Emetine dihydrochloride alleviated radiation-induced lung injury through inhibiting EMT.

Radiation-induced lung injury (RILI), divided into early radiation pneumonia (RP) and late radiation-induced pulmonary fibrosis (RIPF), is a common serious disease after clinical chest radiotherapy or nuclear accident, which seriously threatens the life safety of patients. There has been no effective prevention or treatment strategy till now. Epithelial-mesenchymal transition (EMT) is a key step in the occurrence and development of RILI. In this study, we demonstrated that emetine dihydrochloride (EDD) alleviated RILI through inhibiting EMT. We found that EDD significantly attenuated EMT-related markers, reduced Smad3 phosphorylation expression after radiation. Then, for the first time, we observed EDD alleviated lung hyperaemia and reduced collagen deposit induced by irradiation, providing protection against RILI. Finally, it was found that EDD inhibited radiation-induced EMT in lung tissues. Our study suggested that EDD alleviated RILI through inhibiting EMT by blocking Smad3 signalling pathways. In summary, our results indicated that EDD is a novel potential radioprotector for RILI.

Identification of a derivative of the alkaloid emetine as an inhibitor of the YAP-TEAD interaction and its potential as an anticancer agent.

TEAD is a transcription factor responsible for the output of the tumor suppressor Hippo pathway. The transcriptional activity of TEAD requires molecular interaction with its transcriptional coactivator, YAP. Aberrant activation of TEAD is deeply involved in tumorigenesis and is associated with poor prognosis, suggesting that inhibitors targeting the YAP-TEAD system are promising as antitumor agents. In this study, we identified NPD689, an analog of the natural product alkaloid emetine, as an inhibitor of the YAP-TEAD interaction. NPD689 suppressed the transcriptional activity of TEAD and reduced the viability of human malignant pleural mesothelioma and non-small cell lung cancer cells but not the viability of normal human mesothelial cells. Our results suggest that NPD689 is not only a new useful chemical tool for elucidating the biological role of the YAP-TEAD system but also has potential as a starting compound for developing a cancer therapeutic agent that targets the YAP-TEAD interaction.

Dual action anti-inflammatory/antiviral isoquinoline alkaloids as potent naturally occurring anti-SARS-CoV-2 agents: A combined pharmacological and medicinal chemistry perspective.

In the search for compounds that inhibit the SARS-CoV-2 after the onset of the COVID-19 pandemic, isoquinoline-containing alkaloids have been identified as compounds with high potential to fight the disease. In addition to having strong antiviral activities, most of these alkaloids have significant anti-inflammatory effects which are often manifested through the inhibition of a promising host-based anti-COVID-19 target, the p38 MAPK signaling pathway. In the present review, our pharmacological and medicinal chemistry evaluation resulted in highlighting the potential of anti-SARS-CoV-2 isoquinoline-based alkaloids for the treatment of COVID-19 patients. Considering critical parameters of the antiviral and anti-inflammatory activities, mechanism of action, as well as toxicity/safety profile, we introduce the alkaloids emetine, cephaeline, and papaverine as high-potential therapeutic agents for use in the treatment of COVID-19. Although preclinical studies confirm that some isoquinoline-based alkaloids reviewed in this study have a high potential to inhibit the SARS-CoV-2, their entry into drug regimens of COVID-19 patients requires further clinical trial studies and toxicity evaluation.

Exploring the potential mechanism of emetine against coronavirus disease 2019 combined with lung adenocarcinoma: bioinformatics and molecular simulation analyses.

