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Elimination of permeability mutants from selections for drug resistance in mammalian cells
Author(s) -
Schibler Matthew J.,
Barlow Steven B.,
Cabral Fernando
Publication year - 1989
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.3.2.2563346
Subject(s) - verapamil , drug , mutant , chinese hamster ovary cell , pharmacology , membrane permeability , drug resistance , vinblastine , chemistry , drug action , permeability (electromagnetism) , biology , cell culture , biochemistry , membrane , chemotherapy , gene , calcium , genetics , organic chemistry
Chinese hamster ovary (CHO) cells exhibit increased sensitivity to a wide variety of microtubule inhibitory drugs when verapamil is present in the growth medium. The extent of this increased sensitivity is drug specific: some drugs such as taxol and vinblastine respond greatly to the presence of verapamil, whereas other drugs such as griseofulvin respond very poorly. For the majority of drugs examined, however, a 2‐ to 10‐fold increase in drug sensitivity is observed in the presence of verapamil at 5 μg/ml. The effects of verapamil are even more dramatic when drug‐resistant mutant cells with a presumed alteration in membrane permeability are examined. In the presence of appropriate levels of verapamil, these mutants demonstrate a level of drug sensitivity comparable to that of the wild‐type parental cells. Drug‐resistant cells from similar selections but with well‐defined alterations in α‐ or β‐tubulin and no evidence of alterations in membrane permeability, however, continue to exhibit increased resistance to the selecting drug even in the presence of verapamil. These studies support the conclusion that verapamil affects the membrane permeability to or transport of a wide variety of hydrophobic drugs. In addition, we have used this information to devise selections that virtually eliminate the isolation of drug‐resistant permeability mutants. This methodology should be generally applicable to genetic studies of drug action that are complicated by the isolation of large numbers of mutants with permeability alterations.— S chibler , M. J.; B arlow , S. B.; C abral , F. Elimination of permeability mutants from selections for drug‐resistance in mammalian cells. FASEB J. 3: 163‐168; 1989.