Chemoproteomic strategy identifies PfUCHL3 as the target of halofuginone.

The human malaria parasite Plasmodium falciparum (P. falciparum) continues to pose a significant public health challenge, leading to millions of fatalities globally. Halofuginone (HF) has shown a significant anti-P. falciparum effect, suggesting its potential as a therapeutic agent for malaria treatment. In this study, we synthesized a photoaffinity labeling probe of HF to identify its direct target in P. falciparum. Our results reveal that ubiquitin carboxyl-terminal hydrolase 3 (PfUCHL3) acts as a crucial target protein of HF, which modulates parasite growth in the intraerythrocytic cycle. In particular, we discovered that HF potentially forms hydrogen bonds with the Leu10, Glu11, and Arg217 sites of PfUCHL3, thereby inducing an allosteric effect by promoting the embedding of the helix 6' region on the protein surface. Furthermore, HF disrupts the expression of multiple functional proteins mediated by PfUCHL3, specifically those that play crucial roles in amino acid biosynthesis and metabolism in P. falciparum. Taken together, this study highlights PfUCHL3 as a previously undisclosed druggable target of HF, which contributes to the development of novel anti-malarial agents in the future.

Multifunctional sprayable carboxymethyl chitosan/polyphenol hydrogel for wound healing.

The use of facile methods to synthesize environmentally friendly and multifunctional hydrogel dressings is still a major challenge in development. Herein, Turkish gall extract (TGE) and carboxymethyl chitosan (CMCS) were combined and sprayed using a dual syringe to form a multifunctional TGE-CMCS hydrogel (TC gel) in one step through abundant hydrogen bonding between functional groups as a green approach. TC gel showed rapid gelation at 19.0 ± 2.9 s. Apart from the advantage of being able to adapt to different wound shapes, TC gel retained the antioxidant, antibacterial, hemostatic and anti-inflammatory properties of TGE. In vitro antibacterial experiments showed that TC-gel eliminated 98.27 ± 0.79 % of Staphylococcus aureus and 98.87 ± 1.08 % of Escherichia coli. Compared with TGE or CMCS alone, TC gel accelerates skin wound healing due to its three-dimensional network structure and continuous release of active components at the wound site, enhancing re-epithelialization, improving collagen deposition, and increasing angiogenesis. The wound healing rate of full-thickness skin defect rats treated with TC gel was 93.98 ± 0.63 % on the 10th day. These results suggest that TC gel combined with a facile and scalable manufacturing method is a promising multifunctional wound dressing for clinical wound management.

Enhanced optical imaging and fluorescent labeling for visualizing drug molecules within living organisms.

The visualization of drugs in living systems has become key techniques in modern therapeutics. Recent advancements in optical imaging technologies and molecular design strategies have revolutionized drug visualization. At the subcellular level, super-resolution microscopy has allowed exploration of the molecular landscape within individual cells and the cellular response to drugs. Moving beyond subcellular imaging, researchers have integrated multiple modes, like optical near-infrared II imaging, to study the complex spatiotemporal interactions between drugs and their surroundings. By combining these visualization approaches, researchers gain supplementary information on physiological parameters, metabolic activity, and tissue composition, leading to a comprehensive understanding of drug behavior. This review focuses on cutting-edge technologies in drug visualization, particularly fluorescence imaging, and the main types of fluorescent molecules used. Additionally, we discuss current challenges and prospects in targeted drug research, emphasizing the importance of multidisciplinary cooperation in advancing drug visualization. With the integration of advanced imaging technology and molecular design, drug visualization has the potential to redefine our understanding of pharmacology, enabling the analysis of drug micro-dynamics in subcellular environments from new perspectives and deepening pharmacological research to the levels of the cell and organelles.

Recent advances in neuroinflammation prevention and therapy: the role of natural products and underlying mechanisms based on molecular targets.

