Multidrug resistance-associated proteins: Export pumps for conjugates with glutathione, glucuronate or sulfate

Developmental Expression of Drug Transporters and Conjugating Enzymes Involved in Enterohepatic Recycling: Implication for Pediatric Drug Dosing

Around 50% of the drugs used in children have never been tested for safety and efficacy in this vulnerable population. Immature drug elimination pathways can lead to drug toxicity when pediatric doses are determined using empirical methods such as body-surface area or body-weight-normalized adult dosing. In the absence of clinical data, physiologically-based pharmacokinetic (PBPK) modeling has emerged as a useful tool to predict drug pharmacokinetics in children. These models utilize developmental physiological data, including age-dependent differences in the abundance of drug-metabolizing enzymes and transporters (DMET), to mechanistically extrapolate adult pharmacokinetic data to children. The reported abundance data of hepatic DMET proteins in subcellular fractions isolated from frozen tissue are prone to high technical variability. Therefore, we carried out the proteomics-based quantification of hepatic drug transporters and conjugating enzymes in 50 pediatric and 8 adult human hepatocyte samples. Out of the 34 studied proteins, 28 showed a significant increase or decrease with age. While MRP6, OAT7, and SULT1E1 were highest in < 1-year-old samples, the abundance of P-gp and UGT1A4 was negligible in < 1-year-old samples and increased significantly after 1 year of age. Incorporation of the age-dependent abundance data in PBPK models can help improve pediatric dose prediction, leading to safer drug pharmacotherapy in children.

Insights into the Detoxification of Spruce Monoterpenes by the Eurasian Spruce Bark Beetle

Plant defence mechanisms, including physical barriers like toughened bark and chemical defences like allelochemicals, are essential for protecting them against pests. Trees allocate non-structural carbohydrates (NSCs) to produce secondary metabolites like monoterpenes, which increase during biotic stress to fend off pests like the Eurasian spruce bark beetle, ESBB (Ips typographus). Despite these defences, the ESBB infests Norway spruce, causing significant ecological damage by exploiting weakened trees and using pheromones for aggregation. However, the mechanism of sensing and resistance towards host allelochemicals in ESBB is poorly understood. We hypothesised that the exposure of ESBB to spruce allelochemicals, especially monoterpenes, leads to an upsurge in the important detoxification genes like P450s, GSTs, UGTs, and transporters, and at the same time, genes responsible for development must be compromised. The current study demonstrates that exposure to monoterpenes like R-limonene and sabiene effectively elevated detoxification enzyme activities. The differential gene expression (DGE) analysis revealed 294 differentially expressed (DE) detoxification genes in response to R-limonene and 426 DE detoxification genes in response to sabiene treatments, with 209 common genes between the treatments. Amongst these, genes from the cytochrome P450 family 4 and 6 genes (CP4 and CP6), esterases, glutathione S-transferases family 1 (GSTT1), UDP-glucuronosyltransferase 2B genes (UDB), and glucose synthesis-related dehydrogenases were highly upregulated. We further validated 19 genes using RT-qPCR. Additionally, we observed similar high expression levels of detoxification genes across different monoterpene treatments, including myrcene and α-pinene, suggesting a conserved detoxification mechanism in ESBB, which demands further investigation. These findings highlight the potential for molecular target-based beetle management strategies targeting these key detoxification genes.

P-glycoprotein inhibitors as an adjunct therapy for TB

The primary challenge in TB treatment is the emergence of multidrug-resistant TB (MDR-TB). One of the major factors responsible for MDR is the upregulation of efflux pumps. Permeation-glycoprotein (P-gp), an efflux pump, hinders the bioavailability of the administered drugs inside the infected cells. Simultaneously, angiogenesis, the formation of new blood vessels, contributes to drug delivery complexities. TB infection triggers a cascade of events that upregulates the expression of angiogenic factors and P-gp. The combined action of P-gp and angiogenesis foster the emergence of MDR-TB. Understanding these mechanisms is pivotal for developing targeted interventions to overcome MDR in TB. P-gp inhibitors, such as verapamil, and anti-angiogenic drugs, including bevacizumab, have shown improvement in TB drug delivery to granuloma. In this review, we discuss the potential of P-gp inhibitors as an adjunct therapy to shorten TB treatment.

Biochemical and molecular biomarkers and their association with anthropogenic chemicals in wintering Manx shearwaters (Puffinus puffinus)

Anthropogenic pollution poses a threat to marine conservation by causing chronic toxic effects. Seabirds have contact throughout their lives with pollutants like plastic, metals, polychlorinated biphenyls (PCBs), and organochlorine pesticides such as hexachlorocyclohexanes (HCHs). We assessed 155 Manx shearwaters (Puffinus puffinus) stranded along the Brazilian coast, analyzing associations between organic pollutants, plastic ingestion, biomarkers (transcript levels of aryl hydrocarbon receptor, cytochrome P450-1A-5 [CYP1A5], UDP-glucuronosyl-transferase [UGT1], estrogen receptor alpha-1 [ESR1], and heat shock protein-70 genes) and enzymes activity (ethoxy-resorufin O-deethylase and glutathione S-transferase [GST]). Plastic debris was found in 29 % of the birds. The transcription of UGT1 and CYP1A5 was significantly associated with hexachlorobenzene (HCB) and PCBs levels. ESR1 was associated with HCB and Mirex, and GST was associated with Drins and Mirex. While organic pollutants affected shearwaters more than plastic ingestion, reducing plastic availability remains relevant as xenobiotics are also potentially adsorbed onto plastics.

3-bromopyruvate induces morphological alteration and may initiate programmed cell death in Cryptococcus neoformans cells

3-Bromopyruvate (3BP), known for its potent anticancer properties, also exhibits remarkable efficacy against the pathogenic fungus Cryptococcus neoformans. So far it has been proven that the main fungicidal activity of 3BP is based on ATP depletion and a reduction of intracellular level of glutathione. The presented study includes a broad range of methods to further investigate the mechanistic effects of 3BP on C. neoformans cells. The use of flow cytometry allowed a thorough examination of their survival during 3BP treatment, while observations using electron microscopy made it possible to note the changes in cellular morphology. Utilizing ruthenium red, the study suggests a mitochondrial pathway may initiate programmed cell death in response to 3BP. Analysis of free radical generation and gene expression changes supports this hypothesis. These findings enhance comprehension of 3BP's mechanisms in fungal cells, paving the way for its potential application as a therapeutic agent against cryptococcosis.

