Irreversibly Silencing Oncogenic Master-regulator cMyc Using Library-derived Electrophilic Helical Peptides

一种被发现在70%以上癌症的发展中起关键作用的人类基因被称为MYC。该基因编码一种蛋白质（称为cMyc），负责将正常细胞转化为癌细胞，促进癌细胞生长和肿瘤形成。cMyc是一种难以用抗体药物靶向的蛋白质，因为它存在于抗体无法到达的癌细胞细胞核内。cMyc也是一种很难用小分子药物靶向的蛋白质，小分子药物可以进入癌细胞的细胞核，但不能轻易阻断cMyc与其他蛋白质和DNA在大表面积上的相互作用。没有已知的小分子可以阻断cmyc蛋白的相互作用，只有少数非常低效的小分子可以阻断Myc-DNA的相互作用。在这里，我们将开发和测试一种新的治疗方法，从长远来看，可以通过沉默cMyc和杀死表达myc的癌细胞来克服这些问题，而不杀死正常的人类细胞。我们建议筛选细胞内含有氨基酸的肽文库，以找到选择性结合cMyc能力最好的肽。我们已经开发出一种方法，通过添加一种化学“亲电试剂”来加强肽与目标蛋白的结合，这种亲电试剂可以像安全别针一样将肽粘在蛋白质上。优化后的肽将选择性地与cMyc结合而不会脱落。这种方法可以在化学上沉默cMyc，防止它促进癌症。我们的初步数据表明，这种方法是可行的，因为我们发现我们可以不可逆地将肽结合到cMyc上，并阻止其与细胞内存在的蛋白质伴侣的结合，潜在地沉默其功能，并在不杀死正常细胞的情况下导致癌细胞死亡。该提案旨在基于我们强大的概念验证试点数据来优化肽序列：(a)与cMyc蛋白的选择性结合，(b)与cMyc蛋白的紧密和不可逆结合，(c)最大限度地将肽吸收到癌细胞并进一步进入其细胞核，(d)与癌细胞细胞核内的cMyc不可逆结合，(e)诱导一系列表达cMyc的人类癌细胞死亡而不杀死正常细胞。这些努力的成功将引起制药公司和医学研究人员的极大兴趣，他们对cMyc作为癌症的新靶点感到兴奋。我们提出了一种全新的可行的治疗方法来治疗一个非常有前途的新的癌症靶点。开发的技术将有可能转移到与疾病途径有关的其他蛋白质-蛋白质相互作用（PPIs）。

A human gene that has been found to be crucial in the development of over 70% of all cancers is known as MYC. This gene codes for a protein (called cMyc) that is responsible for transforming normal cells to cancer cells and promoting cancer cell growth and tumour formation. cMyc is a difficult protein to target with antibody-based drugs because it exists inside the nucleus of cancer cells where antibodies cannot go. cMyc is also a difficult protein to target with small molecule drugs that can enter the nucleus of cancer cells but cannot readily block the interactions cMyc makes across large surface areas with other proteins and DNA. No small molecules are known to block cMyc-protein interactions, and only a few small molecules of very low potency block Myc-DNA interactions.Here we will develop and test a new approach to generating therapeutics that can, in the long term, overcome these problems by silencing cMyc and kill Myc-expressing cancer cells without killing normal human cells. We propose to screen libraries of amino acid-containing peptides inside cells to find those with the best ability to selectively bind to cMyc. We have developed a method for tightening the binding of peptides to the target protein through adding a chemical 'electrophile' that sticks the peptide to the protein like a safety pin mechanism. Optimised peptides will bind selectively to cMyc and not come off. This approach can chemically silence cMyc and prevent it from promoting cancer. Our preliminary data demonstrates that this approach can work in that we have found that we can irreversibly bind peptides to cMyc and stop its binding to protein partners present inside cells, potentially silencing its functions and causing cancer cell death without killing normal cells.The proposal seeks to build upon our strong proof-of-concept pilot data to optimise the peptide sequences for: (a) selective binding to the protein cMyc, (b) tight and irreversible binding to the protein cMyc, (c) maximum uptake of the peptides into cancer cells and further into their nucleus, (d) irreversible binding to cMyc inside the nucleus of cancer cells, (e) inducing death of a range of cMyc-expressing human cancer cells without killing normal cells. Success in these endeavours will be of exceptional interest to pharmaceutical companies and medical researchers who are becoming excited about cMyc as a new target for cancer. We present an entirely new and viable therapeutic approach to a very promising new cancer target. The technology developed will be potentially transferable to other protein-protein interactions (PPIs) implicated in disease pathways.