Neuroinflammation is initiated in response to a variety of endogenous and exogenous sources. As the resident macrophages of the central nervous system, the polarization of microglia into either the M1 pro-inflammatory phenotype or the M2 anti-inflammatory phenotype holds great promise as a therapeutic strategy for neuroinflammation. Natural products, comprising a vital chemical library with distinctive structures and diverse functions, have been extensively employed to modulate microglial polarization for the treatment of neuroinflammation. In this review, we present up-to-date and extensive insights into the therapeutic effects and underlying mechanisms of natural products in the context of neuroinflammation. Furthermore, the review aims to present a new perspective by focusing on the targets of natural compounds, elucidating the molecular mechanisms and guiding the transition from natural-derived lead compounds to potential anti-neuroinflammatory drugs. Additionally, we provide a comprehensive overview of the challenges and limitations associated with the utilization of natural products for neuroinflammation therapy.

Erratum: Author correction to 'Pharmacologically targeting molecular motor promotes mitochondrial fission for anti-cancer' [Acta Pharm Sin B 11 (2021) 1853-1866].

[This corrects the article DOI: 10.1016/j.apsb.2021.01.011.].

Small-molecule targeting PKM2 provides a molecular basis of lactylation-dependent fibroblast-like synoviocytes proliferation inhibition against rheumatoid arthritis.

Fibroblast-like synoviocytes (FLS) play an important role in rheumatoid arthritis (RA)-related swelling and bone damage. Therefore, novel targets for RA therapy in FLS are urgently discovered for improving pathologic phenomenon, especially joint damage and dyskinesia. Here, we suggested that pyruvate kinase M2 (PKM2) in FLS represented a pharmacological target for RA treatment by antimalarial drug artemisinin (ART). We demonstrated that ART selectively inhibited human RA-FLS and rat collagen-induced arthritis (CIA)-FLS proliferation and migration without observed toxic effects. In particular, the identification of targets revealed that PKM2 played a crucial role as a primary regulator of the cell cycle, leading to the heightened proliferation of RA-FLS. ART exhibited a direct interaction with PKM2, resulting in an allosteric modulation that enhances the lactylation modification of PKM2. This interaction further promoted the binding of p300, ultimately preventing the nuclear translocation of PKM2 and inducing cell cycle arrest at the S phase. In vivo, ART obviously suppressed RA-mediated synovial hyperplasia, bone damage and inflammatory response to further improve motor behavior in CIA-rats. Taken together, these findings indicate that directing interventions towards PKM2 in FLS could offer a hopeful avenue for pharmaceutical treatments of RA through the regulation of cell cycle via PKM2 lactylation.

Thermal Proteome Profiling Strategy Identifies CNPY3 as a Cellular Target of Gambogic Acid for Inducing Prostate Cancer Pyroptosis.

There is an urgent requirement to acquire a comprehensive comprehension of novel therapeutic targets for prostate cancer to facilitate the development of medications with innovative mechanisms. In this study, we identified gambogic acid (GBA) as a specific pyroptosis inducer in prostatic cancer cells. By using a thermal proteome profiling (TPP) strategy, we revealed that GBA induces pyroptosis by directly targeting the canopy FGF signaling regulator (CNPY3), which was previously considered "undruggable". Moreover, through the utilization of the APEX2-based proximity labeling method, we found that GBA recruited delactatease SIRT1, resulting in the elimination of lysine lactylation (Kla) on CNPY3. Of note, SIRT1-mediated delactylation influenced the cellular localization of CNPY3 to promote lysosome rupture for triggering pyroptosis. Taken together, our study identified CNPY3 as a distinctive cellular target for pyroptosis induction and its potential application in prostate cancer therapy.

Cayratia albifolia C.L.Li exerts anti-rheumatoid arthritis effect by inhibiting macrophage activation and neutrophil extracellular traps (NETs).

