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Updated: May 28, 2026
Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling
Published on: March 20, 2018
Debio 0507 primarily forms diaminocyclohexane-Pt-d(GpG) and -d(ApG) DNA adducts in HCT116 cells
C L King1, S Ramachandran, S G Chaney
1Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, CB #7260, Genetic Medicine Building, Chapel Hill, NC, 27599-7260, USA.
Purpose:
To characterize the cellular action mechanism of Debio 0507, we compared the major DNA adducts formed by Debio 0507- and oxaliplatin-treated HCT116 human colon carcinoma cells by a combination of inductively coupled plasma mass spectrometry (ICP-MS) and ultraperformance liquid chromatography mass spectrometry (UPLC-MS/MS).
Methods:
HCT116 cells were treated with IC(50) doses of Debio 0507 or oxaliplatin for 3 days. Total cellular Pt-DNA adducts were determined by ICP-MS. The DNA was digested, and the major Pt-DNA adducts formed by both drugs were characterized by UPLC/MS/MS essentially as described previously for cisplatin (Baskerville-Abraham et al. in Chem Res Toxicol 22:905-912, 2009).
Results:
The Pt level/deoxynucleotide was 7.4/10(4) for DNA from Debio 0507-treated cells and 5.5/10(4) for oxaliplatin-treated cells following a 3-day treatment at the IC(50) for each drug. UPLC-MS/MS in the positive ion mode confirmed the major Pt-DNA adducts formed by both drugs were dach-Pt-d(GpG) (904.2 m/z → 610 m/z and 904.2 m/z → 459 m/z) and dach-Pt-d(ApG) (888.2 m/z → 594 m/z and 888.2 m/z → 459 m/z).
Conclusions:
These data show that the major DNA adducts formed by Debio 0507 are the dach-Pt-d(GpG) and dach-Pt-d(ApG) adducts and at equitoxic doses Debio 0507 and oxaliplatin form similar levels of dach-Pt-d(GpG) and dach-Pt-d(ApG) adducts. This suggests that the action mechanisms of Debio 0507 and oxaliplatin are similar at a cellular level.
