Drug Repurposing of the Anthelmintic Niclosamide to Treat Multidrug-Resistant Leukemia

Neuroprotective effects of niclosamide on disease progression via inflammatory pathways modulation in SOD1-G93A and FUS-associated amyotrophic lateral sclerosis models

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease influenced by genetic, epigenetic, and environmental factors, resulting in dysfunction in cellular and molecular pathways. The limited efficacy of current treatments highlights the need for combination therapies targeting multiple aspects of the disease. Niclosamide, an anthelminthic drug listed as an essential medicine, has been repurposed in clinical trials for different diseases due to its anti-inflammatory and anti-fibrotic properties. Niclosamide can inhibit various molecular pathways (e.g., STAT3, mTOR) that are dysregulated in ALS, suggesting its potential to disrupt these altered mechanisms associated with the pathology. We administered niclosamide intraperitoneally to two transgenic murine models, SOD1-G93A and FUS mice, mimicking key pathological processes of ALS. The treatment was initiated at the onset of symptoms, and we assessed disease progression by neurological scores, rotarod and wire tests, and monitored survival. Furthermore, we investigated cellular and molecular mechanisms affected by niclosamide in the spinal cord and muscle of ALS mice. In both models, the administration of niclosamide resulted in a slowdown of disease progression, an increase in survival rates, and an improvement in tissue pathology. This was characterised by reduced gliosis, motor neuron loss, muscle atrophy, and inflammatory pathways. Based on these results, our findings demonstrate that niclosamide can impact multiple pathways involved in ALS. This multi-targeted approach leads to a slowdown in the progression of the disease, positioning niclosamide as a promising candidate for repurposing in the treatment of ALS.

Differences in the transcriptome response in the gills of sea lamprey acutely exposed to 3-trifluoromethyl-4-nitrophenol (TFM), niclosamide or a TFM:niclosamide mixture

Sea lamprey (Petromyzon marinus) control in the Laurentian Great Lakes of North America makes use of two pesticides: 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide, which are often co-applied. Sea lamprey appear to be vulnerable to these agents resulting from a lack of detoxification responses with evidence suggesting that lampricide mixtures produce a synergistic effect. However, there is a lack of information pertaining to the physiological responses of sea lamprey to niclosamide and TFM:niclosamide mixtures. Here, we characterized the transcriptomic responses of the sea lamprey to TFM, niclosamide, and a TFM:niclosamide (1.5 %) mixture in the gill. Along with a control, larval sea lamprey were exposed to each treatment for 6 h, after which gill tissues were extracted for measuring whole-transcriptome responses using RNA sequencing. Differential gene expression patterns were summarized, which included identifying the broad roles of genes and common expression patterns among the treatments. While niclosamide treatment resulted in no differentially expressed genes, TFM- and mixture-treated fish had several differentially expressed genes that were associated with the cell cycle, DNA damage, metabolism, immune function, and detoxification. However, there was no common differential expression among treatments. For the first time, we characterized the transcriptomic response of sea lamprey to niclosamide and a TFM:niclosamide mixture and identified that these agents impact mRNA transcript abundance of genes associated with the cell cycle and cellular death, and immune function, which are likely mediated through mitochondrial dysregulation. These results may help to inform the production of more targeted and effective lampricides in sea lamprey control efforts.

Metabolomic analyses uncover an inhibitory effect of niclosamide on mitochondrial membrane potential in cholangiocarcinoma cells

Background

Niclosamide is an oral anthelminthic drug that has been used for treating tapeworm infections. Its mechanism involves the disturbance of mitochondrial membrane potential that in turn inhibits oxidative phosphorylation leading to ATP depletion. To date, niclosamide has been validated as the potent anti-cancer agent against several cancers. However, the molecular mechanisms underlying the effects of niclosamide on the liver fluke Opisthorchis viverrini (Ov)-associated cholangiocarcinoma (CCA) cell functions remain to be elucidated. The aims of this study were to investigate the effects of niclosamide on CCA cell proliferation and on metabolic phenoconversion through the alteration of metabolites associated with mitochondrial function in CCA cell lines.

Materials and Methods

The inhibitory effect of niclosamide on CCA cells was determined using SRB assay. A mitochondrial membrane potential using tetramethylrhodamine, ethyl ester-mitochondrial membrane potential (TMRE-MMP) assay was conducted. Liquid chromatography-mass spectrometry-based metabolomics was employed to investigate the global metabolic changes upon niclosamide treatment. ATP levels were measured using CellTiter-Glo® luminescent cell viability assay. NAD metabolism was examined by the NAD+/NADH ratio.

Results

Niclosamide strongly inhibited CCA cell growth and reduced the MMP of CCA cells. An orthogonal partial-least square regression analysis revealed that the effects of niclosamide on suppressing cell viability and MMP of CCA cells were significantly associated with an increase in niacinamide, a precursor in NAD synthesis that may disrupt the electron transport system leading to suppression of NAD+/NADH ratio and ATP depletion.

Conclusion

Our findings unravel the mode of action of niclosamide in the energy depletion that could potentially serve as the promising therapeutic strategy for CCA treatment.

