Novel potassium N-[(2S,3R,4R,5R)-2,3,4,5,6-pentahydroxylhex-1-yl]-L-amino acid dichloroplatinates(II) with high anti-tumor activity and low side reaction

To discover whether novel anti-tumor platinum agents are capable of selectively accumulating in tumor tissue, three novel potassium N-[(2S,3R,4R,5R)-2,3,4,5,6-pentahydroxylhex-1-yl]-L-amino acid dichloroplatinates(II) were prepared. At a dose of 1.67 μmol kg(-1) the in vivo anti-tumor potencies of two of the compounds were higher than that of oxaliplatin. The mortality analysis indicated that these compounds resulted in a 100% survival rate, whereas oxaliplatin lead to an 80% survival rate. The organ damage examination indicated that these compounds induced less damage than oxaliplatin. The platinum accumulation in the organs, blood and bone was significantly lower than that of oxaliplatin treated mice, while the platinum accumulation in the tumor tissue was significantly higher than that of the oxaliplatin treated mice.     

A cell-based screen for inhibitors of protein folding and degradation

Cancer cells are exposed to external and internal stresses by virtue of their unrestrained growth, hostile microenvironment, and increased mutation rate. These stresses impose a burden on protein folding and degradation pathways and suggest a route for therapeutic intervention in cancer. Proteasome and Hsp90 inhibitors are in clinical trials and a 20S proteasome inhibitor, Velcade, is an approved drug. Other points of intervention in the folding and degradation pathway may therefore be of interest. We describe a simple screen for inhibitors of protein synthesis, folding, and proteasomal degradation pathways in this paper. The molecular chaperone-dependent client v-Src was fused to firefly luciferase and expressed in HCT-116 colorectal tumor cells. Both luciferase and protein tyrosine kinase activity were preserved in cells expressing this fusion construct. Exposing these cells to the Hsp90 inhibitor geldanamycin caused a rapid reduction of luciferase and kinase activities and depletion of detergent-soluble v-Src::luciferase fusion protein. Hsp70 knockdown reduced v-Src::luciferase activity and, when combined with geldanamycin, caused a buildup of v-Src::luciferase and ubiquitinated proteins in a detergent-insoluble fraction. Proteasome inhibitors also decreased luciferase activity and caused a buildup of phosphotyrosine-containing proteins in a detergent-insoluble fraction. Protein synthesis inhibitors also reduced luciferase activity, but had less of an effect on phosphotyrosine levels. In contrast, certain histone deacetylase inhibitors increased luciferase and phosphotyrosine activity. A mass screen led to the identification of Hsp90 inhibitors, ubiquitin pathway inhibitors, inhibitors of Hsp70/Hsp40-mediated refolding, and protein synthesis inhibitors. The largest group of compounds identified in the screen increased luciferase activity, and some of these increase v-Src levels and activity. When used in conjunction with appropriate secondary assays, this screen is a powerful cell-based tool for studying compounds that affect protein synthesis, folding, and degradation.     

Expressions and purification of a mature form of recombinant human Chemerin in Escherichia coli

Chemerin is a novel chemokine that binds to the G protein-coupled receptor (GPCR) ChemR23, also known as chemokine-like receptor 1 (CMKLR1). It is secreted as a precursor and executes pro-inflammatory functions when the last six amino acids are removed from its C-terminus by serine proteases. After maturation, Chemerin attracts dendritic cells and macrophages through binding to ChemR23. We report a new method for expression and purification of mature recombinant human Chemerin (rhChemerin) using a prokaryotic system. After being expressed in bacteria, rhChemerin in inclusion bodies was denatured using 6 M guanidine chloride. Soluble rhChemerin was prepared by the protein-specific renaturation solution under defined conditions. It was subsequently purified using ion-exchange columns to more than 95% purity with endotoxin level <1.0 EU/μg. We further demonstrated its biological activities for attracting migration of human dendritic cells and murine macrophages in vitro using established chemotaxis assays.     

Redox regulation of plant stem cell fate

Despite the importance of stem cells in plant and animal development, the common mechanisms of stem cell maintenance in both systems have remained elusive. Recently, the importance of hydrogen peroxide (H₂O₂) signaling in priming stem cell differentiation has been extensively studied in animals. Here, we show that different forms of reactive oxygen species (ROS) have antagonistic roles in plant stem cell regulation, which were established by distinct spatiotemporal patterns of ROS‐metabolizing enzymes. The superoxide anion () is markedly enriched in stem cells to activate WUSCHEL and maintain stemness, whereas H₂O₂ is more abundant in the differentiating peripheral zone to promote stem cell differentiation. Moreover, H₂O₂ negatively regulates biosynthesis in stem cells, and increasing H₂O₂ levels or scavenging leads to the termination of stem cells. Our results provide a mechanistic framework for ROS‐mediated control of plant stem cell fate and demonstrate that the balance between and H₂O₂ is key to stem cell maintenance and differentiation.     

