Genome-wide microRNA expression profiling identifies miR-9-3 and miR-193a as targets for DNA methylation in non-small cell lung cancers
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ABSTRACT: Purpose: The major aim of this study was to investigate the role of DNA methylation (referred to as methylation) on microRNA (miRNA) silencing in non-small cell lung cancers (NSCLC). Experimental Design: We performed microarray expression analyses of 856 miRNAs in NSCLC A549 cells before and after treatment with the DNA methyltransferase inhibitor 5-aza-2´-deoxycytidine (Aza-dC) and with a combination of Aza-dC and the histone deacetylase inhibitor trichostatin A. MiRNA methylation was determined in 11 NSCLC cell lines and in primary tumors and corresponding non-malignant lung tissue samples of 101 stage I-III NSCLC patients. Results: By comparing microarray data of untreated and drug treated A549 cells, we identified 33 miRNAs whose expression was upregulated after drug treatment and which are associated with a CpG island. Thirty (91%) of these miRNAs were found to be methylated in at least 1 of 11 NSCLC cell lines analysed. Moreover, miR-9-3 and miR-193a were found to be tumor-specifically methylated in NSCLC patients. We observed a shorter disease-free survival of miR-9-3 methylated lung squamous cell carcinoma (LSCC) patients compared to miR-9-3 unmethylated LSCC patients by multivariate analysis (HR = 3.8, 95% CI = 1.3 to 11.2, p = 0.017) and a shorter overall survival of miR-9-3 methylated LSCC patients compared to miR-9-3 unmethylated LSCC patients by univariate analysis (p = 0.013). Conclusions: Overall, our results suggest that methylation is an important mechanism for inactivation of certain miRNAs in NSCLCs and that miR-9-3 methylation may serve as a prognostic parameter in LSCC patients.
ORGANISM(S): Homo sapiens
PROVIDER: GSE31579 | GEO | 2012/03/13
SECONDARY ACCESSION(S): PRJNA145611
REPOSITORIES: GEO
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