Research IndicatorsGraph generated 31 August 2019 using data from PubMed using criteria.
Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic. Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex
Specific Cancers (8)
Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.
Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).
Numbers shown below represent number of publications held in OncomiRDB database for Oncogenic and Tumor-Suppressive MicroRNAs.
|Tissue||Target Gene(s)||Regulator(s)||MIR124-1 Function in Cancer||Effect|
|CDK6 (1)||inhibit cell migration (1)|
inhibit cell invasion (1)
decrease cell growth (1)
-acute lymphoblastic leukemia (1)
|CDK6 (1)||DNA hypermethylation (1)|
histone modification (1)
|reduce tumorigenicity (1)||tumor-suppressive
Source: OncomiRDB Wang D. et al. Bioinformatics 2014, 30(15):2237-2238.
miRBase, University of Manchester
Annotated database entry including the location and sequence of the mature miRNA sequence.
miRCancer, East Carolina University
Search miRCancer for miR-124a associations with cancer and associated genes.
OMIM, Johns Hopkin University
Referenced article focusing on the relationship between phenotype and genotype.
International Cancer Genome Consortium.
Summary of gene and mutations by cancer type from ICGC
COSMIC, Sanger Institute
Somatic mutation information and related details
GEO Profiles, NCBI
Search the gene expression profiles from curated DataSets in the Gene Expression Omnibus (GEO) repository.
Latest Publications: MIR124-1 (cancer-related)
Hwang DW, Choi Y, Kim D, et al.Graphene oxide-quenching-based fluorescence in situ hybridization (G-FISH) to detect RNA in tissue: Simple and fast tissue RNA diagnostics.
Nanomedicine. 2019; 16:162-172 [PubMed
] Related Publications
FISH-based RNA detection in paraffin-embedded tissue can be challenging, with complicated procedures producing uncertain results and poor image quality. Here, we developed a robust RNA detection method based on graphene oxide (GO) quenching and recovery of fluorescence in situ hybridization (G-FISH) in formalin-fixed paraffin-embedded (FFPE) tissues. Using a fluorophore-labeled peptide nucleic acid (PNA) attached to GO, the endogenous long noncoding RNA BC1, the constitutive protein β-actin mRNA, and miR-124a and miR-21 could be detected in the cytoplasm of a normal mouse brain, primary cultured hippocampal neurons, an Alzheimer's disease model mouse brain, and glioblastoma multiforme tumor tissues, respectively. Coding and non-coding RNAs, either long or short, could be detected in deparaffinized FFPE or frozen tissues, as well as in clear lipid-exchanged anatomically rigid imaging/immunostaining-compatible tissue hydrogel (CLARITY)-transparent brain tissues. The fluorescence recovered by G-FISH correlated highly with the amount of miR-21, as measured by quantitative real time RT-PCR. We propose G-FISH as a simple, fast, inexpensive, and sensitive method for RNA detection, with a very low background, which could be applied to a variety of research or diagnostic purposes.
Lu J, Ji H, Tang H, Xu ZmicroRNA-124a suppresses PHF19 over-expression, EZH2 hyper-activation, and aberrant cell proliferation in human glioma.
Biochem Biophys Res Commun. 2018; 503(3):1610-1617 [PubMed
] Related Publications
Enhancer of Zeste 2 (EZH2) is the key enzymatic factor in Polycomb Repressive Complex 2 (PRC2), a transcriptional repressor which contributes to oncogenesis. Recent research has revealed the key role of aberrant EZH2 hyper-activity in human gliomas. Here, we examined the role of the lesser-known PRC2-associated PHD Finger Protein 19 (PHF19) in human glioma. We found that PHF19 transcript and protein levels were significantly elevated in human glioma tumors, which was negatively associated with expression of the anti-PHF19 microRNA miR-124a. miR-124a over-expression in the A172 and U251MG glioma cell lines and patient glioma cells suppressed PHF19 expression, EZH2 activation, and cell proliferation. However, miR-124a did not suppress cell proliferation with PHF19 silencing or mutation. Knockdown of PHF19 suppressed EZH2 phosphorylation and proliferation of glioma cells. Co-immunoprecipitation confirmed that PHF19 forms the PRC2 with EZH2, EED, and SUZ12. In a nude murine model, subcutaneous and orthotopic xenograft tumor growth was significantly inhibited by miRNA-124a or PHF19 shRNA. In conclusion, miR-124a suppresses PHF19 over-expression, EZH2 hyper-activation, and aberrant glioma cell proliferation. Targeting PHF19 via miR-124a agomir therapy may block aberrant EZH2 hyper-activity in these tumors.
Yu F, Liu JB, Wu ZJ, et al.Tumor suppressive microRNA-124a inhibits stemness and enhances gefitinib sensitivity of non-small cell lung cancer cells by targeting ubiquitin-specific protease 14.
Cancer Lett. 2018; 427:74-84 [PubMed
] Related Publications
Increasing evidence has shown that microRNAs (miRNAs) play a significant functional role by directly regulating respective targets in cancer stem cell (CSC)-induced non-small cell lung cancer (NSCLC) progression and resistance to therapy. In this study, we found that hsa-miR-124a was downregulated during spheroid formation of the NSCLC cell lines SPC-A1 and NCI-H1650 and NSCLC tissues compared with normal lung cells and tissues. Patients with lower hsa-miR-124a expression had shorter overall survival (OS) and progression free survival (PFS). Moreover, ubiquitin-specific protease 14 (USP14) was confirmed to be a direct target of hsa-miR-124a. Furthermore, concomitant low hsa-miR-124a expression and high USP14 expression were correlated with a shorter median OS and PFS in NSCLC patients. Cellular functional analysis verified that the tumor suppressor hsa-miR-124a negatively regulated cell growth and self-renewal, and promoted apoptosis and gefitinib sensitivity of lung cancer stem cells by suppressing its target gene USP14. Our results provide the first evidence that USP14 is a direct target of hsa-miR-124a, and that hsa-miR-124a inhibits stemness and enhances the gefitinib sensitivity of NSCLC cells by targeting USP14. Thus, hsa-miR-124a and USP14 may be useful as tumor biomarkers for the diagnosis and treatment of NSCLC.
Maeda M, Yamashita S, Shimazu T, et al.Novel epigenetic markers for gastric cancer risk stratification in individuals after Helicobacter pylori eradication.