Comparative physiological and transcriptome analysis provide insights into the inhibitory effect of 6-pentyl-2H-pyran-2-one on Clarireedia jacksonii

Clarireedia spp. is a destructive phytopathogenic fungus that causes turf dollar spot of bent-grass, leading to widespread lawn death. In this study, we explored the antifungal capability of 6-pentyl-2H-pyran-2-one (6PP), a natural metabolite volatilized by microorganisms, which plays an important role in the biological control of turfgrass dollar spot. However, the mechanisms by which 6PP inhibits Clarireedia jacksonii remain unknown. In the present study, C. jacksonii mycelial growth was inhibited by the 6PP treatment and the 6PP treatment damaged cell membrane integrity, causing an increase in relative conduc-tivity. Furthermore, physiological and biochemistry assay showed that 6PP treatment can enhance reactive oxygen species (ROS) levels, malondialdehyde (MDA) content obviously increased with 6PP exposure, increased alchohol dehydrogenase (ADH) and depleted acetalde-hyde dehydrogenase (ALDH), and activated the activities of many antioxidant enzymes in C. jacksonii. Gen Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that some genes in C. jacksonii after 6PP treatment related to integrity of the cell wall and membrane, and oxidative stress were significantly downregulated. It is worth mentioning that the fatty acid degradation pathway is significantly upregulated, with an increase in ATP content and ATP synthase activity, which may promote fungal cell apoptosis. Moreover, we found that the expression of ABC transporters, and glutathione metabolism encoding genes were increased to respond to external stimuli. Taken together, these findings revealed the potential antifungal mechanism of 6PP against Clarireedia spp., which also provides a theoretical basis for the commercial utilization of 6PP as a green pesticide in the future.

Cellular Compartmentalization, Glutathione Transport and Its Relevance in Some Pathologies

Reduced glutathione (GSH) is the most abundant non-protein endogenous thiol. It is a ubiquitous molecule produced in most organs, but its synthesis is predominantly in the liver, the tissue in charge of storing and distributing it. GSH is involved in the detoxification of free radicals, peroxides and xenobiotics (drugs, pollutants, carcinogens, etc.), protects biological membranes from lipid peroxidation, and is an important regulator of cell homeostasis, since it participates in signaling redox, regulation of the synthesis and degradation of proteins (S-glutathionylation), signal transduction, various apoptotic processes, gene expression, cell proliferation, DNA and RNA synthesis, etc. GSH transport is a vital step in cellular homeostasis supported by the liver through providing extrahepatic organs (such as the kidney, lung, intestine, and brain, among others) with the said antioxidant. The wide range of functions within the cell in which glutathione is involved shows that glutathione’s role in cellular homeostasis goes beyond being a simple antioxidant agent; therefore, the importance of this tripeptide needs to be reassessed from a broader metabolic perspective.

Anti-colon cancer effects of Spirulina polysaccharide and its mechanism based on 3D models

Spirulina polysaccharides (PSP) possess significant biological properties. However, it is still a lack of investigation on the anti-colorectal cancer effect and mechanism. In this study, PSP showed significant effects on LoVo cell spheroids with an IC₅₀ value of 0.1943 mg/mL. The analysis of transcriptomics and metabolomics indicated the impact of PSP on LoVo spheroid cells through involvement in the two pathways of "glycine, serine, and threonine metabolism" and "ABC transporters". And, the q-PCR data further verified the pointed mechanism of PSP on colon cancer (CC) by regulating the expression levels of relevant genes in the synthesis pathways of serine and glycine in tumor cells. Furthermore, the anti-colon cancer effects of PSP were verified via other human colon cancer cell lines HCT116 and HT29 spheroids (IC₅₀ = 0.0646 mg/mL and 0.2213 mg/mL, respectively), and three patient-derived organoids (PDOs) with IC₅₀ values ranging from 3.807 to 7.788 mg/mL. In addition, this study found that a mild concentration of PSP cannot enhance the anti-tumor effect of 5-Fu. And a significant inhibition was found of PSP in 5-Fu resistance organoids. These results illustrated that PSP could be a treatment or supplement for 5-Fu resistant colorectal cancer (CRC).

Lead and copper led to the dysregulation of bile acid homeostasis by impairing intestinal absorption in Bufo gargarizans larvae: An integrated metabolomics and transcriptomics approach

Bile acids, as metabolic regulators and signaling molecules, play key roles in the regulation of host metabolism and immune responses. Heavy metals such as lead (Pb) and copper (Cu) are widespread environmental pollutants that threaten public health. However, the effects of heavy metals on bile acid metabolism and the underlying molecular mechanisms remain unclear, particularly for ecologically important amphibian species. In the present research, the effects of exposure to environmentally-relevant concentrations of Pb (250 μg/L), Cu (50 μg/L), and a mixture of both (Mix) on bile acid metabolism and the underlying molecular mechanisms in the intestines of Bufo gargarizans larvae were comprehensively investigated using histopathology, metabolomics and transcriptomics analysis. Our results suggested that Pb and/or Cu caused histopathological damage to the intestine and liver, such as decreased intestinal epithelial cell height and dilated hepatic sinusoid. The total bile acid level was decreased in the Pb and Mix exposure groups but elevated in the Cu treatment. A significant decrease in the ratio of conjugated to unconjugated bile acids was present in all treatment groups. Also, the level of GCA was increased while TCA and TCDCA were decreased in all exposure groups. In addition, exposure to Pb and Cu altered the expression levels of genes related to intestinal absorption. For example, mrp2, mrp3 and aqp4 had higher expression in the Pb and Mix treatment groups, and aqp1 and mrp4 were increased in the Cu treatment group. Overall, we speculated that the dysregulation of bile acid homeostasis induced by Pb and Cu exposure may be due to impaired intestinal absorption. These findings raise further concerns about the hazards of Pb and/or Cu in influencing bile acid metabolism that might lead to the development of metabolic diseases and inflammatory disorders.

Time- and dose-dependent detoxification and reproductive endocrine disruption induced by tetrabromobisphenol A (TBBPA) in mussel Mytilus galloprovincialis

As a typical brominated flame retardant (BFR), tetrabromobisphenol A (TBBPA) has been frequently detected in both biotic and abiotic matrices in marine environment. Our previous study found that genes related to metabolism phase I/II/III as well as steroid metabolism in Mytilus galloprovincialis were significantly altered by TBBPA treatment. However, the time- and dose-dependent response profiles of these genes to TBBPA exposure were rarely reported. In this study, the time- and dose-dependent effects of TBBPA on detoxification and reproductive endocrine disruption in M. galloprovincialis were explored by evaluating the responses of related gene expressions, enzymatic activities and gametogenesis to different concentrations of TBBPA (0.6, 3, 15, 75 and 375 μg/L) for different durations (14, 21 and 28 days). The results showed that the TBBPA accumulation increased linearly with the increases of exposure time and dose. Cytochrome P450 family 3 (CYP3A1-like) cooperated with CYP4Y1 for phase I biotransformation of TBBPA in mussels. The dose-response curves of phase II/III genes (glutathione-S-transferase (GST), P-glycoprotein (ABCB), and multidrug resistance protein (ABCC)) showed similar response profiles to TBBPA exposure. The common induction of phase I/II/III (CYPs, GST, ABCB and ABCC) suggested TBBPA detoxification regulation in mussels probably occurred in a step-wise manner. Concurrently, direct sulfation mediated by sulfotransferases (SULTs) on TBBPA was also the vital metabolic mechanism for TBBPA detoxification, which was supported by the coincidence between up-regulation of SULT1B1 and TBBPA accumulation. The significant promotion of steroid sulfatase (STS) might result from TBBPA-sulfate catalyzed by SULT1B1 due to its chemical similarity to estrone-sulfate. Furthermore, the promotion of gametogenesis was consistent with the induction of STS, suggesting that STS might interrupt steroids hydrolysis process and was responsible for reproductive endocrine disruption in M. galloprovincialis. This study provides a better understanding of the detoxification and endocrine-disrupting mechanisms of TBBPA.

