Differential role of RIP1 in Smac mimetic-mediated chemosensitization of neuroblastoma cells

We explored the potential of Smac mimetics, which antagonize Inhibitor of Apoptosis (IAP) proteins, for chemosensitization of neuroblastoma (NB). Here, we report that Smac mimetics, e.g. BV6, prime NB cells for chemotherapeutics including the topoisomerase II inhibitor doxorubicin (DOX) and vinca alkaloids such as Vincristine (VCR), Vinblastine (VBL) and Vinorelbine (VNR). Additionally, BV6 acts in concert with DOX or VCR to suppress long-term clonogenic growth. While BV6 causes rapid downregulation of cellular IAP (cIAP)1 protein and nuclear factor-kappaB (NF-κB) activation, DOX/BV6- or VCR/BV6-induced apoptosis occurs independently of NF-κB or TNFα signaling, since overexpression of dominant-negative IκBα superrepressor or the Tumor Necrosis Factor (TNF)α-blocking antibody Enbrel fail to block cell death. Mechanistic studies reveal that Receptor-interacting protein (RIP)1 is required for DOX/BV6-, but not for VCR/BV6-induced apoptosis, since transient or stable knockdown of RIP1 or the pharmacological RIP1 inhibitor necrostatin-1 significantly reduce apoptosis. By comparison, VCR/BV6-mediated apoptosis critically depends on the mitochondrial pathway. VCR/BV6 cotreatment causes phosphorylation of BCL-2 during mitotic arrest, enhanced activation of BAX and BAK and loss of mitochondrial membrane potential (MMP). Additionally, overexpression of BCL-2 profoundly suppresses VCR/BV6-induced apoptosis. Thus, BV6 sensitizes NB cells to chemotherapy-induced apoptosis via distinct initial signaling mechanisms depending on the chemotherapeutic drug. These findings provide novel mechanistic insights into Smac mimetic-mediated chemosensitization of NB.     

Insight into the complex pathophysiology of sickle cell anaemia and possible treatment

Sickle cell anaemia (SCA) is the consequence of abnormal haemoglobin production due to an inherited point mutation in the β‐globin gene. The resulting haemoglobin tetramer is poorly soluble when deoxygenated, and when this is prolonged, intracellular gelation of sickle haemoglobin occurs, followed by haemoglobin polymerisation. If many cycles of sickling and unsickling occur, the red cell membrane will be disrupted leading to haemolysis and vaso‐occlusive events. Recent studies have also shown that leucocyte adhesion molecules and nitric oxide (NO) depletion are involved in endothelial damage. New insights in SCA pathophysiology and vascular biology have shown that cell‐derived microparticle (MP) generation is also involved in the vaso‐occlusion. Endothelial damage is perpetuated by impaired production or increased consumption of protective modulators such as protein C, protein S and NO. New therapeutic interventions should address these aspects of SCA pathogenesis. To date, the only US‐FDA‐approved therapy to prevent painful vaso‐occulsive episodes is hydroxyurea that reduces haemoglobin polymerisation in sickle cells by increasing the production of foetal haemoglobin and L‐glutamine. However, several new drugs have been tested in the last years in randomised clinical trials. We here report an update on the current status of knowledge on SCA.     

Fokus Neurochirurgische Intensivmedizin 2021/2022

Die Anaesthesiologie -     

Chronic Childhood Stress: Psychometric Properties of the Chronic Stress Questionnaire for Children and Adolescents (CSQ-CA) in Three Independent Samples

Stress in children and adolescents is common and related to many developmental problems. However, most studies have made no distinction between temporary or chronic stress due to the lack of a suitable questionnaire. This study tested the factor structure, reliability and validity of the 17-item self-report Chronic Stress Questionnaire for Children and Adolescents (CSQ-CA) in three samples, that is, 717 adolescents from the general population, 161 adolescents of parents with a severe chronic medical condition (CMC) like multiple sclerosis, and 113 adolescents with healthy parents. Results showed that a one-factor solution provided a reasonable fit overall. Reliability was good (α = .80 to .88). Convergent validity was supported by positive relations between total stress scores and internalizing and externalizing problem behaviors, experience of daily hassles, and maladaptive emotion regulation strategies and negative relations with quality of life, happiness, mindfulness, self-esteem, and coping skills. Adolescents from all samples, who themselves had a light CMC like asthma, showed higher chronic stress levels than those without a CMC. In line, adolescents of parents with a severe CMC reported more chronic stress than those of healthy parents, and adolescents with a chronic illness themselves and a parent with a chronic illness, showed the highest scores across the two family types. Overall, this study presents good psychometric properties of the first available measure of chronic stress in children and adolescents.