Lambert Laura A, Qiao Na, Hunt Kelly K, Lambert Donald H, Mills Gordon B, Meijer Laurent, Keyomarsi Khandan
Departments of Surgical Oncology, Experimental Radiation Oncology, and Systems Biology, University of Texas - M. D. Anderson Cancer Center, Houston, Texas.
Cancer Res. 2008 Oct 1;68(19):7966-74. doi: 10.1158/0008-5472.CAN-08-1333.
Doxorubicin is a genotoxic chemotherapy agent used in treatment of a wide variety of cancers. Significant clinical side effects, including cardiac toxicity and myelosuppression, severely limit the therapeutic index of this commonly used agent and methods which improve doxorubicin efficacy could benefit many patients. Because doxorubicin cytotoxicity is cell cycle specific, the cell cycle is a rational target to enhance its efficacy. We examined the direct, cyclin-dependent kinase inhibitor roscovitine as a means of enhancing doxorubicin cytotoxicity. This study showed synergistic cytotoxicity between doxorubicin and roscovitine in three sarcoma cell lines: SW-982 (synovial sarcoma), U2OS-LC3-GFP (osteosarcoma), and SK-LMS-1 (uterine leiomyosarcoma), but not the fibroblast cell line WI38. The combined treatment of doxorubicin and roscovitine was associated with a prolonged G(2)-M cell cycle arrest in the three sarcoma cell lines. Using three different methods for detecting apoptosis, our results revealed that apoptotic cell death did not account for the synergistic cytotoxicity between doxorubicin and roscovitine. However, morphologic changes observed by light microscopy and increased cytoplasmic LC3-GFP puncta in U20S-LC3-GFP cells after the combined treatment suggested the induction of autophagy. Induction of autophagy was also shown in SW-982 and SK-LMS-1 cells treated with both doxorubicin and roscovitine by acridine orange staining. These results suggest a novel role of autophagy in the enhanced cytotoxicity by cell cycle inhibition after genotoxic injury in tumor cells. Further investigation of this enhanced cytotoxicity as a treatment strategy for sarcomas is warranted.
阿霉素是一种用于治疗多种癌症的具有基因毒性的化疗药物。包括心脏毒性和骨髓抑制在内的显著临床副作用严重限制了这种常用药物的治疗指数，而提高阿霉素疗效的方法可能会使许多患者受益。由于阿霉素的细胞毒性具有细胞周期特异性，细胞周期是增强其疗效的合理靶点。我们研究了直接的细胞周期蛋白依赖性激酶抑制剂罗可辛作为增强阿霉素细胞毒性的一种手段。本研究表明，阿霉素与罗可辛在三种肉瘤细胞系中具有协同细胞毒性：SW - 982（滑膜肉瘤）、U2OS - LC3 - GFP（骨肉瘤）和SK - LMS - 1（子宫平滑肌肉瘤），但在成纤维细胞系WI38中没有。阿霉素与罗可辛的联合治疗与三种肉瘤细胞系中G(2)-M细胞周期的延长阻滞相关。使用三种不同的检测凋亡的方法，我们的结果显示凋亡性细胞死亡并不能解释阿霉素与罗可辛之间的协同细胞毒性。然而，联合治疗后通过光学显微镜观察到的形态学变化以及U20S - LC3 - GFP细胞中细胞质LC3 - GFP斑点的增加提示了自噬的诱导。吖啶橙染色也显示在同时用阿霉素和罗可辛处理的SW - 982和SK - LMS - 1细胞中存在自噬诱导。这些结果表明自噬在肿瘤细胞基因毒性损伤后通过细胞周期抑制增强细胞毒性中具有新作用。进一步研究这种增强的细胞毒性作为肉瘤的治疗策略是有必要的。