Gastric Cancer. 2018; 21(5):745-755 [PubMed
] Related Publications
BACKGROUND: The risk stratification of healthy individuals after Helicobacter pylori eradication is an urgent issue. The assessment of aberrant DNA methylation accumulated in gastric tissues with normal appearance, which can reflect overall epigenomic damage, is a promising strategy. We aimed to establish novel epigenetic cancer risk markers for H. pylori-eradicated individuals.
METHODS: Gastric mucosa was collected from eight healthy volunteers without H. pylori infection (G1), 75 healthy individuals with gastric atrophy (G2), and 94 gastric cancer patients (G3) after H. pylori eradication. Genome-wide analysis was conducted using Infinium 450 K and differentially methylated probes were screened using large difference and iEVORA-based methods. Bisulfite pyrosequencing was used for validation.
RESULTS: Screening, using 8 G1, 12 G2, and 12 G3 samples, isolated 57 candidates unmethylated in G1 and differentially methylated in G3 compared with G2. Validation for nine candidate markers (FLT3, LINC00643, RPRM, JAM2, ELMO1, BHLHE22, RIMS1, GUSBP5, and ZNF3) in 63 G2 and 82 G3 samples showed that all of them had significantly higher methylation levels in G3 than in G2 (P < 0.0001). Their methylation levels were highly correlated, which indicated that they reflect overall epigenomic damage. The candidates had sufficient performance (AUC: 0.70-0. 80) and high odds ratios (5.43-23.41), some of which were superior to a previous marker, miR-124a-3. The methylation levels of our novel markers were not associated with gastric atrophy, gender, or age.
CONCLUSIONS: Novel epigenetic markers for gastric cancer risk optimized for H. pylori-eradicated individuals were established.
Background: MicroRNAs (miRs) are promising new therapeutics for glioblastoma. However, which miRs are most effective against glioblastomas and how these miRs should be delivered are major unanswered problems.
Methods: To identify potent antiglioma miRs, we selected 8 miRs based on a literature search and screened them against a panel of glioma stem cell (GSC) lines, representing all of the glioblastoma subtypes defined by The Cancer Genome Atlas. To address delivery, we tested the hypothesis that ex vivo cultured bone marrow-derived mesenchymal stem cells (MSCs) can package miRs into exosomes and that these engineered exosomes can systemically deliver antiglioma miRs to glioblastomas.
Results: Of the screened miRs, we identified miR-124a as the most effective antiglioma agent against GSCs. We then transduced MSCs with lentivirus vectors containing miR-124a and isolated vesicles from the medium. Electron microscopy, western blotting, and Nanosight proved that the isolated vesicles were exosomes. Quantitative PCR documented that these exosomes contained high levels of miR-124a, which was not present in control exosomes. In vitro treatment of GSCs with exosomes containing miR-124a (Exo-miR124) resulted in a significant reduction in viability and clonogenicity of GSCs compared with controls. In vivo treatment of mice harboring intracranial GSC267 with systemically delivered Exo-miR124 resulted in 50% of animals living long term. No evidence of tumor was present on histological analysis of the survivors. Mechanistic studies showed that miR-124a acts by silencing Forkhead box (FOX)A2, resulting in aberrant intracellular lipid accumulation.
Conclusion: MSCs can be used as natural biofactories to produce Exo-miR124, which is an effective antiglioma agent worthy of further clinical evaluation.
Xi WD, Liu YJ, Sun XB, et al.Bioinformatics analysis of RNA-seq data revealed critical genes in colon adenocarcinoma.
Eur Rev Med Pharmacol Sci. 2017; 21(13):3012-3020 [PubMed
] Related Publications
OBJECTIVE: RNA-seq data of colon adenocarcinoma (COAD) were analyzed with bioinformatics tools to discover critical genes in the disease. Relevant small molecule drugs, transcription factors (TFs) and microRNAs (miRNAs) were also investigated.
MATERIALS AND METHODS: RNA-seq data of COAD were downloaded from The Cancer Genome Atlas (TCGA). Differential analysis was performed with package edgeR. False positive discovery (FDR) < 0.05 and |log2 (fold change)|>1 were set as the cut-offs to screen out differentially expressed genes (DEGs). Gene coexpression network was constructed with package Ebcoexpress. GO enrichment analysis was performed for the DEGs in the gene coexpression network with DAVID. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was also performed for the genes with KOBASS 2.0. Modules were identified with MCODE of Cytoscape. Relevant small molecules drugs were predicted by Connectivity map. Relevant miRNAs and TFs were searched by WebGestalt.
RESULTS: A total of 457 DEGs, including 255 up-regulated and 202 down-regulated genes, were identified from 437 COAD and 39 control samples. A gene coexpression network was constructed containing 40 DEGs and 101 edges. The genes were mainly associated with collagen fibril organization, extracellular matrix organization and translation. Two modules were identified from the gene coexpression network, which were implicated in muscle contraction and extracellular matrix organization, respectively. Several critical genes were disclosed, such as MYH11, COL5A2 and ribosomal proteins. Nine relevant small molecule drugs were identified, such as scriptaid and STOCK1N-35874. Accordingly, a total of 17 TFs and 10 miRNAs related to COAD were acquired, such as ETS2, NFAT, AP4, miR-124A, MiR-9, miR-96 and let-7.
CONCLUSIONS: Several critical genes and relevant drugs, TFs and miRNAs were revealed in COAD. These findings could advance the understanding of the disease and benefit therapy development.
Previous studies have suggested that dysregulation of microRNA (miR) -124a is associated with various types of human cancer. However, there are few studies reporting the level of miR‑124a expression in non‑small cell lung cancer (NSCLC). The present study investigated the association between miR‑124a and NSCLC by analyzing the differential expression of miR‑124a in NSCLC using the GEO database, as well as subsequently performing reverse transcription‑quantitative polymerase chain reaction analysis on 160 NSCLC biopsies, 32 of which were paired with adjacent normal tissues. The results indicated that mir‑124a expression levels were decreased in NSCLC tumor biopsies compared with adjacent normal tissues. The overall survival (OS) in patients with a high expression of miR‑124a was prolonged relative to patients with low expression of miR‑124a. The expression levels of miR‑124a were associated with clinical characteristics, including lymph‑node metastasis, tumor differentiation, tumor node metastasis (TNM) stage and diameter. Frequently, lymph‑node metastasis, TNM stage, diameter and lack of chemotherapy have been associated with a worse prognosis in patients. In addition, the present study identified that high expression of miR‑124awith chemotherapy may increase OS. In conclusion, the current study demonstrated that miR‑124a was downregulated in NSCLC, and miR‑124a was a potential prognostic tumor biomarker response to chemotherapy.
