Nakayama Satoshi, Torikoshi Yasuhiro, Takahashi Takeshi, Yoshida Tomokazu, Sudo Tamotsu, Matsushima Tomoko, Kawasaki Yuko, Katayama Aya, Gohda Keigo, Hortobagyi Gabriel N, Noguchi Shinzaburo, Sakai Toshiyuki, Ishihara Hideki, Ueno Naoto T
Central Research Laboratories, Sysmex Corporation, 4-4-4, Takatsukadai, Nishi-ku, Kobe, Japan.
Breast Cancer Res. 2009;11(1):R12. doi: 10.1186/bcr2231. Epub 2009 Feb 24.
Paclitaxel is used widely in the treatment of breast cancer. Not all tumors respond to this drug, however, and the characteristics that distinguish resistant tumors from sensitive tumors are not well defined. Activation of the spindle assembly checkpoint is required for paclitaxel-induced cell death. We hypothesized that cyclin-dependent kinase (CDK) 1 activity and CDK2 activity in cancer cells, which reflect the activation state of the spindle assembly checkpoint and the growth state, respectively, predict sensitivity to paclitaxel.
Cell viability assays and DNA and chromatin morphology analyses were performed in human breast cancer cell lines to evaluate sensitivity to paclitaxel and the cell cycle response to paclitaxel. We then examined the specific activities of CDK1 and CDK2 in these cell lines and in xenograft models of human breast cancer before and after paclitaxel treatment. Protein expression and kinase activity of CDKs and cyclins were analyzed using a newly developed assay system.
In the cell lines, biological response to paclitaxel in vitro did not accurately predict sensitivity to paclitaxel in vivo. Among the breast cancer xenograft tumors, however, tumors with significantly increased CDK1 specific activity after paclitaxel treatment were sensitive to paclitaxel in vivo, whereas tumors without such an increase were resistant to paclitaxel in vivo. Baseline CDK2 specific activity was higher in tumors that were sensitive to paclitaxel than in tumors that were resistant to paclitaxel.
The change in CDK1 specific activity of xenograft tumors after paclitaxel treatment and the CDK2 specific activity before paclitaxel treatment are both associated with the drug sensitivity in vivo. Analysis of cyclin-dependent kinase activity in the clinical setting could be a powerful approach for predicting paclitaxel sensitivity.
紫杉醇广泛用于乳腺癌治疗。然而，并非所有肿瘤都对该药物有反应，且区分耐药肿瘤与敏感肿瘤的特征尚未明确界定。紫杉醇诱导的细胞死亡需要纺锤体组装检查点的激活。我们假设癌细胞中的细胞周期蛋白依赖性激酶（CDK）1活性和CDK2活性分别反映纺锤体组装检查点的激活状态和生长状态，可预测对紫杉醇的敏感性。
在人乳腺癌细胞系中进行细胞活力测定以及DNA和染色质形态分析，以评估对紫杉醇的敏感性和对紫杉醇的细胞周期反应。然后，我们检测了这些细胞系以及人乳腺癌异种移植模型在紫杉醇治疗前后CDK1和CDK2的比活性。使用新开发的检测系统分析CDK和细胞周期蛋白的蛋白表达及激酶活性。
在细胞系中，体外对紫杉醇的生物学反应并不能准确预测体内对紫杉醇的敏感性。然而，在乳腺癌异种移植肿瘤中，紫杉醇治疗后CDK1比活性显著增加的肿瘤在体内对紫杉醇敏感，而未出现这种增加的肿瘤在体内对紫杉醇耐药。对紫杉醇敏感的肿瘤的基线CDK2比活性高于对紫杉醇耐药的肿瘤。
紫杉醇治疗后异种移植肿瘤的CDK1比活性变化以及紫杉醇治疗前的CDK2比活性均与体内药物敏感性相关。在临床环境中分析细胞周期蛋白依赖性激酶活性可能是预测紫杉醇敏感性的有效方法。
