Proteasome activation: A novel strategy for targeting undruggable intrinsically disordered proteins.

Intrinsically disordered proteins (IDPs) are characterized by their inability to adopt well-defined tertiary structures under physiological conditions. Nonetheless, they often play pivotal roles in the progression of various diseases, including cancer, neurodegenerative disorders, and cardiovascular ailments. Owing to their inherent dynamism, conventional drug design approaches based on structural considerations encounter substantial challenges when applied to IDPs. Consequently, the pursuit of therapeutic interventions directed towards IDPs presents a complex endeavor. While there are indeed existing methodologies for targeting IDPs, they are encumbered by noteworthy constrains. Hence, there exists an imminent imperative to investigate more efficacious and universally applicable strategies for modulating IDPs. Here, we present an overview of the latest advancements in the research pertaining to IDPs, along with the indirect regulation approach involving the modulation of IDP degradation through proteasome. By comprehending these advancements in research, novel insights can be generated to facilitate the development of new drugs targeted at addressing the accumulation of IDPs in diverse pathological conditions.

Design, synthesis, and anticancer evaluation of alkynylated pyrrole derivatives.

A series of alkynylated pyrrole derivatives were meticulously designed, drawing inspiration from the structure of 3-alkynylpyrrole-2,4-dicarboxylates, which were synthesized via a cyclization process involving methylene isocyanides and propiolaldehydes under mild conditions. These derivatives were subsequently subjected to evaluation for their anticancer properties against a panel of cell lines, including U251, A549, 769-P, HepG2, and HCT-116. According to the detailed analysis of structure-activity relationship, compound 12l emerged as the most promising molecule, with IC50 values of 2.29 ± 0.18 and 3.49 ± 0.30 µM toward U251 and A549 cells, respectively. Subsequent mechanistic investigations revealed that compound 12l exerts its effects by arresting the cell cycle in the G0/G1 phase and inducing apoptosis specifically in A549 cells. These innovative alkynylated pyrrole derivatives hold the potential to serve as a valuable template for the discovery of novel anticancer molecules.

Recent progress and applications of small molecule inhibitors of Keap1-Nrf2 axis for neurodegenerative diseases.

The Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway serves as a crucial regulator against oxidative stress (OS) damage in various cells and organs. It has garnered significant attention as a potential therapeutic target for neurodegenerative diseases (NDD). Although progress has been achieved in strategies to regulate the Keap1-Nrf2 pathway, the availability of Nrf2 activators applicable to NDD is currently limited. Currently, the FDA has approved the Nrf2 activators dimethyl fumarate (DMF) and Omaveloxolone (Omav) as novel first-line oral drugs for the treatment of patients with relapsing forms of multiple sclerosis and Friedreich's ataxia. A promising alternative approach involves the direct inhibition of Keap1-Nrf2 protein-protein interactions (PPI), which offers numerous advantages over the use of electrophilic Nrf2 activators, primarily in avoiding off-target effects. This review examines the compelling evidence supporting the beneficial role of Nrf2 in NDD and explores the potential of Keap1 inhibitors and Keap1-Nrf2 PPI inhibitors as therapeutic agents, with the aim to provide further insights into the development of inhibitors targeting this pathway for the treatment of NDD.

Evaluation of the liver targeting and anti­liver cancer activity of artesunate­loaded and glycyrrhetinic acid­coated nanoparticles.