The microRNA-200 (miR-200) family is associated with tumor metastasis and poor patient prognosis. We found that miR-200c/141 cluster overexpression upregulated SerpinB2 in the MDA-MB-231 triple-negative (TN) breast cancer cell line. We observed transcription factor (c-Jun, c-Fos, and FosB) upregulation, nuclear localization of c-Jun, and increased SerpinB2 promoter-directed chloramphenicol acetyltransferase activity in miR-200c/141 cluster-overexpressing cells relative to controls. Additionally, miR-124a and miR-26b, which directly target SepinB2, were downregulated compared to controls. In mouse xenograft models, miR-200c/141 cluster overexpression promoted lymph node and lung metastasis, and siRNA-mediated SerpinB2 knockdown decreased lung metastasis, suggesting that SerpinB2 mediates miR-200c/141-induced lung metastasis. We also explored the clinical significance of SerpinB2 protein status through analysis of primary breast tumor samples and The Cancer Genome Atlas (TCGA) data. High SerpinB2 levels were associated with reduced survival and increased lymph node metastasis in breast cancer patients. SerpinB2 was overexpressed in the TN breast cancer subtype as compared to the luminal subtype. The present study demonstrates that SerpinB2 promotes miR-200c/141 cluster overexpression-induced breast cancer cell metastasis, and SerpinB2 overexpression correlates with increased metastatic potential and unfavorable outcomes in breast cancer patients. SerpinB2 may be a useful biomarker for assessing metastasis risk in breast cancer patients.
Polymorphisms in miRNA and miRNA pathway genes have been previously associated with cancer risk and outcome, but have not been studied in esophageal adenocarcinoma outcomes. Here, we evaluate candidate miRNA pathway polymorphisms in esophageal adenocarcinoma prognosis and attempt to validate them in an independent cohort of esophageal adenocarcinoma patients. Among 231 esophageal adenocarcinoma patients of all stages/treatment plans, 38 candidate genetic polymorphisms (17 biogenesis, 9 miRNA targets, 5 pri-miRNA, 7 pre-miRNA) were genotyped and analyzed. Cox proportional hazard models adjusted for sociodemographic and clinicopathological covariates helped assess the association of genetic polymorphisms with overall survival (OS) and progression-free survival (PFS). Significantly associated polymorphisms were then evaluated in an independent cohort of 137 esophageal adenocarcinoma patients. Among the 231 discovery cohort patients, 86% were male, median diagnosis age was 64 years, 34% were metastatic at diagnosis, and median OS and PFS were 20 and 12 months, respectively. GEMIN3 rs197412 (aHR = 1.37, 95%CI: [1.04-1.80]; P = 0.02), hsa-mir-124-1 rs531564 (aHR = 0.60, 95% CI: [0.53-0.90]; P = 0.05), and KIAA0423 rs1053667 (aHR = 0.51, 95% CI: [0.28-0.96]; P = 0.04) were found associated with OS. Furthermore, GEMIN3 rs197412 (aHR = 1.33, 95% CI: [1.03-1.74]; P = 0.03) and KRT81 rs3660 (aHR = 1.29, 95% CI: [1.01-1.64]; P = 0.04) were found associated with PFS. Although none of these polymorphisms were significant in the second cohort, hsa-mir-124-1 rs531564 and KIAA0423 rs1053667 had trends in the same direction; when both cohorts were combined together, GEMIN3 rs197412, hsa-mir-124-1 rs531564, and KIAA0423 rs1053667 remained significantly associated with OS. We demonstrate the association of multiple miRNA pathway polymorphisms with esophageal adenocarcinoma prognosis in a discovery cohort of patients, which did not validate in a separate cohort but had consistent associations in the pooled cohort. Larger studies are required to confirm/validate the prognostic value of these polymorphisms in esophageal adenocarcinoma.
Shi ZW, Wang JL, Zhao N, et al.Single nucleotide polymorphism of hsa-miR-124a affects risk and prognosis of osteosarcoma.
Cancer Biomark. 2016; 17(2):249-57 [PubMed
] Related Publications
OBJECTIVE: To study the correlation between single nucleotide polymorphism (SNP) of hsa-miR-124a and risk and prognosis of osteosarcoma (OS).
METHODS: OS patients (n = 174) hospitalized at The Second Affiliated Hospital of Harbin Medical University from January 2010 to March 2012 were selected as case group by inclusion and exclusion criteria, and healthy people (n = 150) receiving physical examination at the same duration were recruited as control group. Polymerase chain reaction-ligase detection reaction (PCR-LDR) was performed for genotyping of hsa-miR-124a rs531564.
RESULTS: There were significant differences in the frequency distribution of genotypes and alleles of hsa-miR-124a rs531564 in the case and control group (all P < 0.05); the individuals carrying with CG + GG genotype showed significantly decreased risk for OS. The clinical pathological characteristics were significantly different in the patients with CC genotype and CG + GG genotype, including tumor size, tumor differentiation grading, Enneking staging, operation manner, time of chemotherapy and metastasis (all P < 0.05). The 5-year survival rate of the cases with CC genotype was significantly lower than that of the ones with CG + GG genotype (P < 0.05). CG + GG genotype, Enneking staging and operation manner were independent risk factors for prognosis of OS (all P < 0.05).
CONCLUSIONS: CG +$ GG genotype of hsa-miR-124a rs531564 had decreased risk for OS and affected prognosis of OS.
Zhang S, Guo LJ, Zhang G, et al.Roles of microRNA-124a and microRNA-30d in breast cancer patients with type 2 diabetes mellitus.
Tumour Biol. 2016; 37(8):11057-63 [PubMed
] Related Publications
The aim of the study is to explore roles of microRNA (miR)-124a and miR-30d in breast cancer (BC) patients with type 2 diabetes mellitus (T2DM). A total of 144 cases of confirmed diagnosed BC with T2DM, T2DM, BC, or healthy people were enrolled. Among them, BC patients with T2DM were regarded as the experiment group (n = 36), patients with T2DM as the Dm group (n = 36), patients with BC as the Bc group (n = 36), and healthy subjects as the healthy group (n = 36). The fasting insulin resistance index, glycosylated hemoglobin, and estradiol were measured. MiR-124a and miR-30d expressions were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The insulin resistance index was significantly higher in the experiment group compared to the other three groups (all P < 0.05). The glycated hemoglobin was in a normal range in the Bc group and healthy group, but was higher in the experiment group and the Bc group compared to that in the healthy group (both P < 0.05). The serum estradiol level was obviously higher in the Bc group compared with that in the Dm group and the experiment group (both P < 0.05). The expressions of miR-124a and miR-30d were positively correlated with insulin resistance index, BMI and glycosylated hemoglobin (miR-124a r = 0.659, r = 0.785, and r = 0.862; miR-30d r = 0.742, r = 0.805, r = 0.765; all P < 0.001). Insulin resistance index was an independent factor for expressions of miR124-a and miR-30d. MiR-124a and miR-30d were correlated with insulin resistance and development of BC with T2DM. Although the mechanism is not clear, miR-124a and miR-30d potentially may be used as therapeutic targets and prognostic markers for BC patients with T2DM.
