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.

Cardiac glycoside ouabain efficiently targets leukemic stem cell apoptotic machinery independent of cell differentiation status.

BACKGROUND: Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by an accumulation of immature leukemic myeloblasts initiating from leukemic stem cells (LSCs)-the subpopulation that is also considered the root cause of chemotherapy resistance. Repurposing cardiac glycosides to treat cancers has gained increasing attention and supporting evidence, but how cardiac glycosides effectively target LSCs, e.g., whether it involves cell differentiation, remains largely unexplored. METHODS: Digoxin, a user-designed digitoxigenin-α-L-rhamnoside (D6-MA), and ouabain were tested against various human AML-derived cells with different maturation phenotypes. Herein, we established two study models to specifically determine the effects of cardiac glycosides on LSC death and differentiation-one allowed change in dynamics of LSCs and leukemic progenitor cells (LPCs), while another maintained their undifferentiated status. Regulatory mechanisms underlying cardiac glycoside-induced cytotoxicity were investigated and linked to cell cycle distribution and apoptotic machinery. RESULTS: Primitive AML cells containing CD34+ LSCs/LPCs were very responsive to nanomolar concentrations of cardiac glycosides, with ouabain showing the greatest efficiency. Ouabain preferentially induces caspase-dependent apoptosis in LSCs, independent of its cell differentiation status, as evidenced by (i) the tremendous induction of apoptosis by ouabain in AML cells that acquired less than 15% differentiation and (ii) the higher rate of apoptosis in enriched LSCs than in LPCs. We sorted LSCs and LPCs according to their cell cycle distribution into G0/G1, S, and G2/M cells and revealed that G0/G1 cells in LSCs, which was its major subpopulation, were the top ouabain responders, indicating that the difference in ouabain sensitivity between LSCs and LPCs involved both distinct cell cycle distribution and intrinsic apoptosis regulatory mechanisms. Further, Mcl-1 and c-Myc, which were differentially expressed in LSCs and LPCs, were found to be the key apoptosis mediators that determined ouabain sensitivity in AML cells. Ouabain induces a more rapid loss of Mcl-1 and c-Myc in LSCs than in LPCs via the mechanisms that in part involve an inhibition of Mcl-1 protein synthesis and an induction of c-Myc degradation. CONCLUSIONS: Our data provide new insight for repurposing cardiac glycosides for the treatment of relapsed/refractory AML through targeting LSCs via distinct cell cycle and apoptosis machinery. Video Abstract.

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.

New Insights on the Role of Marinobufagenin from Bench to Bedside in Cardiovascular and Kidney Diseases.

Marinobufagenin (MBG) is a member of the bufadienolide family of compounds, which are natural cardiac glycosides found in a variety of animal species, including man, which have different physiological and biochemical functions but have a common action on the inhibition of the adenosine triphosphatase sodium-potassium pump (Na+/K+-ATPase). MBG acts as an endogenous cardiotonic steroid, and in the last decade, its role as a pathogenic factor in various human diseases has emerged. In this paper, we have collated major evidence regarding the biological characteristics and functions of MBG and its implications in human pathology. This review focused on MBG involvement in chronic kidney disease, including end-stage renal disease, cardiovascular diseases, sex and gender medicine, and its actions on the nervous and immune systems. The role of MBG in pathogenesis and the development of a wide range of pathological conditions indicate that this endogenous peptide could be used in the future as a diagnostic biomarker and/or therapeutic target, opening important avenues of scientific research.

The cardiac glycoside ZINC253504760 induces parthanatos-type cell death and G2/M arrest via downregulation of MEK1/2 phosphorylation in leukemia cells.

