Acta Pharmacologica Sinica最新文献

Immunotherapy has shown limited efficacy in hepatocellular carcinoma (HCC) due to the immunosuppressive tumor microenvironment (TME). Previous studies show that asiatic acid (AA), a naturally occurring pentacyclic triterpenoid, exhibits potent inhibitory effects on tumor cell proliferation. In this study we investigated the effects of AA on the TME and immunotherapy in HCC. Both subcutaneous and orthotopic HCC models were established in male mice. The mice were treated with AA (50 mg·kg⁻¹·d⁻¹, i.g) for two weeks. At the experimental endpoint, mice were euthanized, and tumor-infiltrating immune cell populations were analyzed using flow cytometry. We showed that AA treatment effectively converted "cold tumors" into "hot tumors" by promoting CD8⁺ T cell infiltration and activation in HCC. We demonstrated that AA non-covalently bound and inhibited histone deacetylase 8 (HDAC8), increasing H3K27 acetylation at the CXCL10 promoter to enhance its expression. This epigenetic reprogramming elevated CXCL10 expression and drove robust CD8⁺ T cell recruitment. HDAC8 overexpression abolished these effects, confirming the target specificity. Importantly, we demonstrated that AA synergized with anti-PD-L1 therapy while maintaining a favorable safety profile. This study identifies AA as a novel HDAC8 inhibitor that remodels the TME, offering a promising strategy to overcome immunotherapy resistance in HCC.

The incidence of digestive system diseases is increasing, with liver diseases, obesity, inflammatory bowel disease (IBD), and hepatoenteric cancers being prominent contributors to global morbidity and mortality. Targeting farnesoid X receptor (FXR) has emerged as a promising therapeutic strategy for various digestive disorders. FXR is a member of the nuclear receptor superfamily, is expressed primarily in the liver and small intestine, and is activated by bile acids (BAs). Beyond classical ligand-dependent activation, FXR activity is precisely modulated by epigenetic regulation and posttranslational modifications (PTMs), such as DNA methylation, histone methylation and acetylation, noncoding RNA regulation, phosphorylation, acetylation, SUMOylation, ubiquitination, O-glycosylation, methylation, sulfhydration, and poly(ADP-ribosyl)ation. Growing evidence reveals disease-associated alterations in FXR modification patterns, offering novel therapeutic perspectives for digestive pathologies. In this review, we comprehensively summarize the structure of FXR, its regulatory mechanisms through epigenetic modifications and PTMs, and its potential application in the treatment of digestive diseases. The structure of FXR, its regulatory mechanisms through epigenetic modifications and PTMs, and its potential application in the treatment of digestive diseases. Upper: epigenetic regulation of FXR. Below: posttranslational modifications of FXR. OG O-glycosylation, P phosphorylation, SUMO SUMOylation, SSH sulfhydration, Ac acetylation, Me methylation, Ub ubiquitination.

Prolactin-releasing peptide (PrRP) is an endogenous ligand for the PrRPR, whose activation has been linked to anti-obesity effects. However, PrRP and its analogs also activate the neuropeptide FF receptor 2 (NPFF2R), which is associated with adverse cardiovascular effects. Understanding how PrRP-related peptides differentially engage these two distinct receptors is critical for developing safer, more selective therapeutics. In this study, we present cryo-EM structures of the PrRP analog GUB08248 bound to PrRPR-Gα_q and NPFF2R-Gα_i at resolutions of 2.45 Å and 2.85 Å, respectively. These structures reveal a conserved ligand recognition mode across both receptors, while highlighting distinct receptor-specific interactions. The NPFF2R-Gα_i complex further uncovers key features of receptor activation and G protein coupling. Together, our results offer structural insights that could guide structure-based drug design strategies favoring PrRPR selectivity, thereby advancing the therapeutic potential of the PrRP-PrRPR axis for obesity treatment.

