Selective Inhibition of P-glycoprotein Expression in Multidrug-Resistant Tumor Cells by a Designed Transcriptional Regulator (original) (raw)
Research ArticleCELLULAR AND MOLECULAR
Journal of Pharmacology and Experimental Therapeutics September 2002, 302 (3) 963-971; DOI: https://doi.org/10.1124/jpet.102.033639
Abstract
Selective inhibition of the multidrug resistance 1 (MDR1) gene and its product, the P-glycoprotein, a membrane transporter responsible for multidrug resistance, could be an important approach for enhancing cancer therapeutics. An emerging strategy for selective gene regulation involves designed zinc finger proteins that can recognize specific sequences in the promoter regions of disease-related genes. Herein, we investigate the behavior of clones of multidrug-resistant NCI/ADR-RES breast carcinoma cells displaying ponasterone-inducible expression of a designed transcriptional repressor targeted to the MDR1 promoter. The controlled production of this novel repressor resulted in major reductions in P-glycoprotein levels in these otherwise highly drug-resistant tumor cells. The regulated reduction of MDR1 expression in NCI/ADR-RES cells was accompanied by a marked increase in the rate of uptake of the P-glycoprotein substrate rhodamine 123. In addition, the cytotoxicity profile of the antitumor drug doxorubicin was dramatically altered in the induced cells compared with controls. The expression levels of other genes were examined both by a DNA array analysis of approximately 2000 genes and by biochemical techniques. Although some changes were observed in mRNA levels of nontargeted genes, the most dramatic effect by far was on MDR1, indicating that the action of the designed transcriptional repressor was quite selective. This study suggests that designed transcriptional regulators can be used to strongly and selectively influence expression of cancer-related genes, even under circumstances of extensive amplification of the target gene.
Footnotes
This work was supported by National Institutes of Health Grants RO1 CA77340 and PO1 GM 59299 (to R.L.J.).
DOI: 10.1124/jpet.102.033639
Abbreviations:
MDR
multidrug resistance
Zif
zinc finger
Rh123
rhodamine 123
PBS
phosphate-buffered saline
R-PE
_R_-phycoerythrin
MHC
major histocompatibility complex- Received January 29, 2002.
- Accepted April 5, 2002.
The American Society for Pharmacology and Experimental Therapeutics
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