Anticancer and Antiviral Properties of Cardiac Glycosides: A Review to Explore the Mechanism of Actions

Network pharmacology analysis of Lanatoside C: molecular targets and mechanisms in the treatment of ulcerative colitis

Introduction

Ulcerative colitis (UC) is a chronic and progressive inflammatory disease of the intestines, marked by recurrent inflammation along the digestive tract, leading to symptoms such as bloody diarrhea and weight loss, severely impacting patients' quality of life. Despite extensive research, current therapeutic treatment for UC still faces challenges in long-term efficacy and safety. Lanatoside C (LanC), as a type of cardiac glycosides, has shown promising anti-inflammatory effects. This study employs network pharmacology to investigate the effects and mechanisms of LanC in the treatment of UC.

Method

LanC- and UC-associated target genes datasets were retrieved from the Genecards, DisGeNET, and Gene Expression Omnibus database. Integration analysis identified a common set of potential LanC targets for UC treatment. Analyses of Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed on these target genes. Additionally, a protein-protein interaction (PPI) network was constructed to identify the top targets with the highest connectivity. Molecular docking and cellular experiments were subsequently carried out to further validated these findings.

Results

23 intersecting genes were identified as potential targets of LanC in UC. Among these, KDR, STAT3, ABCB1, CYP3A5, and CYP2B6 emerged as the top 5 targets with high therapeutic potential. Pathway analysis indicated the involvement of fatty acid and lipid metabolism, as well as xenobiotic metabolism pathways, which could be crucial for LanC's efficacy in treating UC. Molecular docking simulations revealed favorable binding interaction between LanC and KDR, STAT3, ABCB1, CYP3A5, and CYP2B6. Furthermore, In vitro experiments demonstrated that LanC significantly inhibits LPS-induced pro-inflammatory cytokines expression in RAW264.7 cells.

Conclusion

This study demonstrates a comprehensive overview of the therapeutic potential of LanC in UC and elucidates its mechanisms of action. These findings offer a theoretical basis for further optimizing UC clinical therapy and underscore the potential of LanC as a novel therapeutic option for UC.

Evaluation of the neuroprotective potential of benzylidene digoxin 15 against oxidative stress in a neuroinflammation models induced by lipopolysaccharide and on neuronal differentiation of hippocampal neural precursor cells

Neuroinflammation, often driven by the overproduction of reactive oxygen species (ROS), plays a crucial role in the pathogenesis of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The susceptibility of the brain to oxidative stress is attributed to its high metabolic activity and limited antioxidant defense. This study aimed to evaluate the neuroprotective potential of Benzylidene Digoxin 15 (BD-15) following treatment and pretreatment in a lipopolysaccharide (LPS)-induced neuroinflammation model. Additionally, we examined whether BD-15 enhances the generation of neurons from neural progenitor cells (NPCs).Male Wistar rats were used for acute treatment studies and divided into four groups: control (saline), BD-15 (100 μg/kg), LPS (250 μg/kg), and LPS + BD-15 (250 μg/kg + 100 μg/kg). Swiss albino mice were used for chronic pretreatment studies and divided into the following groups: control (saline), BD-15 (0.56 mg/kg), LPS (1 mg/kg), and LPS + BD-15 (1 mg/kg + 0.56 mg/kg). Behavioral changes were assessed using the open field test, and brain tissues were analyzed for oxidative stress markers, including malondialdehyde (MDA), reduced glutathione (GSH), protein carbonylation, catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST). To assess neurogenesis, primary NPC cultures derived from the hippocampus of newborn Wistar rats were used, which led to reduced locomotor activity and increased oxidative stress, particularly in the cortex, as indicated by elevated MDA levels and reduced GSH levels. BD-15 treatment reversed these effects, notably by restoring GSH levels and reducing protein carbonylation in the cerebellum. Chronic BD-15 treatment in Swiss mice improved oxidative stress markers including MDA, SOD, CAT, and GST. Furthermore, BD-15 exhibits neuroprotective properties by alleviating oxidative stress and motor dysfunction, suggesting its potential as a therapeutic agent for neuroinflammatory disorders. However, BD-15 did not affect NPC cell proliferation, indicating that this cardiotonic steroid did not alter the cell cycle of these progenitor cells.

Interspecies Differences in Cytomegalovirus Inhibition by Cardiac Glycosides-A Unique Role of the Alpha3 Isoform of the Na+/K+-ATPase Pump

Cardiac glycosides (CGs), historically used to treat heart failure and arrhythmias, bind to the α subunit of the Na+/K+-ATPase pump and inhibit its activity. Their anticancer and antiviral activities are of interest. The α subunit of the Na+/K+-ATPase pump has four isoforms (α1-4), each with unique tissue distribution and expression pattern; their contributions to antiviral activities have not been studied. We previously reported that CGs inhibit human CMV (HCMV) in vitro but not mouse CMV (MCMV). In addition to the low affinity of mouse α1 for CGs, we hypothesized that other isoforms contribute to the anti-CMV activities of CGs. We show here that infection with HCMV significantly induced α3 in human foreskin fibroblasts, while MCMV did not induce mouse α3. Infection with guinea pig CMV (GPCMV) in GP fibroblasts also induced α3, and CGs inhibited GPCMV replication. HCMV inhibition with digitoxin reduced α3 expression. The concentration-dependent inhibition of HCMV with digitoxin analogs also correlated with α3 expression. Intriguingly, α3 was localized to the nucleus, and changes in its expression during infection and digitoxin treatment were mostly limited to the nucleus. At 4 h post-infection, α3 colocalized with immediate early 1 (IE1) and the promyelocytic leukemia protein (PML). An interaction of α3-PML-IE1 at 24 h post-infection was disrupted by digitoxin. The mRNA levels of IE1, major immediate early promoter (MIEP)-derived IE, and antiviral cytokines were reduced in infected digitoxin-treated cells. Summarized, these findings suggest a new role for α3 in the anti-HCMV activities of CGs via nuclear antiviral signaling pathways.

Effects of Steroidal Compounds on Viruses

Viral infections are ubiquitous, and their prevention and treatment have become a great challenge. Steroids have different biological activities, including antiviral activity, which is related to steroid structural diversity. With the intensive study of steroids, it has been found that steroids can interfere with almost any step of the viral life cycle to exert antiviral activity. In this article, we review the antiviral activity and mechanism of action of steroids and their derivatives against a range of human viruses and conclude that natural steroids and their derivatives are very promising antiviral drug candidates that deserve further study to elucidate their pharmacological potential.

Self-assembly of multi-arm star PEG containing TXA9 into nanoparticle for the efficient chemotherapy of NSCLC

TXA9, a cardiac glycoside isolated from the root of Streptocaulon juventas (Lour.) Merr., with better therapeutic effect in vitro on non-small cell lung cancer (NSCLC) than cisplatin and has no toxic side effects on the body. However, poor water solubility and rapid metabolism limited its clinical application. Multi-arm star PEG have many advantages over linear PEG, such as high drug loading due to more terminals and better anti-hemodilution ability, which have become popular carriers for drug delivery. In this study, to improve the efficacy of TXA9, 6/8armPEGn-Glycine Carbamate (Gly) (n = 10, 20, and 40 kDa) were used as carriers to prepare star PEG-TXA9 conjugates. The particle size and zeta potential of six prodrug NPs for effective tumor targeting, with suitable drug loading, and good water solubility. Compared with free TXA9, 6/8APGn-T NPs had more significant anti-tumor effects in vitro. Since the multi-arm star PEG formed an "umbrella" structure on the surface of NPs, the 8APG40k-T NPs with the best pharmacokinetic properties increased half-life of TXA9 about 60 times in vivo. In addition, the arm numbers and molecular weight of multi-arm star PEGs significantly influenced the in vivo destiny of prodrugs. In vivo experiments showed that the same dose of 8APG40k-T NPs increased the tumor inhibition rate about 3.56 or 1.22 times compared with TXA9 or cisplatin, and had good biocompatibility. This study provides a simple but effective strategy to solve the challenges caused by the poor water solubility and short half-life of TXA9 for developing the TXA9 as a safe and effective drug against NSCLC.

