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Biochem Biophys Res Commun. 1999 Dec 9;266(1):167-73.

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

Author information

1
The Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey/Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA. jyang@rwja.umdnj.edu

Abstract

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.

PMID:
10581184
DOI:
10.1006/bbrc.1999.1757
[Indexed for MEDLINE]

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