Superior cytotoxicity and DNA cross-link induction by oxaliplatin versus cisplatin at lower cellular uptake in colorectal cancer cell lines.

Platinum-based chemotherapeutic agents are considered among the most potent anticancer drugs used in the treatment of human tumors. Cisplatin is efficient in the treatment of testicular, ovarian, bladder, and head and neck carcinomas, although its use is limited by severe nephrotoxicity and ototoxicity and resistance. Oxaliplatin has consistently exerted antitumor activity in colon, ovarian, and lung cancers and shown less toxicity than its analogue. Given that most of the literature data are contradictory with respect to the cytotoxicity of these drugs and DNA adduct formation, the present study aimed to determine some of the potential underlying mechanisms in view of their cellular uptakes. We evaluated the cytotoxicity, DNA cross-link formation, and cellular uptake of cisplatin and oxaliplatin in Colo320, HT-29, and Caco-2 colorectal adenocarcinoma cell lines. Our results showed higher cytotoxicity of oxaliplatin in Colo320 (P<0.05) and HT-29 cell lines and of cisplatin in Caco-2 (P<0.05). Oxaliplatin induced more DNA cross-links than cisplatin in a dose-dependent manner in Colo320 cells (P<0.0001); in HT-29 and Caco-2 cells, the induction of DNA damage was not dose dependent. Multiple accumulation of cisplatin versus oxaliplatin occurred in all the cell types, doses, and time points we tested. Oxaliplatin showed more potent biological activities versus cisplatin in terms of a significantly lower cellular uptake. In addition to their analogous mechanisms of action, these drugs might activate different signal transduction pathways, ultimately leading to apoptotic DNA fragmentation and cell death. DNA damage, although perhaps the most important, represents only one aspect of the multiple effects of platinum drugs.