G-quadruplexes formed in human oncogene promoters and their drug complexes

产品说明：本申请是对通知编号（NOT-OD-09-058）和通知标题的回应：NIH宣布为竞争性修订申请提供恢复法案资金。G-四链体DNA二级结构是近年来出现的一类新的肿瘤特异性分子靶点。有令人信服的在体外和体内的证据G-四链体结构中形成的基因的启动子区域参与的生长和增殖作为转录调节因子。我们的母基金建议确定四种癌基因c-Myc、bcl-2、VEGF和HIF-1a及其药物复合物的启动子区域中G-四链体的分子结构。虽然DNA G-四链体是非常有前途的新药物靶点，但其作为癌症治疗靶点的潜力的评估取决于对生物学相关G-四链体结构的理解。为此，似乎需要解决一些额外的重要问题，以充分了解启动子Gquadruplex的生物学作用，并评估其作为癌症治疗靶点的潜力，特别是，G-四链体结构的特异性蛋白质相互作用和基因启动子中形成的DNA二级结构的完整分子系统的考虑。因此，我们在本修订申请中建议研究这两个重要的扩展方面。修订申请中的拟议研究将集中在c-Myc启动子上，因为它是研究最广泛的系统。特别地，c-Myc启动子含有高度保守的polyG/polyC NHE III 1，其控制80-90%的c-Myc转录。NHE III 1已被证明是一个沉默元件，DNA G-四链体结构的形成对c-Myc转录沉默至关重要。此外，稳定这种G-四链体构象的化合物已显示出减少c-Myc表达并且是抗肿瘤的。具体而言，我们建议：1）鉴定结合在c-Myc启动子中形成的DNA G-四链体的蛋白质;和2）确定作为c-Myc启动子的沉默元件中的第二靶标的I基序的结构。这两个具体目标是父母补助金的重要扩展。蛋白质的相互作用和功能对于充分理解基因启动子中DNA二级结构的生物学功能至关重要，而G4相互作用蛋白的鉴定是实现这一目标的第一步。通过包括在富含C链中形成的I基序，修订将扩大母公司授权的范围，以涵盖c-Myc启动子中沉默元件的完整分子系统，用于药物靶向。我们的长期目标是使用基于结构的方法来合理设计特异性结合DNA二级结构并调节基因转录的小分子化合物。修订申请将明显加速靶向基因启动子区域形成的DNA二级结构的研究，用于抗癌药物开发。这两个具体目标相互依存程度不高，都很有可能在两年期内完成。 公共卫生相关性：c-Myc是一种重要的癌基因，已被证实为癌症治疗干预的潜在靶点。它在多种肿瘤类型中过表达，并且其过表达与生存预后不良相关。有效调控c-myc基因的表达为肿瘤的治疗提供了希望。该研究为小分子药物调控c-myc基因表达提供了一种新的策略。

DESCRIPTION: This application is in response to the Notice Number (NOT-OD-09-058) and Notice Title: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications. G-quadruplex DNA secondary structures have recently emerged as a new class of cancer-specific molecular targets for anticancer drugs. There is compelling in vitro and in vivo evidence of G-quadruplex structures formed in the promoter regions of genes involved in growth and proliferation as transcriptional regulators. Our parent grant proposed to define the molecular structures of the G-quadruplexes in the promoter regions of the four oncogenes, c-Myc, bcl-2, VEGF, and HIF-1a, and their drug-complex(es). While the DNA G-quadruplexes are very promising new drug targets, the evaluation of their potential as cancer therapeutic targets depends on the understanding of biologically relevant G-quadruplex structures. To that end, it appears that a number of additional important questions need to be addressed in order to fully understand the biological roles of the promoter Gquadruplexes and to evaluate their potential as cancer therapeutic targets, in particular, the specific protein interactions of the G-quadruplex structures and the consideration of the intact molecular system of the DNA secondary structures formed in gene promoters. Thus we propose in this Revision Application to study these two important expanded aspects. The proposed research in the Revision Application will focus on the c-Myc promoter as it is the most extensively studied system. In particular, the c-Myc promoter contains a highly conserved polyG/polyC NHE III1, which controls 80-90% of the c-Myc transcription. The NHE III1 has been shown to be a silencer element and the formation of a DNA G-quadruplex structure is critical for c-Myc transcriptional silencing. Furthermore, compounds that stabilize this G-quadruplex conformation have been shown to reduce c-Myc expression and are antitumorigenic. Specifically, we propose: 1) to identify the protein(s) that bind the DNA G-quadruplex formed in the c-Myc promoter; and 2) to define the structure of the Imotif as a second target in the silencer element of the c-Myc promoter. The two specific aims are important expansions of the parent grant. Protein interactions and functions will be essential to fully understand the biological function of the DNA secondary structures in gene promoters, and the identification of the G4 interactive protein(s) is the first step towards that goal. By including the I-motif formed in the C-rich strand, the revision will expand the scope of the parent grant to the complete molecular system of the silencer element in the c-Myc promoter for drug targeting. Our long-term objective is to use a structure-based approach to rationally design small molecule compounds that specifically bind DNA secondary structures and modulate gene transcription. The Revision Application will clearly accelerate the research on targeting DNA secondary structures formed in the gene promoter regions for anticancer drug development. The two specific aims are not highly inter-dependent and both have a high likelihood of being completed in the two-year period. PUBLIC HEALTH RELEVANCE: c-Myc is an important oncogene and has been validated as potential targets for cancer therapeutic intervention. It is overexpressed in a variety of tumor types and its overexpression has been associated with poor prognosis for survival. Effective modulation of c-myc expression offers promise for the cancer treatment. The proposed research represents a novel new strategy for modulating c-myc gene expression by small molecule drugs.