Endogenous chemicals guard health through inhibiting ferroptotic cell death.

Ferroptosis is a new form of regulated cell death caused by iron-dependent accumulation of lethal polyunsaturated phospholipids peroxidation. It has received considerable attention owing to its putative involvement in a wide range of pathophysiological processes such as organ injury, cardiac ischemia/reperfusion, degenerative disease and its prevalence in plants, invertebrates, yeasts, bacteria, and archaea. To counter ferroptosis, living organisms have evolved a myriad of intrinsic efficient defense systems, such as cyst(e)ine-glutathione-glutathione peroxidase 4 system (cyst(e)ine-GPX4 system), guanosine triphosphate cyclohydrolase 1/tetrahydrobiopterin (BH4) system (GCH1/BH4 system), ferroptosis suppressor protein 1/coenzyme Q10 system (FSP1/CoQ10 system), and so forth. Among these, GPX4 serves as the only enzymatic protection system through the reduction of lipid hydroperoxides, while other defense systems ultimately rely on small compounds to scavenge lipid radicals and prevent ferroptotic cell death. In this article, we systematically summarize the chemical biology of lipid radical trapping process by endogenous chemicals, such as coenzyme Q10 (CoQ10), BH4, hydropersulfides, vitamin K, vitamin E, 7-dehydrocholesterol, with the aim of guiding the discovery of novel ferroptosis inhibitors.

Design, synthesis, and biological evaluation of 2-amino-6-methyl-phenol derivatives targeting lipid peroxidation with potent anti-ferroptotic activities.

The suppression of ferroptosis is emerging as a promising therapeutic strategy for effectively treating a wide range of diseases, including neurodegenerative disorders, organ ischemia-reperfusion injury, and inflammatory conditions. However, the clinical utility of ferroptosis inhibitors is significantly impeded by the limited availability of rational drug designs. In our previous study, we successfully unraveled the efficacy of ferrostatin-1 (Fer-1) attributed to the synergistic effect of its ortho-diamine (-NH) moiety. In this study, we present the discovery of the ortho-hydroxyl-amino moiety as a novel scaffold for ferroptosis inhibitors, employing quantum chemistry as well as in vitro and in vivo assays. 2-amino-6-methylphenol derivatives demonstrated remarkable inhibition of RSL3-induced ferroptosis, exhibiting EC50 values ranging from 25 nM to 207 nM. These compounds do not appear to modulate iron homeostasis or lipid reactive oxygen species (ROS) generation pathways. Nevertheless, they effectively prevent the accumulation of lipid peroxides in living cells. Furthermore, compound 13 exhibits good in vivo activities as it effectively protect mice from kidney ischemia-reperfusion injury. In summary, compound 13 has been identified as a potent ferroptosis inhibitor, warranting further investigation as a promising lead compound.

Transcriptional regulation of the fidaxomicin gene cluster and cellular development in Actinoplanes deccanensis YP-1 by the pleiotropic regulator MtrA.

IMPORTANCE: Cascade regulation networks are almost present in various kinds of microorganisms, but locating and systematically elucidating specific pleiotropic regulators related to a certain gene cluster can be a tricky problem. Here, based on the promoter of the fidaxomicin pathway-specific regulator FadR1, we utilized a "DNA to Proteins" affinity purification method and captured a global regulator MtrA, which positively regulates fidaxomicin biosynthesis. In the mtrA overexpressed strain, the production of fidaxomicin was improved by 37% compared to the native strain. Then, we combined the "Protein to DNAs" affinity purification method (DAP-seq) with the results of RNA-seq and systematically elucidated the primary and secondary metabolic processes in which MtrA directly or indirectly participates. Thus, our work brought up a new way to improve fidaxomicin production from the perspective of global regulation and analyzed the regulatory mechanism of MtrA. Meanwhile, we provided a novel methodology for the research of cascade regulation networks and vital secondary metabolites.

Transarterial Chemoembolization Plus Lenvatinib and PD-1 Inhibitors for Hepatocellular Carcinoma with Main Trunk Portal Vein Tumor Thrombus: A Multicenter Retrospective Study.