Carboxylesterases CES1 and CES2 are the pivotal hepatic enzymes involved in triglyceride (TG) hydrolysis and prodrug metabolism, yet their expression and activity are suppressed in metabolic dysfunction-associated steatotic liver disease (MASLD). Liver X receptor alpha (LXRα) is known to play a crucial role in maintaining the constitutive expression of CES1 in human liver cells. Oridonin (ORI) is a diterpene derived from a traditional Chinese herb that possesses antitumor, anti-inflammatory, and antimicrobial activities. We previously demonstrated that ORI, as a natural LXRα agonist, activated the LXRα-ATGL/EPT1 pathway, correcting the TG/phosphatidylethanolamine (PE) lipid imbalance induced by obesity and thereby improving MASLD. Here, we investigated the regulatory role of LXRα on CES1/CES2 expression in MASLD liver and elucidated the underlying molecular mechanisms of ORI's lipid-lowering effects. A high-fat diet (HFD)-induced steatosis model was established in mice. The mice were treated with ORI (100 mg·kg^-1·d^-1, i.g.) from the 16th to the 24th week. RNA-seq analysis in MASLD patients demonstrated that LXRα is a key transcriptional regulator of CES1 and CES2. LXRα knockout (LXRα^-/-) mice exhibited aggravated HFD-induced steatosis and impaired metabolic conversion of the CES1/CES2 substrates, oseltamivir and irinotecan. This deficiency resulted in a corresponding increase in their drug exposure (AUC) by 154.5% and 26.2%, respectively. Mechanistically, LXRα directly bound to liver X receptor response elements (LXREs) in the promoter regions of CES1 (-183/-165 bp) and CES2 (-1870/-1852 bp) to drive transcription in HepG2 cells. Furthermore, ORI (2.5, 5, 10 μM) dose-dependently restored CES1/CES2 expression and activity, reducing lipid accumulation. Silencing of CES1 or CES2 abolished ORI's lipid-lowering effect, confirming their essential roles. These findings establish the LXRα-CES1/CES2 pathway as a pivotal node integrating hepatic lipid homeostasis and drug metabolism, positioning ORI as a promising therapeutic agent for MASLD.

While AlphaFold3 (AF3) extends AlphaFold2 (AF2) by predicting holo structures, it remains unclear whether its modeling process captures similar induced-fit mechanisms. In this study, we benchmarked the VS performance of ligand-induced AF3 holo structures on two datasets: a subset of DUD-E and VsNsBench designed to avoid sequence-level information leakage. On both datasets, AF3 holo structures demonstrated substantially improved enriching capability compared to AF3 apo, experimental apo, and AF2 structures. Compared to experimental holo structures, AF3 models demonstrated inferior performance on the DUD-E subset but performed slightly better on VsNsBench. Further analysis revealed that AF3's induced modeling critically depends on the bound ligand's affinity: high-affinity ligands produced conformations enabling excellent enrichment, while low-affinity or random ligands yielded poor performance. Moreover, direct VS using AF3 alone achieved satisfactory performance, but computational efficiency remains a major bottleneck for large-scale applications, even with single-round multiple sequence alignment (MSA) generation. In a DFG-motif kinase case study, AF3 successfully modeled inhibitor-specific conformations with a 75% success rate. These findings demonstrate that AF3 effectively incorporates induced-fit modeling, though improvement is needed, particularly for modeling multi-state conformational ensembles.

Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat depression, but their chronic use is associated with side effects and residual symptoms of depression. Both effects induced by SSRIs are mediated by serotonin receptor-dependent signaling pathways, yet the molecular mechanisms underlying these effects remain unclear. Here, we investigated the impact of chronic and acute activation of the 5-HT7 receptor (5-HT7R) using the selective agonist AGH-194 in male mice. Behavioral assessment revealed that chronic AGH-194 administration induced depressive-like effects in the novelty suppressed feeding test (NSFT), female urine sniffing test (FUST), and novel object location test (NOLT). After acute injection, depressive-like effects were observed only in NSFT. At the molecular level, AGH-194 administration activated matrix metalloproteinase 9 (MMP-9) through a 5-HT7R-Gαs signaling-dependent mechanism. Acute treatment induced transient activation, while chronic treatment led to prolonged enzymatic activity, accompanied by a reduction in the expression of the GluA1 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in the hippocampus. At the cellular level, acute but not chronic AGH-194 treatment induced a shift toward more juvenile dendritic spine morphology in the CA1 and dentate gyrus (DG) regions of the hippocampus, along with an increase in dendritic spine density in DG. Electrophysiological recordings demonstrated that acute AGH-194 administration enhanced hippocampal excitability by increasing population spike amplitude in CA1. Chronic AGH-194 treatment further modulated short-term plasticity, increasing both population spike and extracellular field potential paired-pulse ratios (PS-PPR and EPSP-PPR) in CA1, while also enhancing the maximum EPSP slope amplitude. These findings provide novel evidence that chronic 5-HT7R activation can induce depressive-like behaviors in male mice, potentially through sustained MMP-9 activation and alterations in synaptic plasticity. Understanding the molecular and electrophysiological consequences of selective 5-HT7R stimulation may provide insights into receptor-specific mechanisms that could contribute to SSRI-induced side effects, thereby contributing to the development of improved antidepressant strategies.

