Therapeutic Targeting Mitochondrial C1 Metabolism

摘要 代谢重编程是癌症的一个重要标志。代谢途径的改变 在恶性肿瘤中，一碳（C1）代谢尤其显著。丝氨酸的3-碳是主要的C1 在胞质溶胶中嘌呤和胸苷酸从头合成的供体，以及 丝氨酸和甘氨酸的合成发生在线粒体中。线粒体C1途径也产生 还原当量，是ATP的重要来源。线粒体C1途径的第一种酶， 丝氨酸羟甲基转移酶（SHMT）2是一种致癌驱动因子，在大量的肿瘤细胞中被上调。 癌的越来越多的证据表明，SHMT 2可能是一个独立的预后因素， 癌症的治疗靶点。我们发现了新的5-取代吡咯并[3，2-d]嘧啶化合物AGF 291， AGF 347和AGF 359。在它们被质子偶联叶酸转运蛋白（PCFT）内化后， 化合物抑制SHMT 2的线粒体C1代谢，并直接次级抑制细胞溶质 嘌呤（DNP）从头生物合成的靶点（5-氨基咪唑-4-甲酰胺核苷酸 甲酰转移酶和甘氨酰胺核糖核苷酸甲酰转移酶）和SHMT 1。我们的化合物抑制 上皮性卵巢癌、非小细胞肺癌、结肠直肠癌和胰腺癌的增殖 (PaC)细胞，表明其作为广谱抗肿瘤剂的潜力。AGF 347在以下方面表现出显著性： 体内抗肿瘤功效，具有针对早期和后期PaC异种移植物的完全缓解潜力 模型我们认为，我们的新化合物为治疗癌症提供了一种全新的方法。我们的目标 是优化我们的先导结构，通过PCFT和抑制线粒体和细胞溶质的肿瘤靶向 C1代谢在中等剂量下具有最小毒性。我们将使用PaC作为疾病原型， 我们的新型多靶点抑制剂的开发。在目标1中，我们将合成多达100种基于 对先导化合物的作用，以优化肿瘤的摄取，并抑制SHMT 2和胞质途径，包括 DNP生物合成。在目标2中，我们将测试来自目标1的类似物的抗肿瘤效力， PaC细胞系，肿瘤选择性和质膜和线粒体药物转运，药物代谢， 抑制SHMT 2和胞质途径，包括DNP生物合成。我们将衡量下游影响 对mTOR信号传导、线粒体呼吸、谷胱甘肽池和活性氧的影响。在目标3中， 将通过以下方法评价来自目的1和2的化合物的药代动力学、耐受性和体内抗肿瘤活性： 使用人PaC细胞系异种移植物和PDX模型以及使用KPC小鼠PaC模型的毒性/功效试验。 我们的先导类似物是“一流的”，我们提出的研究将提供最佳的优化化合物， 选择性肿瘤靶向和抗肿瘤功效的平衡，由抑制SHMT 2和 下游合成代谢途径。我们期待开发用于IND的SHMT 2/DNP靶向化合物 根据我们的研究提交和临床试验。

ABSTRACT Metabolic reprogramming is an important hallmark of cancer. Of the altered metabolic pathways associated with malignancy, one-carbon (C1) metabolism is particularly notable. The 3-carbon of serine is the major C1 donor for de novo synthesis of purines and thymidylate in the cytosol, and the primary catabolic pathway for serine and synthesis of glycine occurs in the mitochondria. The mitochondrial C1 pathway also generates reducing equivalents and is an important source of ATP. The first enzyme of the mitochondrial C1 pathway, serine hydroxymethyltransferase (SHMT) 2, is an oncodriver which is upregulated in a substantial number of cancers. Growing evidence suggests that SHMT2 could be an independent prognostic factor and an important therapeutic target for cancer. We discovered novel 5-substituted pyrrolo[3,2-d]pyrimidine compounds AGF291, AGF347, and AGF359. Following their internalization by the proton-coupled folate transporter (PCFT), these compounds inhibit mitochondrial C1 metabolism at SHMT2, with direct secondary inhibitions of cytosolic targets in de novo purine (DNP) biosynthesis (at 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase and glycinamide ribonucleotide formyltransferase) and SHMT1. Our compounds inhibit proliferation of epithelial ovarian cancer, non-small cell lung cancer, colorectal cancer, and pancreatic cancer (PaC) cells, suggesting their potential as broad-spectrum anti-tumor agents. AGF347 exhibited significant in vivo antitumor efficacy with potential for complete responses against both early and upstage PaC xenograft models. We posit that our novel compounds offer an entirely new approach for treating cancer. Our objective is to optimize our lead structures for tumor targeting via PCFT and inhibition of mitochondrial and cytosolic C1 metabolism at modest doses with minimal toxicity. We will use PaC as a disease prototype for further development of our novel multi-targeted inhibitors. In Aim 1, we will synthesize up to 100 compounds based on lead compounds to optimize uptake by tumors, and inhibition of SHMT2 and cytosolic pathways including DNP biosynthesis. In Aim 2, we will test analogs from Aim 1 for antitumor potencies toward clinically relevant PaC cell lines, tumor selectivity and plasma membrane and mitochondrial drug transport, drug metabolism, and inhibition of SHMT2 and cytosolic pathways including DNP biosynthesis. We will measure downstream impacts on mTOR signaling, mitochondrial respiration, glutathione pools, and reactive oxygen species. In Aim 3, we will evaluate pharmacokinetics, tolerability, and in vivo antitumor activities of compounds from Aims 1 and 2 by toxicity/efficacy trials with human PaC cell line xenograft and PDX models, and with the KPC mouse PaC model. Our lead analogs are “first-in-class” and our proposed studies will afford optimized compounds with the best balance of selective tumor targeting and anti-tumor efficacy, resulting from inhibition of SHMT2 and downstream anabolic pathways. We anticipate developing SHMT2/DNP-targeted compounds for IND submission and clinical trials based on our studies.