Department of Biotechnological and Applied Clinical Sciences, Division of Radiotherapy and Radiobiology Laboratory, San Salvatore Hospital, University of L'Aquila, I-67100 L'Aquila, Italy.
Int J Oncol. 2014 Jan;44(1):285-94. doi: 10.3892/ijo.2013.2167. Epub 2013 Nov 5.
Both Aurora-A and -B kinases have been implicated in tumorigenesis; and as such, they represent an attractive therapeutic target. Recent studies found that Aurora-A is a downstream target of mitogen-activated protein kinase 1/ERK2, while Aurora-B has been found to be a prognostic/predictive therapeutic target for epithelial cancer. In a wide range of human cancers, the Ras/Raf/MEK/ERK/MAP kinase pathway is enhanced and the cellular response to growth signals is known to increase. The purpose of this study was to investigate whether the MEK/ERK cascade regulates tumorigenic signaling and radioresistance via the Aurora-B-mediated pathway in a panel of gynecological cancer cell lines. Exponentially growing human endometrial (Ishikawa), cervical (HeLa), cervical (CASKI) and vulva (SiHa) cancer cells were used in culture treated with either control or MEK/ERK inhibitor or AZD1152 before and after irradiation. Western blotting, ERK1/2 siRNA transfection, growth assay in modified monolayer, Annexin V and migration/invasion assays were performed. The specific MEK/ERK inhibitor U0126 decreased the tumorigenic potential and improved the radiation response in all cellular models. The modulation of radioresponse upon U0126 treatment positively correlated with the inhibition of phospho-ERKs and the reduction of Aurora-B kinase expression. In addition, upon U0126 treatment DNA-PKcs protein expression was found to be downregulated, indicating that the improved radiation response may be caused by decreased DNA double-strand damage repair mechanisms. The knockdown of ERK by siRNA confirmed the MEK/ERK-dependent Aurora-B kinase expression. The use of AZD1152, a selective Aurora-B inhibitor, counteracted tumorigenic potential and radioresistance phenotype by highly increasing apoptotic mechanisms in all gynecological cancer cell lines used. Evidence from our experiments show that tumorigenic potential and radiation response in gynecological cancer cells may ensue from a MEK/ERK or Aurora-B inhibition. Together with the close correlation of MEK/ERK and Aurora-B protein expression, this study underlines the potential role of a MEK/ERK/Aurora-B axis whose interruption recovers the antitumor effects of radiotherapy.
极光激酶-A 和 -B 都与肿瘤发生有关；因此，它们是一个有吸引力的治疗靶点。最近的研究发现，极光激酶-A 是丝裂原活化蛋白激酶 1/ERK2 的下游靶点，而极光激酶-B 已被发现是上皮癌的预后/预测治疗靶点。在广泛的人类癌症中，Ras/Raf/MEK/ERK/MAP 激酶途径增强，细胞对生长信号的反应已知会增加。本研究旨在探讨 MEK/ERK 级联是否通过极光激酶-B 介导的途径调节一组妇科癌细胞系中的致瘤信号和放射抗性。在培养中使用指数生长的人子宫内膜（Ishikawa）、宫颈（HeLa）、宫颈（CASKI）和外阴（SiHa）癌细胞，用对照或 MEK/ERK 抑制剂或 AZD1152 处理，然后进行照射前后处理。进行 Western blot、ERK1/2 siRNA 转染、改良单层生长测定、Annexin V 和迁移/侵袭测定。特异性 MEK/ERK 抑制剂 U0126 降低了所有细胞模型的致瘤潜力并改善了放射反应。U0126 处理后放射反应的调节与磷酸化 ERKs 的抑制和极光激酶-B 表达的减少呈正相关。此外，在用 U0126 处理后发现 DNA-PKcs 蛋白表达下调，表明改善的放射反应可能是由于 DNA 双链断裂修复机制减少所致。siRNA 敲低 ERK 证实了 MEK/ERK 依赖性极光激酶-B 表达。使用选择性极光激酶-B 抑制剂 AZD1152，通过高度增加所有妇科癌细胞系中的凋亡机制，抵消了致瘤潜力和放射抗性表型。我们实验的证据表明，妇科癌细胞的致瘤潜力和放射反应可能源于 MEK/ERK 或极光激酶-B 的抑制。MEK/ERK 和极光激酶-B 蛋白表达的密切相关性表明，该研究强调了 MEK/ERK/Aurora-B 轴的潜在作用，其阻断可恢复放射治疗的抗肿瘤作用。
