Photoswitchable PROTACs for Reversible and Spatiotemporal Regulation of NAMPT and NAD.

Nicotinamide adenine dinucleotide (NAD+ ) is an essential coenzyme with diverse biological functions in DNA synthesis. Nicotinamide phosphoribosyltransferase (NAMPT) is a key rate-limiting enzyme involved in NAD+ biosynthesis in mammals. We developed the first chemical tool for optical control of NAMPT and NAD+ in biological systems using photoswitchable proteolysis-targeting chimeras (PS-PROTACs). An NAMPT activator and dimethylpyrazolazobenzene photoswitch were used to design highly efficient PS-PROTACs, enabling up- and down-reversible regulation of NAMPT and NAD+ in a light-dependent manner and reducing the toxicity associated with inhibitor-based PS-PROTACs. PS-PROTAC was activated under 620 nm irradiation, realizing in vivo optical manipulation of antitumor activity, NAMPT, and NAD+ .

Research progress on the mechanism of intestinal barrier damage and drug therapy in a high altitude environment.

The plateau is a typical extreme environment with low temperature, low oxygen and high ultraviolet rays. The integrity of the intestinal barrier is the basis for the functioning of the intestine, which plays an important role in absorbing nutrients, maintaining the balance of intestinal flora, and blocking the invasion of toxins. Currently, there is increasing evidence that high altitude environments can enhance intestinal permeability and disrupt intestinal barrier integrity. This article mainly focuses on the regulation of the expression of HIF and tight junction proteins in the high altitude environment, which promotes the release of pro-inflammatory factors, especially the imbalance of intestinal flora caused by the high altitude environment. The mechanism of intestinal barrier damage and the drugs to protect the intestinal barrier are reviewed. Studying the mechanism of intestinal barrier damage in high altitude environment is not only conducive to understanding the mechanism of high altitude environment affecting intestinal barrier function, but also provides a more scientific medicine treatment method for intestinal damage caused by the special high altitude environment.

Discovery of Highly Potent Nicotinamide Phosphoribosyltransferase Degraders for Efficient Treatment of Ovarian Cancer.

Nicotinamide phosphoribosyltransferase (NAMPT) is identified as a promising target for cancer therapy. However, known NAMPT inhibitors are characterized by weak clinical efficacy and dose-dependent toxicity. There is an urgent need to develop new NAMPT intervention strategies. Using the proteolysis-targeting chimera (PROTAC) technology, we designed and synthesized a series of new von Hippel-Lindau (VHL)-recruiting NAMPT-targeting PROTACs. A highly potent NAMPT degrader (B3) was successfully identified, which displayed excellent degradation activity (DC50 < 0.17 nM, Dmax > 90%) and antiproliferative potency against A2780 cells (IC50 = 1.5 nM). PROTAC B3 induced NAMPT depletion in a concentration- and time-dependent manner through the ubiquitin-proteasome system. Particularly, PROTAC B3 achieved good plasma exposure levels via intravenous injection, gained potent tumor growth inhibition (TGI = 88.1%, 2 µM/kg) in the xenograft model, and demonstrated good biosafety without undesired toxicities. This study provides a highly potent VHL-recruiting NAMPT degrader for the treatment of ovarian cancer.

Protective effect of heme chloride on hypoxia-induced tissue injury in mice. / æ°¯åŒ–è¡€çº¢ç´ å¯¹ç¼ºæ°§å¯¼è‡´å°é¼ ç»„ç»‡æŸä¼¤çš„ä¿æŠ¤ä½œç”¨.