Niclosamide inhibits epithelial-mesenchymal transition with apoptosis induction in BRAF/ NRAS mutated metastatic melanoma cells

Malignant melanoma is considered a deadly aggressive form of skin cancer that frequently metastasizes to various distal organs, which harbors mutations of the BRAF or NRAS which occur in 30 to 50% of melanoma patients. The growth factors secreted by melanoma cells contribute to tumor angiogenesis with the acquisition of metastatic potential by epithelial-mesenchymal transition (EMT) and drive melanoma growth toward a more aggressive form. Niclosamide (NCL) is an FDA-approved anthelmintic drug and is reported to have strong anti-cancer properties against various solid and liquid tumors. Its role in BRAF or NRAS mutated cells is unknown. In this context, we uncovered the role of NCL in impeding malignant metastatic melanoma in vitro in SK-MEL-2 and SK-MEL-28 cell lines. We found that NCL induces significant ROS generation and apoptosis through a series of molecular mechanisms, such as depolarization of mitochondrial membrane potential, arresting the cell cycle at the sub G1 phase with a significant increase in the DNA cleavage via topoisomerase II in both cell lines. We also found that NCL potently inhibited metastasis, which was examined by scratch wound assay, Additionally, we found that NCL inhibits the most important markers involved in the EMT signaling cascade that are stimulated by TGF-β such as N-cadherin, Snail, Slug, Vimentin, α-SMA and p-Smad 2/3. This work provides useful insights into the mechanism of NCL in BRAF/NRAF mutant melanoma cells via inhibition of molecular signaling events involved in EMT signaling, and apoptosis induction.

Drug Repurposing: An Effective Tool in Modern Drug Discovery

Drug repurposing is using an existing drug for a new treatment that was not indicated before. It has received immense attention during the COVID-19 pandemic emergency. Drug repurposing has become the need of time to fasten the drug discovery process and find quicker solutions to the over-exerted healthcare scenario and drug needs. Drug repurposing involves identifying the drug, evaluating its efficiency using preclinical models, and proceeding to phase II clinical trials. Identification of the drug candidate can be made through computational and experimental approaches. This approach usually utilizes public databases for drugs. Data from primary and translational research, clinical trials, anecdotal reports regarding off-label uses, and other published human data information available are included. Using artificial intelligence algorithms and other bioinformatics tools, investigators systematically try to identify the interaction between drugs and protein targets. It can be combined with genetic data, clinical analysis, structure (molecular docking), pathways, signatures, targets, phenotypes, binding assays, and artificial intelligence to get an optimum outcome in repurposing. This article describes the strategies involved in drug repurposing and enlists a series of repurposed drugs and their indications.

Application of Drug Repurposing-Based Precision Medicine Platform for Leukaemia Patient Treatment

Drug resistance in leukaemia is a major problem that needs to be addressed. Precision medicine provides an avenue to reduce drug resistance through a personalised treatment plan. It has helped to better stratify patients based on their molecular profile and therefore improved the sensitivity of patients to a given therapeutic regimen. However, therapeutic options are still limited for patients who have already been subjected to many lines of chemotherapy. The process of designing and developing new drugs requires significant resources, including money and time. Drug repurposing has been explored as an alternative to identify effective drug(s) that could be used to target leukaemia and lessen the burden of drug resistance. The drug repurposing process usually includes preclinical studies with drug screening and clinical trials before approval. Although most of the repurposed drugs that have been identified are generally safe for leukaemia treatment, they seem not to be good candidates for monotherapy but could have value in combination with other drugs, especially for patients who have exhausted therapeutic options. In this review, we highlight precision medicine in leukaemia and the role of drug repurposing. Specifically, we discuss the several screening methods via chemoinformatic, in vitro, and ex vivo that have facilitated and accelerated the drug repurposing process.

Niclosamide as a Promising Therapeutic Player in Human Cancer and Other Diseases

Niclosamide is an FDA-approved anthelmintic drug for the treatment of parasitic infections. However, over the past few years, increasing evidence has shown that niclosamide could treat diseases beyond parasitic diseases, which include metabolic diseases, immune system diseases, bacterial and viral infections, asthma, arterial constriction, myopia, and cancer. Therefore, we systematically reviewed the pharmacological activities and therapeutic prospects of niclosamide in human disease and cancer and summarized the related molecular mechanisms and signaling pathways, indicating that niclosamide is a promising therapeutic player in various human diseases, including cancer.

Variation in the Transcriptome Response and Detoxification Gene Diversity Drives Pesticide Tolerance in Fishes

Pesticides are critical for invasive species management but often have negative effects on nontarget native biota. Tolerance to pesticides should have an evolutionary basis, but this is poorly understood. Invasive sea lamprey (Petromyzon marinus) populations in North America have been controlled with a pesticide lethal to them at lower concentrations than native fishes. We addressed how interspecific variation in gene expression and detoxification gene diversity confer differential pesticide sensitivity in two fish species. We exposed sea lamprey and bluegill (Lepomis macrochirus), a tolerant native species, to 3-trifluoromethyl-4-nitrophenol (TFM), a pesticide commonly used in sea lamprey control. We then used whole-transcriptome sequencing of gill and liver to characterize the cellular response in both species. Comparatively, bluegill exhibited a larger number of detoxification genes expressed and a larger number of responsive transcripts overall, which likely contributes to greater tolerance to TFM. Understanding the genetic and physiological basis for pesticide tolerance is crucial for managing invasive species.

