Objective To design and synthesize PROTAC degraders targeting the SARS-CoV-2 main protease （M^pro）based on PROTAC technology. Methods Compound 3w was used as the M^pro ligand, and the indole N atom in the solvent-exposed region was selected as the linker attachment site. A series of M^pro PROTACs were designed and synthesized by conjugating compound 3w with the CRBN ligand pomalidomide through alkane linkers of different lengths. The structures of the target compounds were confirmed by ¹H NMR, ¹³C NMR, and HRMS. Western Blot analysis was employed to evaluate their degradation activity and explore its mechanism in M^pro-HEK-293T cells. Results Four novel M^pro PROTACs（A1-A4）were successfully synthesized. The most potent compound A4 demonstrated M^pro degradation activity with a DC₅₀ value of 5.2 μmol/L, and its degradation mechanism was validated. Conclusion A novel class of M^pro PROTAC degraders were successfully designed and synthesized, and their protein degradation capability and mechanism of action were demonstrated. These results provided lead compounds for the research and development of antiviral degraders against SARS-CoV-2.

Membrane protein degradation is a cutting-edge field in targeted protein degradation (TPD). Herein, we developed glypican-3 (GPC3)-mediated lysosome-targeting chimeras (GLTACs) as a novel strategy for the targeted degradation of tumor-specific membrane proteins. GLTACs utilize tumor-specific expression and endocytosis properties of GPC3 to degrade membrane proteins. By conjugating a GPC3-targeting peptide with the ligand of protein of interest (POI), GLTACs induce the formation of a ternary complex that is internalized into lysosomes, leading to the degradation of the POI. The effectiveness and specificity of GLTACs were validated by designing PD-L1, c-Met, and FGFR1 degraders. In particular, GLTAC WP0 potently degraded PD-L1 and induced T-cell-mediated tumor killing against HepG2 cells, highlighting the potential therapeutic applications. The development of GLTAC technology expands the scope of TPD strategies and opens new avenues for discovering novel therapeutic modalities against challenging protein targets.

The role of glial scar after intracerebral hemorrhage(ICH)remains unclear.This study aimed to inves-tigate whether microglia-astrocyte interaction affects glial scar formation and explore the specific function of glial scar.We used a pharmacologic approach to induce microglial depletion during different ICH stages and examine how ablating microglia affects astrocytic scar formation.Spatial transcriptomics(ST)analysis was performed to explore the potential ligand-receptor pair in the modulation of microglia-astrocyte interaction and to verify the functional changes of astrocytic scars at different periods.During the early stage,sustained microglial depletion induced disorganized astrocytic scar,enhanced neutrophil infiltration,and impaired tissue repair.ST analysis indicated that microglia-derived insulin like growth factor 1(IGF1)modulated astrocytic scar formation via mechanistic target of rapamycin(mTOR)signaling activation.Moreover,repopulating microglia(RM)more strongly activated mTOR signaling,facilitating a more protective scar formation.The combination of IGF1 and osteopontin(OPN)was necessary and sufficient for RM function,rather than IGF1 or OPN alone.At the chronic stage of ICH,the overall net effect of astrocytic scar changed from protective to destructive and delayed microglial depletion could partly reverse this.The vital insight gleaned from our data is that sustained microglial depletion may not be a reasonable treatment strategy for early-stage ICH.Inversely,early-stage IGF1/OPN treatment combined with late-stage PLX3397 treatment is a promising therapeutic strategy.This prompts us to consider the complex temporal dynamics and overall net effect of microglia and astrocytes,and develop elaborate treatment strategies at precise time points after ICH.

KRAS‒PDEδ interaction is revealed as a promising target for suppressing the function of mutant KRAS. The bottleneck in clinical development of PDEδ inhibitors is the poor antitumor activity of known chemotypes. Here, we identified novel spiro-cyclic PDEδ inhibitors with potent antitumor activity both in vitro and in vivo. In particular, compound 36l (K _D = 127 ± 16 nmol/L) effectively bound to PDEδ and interfered with KRAS-PDEδ interaction. It influenced the distribution of KRAS in Mia PaCa-2 cells, downregulated the phosphorylation of t-ERK and t-AKT and promoted apoptosis of the cells. The novel inhibitor 36l exhibited significant in vivo antitumor potency in pancreatic cancer patient-derived xenograft (PDX) models. It represents a promising lead compound for investigating the druggability of KRAS‒PDEδ interaction.