Globally, liver cancer ranks among the most lethal cancers, with chemotherapy being one of its primary treatments. However, poor selectivity, systemic toxicity, a narrow treatment window, low response rate and multidrug resistance limit its clinical application. Liver-targeted nanoparticles (NPs) exhibit excellent targeted delivery ability and promising effectivity in treating liver cancer. The present study aimed to investigate the liver-targeting and anti-liver cancer effect of artesunate (ART)-loaded and glycyrrhetinic acid (GA)-decorated polyethylene glycol (PEG)-poly (lactic-co-glycolic acid) (PLGA) (ART/GA-PEG-PLGA) NPs. GA-coated NPs significantly increased hepatoma-targeted cellular uptake, with micropinocytosis and caveolae-mediated endocytosis as its chief internalization pathways. Moreover, ART/GA-PEG-PLGA NPs exhibited pro-apoptotic effects on HepG2 cells, mainly via the induction of a high level of reactive oxygen species, decline in mitochondrial membrane potential and induction of cell cycle arrest. Additionally, ART/GA-PEG-PLGA NPs induced internal apoptosis pathways by upregulating the activity of cleaved caspase-3/7 and expression of cleaved poly (ADP-Ribose)-polymerase and Phos-p38 mitogen-activated protein kinase in HepG2 cells. Furthermore, ART/GA-PEG-PLGA NPs exhibited higher liver accumulation and longer mean retention time, resulting in increased bioavailability. Finally, ART/GA-PEG-PLGA NPs promoted the liver-targeting distribution of ART, increased the retention time and promoted its antitumour effects in vivo. Therefore, ART/GA-PEG-PLGA NPs afforded excellent hepatoma-targeted delivery and anti-liver cancer efficacy, and thus, they may be a promising strategy for treating liver cancer.

Design, Synthesis and Biological Evaluation of Glycosylated Derivatives of Silibinin as Potential Anti-Tumor Agents.

Objective: Silibinin, a natural product extracted from the seeds of the Silybum marianum, is versatile with various pharmacological effects. However, its clinical application was strongly hampered by its low bioavailability and poor water solubility. Herein, a series of glycosylated silibinin derivatives were identified as novel anti-tumor agents. Materials and Methods: The cell viability was evaluated by CCK8 assay. Furthermore, cell apoptosis and cell cycle progression were tested by flow cytometry. In addition, the pharmacokinetic assessment of compound 15 and silibinin through intravenous administration (i.v., 2 mg/kg) to ICR mice were performed. Results: The synthesized compounds showed better water solubilities than silibinin. Among them, compound 15 exhibited inhibitory activity against DU145 cells with IC50 value of 1.37 ± 0.140 µM. Moreover, it arrested cell cycle at G2/M phase and induced apoptosis in DU145 cells. Additionally, compound 15 also displayed longer half-life (T1/2 = 128.3 min) in liver microsomes than that of silibinin (T1/2 = 82.5 min) and appropriate pharmacokinetic parameters in mice. Conclusion: Overall, glycosylation of silibinin would be a valid strategy for the development of silibinin derivatives as anti-tumor agents.

pH-Responsive and liver-targeting drug delivery system for combination delivery of artesunate with arsenic trioxide prodrug against hepatocellular carcinoma.

OBJECTIVE: Arsenic trioxide (ATO) exerts therapeutic effects on various solid tumors, and artesunate (ART) synergizes with antitumor drugs. We herein combined ART and an ATO prodrug (ATOP) in pH-responsive and liver-targeting liposomes to improve targeted hepatocellular carcinoma (HCC) treatment. METHODS: 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine (DSPE)-hydrazone (HYD)-polyethylene glycol (PEG)-glycyrrhetinic acid (GA) (DSPE-HYD-PEG-GA) was synthesized and characterized. The optimal ratio of ART and ATOP was selected. Calcium arsenate nanoparticles (CaAs NPs) and DSPE-HYD-PEG-GA@ART/CaAs NPs liposomes were prepared and their physicochemical properties were characterized. Their intracellular uptake, intracellular localization, uptake pathway identification, cytotoxicity, proapoptotic effects, and relevant mechanisms were studied. RESULTS: The DSPE-HYD-PEG-GA was successfully synthesized. The best ratio of ART and ATOP was 7:1. The particle size of CaAs NPs under transmission electron microscopy was 142.39 ± 21.50 nm. Arsenic (As), calcium, and oxygen elements were uniformly distributed in CaAs NPs, and the drug loading and encapsulation efficiency of As are 37.28% and 51.40%, respectively. The liposomes were elliptical, and the particle size was 100.91 ± 39.31 nm. The liposome cell intake was significantly increased in Huh-7 cells. The liposomes entered the cell through macropinocytosis and caveolin-mediated endocytosis and were predominantly distributed in the cytoplasm. They exerted an excellent inhibitory effect on Huh-7 cells and promoted tumor cell apoptosis through lipid peroxidation, mitochondrial membrane potential reduction, and cell-cycle blockage. CONCLUSIONS: The pH-responsive and liver-targeting drug delivery system for the combination delivery of ART with ATOP showed promising effects on hepatocellular carcinoma (HCC).

