Development and therapeutic potential of GSPT1 molecular glue degraders: A medicinal chemistry perspective.

Unprecedented therapeutic targeting of previously undruggable proteins has now been achieved by molecular-glue-mediated proximity-induced degradation. As a small GTPase, G1 to S phase transition 1 (GSPT1) interacts with eRF1, the translation termination factor, to facilitate the process of translation termination. Studied demonstrated that GSPT1 plays a vital role in the acute myeloid leukemia (AML) and MYC-driven lung cancer. Thus, molecular glue (MG) degraders targeting GSPT1 is a novel and promising approach for treating AML and MYC-driven cancers. In this Perspective, we briefly summarize the structural and functional aspects of GSPT1, highlighting the latest advances and challenges in MG degraders, as well as some representative patents. The structure-activity relationships, mechanism of action and pharmacokinetic features of MG degraders are emphasized to provide a comprehensive compendium on the rational design of GSPT1 MG degraders. We hope to provide an updated overview, and design guide for strategies targeting GSPT1 for the treatment of cancer.

Self-supply of hydrogen peroxide by a bimetal-based nanocatalytic platform to enhance chemodynamic therapy for tumor treatment.

The Tumor Microenvironment (TME) is characterized by low pH, hypoxia, and overexpression of glutathione (GSH). Owing to the complexity of tumor pathogenesis and the heterogeneity of the TME, achieving satisfactory efficacy with a single treatment method is difficult, which significantly impedes tumor treatment. In this study, composite nanoparticles of calcium-copper/alginate-hyaluronic acid (CaO2-CuO2@SA/HA NC) with pH and GSH responsiveness were prepared for the first time through a one-step synthesis using hyaluronic acid (HA) as a targeting ligand. Nanoparticles loaded with H2O2 can enhance the ChemoDynamic Therapy (CDT) effects. Simultaneously, Cu2+ can generate oxygen in the TME and alleviate hypoxia in tumor tissue. Cu2+ and H2O2 undergo the Fenton reaction to produce cytotoxic hydroxyl radicals and Ca2+ ions, which enhance the localization and clearance of nanoparticles in tumor cells. Additionally, HA and sodium alginate (SA) were utilized to improve the targeting and biocompatibility of the nanoparticles. FTIR, XRD, DLS, SEM, TEM, and other analytical methods were used to investigate their physical and chemical properties. The results indicate that the CaO2-CuO2@SA/HA NC prepared using a one-step method had a particle size of 220 nm, a narrow particle size distribution, and a uniform morphology. The hydrogen peroxide self-supplied nanodrug delivery system exhibited excellent pH-responsive release performance and glutathione-responsive •OH release ability while also reducing the level of reactive oxide species (ROS) quenching. In vitro cell experiments, no obvious side effects on normal tissues were observed; however, the inhibition rate of malignant tumors HepG2 and DU145 exceeded 50%. The preparation of CaO2-CuO2@SA/HA NC nanoparticles, which can achieve both chemokinetic therapy and ion interference therapy, has demonstrated significant potential for clinical applications in cancer therapy.

Discovery of a highly potent NPAS3 heterodimer inhibitor by covalently modifying ARNT.

Neuronal PAS domain protein 3 (NPAS3), a basic helix-loop-helix PER-ARNT-SIM (bHLH-PAS) family member, is a pivotal transcription factor in neuronal regeneration, development, and related diseases, regulating the expression of downstream genes. Despite several modulators of certain bHLH-PAS family proteins being identified, the NPAS3-targeted compound has yet to be reported. Herein, we discovered a hit compound BI-78D3 that directly blocks the NPAS3-ARNT heterodimer formation by covalently binding to the aryl hydrocarbon receptor nuclear translocator (ARNT) subunit. Further optimization based on the hit scaffold yielded a highly potent Compound 6 with a biochemical EC50 value of 282 ± 61 nM and uncovered the 5-nitrothiazole-2-sulfydryl as a cysteine-targeting covalent warhead. Compound 6 effectively down-regulated NPAS3's transcriptional function by disrupting the interface of NPAS3-ARNT complexes at cellular level. In conclusion, our study identifies the 5-nitrothiazole-2-sulfydryl as a cysteine-modified warhead and provides a strategy that blocks the NPAS3-ARNT heterodimerization by covalently conjugating ARNT Cys336 residue. Compound 6 may serve as a promising chemical probe for exploring NPAS3-related physiological functions.