OBJECTIVES: Heme chloride (Hemin) is an in vitro purified form of natural heme and an important raw material for anti-anemia and antitumor drugs. This study aims to analyze the protective effect of Hemin on tissue damage in low-pressure oxygen chamber simulated plateau hypoxic mice, and explore its role in anti-plateau hypoxia. METHODS: Thirty male BALB/c mice were randomly divided into a blank group, a positive drug group (acetazolomide, 200 mg/kg), a Hemin low-dose group (15 mg/kg), a Hemin medium-dose group (30 mg/kg), and a Hemin high-dose group (60 mg/kg) with intraperitoneal injection. The anti-hypoxic activity of Hemin was explored by atmospheric closed hypoxia experiment and the optimal dose was screened. Thirty-six male BALB/c mice were randomly divided into a blank group, a hypoxia group, a positive drug group, and a Hemin high-dose group. The plasma inflammatory factor levels and oxidative stress indicators malondialdehyde (MDA), glutataione (GSH), and superoxide dismutase (SOD) levels of myocardium, brain, lung, and liver tissues were measured in different groups with hypoxia for 24 h. The degree of histopathological damage of mice was observed with HE staining. The degree of protection of Hemin against tissue hypoxia injury was detected with the hypoxia probe piperidazole. RESULTS: Compared with the blank group, the survival time of mice in the positive drug group, the Hemin medium-dose group, and high-dose group was significantly extended (all P<0.05), with the highest prolongation rate in the Hemin high-dose group. Compared with the hypoxia group, mice in the Hemin high-dose group showed a significant increase in SOD level and GSH content of brain tissue, and a significant decrease in MDA content of lung tissue (all P<0.05). The results of HE staining and hypoxia probe showed that Hemin had a significant protective effect on the damage of liver, heart, brain and lung tissues of mice with hypoxia, and the most obvious effect on that of the brain tissue. CONCLUSIONS: Hemin has an effect of improvement on oxidative stress and inflammatory response caused by hypoxia, and has obvious protective effect on tissue damage caused by hypoxia.

Making Protein Degradation Visible: Discovery of Theranostic PROTACs for Detecting and Degrading NAMPT.

Proteolysis-targeting chimera (PROTAC) is emerging as a promising technology in targeted protein degradation and drug discovery. However, there is still a lack of effective chemical tools to real-time detect and track the protein degradation. Herein, the first fluorescent and theranostic PROTACs were designed for imaging the degradation of nicotinamide phosphoribosyltransferase (NAMPT) in living cells. Compound B4 was proven to be an environmentally sensitive fluorescent PROTAC, which efficiently degraded NAMPT (DC50 = 8.4 nM) and enabled the visualization of degradation in A2780 cells. As a theranostic agent, PROTAC B4 led to significant reduction of nicotinamide adenine dinucleotide (NAD+) and exerted potent antitumor activities both in vitro and in vivo. Collectively, this proof-of-concept study provides a new strategy for the real-time visualization of the process of protein degradation and the improvement of diagnosis and therapeutic efficacy of PROTACs.

The mechanism of colon tissue damage mediated by HIF-1α/NF-κB/STAT1 in high-altitude environment.

The high-altitude environment damages the intestinal mucosal barrier, leading to a high incidence of intestinal diseases and seriously affects the working ability of people at high altitude. However, how high altitude induces intestinal mucosal barrier injury has not been well defined. The purpose of this study was to investigate the mechanism of colonic tissue injury induced by the influence of the high-altitude environment on the colonic microenvironment. Forty-eight SPF C57BL/6J mice were randomly divided into four groups: the control group and three other that were high-altitude exposure groups (Yushu, Qinghai; elevation: 4,010 m; 12 h, 24 h, 48 h). First, HE staining was used to observe the effect of the high-altitude environment on colon histomorphology of mice. The protein expression levels of claudin-1, occludin, and ZO-1 were analyzed by molecular biological methods. We found that altitude caused inflammatory damage to colon tissue. Intestinal hypoxia was measured with the hypoxic probe pimonidazole (PMDZ). Interestingly, we observed a decrease in the concentration of oxygen in the microenvironment in the colonic lumen. We sought to explore the mechanism of colonic mucosal barrier damage at different times when entering high altitude. The expression levels of hypoxia-inducible factors: HIF-1α, STAT1, and NF-κB and of inflammatory factors: IFN-γ, TNF-α, and IL-6 were significantly increased. This work highlights that the high-altitude environment leads to a reduction in the concentration of oxygen in the microenvironment of the colonic lumen, which disrupts the colonic mucosal barrier and ultimately induces and exacerbates intestinal injury.

Ispinesib as an Effective Warhead for the Design of Autophagosome-Tethering Chimeras: Discovery of Potent Degraders of Nicotinamide Phosphoribosyltransferase (NAMPT).

Autophagosome-tethering compounds (ATTECs) are an emerging new technology in targeted protein degradation. However, effective tools and successful examples for autophagosome-tethering chimeras are still rather limited. Herein, ATTEC ispinesib was identified for the first time to be an effective warhead to design autophagosome-tethering chimeras. As a conceptual validation study, the first generation of autophagic degraders of nicotinamide phosphoribosyltransferase (NAMPT) were developed by connecting the NAMPT inhibitor and LC3-binding ispinesib through a flexible linker. In particular, compound A3 significantly induced the degradation of NAMPT through the autophagy-lysosomal pathway, leading to excellent cellular antitumor potency. Ispinesib may have broad applications in the design of potent autophagosome-tethering chimeras.