BACKGROUND: Patients with lung adenocarcinoma (LUAD) may be more predisposed to coronavirus disease 2019 (COVID-19) and have a poorer prognosis. Currently, there is still a lack of effective anti-LUAD/COVID-19 drugs. Thus, this study aimed to screen for an effective anti-LUAD/COVID-19 drug and explore the potential mechanisms. METHODS: Firstly, we performed differentially expressed gene (DEG) analysis on LUAD transcriptome profiling data in The Cancer Genome Atlas (TCGA), where intersections with COVID-19-related genes were screened out. Then, we conducted Cox proportional hazards analyses on these LUAD/COVID-19 DEGs to construct a risk score. Next, LUAD/COVID-19 DEGs were uploaded on Connectivity Map to obtain drugs for anti-LUAD/COVID-19. Finally, we used network pharmacology, molecular docking, and molecular dynamics (MD) simulation to explore the drug's therapeutic targets and potential mechanisms for anti-LUAD/COVID-19. RESULTS: We identified 230 LUAD/COVID-19 DEGs and constructed a risk score containing 7 genes (BTK, CCL20, FURIN, LDHA, TRPA1, ZIC5, and SDK1) that could classify LUAD patients into two risk groups. Then, we screened emetine as an effective drug for anti-LUAD/COVID-19. Network pharmacology analyses identified 6 potential targets (IL6, DPP4, MIF, PRF1, SERPING1, and SLC6A4) for emetine in anti-LUAD/COVID-19. Molecular docking and MD simulation analyses showed that emetine exhibited excellent binding capacities to DDP4 and the main protease (Mpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). CONCLUSIONS: This study found that emetine may inhibit the entry and replication of SARS-CoV-2 and enhance tumor immunity by bounding to DDP4 and Mpro.

Emetine exerts anticancer effects in U2OS human osteosarcoma cells via activation of p38 and inhibition of ERK, JNK, and ß-catenin signaling pathways.

Osteosarcoma (OS) is a primary bone neoplasm that is highly malignant. As advances in chemotherapy for the treatment of OS have stagnated, discovery of new reagents is required. Emetine is a phytochemical which can be isolated from a medicinal herb Cephaelis ipecacuanha and is traditionally used for amoebicides. Previous studies have demonstrated that emetine can possibly be repositioned for use in anticancer reagents. However, any anticancer effects and underlying mechanisms of emetine on human OS are not yet well understood. In this study, we analyzed the anticancer effects and involved cellular mechanisms after treatment with emetine to U2OS human OS cells. Emetine significantly reduced both the viability and proliferation, and induced apoptosis via activation of caspase-3 and caspase-7 in U2OS cells. Emetine effectively inhibited the migration and invasion of U2OS cells. Gelatinase activities of matrix metalloproteinase 2 (MMP-2) and MMP-9 were reduced by emetine. MMP-9 was transcriptionally inhibited, while MMP-2 was posttranscriptionally repressed, via the reduced expression of membrane-type I-matrix metalloproteinase (MT1-MMP). p38, which is closely related with induction of apoptosis, was stimulated by emetine. Extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and ß-catenin, which are linked with expression of MMPs, were downregulated. Emetine exerted anticancer effects on MG63 human OS cells as well. Taken together, our study demonstrated the anticancer and antimetastatic potential of emetine in treating human OS for the first time. It is expected that emetine may be a promising drug candidate to be repositioned for chemotherapy of OS.

Lead Optimization of Dehydroemetine for Repositioned Use in Malaria.

Drug repositioning offers an effective alternative to de novo drug design to tackle the urgent need for novel antimalarial treatments. The antiamoebic compound emetine dihydrochloride has been identified as a potent in vitro inhibitor of the multidrug-resistant strain K1 of Plasmodium falciparum (50% inhibitory concentration [IC50], 47 nM ± 2.1 nM [mean ± standard deviation]). Dehydroemetine, a synthetic analogue of emetine dihydrochloride, has been reported to have less-cardiotoxic effects than emetine. The structures of two diastereomers of dehydroemetine were modeled on the published emetine binding site on the cryo-electron microscopy (cryo-EM) structure with PDB code 3J7A (P. falciparum 80S ribosome in complex with emetine), and it was found that (-)-R,S-dehydroemetine mimicked the bound pose of emetine more closely than did (-)-S,S-dehydroisoemetine. (-)-R,S-dehydroemetine (IC50 71.03 ± 6.1 nM) was also found to be highly potent against the multidrug-resistant K1 strain of P. falciparum compared with (-)-S,S-dehydroisoemetine (IC50, 2.07 ± 0.26 µM), which loses its potency due to the change of configuration at C-1'. In addition to its effect on the asexual erythrocytic stages of P. falciparum, the compound exhibited gametocidal properties with no cross-resistance against any of the multidrug-resistant strains tested. Drug interaction studies showed (-)-R,S-dehydroemetine to have synergistic antimalarial activity with atovaquone and proguanil. Emetine dihydrochloride and (-)-R,S-dehydroemetine failed to show any inhibition of the hERG potassium channel and displayed activity affecting the mitochondrial membrane potential, indicating a possible multimodal mechanism of action.