A critical update on the strategies towards small molecule inhibitors targeting Serine/arginine-rich (SR) proteins and Serine/arginine-rich proteins related kinases in alternative splicing.

>90% of genes in the human body undergo alternative splicing (AS) after transcription, which enriches protein species and regulates protein levels. However, there is growing evidence that various genetic isoforms resulting from dysregulated alternative splicing are prevalent in various types of cancers. Dysregulated alternative splicing leads to cancer generation and maintenance of cancer properties such as proliferation differentiation, apoptosis inhibition, invasion metastasis, and angiogenesis. Serine/arginine-rich proteins and SR protein-associated kinases mediate splice site recognition and splice complex assembly during variable splicing. Based on the impact of dysregulated alternative splicing on disease onset and progression, the search for small molecule inhibitors targeting alternative splicing is imminent. In this review, we discuss the structure and specific biological functions of SR proteins and describe the regulation of SR protein function by SR protein related kinases meticulously, which are closely related to the occurrence and development of various types of cancers. On this basis, we summarize the reported small molecule inhibitors targeting SR proteins and SR protein related kinases from the perspective of medicinal chemistry. We mainly categorize small molecule inhibitors from four aspects, including targeting SR proteins, targeting Serine/arginine-rich protein-specific kinases (SRPKs), targeting Cdc2-like kinases (CLKs) and targeting dual-specificity tyrosine-regulated kinases (DYRKs), in terms of structure, inhibition target, specific mechanism of action, biological activity, and applicable diseases. With this review, we are expected to provide a timely summary of recent advances in alternative splicing regulated by kinases and a preliminary introduction to relevant small molecule inhibitors.

Copper(II)-Catalyzed Tandem Reaction: Synthesis of Furo[3,2-c]coumarin Derivatives and Evaluation for Photophysical Properties.

An efficient protocol for synthesizing furo[3,2-c]coumarin derivatives is described. The novel reaction could afford the desired furocoumarins with good to excellent yields in a mild and rapid manner. Large substrate scope screening and scale-up preparation have also been accomplished, and selected compounds were evaluated for their photophysical properties.

Design, synthesis and biological evaluation of a novel spiro oxazolidinedione as potent p300/CBP HAT inhibitor for the treatment of ovarian cancer.

Histone acetylation is one of the most essential parts of epigenetic modification, mediating a variety of complex biological functions. In these procedure, p300/CBP could catalyze the acetylation of lysine 27 on histone 3 (H3K27ac), and had been reported to mediate tumorigenesis and development in a variety of tumors by enhancing chromatin transcription activity. Ovarian cancer, as an extremely malignant tumor, has also been observed to undergo abnormal acetylation of histones. However, whether the treatment of ovarian cancer could be achieved by inhibiting the acetylation activity of p300/CBP on H3K27 has not been well investigated. In this article, we modified the structure of p300/CBP HAT domain inhibitor A-485 and obtained a highly active small molecule known as 13f, which has an IC50 value of 0.49 nM for inhibiting the in vitro enzyme activity of p300, as well as the anti-proliferation IC50 value on ovarian cancer cell line OVCAR-3 was 153 nM. In addition, 13f had strong acetylase family selectivity, good metabolic stability and promising in vivo anti-tumor activity in OVCAR-3 xenograft model. The discovery of 13f revealed a more active chemical entity of the HATs domain of p300/CBP and provided a novel idea for the application of epigenetic inhibitors in the treatment of ovarian cancer.

Unconventional Passive Enhancement of Transdermal Drug Delivery: toward a Mechanistic Understanding of Penetration Enhancers Releasing from Acrylic Pressure-Sensitive Adhesive of Patches.

