P22phox调节低分化非小细胞肺癌细胞对TRAIL凋亡敏感性研究

TNF-related apoptosis-inducing ligand, also called as TRAIL, is a novel agent for tumor-targeted therapy, which can selectively induce tumor cell apoptosis but with low toxicity to normal cells. However, non-small-cell lung carcinoma cell (NSCLC) confers resistance to TRAIL-induced apoptosis, meanwhile, the approaches used to accurately evaluate the apoptotic sensitivity of NSCLC cells to TRAIL in clinic is currently lacking. In previous investigation, we found a positive correlation between the differentiation state and TRAIL apoptotic sensitivity in NSCLC. Because of low expression level of TRAIL receptor DR4, the poorly-differentiated NSCLC confers strong resistance to TRAIL-induced apoptosis. Further analysis revealed that DR4 expression level in NSCLC is tightly regulated by the core subunit of NADP/NADPH oxidase, p22 phox, which can inhibit DR4 degradation at post-translational level. On the basis of this result, we identified a small molecule FM301 that can activate p22 phox expression, which subsequently increased DR4 expression and reversed apoptotic resistance of poorly-differentiated NSCLC against TRAIL. Moreover, FM301 is low toxic to normal cells. In this study, we will further confirm the correlation between differentiation state of NSCLC, p22phox expression and TRAIL apoptotic sensitivity; explore the biological mechanisms for the suppressed DR4 degradation by p22 phox; unveil the signaling pathways underlying FM301-induced p22 phox expression in NSCLC; and moreover, evaluate the therapeutic value of TRAIL+FM301 against poorly-differentiated NSCLC. The result of this study will provide theoretical basis and novel strategy for the targeted therapy of NSCLC.

TRAIL是新型靶向抗肿瘤药物，但非小细胞肺癌(NSCLC)呈现对TRAIL不同程度的凋亡耐受性，且临床可用于对NSCLC进行TRAIL敏感性分型指标缺乏。我们发现NSCLC分化状态与TRAIL凋亡敏感性相关，低分化NSCLC由于低表达TRAIL受体DR4，耐受TRAIL诱导细胞凋亡；而DR4表达水平与NADP/NADPH氧化酶调节亚基p22phox表达正相关，且p22phox能抑制DR4蛋白质降解。小分子化合物FM301通过激活p22phox表达上调DR4，逆转低分化NSCLC对TRAIL的凋亡耐受。本研究将进一步明确NSCLC分化状态、p22phox表达、TRAIL凋亡敏感性之间的相关性；探索p22phox抑制DR4泛素化降解机制；阐明FM301诱导p22phox表达的信号传导途径；评价TRAIL+FM301对低分化NSCLC的治疗价值；为NSCLC的靶向性治疗提供更多理论依据与策略。

抗肿瘤靶向药物TRAIL对肿瘤细胞具有良好的选择性，但非小细胞肺癌细胞（NSCLC）对TRAIL耐受。为了寻找该耐受机制，并对其进行有效逆转，我们发现TRAIL的功能型受体DR4在不同临床分化程度的NSCLC中的表达存在差异。DR4表达水平随NSCLC 临床分化程度的升高而升高，且与超氧阴离子生成的p22phox的表达水平正相关。体外实验表明p22phox与DR4存在相互作用，而且p22phox能够通过影响DR4与其E3连接酶Cbl的相互作用抑制DR4的泛素化降解。通过药物筛选发现FK506能够激活DR4蛋白的表达，增加NSCLC对TRAIL诱导凋亡的敏感性。该增敏作用依赖于其对p22phox的上调。有意思的FK506联合TRAIL 还能激活DR4 mRNA的转录，进而对TRAIL诱导的凋亡进行进一步放大，且该放大效应依赖于超氧阴离子的参与。该研究为开发TRAIL抗肿瘤增敏剂提供了研究方法与理论依据。