BACKGROUND: Cayratia albifolia C.L.Li (CAC), commonly known as "Jiao-Mei-Gu" in China, has been extensively utilized by the Dong minority for several millennia to effectively alleviate symptoms associated with autoimmune diseases. CAC extract is believed to possess significant anti-inflammatory properties within the context of Dong medicine. However, an in-depth understanding of the specific pharmaceutical effects and underlying mechanisms through which CAC extract acts against rheumatoid arthritis (RA) has yet to be established. METHODS: Twenty-four Sprague-Dawley rats were divided into four groups, with six rats in each group. To induce the collagen-induced arthritis (CIA) model, the rats underwent a process of double immunization with collagen and adjuvant. CAC extract (100 mg/kg) was orally administered to rats. The anti-RA effects were evaluated in CIA rats by arthritis score, hind paw volume and histopathology analysis. Pull-down assay was conducted to identify the potential targets of CAC extract from RAW264.7 macrophage lysates. Moreover, mechanism studies of CAC extract were performed by immunofluorescence assays, real-time PCR and Western blot. RESULTS: CAC extract was found to obviously down-regulate hind paw volume of CIA rats, with diminished inflammation response and damage. 177 targets were identified from CAC extract by MS-based pull-down assay. Bioinformatics analysis found that these targets were mainly enriched in macrophage activation and neutrophils extracellular traps (NETs). Additionally, we reported that CAC extract owned significant anti-inflammatory activity by regulating PI3K-Akt-mTOR signal pathway, and inhibited NETosis in response to PMA. CONCLUSIONS: We clarified that CAC extract significantly attenuated RA by inactivating macrophage and reducing NETosis via a multi-targets regulation.

Mercuric sulfide nanoparticles suppress the neurobehavioral functions of Caenorhabditis elegans through a Skp1-dependent mechanism.

Cinnabar is the naturally occurring mercuric sulfide (HgS) and concerns about its safety have been grown. However, the molecular mechanism of HgS-related neurotoxicity remains unclear. S-phase kinase-associated protein 1 (Skp1), identified as the target protein of HgS, plays a crucial role in the development of neurological diseases. This study aims to investigate the neurotoxic effects and molecular mechanism of HgS based on Skp1 using the Caenorhabditis elegans (C. elegans) model. We prepared the HgS nanoparticles and conducted a comparative analysis of neurobehavioral differences in both wild-type C. elegans (N2) and a transgenic strain of C. elegans (VC1241) with a knockout of the SKP1 homologous gene after exposure to HgS nanoparticles. Our results showed that HgS nanoparticles could suppress locomotion, defecation, egg-laying, and associative learning behaviors in N2 C. elegans, while no significant alterations were observed in the VC1241 C. elegans. Furthermore, we conducted a 4D label-free proteomics analysis and screened 504 key proteins significantly affected by HgS nanoparticles through Skp1. These proteins play pivotal roles in various pathways, including SNARE interactions in vesicular transport, TGF-beta signaling pathway, calcium signaling pathway, FoxO signaling pathway, etc. In summary, HgS nanoparticles at high doses suppress the neurobehavioral functions of C. elegans through a Skp1-dependent mechanism.

Anti-psoriasis molecular targets and active components discovery of Optimized Yinxieling Formula via affinity-purified strategy.

Psoriasis, a prevalent inherited skin condition, involves an inflammatory response as a key pathogenic mechanism. The Optimized Yinxieling Formula (OYF), rooted in traditional Chinese medicine, is extensively utilized in clinical settings to treat psoriasis. Although previous studies have demonstrated OYF's significant anti-inflammatory effects in psoriasis, its potential molecular targets and active components remain unexplored. This study aimed to unveil the anti-psoriasis molecular targets and active components of OYF. Our findings indicated that OYF extract markedly reduced the production of several inflammatory mediators, including IL-23, nitric oxide, TNF-α, and IL-1ß, in LPS-induced RAW264.7 cells. We synthesized OYF extract-crosslinked beads to isolate pharmacological targets from RAW264.7 lysates using an affinity purification strategy, known as Target Fishing. The enriched target proteins were subsequently identified via LC-MS/MS, followed by bioinformatics analysis to map the psoriasis-associated pathway-gene network. We identified a total of 76 potential target proteins, which were highly associated with mRNA transcription mechanisms. In particular, pathway-gene network analysis revealed that the IL-23 inflammatory pathway was involved in the anti-psoriasis effect of OYF extract. We further utilized a target protein-based affinity capture strategy, combined with LC-MS and SPR analysis, to globally screen OYF's active components, focusing on the mRNA transcription regulator, fused in sarcoma (FUS). This process led to the identification of umbelliferone, vanillic acid, protocatechuic acid, gentisic acid, and echinacoside as key compounds targeting FUS to inhibit IL-23 expression. Additionally, we formulated a compound cocktail (CpdC), which significantly reduced psoriasis area and severity index (PASI) scores and the expressions of IL-23 and Ki67 in an imiquimod (IMQ)-induced psoriasis mouse model. Collectively, our study elucidates the primary molecular targets and active components of OYF, offering novel insights for psoriasis treatment.