Hypoxia-inducible factor 2-alpha (HIF-2α), a critical transcription factor, forms a heterodimer with aryl hydrocarbon receptor nuclear translocator (ARNT) to drive the transcription of erythropoietin (EPO), a key regulator of erythropoiesis. Activation of this pathway plays a pivotal role in the treatment of anemia. By discovered structure-based virtual screening and pharmacological assays, we herein discovered an amide thiazole AT-1 that bound to HIF-2α with a K_D of 2.63 μM, and enhanced the stability of the HIF-2α-ARNT heterodimer. Molecular docking and site-directed mutagenesis analysis revealed the critical roles of His293 and Tyr307 in the binding of AT-1 to HIF-2α. Pharmacological studies showed that AT-1 (10, 20, 40 μM) dose-dependently enhanced both the transcription and secretion of EPO in 786-O and Hep3B cells. In zebrafish (Danio rerio), AT-1 (10 or 50 μM) exhibited favorable safety profiles and, when combined with the prolyl hydroxylase (PHD) inhibitor Molidustat (10 μM), effectively mitigated doxorubicin-induced anemia. In adenine-induced chronic kidney disease (CKD) mouse model, combined administration of AT-1 (50 mg·kg^-1·d^-1, i.p.) and Molidustat (10 mg·kg^-1·d^-1, i.p.) for 15 days produced stronger effects on increasing EPO levels and alleviating anemia than Molidustat alone, further supporting the therapeutic potential of AT-1 in CKD-related anemia.

Acetaminophen (APAP)-induced acute liver injury (AILI) is primarily driven by CYP3A4‒mediated overproduction of the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI), CYP3A4 activity serves as the rate-limiting determinant of NAPQI accumulation levels. Poly ADP-ribose polymerase 1 (PARP1)-driven ribosylation, a posttranslational modification, has been linked to drug-induced liver injury. PARP1 interacts with pregnane X receptor (PXR), a nuclear receptor that regulates drug-metabolizing enzymes including CYP3A4. In this study we investigated the specific sites of PARP1-mediated PXR ribosylation, particularly regarding their functional relevance to CYP3A4-driven NAPQI biosynthesis in AILI. To establish AILI models, mice were injected with APAP (300 mg·kg^-1, i.p.), liver tissues and serum were collected for analysis 24 h post-injection. In vitro study was conducted in primary hepatocytes isolated from AILI mice and in human hepatic L02 cells exposed to APAP (5, 10, 20 μM). We demonstrated that under AILI conditions, PARP1 catalyzed ribosylation of PXR at the residue E194, forming a PARP1-PXR‒CYP3A4 regulatory axis that amplified oxidative stress and NAPQI accumulation through a positive feedback loop. Specifically, PARP1 was significantly overexpressed in AILI models in vivo and in vitro, and its interaction with PXR was confirmed in immunoprecipitation and proximity biotinylation assays. Molecular dynamics (MD) simulations, mass spectrometry and E194A site-directed mutagenesis revealed that PARP1-mediated ribosylation of PXR E194 enhanced CYP3A4 transcription, ultimately leading to excessive NAPQI production. MD simulations also identified a natural compound schisandrin B (Sch B) that specifically bound to the ligand-binding domain of PXR, induced conformational changes and disrupted the PARP1-PXR interaction interface, thus suppressed the ribosylation. In AILI murine models, administration of Sch B (25, 50, and 100 mg·kg^-1·d^-1, i.g.) for 8 days significantly reduced serum ALT and AST levels, attenuated oxidative stress, and inhibited NAPQI generation by blocking complex formation. This study not only elucidates the mechanisms of PARP1-mediated PXR E194 ribosylation in AILI but also identifies Sch B as the first specific inhibitor of this pathway, providing a theoretical basis for precision detoxification strategies targeting posttranslational modifications.

