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    Abstract:
    Abstract Lack of effective treatments for aggressive breast cancer is still a major global health problem. We have previously reported that photodynamic therapy using methylene blue as photosensitizer (MB-PDT) massively kills metastatic human breast cancer, marginally affecting healthy cells. In this study, we aimed to unveil the molecular mechanisms behind MB-PDT effectiveness and specificity towards tumor cells. Through lipidomics and biochemical approaches, we demonstrated that MB-PDT efficiency and specificity rely on polyunsaturated fatty acid-enriched membranes and on the better capacity to deal with photo-oxidative damage displayed by non-tumorigenic cells. We found out that, in tumorigenic cells, lysosome membrane permeabilization is accompanied by ferroptosis and/or necroptosis. Our results also pointed at a cross-talk between lysosome-dependent cell death (LDCD) and necroptosis induction after photo-oxidation, and contributed to broaden the understanding of MB-PDT-induced mechanisms and specificity in breast cancer cells. Therefore, we demonstrated that efficient approaches could be designed on the basis of lipid composition and metabolic features for hard-to-treat cancers. The results further reinforce MB-PDT as a therapeutic strategy for highly aggressive human breast cancer cells.
    Genetically programmed cell death is a universal and fundamental cellular process in multicellular organisms. Apoptosis and necroptosis, two common forms of programmed cell death, play vital roles in maintenance of homeostasis in metazoans. Dysfunction of the regulatory machinery of these processes can lead to carcinogenesis or autoimmune diseases. Inappropriate death of essential cells can lead to organ dysfunction or even death; ischemia-reperfusion injury and neurodegenerative disorders are examples of this. Recently, novel forms of non-apoptotic programmed cell death have been identified. Although these forms of cell death play significant roles in both physiological and pathological conditions, the detailed molecular mechanisms underlying them are still poorly understood. Here, we discuss progress in using small molecules to dissect three forms of non-apoptotic programmed cell death: necroptosis, ferroptosis, and pyroptosis.
    Pyroptosis
    Apoptotic cell death
    Citations (59)
    Autophagy is a degradation mechanism involved in quality and quantity control of cytoplasmic proteins and organelles,regarded as a programmed cell death juxtaposed with apoptosis and necrosis.Unravelled correlations between autophagy,apoptosis and necrosis,however,suggest that autophagy may be a manager of programme cell death,and determine whether cell death occurs and selection of death pathways in response to stress.Revealing molecular mechanism of autophagy contributes to understand these seemingly contradictory views.Elucidation of autophagy′s role in programmed cell death has important practical significance for treating tumor.
    Executor
    Organelle
    Citations (1)
    Abstract Cell death contributes to the maintenance of homeostasis, but mounting evidence has confirmed the involvement of programmed cell death in some diseases. The concept of programmed cell death, which was coined several decades ago to refer to apoptosis, now also encompasses necroptosis, a newly characterized cell death program. Research on programmed cell death has become essential for the development of some new therapies. To study cell death signaling and its molecular mechanisms, new biochemical and fluorogenic approaches have been devised. Here, we first provide an overview of programmed cell death modes and the importance of dynamic cell death studies. Next, we focus on both apoptotic and necroptotic signaling and their mechanisms by providing a systematic review of all the methods and approaches that have been used. We emphasize the contribution of advanced approaches based on fluorescent probes, reporters, and Förster resonance energy transfer (FRET)‐based biosensors for studying programmed cell death. Because apoptosis and necroptosis signaling pathways share some effectors molecules, we discuss how these new tools could be used to discriminate between apoptosis and necroptosis. We also describe how we developed specific FRET‐based biosensors for detecting necroptosis. Finally, we touch on how dynamic measurement of biomolecules in living models will play a role in personalized prognosis and therapy.
    Citations (12)
    Abstract Autophagy is a major intracellular degradation system that derives its degradative abilities from the lysosome. The most well-studied form of autophagy is macroautophagy, which delivers cytoplasmic material to lysosomes via the double-membraned autophagosome. Other forms of autophagy, namely chaperone-mediated autophagy and microautophagy, occur directly on the lysosome. Besides providing the means for degradation, lysosomes are also involved in autophagy regulation and can become substrates of autophagy when damaged. During autophagy, they exhibit notable changes, including increased acidification, enhanced enzymatic activity, and perinuclear localization. Despite their importance to autophagy, details on autophagy-specific regulation of lysosomes remain relatively scarce. This review aims to provide a summary of current understanding on the behaviour of lysosomes during autophagy and outline unexplored areas of autophagy-specific lysosome research.
    Autophagosome
    Citations (585)
    This chapter contains sections titled: Introduction Types of Programmed Cell Death Type 1 Programmed Cell Death Type 2 Programmed Cell Death Type 3 Programmed Cell Death Other Types of Programmed Cell Death The Contribution of Autophagy to Programmed Cell Death Death Processes That Require atg Genes The Combined Activation of Autophagy and Apoptosis during Programmed Cell Death Emerging Relationships between Apoptosis and Autophagy Autophagy and Cell Survival Autophagy is Cytoprotective during Nutrient Depletion in Mammalian Cells Autophagy and Neuroprotection Cytoprotective Roles of Autophagy in the Response to Infectious Pathogens Autophagy and Organism Survival Concluding Remarks Acknowledgments References
    Citations (0)
    Programmed cell death (PCD) occurs in several forms including apoptosis and necroptosis. Apoptosis is executed by the activation of caspases, while necroptosis is dependent on the receptor interacting protein kinase 3 (RIPK3). Precise control of cell death is crucial for tissue homeostasis. Indeed, necroptosis is triggered by caspase inhibition to ensure cell death. Here we identified a previously uncharacterized cell death pathway regulated by TAK1, which is unexpectedly provoked by inhibition of caspase activity and necroptosis cascades. Ablation of TAK1 triggers spontaneous death in macrophages. Simultaneous inhibition of caspases and RIPK3 did not completely restore cell viability. Previous studies demonstrated that loss of TAK1 in fibroblasts causes TNF-induced apoptosis and that additional inhibition of caspase leads to necroptotic cell death. However, we surprisingly found that caspase and RIPK3 inhibitions do not completely suppress cell death in Tak1-deficient cells. Mechanistically, the execution of the third cell death pathway in Tak1-deficient macrophages and fibroblasts were mediated by RIPK1-dependent rapid accumulation of reactive oxygen species (ROS). Conversely, activation of RIPK1 was sufficient to induce cell death. Therefore, loss of TAK1 elicits noncanonical cell death which is mediated by RIPK1-induced oxidative stress upon caspase and necroptosis inhibition to further ensure induction of cell death.
    RIPK1
    NLRP1
    Caspase 8
    Citations (10)