Treatment of multidrug resistant (MDR1) murine leukemia with P-glycoprotein substrates accelerates the course of the disease

Biochem Biophys Res Commun. 1999 Dec 9;266(1):167-73. doi: 10.1006/bbrc.1999.1757.


The prognosis of patients with tumors expressing P-glycoprotein (P-gp), the MDR1 gene product, is generally poor. It is assumed that this is due to decreased tumor responsiveness that results from decreased drug accumulation. We observed that treatment of animals bearing MDR1-transfected leukemic cells with P-gp substrates (i.e., drugs that are transported by P-gp) significantly worsened host survival compared to treatment with vehicle or non-P-gp substrates. This effect was seen with cancer chemotherapeutic agents (paclitaxel and vincristine) and with the MDR modulator, trans-flupenthixol. To determine the mechanism(s) underlying this observation, we studied alterations in pharmacokinetics, pharmacodynamics, and metastasis. We found that the drug-induced acceleration of disease was associated with increased metastases. P-gp(+) cells treated with P-gp substrates demonstrated several pro-metastatic features, including membrane ruffling and invasion through a hepatocyte monolayer. These results suggest that the treatment of MDR tumors with P-gp substrates may produce changes in malignant behavior that could adversely affect therapeutic outcomes.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Animals
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cell Movement / drug effects
  • Disease Progression
  • Drug Resistance, Neoplasm*
  • Female
  • Flupenthixol / pharmacology
  • Humans
  • Hydrogen-Ion Concentration
  • Leukemia P388 / metabolism
  • Leukemia P388 / pathology*
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology
  • Liver Neoplasms / secondary
  • Mechlorethamine / pharmacology
  • Mice
  • Neoplasm Invasiveness
  • Neoplasm Transplantation
  • Paclitaxel / pharmacokinetics
  • Paclitaxel / pharmacology
  • Survival Rate
  • Tumor Cells, Cultured
  • Vincristine / pharmacokinetics
  • Vincristine / pharmacology


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Mechlorethamine
  • Vincristine
  • Flupenthixol
  • Paclitaxel