PURPOSE: Penetration enhancers (PEs) enhancing efficacy depends on two processes: PEs release from patches and action on skin. Compared with their action on skin, PEs release process was poorly understood. Therefore, the purpose of this study was to make a mechanistic understanding of PEs release from acrylic pressure-sensitive adhesive of patches and propose an unconventional enhancement of PEs efficacy. METHODS: PEs efficacy was evaluated both in drug permeation study and drug pharmacokinetic study. Confocal Raman spectroscopy was employed to observe PEs release behavior by mapping PEs dynamic distribution in skin. The mechanism of PEs release behavior was provided from molecular interaction and rheology using FT-IR, molecular docking, molecular dynamic simulation and rheometer, separately. RESULTS: The release behavior of PEs themselves greatly restricted their efficacy. By using PEG 400, an improvement of oleic acid (OA) release behavior was achieved, and the efficacy of OA was significantly enhanced with enhancing ratio (ER) from 2.69 to 4.10 and AUClast from 1574 ± 87 to 2664 ± 249 ng·h/mL, separately. The improvement of OA release behavior was primarily resulted from reduction of the interaction between OA and adhesive, which was caused by other small molecules with a strong ability in forming hydrogen bonds with adhesive. Also, the rigidity of adhesive was a factor in affecting PEs release behavior. CONCLUSIONS: An unconventional passive enhancement of transdermal drug delivery was achieved via improving PEs themselves releasing from acrylic pressure-sensitive adhesive. Graphical abstract Influence of PEs release behavior on drug permeation through skin and molecular mechanism.

A critical update on the strategies towards modulators targeting androgen receptors.

Prostate cancer is the most common carcinoma of the male urinary system in developed countries. Androgen deprivation therapy has been commonly used in the treatment of prostate cancer for decades, but most patients will inevitably develop into more aggressive castration-resistant prostate cancer. Therefore, novel strategies are urgent to address this resistance mechanism. In this review, we discussed some new strategies for targeting androgen receptors through degradation pathways as potential treatments for prostate cancer.

Discovery of novel USP8 inhibitors via Ubiquitin-Rho-110 fluorometric assay based high throughput screening.

USP8, one member of deubiquitinating enzymes (DUBs) families, maintains the ubiquitination level of EGFR and regulates the downstream signaling pathways. The deregulation of USP8 has been implicated in many human diseases, especially in cancer. Therefore, USP8 has been identified as a promising target for drug design. Herein, via high throughput screening based on Ubiquitin-rhodamine-110 (Ubiquitin-Rho-110) fluorometric activity assay, we discovered a novel inhibitor DC-U43. By structure optimization, DC-U43-10 reached a half-maximal inhibitory concentration (IC50) value of 2.6 ± 1.1 µM and exhibited 10-fold selectivity against USP7. The binding between DC-U43-10 and USP8 was validated by surface plasmon resonance (SPR) assay with a KD value of 10.5 ± 3.7 µM. It also inhibited the colony formation of H1975 cells. Hence, DC-U43-10 represents a kind of USP8 inhibitors with novel scaffold and has broad prospects for being a probe for USP8-related academic and clinical research.

A review on flavones targeting serine/threonine protein kinases for potential anticancer drugs.

Protein kinases have been important targets for antitumor targets due to their key roles in regulating multiple cell signaling pathways. Numerous compounds containing flavonoid scaffold as an indispensable anchor have been found to be potent inhibitors of protein kinases. Some of these flavonoids have been in clinical research as protein kinases inhibitors. Thus, the present review mainly focuses on the structural requirement for anticancer potential of flavone derivatives targeting several key serine/threonine protein kinases. This information may provide an opportunity to scientists of medicinal chemistry to design multi-functional flavone derivatives for the treatment of cancer.

Design, synthesis and evaluation of phthalazinone thiohydantoin-based derivative as potent PARP-1 inhibitors.

