Computationally guided discovery of novel non-steroidal AR-GR dual antagonists demonstrating potency against antiandrogen resistance.

As a major class of medicine for treating the lethal type of castration-resistant prostate cancer (PCa), long-term use of androgen receptor (AR) antagonists commonly leads to antiandrogen resistance. When AR signaling pathway is blocked by AR-targeted therapy, glucocorticoid receptor (GR) could compensate for AR function especially at the late stage of PCa. AR-GR dual antagonist is expected to be a good solution for this situation. Nevertheless, no effective non-steroidal AR-GR dual antagonist has been reported so far. In this study, an AR-GR dual binder H18 was first discovered by combining structure-based virtual screening and biological evaluation. Then with the aid of computationally guided design, the AR-GR dual antagonist HD57 was finally identified with antagonistic activity towards both AR (IC50 = 0.394 µM) and GR (IC50 = 17.81 µM). Moreover, HD57 could effectively antagonize various clinically relevant AR mutants. Further molecular dynamics simulation provided more atomic insights into the mode of action of HD57. Our research presents an efficient and rational strategy for discovering novel AR-GR dual antagonists, and the new scaffold provides important clues for the development of novel therapeutics for castration-resistant PCa.

Overexpression of PxαE14 Contributing to Detoxification of Multiple Insecticides in Plutella xylostella (L.).

The diamondback moth, Plutella xylostella (L.), has evolved with varying degrees of resistance to almost all major classes of insecticides and has become the most resistant pest worldwide. The multiresistance to different types of insecticides has been frequently reported in P. xylostella, but little is known about the mechanism. In this study, a carboxylesterase (CarE) gene, PxαE14, was found significantly overexpressed in a field-evolved multiresistant P. xylostella population and can be dramatically induced by eight of nine tested insecticides. Results of the real-time quantitative polymerase chain reaction (RT-qPCR) showed that PxαE14 was predominantly expressed in the midgut and malpighian tubule of larvae. Knockdown of PxαE14 dramatically increased the susceptibility of the larvae to ß-cypermethrin, bifenthrin, chlorpyrifos, fenvalerate, malathion, and phoxim, while overexpression of PxαE14 in Drosophila melanogaster increased the tolerance of the fruit flies to these insecticides obviously. More importantly, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay showed that the recombinant PxαE14 expressed in Escherichia coli exhibited metabolic activity against the six insecticides. The homology modeling, molecular docking, and molecular dynamics simulation analyses showed that these six insecticides could stably bind to PxαE14. Taken together, these results demonstrate that constitutive and inductive overexpression of PxαE14 contributes to detoxification of multiple insecticides involved in multiresistance in P. xylostella. Our findings provide evidence for understanding the molecular mechanisms underlying the multiresistance in insect pests.

Discovery of a novel nonsteroidal selective glucocorticoid receptor modulator by virtual screening and bioassays.

Synthetic glucocorticoids (GCs) have been widely used in the treatment of a broad range of inflammatory diseases, but their clinic use is limited by undesired side effects such as metabolic disorders, osteoporosis, skin and muscle atrophies, mood disorders and hypothalamic-pituitary-adrenal (HPA) axis suppression. Selective glucocorticoid receptor modulators (SGRMs) are expected to have promising anti-inflammatory efficacy but with fewer side effects caused by GCs. Here, we reported HT-15, a prospective SGRM discovered by structure-based virtual screening (VS) and bioassays. HT-15 can selectively act on the NF-κB/AP1-mediated transrepression function of glucocorticoid receptor (GR) and repress the expression of pro-inflammation cytokines (i.e., IL-1ß, IL-6, COX-2, and CCL-2) as effectively as dexamethasone (Dex). Compared with Dex, HT-15 shows less transactivation potency that is associated with the main adverse effects of synthetic GCs, and no cross activities with other nuclear receptors. Furthermore, HT-15 exhibits very weak inhibition on the ratio of OPG/RANKL. Therefore, it may reduce the side effects induced by normal GCs. The bioactive compound HT-15 can serve as a starting point for the development of novel therapeutics for high dose or long-term anti-inflammatory treatment.

Discovery of novel antagonists targeting the DNA binding domain of androgen receptor by integrated docking-based virtual screening and bioassays.

Androgen receptor (AR), a ligand-activated transcription factor, is a master regulator in the development and progress of prostate cancer (PCa). A major challenge for the clinically used AR antagonists is the rapid emergence of resistance induced by the mutations at AR ligand binding domain (LBD), and therefore the discovery of novel anti-AR therapeutics that can combat mutation-induced resistance is quite demanding. Therein, blocking the interaction between AR and DNA represents an innovative strategy. However, the hits confirmed targeting on it so far are all structurally based on a sole chemical scaffold. In this study, an integrated docking-based virtual screening (VS) strategy based on the crystal structure of the DNA binding domain (DBD) of AR was conducted to search for novel AR antagonists with new scaffolds and 2-(2-butyl-1,3-dioxoisoindoline-5-carboxamido)-4,5-dimethoxybenzoicacid (Cpd39) was identified as a potential hit, which was competent to block the binding of AR DBD to DNA and showed decent potency against AR transcriptional activity. Furthermore, Cpd39 was safe and capable of effectively inhibiting the proliferation of PCa cell lines (i.e., LNCaP, PC3, DU145, and 22RV1) and reducing the expression of the genes regulated by not only the full-length AR but also the splice variant AR-V7. The novel AR DBD-ARE blocker Cpd39 could serve as a starting point for the development of new therapeutics for castration-resistant PCa.

Discovery of novel DprE1 inhibitors via computational bioactivity fingerprints and structure-based virtual screening.

