Towards a predictive and deterministic understanding of transmitotic cell fates during TRAIL-induced cell death signalling

细胞增殖和细胞死亡之间的微妙平衡是许多生理过程的基础，其失调与癌症的发生有关。程序性细胞死亡，如细胞凋亡，可由结合细胞表面死亡受体的配体触发。我们最近发现，细胞周期进程调节了trail诱导的癌细胞凋亡的易感性：有趣的是，大量通过有丝分裂进程的细胞遭受亚致命的凋亡DNA损伤，并最终逃避外源性凋亡。然而，在这种情况下，等基因群体中单个细胞的命运（死亡vs.逃脱/生存）目前还无法预测。目前，在这种情况下，我们缺乏对TRAIL治疗后细胞命运如何以及何时（预）确定的理解。此外，我们目前还不清楚Mcl-1 （Bcl-2家族中赋予传递性细胞凋亡抗性的主要成员）如何在有丝分裂正常进展后降解以重新建立细胞凋亡易感性。我们将通过详细的定量和动力学研究以及系统生物学方法来解决这些重要的开放性问题，利用我们的创新工具来并行监测细胞周期进程和细胞死亡信号。此外，我们将验证在更复杂的细胞生长情况下，包括实验上可控的三维球体和体内环境下，trail诱导的细胞凋亡的传播抗性或逃逸在多大程度上可以观察到。外源性凋亡将由第二代和翻译相关的六美体TRAIL变异触发，增加了研究计划的应用相关性。已经收集了大量非常有希望的数据，支持我们的研究目标。总的来说，我们相信计划中的工作将使我们能够从描述和观察过渡到外部诱导的细胞死亡信号和细胞周期进程相互作用中的细胞命运决策的预测性和确定性理解。我们的工作解决了一个目前很大程度上未被研究但有影响力的话题，这对于理解细胞死亡调控和逃逸的一个关键方面非常相关。

A subtle balance between cell proliferation and cell death is fundamental for many physiological processes and its dysregulation is implicated in the development of cancer. Programmed cell death, such as apoptosis, can be triggered by ligands that bind to cell-surface death receptors. We recently found that cell cycle progression modulates the susceptibility to TRAIL-induced apoptosis in cancer cells: Interestingly, substantial numbers of cells that progress through mitosis suffer sublethal apoptotic DNA damage and ultimately escape from extrinsic apoptosis. However, the fate (death vs. escape/survival) of individual cells within isogenic populations in this scenario currently cannot be predicted. At the present time, we lack an understanding for how and when cell fates are (pre-)determined following TRAIL treatment in this context. Additionally, we currently do not know quantitatively and kinetically how Mcl-1, the major Bcl-2 family member that confers transmitotic apoptosis resistance, is degraded after normal progression through mitosis to re-establish apoptosis susceptibility. We will approach these important open questions by detailed quantitative and kinetic studies and by systems biological approaches, taking advantage of our innovative tools to monitor cell cycle progression and cell death signalling in parallel. In addition, we will validate to which extent transmitotic resistance to or escape from TRAIL-induced apoptosis can be observed in more complex cell growth scenarios, including experimentally well controllable 3D spheroids and in vivo settings. Extrinsic apoptosis will be triggered by a superior 2nd generation and translationally relevant hexameric TRAIL variant, increasing the application relevance of the research programme. Substantial amounts of highly promising data have been collected that support our research objectives. Overall, we are convinced that the planned work will allow us to transition from description and observation towards a predictive and deterministic understanding of cell fate decision making in the interplay of extrinsically induced cell death signalling and cell cycle progression. Our work addresses a currently largely unstudied but impactful topic that is highly relevant for understanding a crucial facet of cell death-regulation and –escape.