Cysteine oxidation as a regulator of cancer cell motility and invasion

在发育的重要阶段，细胞通常在组织中移动。然而，在健康个体中调节细胞运动的一些相同过程也有助于癌细胞如何从原发肿瘤转移并扩散到全身。了解细胞运动是如何被调节的，不仅能让我们了解正常的生物学，还能帮助我们更多地了解癌症。这些知识的一个成果是建立正常生物学和癌症之间的联系，这可能有助于提高诊断，并确定可能被癌症治疗阻断的潜在靶点。细胞中的蛋白质通常通过附着小的化学修饰而被修饰，这些修饰的范围可能从氨基酸的小链到像氧一样小的分子。这些修饰可能会改变蛋白质功能的许多方面，例如它的活性，它的位置甚至蛋白质的稳定性。在半胱氨酸氨基酸残基上添加氧已被发现是某些特定蛋白质的重要调节因子。然而，研究半胱氨酸-氧修饰在技术上是困难的，因为工具不是直接使用的，而且一旦蛋白质从其自然环境中移除，它可能会在半胱氨酸残基上自发氧化。因此，蛋白质氧化领域并没有像其他类型的蛋白质修饰那样迅速发展。我们发现细胞运动的过程增加了半胱氨酸残基上的蛋白质氧化，并确定了200多种经历这种修饰的蛋白质。通过研究一种特殊的蛋白质，我们发现它的氧化在迁移过程中增加，特别是两种半胱氨酸的氧化阻断了它的正常活性。当这种蛋白的一种不能被氧化的版本在细胞中表达时，细胞粘附在表面和直线移动的能力就会降低，这表明通过氧化阻止蛋白质的功能对细胞有效移动很重要。在这个提议中，我们将在许多癌细胞系中鉴定由半胱氨酸氧化修饰的蛋白质，并将确定这种修饰如何改变选定子集的蛋白质功能。我们还将确定导致这种修饰的活性氧产生的机制，以及一种称为Rac1的特定蛋白质对这一过程的贡献。最后，通过对移植肿瘤细胞的成像，我们将在活组织中建立细胞侵袭和蛋白靶氧修饰之间的联系。我们还将研究阻断Rac1活性是如何影响组织侵袭和活性氧生成的，Rac1活性已被提出作为一个可能的抗癌药物靶点，以确定这一机制是否有助于这些化合物的治疗效果。通过这些研究，我们的目标是发现通过组织调节细胞运动的基础生物学的新方面。这些知识将与癌症生物学直接相关，并可能有助于建立改善诊断或确定未来癌症药物靶点的联系。

Cells normally move through tissues during important stages of development. However, some of the same processes that regulate cell movement in a healthy individual also contribute to how cancer cells move away from a primary tumour and spread throughout the body. Understanding how cell movement is regulated not only informs us about normal biology but also helps us to know more about cancer. A product of this knowledge is establishing links between normal biology and cancer that could help to improve diagnosis and to identify potential targets that might be blocked by cancer therapies.Proteins in cells are often modified by the attachment of small chemical modifications, which may range from small chains of amino acids to molecules as small as oxygen. These modifications may change many aspects of a protein's function, such as how active it is, where it is located or even the protein stability. The addition of oxygen to cysteine amino acid residues has previously been found to be an important regulator of some specific proteins. However, studying cysteine-oxygen modification is technically difficult, both because the tools are not straight-forward to use and because once a protein is removed from its natural context then it may be spontaneously oxidized on cysteine residues. As a result, the field of protein oxidation has not progressed as rapidly as other types of protein modification.We have found that the process of cell movement increases protein oxidation on cysteine residues, and have identified over 200 proteins that undergo this modification. By studying one protein in particular, we found that its oxidation was increased during migration and that the oxidation of two cysteines in particular blocked its normal activity. When a version of this protein that could not be oxidised was expressed in cells, the ability of cells to stick to a surface and to move in a straight line were reduced, indicating that blocking the protein function through oxidation is important for how cells move efficiently.In this proposal, we will identify proteins modified by cysteine oxidation in a number of cancer cell lines, and will determine how this modification changes protein function for a selected subset. We will also identify the mechanism for the generation of the reactive oxygen production that causes this modification, and the contribution of a specific protein called Rac1 to this process. Finally, by imaging transplanted tumour cells, we will establish the link between cell invasion and oxygen modification of protein targets in live tissue. We will also examine how blocking Rac1 activity, which has been proposed as a possible anti-cancer drug target, affects tissue invasion and reactive oxygen generation to determine whether this mechanism contributes to the therapeutic effects of these compounds.Through these studies, we aim to discover novel aspects of the fundamental biology regulating cell movement through tissues. This knowledge will have direct relevance to cancer biology, and may help to establish links that improve diagnosis or identify future cancer drug targets.