Increased O6-alkylguanine alkyltransferase activity in Chinese hamster V79 cells following selection with chloroethylating agents.
AffiliationPaterson Institute for Cancer Research, Christie Hospital and Holt Radium Institute, Manchester, UK.
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AbstractChinese hamster V79 lung fibroblasts express low levels (specific activity 2-4 fmol/mg protein) of O6-alkylguanine (O6-AG) alkyltransferase (ATase). In cells surviving selection with low doses (10 micrograms/ml) of the chloroethylating agent, mitozolomide (Mz), ATase activity was increased 5- to 8-fold. Repeated selection of such cells produced a maximal specific activity of 36-40 fmol/mg protein, whilst selection at 20 or 40 micrograms/ml result in specific activities of approximately 50 and 70 fmol/mg respectively. Only slight decreases in ATase activity were seen by 51 days after an initial selection with 10 micrograms/ml Mz. A similar effect was observed using chlorozotocin. Selected cells had a higher D37 for Mz (2.5-6.0 micrograms/ml) in comparison with control cell (D37, 0.8 micrograms/ml) but the D37s for nitrogen mustard and vincristine were closely similar in selected and control cells. Possible explanations for the increase in ATase activity are discussed.
CitationIncreased O6-alkylguanine alkyltransferase activity in Chinese hamster V79 cells following selection with chloroethylating agents. 1988, 9 (1):45-9 Carcinogenesis