The synergistic antitumor effect of cinobufagin and cisplatin in human osteosarcoma cell line in vitro and in vivo

Combinational Antitumor Strategies Based on the Active Ingredients of Toad Skin and Toad Venom

A multidrug combination strategy is an important mean to improve the treatment of cancer and is the mainstream scheme of clinical cancer treatment. The active ingredients of traditional Chinese medicine, represented by toad skin and toad venom, have the advantages of high efficiency, low toxicity, wide action and multiple targets and have become ideal targets in combined treatment strategies for tumors in recent years. Toad skin and toad venom are traditional Chinese animal medicines derived from Bufo bufo gargarizans Cantor or Bufo melanostictus Schneider that have shown excellent therapeutic effects on the treatment of various cancers and cancer pain as adjuvant antitumor drugs in clinical practice. The involved mechanisms include inducing apoptosis, arresting the cell cycle, inhibiting cell proliferation, migration and invasion, inhibiting tumor angiogenesis, reversing the multidrug resistance of tumor cells, and regulating multiple signaling pathways and targets. Moreover, a multidrug combination strategy based on a nanodelivery system can realize the precise loading of the active ingredients of toad skin or toad venom and other antitumor drugs and carry drugs to overcome physiological and pathological barriers, complete efficient enrichment in tumor tissues, and achieve targeted delivery to tumor cells and the controlled release of drugs, thus enhancing antitumor efficacy and reducing toxicity and side effects. This article reviewed the clinical efficacy and safety of the combination of toad skin and toad venom with chemotherapeutic drugs, targeted drugs, analgesics and other drugs; evaluated the effects and mechanisms of the combination of toad skin and toad venom with chemotherapy, targeted therapy, radiotherapy or hyperthermia, traditional Chinese medicine, signaling pathway inhibitors and other therapies in cell and animal models; and summarized the codelivery strategies for the active ingredients of toad skin and toad venom with chemotherapeutic drugs, small-molecule targeted drugs, monoclonal antibodies, active ingredients of traditional Chinese medicine, and photodynamic and photothermal therapeutic drugs to provide a basis for the rational drug use of toad skin and toad venom in the clinic and the development of novel drug delivery systems.

Chemical Composition, Pharmacological Effects and Clinical Applications of Cinobufacini

Chinese medicine cinobufacini is an extract from the dried skin of Bufo bufo gargarizans Cantor, with active ingredients of bufadienolides and indole alkaloids. With further research and clinical applications, it is found that cinobufacini alone or in combination with other therapeutic methods can play an anti-tumor role by controlling proliferation of tumor cells, promoting apoptosis, inhibiting formation of tumor neovascularization, reversing multidrug resistance, and regulating immune response; it also has the functions of relieving cancer pain and regulating immune function. In this paper, the chemical composition, pharmacological effects, clinical applications, and adverse reactions of cinobufacini are summarized. However, the extraction of monomer components of cinobufacini, the relationship between different mechanisms, and the causes of adverse reactions need to be further studied. Also, high-quality clinical studies should be conducted.

Global trends in bufalin application research for cancer from 2003 to 2022: A bibliometric and visualised analysis

Background

Bufalin, the main active ingredient of the traditional Chinese medicine huachansu, is used in the clinical treatment of colorectal cancer and has multiple effects, including the inhibition of migratory invasion, reversal of multi-drug resistance, induction of apoptosis and differentiation, and inhibition of angiogenesis.

Methods

We collected relevant articles on bufalin from 2003 to 2022 using the Web Science platform, and analysed the information using VOSviewer, CiteSpace, and Microsoft Excel to categorise and summarise the publications over the past 20 years.

Results

We collected 371 papers, with a steady increase in the number of articles published globally. China has the highest number of published articles, whereas Japan has the highest number of citations. Currently, there is considerable enthusiasm for investigating the anti-tumour mechanism of bufalin and optimising drug delivery systems for its administration.

Conclusion

For the first time, we present a comprehensive overview of papers published worldwide on bufalin over the past two decades and the progress of its application in tumour therapy. We summarised the key authors, institutions, and countries that have contributed to the field and the potential of bufalin for the treatment of cancer. This will help other researchers obtain an overview of progress in the field, enhance collaboration and knowledge sharing, and promote future research on bufalin.