Purpose: In recent years, immune checkpoint inhibitors have been used in combination with tyrosine kinase inhibitors and local therapies, creating a new era in treating hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT). However, the benefits of this triple therapy remain unclear. Thus, this study evaluated whether the combination of transarterial chemoembolization (TACE), lenvatinib, and programmed death-1 (PD-1) inhibitors (triple therapy) was effective and safe for unresectable HCC with main trunk portal vein tumor thrombus (Vp4). Patients and Methods: This study enrolled patients receiving triple therapy at four institutions between August 2018 and April 2022. Patient characteristics and course of treatment were extracted from patient records. Tumors and tumor thrombus response were evaluated using an HCC-specific modified RECIST. Kaplan-Meier curve analysis demonstrated overall survival (OS) and progression-free survival (PFS). Adverse events (AEs) were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. Results: Median follow-up duration was 18 (4.0-26.3) months. Overall, 41 patients with HCC and Vp4 receiving first-line triple therapy were enrolled. The intrahepatic tumor objective response rate was 68.3%. The median OS was 21.7 (range, 2.8-30.5) months, whereas the median PFS was 14.5 (range, 1.3-27.6) months. Twelve patients received sequential resections. Resection was independently associated with favorable OS and PFS. Fever (31.7%), hypertension (26.8%), fatigue (24.4%), abnormal liver function (63.4%) and decreased appetite (21.9%) were the AEs frequently associated with treatment. No treatment-related mortality occurred. Conclusion: TACE plus lenvatinib and PD-1 inhibition was effective and tolerable for treating unresectable HCC with Vp4, with a high tumor response rate and favorable prognosis.

Aroma formation and transformation during sealed yellowing process of Pingyang yellow tea.

Yellow tea, a unique type of tea in China which is characterized with yellow color, has gained increasing popularity due to its pleasant taste. However, transformation of aroma compounds during sealed yellowing has been poorly understood. Results of sensory evaluation exhibited that yellowing time was the key factor for flavor and fragrance formation. A total of 52 volatile components during sealed yellowing process of Pingyang yellow soup were further collected and analyzed. The results demonstrated that the sealed yellowing process significantly increased the ratio of alcohol and aldehyde compounds in the aroma volatiles of yellow tea, which were primarily composed of geraniol, linalool, phenylacetaldehyde, linalool oxide and cis-3-hexenol, and their proportion increased with the prolongation of sealed yellowing. Mechanistic speculation revealed that the sealed yellowing process promoted release of alcoholic aroma compounds from their glycoside precursors and enhanced Strecker and oxidative degradation. This study revealed the transformation mechanism of aroma profile during the sealed yellowing process, which would facilitate processing of yellow tea.

Hot Deformation and Constitutive Modeling of TC21 Titanium Alloy.

Titanium alloys are extensively employed in the fabrication of various aviation structural parts, of which the most crucial processing step is hot working. In order to study the high-temperature deformation behavior of the TC21 titanium alloy, high-temperature tensile tests were performed. The results reveal that the flow stress of the material gradually decreases with an increased strain rate, and the stress increases rapidly with an increase in strain during the deformation of the alloy. Following this, flow stress gradually decreases. Flow stress decreases sharply, and the sample fractures when the appearance of necking and microvoids is observed. The Arrhenius and Radial basis function (RBF) neural network constitutive models are established in order to accurately describe the high-temperature deformation behavior of the material. In the modified Arrhenius model, strain rate indexes are expressed as a function of deformation temperature and strain rates; furthermore, the high prediction ability of the model was obtained. For the Radial basis function, the network parameters were obtained using the trial-and-error method. The established models could better forecast the flow stress of materials, and highly accurate results are obtained using the radial basis function model. The relationships between the stress index and the deformation activation energy with strain indicate that the primary deformation mechanism involves grain boundary slip and viscous slip of dislocations. The process of dynamic recrystallization primarily promotes the softening of the material.