Overcoming multidrug resistance (MDR) represents a major obstacle in cancer chemotherapy. Cardiac glycosides (CGs) are efficient in the treatment of heart failure and recently emerged in a new role in the treatment of cancer. ZINC253504760, a synthetic cardenolide that is structurally similar to well-known GCs, digitoxin and digoxin, has not been investigated yet. This study aims to investigate the cytotoxicity of ZINC253504760 on MDR cell lines and its molecular mode of action for cancer treatment. Four drug-resistant cell lines (P-glycoprotein-, ABCB5-, and EGFR-overexpressing cells, and TP53-knockout cells) did not show cross-resistance to ZINC253504760 except BCRP-overexpressing cells. Transcriptomic profiling indicated that cell death and survival as well as cell cycle (G2/M damage) were the top cellular functions affected by ZINC253504760 in CCRF-CEM cells, while CDK1 was linked with the downregulation of MEK and ERK. With flow cytometry, ZINC253504760 induced G2/M phase arrest. Interestingly, ZINC253504760 induced a novel state-of-the-art mode of cell death (parthanatos) through PARP and PAR overexpression as shown by western blotting, apoptosis-inducing factor (AIF) translocation by immunofluorescence, DNA damage by comet assay, and mitochondrial membrane potential collapse by flow cytometry. These results were ROS-independent. Furthermore, ZINC253504760 is an ATP-competitive MEK inhibitor evidenced by its interaction with the MEK phosphorylation site as shown by molecular docking in silico and binding to recombinant MEK by microscale thermophoresis in vitro. To the best of our knowledge, this is the first time to describe a cardenolide that induces parthanatos in leukemia cells, which may help to improve efforts to overcome drug resistance in cancer. A cardiac glycoside compound ZINC253504760 displayed cytotoxicity against different multidrug-resistant cell lines. ZINC253504760 exhibited cytotoxicity in CCRF-CEM leukemia cells by predominantly inducing a new mode of cell death (parthanatos). ZINC253504760 downregulated MEK1/2 phosphorylation and further affected ERK activation, which induced G2/M phase arrest.

Toxic effects of Tripterygium glycoside tablets on the reproductive system of male rats by metabolomics, cytotoxicity, and molecular docking.

BACKGROUND: Tripterygium glycoside tablets (TGT) is the most common preparation from Tripterygium wilfordii Hook F, which is widely used in clinical for treating rheumatoid arthritis (RA) and other autoimmune diseases. However, its serious reproductive toxicity limits its application. PURPOSE: This study aimed to elucidate the toxic effects of TGT on the reproductive system of male RA rats and its potential toxic components and mechanism. METHODS: Collagen-induced arthritis (CIA) rat model was established, and TGT suspension was given at low, medium, and high doses. Gonadal index, pathological changes, and the number of spermatogenic cells were used to evaluate the toxic effects of TGT on the reproductive system. Non-targeted metabolomics of testicular tissue was conducted by UHPLC-QTOF/MS. Combined with network toxicology, the key targets of TGT-induced reproductive toxicity were screened and RT-qPCR was used to validation. In vitro toxicity of 19 components of TGT was evaluated using TM3 and TM4 cell lines. Molecular docking was used to predict the interaction between toxic components and key targets. RESULTS: TGT reduced testicular and epididymis weight. Pathology analysis showed a lot of deformed and atrophic spermatogenic tubules. The number of spermatogenic cells decreased significantly (P<0.0001). A total of 58 different metabolites including platelet-activating factor (PAF), lysophosphatidylcholine (Lyso PC), phosphatidylinositol (PI), glutathione (GSH), and adenosine monophosphate (AMP) were identified by testicular metabolomics. Glycerophospholipid metabolism, ether lipid metabolism, and glutathione metabolism were key pathways responsible for the reproductive toxicity of TGT. Ten key reproductive toxicity targets were screened by network toxicology. The cytotoxicity test showed that triptolide, triptonide, celastrol, and demethylzeylasteral could significantly reduce the viability of TM3 and TM4 cells. Alkaloids had no apparent toxic effects. Molecular docking showed that the four toxic components had a good affinity with 10 key targets. All binding energies were less than -7 kcal/mol. The RT-qPCR results showed the Cyp19a1 level was significantly up-regulated. Pik3ca and Pik3cg levels were significantly down-regulated. CONCLUSION: Through testicular metabolomics, we found that TGT may cause reproductive toxicity through CYP19A1, PIK3CA, and PIK3CG three target, which was preliminarily revealed. This study laid the foundation for elucidating the toxicity mechanism of TGT and evaluating its safety and quality.

Multi-component immune knockout: A strategy for studying the effective components of traditional Chinese medicine.