Mechanisms underlying the therapeutic effects of cinobufagin in treating melanoma based on network pharmacology, single-cell RNA sequencing data, molecular docking, and molecular dynamics simulation

Malignant melanoma is one of the most aggressive of cancers; if not treated early, it can metastasize rapidly. Therefore, drug therapy plays an important role in the treatment of melanoma. Cinobufagin, an active ingredient derived from Venenum bufonis, can inhibit the growth and development of melanoma. However, the mechanism underlying its therapeutic effects is unclear. The purpose of this study was to predict the potential targets of cinobufagin in melanoma. We gathered known and predicted targets for cinobufagin from four online databases. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were then performed. Gene expression data were downloaded from the GSE46517 dataset, and differential gene expression analysis and weighted gene correlation network analysis were performed to identify melanoma-related genes. Using input melanoma-related genes and drug targets in the STRING online database and applying molecular complex detection (MCODE) analysis, we identified key targets that may be the potential targets of cinobufagin in melanoma. Moreover, we assessed the distribution of the pharmacological targets of cinobufagin in melanoma key clusters using single-cell data from the GSE215120 dataset obtained from the Gene Expression Omnibus database. The crucial targets of cinobufagin in melanoma were identified from the intersection of key clusters with melanoma-related genes and drug targets. Receiver operating characteristic curve (ROC) analysis, survival analysis, molecular docking, and molecular dynamics simulation were performed to gain further insights. Our findings suggest that cinobufagin may affect melanoma by arresting the cell cycle by inhibiting three protein tyrosine/serine kinases (EGFR, ERBB2, and CDK2). However, our conclusions are not supported by relevant experimental data and require further study.

Cinobufagin: a promising therapeutic agent for cancer

OBJECTIVES

Cinobufagin is a natural active ingredient isolated from the traditional Chinese medicine Venenum Bufonis (Chinese: Chansu), which is the dried secretion of the postauricular gland or skin gland of the Bufo gargarizans Cantor or Bufo melanostictus Schneider. There is increasing evidence indicating that cinobufagin plays an important role in the treatment of cancer. This article is to review and discuss the antitumor pharmacological effects and mechanisms of cinobufagin, along with a description of its toxicity and pharmacokinetics.

METHODS

The public databases including PubMed, China National Knowledge Infrastructure and Elsevier were referenced, and 'cinobufagin', 'Chansu', 'Venenum Bufonis', 'anticancer', 'cancer', 'carcinoma', and 'apoptosis' were used as keywords to summarize the comprehensive research and applications of cinobufagin published up to date.

KEY FINDINGS

Cinobufagin can induce tumour cell apoptosis and cycle arrest, inhibit tumour cell proliferation, migration, invasion and autophagy, reduce angiogenesis and reverse tumour cell multidrug resistance, through triggering DNA damage and activating the mitochondrial pathway and the death receptor pathway.

CONCLUSIONS

Cinobufagin has the potential to be further developed as a new drug against cancer.

Targeting signaling pathways in osteosarcoma: Mechanisms and clinical studies

Osteosarcoma (OS) is a highly prevalent bone malignancy among adolescents, accounting for 40% of all primary malignant bone tumors. Neoadjuvant chemotherapy combined with limb-preserving surgery has effectively reduced patient disability and mortality, but pulmonary metastases and OS cells' resistance to chemotherapeutic agents are pressing challenges in the clinical management of OS. There has been an urgent need to identify new biomarkers for OS to develop specific targeted therapies. Recently, the continued advancements in genomic analysis have contributed to the identification of clinically significant molecular biomarkers for diagnosing OS, acting as therapeutic targets, and predicting prognosis. Additionally, the contemporary molecular classifications have revealed that the signaling pathways, including Wnt/β-catenin, PI3K/AKT/mTOR, JAK/STAT3, Hippo, Notch, PD-1/PD-L1, MAPK, and NF-κB, have an integral role in OS onset, progression, metastasis, and treatment response. These molecular classifications and biological markers have created new avenues for more accurate OS diagnosis and relevant treatment. We herein present a review of the recent findings for the modulatory role of signaling pathways as possible biological markers and treatment targets for OS. This review also discusses current OS therapeutic approaches, including signaling pathway-based therapies developed over the past decade. Additionally, the review covers the signaling targets involved in the curative effects of traditional Chinese medicines in the context of expression regulation of relevant genes and proteins through the signaling pathways to inhibit OS cell growth. These findings are expected to provide directions for integrating genomic, molecular, and clinical profiles to enhance OS diagnosis and treatment.

