Leveraging Metalloinsertors for the PET Imaging and Endoradiotherapy of MMR-Deficient Cancers

项目摘要/摘要 DNA修复途径对于维持基因组的完整性至关重要。然而，聚合酶错误和 接触遗传毒性化学物质可能会导致错配修复(MMR)机制的失调， 负责识别和纠正基因组DNA中错配碱基的蛋白质家族。当这件事 机械故障--或完全不存在--单个碱基错配可能会累积，使细胞 容易产生单核苷酸多态(SNPs)，最终导致肿瘤的发生。事实上，上涨了 所有实体肿瘤中有20%被证明是MMR缺陷。最值得注意的是，MMR缺乏症对 在遗传性非息肉病性结直肠癌(HNPCC)的发生发展中起重要作用。过去的二十年 见证了选择性和特异性结合DNA的八面体铑配合物的发展 不匹配。这些化合物，被称为“金属插入物”，已被证明显示出优先的抗 MMR缺陷与MMR熟练表达的结直肠癌细胞体外增殖效应及对肿瘤的抑制作用 结直肠癌小鼠模型的体内生长。 这份F31提案的重点是合成、体外评估和体内验证一个新的家族。 基于错配靶向金属插入物RhPBC的放射性药物。我们首先计划合成非 放射性的Nati-RhPBC，以便于探针的化学和生物学表征。随后，我们 将产生标记有碘放射性同位素的金属插入物的类似物--要么是发射正电子的碘-- 124(124I；T1/2~4.2d)或发射碘-131(131I；T1/2~8.0d)--制造用于PET成像的放射性药物 和内科放射治疗。具体目标1将集中在化学合成和分析 三种化合物(Nati-RhPBC、124I-RhPBC和131I-RhPBC)及其生物学特性和生物活性 两个相同基因的人结直肠癌细胞系中化合物的体外评价 对于他们的MMR熟练(HCT116N)或MMR缺乏(HCT116O)。在特定目标2中，PET成像和 将通过生物分布实验来评估124I-RhPBC作为诊断和治疗药物的体内性能 治疗MMR缺陷型小鼠结直肠癌模型的放射显像剂。最后，《特定目标3》将 以~(131)I-RhPBC作为放射治疗药物的体内评价为中心，使用生物分布研究、剂量学 MMR缺陷型结直肠癌小鼠模型的计算和纵向治疗研究。 我们认为，这个项目既有很高的创新性，又有很强的影响力。据我们所知， DNA错配以前从未成为核成像和治疗的目标，八面体铑 络合物还没有被用作放射性示踪剂的支架。在短期内，这项工作可能会产生一个 该显像剂可作为MMR缺陷肿瘤患者临床治疗的有用工具。在……里面 从长远来看，这项研究还可能产生一种一流的放射治疗方法，可以用来治疗 多种MMR缺陷肿瘤，改善这些恶性肿瘤患者的预后和结局。

PROJECT SUMMARY / ABSTRACT DNA repair pathways are critical for maintaining the integrity of the genome. Yet polymerase errors and exposure to genotoxic chemicals may lead to the dysregulation of the mismatch repair (MMR) machinery, the family of proteins responsible for identifying and correcting mispaired bases in genomic DNA. When this machinery malfunctions - or is absent altogether - single base mismatches can accumulate, making cells prone to the generation of single nucleotide polymorphisms (SNPs) and, eventually, tumorigenesis. Indeed, up to 20% of all solid tumors have been shown to be MMR-deficient. Most notably, MMR-deficiency plays a significant role in the development of hereditary nonpolyposis colorectal cancer (HNPCC). The last twenty years have witnessed the development of octahedral rhodium complexes that selectively and specifically bind DNA mismatches. These compounds, known as ‘metalloinsertors’, have been shown to exhibit preferential anti- proliferative effects in vitro in MMR-deficient vs. MMR-proficient colorectal cancer cells and to inhibit tumor growth in vivo in a murine model of colorectal cancer. This F31 proposal is focused on the synthesis, in vitro evaluation, and in vivo validation of a novel family of radiopharmaceuticals based on the mismatch-targeting metalloinsertor RhPBC. We first plan to synthesize non- radioactive natI-RhPBC to facilitate the chemical and biological characterization of the probe. Subsequently, we will create analogues of the metalloinsertor labeled with radioisotopes of iodine - either positron-emitting iodine- 124 (124I; t1/2 ~ 4.2 d) or ß-emitting iodine-131 (131I; t1/2 ~ 8.0 d) - to create radiopharmaceuticals for PET imaging and endoradiotherapy, respectively. Specific Aim 1 will be focused on the chemical synthesis and analysis of all three compounds (natI-RhPBC, 124I-RhPBC, and 131I-RhPBC) as well as the biological characterization and in vitro evaluation of the compounds in a pair of isogenic human colorectal cancer cell lines that are identical except for their MMR-proficiency (HCT116N) or MMR-deficiency (HCT116O). In Specific Aim 2, PET imaging and biodistribution experiments will be used to evaluate the in vivo performance of 124I-RhPBC as a diagnostic and theranostic imaging agent in a murine model MMR-deficient colorectal cancer. And finally, Specific Aim 3 will be centered on the in vivo evaluation of 131I-RhPBC as a radiotherapeutic using biodistribution studies, dosimetry calculations, and longitudinal therapy studies in a murine models of MMR-deficient colorectal cancer. We contend that this project is both highly innovative and highly impactful. To the best of our knowledge, DNA mismatches have never before been a target for nuclear imaging and therapy, and octahedral rhodium complexes have not been harnessed as scaffolds for radiotracers. In the short term, this work could produce an imaging agent that could be a useful tool in the clinical management of patients with MMR-deficient tumors. In the longer term, this investigation could also yield a first-in-class radiotherapeutic that could be used against a variety of MMR-deficient tumors, improving prognoses and outcomes for patients with these malignancies.