Identification of Emetine as a Therapeutic Agent for Pulmonary Arterial Hypertension: Novel Effects of an Old Drug.

OBJECTIVE: Excessive proliferation and apoptosis resistance are special characteristics of pulmonary artery smooth muscle cells (PASMCs) in pulmonary arterial hypertension (PAH). However, the drugs in clinical use for PAH target vascular dilatation, which do not exert adequate effects in patients with advanced PAH. Here, we report a novel therapeutic effect of emetine, a principal alkaloid extracted from the root of ipecac clinically used as an emetic and antiprotozoal drug. Approach and Results: We performed stepwise screenings for 5562 compounds from original library. First, we performed high-throughput screening with PASMCs from patients with PAH (PAH-PASMCs) and found 80 compounds that effectively inhibited proliferation. Second, we performed the repeatability and counter assay. Finally, we performed a concentration-dependent assay and found that emetine inhibits PAH-PASMC proliferation. Interestingly, emetine significantly reduced protein levels of HIFs (hypoxia-inducible factors; HIF-1α and HIF-2α) and downstream PDK1 (pyruvate dehydrogenase kinase 1). Moreover, emetine significantly reduced the protein levels of RhoA (Ras homolog gene family, member A), Rho-kinases (ROCK1 and ROCK2 [rho-associated coiled-coil containing protein kinases 1 and 2]), and their downstream CyPA (cyclophilin A), and Bsg (basigin) in PAH-PASMCs. Consistently, emetine treatment significantly reduced the secretion of cytokines/chemokines and growth factors from PAH-PASMCs. Interestingly, emetine reduced protein levels of BRD4 (bromodomain-containing protein 4) and downstream survivin, both of which are involved in many cellular functions, such as cell cycle, apoptosis, and inflammation. Finally, emetine treatment ameliorated pulmonary hypertension in 2 experimental rat models, accompanied by reduced inflammatory changes in the lungs and recovered right ventricular functions. CONCLUSIONS: Emetine is an old but novel drug for PAH that reduces excessive proliferation of PAH-PASMCs and improves right ventricular functions.

Emetine Synergizes with Cisplatin to Enhance Anti-Cancer Efficacy against Lung Cancer Cells.

Cisplatin is still the primary therapeutic choice for advanced lung cancers without driver mutations. The occurrence of cisplatin resistance is a major clinical problem in lung cancer treatment. The natural extracted agent emetine reportedly has anticancer effects. This study aimed to explore the possible role of emetine in cisplatin resistance. We used cell viability, Western blot, and Wnt reporter assays to show that emetine suppresses proliferation, ß-catenin expression, and Wnt/ß-catenin signaling in non-small cell lung cancer (NSCLC). The synergism of emetine and cisplatin was assessed by constructing isobolograms and calculating combination index (CI) values using the Chou-Talalay method. Emetine effectively synergized with cisplatin to suppress the proliferation of cancer cells. Furthermore, nuclear ß-catenin and cancer stem cell-related markers were upregulated in the cisplatin-resistant subpopulation of CL1-0 cells. Emetine enhanced the anticancer efficacy of cisplatin and synergized with cisplatin in the cisplatin-resistant subpopulation of CL1-0 cells. Taken together, these data suggest that emetine could suppress the growth of NSCLC cells through the Wnt/ß-catenin pathway and contribute to a synergistic effect in combination with cisplatin.

