Glucosamine suppresses proliferation of human prostate carcinoma DU145 cells through inhibition of STAT3 signaling

Background  

Glucosamine is known as a toxic agent for several malignant cell lines and transplanted tumors with little toxicity to normal host tissues. However, the mechanisms underlying anticancer activity of glucosamine are poorly understood. To study the mechanisms, the human prostate cancer DU145 cells were used for the model.     

The β-catenin HMP-2 functions downstream of Src in parallel with the Wnt pathway in early embryogenesis of C. elegans

The Wnt and Src pathways are widely used signal transduction pathways in development. β-catenin is utilized in both pathways, as a signal transducer and a component of the cadherin cell adhesion complex, respectively. A C. elegans β-catenin HMP-2 is involved in cell adhesion, but its signaling role has been unknown. Here, we report that in early embryogenesis HMP-2 acts as a signaling molecule in the Src signal. During early embryogenesis in C. elegans, the Wnt and Src pathways are redundantly involved in endoderm induction at the four-cell stage and spindle orientation in an ABar blastomere. RNAi experiments demonstrated that HMP-2 functions in the Src pathway, but in parallel with the Wnt pathway in these processes. HMP-2 localized at the cell boundaries and nuclei, and its localization at cell boundaries was negatively regulated by SRC-1. In addition, HMP-2 was Tyr-phosphorylated in a SRC-1-dependent manner in vivo. Taken together, we propose that HMP-2 functions downstream of the Src signaling pathway and contribute to endoderm induction and ABar spindle orientation, in parallel with the Wnt signaling pathway.     

Mitochondrial density contributes to the immune response of macrophages to lipopolysaccharide via the MAPK pathway

We investigated the role of mitochondrial reactive oxygen species (ROS) in the response of macrophages to lipopolysaccharide (LPS) using RAW 264.7 cells and their ρ(o) cells lacking mitochondria. Mitochondrial density, respiratory activity and related proteins in ρ(o) cells were significantly lower than those in RAW cells. LPS rapidly stimulated mitochondrial ROS prior to cytokine secretion, such as TNF-α and IL-6, from RAW 264.7 cells by activating the MAPK pathway, while the response was attenuated in ρ(o) cells. Exposure of ρ(o) cells to H(2)O(2) partially restored the secretion of cytokines induced by LPS. These results suggest that mitochondrial density and/or the respiratory state contribute to intracellular oxidative stress, which is responsible for the stimulation of LPS-induced MAPK signaling to enhance cytokine release from macrophages.     

Cilostazol activates function of bone marrow-derived endothelial progenitor cell for re-endothelialization in a carotid balloon injury model

Background

Cilostazol(CLZ) has been used as a vasodilating anti-platelet drug clinically and demonstrated to inhibit proliferation of smooth muscle cells and effect on endothelial cells. However, the effect of CLZ on re-endothelialization including bone marrow (BM)-derived endothelial progenitor cell (EPC) contribution is unclear. We have investigated the hypothesis that CLZ might accelerate re-endothelialization with EPCs.

Methodology/Principal Findings

Balloon carotid denudation was performed in male Sprague-Dawley rats. CLZ group was given CLZ mixed feed from 2weeks before carotid injury. Control group was fed normal diet. CLZ accelerated re-endothelialization at 2 weeks after surgery and resulted in a significant reduction of neointima formation 4 weeks after surgery compared with that in control group. CLZ also increased the number of circulating EPCs throughout the time course. We examined the contribution of BM-derived EPCs to re-endothelialization by BM transplantation from Tie2/lacZ mice to nude rats. The number of Tie2-regulated X-gal positive cells on injured arterial luminal surface was increased at 2 weeks after surgery in CLZ group compared with that in control group. In vitro, CLZ enhanced proliferation, adhesion and migration activity, and differentiation with mRNA upregulation of adhesion molecule integrin αvβ3, chemokine receptor CXCR4 and growth factor VEGF assessed by real-time RT-PCR in rat BM-derived cultured EPCs. In addition, CLZ markedly increased the expression of SDF-1α that is a ligand of CXCR4 receptor in EPCs, in the media following vascular injury.

