Lazo J S, Braun I D, Labaree D C, Schisselbauer J C, Meandzija B, Newman R A, Kennedy K A
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Cancer Res. 1989 Jan 1;49(1):185-90.
Three bleomycin (BLM)-resistant sublines were isolated from a human head and neck squamous cell carcinoma cell line (A-253); these sublines (C-10, D-10, and G-11) were 4-, 9-, and 21-fold resistant to BLM A2, respectively. These sublines were selectively resistant to other members of the BLM class, namely BLM B2, peplomycin, talisomycin S10b, and bleomycinic acid; none of the sublines displayed cross-resistance to vincristine, doxorubicin, cis-diamminedichloroplatinum or melphalan; only one subline (G-11) was cross-resistant to X-irradiation. None of the BLM-resistant cell lines demonstrated resistance to the novel BLM analogue liblomycin, which contains a lipophilic terminal amine. The cell cycle distributions of the clonally derived BLM-resistant cell populations were similar to the distribution of the parental cell population. In vitro BLM hydrolase activity in homogenates of D-10 and G-11 BLM-resistant cell lines was two- to threefold higher than that in homogenates of A-253 or C-10 cells. Nonetheless, no deamido BLM A2 was found associated with any cell type or in the culture medium and more than 80% of the radioactivity in all cells appeared as unmetabolized BLM A2 by high pressure liquid chromatography. Thus, the appearance of large quantities of the deamido BLM metabolite was not a prominent feature of acquired resistance to BLM in these human tumor cells. The cellular accumulation of radiolabeled BLM A2 by C-10 and G-11 cells during a 1-h incubation with [3H]BLM A2 was 1/2 that seen with A-253 and D-10 cells. C-10 cells maintained a lower nuclear content of radioactivity than A-253, G-11, or D-10 cells. Initial single strand DNA damage, based upon alkaline elution analysis, also was lower in C-10 cells compared to A-253 cells. D-10 cells, in contrast, exhibited high initial genomic DNA damage but demonstrated a greater repair rate than either A-253 or C-10 cells. Thus, multiple BLM-resistant phenotypes can be obtained from a population of human squamous carcinoma cells, and modification of the terminal amine in the BLM molecule can produce compounds capable of circumventing all of these BLM-resistant phenotypes. Liblomycin, which appears to be a nonclassical BLM, may be a useful therapeutic agent with a spectrum of activity distinct from other members of the BLM class.
从人头颈鳞状细胞癌细胞系（A - 253）中分离出三个博来霉素（BLM）抗性亚系；这些亚系（C - 10、D - 10和G - 11）对BLM A2的抗性分别为4倍、9倍和21倍。这些亚系对BLM类的其他成员具有选择性抗性，即BLM B2、培洛霉素、他利霉素S10b和博来霉素酸；没有一个亚系对长春新碱、阿霉素、顺二氨二氯铂或美法仑表现出交叉抗性；只有一个亚系（G - 11）对X射线具有交叉抗性。没有一个BLM抗性细胞系对含有亲脂性末端胺的新型BLM类似物利布洛霉素表现出抗性。克隆衍生的BLM抗性细胞群体的细胞周期分布与亲本细胞群体的分布相似。D - 10和G - 11 BLM抗性细胞系匀浆中的体外BLM水解酶活性比A - 253或C - 10细胞匀浆中的高两到三倍。尽管如此，在任何细胞类型或培养基中均未发现脱氨基BLM A2，并且通过高压液相色谱法，所有细胞中超过80%的放射性表现为未代谢的BLM A2。因此，大量脱氨基BLM代谢物的出现并非这些人类肿瘤细胞对BLM获得性抗性的突出特征。在用[³H]BLM A2孵育1小时期间，C - 10和G - 11细胞对放射性标记的BLM A2的细胞积累量是A - 253和D - 10细胞的1/2。C - 10细胞的细胞核放射性含量低于A - 253、G - 11或D - 10细胞。基于碱性洗脱分析，C - 10细胞中的初始单链DNA损伤也低于A - 253细胞。相比之下，D - 10细胞表现出较高的初始基因组DNA损伤，但修复率比A - 253或C - 10细胞更高。因此，可以从一群人鳞状癌细胞中获得多种BLM抗性表型，并且BLM分子中末端胺的修饰可以产生能够规避所有这些BLM抗性表型的化合物。利布洛霉素似乎是一种非经典的BLM，可能是一种有用的治疗药物，其活性谱与BLM类的其他成员不同。
