Oxaliplatin complexes with carnosine and its derivatives: in vitro cytotoxicity, mass spectrometric and computational studies with a focus on complex fragmentation

The complexation of the Pt-based anti-cancer drug oxaliplatin (OxPt) with biological ligands other than DNA is believed to be a major cellular sink for the drug reducing its therapeutic potential and acting as a potential cause of toxicity. In this paper, an in vitro study on hepatocellular carcinoma HepG2 cells suggests that the naturally abundant cytoplasmic dipeptide ligand β-alanyl-L-histidine dipeptide (carnosine) may inhibit the cytotoxic action of OxPt most likely through the formation of complexes that are less cytotoxic than OxPt alone. Evidence is provided to suggest that pre-exposure of HepG2 cells to elevated levels of carnosine appears to have a lasting effect on reducing the cytotoxicity of OxPt even after the removal of the carnosine. This effect, however, is shown to be under kinetic control as its magnitude was shown not to vary significantly with the level of carnosine exposure within the concentration range used in this study. Various mass spectrometry techniques employing electrospray ionization and chip nanospray were employed to study the interaction of oxaliplatin with carnosine as well as two of its derivatives being β-alanyl-N-methylhistidine (anserine) and N-Acetylcarnosine (NAC). Evidence of complexation between OxPt and each of the three ligands examined is presented. Most species observed were unambiguously assigned and compared to their theoretical isotopic patterns. Common fragmentation products due to the collisionally-activated protonated complexes of each of the ligands examined with OxPt, [M + OxPt + H]+ where M= carnosine, anserine or NAC were reported. Density functional calculations at B3LYP/LANL2DZ were used to obtain structural information and relative free energies of different isomers of the observed precursor [Carnosine + OxPt + H]+ both in the gas phase and in solution as well as to probe its fragmentation, highlighting plausible fragmentation mechanisms that account for all the experimental results.Data are presented to show several binding modes between electron rich sites such as N and O centers of carnosine and the Pt metal of OxPt. Calculations were also employed to obtain proton affinities and free energies of key reactions. The proton affinities of carnosine, Anserine and NAC at 298 K were calculated to be 254.4, 255.9 and 250.2 kcal mol-1 respectively. To the best of our knowledge the proton affinities of anserine and N-acetyl-carnosine are the first reported values in the literature

Mouse Cofactor of BRCA1 (Cobra1) Is Required for Early Embryogenesis

Negative elongation factor (NELF) is a four-subunit protein complex conserved from Drosophila to humans. In vitro biochemical and tissue culture-based studies have demonstrated an important role of NELF in controlling RNA polymerase II (Pol II) pausing in transcription. However, the physiological significance of NELF function is not clear due to the lack of any genetic systems for studying NELF.Here we show that disruption of the mouse B subunit of NELF (NELF-B), also known as cofactor of BRCA1 (Cobra1), causes inner cell mass (ICM) deficiency and embryonic lethality at the time of implantation. Consistent with the phenotype of the Cobra1 knockout (KO) embryos, knockdown of Cobra1 in mouse embryonic stem cells (ESCs) reduces the efficiency of colony formation and increases spontaneous differentiation. Cobra1-depleted ESCs maintain normal levels of Oct4, Nanog, and Sox2, master regulators of pluripotency in ESCs. However, knockdown of Cobra1 leads to precocious expression of developmental regulators including lymphoid enhancer-binding factor 1 (Lef1). Chromatin immunoprecipitation (ChIP) indicates that Cobra1 binds to the Lef1 promoter and modulates the abundance of promoter-bound RNA polymerase.Cobra1 is essential for early embryogenesis. Our findings also indicate that Cobra1 helps maintain the undifferentiated state of mESCs by preventing unscheduled expression of developmental genes

LIF-Dependent Signaling: New Pieces in the Lego

LIF, a member of the IL6 family of cytokine, displays pleiotropic effects on various cell types and organs. Its critical role in stem cell models (e.g.: murine ES, human mesenchymal cells) and its essential non redundant function during the implantation process of embryos, in eutherian mammals, put this cytokine at the core of many studies aiming to understand its mechanisms of action, which could benefit to medical applications. In addition, its conservation upon evolution raised the challenging question concerning the function of LIF in species in which there is no implantation. We present the recent knowledge about the established and potential functions of LIF in different stem cell models, (embryonic, hematopoietic, mesenchymal, muscle, neural stem cells and iPSC). We will also discuss EVO-DEVO aspects of this multifaceted cytokine

Reliability-based prediction of chloride ingress and reinforcement corrosion of aging concrete bridge decks