Hydrophobic Tagging-Induced Degradation of PDEδ in Colon Cancer Cells.

The development of KRAS-PDEδ protein-protein interaction (PPI) inhibitors is generally hampered by limited antitumor activity. Herein, the first hydrophobic tagging (HyT)-based PDEδ degraders were designed. Compound 17c efficiently bound to PDEδ and induced degradation of PDEδ in SW480 colon cancer cells. As compared with PDEδ inhibitor deltazinone, HyT-based degrader 17c exhibited improved antitumor activity toward KRAS mutant cancer cells. This study highlighted the potential of HyT as a valuable chemical tool for tumorigenic PDEδ knockdown, which could be developed into a promising strategy for antitumor drug discovery.

Strategies for designing proteolysis targeting chimaeras (PROTACs).

Proteolysis targeting chimaeras (PROTACs) is a cutting edge and rapidly growing technique for new drug discovery and development. Currently, the largest challenge in the molecular design and drug development of PROTACs is efficient identification of potent and drug-like degraders. This review aims to comprehensively summarize and analyse state-of-the-art methods and strategies in the design of PROTACs. We provide a detailed illustration of the general principles and tactics for designing potent PROTACs, highlight representative case studies, and discuss the advantages and limitations of these strategies. Particularly, structure-based rational PROTAC design and emerging new types of PROTACs (e.g., homo-PROTACs, multitargeting PROTACs, photo-control PROTACs and PROTAC-based conjugates) will be focused on.

Protective effect of salidroside on lung tissue in rats exposed rapidly to high altitude.

OBJECTIVE: To study the protective effect and mechanism of salidroside on lung tissue of rats exposed rapidly to high altitude. METHODS: Thirty-six Wistar male rats were randomly divided into blank control group, model control group, Rhodiola rosea capsule (137 mg/kg) group, salidroside low-dose (14 mg/kg), medium-dose (28 mg/kg) and high-dose (56 mg/kg) groups, with 6 rats in each group. After 5 continuous days of drug administration in the plain lab, rats were rapidly moved to 4010 m plateau field lab. After exposure to hypoxia condition for 3 days the blood gas indexes were detected; the serum levels of inflammatory factors were measured by enzyme linked immunosorbent assay (ELISA); the oxidative stress index of lung tissue was measured; the pathological changes of lung tissue were observed by microscopy with hematoxylin and eosin (HE) staining; and the expression of occludin in lung tissues was determined by western blotting. RESULTS: Compared with blank control group, arterial oxygen saturation (SaO 2), arterial oxygen partial pressure (PaO 2), blood pH, standard bicarbonate (SBC) and actual bicarbonate levels in model control group were significantly decreased, and hemoglobin level was significantly increased (all P<0.05). In the model control group, the contents of mast cell protease (MCP) 1, interleukin (IL)-6 and IL-1ß were significantly increased, while the contents of interferon-γ were significantly decreased (all P<0.01). The contents of glutathione and total superoxide dismutase in the lung tissues of model control group were significantly decreased, while the content of malondialdehyde was significantly increased (all P<0.01). After Rhodiola rosea and salidroside were given, SaO 2, pH, hemoglobin, SBC and actual bicarbonate were improved compared with the model control group. Compared with the model control group, the Rhodiola rosea group and salidroside groups had different degrees of improvement in the contents of the above inflammatory factors and oxidative stress indexes, and the salidroside groups had better improvement in MCP-1 and IL-6 than the Rhodiola rosea group. HE staining showed that, after the administration of Rhodiola rosea capsules and salidroside at low, medium and high doses, the hypoxic injury was significantly improved, the cell wall gradually became thinner, and the alveolar wall gradually became complete. The expression of occludin in the model control group was lower than that in the blank control group ( P<0.05), while the expression of occludin in the salidroside high-dose group was significantly higher than that in the model control group ( P<0.01). CONCLUSION: Salidroside can improve the abnormality of blood gas index, hypoxia symptoms and acid-base balance disorder, dysregulation of inflammatory factors caused by hypoxia in rats, and improve lung tissue injury and oxidative stress injury, which has a protective effect on lung tissue injury of rats exposed rapidly to the high-altitude plateau, and the effect is better than Rhodiola rosea capsule on the whole.

Protective effects of areca nut polyphenols on hypoxic damage of rat pulmonary microvascular endothelial cells.