Two new series of compounds were designed and synthesized as potent PARP-1 inhibitors. These compounds were evaluated for PARP-1 enzyme and cellular inhibitory activities. All efforts lead to the identification of 9k (named as LG-12) with efficient potency both for PARP-1 and BRCA1 deficient MDA-MB-436 cells. Additionally, the novel PARP-1 inhibitor LG-12 is an efficient chemosensitizer, which could potentiate the anti-cancer effect of TMZ. Our data presented herein provide a comprehensive preclinical in vitro evaluation of the potential therapeutic efficacy and potency of chemotherapeutic agent-PARP-1 inhibitor combinations for LG-12. The combined results indicated that LG-12 could be a promising candidate for further study.

Discovery of cyanopyridine scaffold as novel indoleamine-2,3-dioxygenase 1 (IDO1) inhibitors through virtual screening and preliminary hit optimisation.

With the aim of discovering novel IDO1 inhibitors, a combined similarity search and molecular docking approach was employed to the discovery of 32 hit compounds. Testing the screened hit compounds has led to several novel submicromolar inhibitors. Especially for compounds LVS-019 with cyanopyridine scaffold, showed good IDO1 inhibitory activity. To discover more compounds with similar structures to LVS-019, a shape-based model was then generated on the basis of it and the second-round virtual screening was carried out leading to 23 derivatives. Molecular docking studies suggested a possible binding mode of LVS-019, which provides a good starting point for the development of cyanopyridine scaffold compounds as potent IDO1 inhibitor. To improve potency of these hits, we further designed and synthesised another 14 derivatives of LVS-019. Among these compounds, LBJ-10 showed improved potency compared to the hits and displayed comparable potency to the control GDC-0919 analogue. LBJ-10 can serve as ideal leads for further modifications as IDO1 inhibitors for cancer treatment.

Palladium(II)-Catalyzed Reaction of Lawsones and Propargyl Carbonates: Construction of 2,3-Furanonaphthoquinones and Evaluation as Potential Indoleamine 2,3-Dioxygenase Inhibitors.

An efficient reaction utilizing propargyl carbonates through Claisen rearrangement to synthesize furanonaphthoquinones is described. The remarkable transformation exhibits excellent functional group tolerance, affording the target furanonaphthoquinones in moderate to good yields (41-85%) under mild reaction conditions. Scaled-up preparation of the model product can make this reaction a method of choice for synthesis of furanonaphthoquinone derivatives. The resulting furanonaphthoquinones were evaluated as potential indoleamine 2,3-dioxygenase inhibitors in vitro.

Current knowledge on the nucleotide agonists for the P2Y2 receptor.

P2Y receptors are G-protein-coupled receptors (GPCRs) for extracellular nucleotides. There are eight mammalian P2Y receptor subtypes (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14). P2Y2 receptors are widely expressed and play important roles in multiple functionalities. Diquafosol tetrasodium, known as INS365, which was the first P2Y2 receptor agonists that had been approved in April 2010 and launched in Japan by Santen Pharmaceuticals. Besides, a series of similar agonists for the P2Y2 receptor are undergoing development to cure different diseases related to the P2Y2 receptor. This article illustrated the structure and functions of the P2Y2 receptor and focused on several kinds of agonists about their molecular structures, research progress and chemical synthesis methods. Last but not the least, we summarized the structures-activity relationship (SAR) of agonists for the P2Y2 receptor and expected more efficient agonists for the P2Y2 receptor.

Discovery of Wogonin-based PROTACs against CDK9 and capable of achieving antitumor activity.

Wogonin is a natural product isolated from the Scutellaria baicalensis and has been proved to be a potent and selective inhibitor of CDK9. Using this scaffold, we designed and synthesized a series of proteolysis targeting chimeras (PROTACs) targeting CDK9 by recruiting ubiquitin E3 ligase cereblon (CRBN). For constructing diverse Wogonin-based PROTACs, a "click chemistry" approach was employed for the synthesis of CDK9-targeting PROTACs. The results of western blotting assays showed that compounds containing triazole group in the linker could selectively downregulate the intracellular CDK9 level. Among these compounds, 11c could selectively degrade CDK9 in a concentration-dependent manner. In addition, the application of the proteasome inhibitor MG132 and CRBN siRNA silencing confirmed that 11c could promote the proteasome-dependent and CRBN-dependent degradation. Consistent with the degradation of the CDK9 protein, 11c selectively inhibits proliferation of CDK9-overexpressed cancer cells. Thus, our Wogonin-based PROTAC would be an efficient probe that induces the degradation of CDK9.