In Vitro Evaluation and Mitigation of Niclosamide's Liabilities as a COVID-19 Treatment

Niclosamide, an FDA-approved oral anthelmintic drug, has broad biological activity including anticancer, antibacterial, and antiviral properties. Niclosamide has also been identified as a potent inhibitor of SARS-CoV-2 infection in vitro, generating interest in its use for the treatment or prevention of COVID-19. Unfortunately, there are several potential issues with using niclosamide for COVID-19, including low bioavailability, significant polypharmacology, high cellular toxicity, and unknown efficacy against emerging SARS-CoV-2 variants of concern. In this study, we used high-content imaging-based immunofluorescence assays in two different cell models to assess these limitations and evaluate the potential for using niclosamide as a COVID-19 antiviral. We show that despite promising preliminary reports, the antiviral efficacy of niclosamide overlaps with its cytotoxicity giving it a poor in vitro selectivity index for anti-SARS-CoV-2 inhibition. We also show that niclosamide has significantly variable potency against the different SARS-CoV-2 variants of concern and is most potent against variants with enhanced cell-to-cell spread including the B.1.1.7 (alpha) variant. Finally, we report the activity of 33 niclosamide analogs, several of which have reduced cytotoxicity and increased potency relative to niclosamide. A preliminary structure-activity relationship analysis reveals dependence on a protonophore for antiviral efficacy, which implicates nonspecific endolysosomal neutralization as a dominant mechanism of action. Further single-cell morphological profiling suggests niclosamide also inhibits viral entry and cell-to-cell spread by syncytia. Altogether, our results suggest that niclosamide is not an ideal candidate for the treatment of COVID-19, but that there is potential for developing improved analogs with higher clinical translational potential in the future.

A Niclosamide-releasing hot-melt extruded catheter prevents Staphylococcus aureus experimental biomaterial-associated infection

Biomaterial-associated infections are a major healthcare challenge as they are responsible for high disease burden in critically ill patients. In this study, we have developed drug-eluting antibacterial catheters to prevent catheter-related infections. Niclosamide (NIC), originally an antiparasitic drug, was incorporated into the polymeric matrix of thermoplastic polyurethane (TPU) via solvent casting, and catheters were fabricated using hot-melt extrusion technology. The mechanical and physicochemical properties of TPU polymers loaded with NIC were studied. NIC was released in a sustained manner from the catheters and exhibited in vitro antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis. Moreover, the antibacterial efficacy of NIC-loaded catheters was validated in an in vivo biomaterial-associated infection model using a methicillin-susceptible and methicillin-resistant strain of S. aureus. The released NIC from the produced catheters reduced bacterial colonization of the catheter as well as of the surrounding tissue. In summary, the NIC-releasing hot-melt extruded catheters prevented implant colonization and reduced the bacterial colonization of peri-catheter tissue by methicillin sensitive as well as resistant S. aureus in a biomaterial-associated infection mouse model and has good prospects for preclinical development.

In Vitro Evaluation and Mitigation of Niclosamide’s Liabilities as a COVID-19 Treatment.. [PMID: 35860224 PMCID: PMC9298134 DOI: 10.1101/2022.06.24.497526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Niclosamide, an FDA-approved oral anthelmintic drug, has broad biological activity including anticancer, antibacterial, and antiviral properties. Niclosamide has also been identified as a potent inhibitor of SARS-CoV-2 infection in vitro, generating interest in its use for the treatment or prevention of COVID-19. Unfortunately, there are several potential issues with using niclosamide for COVID-19, including low bioavailability, significant polypharmacology, high cellular toxicity, and unknown efficacy against emerging SARS-CoV-2 variants of concern. In this study, we used high-content imaging-based immunofluorescence assays in two different cell models to assess these limitations and evaluate the potential for using niclosamide as a COVID-19 antiviral. We show that despite promising preliminary reports, the antiviral efficacy of niclosamide overlaps with its cytotoxicity giving it a poor in vitro selectivity index for anti-SARS-CoV-2 inhibition. We also show that niclosamide has significantly variable potency against the different SARS-CoV-2 variants of concern and is most potent against variants with enhanced cell-to-cell spread including B.1.1.7. Finally, we report the activity of 33 niclosamide analogs, several of which have reduced cytotoxicity and increased potency relative to niclosamide. A preliminary structure-activity relationship analysis reveals dependence on a protonophore for antiviral efficacy, which implicates nonspecific endolysosomal neutralization as a dominant mechanism of action. Further single-cell morphological profiling suggests niclosamide also inhibits viral entry and cell-to-cell spread by syncytia. Altogether, our results suggest that niclosamide is not an ideal candidate for the treatment of COVID-19, but that there is potential for developing improved analogs with higher clinical translational potential in the future.