Pharmacological Properties of Platycarpha glomerata Extracts-A Plant Used to Treat and Manage Elephantiasis

Platycarpha glomerata (Thunb.) Less. has recently become a plant species of interest to researchers due to its biological activities and less toxic effects. Therefore, the aim of the study is to evaluate the in vitro anticancer potential and phytochemical constituents of P. glomerata plant extracts. Phytochemical screening and FTIR were carried out using standard methods. The antioxidant activity was accessed by determining its ability to scavenge the DPPH radical and nitric oxide radical, whereas the anticancer activity against prostate (DU-145 and PC-3), human T-lymphocyte (SKU-T), gastric adenocarcinoma (AGS), and human prostatic epithelial (PNTA1) cell line was evaluated using the MTT assay. The phytochemical analysis revealed the presence of tannins, flavonoids, saponins, steroids, terpenoids, and cardiac glycosides. The FTIR spectrum for the aqueous extract displayed characteristic peaks for O-H, C=O, C=C, and =C-H stretch. The aqueous ethanol and methanol extracts showed significant dose-dependent DPPH radical scavenging capacity. The aqueous, ethanol, and methanol extracts showed minimum NO scavenging activity of 4.3%, 9.6%, and 11.7% at 2500 µg/mL. The water extract demonstrated good activity against S. aureus, E. coli, and B. pumilus with an MIC of 0.195 mg/mL. The ethanol and methanol extracts significantly reduced the percentage proliferation of DU-145, PC-3, and SKU-T cells at 100 μg/mL. These extracts demonstrated strong dose-dependent DPPH and NO scavenging and antibacterial and cell proliferation inhibition activities. The strong bioactivity of P. glomerata makes it a good candidate for the isolation and identification of active compounds for anticancer and related illnesses.

The modulation of immune cell death in connection to microRNAs and natural products

Immunogenic cell death (ICD) spatiotemporally regulates damage-associated molecular patterns (DAMPs) derived from dying cancer cells to signal the immune response. Intriguingly, these DAMPs and cytokines also induce cellular responses in non-immune cells, particularly cancer cells. Several ICD-modulating natural products and miRNAs have been reported to regulate the DAMP, cytokine, and cell death responses, but they lack systemic organization and connection. This review summarizes the impacts of natural products and miRNAs on the DAMP and cytokine responses and cancer cell death responses (apoptosis, autophagy, ferroptosis, necroptosis, and pyroptosis). We establish the rationale that ICD inducers of natural products have modulating effects on miRNAs, targeting DAMPs and cytokines for immune and cancer cell death responses. In conclusion, DAMP, cytokine, and cell death responses are intricately linked in cancer cells, and they are influenced by ICD-modulating natural products and miRNAs.

Digoxin and its Na+/K+-ATPase-targeted actions on cardiovascular diseases and cancer

Na+/K+-ATPase (NKA) is a plasma membrane ion-transporting protein involved in the generation and maintenance of Na+ and K+ gradients across the cell membrane, which can produce a driving force for the secondary transport of metabolic substrates. NKA also regulates intracellular calcium that is responsible for modulating numerous cellular processes, while it interacts with many other proteins and functions as a signal transducer, with several signaling pathways being involved. Thus, NKA has become an important target for the treatment of human diseases. Cardiac glycosides are well-known NKA inhibitors, of which (+)-digoxin or digoxin has been long used for the treatment of congestive heart failure. Also, digoxin has exhibited potential antitumor activity, by targeting directly HIF-1α, NKA, and NF-κB. Thus, the function of NKA in human cardiovascular diseases and cancer and the therapeutic effects of digoxin on these diseases are summarized in the present review, with the correlations among digoxin, NKA, cardiovascular diseases, and cancer being discussed. Presented herein are also the antitumor potential of monosaccharide cardiac glycoside analogues of digoxin, including (-)-cryptanoside A, (-)-oleandrin, (-)-ouabain, and (+)-strebloside. It is hoped that this contribution will provide some helpful information for the design and discovery of new cardiac glycoside-type therapeutic agents for the treatment of cardiovascular diseases and cancer.

Preclinical 3D model screening reveals digoxin as an effective therapy for a rare and aggressive type of endometrial cancer

OBJECTIVE

Dedifferentiated endometrial carcinoma (DDEC) characterized by SWItch/Sucrose Non-Fermentable (SWI/SNF) complex inactivation is a highly aggressive type of endometrial cancer without effective systemic therapy options. Its uncommon nature and aggressive disease trajectory pose significant challenges for therapeutic progress. To address this obstacle, we focused on developing preclinical models tailored to this tumor type and established patient tumor-derived three-dimensional (3D) spheroid models of DDEC.

METHODS

High-throughput drug repurposing screens were performed on in vitro 3D spheroid models of DDEC cell lines (SMARCA4-inactivated DDEC-1 and ARID1A/ARID1B co-inactivated DDEC-2). The dose-response relationships of the identified candidate drugs were evaluated in vitro, followed by in vivo evaluation using xenograft models of DDEC-1 and DDEC-2.

RESULTS

Drug screen in 3D models identified multiple cardiac glycosides including digoxin and digitoxin as candidate drugs in both DDEC-1 and DDEC-2. Subsequent in vitro dose-response analyses confirmed the inhibitory activity of digoxin and digitoxin with both drugs showing lower IC50 in DDEC cells compared to non-DDEC endometrial cancer cells. In in vivo xenograft models, digoxin significantly suppressed the growth of DDEC tumors at clinically relevant serum concentrations.

CONCLUSION

Using biologically precise preclinical models of DDEC derived from patient tumor samples, our study identified digoxin as an effective drug in suppressing DDEC tumor growth. These findings provide compelling preclinical evidence for the use of digoxin as systemic therapy for SWI/SNF-inactivated DDEC, which may also be applicable to other SWI/SNF-inactivated tumor types.

Cardiac glycosides with cytotoxic activity from the seeds of Thevetia peruviana

Phytochemical investigation on the extract of the seeds of Thevetia peruviana resulted in the isolation of six new cardiac glycosides, namely theveperosides A-F (1-6), including a rare 19-nor-cardenolide (1), together with seven known analogues (7-13). The chemical structures of these compounds were determined based on detailed spectroscopic analysis. The cytotoxic activities of 1-13 were evaluated against MCF-7, HCT-116, HeLa, and HepG2 cancer cell lines, and their structure-activity relationships (SARs) were investigated. Compound 3 exhibited the significant cytotoxic effects with IC50 values ranging from 0.032 to 0.055 μΜ, which could induce HepG2 cells apoptosis in a dose-dependent manner.

Unveiling the Intricacies of Monoamine Oxidase-A (MAO-A) Inhibition in Colorectal Cancer: Computational Systems Biology, Expression Patterns, and the Anticancer Therapeutic Potential

Colorectal cancer (CRC) remains a significant health burden globally, necessitating a deeper understanding of its molecular intricacies for effective therapeutic interventions. Elevated monoamine oxidase-A (MAO-A) expression has been consistently observed in CRC tissues, correlating with advanced disease stages and a poorer prognosis. This research explores the systems biology effects of MAO-A inhibition with small molecule inhibitor clorgyline regarding CRC. The applied systems biology approach starts with a chemocentric informatics approach to derive high-confidence hypotheses regarding the antiproliferative effects of MAO-A inhibitors and ends with experimental validation. Our computational results emphasized the anticancer effects of MAO-A inhibition and the chemogenomics similarities between clorgyline and structurally diverse groups of apoptosis inducers in addition to highlighting apoptotic, DNA-damage, and microRNAs in cancer pathways. Experimental validation results revealed that MAO inhibition results in antiproliferative antimigratory activities in addition to synergistic effects with doxorubicin. Moreover, the results demonstrated a putative role of MAO-A inhibition in commencing CRC cellular death by potentially mediating the induction of apoptosis.

