Cell strains derived by culture of malignant glioma (astrocytoma grade III–IV) surgical specimens were tested for the production of DNA interstrand cross-links (ISC) and DNA-protein cross-links following treatment in vitro with 1-(2-chloroethyl)-1-nitrosourea, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine), 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)-1-nitrosourea (PCNU), cis-dichlorodiammineplatinum(II) (cisplatin), and 3,6-diaziridinyl-2,5-bis(carboethoxyamino)-1,4-benzoquinone (diaziquone). ISC and DNA-protein crosslinks were measured by means of the DNA alkaline elution technique. Large differences among the cell strains were observed in DNA cross-linking responses to individual agents. The DNA responses to the chloroethylnitrosoureas, cisplatin, and diaziquone were largely independent of each other, except for a weak correlation between ISC responses to chloroethylnitrosoureas and cisplatin. ISC responses among the cell strains to chloroethylnitrosoureas were distributed bimodally, in accord with a phenotypic distinction between Mer+ and Mer- cells. ISC responses to cisplatin and diaziquone showed significant variation among cell strains, but the distributions were not bimodal. The results demonstrate the existence of diverse DNA cross-linking response patterns among cell strains from different tumors of a given histological type.

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