Conclusions/Significance

CLZ promotes EPC mobilization from BM and EPC recruitment to sites of arterial injury, and thereby inhibited neointima formation with acceleration of re-endothelialization with EPCs as well as pre-existing endothelial cells in a rat carotid balloon injury model. CLZ could be not only an anti-platelet agent but also a promising tool for endothelial regeneration, which is a key event for preventing atherosclerosis or restenosis after vascular intervention.     

PADI4 and HLA-DRB1 Are Genetic Risks for Radiographic Progression in RA Patients,Independent of ACPA Status: Results from the IORRA Cohort Study

Introduction

Rheumatoid arthritis (RA) is a systemic, chronic inflammatory disease influenced by both genetic and environmental factors, leading to joint destruction and functional impairment. Recently, a large-scaled GWAS meta-analysis using more than 37,000 Japanese samples were conducted and 13 RA susceptibility loci were identified. However, it is not clear whether these loci have significant impact on joint destruction or not. This is the first study focused on the 13 loci to investigate independent genetic risk factors for radiographic progression in the first five years from onset of RA.

Methods

Sharp/van der Heijde score of hands at 5-year disease duration, which represents joint damage, were measured retrospectively and used as an outcome variable in 865 Japanese RA patients. Genetic factors regarded as putative risk factors were RA-susceptible polymorphisms identified by the Japanese GWAS meta-analysis, including HLA-DRB1 (shared epitope, SE), rs2240340 (PADI4), rs2230926 (TNFAIP3), rs3093024 (CCR6), rs11900673 (B3GNT2), rs2867461 (ANXA3), rs657075 (CSF2), rs12529514 (CD83), rs2233434 (NFKBIE), rs10821944 (ARID5B), rs3781913 (PDE2A-ARAP1), rs2841277 (PLD4) and rs2847297 (PTPN2). These putative genetic risk factors were assessed by a stepwise multiple regression analysis adjusted for possible non-genetic risk factors: autoantibody positivity (anti-citrullinated peptide antibody [ACPA] and rheumatoid factor), history of smoking, gender and age at disease onset.

Results

The number of SE alleles (P = 0.002) and risk alleles of peptidyl arginine deiminase type IV gene (PADI4, P = 0.04) had significant impact on progressive joint destruction, as well as following non-genetic factors: ACPA positive (P = 0.0006), female sex (P = 0.006) and younger age of onset (P = 0.02).

Conclusions

In the present study, we found that PADI4 risk allele and HLA-DRB1 shared epitope are independent genetic risks for radiographic progression in Japanese rheumatoid arthritis patients. The results of this study give important knowledge of the risks on progressive joint damage in RA patients.     

The Hydroxyl Radical Generated by an Iron(II)/EDTA/Ascorbate System Preferentially Attacks Tryptophan Residues of the Protein

Iron(II)/EDTA/ascorbate-mediated oxidative damage to specific amino acid residues (tryptophan) of serum albumin was studied. The active species generated by Fe(II)/EDTA/ascorbate preferred to react with tryptophan residues rather than histidine or other amino acids. The observation of preferential damage to tryptophan residues of the protein was fully suported by a model experiment using a tryptophan analogue. The reaction of Fe(II)/EDTA/ascorbate to the protein was significantly suppressed by mannitol and dimethysulfoxide, suggesting the participation of the hydroxyl radical generated via Fenton’s reaction. The result was supported by the hydroxyl radical assay using 2-deoxyribose.     