PBI-05204, a supercritical CO2 extract of Nerium oleander, suppresses glioblastoma stem cells by inhibiting GRP78 and inducing programmed necroptotic cell death

Successful treatment of glioblastoma multiforme (GBM), an aggressive form of primary brain neoplasm, mandates the need to develop new therapeutic strategies. In this study, we investigated the potential of PBI-05204 in targeting GBM stem cells (GSCs) and the underlying mechanisms. Treatment with PBI-05204 significantly reduced both the number and size of tumor spheres derived from patient-derived GSCs (GBM9, GSC28 and TS543), and suppressed the tumorigenesis of GBM9 xenografts. Moreover, PBI-05204 treatment led to a significant decrease in the expression of CD44 and NANOG, crucial markers of progenitor stem cells, in GBM9 and GSC28 GSCs. This treatment also down-regulated GRP78 expression in both GSC types. Knocking down GRP78 expression through GRP78 siRNA transfection in GBM9 and GSC28 GSCs also resulted in reduced spheroid size and CD44 expression. Combining PBI-05204 with GRP78 siRNA further decreased spheroid numbers compared to GRP78 siRNA treatment alone. PBI-05204 treatment led to increased expression of pRIP1K and pRIP3K, along with enhanced binding of RIPK1/RIPK3 in GBM9 and GSC28 cells, resembling the effects observed in GRP78-silenced GSCs, suggesting that PBI-05204 induced necroptosis in these cells. Furthermore, oleandrin, a principle active cardiac glycoside component of PBI-05204, showed the ability to inhibit the self-renewal capacity in GSCs. These findings highlight the potential of PBI-05204 as a promising candidate for the development of novel therapies that target GBM stem cells.

Prospects of compounds of herbal plants as anticancer agents: a comprehensive review from molecular pathways

Cancer refers to the proliferation and multiplication of aberrant cells inside the human body, characterized by their capacity to proliferate and infiltrate various anatomical regions. Numerous biochemical pathways and signaling molecules have an impact on the cancer auto biogenesis process. The regulation of crucial cellular processes necessary for cell survival and proliferation, which are triggered by phytochemicals, is significantly influenced by signaling pathways. These pathways or components are regulated by phytochemicals. Medicinal plants are a significant reservoir of diverse anticancer medications employed in chemotherapy. The anticancer effects of phytochemicals are mediated by several methods, including induction of apoptosis, cessation of the cell cycle, inhibition of kinases, and prevention of carcinogenic substances. This paper analyzes the phytochemistry of seven prominent plant constituents, namely, alkaloids, tannins, flavonoids, phenols, steroids, terpenoids, and saponins, focusing on the involvement of the MAPK/ERK pathway, TNF signaling, death receptors, p53, p38, and actin dynamics. Hence, this review has examined a range of phytochemicals, encompassing their structural characteristics and potential anticancer mechanisms. It has underscored the significance of plant-derived bioactive compounds in the prevention of cancer, utilizing diverse molecular pathways. In addition, this endeavor also seeks to incentivize scientists to carry out clinical trials on anticancer medications derived from plants.

An In Vitro Investigation of the Antiproliferative and Antimetastatic Effects of Levosimendan: Potential Drug Repurposing for Cervical Cancer

Cervical cancer presents a significant challenge to the global health of women. Despite substantial advances in human papillomavirus (HPV)-related cervical cancer vaccines, non-HPV-related cervical cancer is still waiting novel therapeutic options. Drug repurposing has provided a promising approach to improve cancer therapy in recent years. Our study aimed to explore the potential in vitro antineoplastic effects of levosimendan on cervical cancer cells. The antiproliferative effects of levosimendan were investigated on cervical cancer cells using a standard MTT assay. Fluorescent double staining was performed to identify its ability to induce apoptosis and necrosis. The possible mechanism of action of levosimendan was explored using cell-cycle analysis. Furthermore, antimetastatic effects were investigated using a wound-healing assay and a Boyden chamber assay. Our results revealed that levosimendan exhibited the highest growth-inhibitory effect in the HPV-negative C33A cell line. However, the effects were modest compared to the standard agent, cisplatin. Cell-cycle analysis detected that levosimendan can induce cell-cycle arrest in C33A cells by increasing the G1 and G2/M phases, decreasing the S phase, and enhancing the hypodiploid subG1 population. Levosimendan inhibited cell migration and invasion in a concentration-dependent manner. As levosimendan showed antimetastatic efficacy, it could be considered for repurposing to contribute to overcoming resistance to therapy in cervical cancer.

Na+/K+-ATPase: More than an Electrogenic Pump

The sodium pump, or Na+/K+-ATPase (NKA), is an essential enzyme found in the plasma membrane of all animal cells. Its primary role is to transport sodium (Na+) and potassium (K+) ions across the cell membrane, using energy from ATP hydrolysis. This transport creates and maintains an electrochemical gradient, which is crucial for various cellular processes, including cell volume regulation, electrical excitability, and secondary active transport. Although the role of NKA as a pump was discovered and demonstrated several decades ago, it remains the subject of intense research. Current studies aim to delve deeper into several aspects of this molecular entity, such as describing its structure and mode of operation in atomic detail, understanding its molecular and functional diversity, and examining the consequences of its malfunction due to structural alterations. Additionally, researchers are investigating the effects of various substances that amplify or decrease its pumping activity. Beyond its role as a pump, growing evidence indicates that in various cell types, NKA also functions as a receptor for cardiac glycosides like ouabain. This receptor activity triggers the activation of various signaling pathways, producing significant morphological and physiological effects. In this report, we present the results of a comprehensive review of the most outstanding studies of the past five years. We highlight the progress made regarding this new concept of NKA and the various cardiac glycosides that influence it. Furthermore, we emphasize NKA's role in epithelial physiology, particularly its function as a receptor for cardiac glycosides that trigger intracellular signals regulating cell-cell contacts, proliferation, differentiation, and adhesion. We also analyze the role of NKA β-subunits as cell adhesion molecules in glia and epithelial cells.

Cytochrome P450 Mining for Bufadienolide Diversification

Bufadienolides are a class of steroids with a distinctive α-pyrone ring at C17, mostly produced by toads and consisting of over 100 orthologues. They exhibit potent cardiotonic and antitumor activities and are active ingredients of the traditional Chinese medicine Chansu and Cinobufacini. Direct extraction from toads is costly, and chemical synthesis is difficult, limiting the accessibility of active bufadienolides with diverse modifications and trace content. In this work, based on the transcriptome and genome analyses, using a yeast-based screening platform, we obtained eight cytochrome P450 (CYP) enzymes from toads, which catalyze the hydroxylation of bufalin and resibufogenin at different sites. Moreover, a reported fungal CYP enzyme Sth10 was found functioning in the modification of bufalin and resibufogenin at multiple sites. A total of 15 bufadienolides were produced and structurally identified, of which six were first discovered. All of the compounds were effective in inhibiting the proliferation of tumor cells, especially 19-hydroxy-bufalin (2) and 1β-hydroxy-bufalin (3), which were generated from bufalin hydroxylation catalyzed by CYP46A35. The catalytic efficiency of CYP46A35 was improved about six times and its substrate diversity was expanded to progesterone and testosterone, the common precursors for steroid drugs, achieving their efficient and site-specific hydroxylation. These findings elucidate the key modification process in the synthesis of bufadienolides by toads and provide an effective way for the synthesis of unavailable bufadienolides with site-specific modification and active potentials.

