Related Experiment Videos
Indoloquinoxaline compounds that selectively antagonize P-glycoprotein.
C D Smith1, C B Myers, J T Zilfou
1Department of Pharmacology, Pennsylvania State University, Hershey 17033, USA. cdsmith@psu.edu
Oncology Research
|June 22, 2001
Summary
New indoloquinoxaline compounds selectively reverse P-glycoprotein (Pgp)-mediated multidrug resistance (MDR) in cancer cells. These novel agents enhance anticancer drug efficacy without affecting MRP1-overexpressing or normal cells, showing promise as MDR modulators.
Area of Science:
- Molecular Pharmacology
- Medicinal Chemistry
- Cancer Biology
Background:
- Tumor cells frequently develop drug resistance via overexpression of membrane transport proteins, such as P-glycoprotein (Pgp) and MRP1, which efflux anticancer agents.
- Understanding the distinct pharmacologies of Pgp and MRP1 is crucial for developing effective drug resistance reversing agents.
- Selective targeting of these transporters can improve the therapeutic potential of chemotherapy.
Purpose of the Study:
- To identify novel compounds with selective activity against Pgp or MRP1.
- To synthesize and evaluate indoloquinoxaline derivatives for their ability to reverse multidrug resistance (MDR).
- To assess the selectivity of these compounds in modulating transporter-mediated drug resistance.
Main Methods:
- Screening of a commercial compound library to identify transporter-selective agents.
- Chemical synthesis of selected indoloquinoxaline derivatives, including 1,4-dibutoxy-6H-indolo[2,3-b]quinoxaline and 4,7-dibutoxy-2,3-dihydrobenzimidazole-2-spiro-3-indolin-2-one.
- In vitro evaluation of compound cytotoxicity, drug sensitivity modulation in various cancer cell lines (MCF-7, NCI/ADR, HL-60/ADR), and intracellular drug accumulation assays.
Main Results:
- Synthesized indoloquinoxaline compounds demonstrated selective sensitization of Pgp-overexpressing cells (NCI/ADR) to multiple anticancer drugs (vinblastine, actinomycin D, Taxol, doxorubicin) at low micromolar concentrations.
- These compounds did not affect the sensitivity of MRP1-overexpressing cells (MCF-7/VP, HL-60/ADR) or non-transporter-overexpressing cells (MCF-7, T24) to these drugs, nor did they affect sensitivity to cisplatin or 5-fluorouracil.
- The compounds enhanced intracellular accumulation of vinblastine in Pgp-overexpressing cells but did not inhibit Pgp photoaffinity labeling, suggesting a mechanism distinct from direct Pgp inhibition.
Conclusions:
- Novel, non-toxic indoloquinoxaline derivatives selectively reverse Pgp-mediated multidrug resistance (MDR).
- These compounds exhibit transporter selectivity, modulating Pgp but not MRP1 or other drug sensitivities.
- The selective nature of these indoloquinoxalines suggests significant potential as effective in vivo MDR modulators in cancer therapy.