Recent advances and future perspectives of noncompetitive proteasome inhibitors.

The proteasome regulates intracellular processes, maintains biological homeostasis, and has shown great significance in the study of various diseases, such as neurodegenerative diseases, immune-related diseases, and cancer, especially in hematologic malignancies such as multiple myeloma (MM) and mantle cell lymphoma (MCL). All clinically used proteasome inhibitors bind to the active site of the proteasome and thus exhibit a competitive mechanism. The development of resistance and intolerance during treatment drives the search for inhibitors with different mechanisms of action. In this review, we provide an overview of noncompetitive proteasome inhibitors, including their mechanisms of action, function, possible applications, and their advantages and disadvantages compared with competitive inhibitors.

Sequential [3+2] annulation reaction of prop-2-ynylsulfonium salts and hydrazonyl chlorides: synthesis of pyrazoles containing functional motifs.

A novel sequential [3+2] annulation reaction has been developed using prop-2-ynylsulfonium salts and hydrazonyl chlorides, affording a series of pyrazoles with functional motifs that can be post modified in the preparation of various drugs or drug candidates. Further transformation and gram-scale operations could also be achieved efficiently.

Regulation of Mitochondrial Function by Natural Products for the Treatment of Metabolic Associated Fatty Liver Disease.

Metabolic associated fatty liver disease (MAFLD) is a multifactorial systemic disorder that occurs in the absence of excessive alcohol consumption. The disease is characterized by fatty degeneration and fat accumulation in liver parenchymal cells, the incidence of which is increasing annually, particularly in younger adults. MAFLD is caused by genetic and metabolism related disorders, of which mitochondrial dysfunction is the major contributor. Natural products can relieve MAFLD through restoring mitochondrial function. In this article, we describe the relationship between mitochondria and MAFLD and discuss the beneficial effects of natural products as a future anti-MAFLD strategy. Significance Statement. We herein propose that the development of mitochondrial regulators/nutrients from natural products can remedy mitochondrial dysfunction which represents an attractive strategy for the treatment of MAFLD. Furthermore, the mitochondrial regulation of natural products can provide new insight into the underlying mechanisms of action of natural products used for future MAFLD therapeutics.

Optimization of piperidine constructed peptidyl derivatives as proteasome inhibitors.

A series of non-covalent piperidine-containing peptidyl derivatives with various substituents at side chains of different residues were designed, synthesized and evaluated as proteasome inhibitors. After proteasome inhibitory evaluations of all the synthesized target compounds, selected ones were tested for their anti-proliferation activities against three multiple myeloma (MM) cell lines. 8 analogues displayed more potent activities than carfilzomib, and the most promising compound 24 showed IC50 values of 0.8 ± 0.2 nM against 20S proteasome and 8.42 ± 0.74 nM, 7.14 ± 0.52 nM, 14.20 ± 1.08 nM for RPMI 8226, NCI-H929 and MM.1S cell lines, respectively. Additionally, mechanisms of anti-cancer activity of representative compound 24 were further investigated. Apoptosis of RPMI-8226 cells were achieved through accumulating polyubiquitin and inducing the cleavage of caspase and PARP. Besides, half-life in rat plasma of compound 24 was prolonged after optimization, which would be helpful for increasing in vivo activities of this series of derivatives. All the studies confirmed that piperidine-containing non-covalent proteasome inhibitors can be potential leads for anti-MM drug development.

Proteasome, a Promising Therapeutic Target for Multiple Diseases Beyond Cancer.

Proteasome is vital for intracellular protein homeostasis as it eliminates misfolded and damaged protein. Inhibition of proteasome has been validated as a powerful strategy for anti-cancer therapy, and several drugs have been approved for treatment of multiple myeloma. Recent studies indicate that proteasome has potent therapeutic effects on a variety of diseases besides cancer, including parasite infectious diseases, bacterial/fungal infections diseases, neurodegenerative diseases and autoimmune diseases. In this review, recent developments of proteasome inhibitors for various diseases and related structure activity relationships are going to be summarized.