Cardiac glycosides inhibit early and late vaccinia virus protein expression

Cardiac glycosides (CGs) are natural steroid glycosides, which act as inhibitors of the cellular sodium-potassium ATPase pump. Although traditionally considered toxic to human cells, CGs are widely used as drugs for the treatment of cardiovascular-related medical conditions. More recently, CGs have been explored as potential anti-viral drugs and inhibit replication of a range of RNA and DNA viruses. Previously, a compound screen identified CGs that inhibited vaccinia virus (VACV) infection. However, no further investigation of the inhibitory potential of these compounds was performed, nor was there investigation of the stage(s) of the poxvirus lifecycle they impacted. Here, we investigated the anti-poxvirus activity of a broad panel of CGs. We found that all CGs tested were potent inhibitors of VACV replication. Our virological experiments showed that CGs did not impact virus infectivity, binding, or entry. Rather, experiments using recombinant viruses expressing reporter proteins controlled by VACV promoters and arabinoside release assays demonstrated that CGs inhibited early and late VACV protein expression at different concentrations. Lack of virus assembly in the presence of CGs was confirmed using electron microscopy. Thus, we expand our understanding of compounds with anti-poxvirus activity and highlight a yet unrecognized mechanism by which poxvirus replication can be inhibited.

Lanatoside C inhibits herpes simplex virus 1 replication by regulating NRF2 distribution within cells

BACKGROUND

In the past decades, extensive research has been conducted to identify new drug targets for the treatment of Herpes simplex virus type 1 (HSV-1) infections. However, the emergence of drug-resistant HSV-1 strains remains a major challenge. This necessitates the identification of new drugs with novel mechanisms of action. Lanatoside C (LanC), a cardiac glycoside (CG) approved by the US Food and Drug Administration (FDA), has demonstrated anticancer and antiviral properties. Nevertheless, its potential as an agent against HSV-1 infections and the underlying mechanism of action are currently unknown.

PURPOSE

This study aimed to investigate the antiviral activity of LanC against HSV-1 and elucidate its molecular mechanisms.

METHODS

The in vitro antiviral activity of LanC was assessed by examining the levels of viral genes, proteins, and virus titers in HSV-1-infected ARPE-19 and Vero cells. Immunofluorescence (IF) analysis was performed to determine the intracellular distribution of NRF2. Additionally, an in vivo mouse model of HSV-1 infection was developed to evaluate the antiviral activity of LanC, using indicators such as intraepidermal nerve fibers (IENFs) loss and viral gene inhibition.

RESULTS

Our findings demonstrate that LanC significantly inhibits HSV-1 replication both in vitro and in vivo. The antiviral effect of LanC is mediated by the perinuclear translocation of NRF2.

CONCLUSIONS

LanC exhibits anti-HSV-1 effects in viral infections, which are associated with the intracellular translocation of NRF2. These findings suggest that LanC has the potential to serve as a novel NRF2 modulator in the treatment of viral diseases.

Transcriptome Profiling of Cardiac Glycoside Treatment Reveals EGR1 and Downstream Proteins of MAPK/ERK Signaling Pathway in Human Breast Cancer Cells

Cardiac glycosides (CGs) constitute a group of steroid-like compounds renowned for their effectiveness in treating cardiovascular ailments. In recent times, there has been growing recognition of their potential use as drug leads in cancer treatment. In our prior research, we identified three highly promising CG compounds, namely lanatoside C (LC), peruvoside (PS), and strophanthidin (STR), which exhibited significant antitumor effects in lung, liver, and breast cancer cell lines. In this study, we investigated the therapeutic response of these CGs, with a particular focus on the MCF-7 breast cancer cell line. We conducted transcriptomic profiling and further validated the gene and protein expression changes induced by treatment through qRT-PCR, immunoblotting, and immunocytochemical analysis. Additionally, we demonstrated the interactions between the ligands and target proteins using the molecular docking approach. The transcriptome analysis revealed a cluster of genes with potential therapeutic targets involved in cytotoxicity, immunomodulation, and tumor-suppressor pathways. Subsequently, we focused on cross-validating the ten most significantly expressed genes, EGR1, MAPK1, p53, CCNK, CASP9, BCL2L1, CDK7, CDK2, CDK2AP1, and CDKN1A, through qRT-PCR, and their by confirming the consistent expression pattern with RNA-Seq data. Notably, among the most variable genes, we identified EGR1, the downstream effector of the MAPK signaling pathway, which performs the regulatory function in cell proliferation, tumor invasion, and immune regulation. Furthermore, we substantiated the influence of CG compounds on translational processes, resulting in an alteration in protein expression upon treatment. An additional analysis of ligand-protein interactions provided further evidence of the robust binding affinity between LC, PS, and STR and their respective protein targets. These findings underscore the intense anticancer activity of the investigated CGs, shedding light on potential target genes and elucidating the probable mechanism of action of CGs in breast cancer.

Unveiling the anti-cancer mechanisms of calotropin: Insights into cell growth inhibition, cell cycle arrest, and metabolic regulation in human oral squamous carcinoma cells (HSC-3)

Background

Calotropin, a cardiac glycoside obtained from the plant Calotropis gigantea, has demonstrated promising potential as an anti-tumorigenesis compound.

Objective

The main objective of this study was to investigate the potential anti-cancer properties of calotropin against HSC-3 oral squamous cancer cells and to elucidate the underlying mechanisms involved in its action.

Material and method

Calotropin were treated in HSC-3 to evaluate cell viability by MTT assay. Flow cytometry analysis divulged that calotropin G0/G1 phase cell cycle arrest and apoptosis in HSC-3 cells. Calotropin displayed inhibitory properties against aerobic glycolysis, a metabolic alteration using glucose uptaken, lactose production and LDHA activity assays. Furthermore, migration and invasion assays help that calotropin has ability to reduce the migratory and invasive of HSC-3 cells, using transwell and Matrigel assay. Validation of mRNA expression through RT-PCR. Molecular docking was implemented to validate the binding association of calotropin with apoptosis and metastatic regulating targets.

Result

The results exemplify that increasing doses of calotropin effectively hold back the HSC-3 cell progression. Migration and invasion assays help that calotropin has ability to reduce the migratory and invasive of HSC-3 cells, indicating its potential to inhibit cancer metastasis. These results imply that calotropin may influence genes linked to metastasis and apoptosis in order to achieve its beneficial effects on cancer. Docking results provided further support, showing a high binding energy between calotropin and metastasis-mediated pathways.

Conclusion

Overall, our findings shed an experimental evidence on how calotropin inhibits the HSC-3 oral squamous cancer cell growth, highlighting the drug's potential as a treatment for oral cancer. Further, investigation on in-vivo experiment is warranted to explore its potential mechanism of action and to develop a novel drug towards clinical trial.

The mechanistic role of cardiac glycosides in DNA damage response and repair signaling

Cardiac glycosides (CGs) are a class of bioactive organic compounds well-known for their application in treating heart disease despite a narrow therapeutic window. Considerable evidence has demonstrated the potential to repurpose CGs for cancer treatment. Chemical modification of these CGs has been utilized in attempts to increase their anti-cancer properties; however, this has met limited success as their mechanism of action is still speculative. Recent studies have identified the DNA damage response (DDR) pathway as a target of CGs. DDR serves to coordinate numerous cellular pathways to initiate cell cycle arrest, promote DNA repair, regulate replication fork firing and protection, or induce apoptosis to avoid the survival of cells with DNA damage or cells carrying mutations. Understanding the modus operandi of cardiac glycosides will provide critical information to better address improvements in potency, reduced toxicity, and the potential to overcome drug resistance. This review summarizes recent scientific findings of the molecular mechanisms of cardiac glycosides affecting the DDR signaling pathway in cancer therapeutics from 2010 to 2022. We focus on the structural and functional differences of CGs toward identifying the critical features for DDR targeting of these agents.

Induced Vascular Normalization-Can One Force Tumors to Surrender to a Better Microenvironment?

