Aspirin, one of the oldest and most common anti-inflammatory agents, has recently been shown to reduce cancer risks. The principal pharmacological effects of aspirin are known to arise from its covalent modification of cyclooxygenase-2 (COX-2) through acetylation of Ser530, but the detailed mechanism of its biochemical action and specificity remains to be elucidated. In this work, we have filled this gap by employing a state-of-the-art computational approach, Born–Oppenheimer molecular dynamics simulations with ab initio quantum mechanical/molecular mechanical potential and umbrella sampling. Our studies have characterized a substrate-assisted inhibition mechanism for aspirin acetylating COX: it proceeds in two successive stages with a metastable tetrahedral intermediate, in which the carboxyl group of aspirin serves as the general base. The computational results confirmed that aspirin would be 10–100 times more potent against COX-1 than against COX-2, and revealed that this inhibition specificity between the two COX isoforms can be attributed mainly to the difference in kinetics rate of the covalent inhibition reaction, not the aspirin-binding step. The structural origin of this differential inhibition of the COX enzymes by aspirin has also been elucidated.

Gold(I) N‐heterocyclic carbene (AuI‐NHC) complexes have emerged as potential anticancer agents owing to their high cytotoxicity and stability. Integration of their above unique functions with customized aggregation‐induced emission (AIE) luminogens to achieve specific bioimaging and efficient theranostics to cancer is highly desirable but is rarely studied. Now, a series of novel AuI‐NHC compounds were developed with AIE characteristics. A complex with a PPh3 ligand was selected out as it could achieve both prominent specific imaging of various cancer cells and efficient inhibition of their growth with negligible toxic effects on normal cells due to the targeting binding and strong inhibition towards thioredoxin reductase. This complex could also act as a powerful radiosensitizer to boost the anticancer efficacy with performance superior to that of popularly used auranofin. It holds great potential as a specific and effective theranostic drug in cancer diagnosis and precise therapy.

Fragment-based drug discovery is a widely used strategy for drug design in both academic and pharmaceutical industries. Although fragments can be linked to generate candidate compounds by the latest deep generative models, generating linkers with specified attributes remains underdeveloped. In this study, we presented a novel framework, DRlinker, to control fragment linking toward compounds with given attributes through reinforcement learning. The method has been shown to be effective for many tasks from controlling the linker length and log P, optimizing predicted bioactivity of compounds, to various multiobjective tasks. Specifically, our model successfully generated 91.0% and 93.9% of compounds complying with the desired linker length and log P and improved the 7.5 pChEMBL value in bioactivity optimization. Finally, a quasi-scaffold-hopping study revealed that DRlinker could generate nearly 30% molecules with high 3D similarity but low 2D similarity to the lead inhibitor, demonstrating the benefits and applicability of DRlinker in actual fragment-based drug design.

Prostate cancer (PCa) patients who progress to metastatic castration-resistant PCa (mCRPC) mostly have poor outcomes due to the lack of effective therapies. Our recent study established the orphan nuclear receptor ROR γ as a novel therapeutic target for CRPC. Here, we reveal that elaiophylin (Elai), an antibiotic from Actinomycete streptomyces , is a novel ROR γ antagonist and showed potent antitumor activity against CRPC in vitro and in vivo . We demonstrated that Elai selectively binded to ROR γ protein and potently blocked ROR γ transcriptional regulation activities. Structure–activity relationship studies showed that Elai occupied the binding pocket with several key interactions. Furthermore, Elai markedly reduced the recruitment of ROR γ to its genomic DNA response element (RORE), suppressed the expression of ROR γ target genes AR and AR variants, and significantly inhibited PCa cell growth. Importantly, Elai strongly suppressed tumor growth in both cell line based and patient-derived PCa xenograft models. Taken together, these results suggest that Elai is novel therapeutic ROR γ inhibitor that can be used as a drug candidate for the treatment of human CRPC.

β-Lactamases confer resistance to β-lactam-based antibiotics. There is great interest in understanding their mechanisms to enable the development of β-lactamase-specific inhibitors. The mechanism of class A β-lactamases has been studied extensively, revealing Lys-73 and Glu-166 as general bases that assist the catalytic residue Ser-70. However, the specific roles of these two residues within the catalytic cycle remain not fully understood. To help resolve this, we first identified an E166H mutant that is functional but is kinetically slow. We then carried out time-resolved crystallographic study of a full cycle of the catalytic reaction. We obtained structures that represent apo, S*-acylation, andS*-deacylation states and analyzed the conformational changes of His-166. The "in" conformation in the apo structure allows His-166 to form a hydrogen bond with Lys-73. The unexpected "flipped-out" conformation of His-166 in the S*-acylation structure was further examined by molecular dynamics simulations, which suggested deprotonated Lys-73 serving as the general base for acylation. The "revert-in" conformation in theS*-deacylation structure aligns His-166 toward the water molecule that hydrolyzes the acyl adduct. Finally, when the acyl adduct is fully hydrolyzed, His-166 rotates back to the "in" conformation of the apo-state, restoring the Lys-73/His-166 interaction. Using His-166 as surrogate, our study identifies distinct conformational changes within the active site during catalysis. We suggest that the native Glu-166 executes similar changes in a less constricted way. Taken together, this structural series improves our understanding of β-lactam hydrolysis in this important class of enzymes.

Human dihydroorotate dehydrogenase (hDHODH) is an attractive tumor target essential to de novo pyrimidine biosynthesis. Novel potent hDHODH inhibitors with low toxicity are urgently needed. Herein, we demonstrate the isolation of 25 ascochlorin (ASC) derivatives, including 13 new ones, from the coral-derived fungus Acremonium sclerotigenum, and several of them showed pronounced inhibitions against hDHODH and triple-negative breast cancer (TNBC) cell lines, MDA-MB-231/-468. Interestingly, we found that hDHODH is required for proliferation and survival of TNBC cells, and several ASCs significantly inhibited TNBC cell growth and induced their apoptosis via hDHODH inhibition. Furthermore, the novel and potent hDHODH inhibitors (1 and 21) efficiently suppressed tumor growth in patient-derived TNBC xenograft models without obvious body weight loss or overt toxicity in mice. Collectively, our findings offered a novel lead scaffold as the hDHODH inhibitor for further development of potent anticancer agents and a potential therapeutic strategy for TNBC.

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The blockade of A 2A adenosine receptor (A 2A AR) activates immunostimulatory response through regulating signaling in tumor microenvironment. Thus, A 2A AR has been proposed as a promising target for cancer immunotherapy. In this work, we designed a new series of benzo [4,5]imidazo[1,2-a]pyrazin-1-amine derivatives bearing an amide substitution at 3-position to obtain potent antitumor antagonist in vivo. The structure−activity relationship studies were performed by molecular modeling and radioactive assay. The in vitro anticancer activities were evaluated by 3′,5′-cyclic adenosine monophosphate (cAMP) functional and T cell activation assay. The most potent compound 12o•2HCl showed much higher affinity toward A 2A AR (K i = 0.08 nM) and exhibited more significant in vitro immunostimulatory anticancer activity than clinical antagonist AZD4635. More importantly, 12o•2HCl significantly inhibited the growth of triple-negative breast cancer by reversing immunosuppressive tumor microenvironment in the xenograft mouse model without severe toxicity at the testing dose. These results make 12o•2HCl a promising immunotherapy anticancer drug candidate.