Myeloid-derived suppressor cells (MDSCs) are a category of immature myeloid cells that have an important function in suppressing immune responses in a variety of pathological settings. Thus, MDSCs are the subject of intensive studies regarding their recruitment, expulsion, deactivation, and maturation promotion. Tumor necrosis factor superfamily member 15 (TNFSF15) is produced largely by vascular endothelial cells in mature blood vessels with expression also observed in tumor-associated macrophages (TAMs) and dendritic cells (DCs) within the tumor stroma. In addition to inhibiting the proliferation of vascular endothelial cells and the differentiation of bone marrow-derived endothelial cell progenitors, TNFSF15 is able to promote the maturation of DC, as well as to modulate the polarization of naive M2-macrophages into M1-macrophages capable of eliminating cancer cells, and activate T-cell. In this study, we investigated whether a recombinant TNFSF15 results in a substantial reduction of MDSC accumulation in Lewis lung cancer (LLC) tumor-bearing mice. LLC allograft model mice were administered recombinant TNFSF15 (5 mg·kg^-1·d^-1, i.p.) for 7 consecutive days. The tumor, bone marrow and spleen were retrieved on Day 8 and analyzed using flow cytometry or immunofluorescence staining. We showed that TNFSF15 treatment significantly inhibited the tumor growth, and caused a substantial reduction of MDSC accumulation in the tumors. The proportions of MDSC in the bone marrows and the spleens were also reduced. The diminished MDSC was mainly the monocyte-like MDSC (M-MDSC) subtype. Additionally, the reduction in M-MDSC population was accompanied by an increase of the proportions of macrophages and DCs in the tumors. We demonstrated that TNFSF15 promoted M-MDSC differentiation by activating the JAK1/STAT3 signaling pathway. Moreover, the treatment gave rise to a markedly escalated accumulation of cytotoxic T cells in the tumors, attributing to tumor growth inhibition. Our results support the view that TNFSF15-driven differentiation of M-MDSC into DCs and macrophages, and the subsequent activation of T cells, may contribute partially to reinstitution of immunity in the tumor microenvironment.

Morphine-6-glucuronide (M6G), the active metabolite of morphine, is currently in clinical development due to its higher analgesic activity. In humans, intravenously administered M6G was predominantly eliminated unchanged through the kidney, whereas it was excreted into the urine as parent drug as well as its metabolites morphine and M3G in normal rats. In bile-duct-cannulated rats, however, bile excretion of the parent drug was the main route of clearance. In the study, we investigated the mechanisms underlying the species differences in vivo disposition of M6G. In hepatocyte uptake assay, we showed that M6G uptake in rat hepatocytes was 75-fold higher than that in human hepatocytes. Hepatic uptake transporter phenotyping study identified M6G as a substrate for rat rOatplal, rOatpla4, rOatp1b2, as well as for human hOATP1B1 and hOATP1B3. Among these, rOatps exhibited significantly stronger uptake of M6G compared to hOATPs. Furthermore, M6G was not a substrate for the canalicular efflux transporters MDR1, hBCRP/rBcrp, hBSEP/rBsep, and hMRP2, but it was recognized by rMrp2. These findings aligned with the observation that M6G exhibited significant biliary excretion in the rat sandwich cultured hepatocyte (SCH) model, but not in the human SCH. Additionally, no species differences were observed in renal uptake mediated by OAT3. Overall, M6G underwent renal clearance in humans via glomerular filtration and active secretion primarily mediated by hOAT3. Although a portion of M6G was also eliminated through the kidney in rats, the majority was subjected to enterohepatic circulation mediated primarily by rOatps and rMrp2, leading to the formation of morphine and M3G, which were subsequently excreted in the urine. The marked difference in the uptake activities of sinusoidal transporters hOATPs/rOatps and the substrate specificity of canalicular transporters hMRP2/rMrp2 were critical factors underlying the species differences in the hepatobiliary disposition of M6G.