Anticancer activities of emetine prodrugs that are proteolytically activated by the prostate specific antigen (PSA) and evaluation of in vivo toxicity of emetine derivatives.

Emetine is a small molecule protein synthesis inhibitor that is toxic to all cell types and therefore suitable for complete killing of all types of heterogeneous cancer cells within a tumor. It becomes significantly inactive (non-toxic) when derivatized at its N-2' secondary amine. This provides a strategy for targeting emetine to cancerous tumor without killing normal cells. In this report, PSA activatable peptide prodrugs of emetine were synthesized. To overcome steric hindrances and enhance protease specific cleavage, a 2-stage prodrug activation process was needed to release emetine in cancer cells. In this 2-stage process, emetine prodrug intermediates are coupled to PSA peptide substrate (Ac-His-Ser-Ser-Lys-Leu-Gln) to obtain the full prodrug. Both prodrug intermediates 10 (Ala-Pro-PABC-Emetine) and 14 (Ser-Leu-PABC-Emetine) were evaluated for kinetics of hydrolysis to emetine and potency [Where PABC = p-aminobenzyloxycarbonyl]. While both intermediates quantitatively liberate emetine when incubated under appropriate conditions, upon coupling of PSA substrate to give the full prodrugs, only prodrug 16, the prodrug obtained from 14 was hydrolyzable by PSA. Cytotoxicity studies in PSA producing LNCaP and CWR22Rv1 confirm the activation of the prodrug by PSA with an IC50 of 75 nM and 59 nM respectively. The cytotoxicity of 16 is significantly reduced in cell lines that do not produce PSA. Further, in vivo toxicity studies are done on these prodrugs and other derivatives of emetine. The results show the significance of conformational modulation in obtaining safe emetine prodrugs.

Iterative design of emetine-based prodrug targeting fibroblast activation protein (FAP) and dipeptidyl peptidase IV DPPIV using a tandem enzymatic activation strategy.

BACKGROUND: There is an urgent need to develop new agents for treating metastatic prostate cancer to overcome multiple drug resistance to the current standard targeted cancer therapy. Emetine is a highly cytotoxic natural product protein synthesis inhibitor, which is toxic to all cell types. Its cytotoxicity can be blocked by derivatizing its N-2' position. Thus emetine can be selectively delivered to cancer cells in the region of metastatic cancer as a prodrug that will be activated by an enzyme selectively overexpressed within the metastatic tumor microenvironment. In this work, we convert emetine to a prodrug activatable by the fibroblast activation protein (FAP), a serine protease overexpressed by the carcinoma associated fibroblasts. METHOD: By using an iterative structure-activity relationship strategy, several peptidyl emetine prodrug analogs (1-11) were synthesized by chemical derivatization of emetine at its N-2' position and tested for in-vitro activation by FAP. The lead prodrug 11 is made up of a DPPIV activatable prodrug precursor 10 (Ala-Pro-PABC-Emetine) coupled to FAP substrate (Ala-Ser-Gly-Pro-Ala-Gly-Pro). Activation assays of the prodrugs were performed in purified FAP, DPPIV, FBS, and human serum and were analyzed by LCMS. In vitro cytotoxicity assays of these prodrugs are carried out in prostate (LNCaP, PC3) and breast (MCF7 and MDA-MB-231) cancer cell lines. The prodrugs are also tested in normal immortalized human prostatic epithelial cell line (PrEC). RESULTS: The lead FAP activated emetine prodrug 11 is activated to emetine in tandem by FAP and DPPIV in about 70% conversion within 24 hr. In prostate and breast cancer cell lines treated with prodrug 11, it is found to be equipotent with emetine in the presence of FAP and DPPIV. However, in the PrEC cell line grown in serum free media, prodrug 11 is more than 200-fold less cytotoxic than emetine in the absence of FAP and DPPIV. CONCLUSION: This FAP activated prodrug of cytotoxic agent emetine further shows the crucial role of the N-2' position of emetine in controlling its cytotoxicity. Significantly reduced toxicity observed in the PrEC cell line in the absence of FAP and DPPIV shows that prodrug 11 could be systemically delivered to regions of metastatic prostate cancer or other solid tumor for activation by cancer selective enzymes within the cancer microenvironment, such as FAP that is overexpressed by the carcinoma-associated fibroblasts. The two-step tandem enzymatic activation of prodrug 11 by FAP and DPPIV is a strategy for overcoming steric hindrance.

