Miller B E, Miller F R, Machemer T, Heppner G H
Breast Cancer Program, Meyer L. Prentis Comprehensive Cancer Center of Metropolitan Detroit, Michigan 48201.
Br J Cancer. 1993 Jul;68(1):18-25. doi: 10.1038/bjc.1993.280.
In order to examine in detail the sensitivity to chemotherapy of tumour cells at various organ sites and at various stages of metastasis, we have used a series of cell lines, all selected from sister subpopulations derived from a single mouse mammary tumour, which can be distinguished and quantitated from normal cells and from each other through growth in selective medium. For the studies described here, we used two lines, 4T07 and 66FAR, which will form colonies in vitro in medium containing 60 microM 6-thioguanine or 330 microM 2,6-diaminopurine, respectively. Both cell lines have similar sensitivity to the test chemotherapeutic agent, melphalan, in vitro. These two tumour cell lines were treated with melphalan in vivo, when growing either in lungs as experimental metastases at various times after cell injection or as palpable tumours growing subcutaneously. Responses to various doses of melphalan were measured by removing lungs or subcutaneous tumours and performing colony-forming assays in selective medium. The data indicate marked shifts in sensitivity as a function of metastatic stage. Analyses of dose-response curves show that both cell lines were similarly sensitive to melphalan at early times (45 min) after cell injection i.v. but became less sensitive at an intermediate time after injection (3 days). Differences between the two lines became apparent at later times after i.v. injection (by day 8 or 9) and in subcutaneous tumours, where a marked reduction in the shoulder of the dose response curve was seen in line 4T07, resulting in sensitivity equal to or greater than the of early times, whereas the dose response parameters of 66FAR remained at those of the intermediate time point. These results show that, in heterogeneous tumours, individual subpopulations of tumour cells may respond differently to chemotherapeutic agents at various disease stages. In vitro measures of tumour sensitivity do not predict these changes in in vivo sensitivity. Model systems similar to the one described here may yield information which will eventually be useful in maximising the efficacy of clinically relevant adjuvant chemotherapy regimens.
为了详细研究不同器官部位以及转移不同阶段的肿瘤细胞对化疗的敏感性，我们使用了一系列细胞系，所有细胞系均选自由单个小鼠乳腺肿瘤衍生的姐妹亚群，通过在选择性培养基中生长，可将其与正常细胞区分开来并进行定量，彼此之间也能区分。对于此处描述的研究，我们使用了两个细胞系，4T07和66FAR，它们分别在含有60微摩尔6 - 硫鸟嘌呤或330微摩尔2,6 - 二氨基嘌呤的培养基中能够在体外形成集落。这两个细胞系在体外对测试化疗药物美法仑具有相似的敏感性。当这两种肿瘤细胞系在体内生长时，无论是作为细胞注射后不同时间在肺部形成的实验性转移灶，还是作为皮下生长的可触及肿瘤，都用美法仑进行处理。通过切除肺部或皮下肿瘤并在选择性培养基中进行集落形成测定来测量对不同剂量美法仑的反应。数据表明敏感性随转移阶段而显著变化。剂量反应曲线分析表明，两种细胞系在静脉注射细胞后的早期（45分钟）对美法仑同样敏感，但在注射后的中间时间（3天）变得不那么敏感。静脉注射后较晚时间（第8天或第9天）以及皮下肿瘤中，两种细胞系之间的差异变得明显，其中在4T07细胞系中剂量反应曲线的肩部明显降低，导致敏感性等于或高于早期，而66FAR的剂量反应参数则保持在中间时间点的水平。这些结果表明，在异质性肿瘤中，肿瘤细胞的各个亚群在疾病的不同阶段对化疗药物的反应可能不同。肿瘤敏感性的体外测量无法预测体内敏感性的这些变化。类似于此处描述的模型系统可能会产生最终有助于最大化临床相关辅助化疗方案疗效的信息。