Periploca forrestii Schltr., a traditional Chinese medicine (TCM), is commonly used to treat autoimmune diseases such as rheumatoid arthritis (RA). However, its mechanism, involving a variety of cardiac glycosides, remains largely unknown. The immune knockout strategy can highly selectively deplete target components by immunoaffinity chromatography (IAC). We aimed to identify the common structural features of cardiac glycosides in P. forrestii and design IAC to specifically recognize these features to achieve the multi-component knockout of potential active substances from the extracts of P. forrestii. A content detection experiment confirmed that the content of a compound with periplogenin structure (CPS) in the extract of P. forrestii was reduced by 45% by IAC of periplogenin. The immunosuppressive ability of the extract on H9 human T lymphocytic cells was weakened after CPS knockout from P. forrestii extract. Molecular biology experiments showed that mRNA expression of interferon-γ (IFN-γ), interleukin-2 (IL-2), and interleukin-6 (IL-6) in H9 cells was up-regulated after CPS knockout, while no significant changes in the expression of interleukin-4 (IL-4) were found. CPS knockout from P. forrestii extract did not cause significant changes in the proliferation of lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells incubated with this extract. These results indicate that CPS exhibited immunosuppressive effects via inhibiting the T helper 1 (Th1) cell immune response and not via the anti-inflammatory components in P. forrestii. This is the first use of IAC to achieve multi-component knockout in TCM extracts for identifying effective compounds. This method is effective and reliable and warrants further exploration.

Localized Microsphere/Hydrogel for Tumor Immunotherapy of Cardiac Glycoside with Minimal Toxicity.

It has been reported that cardiac glycosides (CGs) commonly used in clinical practice can inhibit tumor growth by inducing immunogenic cell death (ICD), and their positive benefits have been documented in several clinical trials of drug combinations. However, the inherent cardiogenic side effects need to be addressed before CGs can be truly applied in clinical antitumor therapy. In this study, a dual controlled release microsphere/hydrogel platform (OL-M/Gel) was constructed to precisely control the output of oleandrin (OL, one of the representative CGs) in situ in tumors. With the help of this intelligent drug release platform, OL can be released in vitro and in vivo in a sustained and stable manner. The ability of OL to induce ICD and the subsequent antigen presentation and cytotoxic T-cell cascades was first stated, which resulted in potent tumor growth suppression without significant side effects. In addition, the inhibition of autologous tumor recurrence and metastasis by OL-M/Gel was also revealed. This study is expected to break through the inherent bottleneck of CGs and promote their clinical transformation in the field of antitumor treatment.

Evaluation of the Sensitivity of Breast Cancer Cell Lines to Cardiac Glycosides Unveils ATP1B3 as a Possible Biomarker for the Personalized Treatment of ERα Expressing Breast Cancers.

The molecular classification of breast cancer (BC) dictates pharmacological treatment. Estrogen receptor α (ERα) expressing tumors are treated with 4OH-tamoxifen or fulvestrant, which inhibits the receptor, or with aromatase inhibitors (i.e., anastrozole, letrozole, and exemestane) that reduce the 17ß-estradiol (E2) circulating blood levels. Besides such endocrine therapy (ET) drugs, ERα-positive BCs can be treated with epidermal growth factor receptor (EGF-R) inhibitors (i.e., gefitinib, erlotinib, and lapatinib) according to HER2 expression. Notwithstanding these anti-BC drugs, novel personalized approaches for BC treatment are required because prolonged administration of those pharmaceutics determines resistant phenotypes, which result in metastatic BC. We have recently reported that the cardiac glycoside (CG) (i.e., Na/K ATPase inhibitor) ouabain could be repurposed for ERα-positive primary and metastatic BC treatment as it induces ERα degradation and kills BC cells. Here, we evaluated if other CGs could represent additional treatment options for ERα-positive BCs and if the Na/K ATPase could be considered a biomarker for ERα-positive BC treatment. The results indicate that the ATP1B3 Na/K ATPase isoform can educate the choice for the personalized treatment of ERα-positive BC with CGs and that CGs could be more efficacious if they are administered in association with gefitinib.

Chemistry and anticancer activity of cardiac glycosides: A review.

The objective of this review is an attempt to emphasize the development in the chemistry and to display review of diverse therapeutic actions of cardiac glycosides. Anticancer activity of cardiac glycosides is the main activity as discussed in this review. The aim of the review is to gather the recent researches on cardiac glycosides. The present manuscript gives the platform for the researcher to have complete literature on the topic.

Repurposing Cardiac Glycosides: Drugs for Heart Failure Surmounting Viruses.

