• Lythrum salicaria
• Breast cancer
• Green synthesis
• Metal nanoparticles
• Silver

• Humans
• Metal Nanoparticles/chemistry
• Silver/chemistry
• Silver/pharmacology
• Plant Extracts/pharmacology
• Plant Extracts/chemistry
• Breast Neoplasms/drug therapy
• Breast Neoplasms/pathology
• Breast Neoplasms/metabolism
• MCF-7 Cells
• Apoptosis/drug effects
• Green Chemistry Technology/methods
• Reactive Oxygen Species/metabolism
• Female
• HEK293 Cells
• Antineoplastic Agents/pharmacology
• X-Ray Diffraction
• Cell Survival/drug effects

• Arenobufagin
• JNK pathway
• apoptosis
• claspin
• nasopharyngeal carcinoma

• Animals
• Female
• Humans
• Male
• Mice
• Antineoplastic Agents/pharmacology
• Apoptosis/drug effects
• Bufanolides/pharmacology
• Cell Line, Tumor
• Cell Proliferation/drug effects
• Cell Survival/drug effects
• Down-Regulation
• MAP Kinase Signaling System/drug effects
• Mice, Inbred BALB C
• Mice, Nude
• Nasopharyngeal Carcinoma/drug therapy
• Nasopharyngeal Carcinoma/pathology
• Nasopharyngeal Neoplasms/drug therapy
• Nasopharyngeal Neoplasms/pathology
• Xenograft Model Antitumor Assays

• Arenobufagin
• cancer
• drug delivery
• pharmacodynamics
• polymeric micelles

• Alkaliptosis
• Arenobufagin
• Cisplatin
• Gastric cancer

• ATM signaling
• Prunus avium
• chemo-preventive
• hepatocarcinoma
• mRNA expression

• 3,11-bispeptide ester
• antitumor agent
• arenobufagin
• natural product

• Antioxidants
• CRISPR/cas9 system
• Iron metabolism
• Lipid peroxidation
• Traditional medicine

• DNA damage
• arenobufagin
• arsenite
• cell cycle arrest
• cell death
• combination therapy
• gamabufotalin
• glioblastoma

• Antineoplastic Agents/pharmacology
• Apoptosis
• Arsenic/metabolism
• Arsenites/pharmacology
• Bufanolides/pharmacology
• Caspase 8/metabolism
• Caspase 9/metabolism
• Cell Line
• Cell Line, Tumor
• Glioblastoma/drug therapy
• Glioblastoma/metabolism
• Humans

Development of new therapeutic strategies for breast cancer is urgently needed due to the sustained emergence of drug resistance, tumor recurrence and metastasis. To gain a novel insight into therapeutic approaches to fight against breast cancer, the cytocidal effects of hellebrigenin (Helle) and arenobufagin (Areno) were investigated in human estrogen receptor (ER)-positive breast cancer cell line MCF-7 and triple-negative breast cancer cell line MDA-MB-231. Helle exhibited more potent cytotoxicity than Areno in both cancer cells, and MCF-7 cells were more susceptible to both drugs in comparison with MDA-MB-231 cells. Apoptotic-like morphological characteristics, along with the downregulation of the expression level of Bcl-2 and Bcl-xL and the upregulation of the expression level of Bad, were observed in Helle-treated MCF-7 cells. Helle also caused the activation of caspase-8, caspase-9, along with the cleavage of poly(ADP-ribose) polymerase in MCF-7 cells. Helle-mediated necrosis-like phenotype, as evidenced by the increased propidium iodide (PI)-positive cells was further observed. G₂/M cell cycle arrest was also induced by Helle in the cells. Upregulation of the expression level of p21 and downregulation of the expression level of cyclin D1, cyclin E1, cdc25C and survivin were observed in MCF-7 cells treated with Helle and occurred in parallel with G₂/M arrest. Autophagy was triggered in MCF-7 cells and the addition of wortmannin or 3-MA, two well-known autophagy inhibitors, slightly but significantly rescued the cells. Furthermore, similar alterations of some key molecules associated with the aforementioned biological phenomena were observed in MDA-MB-231 cells. Intriguingly, the numbers of PI-positive cells in Helle-treated MCF-7 cells were significantly reduced by wortmannin and 3-MA, respectively. In addition, Helle-triggered G₂/M arrest was significantly corrected by wortmannin, suggesting autophagy induction contributed to Helle-induced cytotoxicity of breast cancer cells by modulating necrosis and cell cycle arrest. Collectively, our results suggested potential usefulness of both Helle and Areno in developing therapeutic strategies to treat patients with different types of breast cancer, especially ER-positive breast cancer.

