Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan.
Am J Pathol. 2012 Feb;180(2):862-71. doi: 10.1016/j.ajpath.2011.10.018. Epub 2011 Dec 2.
Radiotherapy is a well established treatment for cervical cancer, the second most common cancer in women worldwide. However, metastasis often circumvents the efficacy of radiotherapy. This study was conducted to elucidate the molecular mechanism of radioresistance-associated metastatic potential of cervical cancer cells. We established three radioresistant cervical cancer cell lines by exposure of cells to a sublethal dose of radiation and screened for lines that exhibited an increased migration phenotype for at least 6 months before undertaking mechanistic studies. Radiation-associated metastatic potential was evaluated using a wound-healing assay, time-lapse recording, and cell locomotion into the lungs of BALB/c nude mice. The radioresistant C33A and CaSki cell lines, but not the radioresistant HeLa cell line, exhibited significantly increased cell migration and wound healing than did wild-type cells. Furthermore, K-Ras played a prometastatic role via the activation of c-Raf/p38, whereas interference of those mediators via either RNA interference-mediated knockdown or the use of chemical inhibitors substantially reversed the radioresistance-associated increase in cell migration. Clinical examination further showed the relative up-regulation of the K-Ras/c-Raf/p38 pathway in locally recurring tumors and distant metastases compared with in the primary cervical tumor. These findings demonstrate that a sublethal dose of radiation can enhance the metastatic potential of human cervical cancer cells via K-Ras/c-Raf/p38 signaling, highlighting the potential development of specific inhibitors for reducing metastatic potential during radiotherapy.
放射疗法是治疗宫颈癌的一种成熟方法，宫颈癌是全球女性中第二大常见癌症。然而，转移往往会规避放射疗法的疗效。本研究旨在阐明与放射抵抗相关的宫颈癌细胞转移潜能的分子机制。我们通过将细胞暴露于亚致死剂量的辐射来建立三种放射抵抗的宫颈癌细胞系，并筛选出至少在进行机制研究之前 6 个月表现出增加的迁移表型的细胞系。使用划痕愈合试验、延时记录和细胞向 BALB/c 裸鼠肺部的迁移来评估放射相关的转移潜能。与野生型细胞相比，放射抵抗的 C33A 和 CaSki 细胞系而非放射抵抗的 HeLa 细胞系表现出明显增加的细胞迁移和伤口愈合。此外，K-Ras 通过激活 c-Raf/p38 发挥促进转移的作用，而通过 RNA 干扰介导的敲低或使用化学抑制剂干扰这些介质可显著逆转放射抵抗相关的细胞迁移增加。临床检查进一步显示，与原发性宫颈癌相比，局部复发肿瘤和远处转移中 K-Ras/c-Raf/p38 通路的相对上调。这些发现表明，亚致死剂量的辐射可以通过 K-Ras/c-Raf/p38 信号增强人类宫颈癌细胞的转移潜能，突出了在放射治疗期间开发特定抑制剂以降低转移潜能的潜力。
