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Reversal effects of Ca2+ antagonists on multidrug resistance via down-regulation of MDR1 mRNA

Chiho Komoto1, Tsutomu Nakamura, Motohiro Yamamori

  • 1Department of Hospital Pharmacy, School of Medicine, Kobe University, Kobe 650-0017, Japan.

The Kobe Journal of Medical Sciences
|September 3, 2008
PubMed

Insights

Calcium channel blockers can reverse multidrug resistance by down-regulating P-glycoprotein/MDR1. This study confirms their efficacy and suggests a novel mechanism involving MDR1 mRNA down-regulation for overcoming cancer drug resistance.

Area of Science:

  • Pharmacology
  • Molecular Biology
  • Oncology

Background:

  • Multidrug resistance (MDR) is a major challenge in cancer chemotherapy.
  • P-glycoprotein (P-gp/MDR1) is a key transporter protein responsible for MDR.
  • Calcium (Ca2+) antagonists have shown potential in modulating P-gp activity.

Purpose of the Study:

  • To confirm the effects of 12 Ca2+ antagonists on MDR1-mediated drug transport and cellular sensitivity.
  • To investigate the underlying molecular mechanisms of Ca2+ antagonist-induced reversal of MDR.
  • To explore novel strategies for overcoming MDR in cancer treatment.

Main Methods:

  • Evaluation of Ca2+ antagonists' effects on [3H]digoxin transport mediated by P-gp.
  • Assessment of cellular sensitivity to vinblastine sulfate, paclitaxel, doxorubicin hydrochloride, and daunorubicin hydrochloride.
  • Measurement of [3H]vinblastine sulfate accumulation.
  • Analysis of MDR1 mRNA expression levels.

Main Results:

  • Ca2+ antagonists were classified into four subgroups based on their effects on P-gp transport and drug sensitivity.
  • Previous findings were confirmed using doxorubicin and daunorubicin resistance models.
  • Ca2+ antagonists effectively recovered [3H]vinblastine sulfate accumulation in resistant cells.
  • Sensitivity recovery was correlated with the down-regulation of MDR1 mRNA expression.

Conclusions:

  • Ca2+ antagonists can effectively reverse MDR mediated by P-gp.
  • Down-regulation of MDR1 mRNA represents a novel mechanism by which Ca2+ antagonists overcome MDR.
  • These findings suggest a potential therapeutic strategy for enhancing chemotherapy efficacy in resistant cancers.

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