Emetine Di-HCl Attenuates Type 1 Diabetes Mellitus in Mice.

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by beta cell destruction, insulin deficiency and hyperglycemia. Activated macrophages and autoimmune T cells play a crucial role in the pathogenesis of hyperglycemia in NOD murine diabetes models, but the molecular mechanisms of macrophage activation are unknown. We recently identified pigment epithelium-derived factor (PEDF) as an adipocyte-derived factor that activates macrophages and mediates insulin resistance. Reasoning that PEDF might participate as a proinflammatory mediator in murine diabetes, we measured PEDF levels in NOD mice. PEDF levels are significantly elevated in pancreas, in correlation with pancreatic TNF levels in NOD mice. To identify experimental therapeutics, we screened 2,327 compounds in two chemical libraries (the NIH Clinical Collection and Pharmakon-1600a) for leads that inhibit PEDF mediated TNF release in macrophage cultures. The lead molecule selected, "emetine" is a widely used emetic. It inhibited PEDF-mediated macrophage activation with an EC50 or 146 nM. Administration of emetine to NOD mice and to C57Bl6 mice subjected to streptozotocin significantly attenuated hyperglycemia, reduced TNF levels in pancreas, and attenuated insulitis. Together, these results suggest that targeting PEDF with emetine may attenuate TNF release and hyperglycemia in murine diabetes models. This suggests that further investigation of PEDF and emetine in the pathogenesis of human diabetes is warranted.

Emetic responses to T-2 toxin, HT-2 toxin and emetine correspond to plasma elevations of peptide YY3-36 and 5-hydroxytryptamine.

Trichothecene mycotoxins are a family of potent translational inhibitors that are associated with foodborne outbreaks of human and animal gastroenteritis in which vomiting is a clinical hallmark. Deoxynivalenol (DON, vomitoxin) and other Type B trichothecenes have been previously demonstrated to cause emesis in the mink (Neovison vison), and this response has been directly linked to secretion of both the satiety hormone peptide YY3-36 (PYY3-36) and neurotransmitter 5-hydroxytryptamine (5-HT). Here, we characterized the emetic responses in the mink to T-2 toxin (T-2) and HT-2 toxin (HT-2), two highly toxic Type A trichothecenes that contaminate cereals, and further compared these effects to those of emetine, a natural alkaloid that is used medicinally and also well known to block translation and cause vomiting. Following intraperitoneal (IP) and oral exposure, all three agents caused vomiting with evident dose-dependent increases in both duration and number of emetic events as well as decreases in latency to emesis. T-2 and HT-2 doses causing emesis in 50 % of treated animals (ED50s) were 0.05 and 0.02 mg/kg BW following IP and oral administration, respectively, whereas the ED50s for emetine were 2.0 and 1.0 mg/kg BW for IP and oral exposure, respectively. Importantly, oral administration of all three toxins elicited marked elevations in plasma concentrations of PYY3-36 and 5-HT that corresponded to emesis. Taken together, the results suggest that T-2 and HT-2 were much more potent than emetine and that emesis induction by all three translational inhibitors co-occurred with increases in circulating levels of PYY3-36 and 5-HT.

Design, synthesis and cytotoxicity studies of dithiocarbamate ester derivatives of emetine in prostate cancer cell lines.