Palmitoylation of PKCδ by ZDHHC5 in hypothalamic microglia presents as a therapeutic target for fatty liver disease.

The hypothalamus plays a fundamental role in controlling lipid metabolism through neuroendocrine signals. However, there are currently no available drug targets in the hypothalamus that can effectively improve human lipid metabolism. In this study, we found that the antimalarial drug artemether (ART) significantly improved lipid metabolism by specifically inhibiting microglial activation in the hypothalamus of high-fat diet-induced mice. Mechanically, ART protects the thyrotropin-releasing hormone (TRH) neurons surrounding microglial cells from inflammatory damage and promotes the release of TRH into the peripheral circulation. As a result, TRH stimulates the synthesis of thyroid hormone (TH), leading to a significant improvement in hepatic lipid disorders. Subsequently, we employed a biotin-labeled ART chemical probe to identify the direct cellular target in microglial cells as protein kinase Cδ (PKCδ). Importantly, ART directly targeted PKCδ to inhibit its palmitoylation modification by blocking the binding of zinc finger DHHC-type palmitoyltransferase 5 (ZDHHC5), which resulted in the inhibition of downstream neuroinflammation signaling. In vivo, hypothalamic microglia-specific PKCδ knockdown markedly impaired ART-dependent neuroendocrine regulation and lipid metabolism improvement in mice. Furthermore, single-cell transcriptomics analysis in human brain tissues revealed that the level of PKCδ in microglia positively correlated with individuals who had hyperlipemia, thereby highlighting a clinical translational value. Collectively, these data suggest that the palmitoylation of microglial PKCδ in the hypothalamus plays a role in modulating peripheral lipid metabolism through hypothalamus-liver communication, and provides a promising therapeutic target for fatty liver diseases.

Icaritin Sensitizes Thrombin- and TxA2-Induced Platelet Activation and Promotes Hemostasis via Enhancing PLCγ2-PKC Signaling Pathways.

BACKGROUND: Vascular injury results in uncontrollable hemorrhage in hemorrhagic diseases and excessive antithrombotic therapy. Safe and efficient hemostatic agents which can be orally administered are urgently needed. Platelets play indispensable roles in hemostasis, but there is no drug exerting hemostatic effects through enhancing platelet function. METHODS: The regulatory effects of icaritin, a natural compound isolated from Herba Epimedii, on the dense granule release, thromboxane A2 (TxA2) synthesis, α-granule release, activation of integrin αIIbß3, and aggregation of platelets induced by multiple agonists were investigated. The effects of icaritin on tail vein bleeding times of warfarin-treated mice were also evaluated. Furthermore, we investigated the underlying mechanisms by which icaritin exerted its pharmacological effects. RESULTS: Icaritin alone did not activate platelets, but significantly potentiated the dense granule release, α-granule release, activation of integrin αIIbß3, and aggregation of platelets induced by thrombin and U46619. Icaritin also shortened tail vein bleeding times of mice treated with warfarin. In addition, phosphorylated proteome analysis, immunoblotting analysis, and pharmacological research revealed that icaritin sensitized the activation of phospholipase Cγ2 (PLCγ2)-protein kinase C (PKC) signaling pathways, which play important roles in platelet activation. CONCLUSION: Icaritin can sensitize platelet activation induced by thrombin and TxA2 through enhancing the activation of PLCγ2-PKC signaling pathways and promote hemostasis, and has potential to be developed into a novel orally deliverable therapeutic agent for hemorrhages.

Identification of Skp1 as a target of mercury sulfide for neuroprotection.

