Wide methylation analysis in vestibular schwannoma [Affymetrix exon level analysis]

Vestibular schwannomas are intracranial tumors that affects unilateral and sporadically or bilateral when is associated to Neurofibromatosis type 2 syndrome. The hallmark of the disease is the biallelic inactivation by NF2 gene mutation or LOH of chromosome 22q, where this gene harbors. In this work, we used Infinium HumanMethylation 450K BeadChip microarrays in a series of 36 vestibular schwannomas, 4 non-vestibular schwannomas and 5 healthy nerves. Our results shows a trend to hypomethylation in schwannomas. Furthermore, HOX genes, located at 4 clusters in the genome, displayed hypomethylation in numerous CpG sites in vestibular but not in non-vestibular schwannomas. Additionally, several microRNA and protein-coding genes were found hypomethylated at promoter regions and confirmed by expression analysis; including miRNA-199a1, miRNA-21, MET and PMEPA1. We also detected methylation patterns that might be involved in alternative transcripts of several genes such as NRXN1 or MBP; that would increase the complexity of methylation-expression. Overall, our results shows specific epigenetic signatures in several coding genes and microRNA that could be used in the finding of potential therapeutic targets. Microarrays of vestibular and 4 non-vestibular schwannomas were used in Affymetrix Human Gene 1.0 ST, at exon level. Batch correction was performed between tumors and controls to avoid batch effect.