Immunotherapy has changed the way many cancers are being treated. Researchers in the field of immunotherapy and tumor immunology are investigating similar questions: How can the positive benefits achieved with immunotherapies be enhanced? Can this be achieved through combinations with other agents and if so, which ones? In our view, there is an urgent need to improve immunotherapy to make further gains in the overall survival for those patients that should benefit from immunotherapy. While numerous different approaches are being considered, our team believes that drug delivery methods along with appropriately selected small-molecule drugs and drug candidates could help reach the goal of doubling the overall survival rate that is seen in some patients that are given immunotherapeutics. This review article is prepared to address how immunotherapies should be combined with a second treatment using an approach that could realize therapeutic gains 10 years from now. For context, an overview of immunotherapy and cancer angiogenesis is provided. The major targets in angiogenesis that have modulatory effects on the tumor microenvironment and immune cells are highlighted. A combination approach that, for us, has the greatest potential for success involves treatments that will normalize the tumor's blood vessel structure and alter the immune microenvironment to support the action of immunotherapeutics. So, this is reviewed as well. Our focus is to provide an insight into some strategies that will engender vascular normalization that may be better than previously described approaches. The potential for drug delivery systems to promote tumor blood vessel normalization is considered.

Phytochemical profiling and cytotoxic potential of Arnebia nobilis root extracts against hepatocellular carcinoma using in-vitro and in-silico approaches

Hepatocellular carcinoma is the fifth most prevalent cancer worldwide. The emergence of drug resistance and other adverse effects in available anticancer options are challenging to explore natural sources. The current study was designed to decipher the Arnebia nobilis (A. nobilis) extracts for detecting phytochemicals, in-vitro evaluation of antioxidative and cytotoxic potentials, and in-silico prediction of potent anticancer compounds. The phytochemical analysis revealed the presence of flavonoids, phenols, tannins, alkaloids, quinones, and cardiac glycosides, in the ethanol (ANE) and n-hexane (ANH) extracts of A. nobilis. ANH extract exhibited a better antioxidant potential to scavenge DPPH, nitric oxide and superoxide anion radicals than ANE extract, which showed better potential only against H2O2 radicals. In 24 h treatment, ANH extract revealed higher cytotoxicity (IC50 value: 22.77 µg/mL) than ANH extract (IC50 value: 46.74 µg/mL) on cancer (HepG2) cells without intoxicating the normal (BHK) cells using MTT assay. A better apoptotic potential was observed in ANH extract (49.10%) compared to ANE extract (41.35%) on HepG2 cells using the annexin V/PI method. GCMS analysis of ANH extract identified 35 phytocompounds, from which only 14 bioactive compounds were selected for molecular docking based on druggability criteria and toxicity filters. Among the five top scorers, deoxyshikonin exhibited the best binding affinities of - 7.2, - 9.2, - 7.2 and - 9.2 kcal/mol against TNF-α, TGF-βR1, Bcl-2 and iNOS, respectively, followed by ethyl cholate and 2-Methyl-6-(4-methylphenyl)hept-2-en-4-one along with their desirable ADMET properties. The phytochemicals of ANH extract could be used as a promising drug candidate for liver cancer after further validations.

The Cytotoxic Cardiac Glycoside (-)-Cryptanoside A from the Stems of Cryptolepis dubia and Its Molecular Targets

A cardiac glycoside epoxide, (-)-cryptanoside A (1), was isolated from the stems of Cryptolepis dubia collected in Laos, for which the complete structure was confirmed by analysis of its spectroscopic and single-crystal X-ray diffraction data, using copper radiation at a low temperature. This cardiac glycoside epoxide exhibited potent cytotoxicity against several human cancer cell lines tested, including HT-29 colon, MDA-MB-231 breast, OVCAR3 and OVCAR5 ovarian cancer, and MDA-MB-435 melanoma cells, with the IC50 values found to be in the range 0.1-0.5 μM, which is comparable with that observed for digoxin. However, it exhibited less potent activity (IC50 1.1 μM) against FT194 benign/nonmalignant human fallopian tube secretory epithelial cells when compared with digoxin (IC50 0.16 μM), indicating its more selective activity toward human cancer versus benign/nonmalignant cells. (-)-Cryptanoside A (1) also inhibited Na+/K+-ATPase activity and increased the expression of Akt and the p65 subunit of NF-κB but did not show any effects on the expression of PI3K. A molecular docking profile showed that (-)-cryptanoside A (1) binds to Na+/K+-ATPase, and thus 1 may directly target Na+/K+-ATPase to mediate its cancer cell cytotoxicity.

Bintaro (Cerbera odollam and Cerbera manghas): an overview of its eco-friendly use, pharmacology, and toxicology

Bintaro is a tropical mangrove plant often used as a shade tree found in Asia, Australia, Madagascar, and the Islands of the Western Pacific Ocean. The word Bintaro is also often pinned to its closest relative species, the Cerbera odollam. Flower color is one of the distinguishing features between these two species. Human poisoning with the cardiotoxic plant Bintaro is common in Southeast Asia because it bears a fruit that yields a powerful poison that has been used for suicide and homicide, hence it is also called the "Indian suicide tree". The seeds of Bintaro contain Cerberin, a cardiac glycoside toxin of the heart that blocks the calcium ion channels in heart muscles, resulting in disruption of the heartbeat most often fatally. The bio-active compound in the kernels of Bintaro varies due to which plant possesses other properties as well. The plant may also be used for medicinal purposes as it shows many pharmaceutical properties. The seeds of the plant have auspicious anticancer properties through apoptotic activity and the leaf extract of the plant was screened for its antioxidant activities. In addition, it is also used as an insecticide, pesticide, or antifungal agent. This review highlights the Pharmaceutical, toxicological, and environmentally friendly approaches of Bintaro.

Involvement of monocyte-derived extracellular vesicle-associated tissue factor activity in convallatoxin-induced hypercoagulability

OBJECTIVES

Convallatoxin (CNT) is a natural cardiac glycoside extracted from lily of the valley ( Convallaria majalis ). Although it is empirically known to cause blood coagulation disorders, the underlying mechanism remains unclear. CNT exerts cytotoxicity and increases tissue factor (TF) expression in endothelial cells. However, the direct action of CNT on blood coagulation remains unclear. Therefore, herein, we investigated the effects of CNT on whole blood coagulation system and TF expression in monocytes.

METHODS

Blood samples were collected from healthy volunteers to measure plasma thrombin-antithrombin complex (TAT) concentration using ELISA and to perform rotational thromboelastometry (ROTEM) and whole-blood extracellular vesicle (EV)-associated TF (EV-TF) analysis. The effects of CNT were also investigated using the monocytic human cell line THP-1. Quantitative real-time PCR and western blotting were performed, and PD98059, a mitogen-activated protein kinase (MAPK) inhibitor, was used to elucidate the action mechanism of CNT-mediated TF production.

RESULTS

CNT treatment increased EV-TF activity, shortened the whole blood clotting time in rotational thromboelastometry analysis, and increased TAT levels, which is an index of thrombin generation. Furthermore, CNT increased TF mRNA expression in THP-1 cells and EV-TF activity in the cell culture supernatant. Therefore, CNT may induce a hypercoagulable state with thrombin generation, in which elevated EV-TF activity derived from monocytes might be involved. These procoagulant effects of CNT were reversed by PD98059, suggesting that CNT-induced TF production in monocytes might be mediated by the MAPK pathway.

CONCLUSIONS

The findings of the present study have further clarified the procoagulant properties of CNT.

Quantification of plant cardenolides by HPLC, measurement of Na+/K+-ATPase inhibition activity, and characterization of target enzymes

The biosynthesis of cardiac glycosides, broadly classified as cardenolides and bufadienolides, has evolved repeatedly among flowering plants. Individual species can produce dozens or even hundreds of structurally distinct cardiac glycosides. Although all cardiac glycosides exhibit biological activity by inhibiting the function of the essential Na⁺/K⁺-ATPase in animal cells, they differ in their level of inhibitory activity. For within- and between-species comparisons of cardiac glycosides to address ecological and evolutionary questions, it is necessary to not only quantify their relative abundance, but also their effectiveness in inhibiting the activity of different animal Na⁺/K⁺-ATPases. Here we describe protocols for characterizing the amount and toxicity of cardenolides from plant samples and the degree of insect Na⁺/K⁺-ATPase tolerance to inhibition: (1) an HPLC-based assay to quantify the abundance of individual cardenolides in plant extracts, (2) an assay to quantify inhibition of Na⁺/K⁺-ATPase activity by plant extracts, and (3) extraction of insect Na⁺/K⁺-ATPases for inhibition assays.

