Volume 8, Issue 2

MicroRNAs (miRNAs) are non-coding small RNAs that are master regulators of genic expression and consequently of many cellular processes. But their expression is often deregulated in human tumors leading to cancer development. Recently miRNAs were discovered in body fluids (serum, plasma and others) and their levels have often been reported to be altered in patients. Circulating miRNAs became one of the most promising biomarkers in oncology for early diagnosis, prognosis and therapeutic response prediction. Here we describe the origins and roles of miRNAs, and summarize the most recent studies focusing on their usefulness as cancer biomarkers in lung, breast, colon, prostate, ovary cancers and melanoma. Lastly, we describe the main methodologies related to miRNA detection, which should be standardized for their use in clinical practice.

Ionizing radiation (IR) is a ubiquitous component of our environment and an important tool in research and medical treatment. At the same time, IR is a potent genotoxic and epigenotoxic stressor, exposure to which may lead to negative health outcomes. While the genotoxocity is well described and characterized, the epigenetic effects of exposure to IR and their mechanisms remain under-investigated. In this conceptual review, we propose the IR-induced changes to one-carbon metabolism as prerequisites to alterations in the cellular epigenome. We also provide evidence from both experimental and clinical studies describing the interactions between IR and one-carbon metabolism. We further discuss the potential for the manipulation of the one-carbon metabolism in clinical applications for the purpose of normal tissue protection and for increasing the radiosensitivity of cancerous cells.

Selenium is an essential trace element due to its incorporation into selenoproteins with important biological functions. However, at high doses it is toxic. Selenium toxicity is generally attributed to the induction of oxidative stress. However, it has become apparent that the mode of action of seleno-compounds varies, depending on its chemical form and speciation. Recent studies in various eukaryotic systems, in particular the model organism Saccharomyces cerevisiae , provide new insights on the cytotoxic mechanisms of selenomethionine and selenocysteine. This review first summarizes current knowledge on reactive oxygen species (ROS)-induced genotoxicity of inorganic selenium species. Then, we discuss recent advances on our understanding of the molecular mechanisms of selenocysteine and selenomethionine cytotoxicity. We present evidences indicating that both oxidative stress and ROS-independent mechanisms contribute to selenoamino acids cytotoxicity. These latter mechanisms include disruption of protein homeostasis by selenocysteine misincorporation in proteins and/or reaction of selenols with protein thiols.

Classical all α-helical globins are present in all living organisms and are ordered in three lineages: (i) flavohemoglobins and single domain globins, (ii) protoglobins and globin coupled sensors and (iii) truncated hemoglobins, displaying the 3/3 or the 2/2 all α-helical fold. However, over the last two decades, all β-barrel and mixed α-helical-β-barrel heme-proteins displaying heme-based functional properties (e.g. ligand binding, transport and sensing) closely similar to those of all α-helical globins have been reported. Monomeric nitrophorins (NPs) and α 1 -microglobulin (α 1 -m), belonging to the lipocalin superfamily and nitrobindins (Nbs) represent prototypical heme-proteins displaying the all β-barrel and mixed α-helical-β-barrel folds. NPs are confined to the Reduviidae and Cimicidae families of Heteroptera, whereas α 1 -m and Nbs constitute heme-protein families spanning bacteria to Homo sapiens . The structural organization and the reactivity of the stable ferric solvent-exposed heme-Fe atom suggest that NPs and Nbs are devoted to NO transport, storage and sensing, whereas Hs -α 1 -m participates in heme metabolism. Here, the structural and functional properties of NPs and Nbs are reviewed in parallel with those of sperm whale myoglobin, which is generally taken as the prototype of monomeric globins.

Vascular calcification represents the deposition of calcium phosphate salts in the tunica media of the vascular wall. It occurs during aging but is accelerated and pronounced in patients with diabetes mellitus, chronic kidney disease (CKD) and established cardiovascular disease. Due to the loss of elasticity of the vessel wall, vascular calcification might result in left ventricular hypertrophy and compromise coronary perfusion. Accordingly, several studies showed that vascular calcification is associated with increased risk for cardiovascular morbidity and mortality. Accumulating data suggest that microRNAs (miRs) play an important role in vascular calcification. A variety of miRs have been implicated in the development of vascular calcification, whereas others appear to play a protective role. Accordingly, miRs might represent promising targets for the prevention of vascular calcification and its adverse cardiovascular sequelae. However, given the complexity of regulation of this process and the multitude of miRs involved, more research is needed to identify the optimal candidate miRs for targeting.

This report evaluates plasma protein patterns, dialysates and protein analysis of used dialysis membranes from the same patient under hemodialysis in three separate modalities, using high-flux membranes in concentration-driven transport (HD), convection-driven hemofiltration (HF) and combined hemodialfiltration (HDF). The plasma protein changes induced by each of the three dialysis modalities showed small differences in proteins identified towards our previous plasma analyses of chronic kidney disease (CKD) patients. The used dialysate peptide concentrations likewise exhibited small differences among the modalities and varied in the same relative order as the plasma changes, with protein losses in the order HD>HDF>HF. The membrane protein deposits allowed quantification of the relative Hb removal ratios as ~1.7 for HD and ~1.2 for HDF vs. ~1.0 for HF. Hence, plasma protein alterations, dialysate peptide contents and membrane Hb deposits all identify HD as the modality with the most extensive filtration results and exemplifies the accessibility of protein analysis of used membrane filters for evaluation of dialysis efficiencies.