Oliveras-Ferraros Cristina, Vazquez-Martin Alejandro, Colomer Ramon, De Llorens Rafael, Brunet Joan, Menendez Javier A
Metabolism and Cancer Laboratory, Girona Biomedical Research Institute (IdIBGi), Dr Josep Trueta University Hospital of Girona, Catalonia, Spain.
Int J Oncol. 2008 Jan;32(1):113-20.
The marked clinical anticancer activity of the paclitaxel (PTX) and gemcitabine (GEM) combination has suggested that the two drugs may interact more than additively. We have analyzed the in vitro growth and molecular interactions of the two chemotherapy drugs in a panel of human breast cancer cells. We evaluated cell viability in four breast cancer cell lines (i.e., MCF-7, MDA-MB-231, MDA-MB-468, and SKBR3) that were treated with PTX and GEM combined either simultaneously (PTX + GEM) or sequentially (PTX --> GEM; GEM --> PTX). PTX-GEM interactions at the cellular level were assessed mathematically employing both the isobologram analysis (Berenbaum) and the combination index (Chou-Talalay) method. PTX-GEM molecular interactions on the apoptotic markers PARP, Bcl-2 and Bax were analyzed by immunoblotting procedures. Apoptosis was detected using a DNA ladder assay. We observed significant synergistic growth inhibitory interactions when PTX was administered before GEM. Additive interactions were observed when both the simultaneous regimen and the GEM followed by PTX regimen were used. DNA ladder and Western blotting results in the PTX followed by GEM sequence revealed a significant increase in the apoptotic cell death of breast cancer cells related to the Bax/Bcl-2 apoptotic pathway. In summary, the occurrence of clinically relevant synergism between PTX and GEM suggests a sequence-dependent nature in human breast cancer cells. This synergistic interaction on the PTXright curved arrow GEM schedule appears to be related to an increase in the Bcl-2-related mitochondrial apoptotic pathway. The synergism that we have observed may explain the favorable clinical responses that have been achieved in clinical studies, in which patients are administered PTX first, and then GEM.
紫杉醇（PTX）与吉西他滨（GEM）联合使用时显著的临床抗癌活性表明，这两种药物的相互作用可能不止是简单相加。我们分析了这两种化疗药物在一组人乳腺癌细胞中的体外生长及分子相互作用。我们评估了四种乳腺癌细胞系（即MCF-7、MDA-MB-231、MDA-MB-468和SKBR3）的细胞活力，这些细胞系分别接受PTX和GEM同时联合处理（PTX + GEM）或序贯处理（PTX→GEM；GEM→PTX）。采用等效线图分析（贝伦鲍姆法）和联合指数（周-塔拉莱法）从数学角度评估PTX-GEM在细胞水平的相互作用。通过免疫印迹法分析PTX-GEM对凋亡标志物聚（ADP-核糖）聚合酶（PARP）、Bcl-2和Bax的分子相互作用。使用DNA梯状条带分析法检测细胞凋亡。我们观察到，当PTX在GEM之前给药时，存在显著的协同生长抑制相互作用。当采用同时给药方案以及GEM后接PTX的方案时，观察到相加相互作用。PTX后接GEM序列的DNA梯状条带分析和蛋白质免疫印迹结果显示，与Bax/Bcl-2凋亡途径相关的乳腺癌细胞凋亡性细胞死亡显著增加。总之，PTX与GEM之间临床相关协同作用的出现表明，在人乳腺癌细胞中存在序列依赖性。PTX→GEM方案中的这种协同相互作用似乎与Bcl-2相关的线粒体凋亡途径增加有关。我们观察到的这种协同作用可能解释了在临床研究中所取得的良好临床反应，即在临床研究中，患者先接受PTX治疗，然后接受GEM治疗。