Drug repositioning is a successful approach in medicinal research. It significantly simplifies the long-term process of clinical drug evaluation, since the drug being tested has already been approved for another condition. One example of drug repositioning involves cardiac glycosides (CGs), which have, for a long time, been used in heart medicine. Moreover, it has been known for decades that CGs also have great potential in cancer treatment and, thus, many clinical trials now evaluate their anticancer potential. Interestingly, heart failure and cancer are not the only conditions for which CGs could be effectively used. In recent years, the antiviral potential of CGs has been extensively studied, and with the ongoing SARS-CoV-2 pandemic, this interest in CGs has increased even more. Therefore, here, we present CGs as potent and promising antiviral compounds, which can interfere with almost any steps of the viral life cycle, except for the viral attachment to a host cell. In this review article, we summarize the reported data on this hot topic and discuss the mechanisms of antiviral action of CGs, with reference to the particular viral life cycle phase they interfere with.

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.

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.

Identification of key regulators responsible for dysregulated networks in osteoarthritis by large-scale expression analysis.

BACKGROUND: Osteoarthritis (OA) is a worldwide musculoskeletal disorder. However, disease-modifying therapies for OA are not available. Here, we aimed to characterize the molecular signatures of OA and to identify novel therapeutic targets and strategies to improve the treatment of OA. METHODS: We collected genome-wide transcriptome data performed on 132 OA and 74 normal human cartilage or synovium tissues from 7 independent datasets. Differential gene expression analysis and functional enrichment were performed to identify genes and pathways that were dysregulated in OA. The computational drug repurposing method was used to uncover drugs that could be repurposed to treat OA. RESULTS: We identified several pathways associated with the development of OA, such as extracellular matrix organization, inflammation, bone development, and ossification. By protein-protein interaction (PPI) network analysis, we prioritized several hub genes, such as JUN, CDKN1A, VEGFA, and FOXO3. Moreover, we repurposed several FDA-approved drugs, such as cardiac glycosides, that could be used in the treatment of OA. CONCLUSIONS: We proposed that the hub genes we identified would play a role in cartilage homeostasis and could be important diagnostic and therapeutic targets. Drugs such as cardiac glycosides provided new possibilities for the treatment of OA.

Oleandrin, a cardiac glycoside, induces immunogenic cell death via the PERK/elF2α/ATF4/CHOP pathway in breast cancer.

Chemotherapeutic agents have been linked to immunogenic cell death (ICD) induction that is capable of augmenting anti-tumor immune surveillance. The cardiac glycoside oleandrin, which inhibits Na+/K+-ATPase pump (NKP), has been shown to suppress breast cancer growth via inducing apoptosis. In the present study, we showed that oleandrin treatment triggered breast cancer cell ICD by inducing calreticulin (CRT) exposure on cell surface and the release of high-mobility group protein B1 (HMGB1), heat shock protein 70/90 (HSP70/90), and adenosine triphosphate (ATP). The maturation and activation of dendritic cells (DCs) were increased by co-culturing with the oleandrin-treated cancer cells, which subsequently enhanced CD8+ T cell cytotoxicity. Murine breast cancer cell line EMT6 was engrafted into BALB/c mice, and tumor-bearing mice were administered with oleandrin intraperitoneally every day. Oleandrin inhibited tumor growth and increased tumor infiltrating lymphocytes including DCs and T cells. Furthermore, the differential mRNA expression incurred by oleandrin was investigated by mRNA sequencing and subsequently confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Mechanistically, oleandrin induced endoplasmic reticulum (ER) stress-associated, caspase-independent ICD mainly through PERK/elF2α/ATF4/CHOP pathway. Pharmacological and genetic inhibition of protein kinase R-like ER kinase (PERK) suppressed oleandrin-triggered ICD. Taken together, our findings showed that oleandrin triggered ER stress and induced ICD-mediated immune destruction of breast cancer cells. Oleandrin combined with immune checkpoint inhibitors might improve the efficacy of immunotherapy.

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.

Cardiac glycosides inhibit cancer through Na/K-ATPase-dependent cell death induction.

