Combined EGFR and Autophagy Modulation Impairs Cell Migration and Enhances Radiosensitivity in Human Glioblastoma Cells
Combined EGFR and Autophagy Modulation Impairs Cell Migration and Enhances Radiosensitivity in Human Glioblastoma Cells
复制标题
DOI：
10.1002/jcp.24640
复制
发表时间：
2014-11-01
影响因子：
5.6
通讯作者：
Pirtoli, Luigi
中科院分区：
文献类型：
--
作者：
Palumbo, Silvia;Tini, Paolo;Pirtoli, Luigi
胶质母细胞瘤(GBM)是最具侵袭性和致命性的脑肿瘤，由于其分子的异质性及其细胞的高度迁移和侵袭能力，导致其对目前的标准治疗(手术、电离辐射联合替莫唑胺化疗)具有很高的抵抗力。表皮生长因子受体(EGFR)的基因扩增、基因过度表达和基因突变是GBM的特征，它可以异位激活PI3K/Akt/mTOR通路等下游致癌信号级联反应。重要的是，这一途径的改变也参与了自噬过程的调节，可以改善GBM细胞的辐射抗性，从而促进该肿瘤的侵袭性表型。在这项工作中，内源性EGFR的表达谱和自噬被调节以增加人T98G和U373 MG GBM细胞的放射敏感性。我们的结果初步表明，EGFR干扰通过降低被研究细胞的克隆形成能力和有效地减少体外迁移特征来诱导放射敏感性。此外，EGFR干扰导致替莫唑胺(TMZ)对T98G耐药细胞的细胞毒作用增强。为了阐明自噬过程在受EGFR干扰的细胞中起促进死亡或促进生存的作用，关键的自噬基因ATG7被沉默，从而产生自噬过程的一过性阻断。这种自噬抑制挽救了照射和EGFR沉默的T98G细胞的克隆形成能力，表明自噬对死亡有贡献。为了进一步证实EGFR和自噬通路之间的功能相互作用，在EGFR调节过程中雷帕霉素介导的自噬诱导促进了受照射细胞在克隆形成和迁移能力方面的进一步损害。综上所述，这些结果可能建议一种新的联合EGFR-自噬调节策略，以克服固有的GBM辐射抵抗，从而提高标准治疗的疗效。(C)2014年威利期刊公司。
Glioblastoma (GBM) remains the most aggressive and lethal brain tumor due to its molecular heterogeneity and high motility and invasion capabilities of its cells, resulting in high resistance to current standard treatments (surgery, followed by ionizing radiation combined with Temozolomide chemotherapy administration). Locus amplification, gene overexpression, and genetic mutations of epidermal growth factor receptor (EGFR) are hallmarks of GBM that can ectopically activate downstream signaling oncogenic cascades such as PI3K/Akt/mTOR pathway. Importantly, alteration of this pathway, involved also in the regulation of autophagy process, can improve radioresistance in GBM cells, thus promoting the aggressive phenotype of this tumor. In this work, the endogenous EGFR expression profile and autophagy were modulated to increase radiosensitivity behavior of human T98G and U373MG GBM cells. Our results primarily indicated that EGFR interfering induced radiosensitivity according to a decrease of the clonogenic capability of the investigated cells, and an effective reduction of the in vitro migratory features. Moreover, EGFR interfering resulted in an increase of Temozolomide (TMZ) cytotoxicity in T98G TMZ-resistant cells. In order to elucidate the involvement of the autophagy process as pro-death or pro-survival role in cells subjected to EGFR interfering, the key autophagic gene ATG7 was silenced, thereby producing a transient block of the autophagy process. This autophagy inhibition rescued clonogenic capability of irradiated and EGFR-silenced T98G cells, suggesting a pro-death autophagy contribution. To further confirm the functional interplay between EGFR and autophagy pathways, Rapamycin-mediated autophagy induction during EGFR modulation promoted further impairment of irradiated cells, in terms of clonogenic and migration capabilities. Taken together, these results might suggest a novel combined EGFR-autophagy modulation strategy, to overcome intrinsic GBM radioresistance, thus improving the efficacy of standard treatments. (C) 2014 Wiley Periodicals, Inc.