Metabolic-associated fatty liver disease (MAFLD), which is previously known as non-alcoholic fatty liver disease (NAFLD), represents a major health concern worldwide with limited therapy. Here, we provide evidence that ferroptosis, a novel form of regulated cell death characterized by iron-driven lipid peroxidation, was comprehensively activated in liver tissues from MAFLD patients. The canonical-GPX4 (cGPX4), which is the most important negative controller of ferroptosis, is downregulated at protein but not mRNA level. Interestingly, a non-canonical GPX4 transcript-variant is induced (inducible-GPX4, iGPX4) in MAFLD condition. The high fat-fructose/sucrose diet (HFFD) and methionine/choline-deficient diet (MCD)-induced MAFLD pathologies, including hepatocellular ballooning, steatohepatitis and fibrosis, were attenuated and aggravated, respectively, in cGPX4-and iGPX4-knockin mice. cGPX4 and iGPX4 isoforms also displayed opposing effects on oxidative stress and ferroptosis in hepatocytes. Knockdown of iGPX4 by siRNA alleviated lipid stress, ferroptosis and cell injury. Mechanistically, the triggered iGPX4 interacts with cGPX4 to facilitate the transformation of cGPX4 from enzymatic-active monomer to enzymatic-inactive oligomers upon lipid stress, and thus promotes ferroptosis. Co-immunoprecipitation and nano LC-MS/MS analyses confirmed the interaction between iGPX4 and cGPX4. Our results reveal a detrimental role of non-canonical GPX4 isoform in ferroptosis, and indicate selectively targeting iGPX4 may be a promising therapeutic strategy for MAFLD.

Nicotinamide phosphoribosyl transferase (NAMPT) is considered as a promising target for cancer therapy given its critical engagement in cancer metabolism and inflammation. However, therapeutic benefit of NAMPT enzymatic inhibitors appears very limited, likely due to the failure to intervene non-enzymatic functions of NAMPT. Herein, we show that NAMPT dampens antitumor immunity by promoting the expansion of tumor infiltrating myeloid derived suppressive cells (MDSCs) via a mechanism independent of its enzymatic activity. Using proteolysis-targeting chimera (PROTAC) technology, PROTAC A7 is identified as a potent and selective degrader of NAMPT, which degrades intracellular NAMPT (iNAMPT) via the ubiquitin-proteasome system, and in turn decreases the secretion of extracellular NAMPT (eNAMPT), the major player of the non-enzymatic activity of NAMPT. In vivo, PROTAC A7 efficiently degrades NAMPT, inhibits tumor infiltrating MDSCs, and boosts antitumor efficacy. Of note, the anticancer activity of PROTAC A7 is superior to NAMPT enzymatic inhibitors that fail to achieve the same impact on MDSCs. Together, our findings uncover the new role of enzymatically-independent function of NAMPT in remodeling the immunosuppressive tumor microenvironment, and reports the first NAMPT PROTAC A7 that is able to block the pro-tumor function of both iNAMPT and eNAMPT, pointing out a new direction for the development of NAMPT-targeted therapies.

The dose-related adverse effects of MDM2‒P53 inhibitors have caused significant concern in the development of clinical safe anticancer agents. Herein we report an unprecedented homo-PROTAC strategy for more effective disruption of MDM2‒P53 interaction. The design concept is inspired by the capacity of sub-stoichiometric catalytic PROTACs enabling to degrade an unwanted protein and the dual functions of MDM2 as an E3 ubiquitin ligase and a binding protein with tumor suppressor P53. The new homo-PROTACs are designed to induce self-degradation of MDM2. The results of the investigation have shown that PROTAC

A great challenge in multi-targeting drug discovery is to identify drug-like lead compounds with therapeutic advantages over single target inhibitors and drug combinations. Inspired by our previous efforts in designing antitumor evodiamine derivatives, herein selective histone deacetylase 1 (HDAC1) and topoisomerase 2 (TOP2) dual inhibitors were successfully identified, which showed potent and antitumor potency. Particularly, compound was orally active and possessed excellent antitumor activity in the HCT116 xenograft model (TGI = 75.2%, 150 mg/kg, .) without significant toxicity, which was more potent than HDAC inhibitor vorinostat, TOP inhibitor evodiamine and their combination. Taken together, this study highlights the therapeutic advantages of evodiamine-based HDAC1/TOP2 dual inhibitors and provides valuable leads for the development of novel multi-targeting antitumor agents.

The trend toward designing large hydrophobic molecules for lead optimization is often associated with poor drug-likeness and high attrition rates in drug discovery and development. Structural simplification is a powerful strategy for improving the efficiency and success rate of drug design by avoiding "molecular obesity". The structural simplification of large or complex lead compounds by truncating unnecessary groups can not only improve their synthetic accessibility but also improve their pharmacokinetic profiles, reduce side effects and so on. This review will summarize the application of structural simplification in lead optimization. Numerous case studies, particularly those involving successful examples leading to marketed drugs or drug-like candidates, will be introduced and analyzed to illustrate the design strategies and guidelines for structural simplification.

Natural product evodiamine and its derivatives represent a promising class of multi-target antitumor agents. However, the clinical development of these compounds has been hampered by a poor understanding of their antitumor mechanisms. To tackle this obstacle, herein, novel fluorescent probes were designed to elucidate the antitumor mode of action of 10-hydroxyevodiamine. This compound was proven to be distributed in the mitochondria and lysosomes and to act by autophagy and apoptosis mechanisms.