Drug Repurposing: A New Hope in Drug Discovery for Prostate Cancer

Prostate cancer (PCA), the most common cancer in men, accounted for 1.3 million new incidences in 2018. An increase in incidences is an issue of concern that should be addressed. Of all the reported prostate cancers, 85% were detected in stages III and IV, making them difficult to treat. Conventional drugs gradually lose their efficacy due to the developed resistance against them, thus requiring newer therapeutic agents to be used as monotherapy or combination. Recent research regarding treatment options has attained remarkable speed and development. Therefore, in this context, drug repurposing comes into the picture, which is defined as the "investigation of the off-patent, approved and marketed drugs for a novel therapeutic indication" which saves at least 30% of the time and cost, reducing the cost of treatment for patients, which usually runs high in cancer patients. The anticancer property of cardiac glycosides in cancers was tested in the early 1980s. The trend then shifts toward treating prostate cancer by repurposing other cardiovascular drugs. The current review mainly emphasizes the advantageous antiprostate cancer profile of conventional CVS drugs like cardiac glycosides, RAAS inhibitors, statins, heparin, and beta-blockers with underlying mechanisms.

Cardiac glycosides from the roots of Streblus asper Lour. with activity against Epstein-Barr virus lytic replication

Cardiac glycosides (CGs) show potential broad-spectrum antiviral activity by targeting cellular host proteins. Herein are reported the isolation of five new (1-5) and eight known (7-13) CGs from the roots of Streblus asper Lour. Of these compounds 1 and 7 exhibited inhibitory action against EBV early antigen (EA) expression, with half-maximal effective concentration values (EC₅₀) being less than 60 nM, and they also showed selectivity, with selectivity index (SI) values being 56.80 and 103.17, respectively. Preliminary structure activity relationships indicated that the C-10 substituent, C-5 hydroxy groups, and C-3 sugar unit play essential roles in the mediation of the inhibitory activity of CGs against EBV. Further enzyme experiments demonstrated that these compounds might inhibit ion pump function and thereby change the intracellular signal transduction pathway by binding to Na⁺/K⁺-ATPase, as validated by simulated molecular docking. This study is the first report that CGs can effectively limit EBV lytic replication, and the observations made in this study may be of value for lead compound development.

Peruvoside is a novel Src inhibitor that suppresses NSCLC cell growth and motility by downregulating multiple Src-EGFR-related pathways

The tyrosine kinase Src plays an essential role in the progression of many cancers and is involved in several epidermal growth factor receptor (EGFR)-mediated signalling pathways. To improve the efficacy of lung cancer treatments, this study aimed to identify novel compounds that can disrupt the Src-EGFR interaction and that are less dependent on EGFR status with wild-type and mutations than other compounds. We used the Src pY419 ELISA as the platform to screen a compound library of more than 400 plant-derived active ingredients and identified peruvoside as a candidate Src-EGFR crosstalk inhibitor. The effects of peruvoside were evaluated by western blotting, cell function assays, combination Index (CI)-isobologram analyses and in vivo experiments. Peruvoside significantly suppressed the phosphorylation of Src, EGFR, and signal transducer and activator of transcription 3 (STAT3) in a dose- and time-dependent manner and somewhat suppressed their protein expression. Cell function assays revealed that peruvoside inhibited the proliferation, invasion, migration, and colony formation of lung cancer cells in vitro and tumour growth in vivo. Furthermore, peruvoside sensitized gefitinib-resistant tumour cells (A549, PC9/gef and H1975) to gefitinib treatment, indicating that peruvoside may exert synergistic effects when used in combination with established therapeutic agents. Our data also demonstrated that the inhibitory effects of peruvoside on lung cancer progression might be attributed to its ability to regulate Src, phosphoinositide 3-kinase (PI3K), c-Jun N-terminal kinase (JNK), Paxillin, p130cas, and EGFR. Our findings suggest that peruvoside suppresses non-small-cell lung carcinoma (NSCLC) malignancy by downregulating multiple Src-related pathways and could serve as a potential base molecule for developing new anticancer drugs and therapeutic strategies for lung cancer.

Drug repositioning: Progress and challenges in drug discovery for various diseases

Compared with traditional de novo drug discovery, drug repurposing has become an attractive drug discovery strategy due to its low-cost and high efficiency. Through a comprehensive analysis of the candidates that have been identified with drug repositioning potentials, it is found that although some drugs do not show obvious advantages in the original indications, they may exert more obvious effects in other diseases. In addition, some drugs have a synergistic effect to exert better clinical efficacy if used in combination. Particularly, it has been confirmed that drug repositioning has benefits and values on the current public health emergency such as the COVID-19 pandemic, which proved the great potential of drug repositioning. In this review, we systematically reviewed a series of representative drugs that have been repositioned for different diseases and illustrated successful cases in each disease. Especially, the mechanism of action for the representative drugs in new indications were explicitly explored for each disease, we hope this review can provide important insights for follow-up research.

A review of chemical defense in harlequin toads (Bufonidae: Atelopus)

Toads of the genus Atelopus are chemically defended by a unique combination of endogenously synthesized cardiotoxins (bufadienolides) and neurotoxins which may be sequestered (guanidinium alkaloids). Investigation into Atelopus small-molecule chemical defenses has been primarily concerned with identifying and characterizing various forms of these toxins while largely overlooking their ecological roles and evolutionary implications. In addition to describing the extent of knowledge about Atelopus toxin structures, pharmacology, and biological sources, we review the detection, identification, and quantification methods used in studies of Atelopus toxins to date and conclude that many known toxin profiles are unlikely to be comprehensive because of methodological and sampling limitations. Patterns in existing data suggest that both environmental (toxin availability) and genetic (capacity to synthesize or sequester toxins) factors influence toxin profiles. From an ecological and evolutionary perspective, we summarize the possible selective pressures acting on Atelopus toxicity and toxin profiles, including predation, intraspecies communication, disease, and reproductive status. Ultimately, we intend to provide a basis for future ecological, evolutionary, and biochemical research on Atelopus.

Cardiac glycosides from Digitalis lanata and their cytotoxic activities

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities. In this study, fifteen CGs including three new ones (1–3) were isolated from Digitalis lanata Ehrh. Their structures were elucidated by HRESIMS, NMR spectroscopic methods, including homonuclear and heteronuclear coupling constant analysis, and acid-catalyzed hydrolysis and derivatization analysis of the sugar chain. The cytotoxic activities of these CGs were evaluated against three human cancer cell lines (A549, HeLa and MCF-7 cell lines), and all of them showed strong activities at nanomolar scale. The flow cytometric analysis indicated that compound 1 induced cell cycle arrest in the G2/M phase. Transcriptome analysis revealed a panel of possible targets for compound 1. RT-PCR and western blot experiments showed that 1 significantly inhibited the expression of vasohibin-2 (VASH2). Moreover, compound 1 restrained angiogenesis in a concentration-dependent manner in the chick embryo chorioallantoic membrane (CAM) model.

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities.

Depth of the Steroid Core Location Determines the Mode of Na,K-ATPase Inhibition by Cardiotonic Steroids

Cardiotonic steroids (CTSs) are specific inhibitors of Na,K-ATPase (NKA). They induce diverse physiological effects and were investigated as potential drugs in heart diseases, hypertension, neuroinflammation, antiviral and cancer therapy. Here, we compared the inhibition mode and binding of CTSs, such as ouabain, digoxin and marinobufagenin to NKA from pig and rat kidneys, containing CTSs-sensitive (α1S) and -resistant (α1R) α1-subunit, respectively. Marinobufagenin in contrast to ouabain and digoxin interacted with α1S-NKA reversibly, and its binding constant was reduced due to the decrease in the deepening in the CTSs-binding site and a lower number of contacts between the site and the inhibitor. The formation of a hydrogen bond between Arg111 and Asp122 in α1R-NKA induced the reduction in CTSs’ steroid core deepening that led to the reversible inhibition of α1R-NKA by ouabain and digoxin and the absence of marinobufagenin’s effect on α1R-NKA activity. Our results elucidate that the difference in signaling, and cytotoxic effects of CTSs may be due to the distinction in the deepening of CTSs into the binding side that, in turn, is a result of a bent-in inhibitor steroid core (marinobufagenin in α1S-NKA) or the change of the width of CTSs-binding cavity (all CTSs in α1R-NKA).

