DNA损伤应答因子SPOP蛋白调控肿瘤放射敏感性的研究

Radiotherapy is an important therapeutic tool for malignant tumor. The improvement of radiosensitivity in tumor is the primary determinant of radiotherapy. Tumor radiotherapy resistance is intimate correlated to the DNA damage response pathway. SPOP (Speckle-type POZ protein) was originally identified as an autoantigen in the patient with scleroderma by using of immunoscreening approach. SPOP has been shown to mediate the ubiquitylation of nuclear proteins, and plays an important role in tumorigenesis and progression. It is not clear whether SPOP involves in tumor radiotherapy resistance. Our previous work showed the differences of SPOP expression levels between various tumor tissues were related to radiosensitivity. SPOP inhibition sensitized HeLa cells to irradiation and leaded to defects in DNA repair. Therefore, we hypothesize: SPOP regulates tumor radiosensitivity by participating in DNA damage response pathway? Basing on former results, we will use diverse methods, such as RT-RCR, RNA interference, immunoprecipitation and mass spectrometry technology, to investigate how SPOP involves in DNA damage response pathway which includes DNA repair, DNA damage checkpoint and/or apoptosis. Furthermore, we will explore the way to increase tumor radiosensitivity by SPOP inhibition in animal level. This work can expanse the understanding of cellular DNA damage response pathway, and also provide theoretical basis for developing novel molecular targeted radiosensitizer in tumor radiotherapy.

放射治疗是恶性肿瘤的重要治疗手段之一，肿瘤放射抵抗与DNA损伤应答机制密切相关。SPOP蛋白参与多种核蛋白的泛素化修饰和降解，在肿瘤发生发展中扮演着重要角色，但SPOP与肿瘤放射敏感性的关系目前尚不明确。我们前期研究：不同肿瘤组织SPOP表达水平具有差异性，且与肿瘤放射敏感性相关；抑制SPOP表达可增加Hela细胞放射敏感性；SPOP在DNA损伤修复过程中发挥重要作用。因此提出假设：SPOP通过参与DNA损伤应答通路调控肿瘤放射治疗敏感性？本研究拟以前期工作为基础，采用RT-RCR、RNA干扰、免疫共沉淀、质谱分析等技术在肿瘤组织、细胞系及动物水平分别研究SPOP在放射线引起的DNA损伤应答（细胞周期停滞、损伤修复和/或细胞凋亡）中的作用，探讨抑制SPOP表达促肿瘤放射治疗敏感性的疗效及机制。这是对细胞DNA损伤应答机制理论的扩展，也将为肿瘤放射治疗分子靶向增敏剂的开发提供理论基础。

放射治疗是恶性肿瘤的重要治疗手段之一，肿瘤放射抵抗与DNA损伤应答密切相关。SPOP蛋白参与多种核蛋白的泛素化修饰和降解，在肿瘤发生发展中扮演着重要角色。本项目重点阐明了SPOP通过调节DNA损伤应答影响肿瘤细胞的放射敏感性。我们发现SPOP在肺癌细胞系中广泛表达。IR后SPOP在DNA损伤位点定位及表达水平提高。SPOP敲低影响DNA损伤修复、细胞周期及细胞凋亡。此外发现SPOP正向调节DDR蛋白Rad51转录水平的表达，并筛选出DNA损伤后SPOP相关性分子。因此本项目揭示了SPOP在DDR信号通路和肿瘤细胞放射敏感性中的重要作用，将为肿瘤放射治疗分子靶向增敏剂的开发提供理论基础。