Biological reactive intermediates that mediate dacarbazine cytotoxicity.
OBJECTIVE
In the following, the cellular and molecular mechanism of cytotoxicity induced by prodrug dacarbazine toward the isolated rat hepatocytes was studied.


METHODS
Accelerated cytotoxicity screening technique (ACMS) was used to perform this study.


RESULTS
Addition of dacarbazine to isolated rat hepatocytes resulted in reactive oxygen species (ROS) formation, and lysosomal membrane leakiness before hepatocyte lysis occurred. Hepatocyte ROS generation was inhibited by desferoxamine (a ferric chelator). Cytotoxicity was prevented by antioxidants or ROS scavengers (mannitol or dimethylsulfoxide), cytochorome P450 inhibitors (phenylimidazole, diphenyliodonium chloride, 4-methylpyrazole, and benzylimidazole). In addition to lysosomal damage, dacarbazine caused hepatocyte protease activation and cell proteolysis.


CONCLUSIONS
Dacarbazine cytotoxicity is associated with ROS (H(2)O(2), O(2)(*-) ) generation. It is suggested that H(2)O(2) could cross the lysosomal membrane, react with lysosomal Fe(2+) to form hydroxyl radical (Haber-Weiss reaction) which is the major cause of lysosomal membrane leakiness, proteases, and other digestive enzymes' release and finally the cell death.
Pourahmad
Jalal
J
Faculty of Pharmacy, Shaheed Beheshti University of Medical Sciences, Tehran, PO Box 14155-6153, Iran. j.pourahmadjaktaji@utoronto.ca
Amirmostofian
Marzieh
M
Kobarfard
Farzad
F
Shahraki
Jafar
J
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects; D003606:Dacarbazine / Q000633:toxicity*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D010447:Peptide Hydrolases / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*
D018906:Antineoplastic Agents, Alkylating; D017382:Reactive Oxygen Species; D017665:Hydroxyl Radical; D003606:Dacarbazine; D006861:Hydrogen Peroxide; D007501:Iron; D010447:Peptide Hydrolases