engleski

DNA damage vs. acetylcholinesterase activity in dacarbazine-treated human blood cells in vitro modulated by photoactivation

Dacarbazine (DTIC) is a methylating agent, generally considered the most active antineoplastic drug for treating malignant melanoma. Clinical studies indicate that its photodegradation products cause adverse reactions when drug is administered to patients. As the molecular structure of DTIC involves carbamate moiety, possible impacts on the acetylcholinesterase (AChE) enzyme are also anticipated. Recent findings point to the role of AChE in cells undergoing apoptosis, but the underlying mechanisms remain to be clarified. Present in vitro study aimed at investigating the relationships between the genotoxicity and AChE activity in DTIC-treated human blood cells and to establish how they are influenced by photoactivation. The alkaline comet assay was used for the evaluation of primary DNA damage in leukocytes, while inhibitory potential of the drug on AChE was studied in erythrocytes by the Ellman method. Blood cells were treated with two therapeutically relevant concentrations of the drug (200 mg/m2 and 350 mg/m2) for 30 and 60 min, with and without photoactivation. The results of alkaline comet assay demonstrated a dose-dependent photogenotoxicity of DTIC, indicating that its degradation products possess higher DNA damaging potential then the parent drug. When photoactivated DTIC-treated cells were transferred in dark and incubated for 60 min, the reduction of DNA damage was noted. AChE activity in DTIC-treated erythrocytes, especially those incubated in dark, was lower than in negative controls, indicating the AChE- inhibiting ability of the agent. As observed, longer photoactivation of DTIC-treated cells was accompanied with the restoration of AChE activity, possibly due to the parent drug deactivation. The results sustain the concurrent evaluation of DNA damage and AChE activity, as both biomarkers used provide much better insight into the mechanisms underlying the drug toxicity, especially in studies on antineoplastic drugs having the potential to modulate AChE.

dacarbazine; AChE; DNA damage

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