Mechanisms underlying Nrf2 nuclear translocation by non-lethal levels of hydrogen peroxide: p38 MAPK-dependent neutral sphingomyelinase2 membrane trafficking and ceramide/PKCζ/CK2 signaling

Hydrogen peroxide is an aerobic metabolite playing a central role in redox signaling and oxidative stress. H₂O₂ could activate redox sensitive transcription factors, such as Nrf2, AP-1 and NF-κB by different manners. In some cells, treatment with non-lethal levels of H₂O₂ induces rapid activation of Nrf2, which upregulates expression of a set of genes involved in glutathione (GSH) synthesis and defenses against oxidative damage. It depends on two steps, the rapid translational activation of Nrf2 and facilitation of Nrf2 nuclear translocation. We review the molecular mechanisms by which H₂O₂ induces nuclear translocation of Nrf2 in cultured cells by highlighting the role of neutral sphingomyelinase 2 (nSMase2), a GSH sensor. H₂O₂ enters cells through aquaporin channels in the plasma membrane and is rapidly reduced to H₂O by GSH peroxidases to consume cellular GSH, resulting in nSMase2 activation to generate ceramide. H₂O₂ also activates p38 MAP kinase, which enhances transfer of nSMase2 from perinuclear regions to plasma membrane lipid rafts to accelerate ceramide generation. Low levels of ceramide activate PKCζ, which then activates casein kinase 2 (CK2). These protein kinases are able to phosphorylate Nrf2 to stabilize and activate it. Notably, Nrf2 also binds to caveolin-1 (Cav1), which protects Nrf2 from Keap1-mediated degradation and limits Nrf2 nuclear translocation. We propose that Cav1serves as a signaling hub for the control of H₂O₂-mediated phosphorylation of Nrf2 by kinases, which results in release of Nrf2 from Cav1 to facilitate nuclear translocation. In summary, H₂O₂ induces GSH depletion which is recovered by Nrf2 activation dependent on p38/nSMase2/ceramide signaling.

Odorant Metabolism in Humans

Odorants are relatively small molecules which are easily taken up and distributed in the human body. Despite their relevance in everyday life, however, only a limited amount of evidence about their metabolism, pathways, and bioactivities in the human body exists. With this Review, we aim to encourage future interdisciplinary research on the function and mechanisms of the biotransformation of odorants, involving different disciplines such as nutrition, medicine, biochemistry, chemistry, and sensory sciences. Starting with a general overview of the different ways of odorant uptake and enzymes involved in the metabolism of odorants, a more precise description of biotransformation processes and their function in the oral cavity, the nose, the lower respiratory tract (LRT), and the gastrointestinal tract (GIT) is given together with an overview of the different routes of odorant excretion. Finally, perspectives for future research are discussed.

SP1-induced lncRNA DUBR promotes stemness and oxaliplatin resistance of hepatocellular carcinoma via E2F1-CIP2A feedback

Oxaliplatin-based chemotherapy is widely used to treat advanced hepatocellular carcinoma (HCC), but many patients develop drug resistance that leads to tumor recurrence. Cancer stem cells (CSCs) are known to contribute to chemoresistance, the underlying mechanism, however, remains largely unknown. In this study, we discovered a specificity protein 1 (SP1)-induced long noncoding RNA--DPPA2 upstream binding RNA (DUBR) and its high expression in HCC tissues and liver CSCs. DUBR was associated with HCC progression and poor chemotherapy response. Moreover, DUBR facilitated the stemness and oxaliplatin resistance of HCC in vitro and in vivo. Mechanistically, DUBR upregulated cancerous inhibitor of protein phosphatase 2A (CIP2A) expression through E2F1-mediated transcription regulation. DUBR also exerted function by binding microRNA (miR)-520d-5p as a competing endogenous RNA to upregulate CIP2A at mRNA level. CIP2A, in turn, stabilized E2F1 protein and activated the Notch1 signaling pathway, thereby increasing the stemness feature of HCC and leading to chemoresistance. In conclusion, we identified SP1/DUBR/E2F1-CIP2A as a critical axis to activate the Notch1 signaling pathway and promote stemness and chemoresistance of HCC. Therefore, DUBR could be a potential target in HCC treatment.

An update on pharmacogenetic factors influencing the metabolism and toxicity of artemisinin-based combination therapy in the treatment of malaria

INTRODUCTION

Artemisinin-based combination therapies (ACTs) are recommended first-line antimalarials for uncomplicated Plasmodium falciparum malaria. Pharmacokinetic/pharmacodynamic variation associated with ACT drugs and their effect is documented. It is accepted to an extent that inter-individual variation is genetically driven, and should be explored for optimized antimalarial use.

AREAS COVERED

We provide an update on the pharmacogenetics of ACT antimalarial disposition. Beyond presently used antimalarials, we also refer to information available for the most notable next-generation drugs under development. The bibliographic approach was based on multiple Boolean searches on PubMed covering all recent publications since our previous review.

EXPERT OPINION

The last 10 years have witnessed an increase in our knowledge of ACT pharmacogenetics, including the first clear examples of its contribution as an exacerbating factor for drug-drug interactions. This knowledge gap is still large and is likely to widen as a new wave of antimalarial drug is looming, with few studies addressing their pharmacogenetics. Clinically useful pharmacogenetic markers are still not available, in particular, from an individual precision medicine perspective. A better understanding of the genetic makeup of target populations can be valuable for aiding decisions on mass drug administration implementation concerning region-specific antimalarial drug and dosage options.

Simultaneous Quantification of Biothiols and Deciphering Diverse GSH Stability in Different Live Cells by 19F-Tag

GSH, Cys, Hcy, and H₂S are important biothiols and play important roles in the living systems. Quantitative and simultaneous determination of these biothiols under physiological conditions is still a challenge. Herein, we developed an effective ¹⁹F-reactive tag that readily interacts with these four biothiols for the generation of stable thioether products that have distinguishable ¹⁹F-chemical shifts. These thioester compounds encode the characteristic fingerprint profiles of each biothiols, allowing one to simultaneously quantify and determine these biothiols by 1D ¹⁹F NMR spectroscopy. The intra-/extracellular GSH in live cells was assessed by the established strategy, and remarkable variations in the GSH stability were determined between the normal mammalian cells and cancer cells. It is notable that GSH hydrolyzes efficiently in the out-membrane of the cancer cells and the lysates. In contrast, GSH remains stable in the tested normal cells.

