Essential features of the P-glycoprotein pharmacophore as defined by a series of reserpine analogs that modulate multidrug resistance

H. L. Pearce, Ahmad Safa, N. J. Bach, M. A. Winter, M. C. Cirtain, W. T. Beck

Research output: Contribution to journalArticle

244 Citations (Scopus)

Abstract

We have shown previously that reserpine is an effective 'modulator' of P-glycoprotein-associated multidrug resistance (MDR). In addition to enhancing drug cytotoxicity in our multidrug-resistant human leukemia cell line, CEM/VLB100, reserpine strongly competes with a photoactivatible analog of vinblastine, N-(p-azido-3-[125I]iodosalicyl)-N'-(β-aminoethyl)vindesine, for binding to P-glycoprotein. We also demonstrated previously that there are three substructural domains present in many compounds that modulate P-glycoprotein-associated MDR: a basic nitrogen atom and two planar aromatic rings. In the present study, we wished to test more rigorously the hypothesis that not only are these domains necessary for modulators of MDR but also they must exist in an appropriate conformation. Reserpine is a modulator of MDR in which these domains are present in a well-defined conformation. Accordingly, we prepared eight compounds that vary the spatial orientation of these domains, using either naturally occurring reserpine or yohimbine as chemical templates. When tested for their ability to enhance the cytotoxic activity of natural product antitumor drugs in CEM/VLB100 cells, five compounds that retained the pendant benzoyl function in an appropriate spatial orientation all modulated MDR. By contrast, compounds lacking this moiety failed to do so. These active modulators competed strongly with the 125I-labeled vinblastine analog for binding to P-glycoprotein in plasma membrane vesicles prepared from these cells. Conformational analysis using molecular mechanics revealed the structural similarities of the active modulators. Our results support the hypothesis that the relative disposition of aromatic rings and basic nitrogen atom is important for modulators of P-glycoprotein-associated MDR, and they suggest a ligand-receptor relationship for these agents. These results also provide direction for the definition of an MDR 'pharmacophore'.

Original languageEnglish (US)
Pages (from-to)5128-5132
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume86
Issue number13
StatePublished - 1989
Externally publishedYes

Fingerprint

Reserpine
Multiple Drug Resistance
P-Glycoprotein
Vinblastine
Nitrogen
Vindesine
Yohimbine
Biological Products
Mechanics
Antineoplastic Agents
Leukemia
Cell Membrane
Ligands
Cell Line
Pharmaceutical Preparations

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

Essential features of the P-glycoprotein pharmacophore as defined by a series of reserpine analogs that modulate multidrug resistance. / Pearce, H. L.; Safa, Ahmad; Bach, N. J.; Winter, M. A.; Cirtain, M. C.; Beck, W. T.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 86, No. 13, 1989, p. 5128-5132.

Research output: Contribution to journalArticle

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