Cinobufagin inhibits proliferation of acute myeloid leukaemia cells by repressing c-Myc pathway-associated genes

Cinobufagin is a cardiotoxic bufanolide steroid secreted by the Asiatic toad, Bufo gargarizans. Bufanolides inhibit Na⁺/K⁺ ATPase and have similar effects as cardiac glycosides, such as digitoxin or ouabain derived from toxic herbs. Recently, the anti-cancer effects of bufanolides have gained attention, however the underlying molecular mechanisms remain unclear. Selecting cinobufagin as a candidate anti-leukaemia agent, we here conducted transcriptomic analyses on the effect of cinobufagin on human acute myeloid leukaemia (AML) cell lines, HL60 and Kasumi-1. Flow cytometry analysis showed that cinobufagin induced apoptosis in both cell lines. RNA-sequencing (RNA-seq) of the two cell lines treated with cinobufagin revealed commonly downregulated genes with enrichment in the term "Myc active pathway" according to Gene Ontology (GO) analysis. Gene Set Enrichment Analysis (GSEA) of genes downregulated by cinobufagin also showed "MYC_TARGETS_V2" with the highest normalised enrichment score (NES) in both cell lines. In contrast, hallmarks such as "TNFA_SIGNALING_VIA_NFKB", "APOPTOSIS", and "TGF_BETA_SIGNALING" were significantly enriched as upregulated gene sets. Epigenetic analysis using chromatin immunoprecipitation and sequencing (ChIP-seq) confirmed that genes encoding cell death-related signalling molecules were upregulated by gain of H3K27ac, whereas downregulation of c-Myc-related genes was not accompanied by H3K27ac alteration. Cinobufagin is an anti-proliferative natural compound with c-Myc-inhibiting and epigenetic-modulating activity in acute myeloid leukaemia.

Network Pharmacology Prediction: The Possible Mechanisms of Cinobufotalin against Osteosarcoma

OBJECTIVE

To explore the active compounds and targets of cinobufotalin (huachansu) compared with the osteosarcoma genes to obtain the potential therapeutic targets and pharmacological mechanisms of action of cinobufotalin on osteosarcoma through network pharmacology.

METHODS

The composition of cinobufotalin was searched by literature retrieval, and the target was selected from the CTD and TCMSP databases. The osteosarcoma genes, found from the GeneCards, OMIM, and other databases, were compared with the cinobufotalin targets to obtain potential therapeutic targets. The protein-protein interaction (PPI) network of potential therapeutic targets, constructed through the STRING database, was inputted into Cytoscape software to calculate the hub genes, using the NetworkAnalyzer. The hub genes were inputted into the Kaplan-Meier Plotter online database for exploring the survival curve. Functional enrichment analysis was identified using the DAVID database.

RESULTS

28 main active compounds of cinobufotalin were explored, including bufalin, adenosine, oleic acid, and cinobufagin. 128 potential therapeutic targets on osteosarcoma are confirmed among 184 therapeutic targets form cinobufotalin. The hub genes included TP53, ACTB, AKT1, MYC, CASP3, JUN, TNF, VEGFA, HSP90AA1, and STAT3. Among the hub genes, TP53, ACTB, MYC, TNF, VEGFA, and STAT3 affect the patient survival prognosis of sarcoma. Through function enrichment analysis, it is found that the main mechanisms of cinobufotalin on osteosarcoma include promoting sarcoma apoptosis, regulating the cell cycle, and inhibiting proliferation and differentiation.

CONCLUSION

The possible mechanisms of cinobufotalin against osteosarcoma are preliminarily predicted through network pharmacology, and further experiments are needed to prove these predictions.

Practical strategy to construct anti-osteosarcoma bone substitutes by loading cisplatin into 3D-printed titanium alloy implants using a thermosensitive hydrogel

Surgical resection and perioperative adjuvant chemotherapy-based therapies have improved the prognosis of patients with osteosarcoma; however, intraoperative bone defects, local tumour recurrence, and chemotherapy-induced adverse effects still affect the quality of life of patients. Emerging 3D-printed titanium alloy (Ti₆Al₄V) implants have advantages over traditional implants in bone repair, including lower elastic modulus, lower stiffness, better bone conduction, more bone in-growth, stronger mechanical interlocking, and lager drug-loading capacity by their inherent porous structure. Here, cisplatin, a clinical first-line anti-osteosarcoma drug, was loaded into Ti₆Al₄V implants, within a PLGA-PEG-PLGA thermo-sensitive hydrogel, to construct bone substitutes with both anti-osteosarcoma and bone-repair functions. The optimal concentrations of cisplatin (0.8 and 1.6 mg/mL) were first determined in vitro. Thereafter, the anti-tumour effect and biosafety of the cisplatin/hydrogel-loaded implants, as well as their bone-repair potential were evaluated in vivo in tumour-bearing mouse, and bone defect rabbit models, respectively. The loading of cisplatin reduced tumour volume by more than two-thirds (from 641.1 to 201.4 mm³) with negligible organ damage, achieving better anti-tumour effects while avoiding the adverse effects of systemic cisplatin delivery. Although bone repair was hindered by cisplatin loading at 4 weeks, no difference was observed at 8 weeks in the context of implants with versus without cisplatin, indicating acceptable long-term stability of all implants (with 8.48%–10.04% bone in-growth and 16.94%–20.53% osseointegration). Overall, cisplatin/hydrogel-loaded 3D-printed Ti₆Al₄V implants are safe and effective for treating osteosarcoma-caused bone defects, and should be considered for clinical use.