Cadmium induced Fak -mediated anoikis activation in kidney via nuclear receptors (AHR/CAR/PXR)-mediated xenobiotic detoxification pathway

Cadmium (Cd) is a toxic heavy metal of considerable toxicity, possessing a serious environmental problem that threatening food safety and human health. However, the underlying mechanisms of Cd-induced nephrotoxicity and detoxification response remain largely unclear. Cd was administered at doses of 35, 70, and 140 mg/kg diet with feed for 90 days and produced potential damage to chickens' kidneys. The results showed that Cd exposure induced renal anatomical and histopathological injuries. Cd exposure up-regulated cytochrome P450 enzymes (CYP450s), activated nuclear xenobiotic receptors (NXRs) response, including aryl hydro-carbon receptor (AHR), constitutive androstane receptor (CAR), and pregnane X receptor (PXR) by low and moderate doses of Cd, and induced an increase in CYP isoforms expression. Cd exposure down-regulated phase II detoxification enzymes (glutathione-S-transferase (GST), glutathione peroxidase (GSH-PX) activities, and glutathione (GSH) content), and GST isoforms transcription . Furthermore, ATP-binding cassette (ABC) transporters, multidrug resistance protein (MRP1), and P-glycoprotein (P-GP) levels were elevated by low dose, but high dose inhibited the P-GP expression. Activation of detoxification enzymes lost their ability of resistance as increasing dose of Cd, afterwards brought into severe renal injury. Additionally, Cd suppressed focal adhesion kinase (Fak) and integrins protein expression as well as activated extrinsic pathway and intrinsic pathways, thereby producing anoikis. In conclusion, these results indicated that Cd induced Fak-mediated anoikis activation in the kidney via nuclear receptors (AHR/CAR/PXR)-mediated xenobiotic detoxification pathway.

LncRNA as a multifunctional regulator in cancer multi-drug resistance

BACKGROUND

Malignant tumors have become the most dangerous disease in recent years. Chemotherapy is the most effective treatment for this disease; however, the problem of drug resistance has become even more common, which leads to the poor prognosis of patients suffering from cancers. Thus, necessary measures should be taken to address these problems at the earliest. Many studies have demonstrated that drug resistance is closely related to the abnormal expressions of long non-coding RNAs (lncRNAs).

METHODS AND RESULTS

This review aimed to summarize the molecular mechanisms underlying the association of lncRNAs and the development of drug resistance and to find potential strategies for the clinical diagnosis and treatment of cancer drug resistance. Studies showed that lncRNAs can regulate the expression of genes through chromatin remodeling, transcriptional regulation, and post-transcriptional processing. Furthermore, lncRNAs have been reported to be closely related to the occurrence of malignant tumors. In summary, lncRNAs have gained attention in related fields during recent years. According to previous studies, lncRNAs have a vital role in several different types of cancers owing to their multiple mechanisms of action. Different mechanisms have different functions that could result in different consequences in the same disease.

CONCLUSIONS

LncRNAs closely participated in cancer drug resistance by regulating miRNA, signaling pathways, proteins, cancer stem cells, pro- and ant-apoptosis, and autophagy. lncRNAs can be used as biomarkers of the possible treatment target in chemotherapy, which could provide solutions to the problem of drug resistance in chemotherapy in the future.

Glutathione Participation in the Prevention of Cardiovascular Diseases

Cardiovascular diseases (CVD) (such as occlusion of the coronary arteries, hypertensive heart diseases and strokes) are diseases that generate thousands of patients with a high mortality rate worldwide. Many of these cardiovascular pathologies, during their development, generate a state of oxidative stress that leads to a deterioration in the patient's conditions associated with the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Within these reactive species we find superoxide anion (O2•-), hydroxyl radical (•OH), nitric oxide (NO•), as well as other species of non-free radicals such as hydrogen peroxide (H2O2), hypochlorous acid (HClO) and peroxynitrite (ONOO-). A molecule that actively participates in counteracting the oxidizing effect of reactive species is reduced glutathione (GSH), a tripeptide that is present in all tissues and that its synthesis and/or regeneration is very important to be able to respond to the increase in oxidizing agents. In this review, we will address the role of glutathione, its synthesis in both the heart and the liver, and its importance in preventing or reducing deleterious ROS effects in cardiovascular diseases.

Protective Role of Glutathione in the Hippocampus after Brain Ischemia

Stroke is a major cause of death worldwide, leading to serious disability. Post-ischemic injury, especially in the cerebral ischemia-prone hippocampus, is a serious problem, as it contributes to vascular dementia. Many studies have shown that in the hippocampus, ischemia/reperfusion induces neuronal death through oxidative stress and neuronal zinc (Zn²⁺) dyshomeostasis. Glutathione (GSH) plays an important role in protecting neurons against oxidative stress as a major intracellular antioxidant. In addition, the thiol group of GSH can function as a principal Zn²⁺ chelator for the maintenance of Zn²⁺ homeostasis in neurons. These lines of evidence suggest that neuronal GSH levels could be a key factor in post-stroke neuronal survival. In neurons, excitatory amino acid carrier 1 (EAAC1) is involved in the influx of cysteine, and intracellular cysteine is the rate-limiting substrate for the synthesis of GSH. Recently, several studies have indicated that cysteine uptake through EAAC1 suppresses ischemia-induced neuronal death via the promotion of hippocampal GSH synthesis in ischemic animal models. In this article, we aimed to review and describe the role of GSH in hippocampal neuroprotection after ischemia/reperfusion, focusing on EAAC1.

A therapeutic keypad lock decoded in drug resistant cancer cells

A molecular keypad lock that displays photodynamic activity when exposed to glutathione (GSH), esterase and light in the given order, is fabricated and its efficacy in drug resistant MCF7 cancer cells is investigated. The first two inputs are common drug resistant tumor markers. GSH reacts with the agent and shifts the absorption wavelength. Esterase separates the quencher from the structure, further activating the agent. After these sequential exposures, the molecular keypad lock is exposed to light and produces cytotoxic singlet oxygen. Among many possible combinations, only one 'key' can activate the agent, and initiate a photodynamic response. Paclitaxel resistant MCF7 cells are selectively killed. This work presents the first ever biological application of small molecular keypad locks.

The changes of MRP2 expression in three kinds of pulmonary inflammation models: the downregulation occurred in cigarette smoke extract (CSE) stimulation group and CSE plus LPS stimulation group, unchanged in LPS stimulation group

The transporter multidrug resistance protein 2 (MRP2) can transport some tobacco carcinogens and plays an important role in the transport of mediators related to pulmonary inflammatory diseases. However, it is not fully understood whether the pulmonary inflammation caused by cigarette smoke extract (CSE) and lipopolysaccharide (LPS) is related to the regulation of MRP2. In this study, CSE and LPS were used alone and in combination as stimuli to induce pulmonary inflammation. In addition, the establishment of a pulmonary inflammation model was verified by animal experiments in vivo. We found that compared with those in the control group, the expression of MRP2 protein was downregulated and the expression of inflammatory cytokines was upregulated in pulmonary inflammation in the CSE group and the CSE combined with LPS group. However, there was almost no change in the expression of MRP2 stimulated by LPS alone. Our results show that CSE and CSE combined with LPS downregulate the expression of MRP2 under inflammatory conditions, while LPS has almost no effect on the expression of MRP2 under inflammatory conditions. The in vivo experimental results of CSE combined with LPS were consistent with the cellular results of CSE combined with LPS, which provides a model and basis for other studies of the role of MRP2 in pulmonary inflammation.