Hsa_circRNA_100146 Promotes Prostate Cancer Progression by Upregulating TRIP13 via Sponging miR-615-5p.

Objective: This study was conducted for investigating the functions of circular RNA circRNA_100146 (circRNA_100146) in the development of prostate cancer (PCa) and identifying the underlying mechanisms of the circRNA_100146/miR-615-5p/TRIP13 axis. Materials and Methods: Under the support of RT-PCR, the expression of circRNA_100146 in PCa cells was examined. Cell Counting Kit-8 (CCK-8) assays and clone formation assays were applied to the assessment of cell proliferation. We then determined cell invasion and migration through transwell assays and wound healing assays. RNA pull-down assays and luciferase reporter assays were performed for the exploration of the regulatory effects of potential molecules on the expressions of the targeting genes. In addition, a nude mouse xenograft model was applied to demonstrate the oncogenic roles of circRNA_100146 in PCa. Results: CircRNA_100146 expression was distinctly upregulated in PCa cells. Silencing of circRNA_100146 suppressed PCa cells' invasion, migration, and proliferation. CircRNA_100146 sponged miR-615-5p to suppress its expressions, while miR-615-5p targeted the 3'-UTR of TRIP13 to repress the expression of TRIP13. In addition, we observed that knockdown of miR-615-5p reversed the suppression of circRNA_100146 silence on the proliferation and invasion of PCa cells. In addition, the tumor growth was also suppressed by silencing circRNA_100146 in vivo. Conclusion: CircRNA_100146 is a tumor promoter in PCa, which promoted progression by mediating the miR-615-5p/TRIP13. CircRNA_100146 can be a potential candidate for targeted therapy of PCa.

Rational engineering strategies for achieving high-yield, high-quality and high-stability of natural product production in actinomycetes.

Actinomycetes are recognized as excellent producers of microbial natural products, which have a wide range of applications, especially in medicine, agriculture and stockbreeding. The three main indexes of industrialization (titer, purity and stability) must be taken into overall consideration in the manufacturing process of natural products. Over the past decades, synthetic biology techniques have expedited the development of industrially competitive strains with excellent performances. Here, we summarize various rational engineering strategies for upgrading the performance of industrial actinomycetes, which include enhancing the yield of natural products, eliminating the by-products and improving the genetic stability of engineered strains. Furthermore, the current challenges and future perspectives for optimizing the industrial strains more systematically through combinatorial engineering strategies are also discussed.

Genome-based rational engineering of Actinoplanes deccanensis for improving fidaxomicin production and genetic stability.

Microbial fermentation is currently still the major way to produce structural complicated clinical drugs. Yet, the low productivity and genetic instability of producing strains remain the bottlenecks in microbial pharmaceutical industry. Fidaxomicin is a microbial drug against the Clostridium difficile infection. Here, a genome-based combinatorial engineering strategy was established to improve both fidaxomicin production and the genetic stability of Actinoplanes deccanensis YP-1. Guided by genomic analysis, several genetic instability-associated elements were cumulatively deleted, generating a more genetically stable mutant. Further rational engineering approaches including elimination of a pigment pathway, duplication of the fidaxomicin gene cluster, overexpression of a positive regulator and optimization of the fermentation medium, led to an overall 27-folds improvement in fidaxomicin production. Taken together, the genome-based rational combinatorial engineering strategy was efficient to enhance the fidaxomicin production and ameliorate the genetic stability of YP-1, it can also be widely used in other industrial actinomycetes for strain improvement.

Theoretical Insights into the Cotransport Mechanism of GSH with Anticancer Drugs by MRP1.

The multidrug resistance protein MRP1 is an ATP binding cassette (ABC) transporter that confers resistance to many anticancer drugs and regulates redox homeostasis, inflammation, and hormone secretion. MRP1 actively transports compounds across cell membranes, and the presence of glutathione (GSH) is required in many cases. However, the process of MRP1-mediated substrate transportation has been poorly understood. With extensive molecular dynamics simulations, we have found a sandwich-like structure which is generated by GSH, a transmembrane α-helices 11 (TM11)-TM17 axis, and anticancer drugs. This structure is crucial in MRP1 transportation. It triggers the motion of TM11 and TM17, followed by the movement of nucleotide-binding domains 1 (NBD1) and 2 (NBD2), and finally an occluded structure is formed. Trp1246, Lys332, and Phe594 were identified as the main contributors in the formation of the sandwich-like structure. Our findings clearly explain the synergy of GSH with an anticancer drug in MRP1 transportation and have significant meanings for the rational design of novel inhibitors against MRP1.

