Attenuation of O6-methylguanine-DNA methyltransferase activity and mRNA levels by cisplatin and temozolomide in Jurkat cells

Stefania D'Atri, Grazia Graziani, Pedro Miguel Lacal, Vittoria Nisticò, Sara Gilberti, Isabella Faraoni, Amanda J. Watson, Enzo Bonmassar, Geoffrey P. Margison

Research output: Contribution to journalArticle

Abstract

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) is important in cellular resistance to certain alkylating antitumor agents such as the methylating drug temozolomide (TMZ). To provide a more rational basis for clinical combinations with another commonly used drug, cisplatin, we assessed the modulation of MGMT protein and mRNA levels in the human leukemic cell line Jurkat after treatment with these agents. Cisplatin decreased MGMT activity in a time- and dose-dependent manner, with maximal suppression (50%) observed 24 h after treatment with 25 μM cisplatin. This was probably the result of decreased transcription of the MGMT gene, because there was an earlier nadir of MGMT mRNA levels after cisplatin treatment and neither cisplatin nor DNA reacted with cisplatin in vitro was able to inhibit MGMT activity in an in vitro assay. TMZ alone depleted MGMT activity in a time- and dose-dependent manner with almost complete loss of activity occurring immediately after treatment with 500 μM TMZ. Combinations of cisplatin (12.5 μM) and TMZ (250 μM) caused substantial and prolonged MGMT depletion with recovery to only 30% of pretreatment levels by 48 h. These results suggest that the clinical efficacy of TMZ and cisplatin may be improved by appropriate schedules of combinations of these agents.

Original languageEnglish
Pages (from-to)664-671
Number of pages8
JournalJournal of Pharmacology and Experimental Therapeutics
Volume294
Issue number2
Publication statusPublished - Aug 2000

ASJC Scopus subject areas

  • Pharmacology

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    D'Atri, S., Graziani, G., Lacal, P. M., Nisticò, V., Gilberti, S., Faraoni, I., Watson, A. J., Bonmassar, E., & Margison, G. P. (2000). Attenuation of O6-methylguanine-DNA methyltransferase activity and mRNA levels by cisplatin and temozolomide in Jurkat cells. Journal of Pharmacology and Experimental Therapeutics, 294(2), 664-671.