Human T-cell leukemia virus type 1 (HTLV-1)-associated adult T-cell leukemia and T-cell lymphoma (ATL) are aggressive diseases with poor prognoses, limited therapeutic options, and no curative treatment. In this study, we used a mouse model of ATL and restored expression of the microRNA, miR-124a, to identify in vivo downstream effectors responsible for its tumor-suppressive functions in ATL cells. Our results revealed that STAT3, a direct target of miR-124a, is constitutively activated in HTLV-I-transformed cells and ATL cells, and activating STAT3 mutations were detected in 25.5% of primary ATL patients. Interestingly, we found that the STAT3 downstream kinase effector, Pim1, is constitutively activated in ATL cells. The dependence of ATL cells to Pim1 activity was demonstrated using 2 Pim1 small inhibitors, SMI-4a and AZD1208. These studies indicated that HTLV-I-transformed and ATL cells, but not normal peripheral blood mononuclear cells, are highly sensitive to AZD1208, and the inhibition of Pim1 signaling triggers an apoptotic signal in leukemic cells. Finally, preclinical testing of AZD1208 in a mouse model of ATL resulted in significant prevention of tumor growth in vivo. In conclusion, our studies suggest that constitutive activation of the STAT3-Pim1 pathway represents a novel therapeutic target for the treatment of ATL.
Shimazu T, Asada K, Charvat H, et al.Association of gastric cancer risk factors with DNA methylation levels in gastric mucosa of healthy Japanese: a cross-sectional study.
Carcinogenesis. 2015; 36(11):1291-8 [PubMed
] Related Publications
Helicobacter pylori infection induces aberrant DNA methylation, and methylation levels of several specific marker genes in gastric mucosa are associated with gastric cancer risk. However, it is unclear whether gastric cancer risk factors are associated with methylation levels of marker genes in healthy individuals. We conducted a cross-sectional study of 281 Japanese cancer screenees aged 40-69 years with no history of H.pylori eradication therapy who responded to a validated food frequency questionnaire. DNA methylation levels of marker genes (miR-124a-3, EMX1 and NKX6-1) in gastric mucosa were quantified by real-time methylation-specific polymerase chain reaction. A multivariate beta regression model was used to investigate the association of pack-years of smoking and intakes of green/yellow vegetables, fruit and salt with methylation levels of marker genes. All analyses were stratified by H.pylori status. We found 2.5 to 34.1 times higher mean methylation levels among those with current H.pylori infection (n = 117) compared to those without (n = 164). After adjustment for potential confounders, we found increased levels of miR-124a-3 methylation according to pack-years of smoking and decreased levels of methylation according to green/yellow vegetable intake. We did not detect these associations among those without H.pylori infection. In conclusion, smoking habits and green/yellow vegetable intake were associated with DNA methylation levels in gastric mucosae of healthy individuals with current H.pylori infection. Our study suggests that these risk factors may modify the effect of H.pylori on methylation induction and maintenance in gastric mucosa.
Xue F, Shen R, Chen XAnalysis of gene profiles in glioma cells identifies potential genes, miRNAs, and target sites of migratory cells.
Tumori. 2015 Sep-Oct; 101(5):542-8 [PubMed
] Related Publications
AIMS: To explore the potential molecular mechanisms involved in migratory glioma cells.
METHODS: The gene expression profiles of GSE28167, employing human malignant glioma U251MG cells cultured on strictly aligned versus randomly oriented electrospun nanofibers of polycaprolactone, were downloaded from the Gene Expression Omnibus database. Gene differential expression analysis was carried out by the package of Gene Expression Omnibus query and limma in R language. The Gene Set Analysis Toolkit V2 was used for pathway analysis. Gene set enrichment analysis was used to screen for target sites of transcription factors, miRNA and small drug molecules.
RESULTS: Totally 586 differentially expressed genes were identified and the differentially expressed genes were mainly enriched in the pathway of muscle cell TarBase, MAPK cascade, adipogenesis and epithelium TarBase. Thirty-two significant target sites of transcription factors, such as hsa_RTAAACA_V$FREAC2_01, were screened. The top 20 potential miRNAs including MIR-124A, MIR-34A and MIR-34C were screened for a constructing gene-miRNA interaction network. Small molecules that can inhibit the motility of glioma cells such as diclofenamide and valinomycin were mined. By integrating the regulatory relationships among transcription factors, miRNAs and differentially expressed genes, we found that 7 differentially expressed genes, including SOX4, ANKRD28 and CCND1, might play crucial roles in the migration of glioma cells.
CONCLUSIONS: The screened migration-associated genes, significant pathways, and small molecules give us new insight for the mechanism of migratory glioma cells. Interest in such genes as potential target genes in the treatment of glioblastoma justifies functional validation studies.
High-risk human papillomavirus (hrHPV)-induced immortalization and malignant transformation are accompanied by DNA methylation of host genes. To determine when methylation is established during cell immortalization and whether it is hrHPV-type dependent, DNA methylation was studied in a large panel of HPVE6E7-immortalized keratinocyte cell lines. These cell lines displayed different growth behaviors, i.e., continuous growth versus crisis period prior to immortalization, reflecting differential immortalization capacities of the 7 HPV-types (16/18/31/33/45/66/70) studied. In this study, cells were monitored for hypermethylation of 14 host genes (APC, CADM1, CYGB, FAM19A4, hTERT, mir124-1, mir124-2, mir124-3, MAL, PHACTR3, PRDM14, RASSF1A, ROBO3, and SFRP2) at 4 different stages during immortalization. A significant increase in overall methylation levels was seen with progression through each stage of immortalization. At stage 1 (pre-immortalization), a significant increase in methylation of hTERT, mir124-2, and PRDM14 was already apparent, which continued over time. Methylation of ROBO3 was significantly increased at stage 2 (early immortal), followed by CYGB (stage 3) and FAM19A4, MAL, PHACTR3, and SFRP2 (stage 4). Methylation patterns were mostly growth behavior independent. Yet, hTERT methylation levels were significantly increased in cells that just escaped from crisis. Bisulfite sequencing of hTERT confirmed increased methylation in immortal cells compared to controls, with the transcription core and known repressor sites remaining largely unmethylated. In conclusion, HPV-induced immortalization is associated with a sequential and progressive increase in promoter methylation of a subset of genes, which is mostly independent of the viral immortalization capacity.
