Development of a liquid chromatography-electrospray ionization tandem mass spectrometry method for detecting...

Area of Science:

• Biochemistry
• Pharmacology
• Genotoxicology

Background:

• Platinum-based chemotherapy, including oxaliplatin, is crucial for cancer treatment.
• Cellular resistance mechanisms can limit the effectiveness of these drugs.
• Oxaliplatin exerts its cytotoxic effect by forming DNA adducts, primarily intrastrand cross-links.

Purpose of the Study:

• To develop and validate a sensitive LC-ESI-MS/MS method for quantifying oxaliplatin-induced DNA intrastrand cross-links (GG and AG).
• To investigate the formation and persistence of these DNA adducts in different tissues of wild-type and GSTP null mice.
• To assess the role of glutathione transferase P (GSTP) in cellular response to oxaliplatin-induced DNA damage.

Main Methods:

• Development of a liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) assay.
• Quantification of GG-oxaliplatin and AG-oxaliplatin adducts in DNA isolated from mouse liver, kidney, and lung.
• Comparison of adduct levels between wild-type and GSTP null mouse strains following oxaliplatin treatment.

Main Results:

• The LC-ESI-MS/MS method achieved limits of detection of 23 adducts/10^8 nucleotides for GG-oxPt and 19 adducts/10^8 nucleotides for AG-oxPt.
• No significant differences in the formation or persistence of oxaliplatin-induced intrastrand cross-links were observed between wild-type and GSTP null mice.
• DNA adduct levels were highest in the liver and lowest in the lung tissue across both mouse strains.

Conclusions:

• The developed LC-ESI-MS/MS method is suitable for sensitive detection of oxaliplatin-DNA adducts.
• Glutathione transferase P does not appear to play a significant role in the formation or persistence of oxaliplatin-induced intrastrand cross-links in the studied tissues.
• Tissue-specific differences in adduct levels suggest varying susceptibility or repair capacities, with implications for understanding oxaliplatin pharmacodynamics and resistance.