A small library of emetine dithiocarbamate ester derivatives were synthesized in 25-86% yield via derivatization of the N2'- position of emetine. Anticancer evaluation of these compounds in androgen receptor positive LNCaP and androgen receptor negative PC3 and DU145 prostate cancer cell lines revealed time dependent and dose-dependent cytotoxicity. With the exception of compound 4c, all the dithiocarbamate ester analogs in this study showed appreciable potency in all the prostate cancer cell lines (regardless of whether it is androgen receptor positive or negative) with a cytotoxicity IC50 value ranging from 1.312 ± 0.032 µM to 5.201 ± 0.125 µM by day 7 of treatment. Compared to the sodium dithiocarbamate salt 1, all the dithiocarbamate ester analogs (2 and 4a-4 g) displayed lower cytotoxicity than compound 1 (PC3, IC50 = 0.087 ± 0.005 µM; DU145, IC50 = 0.079 ± 0.003 µM and LNCaP, IC50 = 0.079 ± 0.003 µM) on day 7 of treatment. Consequently, it appears that S-alkylation of compound 1 leads to a more stable dithiocarbamate ester derivative that resulted in lower anticancer activity in the prostate cancer cell lines.

Natural Plant Alkaloid (Emetine) Inhibits HIV-1 Replication by Interfering with Reverse Transcriptase Activity.

Ipecac alkaloids are secondary metabolites produced in the medicinal plant Psychotria ipecacuanha. Emetine is the main alkaloid of ipecac and one of the active compounds in syrup of Ipecac with emetic property. Here we evaluated emetine's potential as an antiviral agent against Human Immunodeficiency Virus. We performed in vitro Reverse Transcriptase (RT) Assay and Natural Endogenous Reverse Transcriptase Activity Assay (NERT) to evaluate HIV RT inhibition. Emetine molecular docking on HIV-1 RT was also analyzed. Phenotypic assays were performed in non-lymphocytic and in Peripheral Blood Mononuclear Cells (PBMC) with HIV-1 wild-type and HIV-harboring RT-resistant mutation to Nucleoside Reverse Transcriptase Inhibitors (M184V). Our results showed that HIV-1 RT was blocked in the presence of emetine in both models: in vitro reactions with isolated HIV-1 RT and intravirion, measured by NERT. Emetine revealed a strong potential of inhibiting HIV-1 replication in both cellular models, reaching 80% of reduction in HIV-1 infection, with low cytotoxic effect. Emetine also blocked HIV-1 infection of RT M184V mutant. These results suggest that emetine is able to penetrate in intact HIV particles, and bind and block reverse transcription reaction, suggesting that it can be used as anti-HIV microbicide. Taken together, our findings provide additional pharmacological information on the potential therapeutic effects of emetine.

Emetine dihydrochloride: a novel therapy for bladder cancer.

PURPOSE: Current cisplatin based therapies for stage IV bladder cancer show 4% to 20% 5-year survival, underscoring the need to develop novel therapies for these patients. In the 1970s the natural alkaloid emetine dihydrochloride demonstrated modest anticancer efficacy as a single agent in clinical trials but this was not pursued. Groups recently reported that emetine induced apoptosis in leukemia cell lines, which was enhanced by cisplatin. We determined the antiproliferative effects of emetine with and without cisplatin in bladder cancer cells. MATERIALS AND METHODS: Human bladder cancer cell lines and normal human urothelial cell cultures were treated with emetine and/or cisplatin. We measured cell proliferation and evaluated synergy using the Chou-Talalay method. The combination index was calculated. Cell cycle analysis was done and caspase activation was evaluated to assess growth arrest and apoptosis. RESULTS: Emetine and cisplatin individually inhibited bladder cancer cell proliferation. When combined, emetine and cisplatin acted synergistically to inhibit tumor cell proliferation with combination index values reflecting moderate to strong synergy. Normal urothelial cells were relatively resistant to this treatment. Emetine alone and combined with cisplatin appeared to primarily induce tumor cell growth arrest and not apoptosis. CONCLUSIONS: To our knowledge this study demonstrates for the first time that emetine has in vitro antiproliferative activity against bladder cancer cell lines at nanomolar concentrations but little effect on normal urothelial cells. Moreover, emetine and cisplatin worked synergistically to inhibit tumor cell proliferation. Results suggest that combined emetine and cisplatin based chemotherapy may benefit patients with bladder cancer.