Mercury sulfide (HgS) exerts extensive biological effects on neuronal function. To investigate the direct target of HgS in neuronal cells, we developed a biotin-tagged HgS probe (bio-HgS) and employed an affinity purification technique to capture its target proteins. Then, we identified S-phase kinase-associated protein 1 (Skp1) as a potential target of HgS. Unexpectedly, we discovered that HgS covalently binds to Skp1 through a "Cys62-HgS-Cys120" mode. Moreover, our findings revealed that HgS inhibits the ubiquitin-protease system through Skp1 to up-regulate SNAP-25 expression, thereby triggering synaptic vesicle exocytosis to regulate locomotion ability in C. elegans. Collectively, our findings may promote a comprehensive interpretation of the pharmacological mechanism of mercury sulfide on neuroprotective function.

Allosteric regulation of the lid domain of PCK2 as a novel strategy for modulating mitochondrial dynamics.

Aberrant PCK2 overexpression has been linked to an unfavorable prognosis and shorter survival, particularly in hepatocellular carcinoma (HCC). Thus, the inactivation of PCK2 provides a promising strategy for HCC treatment. In this study, we used a chemical genetic strategy to identify a natural-derived small-molecule cucurbitacin B (CuB) as a selective PCK2 inhibitor. CuB covalently bound to PCK2 at a unique Cys63 site, blocking the Ω-loop lid domain formation via a previously undisclosed allosteric mechanism. Additionally, targeted lipidomics analysis also revealed that CuB destroyed mitochondrial membrane integrity, leading to the disruption of mitochondrial fusion-fission dynamics. Taken together, this study highlights the discovery of a small-molecule CuB, which reprograms lipid metabolism for controlling mitochondrial dynamics via targeting PCK2 in cancer cells.

Lycorine promotes IDH1 acetylation to induce mitochondrial dynamics imbalance in colorectal cancer cells.

Isocitrate dehydrogenase (IDH) 1 and 2, as essential enzymes in energy metabolism, contribute to the survival and drug resistance of a variety of solid tumors, especially for colorectal cancer (CRC). However, the underlying molecular mechanism still remains unclear. In this study, IDH1 was identified as a crucial cellular target of a natural-derived anti-CRC small molecule lycorine, using the unbiased thermal proteome profiling (TPP) strategy. We found that lycorine directly targeted a unique C-terminal domain of IDH1, and disrupted IDH1 interaction with deacetylase sirtuin 1 (SIRT1), thereby significantly promoting IDH1 acetylation modification. Then, lycorine noticeably triggered oxidative stress in CRC cells to cause mitochondrial membranes injury, and subsequently facilitated mitochondrial fission. Specific knockdown of IDH1 or SIRT1 markedly aggrieved lycorine-mediated oxidative stress and mitochondrial fragmentation in CRC cells. Furthermore, the combination of lycorine and sirtuins blocker nicotinamide (NAM) exhibited a synergic therapeutic effect in CRC cells. Collectively, our results reveal that IDH1 may serve as a promising therapeutic target for CRC via pharmacologically driving oxidative stress-dependent mitochondrial dynamics imbalance.

Pterostilbene participates in TLR4- mediated inflammatory response and autophagy-dependent Aß1-42 endocytosis in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD), the most prevalent form of dementia, remains untreatable. One of the factors that contributes to its progression is microglia-mediated inflammation. Pterostilbene, a compound isolated from Chinese dragon's blood, can reduce inflammation caused by overactive microglia. However, its effects on AD transgenic animals and the possible underlying mechanism remain unknown. METHODS: We evaluated the effect of pterostilbene on learning and memory difficulties in transgenic APP/PS1 mice. We used immunofluorescence to detect microglial activation and Aß aggregation. We explored the cellular mechanism of pterostilbene by establishing LPS- stimulated BV2 cells and oAß1-42- exposed HEK 293T cells that overexpress TLR4 and/or MD2 via lentivirus. We applied flow cytometry and immunoprecipitation to examine how pterostilbene regulates TLR4 signaling. RESULTS: Pterostilbene enhanced the learning and memory abilities of APP/PS1 mice and reduced microglial activation and Aß aggregation in their hippocampus. Pterostilbene alleviated oAß1-42-induced inflammation, which required the involvement of MD2. Pterostilbene disrupted the binding between TLR4 and MD2, which may further prevent TLR4 dimerization and subsequent inflammatory response. Moreover, pterostilbene restored the impaired endocytosis of oAß1-42 through an autophagy-dependent mechanism. CONCLUSION: This is the first demonstration that pterostilbene can potentially treat AD by blocking the interaction of TLR4 and MD2, thereby suppressing TLR4-mediated inflammation.

