Growth inhibition and radiosensitization of glioblastoma and lung cancer cells by small interfering RNA silencing of tumor necrosis factor receptor-associated factor 2.
Growth inhibition and radiosensitization of glioblastoma and lung cancer cells by small interfering RNA silencing of tumor necrosis factor receptor-associated factor 2.
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DOI：
10.1158/0008-5472.can-08-0632
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发表时间：
2008-09-15
期刊：
影响因子：
11.2
通讯作者：
Sun Y
中科院分区：
文献类型：
--
作者：
Zheng M;Morgan-Lappe SE;Yang J;Bockbrader KM;Pamarthy D;Thomas D;Fesik SW;Sun Y
放射治疗联合化疗是胶质母细胞瘤和局部晚期肺癌的治疗选择，但这两种类型的癌症的放射抗性仍然是一个显着的治疗障碍。为了鉴定放射增敏的分子靶点，我们筛选了靶向人类基因组中所有蛋白激酶和E3泛素连接酶的siRNA文库，并鉴定了TRAF 2（TNF受体相关因子2）。使用siRNA沉默TRAF 2引起胶质母细胞瘤U251细胞的显著生长抑制，并适度地使这些放射抗性细胞对放射敏感。RING缺失的显性负性TRAF 2突变体的过表达也赋予辐射敏感性;而野生型TRAF 2的过表达显著保护细胞免受辐射诱导的杀伤。同样，siRNA沉默TRAF 2在放射抗性肺癌H1299细胞中引起生长抑制和放射增敏，而野生型TRAF 2的过表达以RING连接酶依赖的方式增强放射抗性。此外，UM-SCC-1头颈癌细胞中TRAF 2的siRNA沉默也赋予放射增敏作用。TRAF 2在癌症中的作用的进一步支持来自于TRAF 2在肺腺癌组织和多种肺癌细胞系中过表达的观察结果。重要的是，TRAF 2在正常支气管上皮NL 20细胞中的表达非常低，并且TRAF 2沉默对NL 20生长和辐射敏感性的影响最小。从机制上讲，TRAF 2沉默阻断了NF-κ B信号通路的激活，并下调了许多G2/M细胞周期控制蛋白，导致G2/M阻滞、生长抑制和放射增敏作用增强。我们的研究表明，TRAF 2是一个有吸引力的抗癌治疗和放射增敏的药物靶点。
Radiotherapy combined with chemotherapy is the treatment of choice for glioblastoma and locally advanced lung cancer, but radioresistance of these two types of cancer remains a significant therapeutic hindrance. To identify molecular target(s) for radiosensitization, we screened a siRNA library targeting all protein kinases and E3 ubiquitin ligases in the human genome and identified TRAF2 (TNF Receptor-associated factor 2). Silencing of TRAF2 using siRNA caused a significant growth suppression of glioblastoma U251 cells and moderately sensitized these radioresistant cells to radiation. Overexpression of a RING deleted dominant negative TRAF2 mutant, also conferred radiosensitivity; whereas over-expression of wild type TRAF2 significantly protected cells from radiation-induced killing. Likewise, siRNA silencing of TRAF2 in radioresistant lung cancer H1299 cells caused growth suppression and radiosensitization, whereas overexpression of wild type TRAF2 enhanced radioresistance in a RING ligase-dependent manner. Moreover, siRNA silencing of TRAF2 in UM-SCC-1 head and neck cancer cells also conferred radiosensitization. Further support for the role of TRAF2 in cancer comes from the observations that TRAF2 is overexpressed in both lung adenocarcinoma tissues and multiple lung cancer cell lines. Importantly, TRAF2 expression was very low in normal bronchial epithelial NL20 cells, and TRAF2 silencing had a minimal effect on NL20 growth and radiation sensitivity. Mechanistically, TRAF2 silencing blocks the activation of the NF-kB signaling pathway, and down-regulates a number of G2/M cell cycle control proteins, resulting in enhanced G2/M arrest, growth suppression, and radiosensitization. Our studies suggest that TRAF2 is an attractive drug target for anti-cancer therapy and for radiosensitization.