Associations between childhood height and morphologically different variants of melanoma in adulthood

AbstractAim of the studyMelanoma subtypes have different aetiological characteristics. Child height is positively associated with adult melanoma; however, a clarification of associations with specific melanoma variants is necessary for an improved understanding of risk factors underlying the histologic entities. This study investigated associations between childhood height and future development of cutaneous melanoma variants.MethodA cohort study of 316,193 individuals from the Copenhagen School Health Records Register, with measured heights at ages 7–13 years who were born from 1930 to 1989. Melanoma cases were identified via linkage to the national Danish Cancer Registry and subdivided into subtypes. Cox proportional hazards regressions were performed.ResultsA total of 2223 cases of melanoma distributed as 60% superficial spreading melanoma (SSM), 27.5% melanoma not otherwise specified (NOS), 8.5% nodular melanoma (NM), and 2% lentigo maligna melanoma (LMM). The remaining rare melanoma forms were not analysed. Childhood height was positively and significantly associated with SSM, melanoma NOS, and NM, but not LMM, in adulthood. Per height z-score at age 13 years, the hazard ratios were 1.20 (95% confidence intervals [CI]: 1.13–1.27) for SSM, 1.19 (95% CI: 1.09–1.29) for melanoma NOS, and 1.21 (95% CI: 1.04–1.41) for NM. Further, growth patterns were linked to the melanoma variants with persistently tall children having an increased risk of developing SSM, melanoma NOS, or NM.ConclusionChildhood height is positively associated with the majority of the melanoma variants. These results suggest that the underlying processes contributing to childhood height and growth patterns interconnect early-life events with the predisposition to melanomagenesis in adulthood

High resolution respirometry analysis of polyethylenimine-mediated mitochondrial energy crisis and cellular stress:mitochondrial proton leak and inhibition of the electron transport system

AbstractPolyethylenimines (PEIs) are highly efficient non-viral transfectants, but can induce cell death through poorly understood necrotic and apoptotic processes as well as autophagy. Through high resolution respirometry studies in H1299 cells we demonstrate that the 25kDa branched polyethylenimine (25k-PEI-B), in a concentration and time-dependent manner, facilitates mitochondrial proton leak and inhibits the electron transport system. These events were associated with gradual reduction of the mitochondrial membrane potential and mitochondrial ATP synthesis. The intracellular ATP levels further declined as a consequence of PEI-mediated plasma membrane damage and subsequent ATP leakage to the extracellular medium. Studies with freshly isolated mouse liver mitochondria corroborated with bioenergetic findings and demonstrated parallel polycation concentration- and time-dependent changes in state 2 and state 4o oxygen flux as well as lowered ADP phosphorylation (state 3) and mitochondrial ATP synthesis. Polycation-mediated reduction of electron transport system activity was further demonstrated in ‘broken mitochondria’ (freeze-thawed mitochondrial preparations). Moreover, by using both high-resolution respirometry and spectrophotometry analysis of cytochrome c oxidase activity we were able to identify complex IV (cytochrome c oxidase) as a likely specific site of PEI mediated inhibition within the electron transport system. Unraveling the mechanisms of PEI-mediated mitochondrial energy crisis is central for combinatorial design of safer polymeric non-viral gene delivery systems

Polyethylenimine architecture-dependent metabolic imprints and perturbation of cellular redox homeostasis

AbstractPolyethylenimines (PEIs) are among the most efficient polycationic non-viral transfectants. PEI architecture and size not only modulate transfection efficiency, but also cytotoxicity. However, the underlying mechanisms of PEI-induced multifaceted cell damage and death are largely unknown. Here, we demonstrate that the central mechanisms of PEI architecture- and size-dependent perturbations of integrated cellular metabolomics involve destabilization of plasma membrane and mitochondrial membranes with consequences on mitochondrial oxidative phosphorylation (OXPHOS), glycolytic flux and redox homeostasis that ultimately modulate cell death. In comparison to linear PEI, the branched architectures induced greater plasma membrane destabilization and were more detrimental to glycolytic activity and OXPHOS capacity as well as being a more potent inhibitor of the cytochrome c oxidase. Accordingly, the branched architectures caused a greater lactate dehydrogenase (LDH) and ATP depletion, activated AMP kinase (AMPK) and disturbed redox homeostasis through diminished availability of nicotinamide adenine dinucleotide phosphate (NADPH), reduced antioxidant capacity of glutathione (GSH) and increased burden of reactive oxygen species (ROS). The differences in metabolic and redox imprints were further reflected in the transfection performance of the polycations, but co-treatment with the GSH precursor N-acetyl-cysteine (NAC) counteracted redox dysregulation and increased the number of viable transfected cells. Integrated biomembrane integrity and metabolomic analysis provides a rapid approach for mechanistic understanding of multifactorial polycation-mediated cytotoxicity, and could form the basis for combinatorial throughput platforms for improved design and selection of safer polymeric vectors