SUMO特异性蛋白酶SENP1介导的Sp1去SUMO化修饰异常在Nano-Co诱导细胞恶性转化中的作用

With the growth of nanotechnology, a large number of nanomaterials will be developed and produced as new formulations with diverse surface properties. Therefore,the population exposure to nanoparticles is growing, and the potential health impact, especially potential carcinogenic effects of these new products cannot be ignored. Here we chose Nano-Co as a model of metal nanoparticles to investigate its carcinogenesis and the potential underlying mechanisms. Previous studies suggest that some metal nanoparticles may have genotoxic and carcinogenic effects, however, the mechanism is still unclear. Our and other previous studies showed that exposure to Nano-Co caused oxidative stress, which may further result in cell malignant transformation and tumor formation in rat. Our preliminary data demonstrated that SP1 was up-regulated through Nano-Co-induced SENP1 overexpression in Nano-Co-transformed cells, which was further confirmed by co-immunoprecipitation. Therefore, we hypothesize that SENP1-mediated Sp1 desumoylation may play an important role in Nano-Co induced cell malignant transformation. To test our hypothesis, we will first investigate whether SENP1 will mediate desumoylation of Sp1 in Nano-Co-transformed human bronchial epithelial BEAS-2B cells by determining the transactivation activity and protein stability of Sp1, the transcriptional activities of downstream genes, and the proliferation, colony formation, cell cycle progression and apoptosis in Nano-Co-transformed cells. Then we will investigate the effects of oxidative stress induced by Nano-Co on the SENP1- mediated Sp1 desumoylation.We expect that our results will reveal the role of SENP1 in Sp1 desumoylation in Nano-Co-induced malignant transformation, and elucidate the potential molecular mechanisms involved in Nano-Co-induced carcinogenesis. Successful completion of this project will lead to a better understanding of the mechanisms by which metal nanoparticles induce carcinogenesis.

研究表明：Nano-Co可刺激细胞产生过多的ROS,诱导细胞恶性转化和动物肿瘤形成,但其潜在致癌机制尚未阐明。本项目前期研究发现：Nano-Co诱导细胞恶性转化中高表达的SENP1促进Sp1表达上调，免疫共沉淀显示二者存在相互作用。因此，我们提出SENP1介导的Sp1去SUMO化修饰异常可能在Nano-Co诱导细胞恶性转化中具有重要作用的假说。拟利用低剂量Nano-Co诱导人支气管上皮细胞恶性转化的模型，研究SENP1介导的Sp1去SUMO化修饰作用，观察SENP1表达失调对Sp1转录活性、蛋白稳定性、下游靶基因转录活化及对转化细胞生长和凋亡的影响，探讨Nano-Co诱导的氧化应激对SENP1介导的Sp1去SUMO化修饰的调节作用。研究结果将揭示SENP1介导的Sp1去SUMO化修饰异常在细胞恶性转化中的重要作用，阐明Nano-Co的潜在致癌作用。这将有助于了解纳米材料基因毒性和致癌性。

金属钴纳米颗粒（Cobalt nanoparticles，Nano-Co）广泛应用于硬质合金、电化学传感器、医学成像、药物投递、肿瘤热疗等领域。随着规模化生产和纳米产品的普及，人群的职业接触和环境暴露的机会明显增加，对人体健康和环境可能产生各种潜在危害，Nano-Co的生物毒性和潜在致癌性亟待研究和阐明。. 本项目在前期研究的基础上，1）采用低剂量Nano-Co慢性染毒BEAS-2B细胞20周，建立Nano-Co诱导细胞恶性转化的生物学模型，结合体内、外实验研究Nano-Co的致癌毒性作用，结果显示：Nano-Co慢性染毒可诱导BEAS-2B细胞软琼脂克隆形成，促进细胞增殖、增强细胞体外迁移和侵袭能力；诱导细胞氧化应激并促进细胞DNA链断裂及DNA氧化损伤。Nano-Co慢性染毒可诱发gpt转基因小鼠DNA氧化损伤、gpt突变频率升高。上述结果表明低剂量Nano-Co慢性染毒可引起细胞DNA损伤，增强基因组不稳定性。2）结合基因干扰、细胞转染等方法，研究发现：慢性染毒细胞中SUMO特异性蛋白酶1（SENP1)和Sp1的转录及蛋白表达水平上调，SENP1可调节Sp1蛋白表达；验证了SENP1可去SUMO 化修饰Sp1并增强Sp1蛋白稳定性，并发现转化细胞内SENP1与Sp1蛋白相互作用增强。干扰SENP1可抑制Nano-Co转化细胞增殖和克隆形成，出现细胞周期S期阻滞；并抑制转化细胞体外迁移、侵袭及其相关蛋白的表达。上述研究结果明确了SENP1介导的Sp1去SUMO化修饰异常在Nano-Co诱导细胞恶性转化中的作用，为Nano-Co 潜在致癌作用评价和致癌机制研究提供了科学依据。