Cisplatin chemotherapy and renal function

Cisplatin has been a mainstay of cancer chemotherapy since the 1970s. Despite its broad anticancer potential, its clinical use has regularly been constrained by kidney toxicities. This review details those biochemical pathways and metabolic conversions that underlie the kidney toxicities. A wide range of redox events contribute to the eventual physiological consequences of drug activities.

Environmentally Driven Color Variation in the Pearl Oyster Pinctada margaritifera var. cumingii (Linnaeus, 1758) Is Associated With Differential Methylation of CpGs in Pigment- and Biomineralization-Related Genes

Today, it is common knowledge that environmental factors can change the color of many animals. Studies have shown that the molecular mechanisms underlying such modifications could involve epigenetic factors. Since 2013, the pearl oyster Pinctada margaritifera var. cumingii has become a biological model for questions on color expression and variation in Mollusca. A previous study reported color plasticity in response to water depth variation, specifically a general darkening of the nacre color at greater depth. However, the molecular mechanisms behind this plasticity are still unknown. In this paper, we investigate the possible implication of epigenetic factors controlling shell color variation through a depth variation experiment associated with a DNA methylation study performed at the whole genome level with a constant genetic background. Our results revealed six genes presenting differentially methylated CpGs in response to the environmental change, among which four are linked to pigmentation processes or regulations (GART, ABCC1, MAPKAP1, and GRL101), especially those leading to darker phenotypes. Interestingly, the genes perlucin and MGAT1, both involved in the biomineralization process (deposition of aragonite and calcite crystals), also showed differential methylation, suggesting that a possible difference in the physical/spatial organization of the crystals could cause darkening (iridescence or transparency modification of the biomineral). These findings are of great interest for the pearl production industry, since wholly black pearls and their opposite, the palest pearls, command a higher value on several markets. They also open the route of epigenetic improvement as a new means for pearl production improvement.

A smart MnO2-doped graphene oxide nanosheet for enhanced chemo-photodynamic combinatorial therapy via simultaneous oxygenation and glutathione depletion

The combination of chemotherapy and photodynamic therapy provides a promising approach for enhanced tumor eradication by overcoming the limitations of each individual therapeutic modality. However, tumor is pathologically featured with extreme hypoxia together with the adaptable overexpression of anti-oxidants, such as glutathione (GSH), which greatly restricts the therapeutic efficiency. Here, a combinatorial strategy was designed to simultaneously relieve tumor hypoxia by self-oxygenation and reduce intracellular GSH level to sensitize chemo-photodynamic therapy. In our system, a novel multi-functional nanosystem based on MnO₂-doped graphene oxide (GO) was developed to co-load cisplatin (CisPt) and a photosensitizer (Ce6). With MnO₂ doping, the nanosystem was equipped with intelligent functionalities: (1) catalyzes the decomposition of H₂O₂ into oxygen to relieve the tumor hypoxia; (2) depletes GSH level in tumor cells, and (3) concomitantly generates Mn²⁺ to proceed Fenton-like reaction, all of which contribute to the enhanced anti-tumor efficacy. Meanwhile, the surface hyaluronic acid (HA) modification could facilitate the targeted delivery of the nanosystem into tumor cells, thereby resulting in amplified cellular toxicity, as well as tumor growth inhibition in nude mice model. This work sheds a new light on the development of intelligent nanosystems for synergistic combination therapy via regulating tumor microenvironment.

Pesticides-induced Cardiovascular Dysfunctions: Prevalence and Associated Mechanisms

Increased applications of pesticides, mainly in agriculture and public health, have resulted in increased chances of human exposure to pesticides. Chronic exposure to pesticides has been implicated in several human diseases, including cardiovascular diseases. Cardiovascular diseases are broadly used for various heart pathological conditions, including a defect in blood vessels, and they include myocardial infarction, atherosclerosis, stroke, cardiomyopathy, coronary heart disease, etc. In this review, the association between human exposure to pesticides and the development of cardiovascular diseases was discussed using epidemiological and laboratory data. The toxicokinetics of pesticides in humans was reviewed, as well as the risk factors for cardiovascular diseases. The important role of oxidative stress principally the induction of reactive oxygen species as the signaling molecules for various signaling pathways involved in pesticides-induced cardiovascular disease, was discussed.

Cancer stem cells and nanomedicine: new opportunities to combat multidrug resistance?

'Multidrug resistance' (MDR) is a difficult challenge for cancer treatment. The combined role of cytochrome P450 enzymes (CYPs) and active efflux transporters (AETs) in cancer cells appears relevant in inducing MDR. Chemotherapeutic drugs can be substrates of both CYPs and AETs and CYP inducers or inhibitors can produce the same effects on AETs. In addition, a small subpopulation of cancer stem-like cells (CSCs) appears to survive conventional chemotherapy, leading to recurrent disease. Natural products appear efficacious against CSCs; their combinational treatments with standard chemotherapy are promising for cancer eradication, in particular when supported by nanotechnologies.

Research Progress on Long Non-coding RNAs and Drug Resistance of Breast Cancer

Breast cancer, as the foremost cause of women's death in the world, is highly metastatic and mutable. Resistance to drugs for chemotherapies, endocrine therapies, and targeted therapies is an important factor that impacts the prognosis of breast cancer. Long non-coding ribonucleic acids (LncRNAs) are crucial regulators of intracellular gene expressions. Some researchers have suggested that expression level of several types of LncRNAs were closely related to the prognosis of patients with breast cancer. LncRNAs significantly impact biological processes such as drug transport, detoxication, apoptosis, epithelial to mesenchymal transition (EMT), and autophagy by regulating intracellular signaling pathways such as multi-drug resistance gene 1 (MDR1), nuclear factor erythroid 2-related factor 2 (NRF2), phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), transforming growth factor-β (TGF-β), BRCA1/2, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This paper will summarize research progress on correlations between LncRNA and drug resistance of breast cancer. It will particularly expound molecular mechanisms through which LncRNAs regulate drug resistance of breast cancer. It will further discuss the feasibility as molecular markers for forecasting drug resistance of breast cancer and may be becoming new targets for treating breast cancer in the future.