Broad Spectrum Antiviral Properties of Cardiotonic Steroids Used as Potential Therapeutics for Emerging Coronavirus Infections

Cardiotonic steroids are steroid-like natural compounds known to inhibit Na⁺/K⁺-ATPase pumps. To develop a broad-spectrum antiviral drug against the emerging coronavirus infection, this study assessed the antiviral properties of these compounds. The activity of seven types of cardiotonic steroids against the MERS-CoV, SARS-CoV, and SARS-CoV-2 coronavirus varieties was analyzed using immunofluorescence antiviral assay in virus-infected cells. Bufalin, cinobufagin, and telocinobufagin showed high anti-MERS-CoV activities (IC₅₀, 0.017~0.027 μM); bufalin showed the most potent anti-SARS-CoV and SARS-CoV-2 activity (IC₅₀, 0.016~0.019 μM); cinobufotalin and resibufogenin showed comparatively low anti-coronavirus activity (IC₅₀, 0.231~1.612 μM). Differentially expressed genes in Calu3 cells treated with cinobufagin, telocinobufagin, or bufalin, which had high antiviral activity during MERS-CoV infection were analyzed using QuantSeq 3' mRNA-Seq analysis and data showed similar gene expression patterns. Furthermore, the intraperitoneal administration of 10 mg/kg/day bufalin, cinobufagin, or digitoxin induced 100% death after 1, 2, and 4 days in 5-day repeated dose toxicity studies and it indicated that bufalin had the strongest toxicity. Pharmacokinetic studies suggested that telocinobufagin, which had high anti-coronavirus activity and low toxicity, had better microsomal stability, lower CYP inhibition, and better oral bioavailability than cinobufagin. Therefore, telocinobufagin might be the most promising cardiotonic steroid as a therapeutic for emerging coronavirus infections, including COVID-19.

Novel therapeutic drug strategies to tackle immune-oncological challenges faced by cancer patients during COVID-19

INTRODUCTION

For the clinical treatment of cancer patients, coronavirus (SARS-CoV-2) can cause serious immune-related problems. Cancer patients, who experience immunosuppression due to the pathogenesis and severity of disease, may become more aggressive due to multiple factors such as age, comorbidities, and immunosuppression. In this pandemic era, COVID-19 causes lymphopenia, cancer cell awakening, inflammatory diseases, and a cytokine storm that worsens disease-related morbidity and prognosis.

AREAS COVERED

We discuss all the risk factors of COVID-19 associated with cancer patients and propose new strategies to use antiviral and anticancer drugs for therapeutic purposes. We bring new drugs, cancers and COVID-19 treatment strategies together to address the immune system challenges faced by oncologists.

EXPERT OPINION

The chronic inflammatory microenvironment caused by COVID-19 awakens dormant cancer cells through inflammation and autoimmune activation. Drug-related strategies to ensure that clinical treatment can reduce the susceptibility of cancer patients to COVID-19, and possible counter-measures to minimize the harm caused by the COVID-19 have been outlined. The response to the pandemic and recovery has been elaborated, which can provide information for long-term cancer treatment and speed up the optimization process.

Cancer-specific calcium nanoregulator suppressing the generation and circulation of circulating tumor cell clusters for enhanced anti-metastasis combinational chemotherapy

Tumor metastasis is responsible for chemotherapeutic failure and cancer-related death. Moreover, circulating tumor cell (CTC) clusters play a pivotal role in tumor metastasis. Herein, we develop cancer-specific calcium nanoregulators to suppress the generation and circulation of CTC clusters by cancer membrane-coated digoxin (DIG) and doxorubicin (DOX) co-encapsulated PLGA nanoparticles (CPDDs). CPDDs could precisely target the homologous primary tumor cells and CTC clusters in blood and lymphatic circulation. Intriguingly, CPDDs induce the accumulation of intracellular Ca²⁺ by inhibiting Na⁺/K⁺-ATPase, which help restrain cell–cell junctions to disaggregate CTC clusters. Meanwhile, CPDDs suppress the epithelial–mesenchymal transition (EMT) process, resulting in inhibiting tumor cells escape from the primary site. Moreover, the combination of DOX and DIG at a mass ratio of 5:1 synergistically induces the apoptosis of tumor cells. In vitro and in vivo results demonstrate that CPDDs not only effectively inhibit the generation and circulation of CTC clusters, but also precisely target and eliminate primary tumors. Our findings present a novel approach for anti-metastasis combinational chemotherapy.

Emergence of Cardiac Glycosides as Potential Drugs: Current and Future Scope for Cancer Therapeutics

Cardiac glycosides are natural sterols and constitute a group of secondary metabolites isolated from plants and animals. These cardiotonic agents are well recognized and accepted in the treatment of various cardiac diseases as they can increase the rate of cardiac contractions by acting on the cellular sodium potassium ATPase pump. However, a growing number of recent efforts were focused on exploring the antitumor and antiviral potential of these compounds. Several reports suggest their antitumor properties and hence, today cardiac glycosides (CG) represent the most diversified naturally derived compounds strongly recommended for the treatment of various cancers. Mutated or dysregulated transcription factors have also gained prominence as potential therapeutic targets that can be selectively targeted. Thus, we have explored the recent advances in CGs mediated cancer scope and have considered various signaling pathways, molecular aberration, transcription factors (TFs), and oncogenic genes to highlight potential therapeutic targets in cancer management.

Targeting Na+ /K+ -ATPase by berbamine and ouabain synergizes with sorafenib to inhibit hepatocellular carcinoma

BACKGROUND AND PURPOSE

The multikinase inhibitor sorafenib is a first-line drug for advanced hepatocellular carcinoma. The response to sorafenib varies among hepatocellular carcinoma patients and many of the responders suffer from reduced sensitivity after long-term treatment. This study aims to explore a novel strategy to potentiate or maximize the anti-hepatocellular carcinoma effects of sorafenib.

EXPERIMENTAL APPROACH

We used hepatocellular carcinoma cell lines, western blotting, various antagonists, siRNA and tumour xenografts mouse model to determine the anti- hepatocellular carcinoma effects of sorafenib in combination with berbamine or other Na⁺ /K⁺ -ATPase ligands.

KEY RESULTS

Berbamine and the cardiotonic steroid, ouabain, synergize with sorafenib to inhibit hepatocellular carcinoma cells growth. Mechanistically, berbamine induces Src phosphorylation in Na⁺ /K⁺ -ATPase-dependent manner, leading to the activation of p38MAPK and EGFR-ERK pathways. The Na⁺ /K⁺ -ATPase ligand ouabain also induces Src, EGFR, type I insulin-like growth factor receptor, ERK1/2 and p38MAPK phosphorylation in hepatocellular carcinoma cells. Treatment of hepatocellular carcinoma cells with Src or EGFR inhibitor inhibits the induction of ERK1/2 phosphorylation by berbamine. Moreover, sorafenib inhibits the induction of Src, p38MAPK, EGFR and ERK1/2 phosphorylation by berbamine and ouabain. Importantly, combination of sorafenib with berbamine or ouabain synergistically inhibits both sorafenib-naïve and sorafenib-resistant hepatocellular carcinoma cells growth. Co-treatment of hepatocellular carcinoma cells with berbamine and sorafenib significantly induces cell death and significantly inhibits hepatocellular carcinoma xenografts growth in vivo.

