An integrated biophysics approach towards realisation of a new class of membrane-active anticancer therapies

众所周知，生物产生自己的抗生素宿主防御肽，这些肽通过破坏细菌膜发挥作用，因为它们的分子组成与宿主有机体自己的细胞不同。其中一些抗菌肽也被认为具有抗癌特性。一种特别有前景的抗癌多肽是巴西黄蜂Paulista Polybia毒素中的Polybia MP1(MP1)。这些多肽的抗癌作用机制与它们的抗菌作用机制相似。最近我们发现，PE和PS两种脂类显著放大了MP1‘S膜的破坏作用，这两种脂类在癌细胞表面的组成比正常组织细胞高得多。因此，MP1是一种很有希望开发新型抗癌药物的候选多肽。这个项目的目的是优化这种多肽的效力和特异性，以产生有希望的化合物，用于进一步的临床开发。通过我们目前对其相互作用机制的了解，以及这种相互作用与分子结构的关系，我们将产生一套由MP1衍生的多肽，其氨基酸组成具有预定的单一变化。这些多肽将被筛选出对具有代表癌症和正常细胞以及癌症和正常细胞系的成分的模型膜的活性。与MP1相比，显示出更强效力或特异性的突变将被结合在第二轮设计的多肽和活性筛选中。这一筛选阶段最有希望的多肽将被用于更详细地描述它们与膜和细胞的相互作用。我们将使用一种新的方法，利用我们可以从日益复杂的系统中获得的不同见解，从具有代表相关细胞关键组成成分的简化脂质混合物的最小膜模型，到从相关细胞提取的膜，再到细胞本身。这将允许从模型膜获得的详细生物物理信息与整个细胞中复杂的生物反应之间史无前例的关联。细胞系的脂质组成也将被表征，特别是对多肽诱导的膜破坏最敏感和最耐受的膜的组成。高灵敏表面分析和光学显微镜技术的应用将提供对多肽-膜相互作用的性质的详细洞察。重要的是，除了抗癌多肽的开发外，这些信息还将有助于深入了解多肽结构、膜组成和相互作用机制之间的关系，这将有助于开发一系列膜活性多肽，包括抗菌肽和细胞穿透肽。我们的目标是在这一项目的后续项目中，通过全面的临床前开发，确定三种最有效的化合物，这些化合物可以通过全面的临床前开发进行首例临床试验。目前还没有针对这些细胞膜的抗癌药物。因此，MP1衍生多肽的成功翻译将标志着抗癌治疗武器库中的一种新的抗癌药物。特别是，我们还将测试这些多肽与现有化疗药物联合使用的前景，并调查任何协同效应。

Organisms are well known to produce their own antibiotic host-defence peptides that act through damaging bacterial membranes due to their different molecular composition compared to the host organism's own cells. Some of these antimicrobial peptides are also known to have anticancer properties. One particularly promising anticancer peptide is polybia MP1 (MP1) from the venom of the Brazilian wasp Paulista Polybia.The mechanistic basis for the anticancer properties of these peptides bears similarities to their antimicrobial mode of action. Recently we showed that MP1's membrane disrupting effects were significantly amplified by two classes of lipid, PE and PS, which are present in much higher composition on the surface of cancer cells than the cells of normal tissue. Therefore, MP1 is a promising candidate peptide for development of a novel anticancer agent. This project will aim to optimise this peptide for potency and specificity to generate promising compounds for further clinical development.Through our current understanding of its interaction mechanism and how this relates to molecular structure, we will generate a set of MP1-derived peptides with predetermined single changes in amino acid composition. These peptides will be screened for activity against model membranes with compositions representative of cancer and normal cells as well as cancer and normal cell lines. Mutations that display enhanced potency or specificity compared to MP1 will be combined in a second round of designed peptides and activity screening. The most promising peptides from this screening phase will be taken forward for more detailed characterisation of their interactions with membranes and cells. We will use a novel approach that takes advantage of the different insights we can gain from systems of increasing complexity from minimal membrane models with simplified lipid mixtures representative of key compositional contents of the relevant cells, to membranes extracted from the relevant cells, to the cells themselves. This will allow unprecedented correlation between the detailed biophysical information obtained from model membranes to the complex biological response in whole cells. The lipid compositions of the cell lines will also be characterised, with particular interest in the compositions of membranes that are most sensitive to and those that are most resistant to peptide-induced membrane disruption.Application of highly sensitive surface analytical and optical microscopy techniques will provide detailed insight into the nature of peptide-membrane interactions. Importantly, beyond development of an anticancer peptide, this information will contribute valuable fundamental insight into the relationship between peptide structure, membrane composition and interaction mechanism that will be of use in the development of a wide range of membrane-active peptides, including antimicrobial peptides and cell penetrating peptides.We aim to identify the three most potent compounds that can be taken forward towards first-in-man clinical trials through full preclinical development in a project that will follow on from this one. No current anticancer drug targets the membrane of these cells. Therefore successful translation of an MP1-derived peptide would signal a new class of anticancer drug in the therapeutic arsenal against cancer. In particular we will also test the peptides' promise for use in combination with existing chemotherapeutics and investigate any synergistic effects.