OBJECTIVE: To investigate the protective effects of areca nut polyphenols on hypoxic damage of rat pulmonary microvascular endothelial cells (PMVECs). METHODS: Malondialdehyde and superoxide dismutase (SOD) were used to determine the optimal modeling of lung hypoxic injury cells. CCK-8 method was used to detect cell viability for determining the effective dose of areca nut polyphenols. Rat PMVECs were divided into control group, hypoxia model group and areca nut polyphenols group. BCA method was used to detect the protein concentration of each group, and the oxidative stress level in PMVECs was measured. Western blotting was used to detect the expression of inflammatory and apoptosis-related proteins. Immunofluorescence staining was used to detect the expression of occludin and zonula occludens (ZO) 1. Transwell chamber was used to detect transendothelial electrical resistance, and rhodamine fluorescent dye was used to detect PMVECs barrier permeability. RESULTS: The hypobaric hypoxia-induced cell injury model was established by culturing PMVECs for 48 h at 1% oxygen concentration. The 20 µg/mL areca nut polyphenols significantly reversed the survival rate and the oxidative stress of PMVECs in hypoxia model group (all P<0.05). Areca nut polyphenols had significant inhibitory effect on the up-regulation of inflammation-related proteins, including nuclear factor-κB (NF-κB) and nuclear factor-E2-related factor (Nrf) 2 in hypoxia model group (all P<0.05). And areca nut polyphenols could reduce hypoxia-induced PMVECs apoptosis by down-regulating the expressions of apoptosis-related proteins, including cysteine aspartic acid specific protease (caspase) 3, Bcl-2 associated X protein (Bax) in PMVECs (all P<0.05). In addition, areca nut polyphenols effectively improves the transendothelial electrical resistance and barrier permeability of PMVECs through elevating the expression of occludin and ZO-1 (all P<0.05). CONCLUSION: Areca nut polyphenols can inhibit the hypoxic damage of PMVECs by reducing oxidative stress and apoptosis down-regulating the expression of inflammatory proteins and reducing membrane permeability.

Discovery of Novel PDEδ Degraders for the Treatment of KRAS Mutant Colorectal Cancer.

KRAS-PDEδ protein-protein interaction represents an appealing target for cancer therapy. However, fast release of high-affinity inhibitors from PDEδ hampered drug binding affinity and antiproliferative activity. To overcome the limitations, the first proteolysis-targeting chimeric (PROTAC) small molecules targeting PDEδ were designed. By employment of PDEδ inhibitor deltazinone (2) and cereblon ligand pomalidomide (6), a series of potent PROTAC PDEδ degraders were obtained. The most promising compound 17f efficiently induced PDEδ degradation and demonstrated significantly improved antiproliferative potency in KRAS mutant SW480 cells. Compound 17f also achieved significant tumor growth inhibition in the SW480 colorectal cancer xenograft model. This proof-of-concept study provided a new strategy to validate the druggability of KRAS-PDEδ interaction and offered an effective lead compound for the treatment of KRAS mutant cancer.

Scaffold Hopping of Natural Product Evodiamine: Discovery of a Novel Antitumor Scaffold with Excellent Potency against Colon Cancer.

Inspired by the natural product evodiamine, a novel antitumor indolopyrazinoquinazolinone scaffold was designed by scaffold hopping. Structure-activity relationship studies led to the discovery of compound 15j, which shows low nanomolar inhibitory activity against the HCT116 cell line. Further antitumor mechanism studies indicated that compound 15j acted by the dual inhibition of topoisomerase 1 and tubulin and induced apoptosis with G2 cell-cycle arrest. The quaternary ammonium salt of compound 15j (compound 15js) exhibited excellent in vivo antitumor activity (TGI = 66.6%) in the HCT116 xenograft model with low toxicity. Indolopyrazinoquinazolinone derivatives represent promising multitargeting antitumor leads for the development of novel antitumor agents.

Discovery of novel Syk/PDGFR-α/c-Kit inhibitors as multi-targeting drugs to treat rheumatoid arthritis.

Due to the complex biological pathways involved in rheumatoid arthritis, discovery of multi-targeting small molecules provides an effective strategy to achieve better efficacy and lower toxicity. Herein the first Syk/PDGFR-α/c-Kit inhibitors were designed and evaluated. Dihydrofuropyrimidine derivative 13 showed potent inhibitory activity against the three targets. Importantly, compound 13 exhibited good cellular efficacy against fibroblast-like synoviocytes (IC50 = 3.21 µM) and mouse bone marrow-derived mast cells (IC50 = 2.03 µM) and significantly decreased the secretion of inflammatory cytokines. Thus, Syk/PDGFR-α/c-Kit triple inhibitor 13 represented a promising lead compound for the treatment of RA.