• G2/M arrest
• apoptosis
• arenobufagin
• autophagy
• breast cancer cells
• hellebrigenin
• necrosis

• Antitumor agents
• Arenobufagin
• Cardiotoxicity
• Natural product

• Bufanolides/chemistry
• Bufanolides/pharmacology
• Antineoplastic Agents/chemistry
• Antineoplastic Agents/pharmacology
• Antineoplastic Agents/chemical synthesis
• Humans
• Animals
• Cell Line, Tumor
• Peptides/chemistry
• Peptides/pharmacology
• Peptides/chemical synthesis
• Cardiotoxicity/etiology
• Drug Discovery
• Structure-Activity Relationship
• Amphibian Venoms/chemistry
• Amphibian Venoms/pharmacology

Since Rhinella sp. toads produce bioactive substances, some species have been used in traditional medicine and magical practices by ancient cultures in Peru. During several decades, the Rhinella horribilis toad was confused with the invasive toad Rhinella marina, a species documented with extensive toxinological studies. In contrast, the chemical composition and biological effects of the parotoid gland secretions (PGS) remain still unknown for R. horribilis. In this work, we determine for the first time 55 compounds from the PGS of R. horribilis, which were identified using HPLC-MS/MS. The crude extract inhibited the proliferation of A549 cancer cells with IC₅₀ values of 0.031 ± 0.007 and 0.015 ± 0.001 µg/mL at 24 and 48 h of exposure, respectively. Moreover, it inhibited the clonogenic capacity, increased ROS levels, and prevented the etoposide-induced apoptosis, suggesting that the effect of R. horribilis poison secretion was by cell cycle blocking before of G2/M-phase checkpoint. Fraction B was the most active and strongly inhibited cancer cell migration. Our results indicate that the PGS of R. horribilis are composed of alkaloids, bufadienolides, and argininyl diacids derivatives, inhibiting the proliferation and migration of A549 cells.

• Peru
• Rhinella horribilis
• bufadienolides
• cell migration
• etoposide
• proliferation
• toad toxins

• Anticancer
• Apoptosis
• Autophagy
• Cardiac glycosides
• Na/K-ATPase

• Anticancer activity
• Bufadienolides
• Molecular mechanism
• Prodrug
• Tumor-targeting delivery

Hepatocellular carcinoma (HCC) remains a challenge in the medical field due to its high malignancy and mortality rates particularly for HCC, which has developed multidrug resistance. Therefore, the identification of efficient chemotherapeutic drugs for multidrug resistant HCC has become an urgent issue. Natural products have always been of significance in drug discovery. In the present study, a cell-based method was used to screen a natural compound library, which consisted of 78 compounds, and the doxorubicin-resistant cancer cell line, HepG2/ADM, as screening tools. The findings of the present study led to the shortlisting of one of the compounds, digitoxin, which displayed an inhibitory effect on HepG2/ADM cells, with 50% inhibitory concentration values of 132.65±3.83, 52.29±6.26, and 9.13±3.67 nM for 24, 48, and 72 h, respectively. Immunofluorescence, western blotting and cell cycle analyses revealed that digitoxin induced G₂/M cell cycle arrest via the serine/threonine-protein kinase ATR (ATR)-serine/threonine-protein kinase Chk2 (CHK2)-M-phase inducer phosphatase 3 (CDC25C) signaling pathway in HepG2/ADM cells, which may have resulted from a DNA double-stranded break. Digitoxin also induced mitochondrial apoptosis, which was characterized by changes in the interaction between Bcl-2 and Bax, the release of cytochrome c, as well as the activation of the caspase-3 and −9. To the best of our knowledge, the present study is the first report that digitoxin displays an anti-HCC effect on HepG2/ADM cells through G₂/M cell cycle arrest, which was mediated by the ATR-CHK2-CDC25C signaling pathway and mitochondrial apoptosis. Therefore, digitoxin could be a promising chemotherapeutic agent for the treatment of patients with HCC.

