The removal of functionally dispensable, infected or potentially neoplastic cells is driven by programmed cell death (PCD) pathways, highlighting their important roles in homeostasis, host defence against pathogens, cancer and a range of other pathologies. Several types of PCD pathways have been described, including apoptosis, necroptosis and pyroptosis; they employ distinct molecular and cellular processes and differ in their outcomes, such as the capacity to trigger inflammatory responses. Recent genetic and biochemical studies have revealed remarkable flexibility in the use of these PCD pathways and indicate a considerable degree of plasticity in their molecular regulation; for example, despite having a primary role in inducing pyroptosis, inflammatory caspases can also induce apoptosis, and conversely, apoptotic stimuli can trigger pyroptosis. Intriguingly, this flexibility is most pronounced in cellular responses to infection, while apoptosis is the dominant cell death process through which organisms prevent the development of cancer. In this Review, we summarize the mechanisms of the different types of PCD and describe the physiological and pathological processes that engage crosstalk between these pathways, focusing on infections and cancer. We discuss the intriguing notion that the different types of PCD could be seen as a single, coordinated cell death system, in which the individual pathways are highly interconnected and can flexibly compensate for one another.

程序性细胞死亡（PCD）途径推动了功能性可分配，感染或潜在赘生性细胞的清除，突出了它们在体内平衡，宿主抵抗病原体，癌症和其他一系列病理过程中的重要作用。已经描述了几种类型的PCD途径，包括细胞凋亡，坏死性坏死和发烧。它们采用不同的分子和细胞过程，其结局也不同，例如引发炎症反应的能力。最近的遗传和生化研究表明，使用这些PCD途径具有显着的灵活性，并表明它们在分子调控方面具有可塑性。例如，尽管炎症半胱天冬酶尽管在诱导细胞凋亡中起主要作用，但它也可以诱导细胞凋亡，相反，凋亡刺激可以引发细胞凋亡。有趣的是，这种灵活性在细胞对感染的反应中最为明显，而凋亡是主要的细胞死亡过程，生物体通过该过程阻止了癌症的发展。在本综述中，我们总结了不同类型PCD的机制，并描述了涉及这些途径之间串扰的生理和病理过程，重点是感染和癌症。我们讨论了一个有趣的概念，即不同类型的PCD可以看作是一个单一的，协调的细胞死亡系统，在该系统中，各个途径高度相互联系，可以灵活地相互补偿。我们总结了不同类型PCD的机制，并描述了涉及这些途径之间串扰的生理和病理过程，重点是感染和癌症。我们讨论了一个有趣的概念，即不同类型的PCD可以看作是一个单一的，协调的细胞死亡系统，在该系统中，各个途径高度相互联系，可以灵活地相互补偿。我们总结了不同类型PCD的机制，并描述了涉及这些途径之间串扰的生理和病理过程，重点是感染和癌症。我们讨论了一个有趣的概念，即不同类型的PCD可以看作是一个单一的，协调的细胞死亡系统，在该系统中，各个途径高度相互联系，可以灵活地相互补偿。