Mechanisms of antiviral action and toxicities of ipecac alkaloids: Emetine and dehydroemetine exhibit anti-coronaviral activities at non-cardiotoxic concentrations.

The emergence of highly infectious pathogens with their potential for triggering global pandemics necessitate the development of effective treatment strategies, including broad-spectrum antiviral therapies to safeguard human health. This study investigates the antiviral activity of emetine, dehydroemetine (DHE), and congeneric compounds against SARS-CoV-2 and HCoV-OC43, and evaluates their impact on the host cell. Concurrently, we assess the potential cardiotoxicity of these ipecac alkaloids. Significantly, our data reveal that emetine and the (-)-R,S isomer of 2,3-dehydroemetine (designated in this paper as DHE4) reduce viral growth at nanomolar concentrations (i.e., IC50 ∼ 50-100 nM), paralleling those required for inhibition of protein synthesis, while calcium channel blocking activity occurs at elevated concentrations (i.e., IC50 ∼ 40-60 µM). Our findings suggest that the antiviral mechanisms primarily involve disruption of host cell protein synthesis and is demonstrably stereoisomer specific. The prospect of a therapeutic window in which emetine or DHE4 inhibit viral propagation without cardiotoxicity renders these alkaloids viable candidates in strategies worthy of clinical investigation.

The Giardia lamblia ribosome structure reveals divergence in several biological pathways and the mode of emetine function.

Giardia lamblia is a deeply branching protist and a human pathogen. Its unusual biology presents the opportunity to explore conserved and fundamental molecular mechanisms. We determined the structure of the G. lamblia 80S ribosome bound to tRNA, mRNA, and the antibiotic emetine by cryo-electron microscopy, to an overall resolution of 2.49 Å. The structure reveals rapidly evolving protein and nucleotide regions, differences in the peptide exit tunnel, and likely altered ribosome quality control pathways. Examination of translation initiation factor binding sites suggests these interactions are conserved despite a divergent initiation mechanism. Highlighting the potential of G. lamblia to resolve conserved biological principles; our structure reveals the interactions of the translation inhibitor emetine with the ribosome and mRNA, thus providing insight into the mechanism of action for this widely used antibiotic. Our work defines key questions in G. lamblia and motivates future experiments to explore the diversity of eukaryotic gene regulation.

Translation stalling induced mitochondrial entrapment of ribosomal quality control related proteins offers cancer cell vulnerability.

Ribosome-associated quality control (RQC) monitors ribosomes for aberrant translation. While the role of RQC in neurodegenerative disease is beginning to be appreciated, its involvement in cancer is understudied. Here, we show a positive correlation between RQC proteins ABCE1 and ZNF598 and high-grade muscle-invasive bladder cancer. Translational stalling by the inhibitor emetine (EME) leads to increased mitochondrial localization of RQC factors including ABCE1, ZNF598, and NEMF, which are continuously imported into mitochondria facilitated by increased mitochondrial membrane potential caused by EME. This reduces the availability of these factors in the cytosol, compromising the effectiveness of RQC in handling stalled ribosomes in the cytosol and those associated with the mitochondrial outer membrane (MOM). Imported RQC factors form aggregates inside the mitochondria in a process we term stalling-induced mitochondrial stress (SIMS). ABCE1 plays a crucial role in maintaining mitochondrial health during SIMS. Notably, cancer stem cells (CSCs) exhibit increased expression of ABCE1 and consequently are more resistant to EME-induced mitochondrial dysfunction. This points to a potential mechanism of drug resistance by CSCs. Our study highlights the significance of mitochondrial entrapment of RQC factors such as ABCE1 in determining the fate of cancer cells versus CSCs. Targeting ABCE1 or other RQC factors in translational inhibition cancer therapy may help overcome drug resistance.

