Debio 0507 primarily forms diaminocyclohexane-Pt-d(GpG) and -d(ApG) DNA adducts in HCT116 cells

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.