BACKGROUND: Epigenetic alterations accumulate in normal-appearing tissues of patients with cancer, producing an epigenetic field defect. Cross-sectional studies show that the degree of the defect may be associated with risk in some types of cancer, especially cancers associated with chronic inflammation.
OBJECTIVE: To demonstrate, by a multicentre prospective cohort study, that the risk of metachronous gastric cancer after endoscopic resection (ER) can be predicted by assessment of the epigenetic field defect using methylation levels.
DESIGN: Patients with early gastric cancer, aged 40-80 years, who planned to have, or had undergone, ER, were enrolled at least 6 months after Helicobacter pylori infection discontinued. Methylation levels of three preselected genes (miR-124a-3, EMX1 and NKX6-1) were measured by quantitative methylation-specific PCR. Patients were followed up annually by endoscopy, and the primary endpoint was defined as detection of a metachronous gastric cancer. Authentic metachronous gastric cancers were defined as cancers excluding those detected within 1 year after the enrolment.
RESULTS: Among 826 patients enrolled, 782 patients had at least one follow-up, with a median follow-up of 2.97 years. Authentic metachronous gastric cancers developed in 66 patients: 29, 16 and 21 patients at 1-2, 2-3 and ≥3 years after the enrolment, respectively. The highest quartile of the miR-124a-3 methylation level had a significant univariate HR (95% CI) (2.17 (1.07 to 4.41); p=0.032) and a multivariate-adjusted HR (2.30 (1.03 to 5.10); p=0.042) of developing authentic metachronous gastric cancers. Similar trends were seen for EMX1 and NKX6-1.
CONCLUSIONS: Assessment of the degree of an epigenetic field defect is a promising cancer risk marker that takes account of life history.
Lu SH, Jiang XJ, Xiao GL, et al.miR-124a restoration inhibits glioma cell proliferation and invasion by suppressing IQGAP1 and β-catenin.
Oncol Rep. 2014; 32(5):2104-10 [PubMed
] Related Publications
A number of microRNAs have been identified to be important regulators of tumorigenesis. Previous research has shown that miR-124 is abundantly expressed in normal brain tissue; however, only a few reports have focused on the biological impact of miR-124 on glioma cells, and the underlying mechanisms need to be elucidated. Therefore, we investigated the effect of miR-124a on glioma cell proliferation and invasion; furthermore, the underlying molecular mechanism was examined. The present study demonstrated that miR-124a expression was downregulated in human glioma tissues, and its expression level was negatively correlated with the pathological grade of the glioma. Restoration of miR-124a inhibited glioma cell proliferation and invasion in vitro. Furthermore, we found that miR-124a directly targeted and suppressed IQ motif containing GTPase activating protein 1 (IQGAP1), a well-known regulator of actin dynamics and cell motility. RNA interference assay showed that IQGAP1 knockdown led to downregulation of β-catenin and downstream cyclin D1. Taken together, our study revealed that miR-124a could inhibit glioma cell proliferation and invasion by blocking the expression of the IQGAP1 gene and downstream β-catenin and cyclin D1. This research may provide a useful molecular therapy for gliomas.
BACKGROUND: B7-H3, an immunoregulatory protein, is overexpressed in several cancers and is often associated with metastasis and poor prognosis. Here, our aim was to identify microRNAs (miRNAs) regulating B7-H3 and assess their potential prognostic implications in breast cancer.
METHODS: MicroRNAs targeting B7-H3 were identified by transfecting two breast cancer cell lines with a library of 810 miRNA mimics and quantifying changes of B7-H3 protein levels using protein lysate microarrays. For validations we used western immunoblotting and 3'-UTR luciferase assays. Clinical significance of the miRNAs was assayed by analysing whether their expression levels correlated with outcome in two cohorts of breast cancer patients (142 and 81 patients).
RESULTS: We identified nearly 50 miRNAs that downregulated B7-H3 protein levels. Western immunoblotting validated the impact of the 20 most effective miRNAs. Thirteen miRNAs (miR-214, miR-363*, miR-326, miR-940, miR-29c, miR-665, miR-34b*, miR-708, miR-601, miR-124a, miR-380-5p, miR-885-3p, and miR-593) targeted B7-H3 directly by binding to its 3'-UTR region. Finally, high expression of miR-29c was associated with a significant reduced risk of dying from breast cancer in both cohorts.
CONCLUSIONS: We identified miRNAs efficiently downregulating B7-H3 expression. The expression of miR-29c correlated with survival in breast cancer patients, suggesting a tumour suppressive role for this miRNA.
Ben Gacem R, Ben Abdelkrim O, Ziadi S, et al.Methylation of miR-124a-1, miR-124a-2, and miR-124a-3 genes correlates with aggressive and advanced breast cancer disease.
Tumour Biol. 2014; 35(5):4047-56 [PubMed
] Related Publications
Aberrant DNA methylation on CpG islands is one of the most consistent epigenetic changes in human cancers, and the process of methylation is catalyzed by the DNA methyltransferases DNMT1, DNMT3a, and DNMT3b. Recent reports demonstrate that deregulation of miR-124a, one of the frequently methylated microRNAs in human cancers, is related to carcinogenesis. The aim of this study was to evaluate the frequencies of methylation of the three genomic loci encoding the miR-124a in primary breast cancers and to investigate their relationships with the clinicopathological characteristics of the tumors and with the expression levels of DNMT1, DNMT3a, and DNMT3b. The methylation status of the three genomic loci encoding the miR-124a (miR-124a-1, miR-124a-2, and miR-124a-3) was analyzed in fresh-frozen tumor samples using methylation-specific PCR in a large series of invasive breast ductal carcinomas (n = 60). Results were correlated to several clinicopathological characteristics of the tumors and to the expression levels of DNMT1, DNMT3a, and DNMT3b, determined by immunohistochemistry. Promoter hypermethylation of miR-124a-1, miR-124a-2, and miR-124a-3 was detected in 53.3, 70, and 36.7% of cases, respectively. Methylation of miR-124a-2 correlated to patients with age higher than 45 years (P = 0.008) and to postmenopausal patients (P = 0.03), whereas methylation of miR-124a-3 correlated significantly to tumor size >20 mm (P = 0.03). Interestingly, simultaneous methylation of the three genes encoding miR-124a correlated significantly with the presence of lymph node metastasis (P = 0.01) and high mitotic score (P = 0.03). No significant correlation was found between promoter hypermethylation of miR-124a and expression of hormone receptors or HER2/neu. With regard to DNMT expression, no correlation was found between DNMT1 or DNMT3a expression and promoter methylation of any tested microRNA. However, DNMT3b overexpression correlates significantly with the hypermethylation of miR-124a-3 (P = 0.03). Our data indicates that miR-124a-1, miR-124a-2, and miR-124a-3 genes are frequently methylated in breast cancer and play a role in tumor growth and aggressivity.
