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Staurosporine induces necroptotic cell death under caspase-compromised conditions in U937 cells
(2012)
For a long time necrosis was thought to be an uncontrolled process but evidences recently have revealed that necrosis can also occur in a regulated manner. Necroptosis, a type of programmed necrosis is defined as a death receptor-initiated process under caspase-compromised conditions. The process requires the kinase activity of receptor-interacting protein kinase 1 and 3 (RIPK1 and RIPK3) and mixed lineage kinase domain-like protein (MLKL), as a substrate of RIPK3. The further downstream events remain elusive. We applied known inhibitors to characterize the contributing enzymes in necroptosis and their effect on cell viability and different cellular functions were detected mainly by flow cytometry. Here we report that staurosporine, the classical inducer of intrinsic apoptotic pathway can induce necroptosis under caspase-compromised conditions in U937 cell line. This process could be hampered at least partially by the RIPK1 inhibitor necrotstin-1 and by the heat shock protein 90 kDa inhibitor geldanamycin. Moreover both the staurosporine-triggered and the classical death ligand-induced necroptotic pathway can be effectively arrested by a lysosomal enzyme inhibitor CA-074-OMe and the recently discovered MLKL inhibitor necrosulfonamide. We also confirmed that the enzymatic role of poly(ADP-ribose)polymerase (PARP) is dispensable in necroptosis but it contributes to membrane disruption in secondary necrosis. In conclusion, we identified a novel way of necroptosis induction that can facilitate our understanding of the molecular mechanisms of necroptosis. Our results shed light on alternative application of staurosporine, as a possible anticancer therapeutic agent. Furthermore, we showed that the CA-074-OMe has a target in the signaling pathway leading to necroptosis. Finally, we could differentiate necroptotic and secondary necrotic processes based on participation of PARP enzyme.
Background: Pulmonary nocardiosis (PN) is an uncommon but potentially life-threatening infection. Most of our knowledge is derived from case reports or smaller case series. Recently, increasing PN incidence rates have been reported. We aim to describe the clinical course of and risk factors for PN in four Western European countries and to estimate population-based annual hospitalization rates.
Methods: Retrospective evaluation (1995 to 2011) of the clinical course of and risk factors for PN in patients from 11 hospitals in four European countries (Germany, Austria, Switzerland and The Netherlands). Calculation of population-based estimates of hospitalization rates of PN in Germany (2005 to 2011) using official German nationwide diagnosis-related groups (DRG) hospital statistics.
Results: Forty-three patients fulfilled stringent criteria for proven (n = 8) and probable (n = 35) PN; seven with extrapulmonary dissemination. Within the 43 patients, major PN risk factors were immunocompromising (83.7%) and/or pulmonary (58.1%; in 27.9% as only comorbidity) comorbidities. Median duration of PN targeted therapy was 12 weeks. Distinguished patterns of resistance were observed (imipenem susceptibility: N. farcinica 33.3%; N. asteroides 66.7%). Overall mortality rate was 18.9%; in disseminated PN 50%. Over time, annual PN hospitalization rates remained unchanged at around 0.04/100′000 with the highest rate among men aged 75–84 years (0.24/100′000).
Conclusion: PN is rare, but potentially life-threatening, and mainly affects immunocompromised elder males. Overall annual hospitalization rates remained stable between 2005 and 2011.