•

Vehiculated within PLGA-PEG-PLGA hydrogel, cisplatin can be conveniently loaded into 3D-printed Ti₆Al₄V implants.

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The cisplatin/hydrogel-loaded implants are safe and show a good anti-tumour potential both in vitro and in vivo.

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This strategy has better anti-osteosarcoma effects and fewer side effects than the conventional cisplatin delivery method.

•

Cisplatin loading does not decrease the bone repair effect of 3D-printed Ti₆Al₄V implants 8 weeks after surgery.

•

As the components of the implants are non-toxic, this strategy has great potential for clinical translation.

Targeting Notch in oncology: the path forward

Notch signalling is involved in many aspects of cancer biology, including angiogenesis, tumour immunity and the maintenance of cancer stem-like cells. In addition, Notch can function as an oncogene and a tumour suppressor in different cancers and in different cell populations within the same tumour. Despite promising preclinical results and early-phase clinical trials, the goal of developing safe, effective, tumour-selective Notch-targeting agents for clinical use remains elusive. However, our continually improving understanding of Notch signalling in specific cancers, individual cancer cases and different cell populations, as well as crosstalk between pathways, is aiding the discovery and development of novel investigational Notch-targeted therapeutics.

Molecular mechanisms of bufadienolides and their novel strategies for cancer treatment

Bufadienolides are cardioactive C24 steroids with an α-pyrone ring at position C17. In the last ten years, accumulating studies have revealed the anticancer activities of bufadienolides and their underlying mechanisms, such as induction of autophagy and apoptosis, cell cycle disruption, inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and stemness, and multidrug resistance reversal. As Na⁺/K⁺-ATPase inhibitors, bufadienolides have inevitable cardiotoxicity. Short half-lives, poor stability, low plasma concentration and oral bioavailability in vivo are obstacles for their applications as drugs. To improve the drug potency of bufadienolides and reduce their side effects, prodrug strategies and drug delivery systems such as liposomes and nanoparticles have been applied. Therefore, systematic and recapitulated information about the antitumor activity of bufadienolides, with special emphasis on the molecular or cellular mechanisms, prodrug strategies and drug delivery systems, is of high interest. Here, we systematically review the anticancer effects of bufadienolides and the molecular or cellular mechanisms of action. Research advancements regarding bufadienolide prodrugs and their tumor-targeting delivery strategies are critically summarized. This work highlights recent scientific advances regarding bufadienolides as effective anticancer agents from 2011 to 2019, which will help researchers to understand the molecular pathways involving bufadienolides, resulting in a selective and safe new lead compound or therapeutic strategy with improved therapeutic applications of bufadienolides for cancer therapy.

Cucurbitacin B and cisplatin induce the cell death pathways in MB49 mouse bladder cancer model

IMPACT STATEMENT

Alternative agents that will increase the effectiveness of cisplatin, which are widely used in the advanced stage and metastatic bladder cancer, are being investigated. In previous studies, Cucurbitacin B (CuB), which is a natural compound from the Cucurbitaceae family has been shown to inhibit the proliferation of tumor cells and create synergistic effects with cisplatin. In this study, we investigated the synergistic effect of CuB with cisplatin for the first time in bladder cancer in vitro and in vivo models. Our findings showed that CuB treatment with cisplatin reduced cell proliferation, and reduced tumor development through activating apoptosis and autophagy via PI3K/AKT/mTOR signaling pathway. Our results showed that CuB may be a new agent that can support conventional treatment in bladder cancer. Our study is important in terms of enlightening new pathways and developing new treatment methods in the treatment of bladder cancer.

The spinal microglial IL-10/β-endorphin pathway accounts for cinobufagin-induced mechanical antiallodynia in bone cancer pain following activation of α7-nicotinic acetylcholine receptors

Background

Cinobufagin is the major bufadienolide of Bufonis venenum (Chansu), which has been traditionally used for the treatment of chronic pain especially cancer pain. The current study aimed to evaluate its antinociceptive effects in bone cancer pain and explore the underlying mechanisms.