Liang S, Chen L, Huang H, Zhi DThe experimental study of miRNA in pituitary adenomas.
Turk Neurosurg. 2013; 23(6):721-7 [PubMed
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AIM: We investigated the differential miRNA expression in pituitary adenomas (both non-functioning and gonadotropin-secreting) and normal pituitaries.
MATERIAL AND METHODS: RNA was extracted and purified from pituitary adenomas (10 non-functioning and 10 gonadotropin-secreting) and from two normal pituitary tissue samples. The samples were analyzed by miRNA microarray. Gene expression was measured using realtime RT-PCR with SYBR GREEN I.
RESULTS: In non-functioning pituitary adenomas, 25 miRNA genes were up-regulated (six by over 5-fold) and 15 were down-regulated (six by more than 10-fold). miR-124a was the most up-regulated gene (38.58-fold), and miR-31 the most down-regulated gene (21.5-fold). In gonadotropin-secreting pituitary adenomas, 16 miRNA genes were up-regulated (six by over 4-fold) and 13 were down-regulated (seven by more than 10-fold). miR-10b was the most up-regulated gene (48.73-fold), and miR-503 the most down-regulated gene (39.8-fold). Five genes were up-regulated in both subtypes: miR-523, miR-10b, miR-520b, miR-422a, and miR-422b. The RT-PCR results were consistent with those of the gene chips.
CONCLUSION: We established miRNA expression maps of non-functioning and gonadotropin-secreting pituitary adenomas. The most strongly differentially expressed genes were miR-124a and miR-31 in non-functioning pituitary adenomas, and miR-10b and miR-503 in gonadotropin-secreting pituitary adenomas.
Tivnan A, Zhao J, Johns TG, et al.The tumor suppressor microRNA, miR-124a, is regulated by epigenetic silencing and by the transcriptional factor, REST in glioblastoma.
Tumour Biol. 2014; 35(2):1459-65 [PubMed
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Reduced levels of specific microRNA in cancer are frequently reported and associated with attenuated cancer genes and associated pathways. We previously reported a loss of miR-124a in glioblastoma (GBM) patient specimens; however, the upstream causes of this loss are largely unknown. Loss of miR-124a has been attributed to hypermethylation while other studies have shown miR-124a to be regulated by the repressor-element-1-silencing transcription factor (REST, also known as neuron-restrictive silencing factor). This current study looked at both epigenetic and transcription factor regulation as potential mechanisms resulting in the loss of miR-124a expression in GBM patient specimens and cell lines. Hypermethylation of miR-124a was observed in 82 % of GBM patient specimens (n = 56). In vitro miR-124a expression levels also increased after treatment of several patient-derived cell lines with 5-aza-2'-deoxycytidine. Additionally, we also demonstrated a positive interaction between REST activity and miR-124a using a luciferase-binding assay and we correlated the reciprocal expression of REST and miR-124a in our clinical cohort. This result indicates that miR-124a expression may also be modulated through the upstream targeting of REST. Preclinical studies involving inhibitors of REST and treatment with demethylating agents with the intent to increase miR-124a levels could be interesting.
MicroRNAs (miRNAs) are a small class of non‑coding RNAs that negatively regulate gene expression, and are considered as new therapeutic targets for treating cancer. In this study, we performed a gain-of-function screen using miRNA mimic library (319 miRNA species) to identify those affecting cell proliferation in human epithelial ovarian cancer cells (A2780). We discovered a number of miRNAs that increased or decreased the cell viability of A2780 cells. Pro-proliferative and anti-proliferative miRNAs include oncogenic miR-372 and miR-373, and tumor suppressive miR-124a, miR-7, miR-192 and miR-193a, respectively. We found that overexpression of miR-124a, miR-192, miR-193a and miR‑193b inhibited BrdU incorporation in A2780 cells, indicating that these miRNAs affected the cell cycle. Overexpression of miR‑193a and miR-193b induced an activation of caspase 3/7, and resulted in apoptotic cell death in A2780 cells. A genome‑wide gene expression analysis with miR-193a-transfected A2780 cells led to identification of ARHGAP19, CCND1, ERBB4, KRAS and MCL1 as potential miR-193a targets. We demonstrated that miR-193a decreased the amount of MCL1 protein by binding 3'UTR of its mRNA. Our study suggests the potential of miRNA screens to discover miRNAs as therapeutic tools to treat ovarian cancer.
BACKGROUND: MIR129-2 has been shown to be a tumor suppressor microRNA hypermethylated in epithelial cancers.
PATIENTS AND METHODS: Epigenetic inactivation of MIR129-2 was studied by methylation-specific PCR (MSP) in 13 cell lines (eight myeloma and five lymphoma), 15 normal controls and 344 primary samples including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), chronic lymphocytic leukemia (CLL), non-Hodgkin's lymphoma (NHL), multiple myeloma (MM) at diagnosis, MM at relapse/progression, and monoclonal gammopathy of undetermined significance (MGUS). Expression of MIR129 and its target, SOX4, in cell lines was measured before and after hypomethylating treatment and MIR129 overexpression. MIR129 expression was correlated with MIR129-2 methylation status in primary lymphoma samples. Tumor suppressor function of MIR129 was demonstrated by MTT and trypan blue exclusion assay after MIR129 overexpression.
