Byrnes R W, Templin J, Sem D, Lyman S, Petering D H
Department of Chemistry, University of Wisconsin-Milwaukee 53201.
Cancer Res. 1990 Sep 1;50(17):5275-86.
A comparison of the intracellular DNA strand scission activities of the antitumor drug bleomycin, three of its metal complexes, demethyl bleomycin A2, and iron-containing, redox-inactivated bleomycin in Ehrlich ascites tumor cells was performed by means of the alkaline elution technique. This comparison was aided by use of CoCl2 to eliminate or minimize post-cell lysis strand scission by bleomycin in aliquots of treated cultures. No strand scission resulted from treatment of cells with the cobalt complex. The levels of intracellular DNA degradation by copper bleomycin and iron bleomycin were equivalent to those produced by metal-free bleomycin. The findings are correlated with previous measurements of growth inhibition by these three bleomycins as well as by cobalt bleomycin and related to the concentrations of radiolabeled bleomycin bound to DNA after treatment of cells with each form of drug. In comparison, both demethyl bleomycin A2 and iron-containing, redox-inactivated bleomycin showed marked, concentration-dependent reductions in random DNA strand scission, as compared with unmodified bleomycin or iron bleomycin prepared from Fe(III) and bleomycin. However, the fraction of DNA from cells treated with these two bleomycins, which eluted through filters prior to alkaline denaturation, was equivalent to that for unmodified bleomycin and Fe(III)bleomycin. The generation of this class of damaged DNA correlates more closely with concentration-dependent growth inhibition by each of the six forms of bleomycin than the degree of random strand scission.
采用碱性洗脱技术，对博来霉素及其三种金属配合物、去甲基博来霉素A2以及含铁的、氧化还原失活的博来霉素在艾氏腹水瘤细胞中的细胞内DNA链断裂活性进行了比较。通过使用CoCl2来消除或最小化博来霉素在处理过的培养物等分试样中细胞裂解后的链断裂，辅助了这种比较。用钴配合物处理细胞未导致链断裂。铜博来霉素和铁博来霉素引起的细胞内DNA降解水平与无金属博来霉素产生的水平相当。这些发现与先前对这三种博来霉素以及钴博来霉素的生长抑制测量结果相关，并与用每种形式的药物处理细胞后与DNA结合的放射性标记博来霉素的浓度有关。相比之下，与未修饰的博来霉素或由Fe(III)和博来霉素制备的铁博来霉素相比，去甲基博来霉素A2和含铁的、氧化还原失活的博来霉素在随机DNA链断裂方面均表现出明显的浓度依赖性降低。然而，用这两种博来霉素处理的细胞中，在碱性变性之前通过滤膜洗脱的DNA部分与未修饰的博来霉素和Fe(III)博来霉素的相当。与随机链断裂程度相比，这类受损DNA的产生与六种形式的博来霉素各自的浓度依赖性生长抑制更密切相关。
