Delivery of a bacterial inhibitor of NF-kB to colon tumors

描述(由申请人提供)： 建议研究的意义。结直肠癌在美国是一种常见的癌症，每年在全球范围内造成近100万人死亡。迫切需要改进的化疗药物和化学预防药物。活化B细胞核因子-轻链增强子(NF-β)转录因子复合体是细胞存活和肿瘤发生的关键促进剂。核因子-β活化与结直肠癌的发生发展密切相关。核因子-βB抑制剂是理想的，并可能防止细胞进展为结肠癌。我们已经发现了一种细菌蛋白，它可以选择性地改变肠道细胞中核因子-βB的转录活性。这种蛋白NleH1由大肠杆菌O157：H7表达，与新发现的核糖体蛋白S3(RPS3)结合并抑制其功能。RPS3通常指导核因子-βB复合体向特定基因启动子的招募。NleH1通过减少RPS3的核丰度来抑制随后的宿主转录输出。RPS3还在DNA修复和调节肿瘤转移中发挥重要作用。重要的是，RPS3在结直肠癌中也表达上调。我们对一种具有天然肠道细胞亲和性的细菌蛋白的研究可能会对未来结直肠化疗的发展具有重要的作用。我们的长期目标是表征NleH1蛋白，并利用我们获得的信息设计治疗结直肠癌的新疗法，其中NleH1和RPS3实际上普遍存在调控错误。这一特殊应用的目的是测试将NleH1转移到结肠癌细胞系将抑制细胞增殖的假设。其具体目的是：1)量化NleH1降低结肠癌细胞系中RPS3核丰度的程度；2)量化NleH1抑制RPS3转录活性和降低结肠癌细胞系细胞增殖的程度。这项拟议的研究具有重要意义和创新性，因为它将评估转位细菌效应蛋白在抑制与癌症发展相关的宿主转录活动方面的效用。这些研究将对结肠癌的治疗产生重要的积极影响，因为它们将为未来优化NleH1针对结肠癌细胞的特异性靶向的机制研究以及对NleH1负责抑制RPS3和NF-βB的区域的功能解剖奠定基础。

DESCRIPTION (provided by applicant): Significance of the proposed research. Colorectal cancer is a common form of cancer in the United States and is responsible for nearly a million deaths each year worldwide. Improved chemotherapeutics and chemopreventive agents are urgently needed. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-?B) transcription factor complex is a key promoter of cell survival and tumorigenesis. NF-?B activation is strongly correlated with the development of colorectal cancer. NF-?B inhibitors are desired and are likely to prevent cellular progression to colon cancer. We have discovered a bacterial protein that selectively alters the transcriptional activity of NF-?B in intestinal cells. This protein, NleH1, expressed by Escherichia coli O157:H7, binds to and inhibits the function of a newly identified subunit of NF-?B, the ribosomal protein S3 (RPS3). RPS3 normally guides the recruitment of the NF-?B complex to specific gene promoters. NleH1 functions by reducing the nuclear abundance of RPS3 to dampen subsequent host transcriptional outputs. RPS3 also plays an important role in DNA repair and regulates tumor metastases. Importantly, RPS3 is also upregulated in colorectal cancers. Our proposed studies of a bacterial protein with a natural intestinal cell tropism that binds and inhibits the activities of both RPS3 and NF-?B are likely to have significant utility in the future development of colorectal chemotherapeutics Our long-term goal is to characterize the NleH1 protein and use the information we obtain to design novel therapies for colorectal cancers, in which NF-?B and RPS3 are virtually universally misregulated. The objective of this particular application is to test the hypothesis that delivering NleH1 to colon cancer cell lines will inhibit cellular proliferation. The specific aims are to: 1) quantify the extent to which NleH1 reduces the nuclear abundance of RPS3 in colon cancer cell lines and 2) quantify the extent to which NleH1 inhibits the transcriptional activities of RPS3 and reduces cellular proliferation of colon cancer cell lines. The proposed research is significant and innovative because it will evaluate the utility of a translocated bacterial effector protein in inhibiting host transcriptional activities associated with cancer development. These studies will have a significant positive impact on colon cancer therapeutics, as they will form the basis both for future mechanistic studies in which the specific targeting of NleH1 to colon cancer cells is optimized and also for functional dissection of the region of NleH1 responsible for inhibiting RPS3 and NF-?B.