Redox Regulation via Glutaredoxin-1 and Protein S-Glutathionylation

Significance: Over the past several years, oxidative post-translational modifications of protein cysteines have been recognized for their critical roles in physiology and pathophysiology. Cells have harnessed thiol modifications involving both oxidative and reductive steps for signaling and protein processing. One of these stages requires oxidation of cysteine to sulfenic acid, followed by two reduction reactions. First, glutathione (reduced glutathione [GSH]) forms a S-glutathionylated protein, and second, enzymatic or chemical reduction removes the modification. Under physiological conditions, these steps confer redox signaling and protect cysteines from irreversible oxidation. However, oxidative stress can overwhelm protein S-glutathionylation and irreversibly modify cysteine residues, disrupting redox signaling. Critical Issues: Glutaredoxins mainly catalyze the removal of protein-bound GSH and help maintain protein thiols in a highly reduced state without exerting direct antioxidant properties. Conversely, glutathione S-transferase (GST), peroxiredoxins, and occasionally glutaredoxins can also catalyze protein S-glutathionylation, thus promoting a dynamic redox environment. Recent Advances: The latest studies of glutaredoxin-1 (Glrx) transgenic or knockout mice demonstrate important distinct roles of Glrx in a variety of pathologies. Endogenous Glrx is essential to maintain normal hepatic lipid homeostasis and prevent fatty liver disease. Further, in vivo deletion of Glrx protects lungs from inflammation and bacterial pneumonia-induced damage, attenuates angiotensin II-induced cardiovascular hypertrophy, and improves ischemic limb vascularization. Meanwhile, exogenous Glrx administration can reverse pathological lung fibrosis. Future Directions: Although S-glutathionylation modifies many proteins, these studies suggest that S-glutathionylation and Glrx regulate specific pathways in vivo, and they implicate Glrx as a potential novel therapeutic target to treat diverse disease conditions. Antioxid. Redox Signal. 32, 677-700.

Adverse effects of perfluoroalkyl acids on fish and other aquatic organisms: A review

Perfluoroalkyl acids (PFAAs) have been widely used in many industrial and consumer products. They have been detected ubiquitously in ambient water along with other environmental matrices, and their adverse effects on aquatic organisms have been a subject of active investigation. Here, we intended to summarize and synthesize the existing body of knowledge on PFAA toxicity through an extensive literature review, and shed light on areas where further research is warranted. PFAA toxicity appears to be influenced by the sex and developmental stages of aquatic organisms, but not significantly by exposure route. PFAA-induced aquatic toxicity could be classified as metabolism disturbance, reproduction disruption, oxidative stress, developmental toxicity, thyroid disruption, etc. At the molecular level, these responses can be initiated by key events, such as nuclear receptor activation, reactive oxygen species induction, or interaction with a membrane, followed by a cascade of downstream responses. PFAA-induced toxicity involves diverse metabolic processes, and therefore elucidating crosstalk or interactions among diverse metabolic pathways is a challenging task. In the presence of other chemicals, PFAAs can function as agonists or antagonists, resulting in different directions of combined toxicity. Therefore, mixture toxicity with other groups of chemicals is another research opportunity. Experimental evidence supports the trans-generational toxicity of PFAAs, suggesting that their long-term consequences for aquatic ecosystems should become of concern. A recent global ban of several PFAAs resulted in an increasing dependence on PFAA alternatives. The lack of sufficient toxicological information on this emerging group of chemicals warrant caution and rigorous toxicological assessments.

Probing the Role of the Chloroplasts in Heavy Metal Tolerance and Accumulation in Euglena gracilis

The E. gracilis Zm-strain lacking chloroplasts, characterized in this study, was compared with the earlier assessed wild type Z-strain to explore the role of chloroplasts in heavy metal accumulation and tolerance. Comparison of the minimum inhibitory concentration (MIC) values indicated that both strains tolerated similar concentrations of mercury (Hg) and lead (Pb), but cadmium (Cd) tolerance of the Z-strain was twice that of the Zm-strain. The ability of the Zm-strain to accumulate Hg was higher compared to the Z-strain, indicating the existence of a Hg transportation and accumulation mechanism not depending on the presence of chloroplasts. Transmission electron microscopy (TEM) showed maximum accumulation of Hg in the cytosol of the Zm-strain and highest accumulation of Cd in the chloroplasts of the Z-strain indicating a difference in the ability of the two strains to deposit heavy metals in the cell. The highly abundant heavy metal transporter MTP2 in the Z-strain may have a role in Cd transportation to the chloroplasts. A multidrug resistance-associated protein highly increased in abundance in the Zm-strain could be a potential Hg transporter to either cytosol or mitochondria. Overall, the chloroplasts appear to have major role in the tolerance and accumulation of Cd in E. gracilis.

Metabolic Remodelling: An Accomplice for New Therapeutic Strategies to Fight Lung Cancer

Metabolic remodelling is a hallmark of cancer, however little has been unravelled in its role in chemoresistance, which is a major hurdle to cancer control. Lung cancer is a leading cause of death by cancer, mainly due to the diagnosis at an advanced stage and to the development of resistance to therapy. Targeted therapeutic agents combined with comprehensive drugs are commonly used to treat lung cancer. However, resistance mechanisms are difficult to avoid. In this review, we will address some of those therapeutic regimens, resistance mechanisms that are eventually developed by lung cancer cells, metabolic alterations that have already been described in lung cancer and putative new therapeutic strategies, and the integration of conventional drugs and genetic and metabolic-targeted therapies. The oxidative stress is pivotal in this whole network. A better understanding of cancer cell metabolism and molecular adaptations underlying resistance mechanisms will provide clues to design new therapeutic strategies, including the combination of chemotherapeutic and targeted agents, considering metabolic intervenients. As cancer cells undergo a constant metabolic adaptive drift, therapeutic regimens must constantly adapt.

Rapid maturation of the hepatic cell line Huh7 via CDK inhibition for PXR dependent CYP450 metabolism and induction

CYP3A4, a cytochrome P450 enzyme regulated by the nuclear receptor PXR, is involved in most of the drug metabolizing pathways. Studying the regulation/induction of CYP3A4 and PXR is critical in toxicology and drug-drug interaction (DDI) studies. Primary human hepatocytes constitute the preferred in vitro platform for drug development efforts. However, they are expensive, scarce and heterogeneous. Hepatic cell lines, such as Huh7, could provide a cost-effective alternative, however, they express negligible amounts of CYP450s and PXR. In this study, we show that dinaciclib, a potent cyclin dependent kinase inhibitor, significantly increases the basal CYP3A4 and PXR levels in 24 hours. We also demonstrated that matured Huh7s can be used for drug induction studies, where CYP3A4, CYP1A2, CYP2C9, and CYP2C19 inductions were achieved following rifampicin treatment. More importantly, through a direct demonstration using amiodarone and rifampicin as model drugs, we showed that matured Huh7s present a suitable platform for DDI studies.

Selective Transport of Protein-Bound Uremic Toxins in Erythrocytes

To better understand the kinetics of protein-bound uremic toxins (PBUTs) during hemodialysis (HD), we investigated the distribution of hippuric acid (HA), indole-3-acetic acid (IAA), indoxyl sulfate (IS), and p-cresyl sulfate (pCS) in erythrocytes of HD patients. Their transport across the erythrocyte membrane was explored in the absence of plasma proteins in vitro in a series of loading and unloading experiments of erythrocytes from healthy subjects and HD patients, respectively. Furthermore, the impact of three inhibitors of active transport proteins in erythrocytes was studied. The four PBUTs accumulated in erythrocytes from HD patients. From loading and unloading experiments, it was found that (i) the rate of transport was dependent on the studied PBUT and increased in the following sequence: HA < IS < pCS < IAA and (ii) the solute partition of intra- to extra-cellular concentrations was uneven at equilibrium. Finally, inhibiting especially Band 3 proteins affected the transport of HA (both in loading and unloading), and of IS and pCS (loading). By exploring erythrocyte transmembrane transport of PBUTs, their kinetics can be better understood, and new strategies to improve their dialytic removal can be developed.