• G2/M phase arrest
• apoptosis
• digitoxin
• liver cancer
• multidrug resistance

• Anti-Tumor
• Bufadienolide
• Cardiac steroids
• Chan’Su
• Heart disease

Emerging evidence has shown that cinobufagin, as an active ingredient of Venenum Bufonis, inhibits tumor development. The aim of this study was to investigate the inhibitory effects of cinobufagin on A375 human malignant melanoma cells. MTT and colony formation assays showed that cinobufagin significantly inhibited A375 cell proliferation and cell colony formation. Additional studies demonstrated that cinobufagin markedly increased the levels of ATM serine/threonine kinase (ATM) and checkpoint kinase 2 (Chk2) and decreased the levels of cell division cycle 25C (CDC25C), cyclin-dependent kinase 1 (CDK1), and cyclin B, subsequently inducing G2/M cell cycle arrest in A375 cells. Moreover, cinobufagin clearly inhibited the levels of phosphoinositide 3-kinase (PI3K), phosphorylated PI3K (p-PI3K), AKT, p-AKT, and B-cell lymphoma 2 (Bcl-2). By contrast, it increased the levels of Bcl-2-associated death promoter, Bcl-2-associated X, cytoplasmic cytochrome C, and apoptotic protease activating factor 1, leading to increased levels of cleaved caspase-9 and cleaved caspase-3, resulting in the apoptosis of A375 cells. Together, these results indicate that cinobufagin can induce cell cycle arrest at the G2/M phase and apoptosis, leading to inhibition of A375/B16 cell proliferation. Thus, cinobufagin may be useful for melanoma treatment.

• A375 cell
• G2/M phase
• cell cycle arrest
• cinobufagin
• melanoma
• mitochondria-mediated apoptosis

• 3D-QSAR
• Bufadienolides
• Cytotoxicity
• Toad venom

• Amphibian Venoms/pharmacology
• Animals
• Antineoplastic Agents/pharmacology
• Apoptosis
• Bufanolides/pharmacology
• Cell Cycle Checkpoints
• Cell Line, Tumor
• Humans
• Molecular Structure
• Quantitative Structure-Activity Relationship

It has been demonstrated that bufadienolides exert potent anti-cancer activity in various tumor types. However, the mechanisms that underlie their anti-cancer properties remain unclear. Yes-associated protein, a key effector of Hippo signaling, functions as a transcription coactivator, plays oncogenic and tumor suppressor roles under different conditions. Here, we report that arenobufagin (ABF), a representative bufadienolide, induced breast cancer MCF-7 cells to undergo apoptosis, which occurred through the JNK-mediated multisite phosphorylation of YAP.

Cytotoxicity was examined using an MTT assay. ABF-induced apoptosis was measured with a TUNEL assay and Annexin V-FITC/PI double staining assay. Western blotting, immunofluorescence, qRT-PCR and coimmunoprecipitation were employed to assess the expression levels of the indicated molecules. Lose-of-function experiments were carried out with siRNA transfection and pharmacological inhibitors. ABF-induced phosphopeptides were enriched with Ti4⁺-IMAC chromatography and further subjected to reverse-phase nano-LC–MS/MS analysis.

ABF significantly reduced the viability of MCF-7 cells and increased the percentage of early and late apoptotic cells in a concentration- and time-dependent manner. Following ABF treatment, YAP accumulated in the nucleus and bound to p73, which enhanced the transcription of the pro-apoptotic genes Bax and p53AIP1. YAP knock-down significantly attenuated ABF-induced apoptotic cell death. Importantly, we found that the mobility shift of YAP was derived from its phosphorylation at multiple sites, including Tyr357. Moreover, mass spectrometry analysis identified 19 potential phosphorylation sites in YAP, with a distribution of 14 phosphoserine and 5 phosphothreonine residues. Furthermore, we found that the JNK inhibitor SP600125 completely diminished the mobility shift of YAP and its phosphorylation at Tyr357, the binding of YAP and p73, the transcription of Bax and p53AIP1 as well as the apoptosis induced by ABF. These data indicate that ABF induced YAP multisite phosphorylation, which was associated with p73 binding, and that apoptosis was mediated by the JNK signaling pathway.

Our data demonstrate that ABF suppresses MCF-7 breast cancer proliferation by triggering the pro-apoptotic activity of YAP, which is mediated by JNK signaling-induced YAP multisite phosphorylation as well as its association with p73. The present work not only provides additional information on the use of ABF as an anti-breast cancer drug, but also offers evidence that the induction of the tumor suppressor role of YAP may be a therapeutic strategy.

The online version of this article (10.1186/s12935-018-0706-9) contains supplementary material, which is available to authorized users.