Anticancer effects of Mahanimbine alkaloid on the human bladder cancer cells are due to the induction of G0/G1 cell cycle arrest, apoptosis and autophagy.

PURPOSE: The main purpose of the current research work was to investigate the anticancer effects of Mahanimbine alkaloid in human bladder cancer cells along with examining its effects on cellular apoptosis, cell cycle phase distribution, and cell autophagy. METHODS: Cell viability was examined by WST-1 cell viability assay. Mahanimbine-induced apoptosis was examined by fluorescent microscopy using acridine orange (AO)/ethidium bromide (EB) staining as well as using flow cytometry in combination with annexin-v/propidium iodide (PI) staining. Further, western blot assay was used to study the effects of Mahanimbine on apoptosis-related protein expressions including Bax and Bcl-2. Autophagy induction was evaluated by transmission electron microscopy (TEM) and western blot. Flow cytometry was used to study the effects on cell cycle. RESULTS: The results showed that Mahanimbine decreased the viability of the human bladder cancer cells and exhibited an IC50 of 32.5 µM. The test molecule also caused remarkable changes in the morphology of human bladder cancer cells and inhibited their colony forming potential. The AO/EB staining assay showed that Mahanimbine inhibits the viability of cancer cells via induction of apoptotic cell death which was associated with increase in Bax and decrease in Bcl-2 levels. The apoptotic cells increased from 5.2% in control to around 75% at 100 µM concentration. Mahanimbine also led to dose-dependent G0/G1 cell cycle arrest. Autophagic vacuoles appeared in the treated cells indicating autophagic induction by the test molecule. The Mahanimbine-triggered autophagy was also linked with increase in the expression of LC3II and decrease in p62 expression. However, no apparent effects were observed on the LC3 I expression. CONCLUSION: Taken together, the results of this study indicate that Mahanimbine natural product has the potential to be developed as a promising anticancer agent against human bladder carcinoma but further studies are needed to this direction.

The increase of osteopontin and ß-carboxy-terminal cross-linking telopeptide of type I collagen enhances the risk of hip fracture in the elderly.

BACKGROUND: Hip fracture in the elderly is a health burden worldwide due to its high mortality rate. This study was conducted to determine the possible mechanisms of osteopontin (OPN) and ß-carboxy-terminal cross-linking telopeptide of type I collagen (ß-CTX) in hip fracture in the elderly. MATERIALS AND METHODS: In the study, we recruited 108 elderly patients with hip fracture diagnosed from May 2012 to May 2015 at the Third Hospital of Xiamen and 86 healthy individuals without a history of hip fracture were taken as controls. Serum levels of OPN and ß-CTX were then determined. The T and Z values for bone mineral density (BMD) were also measured. Moreover, logistic regression analysis was performed to assess the risk and protective factors for hip fracture in the elderly. RESULTS: Serum levels of both OPN and ß-CTX were increased in elderly patients with hip fracture. OPN was positively correlated with ß-CTX. In addition, the levels of OPN and ß-CTX shared a positive association with the age, and a negative association with the BMD, in terms of T and Z values of the hip. In addition, increased BMD and outdoor sports might be protective factors for hip fracture, and an increase in levels of OPN and ß-CTX might be associated with a higher risk of hip fracture in the elderly population. DISCUSSION: Collectively, increased serum levels of OPN and ß-CTX might be correlated with a higher risk of a hip fracture and have predictive values in the occurrence of hip fracture in the elderly.

Comprehensive dissection of dispensable genomic regions in Streptomyces based on comparative analysis approach.

