Abstract |
The O6-methylguanine-DNA-methyltransferase activity was measured in rat hepatoma cells (H4 cells) at different times after N-methyl-N'-nitro-N-nitrosoguanidine ( MNNG), methylmethane sulfonate (MMS) or ethylmethane sulfonate (EMS) treatment. Incubation with MNNG (10 microM) first depletes the methyltransferase activity, then the number of methyltransferase molecules per cell increases and reaches approximately 3-fold the constitutive level after 48 h. Incubations with MMS (0.5 or 1 mM) or with EMS (5 or 10 mM) do not modify or partially decrease the constitutive methyltransferase level. However, an enhancement of the activity is also observed after 48 h: the activity in 5- and 4-fold higher than the control value in MMS- and EMS-treated cells, respectively. The methyltransferase increase is due to de novo protein synthesis. It is not observed in cells constitutively lacking this protein. The data suggest that the O6-methylguanine (O6-meGua) repair capacity of H4 cells can be increased after a single treatment with alkylating agents, by a process different to the adaptive response.
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Authors | G Frosina, F Laval |
Journal | Carcinogenesis
(Carcinogenesis)
Vol. 8
Issue 1
Pg. 91-5
(Jan 1987)
ISSN: 0143-3334 [Print] England |
PMID | 3802398
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Alkylating Agents
- Methylnitronitrosoguanidine
- Ethyl Methanesulfonate
- Methyl Methanesulfonate
- Methyltransferases
- O(6)-Methylguanine-DNA Methyltransferase
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Topics |
- Alkylating Agents
(pharmacology)
- Animals
- Cell Line
- Ethyl Methanesulfonate
(pharmacology)
- Liver Neoplasms, Experimental
(enzymology)
- Methyl Methanesulfonate
(pharmacology)
- Methylnitronitrosoguanidine
(pharmacology)
- Methyltransferases
(metabolism)
- O(6)-Methylguanine-DNA Methyltransferase
- Rats
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