BACKGROUND: Glioblastoma is the commonest malignant brain tumor and has a very poor prognosis. Reduced expression of the MGMT gene (10q26.3), influenced primarily by the methylation of two differentially methylated regions (DMR1 and DMR2), is associated with a good response to temozolomide treatment. However, suitable methods for detecting the methylation of the MGMT gene promoter and setting appropriate cutoff values are debated. RESULTS: A cohort of 108 patients with histologically and genetically defined glioblastoma was retrospectively examined with methylation-specific Sanger sequencing (sSeq) and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) methods. The DMR2 region was methylated in 29% of samples, whereas DMR1 was methylated in 12% of samples. Methylation detected with the MS-MLPA method using probes MGMT_215, MGMT_190, and MGMT_124 from the ME012-A1 kit (located in DMR1 and DMR2) correlated with the methylation of the corresponding CpG dinucleotides detected with sSeq (p = 0.005 for probe MGMT_215; p < 0.001 for probe MGMT_190; p = 0.016 for probe MGMT_124). The threshold for methylation detection with the MS-MLPA method was calculated with a ROC curve analysis and principal components analysis of the data obtained with the MS-MLPA and sSeq methods, yielding a weighted value of 0.362. Thus, methylation of the MGMT gene promoter was confirmed in 36% of samples. These patients had statistically significantly better overall survival (p = 0.003). CONCLUSIONS: Our results show that the threshold for methylation detection with the MS-MLPA method determined here is useful from a diagnostic perspective because it allows the stratification of patients who will benefit from specific treatment protocols, including temozolomide. Detailed analysis of the MGMT gene promoter enables the more-precise and personalized treatment of patients with glioblastoma.

• Klíčová slova
• MGMT, Glioblastoma, MS-MLPA, Methylation, Sanger sequencing, Stupp protocol,
• MeSH
• DNA modifikační methylasy genetika   MeSH
• dospělí MeSH
• enzymy opravy DNA * genetika   MeSH
• glioblastom * genetika   farmakoterapie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• metylace DNA * MeSH
• multiplexová polymerázová řetězová reakce * metody   MeSH
• nádorové supresorové proteiny genetika   MeSH
• nádory mozku * genetika   farmakoterapie   MeSH
• promotorové oblasti (genetika) MeSH
• retrospektivní studie MeSH
• sekvenční analýza DNA * metody   MeSH
• senioři MeSH
• temozolomid MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• validační studie MeSH
• Názvy látek
• DNA modifikační methylasy MeSH
• enzymy opravy DNA * MeSH
• MGMT protein, human MeSH Prohlížeč
• nádorové supresorové proteiny MeSH
• temozolomid MeSH

DNA methylation, i.e., addition of methyl group to 5'-carbon of cytosine residues in CpG dinucleotides, is an important epigenetic modification regulating gene expression, and thus implied in many cellular processes. Deregulation of DNA methylation is strongly associated with onset of various diseases, including cancer. Here, we review how DNA methylation affects carcinogenesis process and give examples of solid tumors where aberrant DNA methylation is often present. We explain principles of methods developed for DNA methylation analysis at both single gene and whole genome level, based on (i) sodium bisulfite conversion, (ii) methylation-sensitive restriction enzymes, and (iii) interactions of 5-methylcytosine (5mC) with methyl-binding proteins or antibodies against 5mC. In addition to standard methods, we describe recent advances in next generation sequencing technologies applied to DNA methylation analysis, as well as in development of biosensors that represent their cheaper and faster alternatives. Most importantly, we highlight not only advantages, but also disadvantages and challenges of each method.

• Klíčová slova
• DNA biosensor, DNA methylation, bisulfite conversion, epigenetic modification, restriction enzyme, tumor, tumorigenesis,
• MeSH
• 5-methylcytosin metabolismus   MeSH
• biosenzitivní techniky metody   MeSH
• epigeneze genetická genetika   MeSH
• lidé MeSH
• metylace DNA genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• 5-methylcytosin MeSH

Colorectal carcinogenesis (CRC) is caused by the gradual long-term accumulation of both genetic and epigenetic changes. Recently, epigenetic alterations have been included in the classification of the CRC molecular subtype, and this points out their prognostic impact. As epigenetic modifications are reversible, they may represent relevant therapeutic targets. DNA methylation, catalyzed by DNA methyltransferases (DNMTs), regulates gene expression. For many years, the deregulation of DNA methylation has been considered to play a substantial part in CRC etiology and evolution. Despite considerable advances in CRC treatment, patient therapy response persists as limited, and their profit from systemic therapies are often hampered by the introduction of chemoresistance. In addition, inter-individual changes in therapy response in CRC patients can arise from their specific (epi)genetic compositions. In this review article, we summarize the options of CRC treatment based on DNA methylation status for their predictive value. This review also includes the therapy outcomes based on the patient's methylation status in CRC patients. In addition, the current challenge of research is to develop therapeutic inhibitors of DNMT. Based on the essential role of DNA methylation in CRC development, the application of DNMT inhibitors was recently proposed for the treatment of CRC patients, especially in patients with DNA hypermethylation.

• Klíčová slova
• DNMT inhibitors, colorectal cancer, methylation, therapy,
• MeSH
• kolorektální nádory genetika   terapie   MeSH
• lidé MeSH
• metylace DNA genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Specific gene mutations, loss of heterozygosity, deletions and/or amplifications of entire chromosomal regions and gene silencing have been described in gliomas. 82 samples from 81 patients were investigated to detect the deletion of TP53, RB1, CDKN2A genes, deletion of 1p36 and 19q13.3 region, amplification of EGFR gene, trisomy of chromosome 7 and monosomy of chromosome 10 in glial cells. Dual-colour interphase fluorescence in situ hybridization (I-FISH) with locus-specific and/or chromosome enumeration DNA probes were used for cytogenetic analyses. In the study, molecular cytogenetic analyses were successfully performed in 74 patients (91.3%) and were uninformative in 7 only (8.7%). The cytogenetic analyses were correlated with morphological data and clinical outcome. I-FISH was the essential part of diagnostics. In comparison with the clinical data, the patients' age seems to be a factor more important for the overall survival, rather than cytogenetic findings in glial tumours. The combined deletion of 1p36 and 19q13.3 chromosomal regions predicts longer overall survival for patients with oligodendroglial tumours.

• MeSH
• cytogenetické vyšetření MeSH
• dospělí MeSH
• gliom genetika   mortalita   patologie   MeSH
• hybridizace in situ fluorescenční MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• nádory mozku genetika   mortalita   patologie   MeSH
• prognóza MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH