Bae-Jump Victoria L, Zhou Chunxiao, Gehrig Paola A, Whang Young E, Boggess John F
Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, CB# 7570, Chapel Hill, NC 27599, USA.
Gynecol Oncol. 2006 Mar;100(3):487-94. doi: 10.1016/j.ygyno.2005.08.053. Epub 2005 Oct 24.
Rapamycin and its analogues have been shown to be promising as anti-neoplastic agents but have not been extensively studied in gynecologic malignancies. Our goal was to examine the ability of rapamycin to suppress growth and regulate telomerase activity in cervical and ovarian cancer cell lines.
Cell proliferation was assessed after exposure to rapamycin. Cell cycle progression was determined by flow cytometry, and apoptosis was evaluated by DNA fragmentation. hTERT mRNA levels were quantified by real-time RT-PCR. Western blot analysis was performed to assess PTEN status, phosphorylated S6 and total S6 expression.
Rapamycin inhibited growth of all the cervical cancer cell lines and 3 of the 4 ovarian cancer cell lines in a dose-dependent manner with IC50 values <50 nM. Loss of PTEN protein expression was seen in only one of the cervical cancer cell lines. Rapamycin induced G1 arrest in those cell lines sensitive to its growth inhibitory effects. In all cell lines, rapamycin rapidly inhibited phosphorylation of S6 and resulted in decreased levels of total S6 protein. Treatment with rapamycin reduced hTERT mRNA expression in both rapamycin-sensitive and -resistant cell lines within 24 h. Thus, the effect of rapamycin on hTERT expression was not dependent on its ability to induce G1 cell cycle arrest.
Our data suggest that rapamycin may potentially exert its anti-tumor effects through two independent pathways by G1 cell cycle arrest as well as suppression of telomerase activity by inhibition of hTERT mRNA transcription.
雷帕霉素及其类似物已被证明有望成为抗肿瘤药物，但在妇科恶性肿瘤中的研究尚未广泛开展。我们的目标是研究雷帕霉素抑制宫颈癌和卵巢癌细胞系生长及调节端粒酶活性的能力。
在暴露于雷帕霉素后评估细胞增殖。通过流式细胞术确定细胞周期进程，通过DNA片段化评估细胞凋亡。通过实时RT-PCR定量hTERT mRNA水平。进行蛋白质印迹分析以评估PTEN状态、磷酸化S6和总S6表达。
雷帕霉素以剂量依赖性方式抑制所有宫颈癌细胞系和4个卵巢癌细胞系中的3个的生长，IC50值<50 nM。仅在一个宫颈癌细胞系中观察到PTEN蛋白表达缺失。雷帕霉素在那些对其生长抑制作用敏感的细胞系中诱导G1期阻滞。在所有细胞系中，雷帕霉素迅速抑制S6的磷酸化并导致总S6蛋白水平降低。用雷帕霉素处理在24小时内降低了雷帕霉素敏感和耐药细胞系中的hTERT mRNA表达。因此，雷帕霉素对hTERT表达的影响不依赖于其诱导G1期细胞周期阻滞的能力。
我们的数据表明，雷帕霉素可能通过G1期细胞周期阻滞以及通过抑制hTERT mRNA转录来抑制端粒酶活性这两个独立途径发挥其抗肿瘤作用。