Preparation, evaluation, and in vitro cytotoxicity studies of artesunate-loaded glycyrrhetinic acid decorated PEG-PLGA nanoparticles.

OBJECTIVE: The objective of this study was to prepare the liver targeting drug delivery system (TDDS) of artesunate (ART)-loaded polyethylene glycol (PEG)-poly(d,l-lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) modified by glycyrrhetinic acid (GA), and evaluate its in vitro cytotoxicity. SIGNIFICANCE: The GA-PEG-PLGA-ART NPs enhanced the in vitro cytotoxicity on HCC cell lines. The development of GA-PEG-PLGA NPs will greatly push the clinical applications of ART as a novel anticancer drug. METHODS: The NPs were prepared using solvent evaporation method, and the formulation was optimized through an orthogonal design. In addition, physical properties were determined, including particle size, polydispersity index (PDI), zeta potential (ZP), morphology, drug loading capacity (LC) and encapsulation efficiency (EE), and in vitro drug release. Moreover, the in vitro cytotoxicity of NPs with three human cancer cell lines viz. HepG2, Hep3B, and SMCC-7721 was conducted using the SRB assay. Additionally, lyophilization was conducted to improve the long-term physical stability. RESULTS: The GA-PEG-PLGA-ART NPs have spherical shape, small particle size (around 88 nm) with a narrow size distribution (PDI < 0.3), high drug LC (up to 59.3 ± 1.65%), and high EE (up to 73.13 ± 5.17%). In vitro drug release behavior showed that drugs were released from NPs in a sustained and controlled release pattern. Cytotoxicity study indicated the NPs achieved lower cancer cell survival fraction. The GA-PEG-PLGA NPs freeze-dried with 3% (w/v) of mannitol showed better effect on long-term physical stability. CONCLUSION: The GA-PEG-PLGA-ART NPs appear as a potential liver targeted intracellular delivery platform for ART.

Protective effect of apigenin magnesium complex on H2O2-induced oxidative stress and inflammatory responses in rat hepatic stellate cells.

Context: Apigenin displays antioxidant and anti-inflammatory effects. However, effects of apigenin magnesium (AM) complex on these aspects remain unknown.Objective: This study investigated the effects of AM complex on oxidative stress and inflammatory responses in hydrogen peroxide (H2O2)-induced rat hepatic stellate cells (HSCs).Materials and methods: The antioxidant and anti-inflammatory effects of AM complex at concentrations of 0.625, 1.25, and 2.5 mg/mL were evaluated, comparing to HSCs treated by H2O2 alone. Cell viability, reactive oxygen species (ROS), the activity of superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), nitric oxide (NO), interleukin 6 (IL-6), and nuclear factor-kappa B (NF-κB) levels were measured. Moreover, cell apoptosis, mRNA expression levels of transforming growth factor-ß (TGF-ß), NF-κB, and inducible nitric oxide synthase (iNOS) were assessed.Results: AM complex significantly inhibited oxidative stress and inflammatory response at concentrations of 0.625, 1.25, and 2.5 mg/mL (IC50 = 1.679 mg/mL). AM complex elevated the survival rate of H2O2-treated HSCs and had no toxic effects on HSCs. AM complex also promoted SOD activity and GSH levels but suppressed ROS, MDA, and NO levels. Additionally, AM complex decreased IL-6 and NF-κB levels, gene expression of TGF-ß, NF-κB, and iNOS, as well as induced apoptosis of HSCs.Discussion and conclusions: Data indicated that AM complex mitigated oxidative stress and inflammatory responses on H2O2-treated HSCs, suggesting that AM complex is a possible candidate for anti-hepatic diseases. Additional efforts, both in vivo and in humans, are required to assess of AM complex as a potential therapeutic drug in liver diseases.

Immunoproteasome-selective inhibitors: An overview of recent developments as potential drugs for hematologic malignancies and autoimmune diseases.