Niclosamide - a promising treatment for COVID-19

Vaccines have reduced the transmission and severity of COVID‐19, but there remains a paucity of efficacious treatment for drug‐resistant strains and more susceptible individuals, particularly those who mount a suboptimal vaccine response, either due to underlying health conditions or concomitant therapies. Repurposing existing drugs is a timely, safe and scientifically robust method for treating pandemics, such as COVID‐19. Here, we review the pharmacology and scientific rationale for repurposing niclosamide, an anti‐helminth already in human use as a treatment for COVID‐19. In addition, its potent antiviral activity, niclosamide has shown pleiotropic anti‐inflammatory, antibacterial, bronchodilatory and anticancer effects in numerous preclinical and early clinical studies. The advantages and rationale for nebulized and intranasal formulations of niclosamide, which target the site of the primary infection in COVID‐19, are reviewed. Finally, we give an overview of ongoing clinical trials investigating niclosamide as a promising candidate against SARS‐CoV‐2.

Anti-cancer potential of some commonly used drugs

Cancer is a global concern leading to millions of deaths every year. A declining trend in new drug discovery and development is becoming one of the major issues among the pharmaceutical, biotechnology industries, and regulatory agencies. New drug development is proven to be a very lengthy and costly process. The launch of a new drug takes 8-12 years and huge investments. The success rate in oncology therapeutics is also low due to toxicities at the pre-clinical and clinical trial levels. Many oncological drugs get rejected at a very promising stage, showing adverse reactions on healthy cells. Thus, exploring new therapeutic benefits of the existing, shelved drugs for their anti-cancerous action could result in a therapeutic approach preventing the toxicities which occur during clinical trials. Drug repurposing has the potential to overcome the challenges faced via conventional way of drug discovery and is becoming an area of interest for researchers and scientists. However, very few in vivo studies are conducted to prove the anti-cancerous activity of the drugs. Insufficient in vivo animal studies and a lack of human clinical trials are the lacunae in the field of drug repurposing. This review focuses on an aspect of drug repurposing for cancer therapeutics. Various studies that show that drugs approved for clinical indications other than cancer have shown promising anti-cancer activities. Some of the commonly used drugs like Benzodiazepines (Diazepam, Midzolam), Antidepressants (Imipramine, Clomipramine, and Citalopram), Antiepileptic (Valporic acid, Phenytoin), Antidiabetics (metformin), etc. have been reported to show potential activity against the cancerous cells.

Targeting S100A4 with niclosamide attenuates inflammatory and profibrotic pathways in models of amyotrophic lateral sclerosis

Background

An increasing number of studies evidences that amyotrophic lateral sclerosis (ALS) is characterized by extensive alterations in different cell types and in different regions besides the CNS. We previously reported the upregulation in ALS models of a gene called fibroblast-specific protein-1 or S100A4, recognized as a pro-inflammatory and profibrotic factor. Since inflammation and fibrosis are often mutual-sustaining events that contribute to establish a hostile environment for organ functions, the comprehension of the elements responsible for these interconnected pathways is crucial to disclose novel aspects involved in ALS pathology.

Methods

Here, we employed fibroblasts derived from ALS patients harboring the C9orf72 hexanucleotide repeat expansion and ALS patients with no mutations in known ALS-associated genes and we downregulated S100A4 using siRNA or the S100A4 transcriptional inhibitor niclosamide. Mice overexpressing human FUS were adopted to assess the effects of niclosamide in vivo on ALS pathology.

Results

We demonstrated that S100A4 underlies impaired autophagy and a profibrotic phenotype, which characterize ALS fibroblasts. Indeed, its inhibition reduces inflammatory, autophagic, and profibrotic pathways in ALS fibroblasts, and interferes with different markers known as pathogenic in the disease, such as mTOR, SQSTM1/p62, STAT3, α-SMA, and NF-κB. Importantly, niclosamide in vivo treatment of ALS-FUS mice reduces the expression of S100A4, α-SMA, and PDGFRβ in the spinal cord, as well as gliosis in central and peripheral nervous tissues, together with axonal impairment and displays beneficial effects on muscle atrophy, by promoting muscle regeneration and reducing fibrosis.

Conclusion

Our findings show that S100A4 has a role in ALS-related mechanisms, and that drugs such as niclosamide which are able to target inflammatory and fibrotic pathways could represent promising pharmacological tools for ALS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02184-1.

Development of Thiabendazole-Loaded Mesoporous Silica Nanoparticles for Cancer Therapy

