Histone code and epigenetic regulation of PTEN gene in malignant gliomas

To analyse the transcriptional activity of PTEN in 7 primary cultures of gliomas we have used two epigenetic markers of histone H3 posttranlational modifications: H3K9me3 and H3K4ac, which are typical for active and repressed chromatin, respectively. The presence of suppression marker of transcriptional activity (H3K9me3) near the transcriptional initiation site (exon I) was found in 6 of 7 cell lines investigated, and only one line shown to contain the acetylated H3K4ac form in this region of PTEN. Additional analysis of histone signature in exon 5 region of the gene has revealed the only H3K9me3 marker in all 7 cell cultures. The data obtained indicate the suppression of transcriptional activity of PTEN in most analysed gliomas through altered histone code, which seems to be an universal mechanism of epigenetic regulation of PTEN expression in gliomas.