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Metabolism of melphalan by rat liver microsomal glutathione S-transferase

Jie Zhang1, Zhiwei Ye, Yijia Lou

  • 1Department of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, 310031 Hangzhou, China.

Chemico-Biological Interactions
|April 21, 2005
PubMed

Insights

Microsomal glutathione S-transferase (GST) may contribute to acquired drug resistance (ADR) by catalyzing melphalan inactivation. This study shows microsomal GST activates melphalan metabolism, potentially impacting cancer treatment outcomes.

Area of Science:

  • Biochemistry
  • Pharmacology
  • Cancer Research

Background:

  • Drug resistance is a major challenge in cancer therapy.
  • Elevated cytosolic glutathione S-transferase (GST) activity is a known mechanism of tumor cell resistance.
  • The role of microsomal GST in acquired drug resistance (ADR) is not well understood.

Purpose of the Study:

  • To investigate the potential involvement of microsomal GST in the metabolism of melphalan and its contribution to ADR.
  • To characterize the reaction products of melphalan and glutathione (GSH).
  • To determine the catalytic effect and activation of microsomal GST by melphalan.

Main Methods:

  • Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) for conjugate structural characterization.
  • In vitro reaction of melphalan with GSH under controlled conditions.
  • Assessment of microsomal GST activity and its modulation by melphalan concentration and time.

Main Results:

  • Melphalan spontaneously reacts with GSH to form monoglutathionyl and diglutathionyl derivatives.
  • Rat liver microsomal GST significantly increased the formation of these GSH-melphalan conjugates.
  • Microsomal GST activity was enhanced by melphalan in a concentration- and time-dependent manner, with a ~1.5-fold stimulation.

Conclusions:

  • Microsomal GST plays a catalytic role in melphalan metabolism within biological membranes.
  • Microsomal GST may be involved in the development of acquired drug resistance to melphalan.
  • Further research into microsomal GST's role could inform strategies to overcome drug resistance in cancer treatment.

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