Interaction of structurally diverse pesticides with the human MDR1 gene product P-glycoprotein

Toxicol Appl Pharmacol. 1996 Nov;141(1):288-98. doi: 10.1006/taap.1996.0286.


P-glycoprotein (P-gp) is a 170-kDa membrane-bound glycoprotein shown to efflux a wide variety of chemicals, such as chemotherapeutic agents and carcinogens. Experiments were conducted using B16/F10 murine melanoma cells transfected with the human MDR1 gene (B16/hMDR1 cells), which codes for P-gp, to determine whether this transporter may contribute to the cellular efflux of some pesticides. Thirty-eight pesticides representing several classes of compounds were evaluated for their potential to bind to P-gp, as measured by the inhibition of efflux of the P-gp substrate doxorubicin. Carbamate and pyrethroid insecticides exhibited little interaction with P-gp, while many of the organophosphorus and organochlorine pesticides significantly inhibited the efflux of doxorubicin. Pesticides that significantly inhibited the efflux of doxorubicin were then assessed for P-gp-mediated efflux. One pesticide, endosulfan, exhibited slight though significant transport mediated by P-gp. Competition experiments performed with the P-glycoprotein ligand [3H]azidopine demonstrated that the P-gp inhibitory pesticides bound to P-gp. Both lipophilicity and molecular mass were major physical/chemical determinants in dictating pesticide binding to P-gp, with optimum binding occurring with compounds having a log Kow value of 3.6-4.5 and a molecular weight of 391-490 Da. The transport substrate endosulfan possessed optimal binding characteristics. These results demonstrated that many pesticides are capable of binding to P-gp; however, binding does not infer transport.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / antagonists & inhibitors*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / physiology
  • Animals
  • Cell Membrane / drug effects
  • Doxorubicin / metabolism
  • Genes, MDR / drug effects*
  • Humans
  • Melanoma, Experimental / genetics*
  • Melanoma, Experimental / metabolism
  • Mice
  • Pesticides / metabolism*
  • Pesticides / toxicity*
  • Structure-Activity Relationship
  • Tumor Cells, Cultured


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Pesticides
  • Doxorubicin