Unveiling FOS as a Potential Diagnostic Biomarker and Emetine as a Prospective Therapeutic Agent for Diabetic Nephropathy.

Background: Diabetic nephropathy (DN) is one of the primary causes of end-stage renal disease, yet effective therapeutic targets remain elusive. This study aims to identify novel diagnostic biomarkers and potential therapeutic candidates for DN. Methods: Differentially expressed genes (DEGs) in GSE96804 and GSE142025 were identified and functional enrichment analysis was performed. Diagnostic biomarkers were selected using machine learning algorithms and evaluated by Receiver Operating Characteristic analysis. c-Fos expression was validated in an established DN mouse model. Immune infiltration levels were assessed with Single-Sample Gene Set Enrichment Analysis. Co-expression analysis revealed regulatory relationships involving FOS. cMAP predicted potential therapeutic candidates. Transcriptome sequencing and experiments in RAW264.7 cells was performed to investigate molecular mechanisms of emetine. Results: In both datasets, we identified 44 upregulated and 74 downregulated DEGs involved in focal adhesion, ECM-receptor interaction, and the PI3K-Akt signaling pathway. FOS emerged as a robust diagnostic marker with decreased expression in DN patients and DN mouse. Co-expression analysis revealed potential regulatory mechanisms of FOS, implicating the MAPK signaling pathway, regulation of cell proliferation and apoptotic signaling pathways. Immune dysregulation was observed in DN patients. Notably, emetine was identified as a potential therapeutic candidate. Transcriptome sequencing and experimental validation demonstrated emetine suppressed M1 macrophage polarization by inhibiting the activation of NF-κB signaling pathway, as well as reducing the expression of Il-18 and Ccl5. Conclusion: In conclusion, our study identified FOS as a promising diagnostic biomarker and emetine as a potential therapeutic candidate for DN. These findings enhance our understanding of DN pathogenesis and present novel prospects for therapeutic strategies.

Emetine, a small molecule natural product, displays potent anti-gastric cancer activity via regulation of multiple signaling pathways.

BACKGROUND: Gastric cancer (GC) is a life-threatening malignant tumor with high incidence rate. Despite great progress, there are still many GC sufferers that cannot benefit from the existing anti-GC treatments. Therefore, it is still necessary to develop novel medicines against GC. Emetine, a natural small molecule isolated from Psychotria ipecacuanha, has been broadly used for medicinal purposes including cancer treatment. Here, we conducted a comprehensive study on the anti-GC effects of emetine and the related mechanisms of action. METHODS: The cell viability was evaluated by MTT and colony formation assay. Cellular proliferation and apoptosis were analyzed by edu incorporation assay and Annexin V-PI staining, respectively. Moreover, wound healing assay and transwell invasion assay were conducted to detect cell migration and invasion after treatment with emetine. To elucidate the molecular mechanism involved in the anti-GC effects of emetine, RNA sequencing and functional enrichment analysis were carried out on MGC803 cells. Then, the western blot analysis was performed to further verify the anti-GC mechanism of emetine. In vivo anti-tumor efficacy of emetine was evaluated in the MGC803 xenograft model. RESULTS: MTT and colony formation assay exhibited a strong potency of emetine against GC cell growth, with IC50 values of 0.0497 µM and 0.0244 µM on MGC803 and HGC-27 cells, respectively. Further pharmacodynamic studies revealed that emetine restrained the growth of GC cells mainly via proliferation inhibition and apoptosis induction. Meanwhile, emetine also had the ability to block GC cell migration and invasion. The results of RNA sequencing and western blot showed that emetine acted through regulating multiple signaling pathways, including not only MAPKs and Wnt/ß-catenin signaling axes, but also PI3K/AKT and Hippo/YAP signaling cascades that were not found in other tumor types. Notably, the antitumor efficacy of emetine could also be observed in MGC803 xenograft models. CONCLUSION: Our data demonstrate that emetine is a promising lead compound and even a potential drug candidate for GC treatment, deserving further structural optimization and development.