Exploring the Mechanism of Hepatotoxicity Induced by Dictamnus dasycarpus Based on Network Pharmacology, Molecular Docking and Experimental Pharmacology.

The root bark of Dictamnus dasycarpus Turcz is a traditional Chinese medicine, Dictamni Cortex (DC), which is mainly used in the clinical treatment of skin inflammation, eczema, rubella, rheumatism, and gynecological inflammation. Unexpectedly, there are some cases of liver injury after the administration of DC. However, the mechanism of hepatotoxicity remains ambiguous. The aim of this study was to explore the mechanism and substance bases of DC hepatotoxicity based on network pharmacology and molecular docking, verified through pharmacological experiments. Partial prototype components and metabolites in vivo of quinoline alkaloids from DC were selected as candidate compounds, whose targets were collected from databases. Network pharmacology was applied to study the potential hepatotoxic mechanism after correlating the targets of candidate compounds with the targets of hepatotoxicity. Molecular docking was simulated to uncover the molecular mechanism. Furthermore, the hepatotoxicity of the extract and its constituents from DC was evaluated in vivo and in vitro. We constructed the "potential toxic components-toxic target-toxic pathway" network. Our results showed that the targets of DC included CYP1A2 and GSR, participating in heterologous steroid metabolism, REDOX metabolism, drug metabolism, heterocyclic metabolic processes, the synthesis of steroid hormone, cytochrome P450 metabolism, chemical carcinogens and bile secretion pathways. In vitro and in vivo experiments displayed that DC could result in a decrease in GSH-Px and oxidative stress, simultaneously inhibiting the expression of CYP1A2 and inducing hepatotoxicity. These results further indicated the mechanism of hepatotoxicity induced by Dictamnus dasycarpus, providing a basic theory to explore and prevent hepatotoxicity in the clinical usage of Dictamnus dasycarpus.

Anti-inflammatory quinoline-4(1H)-one derivatives from the aerial parts of Waltheria indica linn.

Eight previously undescribed quinoline-4(1H)-one derivatives (1-8) and five known analogues (9-13) were isolated from the 95% aqueous extract of the aerial parts of Waltheria indica Linn. Their chemical structures were determined by analyzing 1D NMR, 2D NMR and HRESIMS data comprehensively. Compounds 1-8 possess diverse side chains at C-5 of quinoline-4(1H)-one or tetrahydroquinolin-4(1H)-one skeleton. The absolute configurations were assigned via comparison of the experimental and calculated ECD spectra, and analysis of the ECD data of the in situ formed [Rh2(OCOCF3)4] complex. Additionally, all 13 isolated compounds were evaluated for their anti-inflammatory activities by measuring the inhibitory effects of nitric oxide (NO) production in lipopolysaccharide-induced BV-2 cells. Compounds 2, 5 and 11 showed moderate inhibition toward NO production with IC50 values of 40.41 ± 1.01, 60.09 ± 1.23 and 55.38 ± 0.52 µM, respectively.

High resolution micro-confocal Raman spectrometer-based photo-affinity microarray technology for the investigation of active ingredients - Target protein recognition strategy.

