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Multidrug-resistant protein-3 gene regulation by the transcription factor Nrf2 in human bronchial epithelial and

Christopher M Mahaffey1, Hongqiao Zhang, Alessandra Rinna

  • 1Department of Natural Sciences, University of California at Merced, Merced, CA 95344, USA.

Free Radical Biology & Medicine
|April 7, 2009
PubMed

Insights

Multidrug-resistant protein 3 (MRP3) is upregulated by the electrophilic compound HNE via the transcription factor Nrf2, particularly in cells with functional Keap1. This Nrf2-MRP3 pathway influences chemotherapy drug resistance in non-small-cell lung cancer.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Multidrug-resistant proteins (MRPs) are ATP-binding cassette transporters crucial for cellular detoxification, exporting xenobiotics like chemotherapy drugs.
  • Increased MRP levels are observed under stress, but the regulatory mechanisms, especially for MRP3 in non-small-cell lung carcinoma (NSCLC), are unclear.
  • The transcription factor Nrf2, known to regulate genes with electrophile-responsive elements (EpREs), is a potential regulator of MRP3.

Purpose of the Study:

  • To investigate if the induction of MRP3 is dependent on the transcription factor Nrf2.
  • To elucidate the role of Keap1 and the electrophilic compound 4-hydroxy-2-nonenal (HNE) in MRP3 regulation.

Main Methods:

  • Analysis of the MRP3 promoter for EpREs.
  • Treatment of cell lines (HBE1, H358, A549, H460) with HNE.
  • Assessment of MRP3 mRNA and protein levels.
  • Gene silencing of Nrf2 using siRNA.
  • Evaluation of cisplatin toxicity in Nrf2-silenced cells.

Main Results:

  • HNE upregulated MRP3 in cell lines with wild-type Keap1 but not in Keap1-mutant lines.
  • Mutant Keap1 cell lines exhibited higher basal MRP3 levels.
  • Nrf2 silencing inhibited HNE-induced MRP3 upregulation in HBE1 cells.
  • Nrf2 silencing increased cisplatin toxicity in H358 cells.

Conclusions:

  • MRP3 induction by HNE is mediated through Nrf2 activation.
  • The Keap1-Nrf2 pathway is critical for regulating MRP3 expression in response to electrophilic stress.
  • Nrf2-dependent MRP3 expression plays a role in modulating chemotherapy drug sensitivity, particularly in NSCLC.

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