• Apoptosis
• Arenobufagin
• Breast cancer
• Bufadienolide
• JNK
• YAP

Glioblastoma is the most common and lethal intracranial tumor type, characterized by high angiogenic and infiltrative capacities. To provide a novel insight into therapeutic strategies against glioblastoma, the cytotoxicity of arenobufagin and hellebrigenin was investigated in the human glioblastoma cell line, U-87. Similar dose-dependent cytotoxicity was observed in the cells, whereas no detectable toxicity was confirmed in mouse primary astrocytes. Treatment with each drug downregulated the expression levels of Cdc25C, Cyclin B1 and survivin, which occurred in parallel with G₂/M phase arrest. Necrotic-like cell death was only observed in the cells treated with a relatively high concentration (>100 ng/ml). These results indicate that the two drugs exhibited distinct cytotoxicity against cancerous glial cells with high potency and selectivity, suggesting that growth inhibition associated with G₂/M phase arrest and/or necrosis were attributed to their toxicities. Activation of the p38 mitogen activated protein kinase (MAPK) signaling pathway was also observed in treated cells. Notably, a specific inhibitor of p38 MAPK, SB203580, itself caused a significant decrease in cell viability, and further enhanced the cytotoxicity of the two drugs, suggesting an important pro-survival role for p38 MAPK. Given that p38 MAPK serves an essential role in promoting glioblastoma cell survival, developing a novel combination regimen of arenobufagin/hellebrigenin plus a p38 MAPK inhibitor may improve the efficacy of the two drugs, and may provide more therapeutic benefits to patients with glioblastoma. The qualitative assessment demonstrated the existence of arenobufagin in the cerebrospinal fluid of arenobufagin-treated rats, supporting its clinical application.

Hepatocellular carcinoma (HCC) is one of the most aggressive malignant tumors, of which treatment options are limited especially in advanced stage. Bufalin, the major digoxin-like component of the traditional Chinese medicine Chansu, exhibits significant antitumor activities in hepatoma cells, but the potential mechanism is obscure. Cell cycle-related kinase (CCRK) is recently identified to be a crucial oncogenic master regulator to drive hepatocarcinogenesis. Here we investigated the molecular function of bufalin on CCRK-regulated signaling pathway, and expounded the underlying mechanism in HCC suppression. In vitro with PLC5 HCC cells and human immortal LO2 cells, proliferation, malignant transformation and cell cycle progression assays were performed to evaluate the antitumor effect of bufalin. In vivo with xenograft and orthotopic mice models, tumor growths with weight and volume change were assessed with or without bufalin treatment. Western blot, RT-qPCR, immunofluorescence and immunohistochemistry were conducted to examine the expression level of CCRK and β-catenin/TCF signaling cascade. We revealed that bufalin suppresses PLC5 HCC cell proliferation, transformation and cell cycle progression rather than LO2 cells, which is correlated with CCRK-mediated β-catenin/TCF signaling. It was also confirmed in mice model. Thus, bufalin is a potential anti-HCC therapeutic candidate through the inhibition of CCRK-driven β-catenin/TCF oncogenic signaling pathway.

We previously found that the histone methyltransferase suppressor of variegation, enhancer of zeste, trithorax and myeloid-nervy-deformed epidermal autoregulatory factor-1 domain-containing protein 3 (SMYD3) is a potential independent predictive factor or prognostic factor for overall survival in gastric cancer patients, but its roles seem to differ from those in other cancers. Therefore, in this study, the detailed functions of SMYD3 in cell proliferation and migration in gastric cancer were examined.

SMYD3 was overexpressed or suppressed by transfection with an expression plasmid or siRNA, and a wound healing migration assay and Transwell assay were performed to detect the migration and invasion ability of gastric cancer cells. Additionally, an MTT assay and clonogenic assay were performed to evaluate cell proliferation, and a cell cycle analysis was performed by propidium iodide staining. Furthermore, the expression of genes implicated in the ataxia telangiectasia mutated (ATM) pathway and proteins involved in cell cycle regulation were detected by polymerase chain reaction and western blot analyses.

Compared with control cells, gastric cancer cells transfected with si-SMYD3 showed lower migration and invasion abilities (P<0.05), and the absence of SMYD3 halted cells in G2/M phase and activated the ATM pathway. Furthermore, the opposite patterns were observed when SMYD3 was elevated in normal gastric cells.

