Translational research : the journal of laboratory and clinical medicine
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Telomeres are DNA-protein structures that form a protective cap on chromosome ends. As such, they prevent the natural ends of linear chromosomes from being subjected to DNA repair activities that would result in telomere fusion, degradation, or recombination. Both the DNA and protein components of the telomere are required for this essential function, because insufficient telomeric DNA length, loss of the terminal telomeric DNA structure, or deficiency of key telomere-associated factors may elicit a DNA damage response and result in cellular senescence or apoptosis. ⋯ We provide an overview of basic telomere structure and maintenance. We outline the telomere biology defects observed in dyskeratosis congenita, focusing on recent discoveries in this field. Last, we review the evidence of how telomere biology may impact sporadic aplastic anemia and the risk for various cancers.
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The purpose of this review is to highlight the importance of telomeres, the mechanisms implicated in their maintenance, and their role in the etiology as well as the treatment of human esophageal cancer. We will also discuss the role of telomeres in the maintenance and preservation of genomic integrity, the consequences of telomere dysfunction, and the various factors that may affect telomere health in esophageal tissue predisposing it to oncogenesis. There has been growing evidence that telomeres, which can be affected by various intrinsic and extrinsic factors, contribute to genomic instability, oncogenesis, as well as proliferation of cancer cells. ⋯ This indicates that telomere maintenance mechanisms may potentially be targeted to make esophageal cancer cells static. The rate at which telomeres in healthy cells shorten is determined by a number of intrinsic and extrinsic factors, including those associated with lifestyle. Avoidance of factors that may directly or indirectly injure esophageal tissue including its telomeric and other genomic DNA can not only reduce the risk of development of esophageal cancer but may also have positive impact on overall health and lifespan.
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Telomeres are DNA-protein structures that cap the ends of chromosomes; telomerase is the enzyme that ensures their integrity. Telomere biology has recently been implicated in the pathogenesis of a variety of lung diseases, including idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease/emphysema, and lung cancer. This review highlights recent discoveries pertaining to the role of telomere biology in lung disease.
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Renal proximal tubule transporters can play a key role in excretion, pharmacokinetic interactions, and toxicity of immunosuppressant drugs. Basolateral organic anion transporters (OATs) and apical multidrug resistance-associated proteins (MRPs) contribute to the active tubular uptake and urinary efflux of these drugs, respectively. We studied the interaction of 12 immunosuppressants with OAT1- and OAT3-mediated [(3)H]-methotrexate (MTX) uptake in cells, and adenosine triphosphate-dependent [(3)H]-MTX transport in membrane vesicles isolated from human embryonic kidney 293 cells overexpressing human MRP2 and MRP4. ⋯ Cytarabine and azathioprine had no effect on either transporter. In conclusion, we charted comprehensively the differences in inhibitory action of various immunosuppressive agents against the 4 key renal anion transporters, and we provide evidence that immunosuppressant drugs can modulate OAT1-, OAT3-, MRP2-, and MRP4-mediated transport of MTX to different extents. The data provide a better understanding of renal mechanisms underlying drug-drug interactions and nephrotoxicity concerning combination regimens with these compounds in the clinic.