ABSTRACT
Malignant cells frequently demonstrate an oncogenic-driven reliance on glycolytic metabolism to support their highly proliferative nature. Overexpression of pyruvate dehydrogenase kinase (PDK) may promote this unique metabolic signature of tumor cells by inhibiting mitochondrial function. PDKs function to phosphorylate and inhibit pyruvate dehydrogenase (PDH) activity. Silencing of PDK expression has previously been shown to restore mitochondrial function and reduce tumor cell proliferation. High dose Vitamin B1, or thiamine, possesses antitumor properties related to its capacity to reduce PDH phosphorylation and promote its enzymatic activity, presumably through PDK inhibition. Though a promising nutraceutical approach for cancer therapy, thiamine's low bioavailability may limit clinical effectiveness. Here, we have demonstrated exploiting the commercially available lipophilic thiamine analogs sulbutiamine and benfotiamine increases thiamine's anti-cancer effect in vitro. Determined by crystal violet proliferation assays, both sulbutiamine and benfotiamine reduced thiamine's millimolar IC50 value to micromolar equivalents. HPLC analysis revealed that sulbutiamine and benfotiamine significantly increased intracellular thiamine and TPP concentrations in vitro, corresponding with reduced levels of PDH phosphorylation. Through an ex vitro kinase screen, thiamine's activated cofactor form thiamine pyrophosphate (TPP) was found to inhibit the function of multiple PDK isoforms. Attempts to maximize intracellular TPP by exploiting thiamine homeostasis gene expression resulted in enhanced apoptosis in tumor cells. Based on our in vitro evaluations, we conclude that TPP serves as the active species mediating thiamine's inhibitory effect on tumor cell proliferation. Pharmacologic administration of benfotiamine, but not sulbutiamine, reduced tumor growth in a subcutaneous xenograft mouse model. It remains unclear if benfotiamine's effects in vivo are associated with PDK inhibition or through an alternative mechanism of action. Future work will aim to define the action of lipophilic thiamine mimetics in vivo in order to translate their clinical usefulness as anticancer strategies.
Subject(s)
Antineoplastic Agents/pharmacology , Dietary Supplements , Thiamine/analogs & derivatives , Thiamine/pharmacology , Animals , Apoptosis/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Confidence Intervals , Female , Humans , Inhibitory Concentration 50 , Intracellular Space/metabolism , Mice, Nude , Pyruvate Dehydrogenase Acetyl-Transferring Kinase/metabolism , Pyruvate Dehydrogenase Complex/metabolism , Thiamine/chemistry , Thiamine Pyrophosphate/metabolismABSTRACT
Diabetic retinopathy (DR) is a microvascular disease of the retina and the leading cause of visual disability in diabetic patients. Genetic factors have shown to play a pivotal role in DR onset, and several candidate genes have been associated with its progression. A literature search was performed to identify the genes known to be associated with DR through linkage analysis, candidate gene association, and genome-wide association studies (GWAS). A further literature search was performed to discover their potential connection with various biological pathways. A total of 65 genes were found and several of these genes belong to major signaling pathways known to play a significant role in DR, including systemic inflammation, angiogenesis, and neurogenesis. A comprehensive analysis presented in this review will be helpful in unraveling the role of genetics in the pathogenesis of DR.
Subject(s)
Diabetic Retinopathy/genetics , Genetic Linkage , Genome-Wide Association Study , Humans , Neovascularization, Pathologic , Signal Transduction/geneticsABSTRACT
Vascular inflammation plays a critical role in the pathogenesis of diabetic retinopathy. Recently, Interleukin-6 (IL-6) trans-signaling via soluble IL-6 receptor (sIL-6R) has emerged as a prominent regulator of inflammation in endothelial cells. This study was designed to test the hypothesis that selective inhibition of the IL-6 trans-signaling pathway will attenuate inflammation and subsequent barrier disruption in retinal endothelial cells. Human retinal endothelial cells (HRECs) were exposed to IL-6 and sIL-6R to induce IL-6 trans-signaling and the commercially available compound sgp130Fc (soluble gp-130 fused chimera) was used to selectively inhibit IL-6 trans-signaling. IL-6 trans-signaling activation caused a significant increase in STAT3 phosphorylation, expression of adhesion molecules, ROS production and apoptosis in HRECs whereas a significant decrease in mitochondrial membrane potential and NO production was observed in IL-6 trans-signaling activated cells. These changes were not observed in cells pre-treated with sgp130Fc. IL-6 trans-signaling activation was sufficient to cause barrier disruption in endothelial monolayers and pre-treatment of HRECs with sgp130Fc, maintained endothelial barrier function similar to that of untreated cells. Thus, in conclusion, these results indicate that IL-6 trans-signaling is an important mediator of inflammation, apoptosis and barrier disruptive effects in the retinal endothelial cells and inhibition of the IL-6 trans-signaling pathway using sgp130-Fc attenuates vascular inflammation and endothelial barrier disruption.
Subject(s)
Blood-Retinal Barrier/drug effects , Endothelial Cells/metabolism , Inflammation/prevention & control , Interleukin-6/antagonists & inhibitors , Recombinant Fusion Proteins/pharmacology , Signal Transduction/drug effects , Apoptosis/drug effects , Blotting, Western , Cells, Cultured , Endothelial Cells/pathology , Fluorescent Antibody Technique, Indirect , Humans , Hydrogen Peroxide/metabolism , Interleukin-6/metabolism , Membrane Potential, Mitochondrial , Microscopy, Confocal , Mitochondria/drug effects , Mitochondria/metabolism , Nitric Oxide/metabolism , Phosphorylation , Reactive Oxygen Species/metabolism , Receptors, Interleukin-6/metabolism , Retinitis/prevention & control , STAT3 Transcription Factor/metabolismABSTRACT
PURPOSE: To investigate the adverse and favorable situations experienced by elderly people in chronic health conditions, and the coping strategies. METHODOLOGY: The sample included 18 elderly. The information was collected through interviews with open questions. The "Collective Subject Discourse" technique was used for analysis. RESULTS: The findings demonstrated that death and separation from the family were perceived as the most significant adverse situations, while the favorable situations included the family, wisdom, experience, retirement, and life itself. The coping strategies focused on the problem and the emotion. Emotion-focused coping included: belief in God, maintaining the usual activities, family and significant other support, participation in elderly social groups and rejection of losses related to the aging process. The problem-focused coping consisted of the medical treatment and body care.
Subject(s)
Adaptation, Psychological , Chronic Disease/psychology , Life Change Events , Aged , Aged, 80 and over , Female , Humans , Interviews as Topic , Male , Middle AgedABSTRACT
Investigar as situações adversas e favoráveis vivenciadas por pessoas idosas em condições crônicas de saúde, e as estratégias de enfrentamento, foi o objetivo deste estudo. A amostra constou de 18 idosos e as informações foram obtidas por entrevistas com questões abertas. Para a análise, utilizou-se a técnica do Discurso do Sujeito Coletivo. Os resultados mostraram que a morte e a separação de familiares foram vistas como as mais significantes situações adversas. As situações favoráveis incluíram a família, sabedoria, experiência, aposentadoria e a vida em si. O enfrentamento se apresentou focalizado no problema e na emoção. O enfrentamento focalizado na emoção se caracterizou pelo sentimento de fé, pelo trabalho, pela busca de ajuda da família e de outras pessoas significantes, pela participação em grupo de idosos e pela rejeição às perdas naturais relacionadas ao envelhecimento. O enfrentamento, focalizado no problema, foi representado pela busca do atendimento médico e cuidado do corpo, numa tentativa de minimizar os problemas
