Schisandrol A from Schisandra chinensis reverses P-glycoprotein-mediated multidrug resistance by affecting Pgp-substrate complexes

David W F FONG*, Chi Keung Wan, Cuo Yuan Zhu, Apurba Chattopadhyay, Saibal Dey, Zhongzhen ZHAO, Xiao Ling Shen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

Recent studies have shown that dibenzocyclooctadiene lignans may reverse P-glycoprotein-mediated multidrug resistance (Pgp-MDR) in cancer cells; however, the mechanism of action remains unknown. Through screening of herbs, we found that schisandrol A (SCH) isolated from Fructus Schisandrae (the dried fruit of Schisandra chinensis (Turcz.) Baill.) sensitized Pgp-MDR HepG2-DR cells by interfering with the function of Pgp-substrate complexes. In Pgp-MDR cells, SCH enhanced the cytotoxicity of cancer drugs that are Pgp substrates and restored vinblastine-induced G2/M arrest without lowering Pgp expression. SCH increased cellular retention of Pgp substrates such as rhodamine 123. In Pgp-overexpressing membrane preparations, SCH stimulated basal Pgp-ATPase thus showing some substrate-like function. However, SCH was not a competitive inhibitor for verapamil or progesterone and decreased their Km. In the presence of substrates, SCH decreased the reactivity between Pgp and the monoclonal antibody UIC-2 which is normally increased with active substrate-Pgp complexes. The labeling of active Pgp transport sites by [125I]- iodoarylazidoprazosin was partially blocked by SCH. SCH did not affect the activity of the mutant Pgp F983A suggesting that SCH acted differently than the thioxanthene type of Pgp allosteric inhibitors. Our results suggest that SCH acts by affecting the normal formation and functioning of the Pgp-substrate complexes.

Original languageEnglish
Pages (from-to)212-220
Number of pages9
JournalPlanta Medica
Volume73
Issue number3
DOIs
Publication statusPublished - Mar 2007

Scopus Subject Areas

  • Analytical Chemistry
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Drug Discovery
  • Complementary and alternative medicine
  • Organic Chemistry

User-Defined Keywords

  • Lignan
  • Multidrug resistance
  • P-glycoprotein
  • Schisandra chinensis
  • Schisandraceae
  • Schisandrol A
  • Substrate interaction

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