Detection of sequence-specific antitumor alkylating agent DNA damage from cells treated in culture and from a patient

Detection of sequence-specific DNA damage induced by antitumor alkylating agents might provide a mechanism for detecting and discriminating damage specific to one or more of these drugs. Using repetitive primer-extension and human alphoid DNA as a substrate, lesions specific for an activated form of cyclophosphamide, 4-hydroperoxycyclophosphamide, were detected at 32 of 33 guanines within a 200-base pair region in DNA from cells treated in culture. There was a marked variation in lesion site intensity among affected guanines. For instance, guanines flanked by cytosine were weak sites of 4-hydroperoxycyclophosphamide-induced damage. Damage at bases other than guanine induced by cisplatin, UV irradiation, and adozelesin were compared to drug-DNA lesions induced by 4-hydroperoxycyclophosphamide. Using this method it was possible to detect, and at some sites distinguish, between cyclophosphamide- and cisplatin-induced DNA damage within WBC DNA from a patient treated with both agents. There was a different damage pattern for DNA derived from cells treated in culture compared to DNA derived from the patient sample.