RESULTS: The sensitivity of the methylated-MSP was one in 10(3). Different MSP statuses, including complete methylation, partial methylation, and complete unmethylation, were verified by quantitative bisulfite pyrosequencing. All five lymphoma and seven of eight myeloma cell lines showed complete and partial MIR129-2 methylation. In primary samples, MIR129-2 methylation was absent in AML and CML, but detected in 5% ALL, 45.9% CLL, 49.5% MM at diagnosis, and 59.1% NHL. In CLL, MIR129-2 methylation adversely impacted on survival (p=0.004). In MM, MIR129-2 methylation increased from 27.5% MGUS to 49.5% MM at diagnosis and 41.5% at relapse/progression (p=0.023). In NHL, MIR129-2 methylation was associated with MIR124-1 and MIR203 methylation (p<0.001), and lower MIR129 expression (p=0.009). Hypomethylation treatment of JEKO-1, homozygously methylated for MIR129-2, led to MIR129-2 demethylation and MIR129 re-expression, with downregulation of SOX4 mRNA. Moreover, MIR129 overexpression in both mantle cell lines, JEKO-1 and GRANTA-519, inhibited cellular proliferation and enhanced cell death, with concomitant SOX4 mRNA downregulation.
CONCLUSIONS: MIR129-2 is a tumor suppressive microRNA frequently methylated in lymphoid but not myeloid malignancies, leading to reversible MIR129-2 silencing. In CLL, MIR129-2 methylation was associated with an inferior survival. In MM, MIR129-2 methylation might be acquired during progression from MGUS to symptomatic MM. In NHL, MIR129-2 methylation might collaborate with MIR124-1 and MIR203 methylation in lymphomagenesis.
Chen X, He D, Dong XD, et al.MicroRNA-124a is epigenetically regulated and acts as a tumor suppressor by controlling multiple targets in uveal melanoma.
Invest Ophthalmol Vis Sci. 2013; 54(3):2248-56 [PubMed
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PURPOSE: MicroRNA-124a (miR-124a), an abundant microRNA in the central neuron system, has been linked to tumor progression. Here, we investigated the role of miR-124a in uveal melanoma development.
METHODS: Expression of miR-124a in uveal melanoma cells was examined using real time RT-PCR. The effect of miR-124a on cell proliferation, migration, and invasion was analyzed using MTS assay, flow cytometry, and transwell experiments. The ability of miR-124a to repress tumor growth was tested in vivo. Target genes of miR-124a were first predicted by bioinformatics, confirmed using a luciferase assay, and their expression determined by Western blotting. DNA methylation and histone modification of miR-124a was analyzed by methylation-specific PCR and ChIP assay. Finally, epigenetic drugs were used to alter the expression of miR-124a.
RESULTS: miR-124a expression was downregulated in both uveal melanoma cells and clinical specimens. Transient transfection of miR-124a into uveal melanoma cells inhibited cell growth, migration, and invasion. Moreover, introduction of miR-124a suppressed in vivo growth of tumor. Potential targets of miR-124a were found to include CDK4, CDK6, cyclin D2, and EZH2. Knockdown of EZH2 by siRNA resulted in inhibition of uveal melanoma cell migration and invasion. In addition, miR-124a expression was found to be regulated via epigenetic mechanisms, with its expression restored when cells were treated with a DNA hypomethylating agent, 5-aza-2'-deoxycytidine, and a histone deacetylase inhibitor, trichostatin A.
CONCLUSIONS: Our results demonstrated that miR-124a could function as a potent tumor suppressor by regulation of multiple targets, and was epigenetically silenced in the development of uveal melanoma.
Anwar SL, Albat C, Krech T, et al.Concordant hypermethylation of intergenic microRNA genes in human hepatocellular carcinoma as new diagnostic and prognostic marker.
Int J Cancer. 2013; 133(3):660-70 [PubMed
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Epigenetic inactivation by aberrant DNA methylation has been reported for many microRNA genes in various human malignancies. However, relatively little is known about microRNA gene methylation in hepatocellular carcinoma (HCC). Therefore, a systematic screen for identification of aberrantly hypermethylated microRNA genes in HCC was initiated. The methylation status of 39 intergenic CpG island associated microRNA genes was analyzed in HCC cell lines (n = 7), immortalized hepatocytes (n = 2) and normal liver samples (n = 5). Subsequently, 13 differentially methylated microRNA genes were analyzed in primary human HCC samples (n = 40), benign liver tumors (n = 15) and the adjacent liver tissues employing pyrosequencing. Expression of microRNA genes was measured using quantitative real-time polymerase chain reaction (RT-PCR). In addition, DNA methylation and expression of microRNA genes were measured after DNMT1 knockdown or DNMT inhibition. Aberrant hypermethylation and concomitant reduction in expression of intergenic microRNA genes is a frequent event in human HCC: hsa-mir-9-2 (23%), hsa-mir-9-3 (50 %), hsa-mir-124-1 (20%), hsa-mir-124-2 (13%), hsa-mir-124-3 (43%), hsa-mir-129-2 (58%), hsa-mir-596 (28%) and hsa-mir-1247 (38%). Altogether, it affects 90% of the HCC specimens under study. MicroRNA gene methylation is not found in hepatocellular adenoma (n = 10) and focal nodular hyperplasia (n = 5). DNMT1 knockdown or DNMT inhibition reduced microRNA gene methylation and stimulated expression. In primary human HCC specimens hypermethylation and expression of microRNA genes showed an inverse correlation. Concordant hypermethylation of three or more microRNA genes is a highly specific marker for the detection of HCC and for poor prognosis.
Thorns C, Kuba J, Bernard V, et al.Deregulation of a distinct set of microRNAs is associated with transformation of gastritis into MALT lymphoma.
Virchows Arch. 2012; 460(4):371-7 [PubMed
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The mechanisms underlying the transformation from chronic Helicobacter pylori gastritis to gastric extranodal marginal zone lymphoma (MALT lymphoma) are poorly understood. This study aims to identify microRNAs that might be involved in the process of neoplastic transformation. We generated microRNA signatures by RT-PCR in 68 gastric biopsy samples representing normal mucosa, gastritis, suspicious lymphoid infiltrates, and overt MALT lymphoma according to Wotherspoon criteria. Analyses revealed a total of 41 microRNAs that were significantly upregulated (n = 33) or downregulated (n = 8) in succession from normal mucosa to gastritis and to MALT lymphoma. While some of these merely reflect the presence of lymphocytes (e.g. miR-566 and miR-212) or H. pylori infection (e.g. miR-155 and let7f), a distinct set of five microRNAs (miR-150, miR-550, miR-124a, miR-518b and miR-539) was shown to be differentially expressed in gastritis as opposed to MALT lymphoma. This differential expression might therefore indicate a central role of these microRNAs in the process of malignant transformation.
Stanley JA, Aruldhas MM, Chandrasekaran M, et al.Androgen receptor expression in human thyroid cancer tissues: a potential mechanism underlying the gender bias in the incidence of thyroid cancers.