Methods

Rat bone cancer model was used in this study. The withdrawal threshold evoked by stimulation of the hindpaw was determined using a 2290 CE electrical von Frey hair. The β-endorphin and IL-10 levels were measured in the spinal cord and cultured primary microglia, astrocytes, and neurons.

Results

Cinobufagin, given intrathecally, dose-dependently attenuated mechanical allodynia in bone cancer pain rats, with the projected E_max of 90% MPE and ED₅₀ of 6.4 μg. Intrathecal cinobufagin also stimulated the gene and protein expression of IL-10 and β-endorphin (but not dynorphin A) in the spinal cords of bone cancer pain rats. In addition, treatment with cinobufagin in cultured primary spinal microglia but not astrocytes or neurons stimulated the mRNA and protein expression of IL-10 and β-endorphin, which was prevented by the pretreatment with the IL-10 antibody but not β-endorphin antiserum. Furthermore, spinal cinobufagin-induced mechanical antiallodynia was inhibited by the pretreatment with intrathecal injection of the microglial inhibitor minocycline, IL-10 antibody, β-endorphin antiserum and specific μ-opioid receptor antagonist CTAP. Lastly, cinobufagin- and the specific α-7 nicotinic acetylcholine receptor (α7-nAChR) agonist PHA-543613-induced microglial gene expression of IL-10/β-endorphin and mechanical antiallodynia in bone cancer pain were blocked by the pretreatment with the specific α7-nAChR antagonist methyllycaconitine.

Conclusions

Our results illustrate that cinobufagin produces mechanical antiallodynia in bone cancer pain through spinal microglial expression of IL-10 and subsequent β-endorphin following activation of α7-nAChRs. Our results also highlight the broad significance of the recently uncovered spinal microglial IL-10/β-endorphin pathway in antinociception.

Cinobufagin induces cell cycle arrest at the S phase and promotes apoptosis in nasopharyngeal carcinoma cells

Emerging evidence suggests that cinobufagin, an active ingredient in Venenum Bufonis, inhibits cell proliferation in several tumor cells. However, the anti-tumor effect of cinobufagin on nasopharyngeal carcinoma and the underlying molecular mechanisms are still unclear. In this study, we found that cinobufagin significantly inhibits the proliferation of nasopharyngeal carcinoma HK-1 cells. Further analyses demonstrated that cinobufagin induces cell cycle arrest at the S phase in HK-1 cells through downregulating the levels of CDK2 and cyclin E. Moreover, cinobufagin significantly downregulates the protein level of Bcl-2 and upregulates the levels of Bax, subsequently increasing the levels of cytoplasmic cytochrome c, Apaf-1, cleaved PARP1, cleaved caspase-3, and cleaved caspase-9, leading to HK-1 apoptosis. Furthermore, we found that cinobufagin significantly increases ROS levels and decreases the mitochondrial membrane potential in HK-1 cells. Collectively, these data imply that cinobufagin induces cell cycle arrest at the S phase and induces apoptosis through increasing ROS levels, thereby inhibiting cell proliferation in HK-1 cells. Therefore, cinobufagin is a promising bioactive agent that may contribute to the development of treatment strategies of nasopharyngeal carcinoma.

Cinobufagin Induces Cell Cycle Arrest at the G2/M Phase and Promotes Apoptosis in Malignant Melanoma Cells

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.

Near-infrared fluorescent carbon dots encapsulated liposomes as multifunctional nano-carrier and tracer of the anticancer agent cinobufagin in vivo and in vitro

Integrating the optical properties of near-infrared fluorescent carbon dots into liposomes may construct a multifunctional nano-system with the potential as a drug carrier, tracer and efficacy intensifier of the anticancer agent. In this study, the liposomes loaded with hydrophilic near-infrared carbon dots as a nano-carrier and tracer of lipophilic anticancer agent cinobufagin were developed. Prepared liposomes were characterized by particle size, morphology and entrapment efficiency. The drug release behavior, the tracer function, the anticancer effect and the side effect were investigated in vitro and in vivo. It was observed that the photoluminescence emission of carbon dots could be strongly enhanced up to 5 times by nano-liposomes. Due to this property, the bio-imaging of CDs + CB liposomes in vitro and in vivo could be clearly obtained. Our results also showed that the CDs + CB liposomes could be uptaken by cells (the lysosomes targeted) and delivered to the tumor site, and undoubtedly, the CDs + CB liposomes demonstrated sustained drug release, enhanced anticancer efficacy and low side effects in vivo. With the assistance of imaging function of CDs, the CDs + CB liposomes can easily display the distribution of drugs, which is very helpful for drug development and may open a novel avenue for drug delivery.