Development of Peptide-Conjugate Biomimics for Targeted Ti(IV)-Based Anticancer D

说明(申请人提供)：钛(IV)化合物是极好的抗癌候选药物，具有广泛的效果。由于这些化合物的溶液不稳定和产生惰性的钛(IV)氧化物物种而导致的配方问题阻碍了它们向药品市场的过渡。一些生物分子，即血清蛋白转铁蛋白(Tf)，通过提供稳定的配位位点使钛(IV)能够在体内运输，从而绕过了这个问题。本研究旨在利用Tf金属结合部位及其细胞内金属转运来开发钛(IV)类抗癌化合物的仿生药物设计策略。通过含有两个重要的结构组分，将合成一种新的配体，以促进钛(IV)的抗癌性能。一种成分是生物活性多肽，能够选择性地和受体介导的转运进入癌细胞。生物活性多肽P物质(SP)和转铁蛋白受体1结合多肽是钛(IV)配体的良好候选多肽成分，因为它们的初级受体在许多癌细胞中相对于正常细胞过表达。这些受体在相同的癌细胞系中不会过度表达，因此这项研究将展示生物活性多肽如何用于微调针对选定癌症的靶向。多肽成分将结合到一个类似于Tf的金属结合部分，具有金属配位偏好，可以在癌细胞中操纵钛(IV)的释放。N，N‘-二(邻羟基苄基)乙二胺-N，N’-二乙酸乙二胺(HBED)和去铁基金属结合配体适合于此目的。HBED以高亲和力结合Ti(IV)，而以更强的亲和力结合Fe(III)，Deferasirox也是如此。该配体有可能稳定地将钛(IV)输送到细胞内，然后释放钛(IV)以换取Fe(III)。通过消耗癌细胞中对金属离子要求较高的Fe(III)，配体可以与Ti(IV)协同作用，触发细胞死亡。我们将对钛(IV)多肽共轭化合物进行一系列的细胞毒性机理研究，以考察该多肽、金属结合部分和钛(IV)离子的贡献。将研究Fe(III)置换Ti(IV)的动力学，以确定其生理可行性。将进行结构活性相关性研究，以阐明使钛(IV)的细胞毒性最大化的多肽和金属结合部分的结构性质。此外，通过金属组学和代谢组学的结合研究，将深入了解细胞内的钛(IV)靶点和被钛(IV)抑制的代谢途径。这些机理研究将为优化设计合理的钛(IV)化合物提供依据。

DESCRIPTION (provided by applicant): Titanium(IV) compounds are excellent anticancer drug candidates with a broad spectrum of effect. Formulation issues due to the solution instability of these compounds and the generation of inert Ti(IV) oxide species have hindered their transition to the drug market. Several biomolecules, namely the serum protein transferrin (Tf), circumvent this problem by providing stable coordination sites that enable Ti(IV) to be transported in the body. The proposal herein seeks to exploit the Tf metal binding site and its intracellular metal transport in the development of a biomimetic drug design strategy for Ti(IV)-based anticancer compounds. Novel ligands will be synthesized specific to facilitating the anticancer properties of Ti(IV) by containing two important structural components. One component is a bioactive peptide to enable selective and receptor-mediated transport into cancer cells. The bioactive peptides substance P (SP) and transferrin receptor 1 binding peptides are excellent candidates for the peptide component of the Ti(IV) ligands because their primary receptors are overexpressed in many cancer cells relative to normal cells. These receptors are not overexpressed in the same cancer cell lines and thus this study will show how bioactive peptides can be used to fine-tune targeting of select cancers. The peptide component will be conjugated to a Tf mimicking metal binding moiety with a metal coordination preference that can be manipulated for Ti(IV) release in cancer cells. The N,N'-di(o-hydroxybenzyl) ethylenediamine-N,N'-diacetic acid (HBED) and deferasirox metal binding ligands are suitable for this purpose. HBED binds Ti(IV) with a high affinity but binds Fe(III) with an even stronger affinity and the same is expected of deferasirox. The ligands have the potential to stably transport Ti(IV) into cells and then release Ti(IV) in exchange for Fe(III). By depleting cancer cells of Fe(III), which have a higher requirement for the metal ion, the ligands can work in synergism with Ti(IV) to trigger cell death. A series of cytotoxicity mechanistic studies of the Ti(IV) peptide-conjugate compounds will be performed to examine the contributions of the peptide, the metal binding moiety, and the Ti(IV) ion. The kinetics of Ti(IV) displacement by Fe(III) will be investigated to determine its physiological feasibility. Structure activity relatioship studies will be performed to elucidate the structural properties of both the peptide and metal binding moiety components that maximize the cytotoxicity of Ti(IV). In addition, insight into intracellular Ti(IV) target sites and metabolic pathways inhibited by Ti(IV) will be garnered through a combination of metallomics and metabolomics mass spectrometry studies. These mechanistic studies will afford optimization of the rationally designed Ti(IV) compounds.