gms | German Medical Science

65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

11. - 14. Mai 2014, Dresden

The epigenetic route of temozolomide action in brain tumor cells

Meeting Abstract

  • Anna-Maria Barciszewska - Department of Neurosurgery and Neurotraumatology, Karol Marcinkowski University of Medical Sciences, Poznan, Poland
  • Stanislaw Nowak - Department of Neurosurgery and Neurotraumatology, Karol Marcinkowski University of Medical Sciences, Poznan, Poland
  • Eliza Wyszko - Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Poznan, Poland
  • Monika Piwecka - Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Poznan, Poland
  • Miroslawa Z. Barciszewska - Institute of Bioorganic Chemistry of the Polish Academy of Sciences, Poznan, Poland

Deutsche Gesellschaft für Neurochirurgie. 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Dresden, 11.-14.05.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocP 055

doi: 10.3205/14dgnc439, urn:nbn:de:0183-14dgnc4390

Veröffentlicht: 13. Mai 2014

© 2014 Barciszewska et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: Malignant gliomas are aggressive neoplasms with a dismal prognosis despite optimal treatment, i.e. surgery combined with radiotherapy. Systemic chemotherapy is less effective. However, temozolomide (TMZ) has been shown to increase overall survival in glioblastoma patients. Its active metabolite methylates DNA bases in several positions, N7G, N3A and O6G, the last one regarded as the lethal lesion. We’ve investigated the TMZ effects on the amount of DNA epigenetic marker, 5-methylcytosine (m5C). The aim of our study was to evaluate the molecular mechanism of temozolomide action, the drug of choice in glioma treatment.

Method: We've treated C6, glioblastoma and HeLa cell lines with TMZ dissolved in DMSO at different time. DANN from cultured cells was isolated, hydrolysed into nucleotides, labelled with 32P-ATP and separated with two dimensional thin layer chromatography. Chromatograms were evaluated using phosphoimager and the amounts of m5C calculated as a spot intensities ratio of m5C to m5C+C+T.

Results: We've shown that TMZ treatment affects m5C formation in DNA. m5C amount in glioma DANN increased significantly after short treatment with TMZ, whereas longer treatment caused demethylation.

Conclusions: TMZ modifies epigenetic pattern through changing the 5-methylcytosine level in DNA. We showed that in addition to guanine and adenine methylation, TMZ induces methylation of cytosine at short times, then causing DNA demethylation. The first effect is due to transiently activated DNA methyltransferases and the second due to reactive oxygen species induced m5C damage. The observed final global hypomethylation of the genome contributes to epigenetic gene expression regulation.