Natural products has been used for the prevention and treatment of diseases for a long history. Research on the bioactive components from natural products and their interaction with target proteins are essential for drug discovery. However, studying the binding ability of natural products' active ingredients to target proteins is usually time-consuming and laborious due to their complex and diverse chemical structures. In this study, we have developed a high resolution micro-confocal Raman spectrometer-based photo-affinity microarray (HRMR-PM) technology for the investigation of active ingredients-target protein recognition strategy. The novel photo-affinity microarray was constructed by photo-cross-linking the small molecule with the photo-affinity group (4-[3-(Trifluoromethyl)-3H-diazirin-3-yl]benzoic acid, TAD) on the photo-affinity linker coated (PALC) slides under 365 nm ultraviolet irradiation. The small molecules on the microarrays with specific binding ability might immobilize target protein, which were characterized by high resolution micro-confocal Raman spectrometer. Using this method, more than a dozen components of Shenqi Jiangtang granules (SJG) were made into small molecule probe (SMP) microarrays. As a result, 8 of them had been identified to have α-glucosidase binding ability according to characteristic Raman shift at about 3060 cm-1. These compounds were further verified by different small molecule-protein interaction analysis methods, including contact angle D-value, surface plasmon resonance (SPR) and molecular docking. The results showed that Ginsenosides Mb, Formononetin and Gomisin D exhibited the strongest binding ability. In conclusion, the HRMR-PM strategy for investigating the interaction between target proteins and small molecules has the advantages such as high throughput, low sample consumption and fast qualitative characterization. This strategy is universal which can be applied in the study of in vitro binding activity of various types of small molecules to target proteins.

Usenamine A induces apoptosis and autophagic cell death of human hepatoma cells via interference with the Myosin-9/actin-dependent cytoskeleton remodeling.

BACKGROUND: Hepatocellular carcinoma (HCC) is a major cause of cancer-associated mortality worldwide. Myosin-9's role in HCC and the anti-HCC effect of the drugs targeting Myosin-9 remain poorly understood so far. Candidate antitumor agents obtained from natural products have attracted worldwide attention. Usenamine A is a novel product, which was first extracted in our laboratory from the lichen Usnea longissima. According to published reports, usenamine A exhibits good antitumor activity, while the mechanisms underlying its antitumor effects remain to be elucidated. PURPOSE: The present study investigated the anti-hepatoma effect of usenamine A and the underlying molecular mechanisms, along with evaluating the therapeutic potential of targeting Myosin-9 in HCC. METHODS: The CCK-8, Hoechst staining, and FACS assays were conducted in the present study to investigate how usenamine A affected the growth and apoptosis of human hepatoma cells. Moreover, TEM, acridine orange staining, and immunofluorescence assay were performed to explore the induction of autophagy by usenamine A in human hepatoma cells. The usenamine A-mediated regulation of protein expression in human hepatoma cells was analyzed using immunoblotting. MS analysis, SPR assay, CETSA, and molecular modeling were performed to identify the direct target of usenamine A. Immunofluorescence assay and co-immunoprecipitation assay were conducted to determine whether usenamine A affected the interaction between Myosin-9 and the actin present in human hepatoma cells. In addition, the anti-hepatoma effect of usenamine A was investigated in vivo using a xenograft tumor model and the IHC analysis. RESULTS: The present study initially revealed that usenamine A could suppress the proliferation of HepG2 and SK-HEP-1 cells (hepatoma cell lines). Furthermore, usenamine A induced cell apoptosis via the activation of caspase-3. In addition, usenamine A enhanced autophagy. Moreover, usenamine A administration could dramatically suppress the carcinogenic ability of HepG2 cells, as evidenced by the nude mouse xenograft tumor model. Importantly, it was initially revealed that Myosin-9 was a direct target of usenamine A. Usenamine A could block cytoskeleton remodeling through the disruption of the interaction between Myosin-9 and actin. Myosin-9 participated in suppressing proliferation while inducing apoptosis and autophagy in response to treatment with usenamine A. In addition, Myosin-9 was revealed as a potential oncogene in HCC. CONCLUSIONS: Usenamine A was initially revealed to suppress human hepatoma cells growth by interfering with the Myosin-9/actin-dependent cytoskeleton remodeling through the direct targeting of Myosin-9. Myosin-9 is, therefore, a promising candidate target for HCC treatment, while usenamine A may be utilized as a possible anti-HCC therapeutic, particularly in the treatment of HCC with aberrant Myosin-9.