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From amplification to function: the case of the MDR1 gene

I B Roninson1

  • 1Department of Genetics, University of Illinois, Chicago 60612.

Mutation Research
|May 1, 1992
PubMed

Insights

Gene amplification of the MDR1 gene leads to multidrug resistance in cell lines by increasing P-glycoprotein efflux pumps. This MDR1 gene amplification is linked to chromosomal changes, but increased expression, not amplification, is key for drug resistance in cancer.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • Multidrug resistance (MDR) is a major challenge in cancer chemotherapy.
  • The MDR1 gene, encoding P-glycoprotein, is a key factor in cellular drug efflux.
  • Gene amplification is a known mechanism for acquiring drug resistance in cell lines.

Purpose of the Study:

  • To review the characteristics of gene amplification in multidrug-resistant cell lines.
  • To elucidate the role of the MDR1 gene and P-glycoprotein in multidrug resistance.
  • To explore the relationship between MDR1 gene amplification, expression, and clinical drug resistance.

Main Methods:

  • Review of literature on gene amplification and multidrug resistance.
  • Analysis of studies identifying the MDR1 gene in amplified DNA segments (amplicons).
  • Examination of the correlation between MDR1 gene expression levels and the multidrug-resistant phenotype.

Main Results:

  • Multidrug-resistant cell lines often exhibit multiple copies of the MDR1 gene.
  • Increased MDR1 gene expression, not necessarily amplification, confers the multidrug-resistant phenotype.
  • MDR1 amplification is associated with chromosomal alterations and specific recombination events.
  • While MDR1 amplification is not found in clinical tumors, elevated MDR1 expression is common in cancers and linked to drug resistance.

Conclusions:

  • Gene amplification of MDR1 is a significant mechanism driving multidrug resistance in experimental cell lines.
  • Elevated MDR1 expression is a critical determinant of clinical drug resistance in various cancers, irrespective of gene amplification.
  • Understanding MDR1 regulation is crucial for overcoming therapeutic challenges in oncology.

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