Expression of the genes of methyl-binding domain proteins in human gliomas.

DNA methylation is the most common epigenetic alteration in tumor genomes and might result in transcriptional repression of tumor suppressor genes. Moreover, recent results have demonstrated that both specific methylation patterns and functional components of the mismatch repair system are involved in the development of therapy resistance of tumor cells. Here we investigated the expression of the genes of methyl binding domain containing proteins (MBD) in human gliomas both in vivo and in vitro. We found expression of MBDs including MBD1, MBD2, MBD3 and MBD4/MED1 in all glioma cell lines and glioma biopsies. No differences existed in vitro with regard to individual MBDs and individual cell lines. In vivo, MBD1 and MBD2 were also expressed in all biopsies with only minor differences between individual tumors. MBD3 and MBD4/MED1, however, showed a correlation of expression with the grade of malignancy. Astrocytomas and anaplastic astrocytomas showed a weak expression compared with a high expression in glioblastoma multiforme.