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

描述（由申请人提供）：钛（IV）化合物是具有广谱效应的优秀抗癌候选药物。由于这些化合物的溶液不稳定性和惰性Ti（IV）氧化物的产生，配方问题阻碍了它们向药物市场的过渡。一些生物分子，即血清蛋白转铁蛋白（Tf），通过提供稳定的配合位点，使Ti（IV）能够在体内运输，从而规避了这一问题。本文旨在利用Tf金属结合位点及其细胞内金属运输来开发基于Ti（IV）的抗癌化合物的仿生药物设计策略。新的配体将通过包含两个重要的结构成分来促进钛（IV）的抗癌特性。一种成分是一种生物活性肽，能够选择性地和受体介导地转运到癌细胞中。生物活性肽P物质（SP）和转铁蛋白受体1结合肽是Ti（IV）配体肽组分的优秀候选者，因为它们的主要受体在许多癌细胞中相对于正常细胞过度表达。这些受体在相同的癌细胞系中没有过度表达，因此这项研究将展示如何使用生物活性肽来微调选定癌症的靶向。该肽组分将与具有金属配位偏好的Tf模拟金属结合片段偶联，可以操纵其在癌细胞中释放Ti（IV）。N，N'-二（邻羟基苄基）乙二胺-N，N'-二乙酸（HBED）和去铁氧铁金属结合配体适合于此目的。HBED与Ti（IV）的结合具有高亲和力，但与Fe（III）的结合具有更强的亲和力。这些配体具有稳定地将Ti（IV）转运到细胞内，然后释放Ti（IV）以换取Fe（III）的潜力。通过消耗癌细胞中对金属离子有较高需求的Fe(III)，这些配体可以与Ti（IV）协同作用，触发细胞死亡。将对Ti（IV）肽偶联化合物进行一系列细胞毒性机制研究，以检验肽、金属结合部分和Ti（IV）离子的作用。将研究Fe（III）取代Ti（IV）的动力学，以确定其生理可行性。将进行结构活性关系研究，以阐明最大化Ti（IV）细胞毒性的肽和金属结合部分成分的结构特性。此外，通过金属组学和代谢组学质谱研究的结合，将深入了解细胞内Ti（IV）靶点和Ti（IV）抑制的代谢途径。这些机理研究将为合理设计Ti（IV）化合物提供优化依据。

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.