Thiabendazole (TBZ) is an anthelmintic drug currently studied for anticancer purposes. However, due to its low solubility, its biomedical application has been limited. Using mesoporous silica nanoparticles (MSNPs), such as Mobil Composition of Matter Number 41 (MCM-41), as a drug carrier, is a promising approach to improve the solubility of low water-soluble drugs. In the present work, we aim to develop TBZ-loaded MCM-41 (TBZ MCM-41) nanoparticles to improve the solubility and the therapeutic efficacy of TBZ against prostate cancer PC-3 cells. TBZ MCM-41 nanoparticles were synthesized with a size of 215.9 ± 0.07 nm, a spherical shape, a hexagonal array of channels, and a drug loading capacity of 19.1%. The biological effects of the nanoformulation on PC-3 cells were then evaluated using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT), IncuCyte live-cell imaging system, cell migration, and reactive oxygen species (ROS) assays. The results demonstrated that TBZ was released from MCM-41 nanoparticles in a controlled manner at pH values of 1.2 and 6.8. The cell viability measurements revealed that the TBZ MCM-41 nanoparticles caused a considerable 2.8-fold increase in the cytotoxicity of TBZ (IC₅₀ 127.3 and 46 μM for TBZ and TBZ MCM-41 nanoparticles, respectively). The results of the proliferation assay were in agreement with those of the cell viability measurements, where the MCM-41 increased the cytotoxicity of TBZ in a concentration-dependent manner. Also, the TBZ MCM-41 nanoparticles were found to enhance the potency of the drug and inhibit PC-3 cell migration. In addition, the ROS assay confirmed that TBZ MCM-41 nanoparticles were approximately 15% more potent than TBZ to produce ROS. Overall, the results demonstrated that MCM-41 nanoparticles are a promising carrier to improve the therapeutic efficacy of TBZ against PC-3 cells and suggest evaluating the efficacy of the formulation in vivo.

Overcoming Glucocorticoid Resistance in Acute Lymphoblastic Leukemia: Repurposed Drugs Can Improve the Protocol

Glucocorticoids (GCs) are a central component of multi-drug treatment protocols against T and B acute lymphoblastic leukemia (ALL), which are used intensively during the remission induction to rapidly eliminate the leukemic blasts. The primary response to GCs predicts the overall response to treatment and clinical outcome. In this review, we have critically analyzed the available data on the effects of GCs on sensitive and resistant leukemic cells, in order to reveal the mechanisms of GC resistance and how these mechanisms may determine a poor outcome in ALL. Apart of the GC resistance, associated with a decreased expression of receptors to GCs, there are several additional mechanisms, triggered by alterations of different signaling pathways, which cause the metabolic reprogramming, with an enhanced level of glycolysis and oxidative phosphorylation, apoptosis resistance, and multidrug resistance. Due to all this, the GC-resistant ALL show a poor sensitivity to conventional chemotherapeutic protocols. We propose pharmacological strategies that can trigger alternative intracellular pathways to revert or overcome GC resistance. Specifically, we focused our search on drugs, which are already approved for treatment of other diseases and demonstrated anti-ALL effects in experimental pre-clinical models. Among them are some “truly” re-purposed drugs, which have different targets in ALL as compared to other diseases: cannabidiol, which targets mitochondria and causes the mitochondrial permeability transition-driven necrosis, tamoxifen, which induces autophagy and cell death, and reverts GC resistance through the mechanisms independent of nuclear estrogen receptors (“off-target effects”), antibiotic tigecycline, which inhibits mitochondrial respiration, causing energy crisis and cell death, and some anthelmintic drugs. Additionally, we have listed compounds that show a classical mechanism of action in ALL but are not used still in treatment protocols: the BH3 mimetic venetoclax, which inhibits the anti-apoptotic protein Bcl-2, the hypomethylating agent 5-azacytidine, which restores the expression of the pro-apoptotic BIM, and compounds targeting the PI3K-Akt-mTOR axis. Accordingly, these drugs may be considered for the inclusion into chemotherapeutic protocols for GC-resistant ALL treatments.

Drug repurposing using transcriptome sequencing and virtual drug screening in a patient with glioblastoma

Background Precision medicine and drug repurposing are attractive strategies, especially for tumors with worse prognosis. Glioblastoma is a highly malignant brain tumor with limited treatment options and short survival times. We identified novel BRAF (47-438del) and PIK3R1 (G376R) mutations in a glioblastoma patient by RNA-sequencing. Methods The protein expression of BRAF and PIK3R1 as well as the lack of EGFR expression as analyzed by immunohistochemistry corroborated RNA-sequencing data. The expression of additional markers (AKT, SRC, mTOR, NF-κB, Ki-67) emphasized the aggressiveness of the tumor. Then, we screened a chemical library of > 1500 FDA-approved drugs and > 25,000 novel compounds in the ZINC database to find established drugs targeting BRAF47-438del and PIK3R1-G376R mutated proteins. Results Several compounds (including anthracyclines) bound with higher affinities than the control drugs (sorafenib and vemurafenib for BRAF and PI-103 and LY-294,002 for PIK3R1). Subsequent cytotoxicity analyses showed that anthracyclines might be suitable drug candidates. Aclarubicin revealed higher cytotoxicity than both sorafenib and vemurafenib, whereas idarubicin and daunorubicin revealed higher cytotoxicity than LY-294,002. Liposomal formulations of anthracyclines may be suitable to cross the blood brain barrier. Conclusions In conclusion, we identified novel small molecules via a drug repurposing approach that could be effectively used for personalized glioblastoma therapy especially for patients carrying BRAF47-438del and PIK3R1-G376R mutations.