CONCLUSION AND IMPLICATIONS

Berbamine or other Na⁺ /K⁺ -ATPase ligands have a potential for improving sorafenib responsiveness in hepatocellular carcinoma. Targeting Na⁺ /K⁺ -ATPase represents a novel strategy to potentiate the anti- hepatocellular carcinoma effects of sorafenib.

Anticancer potential of cardiac glycosides and steroid-azole hybrids

Steriods are well-known scaffolds that have a widespread occurrence in different compounds characterized by extensive biological properties including anticancer activity. Structural modifications on steroids always generate potential lead compounds with superior bioactivity, and creation of steroid hybrids by combining steroid with other anticancer pharmacophores in one molecule, which can exert the anticancer activity through different mechanisms, is one of the most promising strategies to enhance efficiency, overcome drug resistance and reduce side effects. Sugars and azoles, can act on diverse receptors, proteins and enzymes in cancer cells, are pharmacologically significant scaffolds in the development of novel anticancer agents. Therefore, steroid-sugar hybrids cardiac glycosides and steroid-azole hybrids are privileged scaffolds for the discovery of novel anticancer candidates. This review emphasized on the development, the structure-activity relationship and the mechanism of action of cardiac glycosides and steroid-azole hybrids with potential application for fighting against various cancers including drug-resistant forms to facilitate further rational design of novel drug candidates covering articles published between 2015 and 2020.

Cardiac Glycosides as Immune System Modulators

Cardiac glycosides (CGs) are natural steroid compounds occurring both in plants and animals. They are known for long as cardiotonic agents commonly used for various cardiac diseases due to inhibition of Na⁺/K⁺-ATPase (NKA) pumping activity and modulating heart muscle contractility. However, recent studies show that the portfolio of diseases potentially treatable with CGs is much broader. Currently, CGs are mostly studied as anticancer agents. Their antiproliferative properties are based on the induction of multiple signaling pathways in an NKA signalosome complex. In addition, they are strongly connected to immunogenic cell death, a complex mechanism of induction of anticancer immune response. Moreover, CGs exert various immunomodulatory effects, the foremost of which are connected with suppressing the activity of T-helper cells or modulating transcription of many immune response genes by inhibiting nuclear factor kappa B. The resulting modulations of cytokine and chemokine levels and changes in immune cell ratios could be potentially useful in treating sundry autoimmune and inflammatory diseases. This review aims to summarize current knowledge in the field of immunomodulatory properties of CGs and emphasize the large area of potential clinical use of these compounds.

Na+/K+-ATPase Revisited: On Its Mechanism of Action, Role in Cancer, and Activity Modulation

Maintenance of Na⁺ and K⁺ gradients across the cell plasma membrane is an essential process for mammalian cell survival. An enzyme responsible for this process, sodium-potassium ATPase (NKA), has been currently extensively studied as a potential anticancer target, especially in lung cancer and glioblastoma. To date, many NKA inhibitors, mainly of natural origin from the family of cardiac steroids (CSs), have been reported and extensively studied. Interestingly, upon CS binding to NKA at nontoxic doses, the role of NKA as a receptor is activated and intracellular signaling is triggered, upon which cancer cell death occurs, which lies in the expression of different NKA isoforms than in healthy cells. Two major CSs, digoxin and digitoxin, originally used for the treatment of cardiac arrhythmias, are also being tested for another indication—cancer. Such drug repositioning has a big advantage in smoother approval processes. Besides this, novel CS derivatives with improved performance are being developed and evaluated in combination therapy. This article deals with the NKA structure, mechanism of action, activity modulation, and its most important inhibitors, some of which could serve not only as a powerful tool to combat cancer, but also help to decipher the so-far poorly understood NKA regulation.

Preeclampsia: Cardiotonic Steroids, Fibrosis, Fli1 and Hint to Carcinogenesis

Despite prophylaxis and attempts to select a therapy, the frequency of preeclampsia does not decrease and it still takes the leading position in the structure of maternal mortality and morbidity worldwide. In this review, we present a new theory of the etiology and pathogenesis of preeclampsia that is based on the interaction of Na/K-ATPase and its endogenous ligands including marinobufagenin. The signaling pathway of marinobufagenin involves an inhibition of transcriptional factor Fli1, a negative regulator of collagen synthesis, followed by the deposition of collagen in the vascular tissues and altered vascular functions. Moreover, in vitro and in vivo neutralization of marinobufagenin is associated with the restoration of Fli1. The inverse relationship between marinobufagenin and Fli1 opens new possibilities in the treatment of cancer; as Fli1 is a proto-oncogene, a hypothesis on the suppression of Fli1 by cardiotonic steroids as a potential anti-tumor therapeutic strategy is discussed as well. We propose a novel therapy of preeclampsia that is based on immunoneutralization of the marinobufagenin by monoclonal antibodies, which is capable of impairing marinobufagenin-Na/K-ATPase interactions.

Cytotoxicity of glucoevatromonoside alone and in combination with chemotherapy drugs and their effects on Na+,K+-ATPase and ion channels on lung cancer cells

Cardiac glycosides (CGs) are useful drugs to treat cardiac illnesses and have potent cytotoxic and anticancer effects in cultured cells and animal models. Their receptor is the Na⁺,K⁺ ATPase, but other plasma membrane proteins might bind CGs as well. Herein, we evaluated the short- and long-lasting cytotoxic effects of the natural cardenolide glucoevatromonoside (GEV) on non-small-cell lung cancer H460 cells. We also tested GEV effects on Na⁺,K⁺ -ATPase activity and membrane currents, alone or in combination with selected chemotherapy drugs. GEV reduced viability, migration, and invasion of H460 cells spheroids. It also induced cell cycle arrest and death and reduced the clonogenic survival and cumulative population doubling. GEV inhibited Na⁺,K⁺-ATPase activity on A549 and H460 cells and purified pig kidney cells membrane. However, it showed no activity on the human red blood cell plasma membrane. Additionally, GEV triggered a Cl-mediated conductance on H460 cells without affecting the transient voltage-gated sodium current. The administration of GEV in combination with the chemotherapeutic drugs paclitaxel (PAC), cisplatin (CIS), irinotecan (IRI), and etoposide (ETO) showed synergistic antiproliferative effects, especially when combined with GEV + CIS and GEV + PAC. Taken together, our results demonstrate that GEV is a potential drug for cancer therapy because it reduces lung cancer H460 cell viability, migration, and invasion. Our results also reveal a link between the Na⁺,K⁺-ATPase and Cl^- ion channels.

Semisynthetic Cardenolides Acting as Antiviral Inhibitors of Influenza A Virus Replication by Preventing Polymerase Complex Formation

Influenza virus infections represent a major public health issue by causing annual epidemics and occasional pandemics that affect thousands of people worldwide. Vaccination is the main prophylaxis to prevent these epidemics/pandemics, although the effectiveness of licensed vaccines is rather limited due to the constant mutations of influenza virus antigenic characteristics. The available anti-influenza drugs are still restricted and there is an increasing viral resistance to these compounds, thus highlighting the need for research and development of new antiviral drugs. In this work, two semisynthetic derivatives of digitoxigenin, namely C10 (3β-((N-(2-hydroxyethyl)aminoacetyl)amino-3-deoxydigitoxigenin) and C11 (3β-(hydroxyacetyl)amino-3-deoxydigitoxigenin), showed anti-influenza A virus activity by affecting the expression of viral proteins at the early and late stages of replication cycle, and altering the transcription and synthesis of new viral proteins, thereby inhibiting the formation of new virions. Such antiviral action occurred due to the interference in the assembly of viral polymerase, resulting in an impaired polymerase activity and, therefore, reducing viral replication. Confirming the in vitro results, a clinically relevant ex vivo model of influenza virus infection of human tumor-free lung tissues corroborated the potential of these compounds, especially C10, to completely abrogate influenza A virus replication at the highest concentration tested (2.0 µM). Taken together, these promising results demonstrated that C10 and C11 can be considered as potential new anti-influenza drug candidates.