Weaver J R, Gan Y, Au J L
College of Pharmacy, The Ohio State University, Columbus 43210, USA.
Pharm Res. 1998 Oct;15(10):1546-51. doi: 10.1023/a:1011998932047.
The present study compared proliferative indices, i.e. incorporation of DNA precursor (i.e. thymidine or TdR, and bromodeoxyuridine or BrdU) and expression of proliferating cell nuclear antigen (PCNA), as molecular pharmacodynamic endpoints in evaluation of anticancer drug effect in human solid tumors.
Tumor specimens obtained from patients were grown as histocultures. After treatment with doxorubicin, mitomycin C, and/or paclitaxel, cells labeled by [3H]TdR were identified using autoradiography, and cells labeled by BrdU and PCNA were identified using immunohistochemical techniques. Drug effect was measured as reduction of DNA precursor-labeled cells or PCNA-expressing cells.
The results indicate that (a) the two DNA precursors, TdR and BrdU, labeled the same cells and resulted in identical pharmacodynamics, (b) the pharmacodynamics established using inhibition of DNA precursor incorporation were qualitatively and quantitatively different from the pharmacodynamics established using inhibition of PCNA expression, (c) the inhibition of PCNA expression was erratic in some tumors, and (d) the differences in pharmacodynamics established using the two end points are drug-specific, with greater differences for paclitaxel than for mitomycin C.
The erratic results measured by the PCNA labeling method suggest that this method may be less reliable than the conventional DNA precursor labeling method. The finding of identical pharmacodynamics of doxorubicin and paclitaxel established using BrdU and [3H]TdR indicates that the two precursors are interchangeable. Because the methodology for detecting BrdU incorporation requires less time and does not require the use of radioactivity, we conclude that inhibition of BrdU incorporation represents a useful endpoint for evaluating the antiproliferative activity of anticancer drugs in human solid tumors.
本研究比较了增殖指数，即DNA前体（即胸苷或TdR，以及溴脱氧尿苷或BrdU）的掺入和增殖细胞核抗原（PCNA）的表达，作为评估抗癌药物对人类实体瘤疗效的分子药效学终点。
从患者身上获取的肿瘤标本进行组织培养。在用阿霉素、丝裂霉素C和/或紫杉醇处理后，使用放射自显影法鉴定用[3H]TdR标记的细胞，使用免疫组织化学技术鉴定用BrdU和PCNA标记的细胞。通过减少DNA前体标记的细胞或PCNA表达的细胞来测量药物效果。
结果表明：（a）两种DNA前体TdR和BrdU标记相同的细胞，并产生相同的药效学；（b）使用抑制DNA前体掺入建立的药效学在定性和定量上与使用抑制PCNA表达建立的药效学不同；（c）在某些肿瘤中，PCNA表达的抑制不稳定；（d）使用这两个终点建立的药效学差异具有药物特异性，紫杉醇的差异比丝裂霉素C更大。
PCNA标记法测得的不稳定结果表明，该方法可能不如传统的DNA前体标记法可靠。使用BrdU和[3H]TdR建立的阿霉素和紫杉醇相同药效学的发现表明，这两种前体是可互换的。由于检测BrdU掺入的方法所需时间更少，且不需要使用放射性，我们得出结论，抑制BrdU掺入是评估抗癌药物对人类实体瘤抗增殖活性的一个有用终点。