Identification and characterization of deschloro-chlorothricin obtained from a large natural product library targeting aurora A kinase in multiple myeloma

Multiple myeloma (MM) is a devastating disease with low survival rates worldwide. The mean lifetime of patients may be extendable with new drug alternatives. Aurora A kinase (AURKA) is crucial in oncogenesis, because its overexpression or amplification may incline the development of various types of cancer, including MM. Therefore, inhibitors of AURKA are innovative and promising targets. Natural compounds always represented a valuable resource for anticancer drug development. In the present study, based on virtual drug screening of more than 48,000 natural compounds, the antibiotic deschloro-chlorotricin (DCCT) has been identified to bind to AURKA with even higher binding affinity (free bindung energy: −12.25 kcal/mol) than the known AURKA inhibitor, alisertib (free binding energy: −11.25 kcal/mol). The in silico studies have been verified in vitro by using microscale thermophoresis. DCCT inhibited MM cell lines (KMS-11, L-363, RPMI-8226, MOLP-8, OPM-2, NCI-H929) with IC₅₀ values in a range from 0.01 to 0.12 μM. Furthermore, DCCT downregulated AURKA protein expression, induced G2/M cell cycle arrest and disturbed the cellular microtubule network as determined by Western blotting, flow cytometry, and fluorescence microscopy. Thus, DCCT may be a promising lead structure for further derivatization and the development of specific AURKA inhibitors in MM therapy.

Repurposing old drugs to fight multidrug resistant cancers

Overcoming multidrug resistance represents a major challenge for cancer treatment. In the search for new chemotherapeutics to treat malignant diseases, drug repurposing gained a tremendous interest during the past years. Repositioning candidates have often emerged through several stages of clinical drug development, and may even be marketed, thus attracting the attention and interest of pharmaceutical companies as well as regulatory agencies. Typically, drug repositioning has been serendipitous, using undesired side effects of small molecule drugs to exploit new disease indications. As bioinformatics gain increasing popularity as an integral component of drug discovery, more rational approaches are needed. Herein, we show some practical examples of in silico approaches such as pharmacophore modelling, as well as pharmacophore- and docking-based virtual screening for a fast and cost-effective repurposing of small molecule drugs against multidrug resistant cancers. We provide a timely and comprehensive overview of compounds with considerable potential to be repositioned for cancer therapeutics. These drugs are from diverse chemotherapeutic classes. We emphasize the scope and limitations of anthelmintics, antibiotics, antifungals, antivirals, antimalarials, antihypertensives, psychopharmaceuticals and antidiabetics that have shown extensive immunomodulatory, antiproliferative, pro-apoptotic, and antimetastatic potential. These drugs, either used alone or in combination with existing anticancer chemotherapeutics, represent strong candidates to prevent or overcome drug resistance. We particularly focus on outcomes and future perspectives of drug repositioning for the treatment of multidrug resistant tumors and discuss current possibilities and limitations of preclinical and clinical investigations.

Identification of Drug Candidates for Breast Cancer Therapy Through Scaffold Repurposing: A Brief Review

Conventional drug discovery is a time consuming and expensive expedition with less clinical preference achievement proportion intended for breast cancer therapy. Even if numerous novel approaches to the conformation of drugs have been introduced for breast cancer therapy, they are yet to be implemented in clinical practice. This tempting strategy facilitates a remarkable chance to take the entire benefit of existing drugs. Despite drug repurposing significantly decrease the investigational period and cost, it has got many objections and issues. Scaffold repurposing is an approach that procures a novel significance on the decrepit motto of "to commencement with a pristine drug" . Hence, we move into a probable and nearer approach, the exploitation of scaffolds, which was originally developed for other purposes, including anti-tumor activity. In this review, we summarize different drugs and scaffolds used in breast cancer therapy.

Vitamin K3 chloro derivative (VKT-2) inhibits HDAC6, activates autophagy and apoptosis, and inhibits aggresome formation in hepatocellular carcinoma cells

Epigenetics plays a vital role in regulating gene expression and determining the specific phenotypes of eukaryotic cells. Histone deacetylases (HDACs) are important epigenetic regulatory proteins effecting multiple biological functions. Particularly, HDAC6 has become a promising anti-cancer drug target because of its regulation of cell mobility, protein trafficking, degradation of misfolded proteins, cell growth, apoptosis, and metastasis. In this study, we identified one out of six vitamin K₃ derivatives, VKT-2, as HDAC6 inhibitor using molecular docking and cell viability assays in HDAC6-overexpressing HuH-7 cancer cells. Microscale thermophoresis and HDAC6 enzymatic assays revealed that VKT-2 bound to HDAC6 and inhibited its function. We further identified its cytotoxic activity. VKT-2 hyperacetylated HDAC6 substrates and disturbed tubulin integrity leading to significant inhibition of tumor migration in both HuH-7 spheroids and U2OS-GFP-α-tubulin cells. Moreover, VKT-2 induced autophagic and apoptotic cell death in HuH-7, while aggresome formation was restrained after VKT-2 treatment. A HuH-7 cell-xenograft model in zebrafish larvae provided evidence that VKT-2 inhibited the tumor growth in vivo. To best of our knowledge, it is the first time to demonstrate that vitamin k₃ derivatives (VKT-2) inhibits HDAC6 in solid tumor cells. These unique findings suggested that VKT-2 is a promising anti-cancer agent targeting HDAC6.