BACKGROUND: Large-scale genome reduction has been performed to significantly improve the performance of microbial chassis. Identification of the essential or dispensable genes is pivotal for genome reduction to avoid synthetic lethality. Here, taking Streptomyces as an example, we developed a combinatorial strategy for systematic identification of large and dispensable genomic regions in Streptomyces based on multi-omics approaches. RESULTS: Phylogenetic tree analysis revealed that the model strains including S. coelicolor A3(2), S. albus J1074 and S. avermitilis MA-4680 were preferred reference for comparative analysis of candidate genomes. Multiple genome alignment suggested that the Streptomyces genomes embodied highly conserved core region and variable sub-telomeric regions, and may present symmetric or asymmetric structure. Pan-genome and functional genome analyses showed that most conserved genes responsible for the fundamental functions of cell viability were concentrated in the core region and the vast majority of abundant genes were dispersed in the sub-telomeric regions. These results suggested that large-scale deletion can be performed in sub-telomeric regions to greatly streamline the Streptomyces genomes for developing versatile chassis. CONCLUSIONS: The integrative approach of comparative genomics, functional genomics and pan-genomics can not only be applied to perform a multi-tiered dissection for Streptomyces genomes, but also work as a universal method for systematic analysis of removable regions in other microbial hosts in order to generate more miscellaneous and versatile chassis with minimized genome for drug discovery.

Theoretical insight into the multiple interactions of quinazoline inhibitors with breast cancer resistance protein (BCRP/ABCG2).

Communicated by Ramaswamy H. Sarma.

Fragment-centric topographic mapping method guides the understanding of ABCG2-inhibitor interactions.

Understanding protein-ligand interactions is crucial to drug discovery and design. However, it would be extremely difficult for the proteins which only have one available apo structure but multiple binding sites. To address this constraint, a fragment-centric topographic mapping method (AlphaSpace software) was employed to map out concave interaction pockets at the assigned protein region. These pockets are used as complementary spaces to screen the known inhibitors for this specific binding site and to guide the molecular docking pose selection as well as protein-ligand interaction analysis. By mapping the shape of central cavity surface, we have tested the strategy against a multi-drug resistant transmembrane protein-ABCG2 to assist in generating a pharmacophore model for its inhibitors that is based on the structure of apo. Classical molecular simulation and accelerated molecular simulation are used to verify the accuracy of inhibitor screening and binding pose selection. Our study not only has gained insight for the development of novel specific ABCG2 inhibitors, but also has provided a general strategy in describing protein-ligand interactions.

Reactions of the Lipid Hydroperoxides With Aminic Antioxidants: The Influence of Stereoelectronic and Resonance Effects on Hydrogen Atom Transfer.

Aminic radical-trapping antioxidants (RTAs), as one of the most important antioxidants, have not received sufficient attention yet. But, an increasing number of aminic RTAs have been identified as ferroptosis inhibitors in recent years, which can potentially mediate many pathological states including inflammation, cancer, neurodegenerative disease, as well as ocular and kidney degeneration. This highlights the importance of aminic RTAs in the field of medicine. Herein, we systematically explored the radical scavenging mechanism of aminic RTAs with a quantum chemical method, particularly emphasizing the role of stereoelectronic factors and resonance factors on the transfer of H-atom and the stability to one-electron oxidation. These theoretical results elucidate the diversity of free radical scavenging mechanisms for aminic RTAs, and has significant implications for the rational design of new aminic RTAs.

Inhibition of endogenous hydrogen sulfide production exacerbates the inflammatory response during urine-derived sepsis-induced kidney injury.