Decaprenylphosphoryl-ß-D-ribose oxidase (DprE1) plays important roles in the biosynthesis of mycobacterium cell wall. DprE1 inhibitors have shown great potentials in the development of new regimens for tuberculosis (TB) treatment. In this study, an integrated molecular modeling strategy, which combined computational bioactivity fingerprints and structure-based virtual screening, was employed to identify potential DprE1 inhibitors. Two lead compounds (B2 and H3) that could inhibit DprE1 and thus kill Mycobacterium smegmatis in vitro were identified. Moreover, compound H3 showed potent inhibitory activity against Mycobacterium tuberculosis in vitro (MICMtb = 1.25 µM) and low cytotoxicity against mouse embryo fibroblast NIH-3T3 cells. Our research provided an effective strategy to discover novel anti-TB lead compounds.

Phenyl imidazolidin-2-ones antagonize a ß-adrenergic-like octopamine receptor in diamondback moth (Plutella xylostella).

BACKGROUND: The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests on cruciferous vegetables. However, resistance has emerged to current chemical and biological insecticides used for P. xylostella control, indicating the necessity of screening new targets on P. xylostella, and finding new insecticides against P. xylostella. In particular, octopamine receptors are representative G protein-coupled receptors found only in invertebrates and are potential targets for identifying novel insecticides. RESULTS: A ß-adrenergic-like octopamine receptor gene (PxOA2B1) was cloned, and its pharmacological characteristics in P. xylostella were studied. The results demonstrated that octopamine could activate the PxOA2B1 receptor, with a half-maximal effective concentration (EC50 ) of 49.5 nm. Amitraz, an insecticide and acaricide, and its metabolite (N-2,4-dimethylphenyl-N'-methylformamidine; DPMF) were also found to act as PxOAB1R agonists. We synthesized phenyl imidazolidin-2-one derivatives 3a-h using DPMF as the lead compound, and compounds 3a-h showed similar antagonist activities as phentolamine, mianserin and chlorpromazine. In particular, 3d, with an EC50 of 25.2 nm, showed very similar antagonist activity to mianserin. CONCLUSION: This research found that PxOAB1R might be a potential target for P. xylostella control. Phenyl imidazolidin-2-ones could be novel potential antagonists targeted at octopamine receptors and would be useful tools for the design and development of novel insecticides. © 2021 Society of Chemical Industry.

Secretory expression of a bispecific antibody targeting tumor necrosis factor and ED-B fibronectin in Pichia pastoris and its functional analysis.

Specific targeting of tumor necrosis factor (TNF)-α antagonist to the inflamed site could increase its efficacy and reduce side-effects. Here, we constructed a bispecific diabody (BsDb) that targets TNF-α and ED-B-containing fibronectin, a fibronectin isoform specifically expressed in the pannus of the inflamed synovium in rheumatoid arthritis. BsDb was secreted from Pichia pastoris as functional protein and was purified to homogeneity. BsDb could simultaneously bind to human TNF-α and B-FN and neutralize TNF-α action. Additionally, BsDb showed a significant gain both in the antigen-binding affinity and in TNF-α-neutralizing ability as compared to its original antibodies, L19 and anti-TNF-α scFv, which were produced in E. coli. BsDb was constructed and was endowed with enhanced bioactivities and improved production processing. Therefore, it holds great potential for in vivo applications.

[Construction and functional analysis of a bispecific antibody that targets TNF-α and ED-B].

In order to enhance the specificity of TNF-α monoclonal antibody to inflamed site, a bispecific antibody BsDb that targets TNF-α and the extra-domain B (ED-B) of fibronectin (FN) was constructed by covalently linking the anti-TNF-α single chain Fv antibody (TNF-scFv) and the anti-ED-B scFv L19 via a flexible peptide linker deriving from human serum albumin (HSA). ED-B is an antigen specifically expressed at the inflamed site. BsDb is expressed in E. coli, identified by immunoblot, and purified with affinity chromatography. This was followed by further examination of its bioactivities and pharmacokinetics. We demonstrated that BsDb retained the immunoreactivity of its original antibodies as it could simultaneously bind to TNF-α and ED-B and neutralize the biological action of TNF-α. In the collagen-induced arthritis mice model, BsDb selectively accumulate in the inflamed joint with a maximal uptake of (12.2 ± 1.50)% ID/g in a single inflamed paw and retain in the inflamed paw for at least 72 h. In contrast, BsDb showed a short serum half-life of (0.50 ± 0.05) h and a rapid clearance from normal tissues. The findings reported herein indicate that BsDb has good specificity to the inflamed site and low toxicity to normal tissues. BsDb is therefore likely to have greater clinical applications in the treatment of rheumatoid arthritis and other autoimmune diseases. This laid a stable basis for its preclinical study.

[Construction of IL-1Ra-HSA fusion protein and analysis of its bioactivity and pharmacokinetics].

In order to increase the plasma half-life and tissue specificity of IL-1 receptor antagonist, a recombinant fusion protein IL-1Ra-HSA, linked by a rigid peptide linker PAPAP, was engineered and expressed by the Pichia pastoris host cells. The fusion protein was secreted to the host cells culture, identified by Western blot, and purified by affinity chromatography. This was followed by a further examination of its bioactivity and pharmacokinetics. Our results demonstrated that the fusion protein retained the antagonist activity of IL-1Ra, capable of binding specifically to the IL-1 receptor on human melanoma A375.S2 cells, and inhibits the cytolytic effect of IL-1beta to A375.S2 cells. Albumin fusion dramatically extended the half-life of IL-1Ra and resulted in a specific accumulation of IL-1Ra in the arthritic paws and a lower distribution of IL-1Ra in other organs such as liver, kidney, spleen and lung in mice with collagen-induced arthritis. The findings reported herein indicate that the fusion protein is likely to have greater clinical applications in areas such as the treatment of rheumatoid arthritis.