Computational Drug Repositioning: Current Progress and Challenges

Novel drug discovery is time-consuming, costly, and a high-investment process due to the high attrition rate. Therefore, many trials are conducted to reuse existing drugs to treat pressing conditions and diseases, since their safety profiles and pharmacokinetics are already available. Drug repositioning is a strategy to identify a new indication of existing or already approved drugs, beyond the scope of their original use. Various computational and experimental approaches to incorporate available resources have been suggested for gaining a better understanding of disease mechanisms and the identification of repurposed drug candidates for personalized pharmacotherapy. In this review, we introduce publicly available databases for drug repositioning and summarize the approaches taken for drug repositioning. We also highlight and compare their characteristics and challenges, which should be addressed for the future realization of drug repositioning.

Molecular docking-based virtual drug screening revealing an oxofluorenyl benzamide and a bromonaphthalene sulfonamido hydroxybenzoic acid as HDAC6 inhibitors with cytotoxicity against leukemia cells

HDAC6 is a crucial epigenetic modifier that plays a vital role in tumor progression and carcinogenesis due to its multiple biological functions. It is a unique member of class-II HDAC enzymes. It possesses two catalytic domains, which function independently of the overall enzyme activity. Up to date, there are only a few selective HDAC6 inhibitors with anti-cancer activity. In this study, 175,204 ligands obtained from the ZINC15 and OTAVAchemical databases were used for virtual drug screening against HDAC6. Molecular docking studies were performed for 100 selected compounds. Furthermore, the top 10 compounds obtained from docking were tested for their efficacy to inhibit the function of HDAC6. Five compounds (N-(9-oxo-9H-fluoren-3-yl)benzamide, 2-hydroxy-5-[(5-oxo-6-phenyl-4,5-dihydro-1,2,4-triazin-3-yl)amino]benzoic acid, 5-(4-bromonaphthalene-1-sulfonamido)-2-hydroxybenzoic acid, 2-(naphthalen-2-yl)-N-(1H-1,2,3,4-tetrazol-5-yl)cyclopropane-1-carboxamide, and 4-oxa-5,6 diazapentacyclo[10.7.1.0³,⁷.0⁸,²⁰.0¹⁴,¹⁹]icosa-1,3(7),5,8(20),9,11,14,16,18-nonaen-13-one) inhibited enzymatic activity by more than 50 % compared to DMSO as the control. Two candidates, (N-(9-oxo-9H-fluoren-3-yl)benzamide and 5-(4-bromonaphthalene-1-sulfonamido)-2-hydroxybenzoic acid), were identified with considerable cytotoxicity towards drug-sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells. Microscale thermophoresis revealed the binding of N-(9-oxo-9H-fluoren-3-yl)benzamide and 5-(4-bromonaphthalene-1-sulfonamido)-2-hydroxybenzoic acid to purified HDAC6 protein. Both compounds induced apoptosis in a dose-dependent manner as analyzed by flow cytometry. In conclusion, we demonstrate for the first time that these two compounds bind to HDAC6, inhibit its function, and exert cytotoxic activity by apoptosis induction.

High-throughput transcriptome sequencing reveals the developmental toxicity mechanisms of niclosamide in zebrafish embryo

Niclosamide (NIC) is the most widely used molluscicides for preventing the occurrence of schistosomiasis disease, and its residues can be found in various environmental samples. However, the toxicity mechanism of NIC during early developmental stage remains largely unknown. In the present study, zebrafish embryos were acutely exposed to NIC at an environmentally realistic concentration (0 and 40 μg/L) until 120 h post-fertilization. Transcriptomic sequencing was performed to provide mechanistic insight into developmental impairment. Pathway enrichment analyses found that biological processes related to lipid metabolism were significantly affected in exposed zebrafish larvae. Consistently, biochemical measurements showed that NIC developmental exposure depleted lipid storage, elevated lipid utilization, but inhibited lipid synthesis. Furthermore, as characterized by pathway enrichment and hormonal levels, steroid hormone biosynthesis was also significantly disrupted by NIC exposure in zebrafish larvae, indicating the endocrine disrupting potential of NIC. Detoxifying phase I and II processes (e.g., metabolism, conjugation and elimination) were significantly activated by NIC exposure. Overall, our findings suggest that NIC developmental exposure at an environmentally realistic concentration disturbs the lipid metabolism, induces endocrine disruption and initiates detoxifying capacity in zebrafish larvae, which will provide preliminary clues for developmental toxicity mechanisms of NIC.

