title: A New Epigenetic Mechanism of Temozolomide Action in Glioma Cells.
abstract: Temozolomide (TMZ) is an oral alkylating chemotherapeutic agent that prolongs the survival of patients with glioblastoma (GBM). Despite that high TMZ potential, progression of disease and recurrence are still observed. Therefore a better understanding of the mechanism of action of this drug is necessary and may allow more durable benefit from its anti-glioma properties. Using nucleotide post-labelling method and separation on thin-layer chromatography we measured of global changes of 5-methylcytosine (m5C) in DNA of glioma cells treated with TMZ. Although m5C is not a product of TMZ methylation reaction of DNA, we analysed the effects of the drug action on different glioma cell lines through global changes at the level of the DNA main epigenetic mark. The first effect of TMZ action we observed is DNA hypermethylation followed by global demethylation. Therefore an increase of DNA methylation and down regulation of some genes expression can be ascribed to activation of DNA methyltransferases (DNMTs). On the other hand hypomethylation is induced by oxidative stress and causes uncontrolled expression of pathologic protein genes. The results of brain tumours treatment with TMZ suggest the new mechanism of modulation epigenetic marker in cancer cells. A high TMZ concentration induced a significant increase of m5C content in DNA in the short time, but a low TMZ concentration at longer time hypomethylation is observed for whole range of TMZ concentrations. Therefore TMZ administration with low doses of the drug and short time should be considered as optimal therapy.
authors: Department of Neurosurgery and Neurotraumatology, Karol Marcinkowski University of Medical Sciences, Przybyszewskiego 49, 60-355, Poznan, Poland.
authors: Anna-Maria
authors: AM
authors: Barciszewska
authors: Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Noskowskiego 12, 61-704, Poznan, Poland.
authors: Dorota
authors: D
authors: Gurda
authors: Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Noskowskiego 12, 61-704, Poznan, Poland.
authors: Paweł
authors: P
authors: Głodowicz
authors: Department of Neurosurgery and Neurotraumatology, Karol Marcinkowski University of Medical Sciences, Przybyszewskiego 49, 60-355, Poznan, Poland.
authors: Stanisław
authors: S
authors: Nowak
authors: Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Noskowskiego 12, 61-704, Poznan, Poland.
authors: Mirosława Z
authors: MZ
authors: Naskręt-Barciszewska
mesh_terms: D044503:5-Methylcytosine / Q000737:chemistry; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000235:genetics; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry; D019175:DNA Methylation / Q000187:drug effects*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D044127:Epigenesis, Genetic; D005910:Glioma / Q000188:drug therapy* / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D000077204:Temozolomide
chemical_list: D018906:Antineoplastic Agents, Alkylating; D044503:5-Methylcytosine; D003606:Dacarbazine; D004247:DNA; D000077204:Temozolomide