16 and miR-29b were significantly down-regulated, whereas c-Myc and cyclin D2 (CCND2) were significantly up-regulated in all tested ES cells compared with hMSCs. To verify that let-7a, miR-16 and miR-29b were the targets of c-Myc in ES cell lines, we transfected siRNA against c-Myc and confirmed the coordinate up-regulation of let-7a, miR-16 and miR-29b through the repression of c-Myc. The ES cells transfected with c-Myc-siRNA and let-7a, miR-16 and miR-29b exhibited the inhibition of the cell cycle progression. The increased expression of let-7a, miR-16 and miR-29b resulted in the reduction of CCND2 protein expression. We also demonstrated that c-Myc-siRNA treatment of ES cells was associated with the decreased expression of CCND2 as a down-stream of three miRNAs. Furthermore, the introduction of let-7a, miR-16 and miR-29b in ES cells could inhibit the c-Myc-mediated up-regulation of CCND2 resulted in the prevention of cell cycle progression. In addition, the transfection of let-7a, miR-16 and miR-29b in ES cells suppressed tumor growth ex vivo treatment. These findings suggests that the up-regulation of c-Myc inhibited the expression of let-7a, miR-16 and miR-29b subsequently induced CCND2 expression in ES cells. The present study might identify a novel oncogenic axis that c-Myc regulates the expression of CCND2 via let-7a, miR-16 and miR-29b, leading to the development new therapeutic targets for ES.

Genetic variants in the promoters of let-7 family are associated with an increased risk of major depressive disorder

BACKGROUND

Let-7 family plays a critical role in the pathogenesis of major depressive disorder (MDD). Genetic polymorphisms in the promoters of miRNA may influence individual׳s susceptibility to diseases. The purpose of this study was to investigate the association between rs10877887 and rs13293512 polymorphisms in the promoters of let-7 family and the risk of MDD.

METHOD

Polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing assays were used to analyze the rs10877887 and rs13293512 polymorphisms in 237 MDD patients and 296 controls.

RESULTS

We found that the rs10877887 CC genotype was associated with an increased risk of MDD (CC vs. TT: OR=1.73, 95% CI, 1.04-2.86, P=0.03, and CC vs.

TT/TC

OR=1.74, 95% CI, 1.08-2.80, P=0.02, respectively). Similarly increased risk was also observed for the rs13293512 (CC vs. TT: OR=1.83, 95% CI, 1.12-2.99, P=0.015; CC vs.

TT/TC

OR=1.84, 95% CI, 1.20-2.81, P=0.005; and C vs. T: OR=1.32, 95% CI, 1.03-1.68, P=0.03, respectively). Stratification analysis showed that patients with the rs13293512 TC and CC genotypes had a 2.29 and 2.56-fold increased risk of MDD recurrence after treatment (TC vs. TT: 95% CI, 1.23-4.25, P=0.008; CC vs. TT: 95% CI, 1.25-5.23, P=0.009, respectively).

LIMITATIONS

Relatively small sample size and hospital-based study design may influence the results.

CONCLUSIONS

Our findings suggest that the rs10877887 and rs13293512 polymorphisms may be related to the development of MDD.

Genetic variation in miR-100 rs1834306 is associated with decreased risk for esophageal squamous cell carcinoma in Kazakh patients in northwest China

MicroRNAs (miRNAs) are a family of small noncoding RNAs that act as oncogenes and tumor suppressors. Single nucleotide polymorphisms (SNPs) in miRNAs may be associated with changes in phenotype and function. The aim of this study was to verify whether genetic variations in candidate microRNA (miRNA or miR) genes could contribute to esophageal squamous cell carcinoma (ESCC) susceptibility. A case-control study in 248 Kazakh patients with ESCC and 300 frequency matched control subjects was carried out to examine the potential association of six miRNA (miR-100 rs1834306, miR-34b/c rs4938723, miR-375 rs6715345, miR-146a rs2910164, miR-423 rs6505162 and miR-373 rs12983273) polymorphisms with risk of ESCC. We found that miR-100 rs1834306 T>C polymorphism was associated with a significant decreased risk of ESCC. In the recessive model, when the miR-100 rs1834306 TT/TC genotypes were used as the reference group, the CC homozygote genotype was associated with a significant decreased risk for ESCC (adjusted OR=0.495, 95% CI: 0.349-0.702, P=8.05×10(-5)). In the dominant model, when the miR-100 rs1834306 TT genotypes was used as the reference group, the TC/CC genotype were associated with a borderline statistically decreased risk for ESCC (adjusted OR=0.665, 95% CI: 0.430-1.031, P=0.067). In addition, the miR-100 rs1834306 C allele in the Kazakh population was significantly associated with decreased risk of ESCC (OR=0.609, 95% CI: 0.48-0.78, P=8.37×10(-5)). These findings indicated that functional polymorphism miR-100 rs1834306 C>T might contribute to decreased ESCC risk.

Evaluation of miRNA-binding-site SNPs of MRE11A, NBS1, RAD51 and RAD52 involved in HRR pathway genes and risk of breast cancer in China

MiRNA-binding-site single nucleotide polymorphisms (SNPs) in homologous recombination repair (HRR) pathway genes may change DNA repair capacity and affect susceptibility to cancer though complex gene-gene and gene-reproductive factors interactions. However, these SNPs associated with breast cancer (BC) are still unclear in Chinese women. Therefore, we conducted a case-control study to evaluate the genetic susceptibility of the five miRNA-binding-site SNPs in HRR pathway genes (MRE11A rs2155209, NBS1 rs2735383, RAD51 rs963917 and rs963918 and RAD52 rs7963551) in the development of BC. MRE11A rs2155209 and RAD52 rs7963551 were found to be associated with BC risk (ORadjusted: 1.87; 95 % CI: 1.23-2.86 and ORadjusted: 0.36; 95 % CI: 0.24-0.58). NBS1 rs2735383, RAD51 rs963917 and rs963918 were associated with BC risk after stratification according to reproductive factors. Haplotypes of Crs963917Ars963918 decreased the risk of BC (ORadjusted: 0.53; 95 % CI: 0.4-0.68), while the Trs963917Ars963918 and Trs963917Grs963918 haplotypes could increase the risk of BC (ORadjusted: 1.28; 95 % CI: 1.05-1.57 and ORadjusted: 1.31; 95 % CI: 1.09-1.62). Combined effect of risk alleles showed that the five SNPs were associated with increased BC risk in a dose-dependent manner (P trend = 0.003). The GC genotype of rs2735383, AG + GG genotype of rs963918 and AC + CC genotype of rs7963551 were associated with PR positivity of BC patients. These findings suggest that the miRNA-binding-site SNPs involved in HRR pathway genes may affect susceptibility of BC in Chinese women; moreover, the interactions of gene-gene and gene-reproductive factors play vital roles in the progression of BC. Further functional studies with larger sample are needed to support and validate these findings.

Genetic Variations and Gastric Cancer

<b><i>Background:</i></b> Gastric cancer (GC) has an apparent hereditary component. However, in a large fraction of gastric cases, no known genetic syndrome or family history can be identified, suggesting the presence of ‘missing heritability' in GC etiology. Genome-wide association studies (GWAS) and traditional candidate gene studies have both led to the identification of multiple replicable common genetic variants associated with GC risk. <b><i>Summary:</i></b> We summarize the genetic variants associated with GC risk identified up to date. Achievements derived from translational cancer research including the following aspects: (a) contribution to the our understanding of gastric tumorigenesis, (b) guidance to individualized treatment and (c) prediction of patient prognosis. We also prospect future research direction such as post-GWAS analyses and rare variants studies. <b><i>Key Message:</i></b> Many genetic variants were found through GWAS or candidate gene studies, and interpreting their underlying mechanisms will help us translate risk profiles generated from these variations into use in the clinical setting for targeted screening and treatment. <b><i>Practical Implications:</i></b> Investigation of the potential use of genetic variations as prognostic and predictive markers is a developing field. Many people could benefit from a better understanding of genetic polymorphisms to potentially identify a priori individuals who might have the best chance of survival and therefore derive most clinical benefit from treatment. Outcomes of particular scientific interest for molecular epidemiologic studies should include overall survival, recurrence- and progression-free survival, response to treatment, and early and late toxicities stemming from chemotherapy and radiation.

Let-7 related genetic variation and risk of metabolic syndrome in a Chinese population

MicroRNA (miRNA) related genetic variation may change miRNA binding affinity and mRNA expression levels of the target genes, thus leading to altered metabolic parameters. This study explored the influence of let-7 related single nucleotide polymorphisms (SNPs) on individual susceptibility to metabolic syndrome (MetS) in a Chinese population. Seven SNPs located at the pri-let-7 gene region, pre-let-7 gene region or 3'-UTR of the KRAS gene were selected. The SNPs were genotyped in 503 MetS patients and 529 normal controls using the high-throughput Sequenom genotyping platform. Unconditional logistic regression analysis was utilized to estimate the association between these SNPs and the risk of MetS. There are three SNPs significantly associated with MetS. The A allele of rs17276588 was associated with an increased risk effect for MetS (Adjusted OR=1.75, 95%CI 1.37-2.25, P<0.001). Rs10993081 AG genotype was significantly associated with an increased risk of MetS compared with AA genotypes (Adjusted OR=1.42, 95%CI 1.11-1.83, P=0.006). Rs10877887 TC genotype was significantly associated with an increased risk of MetS compared with TT genotypes (Adjusted OR=1.52, 95% CI 1.16-1.99, P=0.002). Additionally, interactions between rs7045890 and rs712, rs17276588 and rs10877887 were significantly associated with risk of MetS. In conclusion, our study found that let-7 related genetic variation is associated with MetS and may contribute to the susceptibility of MetS. Larger, prospective studies are warranted to validate our findings.

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

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