To the best of our knowledge, this study provides the first evidence that the absence of SMYD3 could inhibit the migration, invasion, and proliferation of gastric cancer cells and halt cells in G2/M phase via the ATM-CHK2/p53-Cdc25C pathway. These findings indicated that SMYD3 plays crucial roles in the proliferation, migration, and invasion of gastric cancer cells and may be a useful therapeutic target in human gastric carcinomas.

• ATM pathway
• G2 phase cell cycle checkpoints
• SMYD3 protein, human
• Stomach neoplasms

• cyclooxygenase-2
• inducible nitric oxide synthase
• isoflurane + N2O inhalation
• myocardial function
• propofol + fentanyl anesthesia

Arenobufagin, an active component isolated from the traditional Chinese medicine Chan Su, exhibits anticancer influences in several human malignancies. However, the effects and action mechanisms of arenobufagin on non-small-cell lung cancer (NSCLC) are still unknown. In this study, we reported that arenobufagin acted through activation of Noxa-related pathways and promoted apoptotic cell death in human NSCLC cells. Our results revealed that arenobufagin-induced apoptosis was caspase-dependent, as evidenced by the fact that caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP) were cleaved, and pretreatment with a pan-caspase inhibitor Z-VAD-FMK inhibited the pro-apoptosis effect of arenobufagin. Mechanistically, we further found that arenobufagin rapidly upregulated the expression of the pro-apoptosis protein Noxa, and abrogated the anti-apoptosis protein Mcl-1, a major binding partner of Noxa in the cell. More importantly, the knockdown of Noxa greatly blocked arenobufagin-induced cell death, highlighting the contribution of this protein in the anti-NSCLC effects of arenobufagin. Interestingly, arenobufagin also increased the expression of p53, a direct transcriptional activator for the upregulation of the Noxa protein. Taken together, our results suggest that arenobufagin is a potential anti-NSCLC agent that triggers apoptotic cell death in NSCLC cells through interfering with the Noxa-related pathway.

• Mcl-1
• Noxa
• arenobufagin
• non-small-cell lung cancer
• p53

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Intense efforts have been made to elucidate the pathogeny, but the molecular mechanisms of HCC are still not well understood. To identify the candidate genes in the carcinogenesis and progression of HCC, microarray datasets GSE19665, GSE33006 and GSE41804 were downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified, and function enrichment analyses were performed. The protein-protein interaction network (PPI) was constructed and the module analysis was performed using STRING and Cytoscape. A total of 273 DEGs were identified, consisting of 189 downregulated genes and 84 upregulated genes. The enriched functions and pathways of the DEGs include protein activation cascade, complement activation, carbohydrate binding, complement and coagulation cascades, mitotic cell cycle and oocyte meiosis. Sixteen hub genes were identified and biological process analysis revealed that these genes were mainly enriched in cell division, cell cycle and nuclear division. Survival analysis showed that BUB1, CDC20, KIF20A, RACGAP1 and CEP55 may be involved in the carcinogenesis, invasion or recurrence of HCC. In conclusion, DEGs and hub genes identified in the present study help us understand the molecular mechanisms underlying the carcinogenesis and progression of HCC, and provide candidate targets for diagnosis and treatment of HCC.

• 19-oxocinobufotalin (PubChem CID: 102093790)
• Arenobufagin
• Arenobufagin (PubChem CID: 12305198)
• Bufadienolides
• Bufarenogin (PubChem CID: 167607)
• Cinobufotalin (PubChem CID: 259776)
• EMT
• Metastatic prostate cancer
• β-catenin

• LY294002
• cariporide
• malignant mesothelioma
• p53
• phosphatidylinositol-3-kinase

• Apoptosis/drug effects
• Cell Cycle/drug effects
• Cell Line, Tumor
• Cell Proliferation/drug effects
• Chromones/pharmacology
• Culture Media
• DNA Damage
• Guanidines/pharmacology
• Guanidines/therapeutic use
• Humans
• Hydrogen-Ion Concentration
• Lung Neoplasms/drug therapy
• Lung Neoplasms/pathology
• Membrane Potential, Mitochondrial/drug effects
• Mesothelioma/drug therapy
• Mesothelioma/pathology
• Mesothelioma, Malignant
• Mitochondria/drug effects
• Mitochondria/metabolism
• Morpholines/pharmacology
• Phosphorylation/drug effects
• Proto-Oncogene Proteins c-akt/metabolism
• Reactive Oxygen Species/metabolism
• Sulfones/pharmacology
• Sulfones/therapeutic use
• Tumor Suppressor Protein p53/metabolism
• Up-Regulation/drug effects