The glutathione system and the related thiol network in Caenorhabditis elegans

Advances in the field of redox biology have contributed to the understanding of the complexity of the thiol-based system in mediating signal transduction. The redox environment is the overall spatiotemporal balance of oxidation-reduction systems within the integrated compartments of the cell, tissues and whole organisms. The ratio of the reduced to disulfide glutathione redox couple (GSH:GSSG) is a key indicator of the redox environment and its associated cellular health. The reaction mechanisms of glutathione-dependent and related thiol-based enzymes play a fundamental role in the function of GSH as a redox regulator. Glutathione homeostasis is maintained by the balance of GSH synthesis (de novo and salvage pathways) and its utilization through its detoxification, thiol signalling, and antioxidant defence functions via GSH-dependent enzymes and free radical scavenging. As such, GSH acts in concert with the entire redox network to maintain reducing conditions in the cell. Caenorhabditis elegans offers a simple model to facilitate further understanding at the multicellular level of the physiological functions of GSH and the GSH-dependent redox network. This review discusses the C. elegans studies that have investigated glutathione and related systems of the redox network including; orthologs to the protein-encoding genes of GSH synthesis; glutathione peroxidases; glutathione-S-transferases; and the glutaredoxin, thioredoxin and peroxiredoxin systems.

Transcriptome analysis of genes and metabolic pathways associated with nicotine degradation in Aspergillus oryzae 112822

BACKGROUND

Nicotine-degrading microorganisms (NDMs) have recently received much attention since they can consume nicotine as carbon and nitrogen source for growth. In our previous work, we isolated an efficient nicotine-degrading fungus Aspergillus oryzae 112822 and first proposed a novel demethylation pathway of nicotine degradation in fungi. However, the underlying mechanisms of the demethylation pathway remain unresolved. In the present study, we performed a comparative transcriptome analysis to elucidate the molecular mechanisms of nicotine tolerance and degradation in A. oryzae 112822.

RESULTS

We acquired a global view of the transcriptional regulation of A. oryzae 112822 exposed to nicotine and identified 4381 differentially expressed genes (DEGs) by nicotine treatment. Candidate genes encoding cytochrome P450 monooxygenases (CYPs), FAD-containing amine oxidase, molybdenum cofactor (Moco)-containing hydroxylase, and NADH-dependent and FAD-containing hydroxylase were proposed to participate in the demethylation pathway of nicotine degradation. Analysis of these data also revealed that increased energy was invested to drive nicotine detoxification. Nicotine treatment led to overproduction of reactive oxygen species (ROS), which formed intracellular oxidative stress that could induce the expression of several antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxiredoxin (Prx). Thioredoxin system was induced to restore the intracellular redox homeostasis. Several glutathione S-transferases (GSTs) were induced, most likely to participate in phase II detoxification of nicotine by catalyzing the conjugation of glutathione (GSH) to active metabolites. The toxin efflux pumps, such as the ATP-Binding Cassette (ABC) transporters and the major facilitator superfamily (MFS) transporters, were overexpressed to overcome the intracellular toxin accumulation. By contrast, the metabolic pathways related to cellular growth and reproduction, such as ribosome biogenesis and DNA replication, were inhibited by nicotine treatment.

CONCLUSION

These results revealed that complex regulation networks, involving detoxification, transport, and oxidative stress response accompanied by increased energy investment, were developed for nicotine tolerance and degradation in A. oryzae 112822. This work provided the first insight into the metabolic regulation of nicotine degradation and laid the foundation for further revealing the molecular mechanisms of the nicotine demethylation pathway in filamentous fungi.

Glutathione antioxidant system and methylmercury-induced neurotoxicity: An intriguing interplay

Methylmercury (MeHg) is a toxic chemical compound naturally produced mainly in the aquatic environment through the methylation of inorganic mercury catalyzed by aquatic microorganisms. MeHg is biomagnified in the aquatic food chain and, consequently, piscivorous fish at the top of the food chain possess huge amounts of MeHg (at the ppm level). Some populations that have fish as main protein's source can be exposed to exceedingly high levels of MeHg and develop signs of toxicity. MeHg is toxic to several organs, but the central nervous system (CNS) represents a preferential target, especially during development (prenatal and early postnatal periods). Though the biochemical events involved in MeHg-(neuro)toxicity are not yet entirely comprehended, a vast literature indicates that its pro-oxidative properties explain, at least partially, several of its neurotoxic effects. As result of its electrophilicity, MeHg interacts with (and oxidize) nucleophilic groups, such as thiols and selenols, present in proteins or low-molecular weight molecules. It is noteworthy that such interactions modify the redox state of these groups and, therefore, lead to oxidative stress and impaired function of several molecules, culminating in neurotoxicity. Among these molecules, glutathione (GSH; a major thiol antioxidant) and thiol- or selenol-containing enzymes belonging to the GSH antioxidant system represent key molecular targets involved in MeHg-neurotoxicity. In this review, we firstly present a general overview concerning the neurotoxicity of MeHg. Then, we present fundamental aspects of the GSH-antioxidant system, as well as the effects of MeHg on this system.

Pesticide toxicity: a mechanistic approach

Pesticides are known for their high persistence and pervasiveness in the environment, and along with products of their biotransformation, they may remain in and interact with the environment and living organisms in multiple ways, according to their nature and chemical structure, dose and targets. In this review, the classifications of pesticides based on their nature, use, physical state, pathophysiological effects, and sources are discussed. The effects of these xenobiotics on the environment, their biotransformation in terms of bioaccumulation are highlighted with special focus on the molecular mechanisms deciphered to date. Basing on targeted organisms, most pesticides are classified as herbicides, fungicides, and insecticides. Herbicides are known as growth regulators, seedling growth inhibitors, photosynthesis inhibitors, inhibitors of amino acid and lipid biosynthesis, cell membrane disrupters, and pigment biosynthesis inhibitors, whereas fungicides include inhibitors of ergosterol biosynthesis, protein biosynthesis, and mitochondrial respiration. Insecticides mainly affect nerves and muscle, growth and development, and energy production. Studying the impact of pesticides and other related chemicals is of great interest to animal and human health risk assessment processes since potentially everyone can be exposed to these compounds which may cause many diseases, including metabolic syndrome, malnutrition, atherosclerosis, inflammation, pathogen invasion, nerve injury, and susceptibility to infectious diseases. Future studies should be directed to investigate influence of long term effects of low pesticide doses and to minimize or eliminate influence of pesticides on non-target living organisms, produce more specific pesticides and using modern technologies to decrease contamination of food and other goods by pesticides.

