The FASEB Journal, Vol 3, 163-168, Copyright © 1989 by The Federation of American Societies for Experimental Biology

RESEARCH COMMUNICATIONS

Elimination of permeability mutants from selections for drug resistance in mammalian cells

MJ Schibler, SB Barlow and F Cabral
Department of Pharmacology, University of Texas Medical School, Houston 77225.

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 micrograms/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 alpha- or beta-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.

This article has been cited by other articles:

				S. Yin, F. Cabral, and S. Veeraraghavan Amino acid substitutions at proline 220 of {beta}-tubulin confer resistance to paclitaxel and colcemid Mol. Cancer Ther., October 1, 2007; 6(10): 2798 - 2806. [Abstract] [Full Text] [PDF]

				A. Patenaude, R. G. Deschesnes, J. L.C. Rousseau, E. Petitclerc, J. Lacroix, M.-F. Cote, and R. C.-Gaudreault New Soft Alkylating Agents with Enhanced Cytotoxicity against Cancer Cells Resistant to Chemotherapeutics and Hypoxia Cancer Res., March 1, 2007; 67(5): 2306 - 2316. [Abstract] [Full Text] [PDF]

				M. Hari, F. Loganzo, T. Annable, X. Tan, S. Musto, D. B. Morilla, J. H. Nettles, J. P. Snyder, and L. M. Greenberger Paclitaxel-resistant cells have a mutation in the paclitaxel-binding region of {beta}-tubulin (Asp26Glu) and less stable microtubules. Mol. Cancer Ther., February 1, 2006; 5(2): 270 - 278. [Abstract] [Full Text] [PDF]

				M. Hari, Y. Wang, S. Veeraraghavan, and F. Cabral Mutations in {alpha}- and {beta}-Tubulin That Stabilize Microtubules and Confer Resistance to Colcemid and Vinblastine Mol. Cancer Ther., July 1, 2002; 2(7): 597 - 605. [Abstract] [Full Text] [PDF]

				S. B. Barlow, M. L. Gonzalez-Garay, and F. Cabral Paclitaxel-dependent mutants have severely reduced microtubule assembly and reduced tubulin synthesis J. Cell Sci., January 9, 2002; 115(17): 3469 - 3478. [Abstract] [Full Text] [PDF]

				J. Legault, J.-F. Gaulin, E. Mounetou, S. Bolduc, J. Lacroix, P. Poyet, and R. C.-Gaudreault Microtubule Disruption Induced in Vivo by Alkylation of {beta}-Tubulin by 1-Aryl-3- (2-Chloroethyl)Ureas, a Novel Class of Soft Alkylating Agents Cancer Res., February 1, 2000; 60(4): 985 - 992. [Abstract] [Full Text]

				M. L. Gonzalez-Garay, L. Chang, K. Blade, D. R. Menick, and F. Cabral A beta -Tubulin Leucine Cluster Involved in Microtubule Assembly and Paclitaxel Resistance J. Biol. Chem., August 20, 1999; 274(34): 23875 - 23882. [Abstract] [Full Text] [PDF]

				C. Dumontet and B. I. Sikic Mechanisms of Action of and Resistance to Antitubulin Agents: Microtubule Dynamics, Drug Transport, and Cell Death J. Clin. Oncol., March 1, 1999; 17(3): 1061 - 1061. [Abstract] [Full Text] [PDF]

				P. Giannakakou, D. L. Sackett, Y.-K. Kang, Z. Zhan, J. T. M. Buters, T. Fojo, and M. S. Poruchynsky Paclitaxel-resistant Human Ovarian Cancer Cells Have Mutant beta -Tubulins That Exhibit Impaired Paclitaxel-driven Polymerization J. Biol. Chem., July 4, 1997; 272(27): 17118 - 17125. [Abstract] [Full Text] [PDF]