Gold amides as anticancer drugs: synthesis and activity studies

Modular gold amide chemotherapeutics: Access to modern chemotherapeutics with robust and flexible synthetic routes that are amenable to extensive customisation is a key requirement in drug synthesis and discovery. A class of chiral gold amide complexes featuring amino acid derived ligands is reported herein. They all exhibit in vitro cytotoxicity against two slow growing breast cancer cell lines with limited toxicity towards normal epithelial cells

Identification and Characterization of Full-Length cDNAs in Channel Catfish (Ictalurus punctatus) and Blue Catfish (Ictalurus furcatus)

Background: Genome annotation projects, gene functional studies, and phylogenetic analyses for a given organism all greatly benefit from access to a validated full-length cDNA resource. While increasingly common in model species, fulllength cDNA resources in aquaculture species are scarce. Methodology and Principal Findings: Through in silico analysis of catfish (Ictalurus spp.) ESTs, a total of 10,037 channel catfish and 7,382 blue catfish cDNA clones were identified as potentially encoding full-length cDNAs. Of this set, a total of 1,169 channel catfish and 933 blue catfish full-length cDNA clones were selected for re-sequencing to provide additional coverage and ensure sequence accuracy. A total of 1,745 unique gene transcripts were identified from the full-length cDNA set, including 1,064 gene transcripts from channel catfish and 681gene transcripts from blue catfish, with 416 transcripts shared between the two closely related species. Full-length sequence characteristics (ortholog conservation, UTR length, Kozak sequence, and conserved motifs) of the channel and blue catfish were examined in detail. Comparison of gene ontology composition between full-length cDNAs and all catfish ESTs revealed that the full-length cDNA set is representative of the gene diversity encoded in the catfish transcriptome. Conclusions: This study describes the first catfish full-length cDNA set constructed from several cDNA libraries. The catfish full-length cDNA sequences, and data gleaned from sequence characteristics analysis, will be a valuable resource fo

Treatment of human cancer cells with selenite or tellurite in combination with auranofin enhances cell death due to redox shift

Selenium is an essential trace element incorporated as selenocysteine in 25 human selenoproteins. Among them are thioredoxin reductases (TrxR) and glutathione peroxidases, all central proteins in the regulation of the cellular thiol redox state. In this paper the effects of selenite and tellurite treatment in human cancer cells are reported and compared. Our results show that both selenite and tellurite, at relatively low concentrations, are able to increase the expression of mitochondrial and cytosolic TrxR in cisplatin-sensitive (2008) and -resistant (C13*) phenotypes. We further investigated the cellular effects induced by selenite or tellurite in combination with the specific TrxR inhibitor auranofin. Selenite pretreatment induced a dramatic increase in auranofin cytotoxicity in both resistant and sensitive cells. Investigation of TrxR activity and expression levels as well as the cellular redox state demonstrated the involvement of TrxR inhibition and redox changes in selenite and auranofin combined action

Effects of the antioxidant Pycnogenol((R)) on cellular redox systems in U1285 human lung carcinoma cells

Pycnogenol, which is extracted from the bark of French maritime pine, has been shown to have antioxidant and free radical scavenging activities. Thioredoxin reductase (TrxR), glutathione peroxidase (GPx) and glutathione reductase (GR) are three central redox enzymes that are active in endogenous defence against oxidative stress in the cell. Treatment of cells with Pycnogenol decreased the activity of both TrxR and GPx in cells by more than 50%, but GR was not affected. As previously reported, both enzymes were induced after treatment with hydrogen peroxide and selenite. The presence of Pycnogenol efficiently decreased selenite-mediated reactive oxygen species (ROS) production. Addition of Pycnogenol after selenite treatment reduced the mRNA expression and activity of TrxR to basal levels. In contrast, the GPx activity was completely unaffected. The discrepancy between TrxR and GPx regulation may indicate that transcription of TrxR is induced primarily by oxidative stress. As TrxR is induced in various pathological conditions, including tumours and inflammatory conditions, decreased activity mediated by a non-toxic agent such as Pycnogenol may be of great value

Ebselen: A substrate for human thioredoxin reductase strongly stimulating its hydroperoxide reductase activity and a superfast thioredoxin oxidant

Ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one], a seleno-organic compound with glutathione peroxidase-like activity is used in clinical trials against stroke. Human and bovine TrxR catalyzed the reduction of ebselen to ebselen selenol by NADPH with an apparent K(M)-value of 2.5 μM and a k(cat) of 588 min(−1). The addition of thioredoxin (Trx) stimulated the TrxR-catalyzed reduction of ebselen several-fold. This result was caused by a very fast oxidation of reduced Trx by ebselen with a rate constant in excess of 2 × 10(7) M(−1) s(−1). This rate is orders of magnitude faster than the reaction of dithiol Trx with insulin disulfides. Ebselen competed with disulfide substrates for reduction by Trx and, therefore, acted as an inhibitor of protein disulfide reduction by the Trx system. The inherent H(2)O(2) reductase activity of mammalian TrxR dependent on its active-site selenocysteine residue was stimulated 10-fold by 2 μM ebselen and 25-fold in the additional presence of 5 μM Trx. Furthermore, the apparent K(M)-value of TrxR for H(2)O(2) was lowered 25-fold to about 100 μM. Our results demonstrate that ebselen is a TrxR peroxidase which, in the presence of Trx, acted as a mimic of a peroxiredoxin. The activity with TrxR and oxidation of reduced Trx offer mechanistic explanations for the in vivo effects of ebselen as an antioxidant and anti-inflammatory agent. Our results demonstrate that the mechanism of action of ebselen may be predominantly via the Trx system rather than via glutathione

Interaction of selenite and tellurite with thiol-dependent redox enzymes: Kinetics and mitochondrial implications

The interactions of selenite and tellurite with cytosolic and mitochondrial thioredoxin reductases (TrxR1 and TrxR2) and glutathione reductases (GR) from yeast and mammalian sources were explored. Both TrxR1 and TrxR2 act as selenite and tellurite reductases. Kinetic treatment shows that selenite has a greater affinity than tellurite with both TrxR1 and TrxR2. Considering both k(cat) and K(m), selenite shows a better catalytic efficiency than tellurite with TrxR1, whereas with TrxR2, the catalytic efficiency is similar for both chalcogens. Tellurite is a good substrate for GR, whereas selenite is almost completely ineffective. Selenite or tellurite determine a large mitochondrial permeability transition associated with thiol group oxidation. However, with increasing concentrations of both chalcogens, only about 25% of total thiols are oxidized. In isolated mitochondria, selenite or tellurite per se does not stimulate H(2)O(2) production, which, however, is increased by the presence of auranofin. They also determine a large oxidation of mitochondrial pyridine nucleotides. In ovarian cancer cells both chalcogens decrease the mitochondrial membrane potential. These results indicate that selenite and tellurite, interacting with the thiol-dependent enzymes, alter the balance connecting pyridine nucleotides and thiol redox state, consequently leading to mitochondrial and cellular alterations essentially referable to a disulfide stres