The aim of the present study was to investigate the effects of endogenous H2S on the inflammatory response in kidneys following urine-derived sepsis-induced injury. A rabbit model of urine-derived sepsis was established by injecting Escherichia coli into the ligated ureter. Rabbits were randomly divided into the, control, sham, sepsis and DL-propargylglycine (PAG)-treated sepsis groups. The same surgical procedure except for the bacteria injection was performed for the sham group, while the control group was fed on normal diet without any additional treatments. The monitoring of vital signs, routine blood examinations and kidney function tests were performed prior to surgery and at 12, 24, 36 and 48 h following surgery. The serum H2S concentration and kidney cystathionine-γ-lyase (CSE) activity were determined following surgery. Pathological alterations were assessed by hematoxylin and eosin (H&E) staining, and the expression levels of inflammation-associated cytokines were detected by western blot analysis. The results demonstrated that rabbits in the sepsis and PAG groups exhibited a significant increase in rectal temperature, heart rate and respiratory rate following surgery when compared with the sham group; with the PAG group demonstrating the greatest increase. In addition, white cell counts and creatinine and urea nitrogen levels were significantly elevated following surgery in the sepsis and PAG groups when compared with the sham group. The serum H2S concentration and kidney CSE activity were significantly reduced in the sepsis group compared with the sham group, and a significant decrease in the levels of these factors were observed in the PAG group compared with the sepsis group. H&E staining indicated obvious structural abnormalities in kidney tissues in the sepsis group, which were exacerbated by PAG treatment. In addition, PAG treatment significantly increased the expression levels of nuclear factor-κB and interleukin-6, and decreased transforming growth factor-ß1 expression when compared with the sepsis group. In conclusion, PAG significantly exacerbated urine-derived sepsis-induced kidney injury potentially via altering the expression of inflammation-associated cytokines.

Correction: Chiral ruthenium polypyridyl complexes as mitochondria-targeted apoptosis inducers.

[This corrects the article DOI: 10.1039/C0MD00060D.].

O-Phenylenediamine: a privileged pharmacophore of ferrostatins for radical-trapping reactivity in blocking ferroptosis.

Ferroptosis is a non-apoptotic, iron dependent form of regulated cell death that is characterized by the accumulation of lipid hydroperoxides. It has drawn considerable attention owing to its putative involvement in diverse neurodegenerative diseases. Ferrostatins are the first identified inhibitors of ferroptosis and they inhibit ferroptosis by efficiently scavenging free radicals in lipid bilayers. However, their further medicinal application has been limited due to the deficient knowledge of the lipid peroxyl radical-trapping mechanism. In this study, experimental and theoretical methods were performed to illustrate the possible lipid hydroperoxide inhibition mechanism of ferrostatins. The results show that an ortho-amine (-NH) moiety from ferrostatins can simultaneously interact with lipid radicals, and then form a planar seven-membered ring in the transition state, and finally present greater reactivity. NBO analysis shows that the formed planar seven-membered ring forces ortho-amines into better alignment with the aromatic π-system. It significantly increases the magnitudes of amine conjugation and improves spin delocalization in the transition state. Additionally, a classical H-bond type interaction was discovered between a radical and an o-NH group as another transition state stabilizing effect. This type of radical-trapping mechanism is novel and has not been found in diphenylamine or traditional polyphenol antioxidants. It can be said that o-phenylenediamine is a privileged pharmacophore for the design and development of ferroptosis inhibitors.

Solvent Mediating a Switch in the Mechanism for Rhodium(III)-Catalyzed Carboamination/Cyclopropanation Reactions between N-Enoxyphthalimides and Alkenes.

Recently, a new synthetic methodology of rhodium-catalyzed carboamination/cyclopropanation from the same starting materials at different reaction conditions has been reported. It provides an efficient strategy for the stereospecific formation of both carbon- and nitrogen-based functionalities across an alkene. Herein we carried out a detailed theoretical mechanistic exploration for the reactions to elucidate the switch between carboamination and cyclopropanation as well as the origin of the chemoselectivity. Instead of the experimentally proposed RhIII-RhI-RhIII catalytic mechanism, our results reveal that the RhIII-RhV-RhIII mechanism is much more favorable in the two reactions. The chemoselectivity is attributed to a combination of electronic and steric effects in the reductive elimination step. The interactions between alkene and the rhodacycle during the alkene migration insertion control the stereoselectivity in the carboamination reactions. The present results disclose a dual role of the methanol solvent in controlling the chemoselectivity.