Synthesis, evaluation and quantitative structure-activity relationship (QSAR) analysis of Wogonin derivatives as cytotoxic agents.

A novel series of 49 wogonin derivatives were synthesized by introducing group at 7-, 8- or B ring of wogonin. The cytotoxic activities against HepG2, A549 and BCG-823 cancer cell lines were also investigated in vitro. Several of them showed obvious cytotoxic activities and compound 3h possessed the highest potency against HepG2, A549, and BCG-823 with IC50 values of 1.07µM, 1.74µM and 0.98µM, respectively. A quantitative structure-activity relationship (QSAR) study of these synthetic derivatives as well as wogonin indicated that high solubility and low octanol/water partition coefficient are favorable, and excessive electrostatic properties and refractivity are unfavorable for the cytotoxic activities of these wogonin derivatives. These findings and results provide a base for further investigations.

Novel naphtho[2,1-d]oxazole-4,5-diones as NQO1 substrates with improved aqueous solubility: Design, synthesis, and in vivo antitumor evaluation.

A new series of ortho-naphthoquinone analogs of ß-lapachone were designed, synthesized and evaluated. The biological results indicated that most of our compounds were efficient substrates for NQO1. The new scaffold with water-soluble side chain resulted in greater solubility under acidic condition compared to ß-lapachone. Thus avoiding the use of hydroxylpropyl ß-cyclodextrin which would finally cause the rapid drug clearance from the blood and dose-limiting toxicity in the form of hemolytic anemia. The most soluble and promising compound in this series was 2-((4-benzylpiperazin-1-yl)methyl)naphtho[2,1-d]oxazole-4,5-dione (3k), which inhibited cancer cell (NQO1-rich A549 cell line) growth at IC50 values of 4.6±1.0µmol·L(-1). Furthermore, compound 3k had in vivo antitumor activity in an A549 tumor xenografts mouse model comparable to the activity obtained with ß-lapachone. The results indicated that these ortho-naphthoquinones could serve as promising leads for further optimization as novel substrates for NQO1.

Novel natural-product-like caged xanthones with improved druglike properties and in vivo antitumor potency.

DDO-6101, a natural-product-like caged xanthone discovered previously in our laboratory based on the pharmacophoric scaffold of Garcinia natural product gambogic acid (GA), shows potent cytotoxicity in vitro but poor efficacy in vivo due to its poor druglike properties. In order to improve the druglike properties and in vivo cytotoxic potency, a novel series of 19 prenyl group-modified derivatives of DDO-6101 was synthesized and evaluated for their in vitro antitumor activity and druglike properties. The SAR and SPR information of these compounds was also obtained. In the light of the in vitro antitumor activity and druglike properties such as aqueous solubility and permeability, compound 6f (named as DDO-6306) was advanced into in vivo efficacy experiment. The results showed that DDO-6306 is more potent than DDO-6101 in vivo and is a promising antitumor candidate for further evaluation.

Synthesis and evaluation of (±)-dunnione and its ortho-quinone analogues as substrates for NAD(P)H:quinone oxidoreductase 1 (NQO1).

Natural product (±)-dunnione (2) and its ortho-quinone analogues (3-8) were synthesized and found to be substrates for NQO1. The structure-activity relationship study revealed that the biological activity was favored by the presence of methyl group at the C ring and methoxy group at the A ring. The docking studies supported the rationalization of the metabolic studies. Deeper location in the active site of NQO1, interactions with hydrophobic pocket and C-H…π interactions with the adjacent Phe178 residue contributed to the better catalytic efficiency and specificity to NQO1. Cytotoxicity studies and determination of superoxide (O2(-)) production in the presence and absence of the NOQ1 inhibitor dicoumarol confirmed that the ortho-quinones exerted their antitumor activity through NQO1-mediated ROS production by redox cycling.