N-acetylcysteine ethyl ester as GSH enhancer in human primary endothelial cells: A comparative study with other drugs

Several drugs are currently in use as glutathione (GSH) enhancers in clinical, pre-clinical and experimental research. Here we compare the ability of N-acetylcysteine (NAC), 2-oxothiazolidine-4-carboxylic acid (OTC), glutathione ethyl ester (GSH-EE) and N-acetylcysteine ethyl ester (NACET) to increase the intracellular concentration of GSH using primary human umbilical vein endothelial cells (HUVEC) as in vitro model. Our experiments highlighted that NACET is largely the most efficient molecule in increasing the intracellular levels of GSH, cysteine, and γ-glutamylcysteine. This is because NACET is lipophilic and can freely cross plasma membrane but, inside the cell, it is de-esterified to the more hydrophilic NAC, which, in turn, is trapped into the cell and slowly transformed into cysteine. The higher availability of cysteine is matched by an increase in GSH synthesis, cysteine availability being the rate limiting step for this reaction. Surprisingly, the increase in GSH concentration was not linear but peaked at 0.5 mM NACET and gradually decreased when cells were treated with higher concentrations of NACET. We demonstrated that this puzzling ceiling effect was due to the fact that NAC released from NACET turned out to be a competitive inhibitor of the enzyme glutamate-cysteine ligase, with a Ki value of 3.2 mM. By using a cell culture medium lacking of cysteine and methionine, we could demonstrate that the slight increase in intracellular levels of cysteine and GSH induced by NAC in HUVEC grown in standard medium was due to the reduction of the cystine present in the medium itself there rather than to the action of NAC as Cys pro-drug. This fact may explain why NAC works well as GSH enhancer at very high concentrations in pre-clinical and in vitro studies, whereas it failed in most clinical trials.

Biological Activity of Flavonoids and Rare Sesquiterpene Lactones Isolated From Centaurea ragusina L

The endemic Croatian species Centaurea ragusina L., like other species from the genus Centaurea, has been traditionally used in Croatia as an antibacterial agent and for the treatment of gastrointestinal and urogenital disorders. In several chromatographic steps, three flavonoids and three sesquiterpene lactones (STLs) were isolated and identified from the most active fractions of the ethanol extract. Two STLs, one for which we created the trivial name ragusinin, and hemistepsin A are here reported for the first time as constituents of the genus Centaurea. All six compounds were screened for their effect on several tumor and one normal cell lines. Among them, ragusinin showed the best bioactivity and high specificity to affect tumor murine SCCVII, human HeLa and Caco-2 cell lines, but not the viability of normal V79 fibroblasts. Due to these characteristics the action of ragusinin was investigated in more detail. Since DNA is the primary target for many drugs with antibacterial and anticancer activity, we studied its interaction with ragusinin. Rather moderate binding affinity to DNA excluded it as the primary target of ragusinin. Due to the possibility of STL interaction with glutathione (GSH), the ubiquitous peptide that traps reactive compounds and other xenobiotics to prevent damage to vital proteins and nucleic acids, its role in deactivation of ragusinin was evaluated. Addition of the GSH precursor N-acetyl-cysteine potentiated the viability of HeLa cells, while the addition of GSH inhibitor L-buthionine sulfoximine decreased it. Moreover, pre-treatment of HeLa cells with the inhibitor of glutathione-S-transferase decreased their viability indicating the detoxifying role of GSH in ragusinin treated cells. Cell death, derived by an accumulation of cells in a G2 phase of the cell cylce, was shown to be independent of poly (ADP-ribose) polymerase and caspase-3 cleavage pointing toward an alternative cell death pathway.

Effects of Camellia sinensis crude saponin on survival and biochemical markers of oxidative stress and multixenobiotic resistance of the Mediterranean mussel, Mytilus galloprovincialis

The Ebro Delta (NE Spain), formed by two bays, northern and southern hemidelta, is an area mainly devoted to rice farming. As a result shellfish species inhabiting or cultured in nearby bays may become increasingly threatened by exposure to pollutants associated to agriculture. The latest product applied in the rice fields is a plant based molluscicide called saponin, used to control populations of the giant apple snail (GAS). Saponins are known to also affect other organisms, hence research of its toxicity towards non target species is needed. In this study, mussels (Mytilus galloprovincialis) were exposed to three concentrations of suspended solid pellets containing saponin extracts from the plant species Camellia sinensis. Effects across a large set of biochemical markers were investigated in the digestive gland and gill tissue of exposed mussels to saponin for 1 and 7days. In addition, crude saponin was extracted from solid pellets to confirm its correct concentration. Results obtained from this study, showed that the concentration of crude saponin in dry pellets was of 5.5%. Lethal levels of saponin were 3.2 fold higher than the maximal predicted field concentration, and activated respiratory metabolism and expression of transmembrane protein transporters. Mussels, exposed to sub lethal concentrations of saponin showed increase of antioxidant defenses.

The Anopheles gambiae ATP-binding cassette transporter family: phylogenetic analysis and tissue localization provide clues on function and role in insecticide resistance

The role of ATP-binding cassette (ABC) transporters in conferring insecticide resistance has received much attention recently. Here we identify ABC transporters differentially expressed in insecticide-resistant populations of the malaria vector, Anopheles gambiae. Although we found little evidence that the orthologues of the multidrug resistance proteins described in other species are associated with resistance in An. gambiae we did identify a subset of ABC proteins consistently differentially expressed in pyrethroid-resistant populations from across Africa. We present information on the phylogenetic relationship, primary sites of expression and potential role of ABC transporters in mediating the mosquito's response to insecticides. Furthermore we demonstrate that a paralogous group of eight ABCG transporters, clustered on chromosome 3R, are highly enriched in the legs of An. gambiae mosquitoes, consistent with a proposed role for this ABC subfamily in transport of lipids to the outer surface of the cuticle. Finally, antibodies raised against one of the most highly expressed ABC transporters in adult females, ABCG7 (AGAP009850), localized this transporter to the pericardial cells. These data will help prioritize members of this gene family for further localization and functional validation studies to identify the in vivo function of these transporters in the mosquito and determine whether elevated expression of members of this family contribute to insecticide resistance.

Glutathione transferases: substrates, inihibitors and pro-drugs in cancer and neurodegenerative diseases

Glutathione transferase classical GSH conjugation activity plays a critical role in cellular detoxification against xenobiotics and noxious compounds as well as against oxidative stress. However, this feature is also exploited by cancer cells to acquire drug resistance and improve their survival. As a result, various members of the family were found overexpressed in a number of different cancers. Moreover several GST polymorphisms, ranging from null phenotypes to point mutations, were detected in members of the family and found to correlate with the onset of neuro-degenerative diseases. In the last decades, a great deal of research aimed at clarifying the role played by GSTs in drug resistance, at developing inhibitors to counteract this activity but also at exploiting GSTs for prodrugs specific activation in cancer cells. Here we summarize some of the most important achievements reached in this lively area of research.