The immunoproteasome, a specialized form of proteasome, is mainly expressed in lymphocytes and monocytes of jawed vertebrates and responsible for the generation of antigenic peptides for cell-mediated immunity. Overexpression of immunoproteasome have been detected in a wide range of diseases including malignancies, autoimmune and inflammatory diseases. Following the successful approval of constitutive proteasome inhibitors bortezomib, carfilzomib and Ixazomib, and with the clarification of immunoproteasome crystal structure and functions, a variety of immunoproteasome inhibitors were discovered or rationally developed. Not only the inhibitory activities, the selectivities for immunoproteasome over constitutive proteasome are essential for the clinical potential of these analogues, which has been validated by the clinical evaluation of immunoproteasome-selective inhibitor KZR-616 for the treatment of systemic lupus erythematosus. In this review, structure, function as well as the current developments of various inhibitors against immunoproteasome are going to be summarized, which help to fully understand the target for drug discovery.

Design, synthesis, and biological evaluation of novel 3-(thiophen-2-ylthio)pyridine derivatives as potential multitarget anticancer agents.

A series of novel 3-(thiophen-2-ylthio)pyridine derivatives as insulin-like growth factor 1 receptor (IGF-1R) inhibitors was designed and synthesized. IGF-1R kinase inhibitory activities and cytotoxicities against HepG2 and WSU-DLCL2 cell lines were tested. For all of these compounds, potent cancer cell proliferation inhibitory activities were observed, but not through the inhibition of IGR-1R. Selected compounds were further screened against various kinases. Typical compound 22 (50% inhibitory concentration [IC50 ] values, HepG2: 2.98 ± 1.11 µM and WSU-DLCL2: 4.34 ± 0.84 µM) exhibited good inhibitory activities against fibroblast growth factor receptor-2 (FGFR2), FGFR3, epidermal growth factor receptor, Janus kinase, and RON (receptor originated from Nantes), with IC50 values ranging from 2.14 to 12.20 µM. Additionally, the cell-cycle analysis showed that compound 22 could arrest HepG2 cells in the G1/G0 phase. Taken together, all the experiments confirmed that the compounds in this series were multitarget anticancer agents worth further optimizing.

Protective effect of N-acetylcysteine activated carbon release microcapsule on myocardial ischemia-reperfusion injury in rats.

With the development of science and technology, and development of artery bypass, methods such as cardiopulmonary cerebral resuscitation have been practiced in recent years. Despite this, some methods fail to promote or recover the function of tissues and organs, and in some cases, may aggravate dysfunction and structural damage to tissues. The latter is typical of ischemia-reperfusion (IR) injury. Lipid peroxidation mediated by free radicals is an important process of myocardial IR injury. Myocardial IR has been demonstrated to induce the formation of large numbers of free radicals in rats, which promotes the peroxidation of lipids within unsaturated fatty acids in the myocardial cell membrane. Markers of lipid peroxidation include malondialdehyde, superoxide dismutase and lactic dehydrogenase. Recent studies have demonstrated that N-acetylcysteine (NAC) is able to dilate blood vessels, prevent oxidative damage, improve immunity, inhibit apoptosis and the inflammatory response and promote glutathione synthesis in cells. NAC also improves the systolic function of myocardial cells and cardiac function, prevents myocardial apoptosis, protects ventricular remodeling and vascular remodeling, reduces opiomelanocortin levels in the serum and increases the content of nitric oxide in the serum, thus improving vascular endothelial function. Therefore, NAC has potent pharmacological activity; however, the relatively fast metabolism of NAC, along with its large clinical dose and low bioavailability, limit its applications. The present study combined NAC with medicinal activated carbons, and prepared N-acetylcysteine activated carbon sustained-release microcapsules (ACNACs) to overcome the limitations of NAC. It was demonstrated that ACNACs exerted greater effective protective effects than NAC alone on myocardial IR injury in rats.

Activated carbon N-acetylcysteine microcapsule protects against nonalcoholic fatty liver disease in young rats via activating telomerase and inhibiting apoptosis.

