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Specific reversal of MDR1/P-gp-dependent multidrug resistance by RNA interference in colon cancer cells

Zhongsheng Xia1, Zhaohua Zhu, Liyong Zhang

  • 1Department of Gastroenterology, The Second Affiliated Hospital, Sun Yat-sen University, Guangzhou 510120, P.R. China. xiazhsh@hotmail.com

Oncology Reports
|November 21, 2008
PubMed

Insights

This study used small interfering RNA (siRNA) to successfully reverse multidrug resistance (MDR) in colon cancer cells by inhibiting MDR1/P-glycoprotein (P-gp). This approach offers a potential new strategy for treating MDR1/P-gp-dependent multidrug resistance in cancer therapy.

Area of Science:

  • Oncology
  • Molecular Biology
  • Pharmacology

Background:

  • Multidrug resistance (MDR) in cancer, particularly colon cancer, limits the efficacy of chemotherapy.
  • Previous studies lacked appropriate control cell lines for investigating MDR reversal.
  • MDR1/P-glycoprotein (P-gp) is a key efflux pump contributing to MDR in various cancers.

Purpose of the Study:

  • To investigate the reversal of MDR1/P-gp-dependent MDR in colon cancer cells using specific MDR1 siRNAs.
  • To evaluate the efficacy and specificity of two MDR1 siRNAs (#4123 and #4029) in inhibiting MDR1 mRNA and P-gp expression.
  • To assess the impact of MDR1 siRNA treatment on the cytotoxicity of conventional chemotherapeutic agents.

Main Methods:

  • Utilized human COLO 320DM and HT-29 (control) colon cancer cell lines.
  • Employed two MDR1-targeting siRNAs (#4123 and #4029) to inhibit MDR1 mRNA expression.
  • Quantified MDR1 and P-gp expression levels post-siRNA treatment.
  • Assessed the cytotoxicity of adriamycin and vincristine in treated cells.
  • Measured intracellular accumulation of adriamycin.

Main Results:

  • Both MDR1 siRNAs effectively inhibited MDR1 mRNA and P-gp expression in COLO 320DM cells.
  • The minimum inhibitory concentrations were 5 nmol/l for #4123 siRNA and 25 nmol/l for #4029 siRNA.
  • #4123 siRNA demonstrated dose- and time-dependent inhibition of MDR1/P-gp.
  • Inhibition of MDR1/P-gp led to increased cytotoxicity of adriamycin and vincristine.
  • Enhanced intracellular adriamycin accumulation was observed in siRNA-treated cells.
  • No significant effects were observed in the HT-29 control cell line, indicating specificity.

Conclusions:

  • MDR1 siRNAs specifically reverse MDR1/P-gp-dependent multidrug resistance in colon cancer cells.
  • This siRNA-based approach represents a promising new therapeutic strategy for overcoming MDR in colon cancer.
  • The findings support the potential clinical application of MDR1-targeting siRNAs in combination chemotherapy.

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