This paper presents a probabilistic approach for predicting the chloride contamination of concrete and reinforcing steel corrosion, which takes into account the uncertainty associated with the analytical models of chloride transport, corrosion initiation, as well as damage accumulation, material properties, structural dimensions, and applied environmental and mechanical loads. The proposed approach is illustrated on an aging reinforced concrete bridge deck that has been exposed to chlorides from deicing salts for forty years. An extensive non-destructive and destructive evaluation of the corrosion-damaged deck was undertaken. The field survey data showed a considerable level of variability in all parameters measured with coefficients of variation ranging from 34% for the concrete cover depth to 86% for the diffusion coefficient. The distributions of the chloride concentration at the level of the top reinforcement mat and the time for its corrosion initiation were generated using Monte Carlo Simulation. The simulated results were very close to the field data, which illustrates the prediction capabilities of probabilistic methods as opposed to deterministic methods.Le rapport pr\ue9sente une approche probabiliste pour la pr\ue9diction de la contamination par les chlorures du b\ue9ton et de la corrosion des armatures en acier, approche qui tient compte de l'incertitude associ\ue9e aux mod\ue8les analytiques de transport des chlorures, de formation de la corrosion ainsi qu'\ue0 l'accumulation des dommages, aux propri\ue9t\ue9s des mat\ue9riaux, aux dimensions des structures et aux charges environnementales et m\ue9caniques appliqu\ue9es. On applique l'approche propos\ue9e \ue0 un tablier de pont vieillissant en b\ue9ton arm\ue9 qui a \ue9t\ue9 expos\ue9 aux chlorures contenus dans les sels de d\ue9gla\ue7age pendant quarante ans. On a entrepris une \ue9valuation compl\ue8te destructive et non destructive du tablier corrod\ue9. Les donn\ue9es recueillies au cours de l'\ue9tude sur le terrain ont indiqu\ue9 un degr\ue9 important de variabilit\ue9 pour tous les param\ue8tres mesur\ue9s, les coefficients de variation allant de 34 % pour l'\ue9paisseur d'enrobage de b\ue9ton \ue0 86 %, pour le coefficient de diffusion. La distribution des concentrations de chlorures au niveau du treillis sup\ue9rieur d'armature et le moment o\uf9 la corrosion a commenc\ue9 \ue0 se former ont \ue9t\ue9 g\ue9n\ue9r\ue9s \ue0 l'aide de la m\ue9thode Monte Carlo. Les r\ue9sultats simul\ue9s \ue9taient tr\ue8s proches des donn\ue9es obtenues sur le terrain, ce qui montre bien la sup\ue9riorit\ue9 des m\ue9thodes de pr\ue9diction probabilistes sur les m\ue9thodes d\ue9terministes.Peer reviewed: NoNRC publication: Ye

Vulnerability and protection of Canada's infrastructure

Peer reviewed: YesNRC publication: Ye

Evaluating the Potential Anticancer Properties of Salvia triloba in Human-Osteosarcoma U2OS Cell Line and Ovarian Adenocarcinoma SKOV3 Cell Line

Salvia triloba (S. triloba) is an herb inherently linked to traditional medicine systems in the Eastern Mediterranean region. There is minimal experimental evidence however, regarding the anticancer effects of S. triloba in both osteosarcoma and ovarian cancer. In this study, we investigated the effects of crude (macerated) S. triloba ethanol and acetone leaf extracts on viability, migratory ability, and the expression of genes regulating these activities in U2OS and SKOV3 cells using MTT assay, scratch-wound healing/trans-well migration assay, and RT-qPCR respectively. MTT assay results indicated that the acetone extract significantly reduced both U2OS and SKOV3 cell viability with half-maximal inhibitory concentrations (IC50) of 54.51 ± 1.10 µg/mL and 75.96 ± 1.0237 µg/mL respectively; these concentrations further displayed negligible hemolytic activity. The combination of acetone extract (19 µg/mL) and paclitaxel (0.787 µg/mL) displayed synergy and reduced SKOV3 cell viability by over 90%. Additionally, the trans-well migration assay illustrated that the acetone extract (IC50) inhibited both U2OS and SKOV3 cell migration by more than 50%. Moreover, S. triloba acetone extract significantly downregulated the steady-state mRNA expression of key genes involved in driving select cancer hallmarks. Four fractions were generated from the acetone extract by thin layer chromatography (TLC), and the obtained retention factors (Rf) (ranging from 0.2 to 0.8) suggested a mixture of high and moderately polar compounds whose bioactivities require further investigation. In addition, FTIR measurements of the extract revealed peaks corresponding to OH, aliphatic CH, and ester groups suggesting the presence of phenolic compounds, terpenes, and polysaccharides. Altogether, these results suggest that S. triloba possesses potential therapeutic compounds that inhibit cell proliferation and migration, and modulate several genes involved in osteosarcoma and ovarian carcinoma progression