Cross-talk of NO,superoxide and molecular oxygen,a majesty of aerobic life

Because nitric oxide (NO) reacts with various molecules, such as hemeproteins, superoxide and thiols including glutathione (GSH) and cysteine residues in proteins, biological effects and metabolic fate of this gaseous radical are affected by these reactants. Although the lifetime of NO is short particularly under air atmospheric conditions (where the oxygen tension is unphysiologically high), it increases significantly under physiologically low oxygen concentrations. Because oxygen tensions in human body differ from one tissue to another and change depending on their metabolism, biological activity of NO in various tissues might be affected by local oxygen tensions. To elucidate the role of NO and related radicals in the regulation of circulation and energy metabolism, their effects on arterial resistance and energy metabolism in mitochondria, mammalian cells and enteric bacteria were studied under different oxygen tensions. Kinetic analysis revealed that NO-dependent generation of cGMP in resistance arteries and their relaxation were strongly enhanced by lowering oxygen tensions in the medium. NO reversibly suppressed the respiration and ATP synthesis of isolated mitochondria and intact cells particularly under low oxygen tensions. Kinetic analysis revealed that cross-talk between NO and superoxide generated in and around endothelial cells regulates arterial resistance particularly under physiologically low oxygen tensions. NO also inhibited the respiration and ATP synthesis of E. coli particularly under low oxygen tensions. Because concentrations of NO and H⁺ in gastric juice are high, most ingested bacteria are effectively killed in the stomach. However, the inhibitory effects of NO on the respiration and ATP synthesis of H. pylori are extremely small. Kinetic analysis revealed that H. pylori generates the superoxide radical thereby inhibiting the bactericidal action of NO in gastric juice. Based on such observations, critical roles of the cross-talk of NO, superoxide and molecular oxygen in the regulation of energy metabolism and survival of aerobic and microaerophilic organisms are discussed.     

Oxidative Stress Underlies the Mechanism for Ca2+-induced Permeability Transition of Mitochondria

Recent studies demonstrated that the generation of intracellular reactive oxygen species (ROS) was enhanced prior to the onset of mitochondrial membrane permeability transition (MPT), a critical step for the induction of DNA fragmentation and apoptosis. Although Ca²⁺ induces typical MPT that involves depolarization and swelling of mitochondria and finally releases cytochrome c into cytosol, the mechanism by which ROS induce MPT remains unclear. In the presence of inorganic phosphate, Ca²⁺ increased the oxygen consumption and ROS production by isolated mitochondria as determined by a chemiluminescence (CHL) method using L-012. Ca²⁺ increased the generation of H²O² by some mechanism that was inhibited by cyclosporin A but not by superoxide dismutase (SOD) and trifluoperazine. Ca²⁺ decreased the content of free thiols in adenine nucleotide translocase (ANT) in mitochondrial membranes with concomitant increase in ROS generation. The presence of cyclosporin A, trifluoperazine, or SOD inhibited the Ca²⁺-induced increase of L-012 CHL and decrease in the free thiols of ANT. These results indicate that Ca²⁺ increases the generation of ROS which oxidize the free thiol groups in mitochondrial ANT, thereby inducing MPT to release cytochrome c.     

Macrocarpal C isolated from Eucalyptus globulus inhibits dipeptidyl peptidase 4 in an aggregated form

Dipeptidyl peptidase 4 (DPP-4) inhibitors are used for the treatment of type-2 diabetes mellitus. Various synthetic inhibitors have been developed to date, and plants containing natural DPP-4 inhibitors have also been identified. Here, 13 plant samples were tested for their DPP-4 inhibitory activity. Macrocarpals A–C were isolated from Eucalyptus globulus through activity-guided fractionation and shown to be DPP-4 inhibitors. Of these, macrocarpal C showed the highest inhibitory activity, demonstrating an inhibition curve characterised by a pronounced increase in activity within a narrow concentration range. Evaluation of macrocarpal C solution by turbidity, nuclear magnetic resonance spectroscopy and mass spectrometry indicated its aggregation, which may explain the characteristics of the inhibition curve. These findings will be valuable for further study of potential small molecule DPP-4 inhibitors.