Successful drug repurposing relies on the understanding of molecular mechanisms of the target compound. Cardiac glycosides have demonstrated potent anticancer activities; however, the pharmacological mechanisms underlying their anticancer effects remained elusive, which has restricted their further development in cancer treatment. A bottleneck is the lack of comprehensive understanding about genes and signaling pathways that are altered at the early stage of drug treatment, which is key to understand how they inhibit cancer. To address this issue, we first investigated the anticancer effects of a panel of 68 naturally isolated cardiac glycosides. Our results illustrate critical structure activity relationship of these compounds on cancer cell survival. We confirmed the anticancer effect of cardiac glycoside in mouse tumor xenografts. Through RNA sequencing, quantitative PCR and immunoblotting, we show that cardiac glycoside first activated autophagy and then induced apoptosis. Further activating autophagy by rapamycin or inhibiting apoptosis by caspase inhibitor mitigated cardiac glycoside-induced cell death, whereas inhibiting autophagy by RNA interference-mediated depletion of critical autophagy genes enhanced cell death. While depletion of Na/K-ATPase, the protein target of cardiac glycosides, by RNA interference inhibited both autophagy activation and apoptosis induction by cardiac glycoside, expression of human, but not rodent Na/K-ATPase, increased cell sensitivity to cardiac glycoside. In conclusion, our analyses reveal sequential activation of autophagy and apoptosis during early stages of cardiac glycoside treatment and indicate the importance of Na/K-ATPase in their anticancer effects.

Design and Synthesis of Polymer Prodrugs for Improving Water-Solubility, Pharmacokinetic Behavior and Antitumor Efficacy of TXA9.

PURPOSE: TXA9, a novel cardiac glycoside, has a potent anti-proliferative effect against A549 human lung cancer cells, however, possesses a poor water-solubility and a rapid metabolic rate in vivo which limited the further development of TXA9. To overcome the shortcomings of TXA9, four polymer prodrugs of TXA9 were designed and synthesized. METHODS: Poly (ethylene glycol) monomethyl ether (mPEG) and α-tocopherol polyethylene glycol succinate (TPGS) were applied to modify TXA9 via carbonate ester and glycine linkers respectively to obtain four polymer prodrugs. The water-solubility and stability of prodrugs were studied in vitro while their pharmacokinetic behaviors and antitumor activity were investigated in vivo. RESULTS: The water-solubility of TXA9 was obviously increased and prodrugs with glycine linkers showed a better stability in rat plasma. Their pharmacokinetic investigation found that the t1/2 and AUC0-∞ of TPGS-Gly-TXA9 was increased by 80- and 9.6-fold compared with that of TXA9, which was more superior than the other three prodrugs. More importantly, the tumor inhibition rate of TPGS-Gly-TXA9 (43.81%) on A549 xenograft nude mice was significantly increased compared with that of TXA9 (25.26%). CONCLUSION: The above results suggested that TPGS-Gly-TXA9 possessed better antitumor efficiency than TXA9 and could be further investigated as an anti-cancer agent.

Repurposing of drugs approved for cardiovascular diseases: Opportunity or mirage?

Drug repurposing is a promising way in drug discovery to identify new therapeutic uses -different from the original medical indication- for existing drugs. It has many advantages over traditional approaches to de novo drug discovery, since it can significantly reduce healthcare costs and development timeline. In this review, we discuss the possible repurposing of drugs approved for cardiovascular diseases, such as ß-blockers, angiotensin converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), statins, aspirin, cardiac glycosides and low-molecular-weight heparins (LMWHs). Indeed, numerous experimental and epidemiological studies have reported promising anti-cancer activities for these drugs. It is worth mentioning, however, that the results of these studies are often controversial and very few data were obtained by controlled prospective clinical trials. Therefore, no final conclusion has yet been reached in this area and no final recommendations can be made. Moreover, ß-blockers, ARBs and statins showed promising results in randomised controlled trials (RCTs) where pathological conditions other than cancer were considered. The results obtained have led or may lead to new indications for these drugs. For each drug or class of drugs, the potential molecular mechanisms of action justifying repurposing, results obtained in vitro and in animal models and data from epidemiological and randomized studies are described.

The Redox-Sensitive Na/K-ATPase Signaling in Uremic Cardiomyopathy.

In recent years, Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions, including cardiac hypertrophy and uremic cardiomyopathy. Cardiotonic steroids (CTS), specific ligands of Na/K-ATPase, regulate its enzymatic activity (at higher concentrations) and signaling function (at lower concentrations without significantly affecting its enzymatic activity) and increase reactive oxygen species (ROS) generation. On the other hand, an increase in ROS alone also regulates the Na/K-ATPase enzymatic activity and signaling function. We termed this phenomenon the Na/K-ATPase-mediated oxidant-amplification loop, in which oxidative stress regulates both the Na/K-ATPase activity and signaling. Most recently, we also demonstrated that this amplification loop is involved in the development of uremic cardiomyopathy. This review aims to evaluate the redox-sensitive Na/K-ATPase-mediated oxidant amplification loop and uremic cardiomyopathy.