Asymmetric reduction of ketopantolactone using a strictly (<Emphasis Type="Italic">R</Emphasis>)-stereoselective carbonyl reductase through efficient NADPH regeneration and the substrate constant-feeding strategy

Objectives

To characterize a recombinant carbonyl reductase from Saccharomyces cerevisiae (SceCPR1) and explore its use in asymmetric synthesis of (R)-pantolactone [(R)-PL].

Results

The NADPH-dependent SceCPR1 exhibited strict (R)-enantioselectivity and high activity in the asymmetric reduction of ketopantolactone (KPL) to (R)-PL. Escherichia coli, coexpressing SceCPR1 and glucose dehydrogenase from Exiguobacterium sibiricum (EsGDH), was constructed to fulfill efficient NADPH regeneration. During the whole-cell catalyzed asymmetric reduction of KPL, the spontaneous hydrolysis of KPL significantly affected the yield of (R)-PL, which was effectively alleviated by the employment of the substrate constant-feeding strategy. The established whole-cell bioreduction for 6 h afforded 458 mM (R)-PL with the enantiomeric excess value of >99.9% and the yield of 91.6%.

Conclusions

Escherichia coli coexpressing SceCPR1 and EsGDH efficiently catalyzed the asymmetric synthesis of (R)-PL through the substrate constant-feeding strategy.

     

Atrial fibrillation is not uncommon among patients with ischemic stroke and transient ischemic stroke in China

Background

Atrial fibrillation (AF) is reported to be a less frequent cause of ischemic stroke in China than in Europe and North America, but it is not clear whether this is due to underestimation. Our aim was to define the true frequency of AF-associated stroke, to determine the yield of 6-day Holter ECG to detect AF in Chinese stroke patients, and to elucidate predictors of newly detected AF.

Methods

Patients with acute ischemic stroke or transient ischemic attack (TIA) were enrolled in a prospective, multicenter cohort study of 6-day Holter monitoring within 7 days after stroke onset at 20 sites in China between 2013 and 2015. Independent predictors of newly-detected AF were determined by multivariate analysis.

Results

Among 1511 patients with ischemic stroke and TIA (mean age 63 years, 33.1% women), 305 (20.2%) had either previously known (196, 13.0%) or AF newly-detected by electrocardiography (53, 3.5%) or by 6-day Holter monitoring (56/1262, 4.4%). A history of heart failure (OR?=?4.70, 95%CI, 1.64–13.5), advanced age (OR?=?1.06, 95%CI, 1.04–1.09), NIHSS at admission (OR?=?1.06, 95%CI, 1.02–1.10), blood high density lipoprotein (HDL) (OR?=?1.52, 95%CI, 1.09–2.13), together with blood triglycerides (OR?=?0.64, 95%CI, 0.45–0.91) were independently associated with newly-detected AF.

Conclusions

Contrary to previous reports, AF-associated stroke is frequent (20%) in China if systemically sought. Prolonged noninvasive cardiac rhythm monitoring importantly increases AF detection in patients with recent ischemic stroke and TIA in China. Advanced age, history of heart failure, and higher admission NIHSS and higher level of HDL were independent indicators of newly-detected AF.

Trial registration

NCT02156765 (June 5, 2014).

     

Integrating Multi-Omics for Uncovering the Architecture of Cross-Talking Pathways in Breast Cancer

Cross-talk among abnormal pathways widely occurs in human cancer and generally leads to insensitivity to cancer treatment. Moreover, alterations in the abnormal pathways are not limited to single molecular level. Therefore, we proposed a strategy that integrates a large number of biological sources at multiple levels for systematic identification of cross-talk among risk pathways in cancer by random walk on protein interaction network. We applied the method to multi-Omics breast cancer data from The Cancer Genome Atlas (TCGA), including somatic mutation, DNA copy number, DNA methylation and gene expression profiles. We identified close cross-talk among many known cancer-related pathways with complex change patterns. Furthermore, we identified key genes (linkers) bridging these cross-talks and showed that these genes carried out consistent biological functions with the linked cross-talking pathways. Through identification of leader genes in each pathway, the architecture of cross-talking pathways was built. Notably, we observed that linkers cooperated with leaders to form the fundamentation of cross-talk of pathways which play core roles in deterioration of breast cancer. As an example, we observed that KRAS showed a direct connection to numerous cancer-related pathways, such as MAPK signaling pathway, suggesting that it may be a central communication hub. In summary, we offer an effective way to characterize complex cross-talk among disease pathways, which can be applied to other diseases and provide useful information for the treatment of cancer.