Mutations leading to antifolate resistance in Chinese hamster ovary cells after exposure to the alkylating agent ethylmethanesulfonate Journal Article

  

Authors:	Fanin, R.; Banerjee, D.; Volkenandt, M.; Waltham, M.; Li, W. W.; Dicker, A. P.; Schweitzer, B. I.; Bertino, J. R.
Article Title:	Mutations leading to antifolate resistance in Chinese hamster ovary cells after exposure to the alkylating agent ethylmethanesulfonate
Abstract:	Chinese hamster ovary cells with a single allele for dihydrofolate reductase were used as a model system to study the effect of exposure to an alkylating agent, ethylmethanesulfonate, on rates and types of mutations at the dihydrofolate reductase locus leading to antifolate resistance. After overnight exposure to 400 μg/ml ethylmethanesulfonate, cells were allowed to recover for 3 days, and resistant colonies were selected in 8 x 10-8 M trimetrexate. Trimetrexate, rather than methotrexate, was used as the selecting agent to increase the probability of obtaining mutations in dihydrofolate reductase, rather than in the reduced folate transport carrier protein. Seven of several hundred surviving colonies were selected at random, and cell lines were established. Cell lines 1-3 were maintained in culture in the presence of 8 x 10-8 M trimetrexate and were 66-170-fold resistant to the drug. Cell lines 4-7 were initially expanded in 8 x 10-8 M trimetrexate but were then maintained in the absence of the drug. These cell lines were 4.4-26-fold resistant to the drug, compared with the parental cell line. Cell line 1 was found to have an increase in dihydrofolate reductase activity, a corresponding increase in mRNA for dihydrofolate reductase, and amplification of this gene. Cell lines 2 and 6 had a mutated dihydrofolate reductase with altered trimetrexate- and methotrexate-binding properties. Cell line 3 had a 3-fold increase in dihydrofolate reductase activity. In cell lines 4, 5, and 7 the mechanisms of resistance to trimetrexate remain unknown.
Keywords:	carrier protein; mutation; doxorubicin; nonhuman; methotrexate; animal cell; animal; gene amplification; cell line; gene locus; drug resistance; enzyme activity; vinblastine; molecular sequence data; cell culture; base sequence; folic acid; alkylating agents; dihydrofolate reductase; folic acid antagonists; tetrahydrofolate dehydrogenase; blotting, northern; ligand binding; drug interactions; cho cell; cho cells; trimetrexate; chemical mutagenesis; blotting, southern; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; hamsters; mesylic acid ethyl ester; ethyl methanesulfonate
Journal Title:	Molecular Pharmacology
Volume:	44
Issue:	1
ISSN:	0026-895X
Publisher:	The American Society for Pharmacology and Experimental Therapeutics
Date Published:	1993-07-01
Start Page:	13
End Page:	21
Language:	English
PUBMED:	8341268
PROVIDER:	scopus
DOI/URL:	https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027240205&partnerID=40&md5=e1bc30175e91e04823401e6b9c700e8f
Notes:	Article -- Export Date: 1 March 2019 -- Source: Scopus

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