P152

In this study, we asked by using gastrointestinal stromal tumours as a model if an epigenetic related HOX Antisense Intergenic RNA, or HOTAIR, is involved in establishment of DNA methylation patterns. To this end, we first showed high up-regulation of HOTAIR in patient samples of high risk compared to low and intermediate risk groups (n =66, p =6.7×10−6), what is supported by the earlier reports on common carcinomas. Highest levels of HOTAIR endogenous expression were next detected also in cell lines GIST T1, GIST48b and GIST882. Stable knockdown of HOTAIR was achieved in GIST T1 and GIST48b cells by RNAi using lentiviral transduction. As expected epigenetic alterations due to HOTAIR knockdown could develop with a delay, genome-wide DNA methylation profiling was performed at passage 12 after the transduction on the Infinium HumanMethylation450 BeadChip platform in triplicates. DNA methylation data were analysed by an R package RnBeads. A total of 218 CpG sites got hypomethylated upon HOTAIR knockdown in GIST T1 and GIST48b cells (Δβ >0.3, FDR<0.05). These included potential tumour suppressors, transcription factors, tumour-specific antigens, genes related to angiogenesis or involved in metabolism. As confirmed by using bisulfite pyrosequencing for a representative locus, DNA methylation of 64% degree at promoter associated CpG sites of the potential tumour suppressor RASSF1 was almost entirely erased upon HOTAIR knockdown in GIST T1 cell line with concomita...
Source: European Journal of Cancer Supplements - Category: Cancer & Oncology Source Type: research