Non-alcoholic fatty liver disease (NAFLD) is becoming one of the world's most common chronic liver diseases in childhood, yet no therapy is available that has been approved by the food and drug administration (FDA). Previous studies have reported that telomere and telomerase are involved the development and progression of NAFLD. This study was designed to investigate the potential beneficial effects of activated carbon N-acetylcysteine (ACNAC) microcapsules on the development of NAFLD in young rats as well as the underlying mechanism(s) involved. Three-week old male Sprague Dawley rats were given high-fat diet (HFD) with/without ACNAC treatment for 7 consecutive weeks. Liver pathologies were determined by hematoxylin and eosin (H&E) and Oil Red O staining, as well as by changes in biochemical parameters of plasma alanine transaminase (ALT) and aspartate transaminase (AST) levels, respectively. Glucose homeostasis was evaluated by the glucose tolerance test and the liver telomere length and activity were measured by real time PCR and telomeric repeat amplification protocol (TRAP). Western blot analysis was performed to determine the expression level of Bcl-2, Bax and Caspase-3. Our results demonstrated that ACNAC supplementation improved liver pathologies of rats that received long-term HFD feeding. ACNAC supplementation prevented HFD-induced telomere shortening and improved telomerase activity. Moreover, in comparison to HFD-fed rats, ACNAC supplementation markedly increased the expression of Bcl-2, but significantly decreased the expression of Bax and Caspase-3 in juvenile rats. Together, these results indicate that ACNAC may be a promising choice for preventing and treating NAFLD among children.

N,N'-diacetylcystine ameliorates inflammation in experimental non-alcoholic steatohepatitis by regulating nuclear transcription factor kappa B activation.

Non-alcoholic fatty liver disease (NAFLD) is one of the most common diseases worldwide that has been continuously increasing recently. NAFLD embraces a spectrum of liver histological alterations, ranging from simple steatosis (NAFL) to severe non-alcoholic steatohepatitis (NASH), that is characterized by fat accumulation, lobular inflammation, and ballooning degeneration in the hepatocytes in the absence of alcohol abuse. The innate immune system has an important role in NASH pathogenesis. Among the components of innate immunity, the nuclear factor kappa B (NF-κB) has been closely associated with NASH. N,N'-diacetylcystine (DiNAC), the disulfide dimer of N-acetylcysteine (NAC), is a potent modulator of the immune system. Previous research has confirmed that DiNAC has beneficial effects in liver injury. In this study, we aimed to investigate the effects of DiNAC on high fat diet (HFD)-induced NASH in rats. Male Sprague-Dawley rats were fed with HFD to produce the NASH model and treated with or without DiNAC for 8 weeks. We assessed serum levels of alanine-aminotransferase (ALT), aspartate aminotransferase (AST), inflammatory cytokines, liver histology, and the expression of NF-κB genes in the liver. The results showed that the levels of ALT and AST were significantly increased in the HFD rat model. DiNAC treatment also resulted in a statistically significant reduction of the levels of ALT and AST. Hematoxylin and eosin (H&E) staining revealed that DiNAC alleviated histological injury. Moreover, DiNAC strongly reduced the generation of inflammatory cytokines, such as interleukin-6 (IL-6), tumor necrosis factor α (TNF-α) and interleukin-1ß (IL-1ß), through NF-κB downregulation. Taken together, these results indicate that DiNAC treatment effectively delayed the progression of NASH by suppressing the expression of NF-κB mRNA in the liver. Our data suggest that DiNAC protects liver injury in HFD-treated NASH rats, which might be a promising drug for the treatment of NASH.

Effects of activated carbon N-acetylcysteine sustained-release microcapsule on dipeptidyl peptidase IV expression in young rats with non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) in children has become the most common liver disease influencing adolescent health and one of the most influencing chronic liver diseases among children in Chinese wealthy families, particularly in coastal regions. However, the medicine available for the treatment of NAFLD is deficient. In order to solve this problem, our team studied the activated carbon N-acetylcysteine (NAC) sustained-release microcapsule, which improves the oxidation resistance, bioavailability and drug stability of acetylcysteine and reduces toxic and side effects. In addition, it accords with the characteristics of medication in infants and children. The present study mainly discusses whether the activated carbon NAC sustained-release microcapsule has effects on dipeptidyl peptidase IV (DPPIV) activity and protein in young rats with NAFLD, and whether it has the effect of an DPPIV inhibitor, hoping to provide new thoughts and methods with respect of basic studies on young rats with NAFLD/non-alcoholic steatohepatitis.