J Steroid Biochem Mol Biol. 2012; 130(1-2):105-24 [PubMed
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Gender bias in the incidence of thyroid cancer is well known, however, the underlying mechanism is largely unknown. The current study determines variations in the molecular characteristics of thyroid cancers between men and women. Normal and cancerous thyroid tissues were collected from a total of 125 men and women who underwent surgical thyroidectomy. Testosterone levels in serum and thyroid cancer tissues were elevated in women while it decreased in men compared to respective control groups; whereas, ligand binding activity increased in men and decreased in women. Androgen receptor (AR) mRNA expression increased in a majority of men while it decreased in a majority of women except those with follicular thyroid carcinoma (FTC). In thyroid cancers of women, Pearson's correlation analysis showed a positive correlation of AR mRNA with AR protein, CBP and Sp1, whereas AR mRNA showed a negative correlation with p53. In case of men, AR mRNA showed a positive correlation with AR and cyclin D1 proteins in papillary thyroid carcinoma (PTC); and CBP and Sp1 in follicular thyroid adenoma (FTA), whereas AR mRNA showed a positive correlation with p53. Our study identified for the first time that AR is posttranscriptionally regulated by miR-124a in thyroid cancer tissues. Further, our in vitro studies with a PTC cell line (NPA-87-1) showed miR-124a as the potent inhibitor of AR that impairs cell proliferation even in the presence of testosterone. Thus, the current study suggests that: (i) the varying pattern of testosterone level and AR status in thyroid tissues of men and women may predispose to the gender specific incidence of thyroid tumors and (ii) miR-124a plays a significant role in determining the AR gene expression pattern and thus, androgen mediated thyroid tumor growth.
Lau KM, Chan QK, Pang JC, et al.Overexpression of HMGA1 deregulates tumor growth via cdc25A and alters migration/invasion through a cdc25A-independent pathway in medulloblastoma.
Acta Neuropathol. 2012; 123(4):553-71 [PubMed
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Overexpression of high mobility group AT-hook 1 (HMGA1) is common in human cancers. Little is known about the mechanisms underlying its deregulation and downstream targets, and information about its clinical and biological significance in medulloblastoma (MB) is lacking. Here, we demonstrated frequent genomic gain at 6p21.33-6p21.31 with copy number increase leading to overexpression of HMGA1 in MB. The overexpression correlated with a high proliferation index and poor prognosis. Moreover, we found that hsa-miR-124a targeted 3'UTR of HMGA1 and negatively modulated the expression in MB cells, indicating that loss/downregulation of hsa-miR-124a reported in our previous study could contribute to the overexpression. Regarding the biological significance of HMGA1, siRNA knockdown and ectopic expression studies revealed the crucial roles of HMGA1 in controlling MB cell growth and migration/invasion through modulation of apoptosis and formation of filopodia and stress fibers, respectively. Furthermore, we identified cdc25A as a target of HMGA1 and showed that physical interaction between HMGA1 and the cdc25A promoter is required for transcriptional upregulation. In clinical samples, HMGA1 and cdc25A were concordantly overexpressed. Functionally, cdc25A is involved in the HMGA1-mediated control of MB cell growth. Finally, netropsin, which competes with HMGA1 in DNA binding, reduced the expression of cdc25A by suppression of its promoter activity and inhibited in vitro and in vivo intracranial MB cell growth. In conclusion, our results delineate the mechanisms underlying the deregulation and reveal the functional significance of HMGA1 in controlling MB cell growth and migration/invasion. Importantly, the results highlight the therapeutic potential of targeting HMGA1 in MB patients.
MicroRNAs (miRNAs) are recognized as being central players in many biological processes and cellular pathways. Their roles in disease have been highlighted first by observation of their aberrant expression profiles in human tumors, and then by in vitro and in vivo functional studies in transformed cells and model organisms. One of the most commonly observed features of miRNAs in malignancies is a defect in their production. Although several causes may be associated with this phenomenon, such as upstream oncogenic/tumor-suppressor defects and alterations in the miRNA-processing machinery, epigenetic inactivation is the prime suspect. The number of miRNAs with putative growth-inhibitory functions undergoing promoter CpG island hypermethylation in human cancer is growing fast and more detailed biological studies are necessary. The recognition of miR-124a and miR-34b/c as bona fide tumor-suppressor miRNAs undergoing DNA methylation-associated silencing in a wide spectrum of human neoplasms is a good starting point to be followed by other candidate miRNAs. Most importantly, even at this early stage, the transcriptional repression of miRNAs by hypermethylation of their corresponding promoter loci seems to be a common feature of all human tumors. This will have translational consequences for the management of the disease.
Botezatu A, Goia-Rusanu CD, Iancu IV, et al.Quantitative analysis of the relationship between microRNA‑124a, -34b and -203 gene methylation and cervical oncogenesis.
Mol Med Rep. 2011 Jan-Feb; 4(1):121-8 [PubMed
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Cervical cancer is a leading cause of mortality in women. Molecular and epidemiological data have unequivocally confirmed that high-risk human papillomaviruses (HPVs) are a major etiological agent of this malignancy, as host epigenetic alterations are induced in response to viral infection. The present study evaluated the methylation status of CpG islands surrounding miR-124a, miR-34b and miR-203 in 29 cervical cancer precursor lesions, 31 cervical tumors and 30 normal control samples, with the aim of identifying potential markers of cervical cancer. Direct quantitative methylation-specific PCR (qMSP) was used to evaluate the degree of methylation in the samples. HPV DNA was detected and genotyped using the Linear Array HPV Genotyping Test. Data were statistically analyzed using the Kruskal-Wallis test. Differences in miRNA hypermethylation between the tumor and control samples were highly significant for all the genes tested (p<0.0001). Significant results were also obtained regarding the hypermethylation of miR-124a and miR-203 in the precursor lesions compared to the control samples. Among the 29 patients with precursor lesions, 68.97% (20/29) presented high risk (hr)-HPV genotypes and 31.03% (9/29) were diagnosed with low risk (lr)-HPV. Significant results (p=0.0266) were obtained for miR-124a (hr-HPV group, mean 41.32; lr-HPV group, mean 6.74), revealing a strong association between the methylation process and the hr-HPV genotype. Borderline results (p=0.058) were obtained for miR-203 (hr-HPV group, mean 44.05; lr-HPV group, mean 3.33). These results confirm the involvement of epigenetic alterations in cervical oncogenesis. The lr-HPV precursor lesions had a methylation percent pattern similar to that of the normal samples, while the results for the hr-HPV precursor lesions and tumors indicate a possible involvement of the hr-HPV genotype in the miRNA methylation process.