Arenobufagin (ABG) is a major active component of toad venom, a traditional Chinese medicine used for cancer therapy. However, poor aqueous solubility limits its pharmacological studies in vivo due to administration difficulties. In this study, we aimed to develop a polymeric nanomicelle (PN) system to enhance the solubility of ABG for effective intravenous delivery. ABG-loaded PNs (ABG-PNs) were prepared with methoxy poly (ethylene glycol)-block-poly (d,l-lactic-co-glycolic acid) (mPEG-PLGA) using the solvent-diffusion technique. The obtained ABG-PNs were 105 nm in size with a small polydispersity index of 0.08. The entrapment efficiency and drug loading were 71.9% and 4.58%, respectively. Cellular uptake of ABG-PNs was controlled by specific clathrin-mediated endocytosis. In addition, ABG-PNs showed improved drug pharmacokinetics with an increased area under the curve value (a 1.73-fold increase) and a decreased elimination clearance (37.8% decrease). The nanomicelles showed increased drug concentrations in the liver and lung. In contrast, drug concentrations in both heart and brain were decreased. Moreover, the nanomicelles enhanced the anticancer effect of the pure drug probably via increased cellular uptake of drug molecules. In conclusion, the mPEG-PLGA-based nanomicelle system is a satisfactory carrier for the systemic delivery of ABG.

• arenobufagin
• bufanolide steroid
• mPEG-PLGA
• nanomicelles

• Antiproliferative activity
• Antiprotozoal
• Bufadienolide derivatives
• Paraguayan toads
• Rhinella ornata
• Rhinella schneideri
• Rhinella scitula

• Amphibian Venoms/chemistry
• Amphibian Venoms/isolation & purification
• Amphibian Venoms/pharmacology
• Animals
• Breast Neoplasms/pathology
• Bufo marinus
• Cell Line, Tumor
• Cell Proliferation/drug effects
• Cell Proliferation/physiology
• Cells, Cultured
• Female
• Humans
• Macrophages/drug effects
• Macrophages/physiology
• Medicine, Traditional/methods
• Mice
• Paraguay

Although the possibility of developing cardiac steroids/cardiac glycosides as novel cancer therapeutic agents has been recognized, the mechanism of their anticancer activity is still not clear enough. Toad venom extract containing bufadienolides, which belong to cardiac steroids, has actually long been used as traditional Chinese medicine in clinic for cancer therapy in China. The cytotoxicity of arenobufagin, a bufadienolide isolated from toad venom, on human cervical carcinoma HeLa cells was checked. And, the protein expression profile of control HeLa cells and HeLa cells treated with arenobufagin for 48 h was analyzed using two-dimensional electrophoresis, respectively. Differently expressed proteins in HeLa cells treated with arenobufagin were identified and the pathways related to these proteins were mapped from KEGG database. Computational molecular docking was performed to verify the binding of arenobufagin and Na, K-ATPase. The effects of arenobufagin on Na, K-ATPase activity and proteasome activity of HeLa cells were checked. The protein-protein interaction network between Na, K-ATPase and proteasome was constructed and the expression of possible intermediate proteins ataxin-1 and translationally-controlled tumor protein in HeLa cells treated with arenobufagin was then checked. Arenobufagin induced apoptosis and G2/M cell cycle arrest in HeLa cells. The cytotoxic effect of arenobufagin was associated with 25 differently expressed proteins including proteasome-related proteins, calcium ion binding-related proteins, oxidative stress-related proteins, metabolism-related enzymes and others. The results of computational molecular docking revealed that arenobufagin was bound in the cavity formed by the transmembrane alpha subunits of Na, K-ATPase, which blocked the pathway of extracellular Na⁺/K⁺ cation exchange and inhibited the function of ion exchange. Arenobufagin inhibited the activity of Na, K-ATPase and proteasome, decreased the expression of Na, K-ATPase α1 and α3 subunits and increased the expression of WEE1 in HeLa cells. Antibodies against Na, K-ATPase α1 and α3 subunits alone or combinated with arenobufagin also inhibited the activity of proteasome. Furthermore, the expression of the possible intermediate proteins ataxin-1 and translationally-controlled tumor protein was increased in HeLa cells treated with arenobufagin by flow cytometry analysis, respectively. These results indicated that arenobufagin might directly bind with Na, K-ATPase α1 and α3 subunits and the inhibitive effect of arenobufagin on proteasomal activity of HeLa cells might be related to its binding with Na, K-ATPase.