Repurposing of plant alkaloids for cancer therapy: Pharmacology and toxicology

Drug repurposing (or repositioning) is an emerging concept to use old drugs for new treatment indications. Phytochemicals isolated from medicinal plants have been largely neglected in this context, although their pharmacological activities have been well investigated in the past, and they may have considerable potentials for repositioning. A grand number of plant alkaloids inhibit syngeneic or xenograft tumor growth in vivo. Molecular modes of action in cancer cells include induction of cell cycle arrest, intrinsic and extrinsic apoptosis, autophagy, inhibition of angiogenesis and glycolysis, stress and anti-inflammatory responses, regulation of immune functions, cellular differentiation, and inhibition of invasion and metastasis. Numerous underlying signaling processes are affected by plant alkaloids. Furthermore, plant alkaloids suppress carcinogenesis, indicating chemopreventive properties. Some plant alkaloids reveal toxicities such as hepato-, nephro- or genotoxicity, which disqualifies them for repositioning purposes. Others even protect from hepatotoxicity or cardiotoxicity of xenobiotics and established anticancer drugs. The present survey of the published literature clearly demonstrates that plant alkaloids have the potential for repositioning in cancer therapy. Exploitation of the chemical diversity of natural alkaloids may enrich the candidate pool of compounds for cancer chemotherapy and -prevention. Their further preclinical and clinical development should follow the same stringent rules as for any other synthetic drug as well. Prospective randomized, placebo-controlled clinical phase I and II trials should be initiated to unravel the full potential of plant alkaloids for drug repositioning.

Repurposing an old drug for new use: Niclosamide in psoriasis-like skin inflammation

Drug discovery is an onerous, extremely expensive, and time-consuming process. Instead, drug repurposing is an attractive strategy for exploiting novel indications for a drug beyond its original use. The untapped potential of drug repurposing compensates the barriers associated with the drug discovery pipeline. Psoriasis is an autoimmune skin disease, where hyperproliferation of keratinocytes and exaggerated immune responses are the important hallmarks of the disease. Extensive in vitro and preclinical research has demonstrated that niclosamide was found to exert potent anticancer and anti-inflammatory properties by targeting STAT3, p65 NF-κB, and NFATc-1 signaling paradigm with minimal host toxicity. From the disease perspective, the static intracellular molecular network in both cancer and psoriasis share overlapping pathological features in terms of hyperproliferation and chronic inflammation, which is mediated by the aforementioned signaling cascade. The plausible mechanistic relevance has prompted us to investigate the implementation of niclosamide for repositioning in psoriasis. Our in vitro and in vivo findings suggest that niclosamide inhibits keratinocytes hyperproliferation by reactive oxygen species-mediated apoptosis through the loss of mitochondrial membrane potential, cell cycle arrest at Sub G1 phase, and DNA fragmentation. Furthermore, niclosamide treatment resulted in abrogation of lipopolysaccharide-induced inflammatory cytokine levels in murine macrophages. Additionally, our results provided a preclinical rationale in imiquimod (IMQ)-induced BALB/c mouse model, where niclosamide diligently mitigated the IMQ-induced epidermal hyperplasia and inflammation by downregulating STAT3, p65 NF-κB, and NFATc-1 transcription factors along with Akt, Ki-67, and ICAM-1 protein expression.

Design and synthesis of anticancer 1-hydroxynaphthalene-2-carboxanilides with a p53 independent mechanism of action

A series of 116 small-molecule 1-hydroxynaphthalene-2-carboxanilides was designed based on the fragment-based approach and was synthesized according to the microwave-assisted protocol. The biological activity of all of the compounds was tested on human colon carcinoma cell lines including a deleted TP53 tumor suppressor gene. The mechanism of activity was studied according to the p53 status in the cell. Several compounds revealed a good to excellent activity that was similar to or better than the standard anticancer drugs. Some of these appeared to be more active against the p53 null cells than their wild-type counterparts. Intercalating the properties of these compounds could be responsible for their mechanism of action.

Bioenergetic modulation with the mitochondria uncouplers SR4 and niclosamide prevents proliferation and growth of treatment-naïve and vemurafenib-resistant melanomas

BRAF mutations are detected in >50% of all melanomas. These mutations impair the LKB1-AMPK signaling, an important metabolic pathway associated with cell growth, proliferation and survival. Melanoma patients with BRAF mutations are usually treated with BRAF inhibitors such as vemurafenib, but responses are short-lived as drug resistant tumors metabolically switch to mitochondrial oxidative phosphorylation (OXPHOS) to escape metabolic stress-induced BRAF inhibition. Additionally, a large subset of melanoma utilizes OXPHOS in their metabolism, which can confer de novo resistance to BRAF inhibitors. Therefore, uncoupling of OXPHOS to perturb energy homeostasis and to indirectly stimulate AMPK could be a novel treatment for melanoma and to overcome intrinsic and acquired resistance to BRAF inhibitors. Here, we investigated the effects of SR4 and niclosamide, two small molecule mitochondria uncouplers, on the growth and proliferation of treatment-naïve and vemurafenib-resistant melanomas in vitro and in vivo. SR4 and niclosamide inhibited melanoma proliferation irrespective of BRAF/NRAS status. Melanomas with greater OXPHOS phenotype (higher OCR/ECAR), with LKB1 mutation, or with acquired resistance to vemurafenib displayed greater sensitivity to both uncouplers. More importantly, SR4 and niclosamide inhibited tumor growth in both treatment-naïve and vemurafenib-resistant xenograft mice models. Mechanistic studies indicate both uncouplers induced energetic stress, modulated the AMPK-mTOR pathway, and promoted apoptosis without affecting MEK-ERK MAPK signaling. These results suggest that uncouplers such as SR4 and niclosamide may be useful as first line treatment against melanoma regardless of BRAF/NRAS status, and as an adjuvant therapy for patients failing MAPK inhibitors.