Niclosamide suppresses Hepatoma cell proliferation via the Wnt pathway

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.

Metformin and Niclosamide Synergistically Suppress Wnt and YAP in APC-Mutated Colorectal Cancer

Simple Summary

Hyperactivation of the canonical Wnt and inactivation of the Hippo pathway are well-known genetic backgrounds for familial adenomatosis polyposis (FAP) and colorectal cancer (CRC), although the reciprocal regulation between those pathways is not yet clear. In this study, we found that Axin2, a bona fide downstream target of canonical Wnt, activates the Hippo pathway in APC-mutated CRC, limiting the therapeutic potential of niclosamide on advanced CRC through the inactivation of the Hippo pathway. To overcome the limitation, we combined niclosamide with AMPK activator metformin to activate Hippo and found that this combination synergistically suppressed canonical Wnt and activated Hippo in APC-mutated CRC. Using patient-derived cancer organoid and an APC-MIN mice model, we found the combinatory approach to be effective for APC-mutated CRC. Our results provide not only the reciprocal link between Wnt and Hippo in APC-mutated CRC, but they also provide an effective therapeutic approach with clinically available drugs for FAP and CRC patients.

Abstract

The Wnt and Hippo pathways are tightly coordinated and understanding their reciprocal regulation may provide a novel therapeutic strategy for cancer. Anti-helminthic niclosamide is an effective inhibitor of Wnt and is now in a phase II trial for advanced colorectal cancer (CRC) patients. We found that Axin2, an authentic target gene of canonical Wnt, acts as aYAP phosphorylation activator in APC-mutated CRC. While niclosamide effectively suppresses Wnt, it also inhibits Hippo, limiting its therapeutic potential for CRC. To overcome this limitation, we utilized metformin, a clinically available AMPK activator. This combinatory approach not only suppresses canonical Wnt activity, but also inhibits YAP activity in CRC cancer cells and in patient-derived cancer organoid through the suppression of cancer stemness. Further, combinatory oral administration suppressed in vivo tumorigenesis and the cancer progression of APC-MIN mice models. Our observations provide not only a reciprocal link between Wnt and Hippo, but also clinically available novel therapeutics that are able to target Wnt and YAP in APC-mutated CRC.

Niclosamide-loaded polymeric micelles ameliorate hepatocellular carcinoma in vivo through targeting Wnt and Notch pathways

AIM

Niclosamide (NIC) is an anthelmintic agent repurposed as a potent anticancer agent. However, its use is hindered by its poor solubility. We investigated the underlying mechanisms of NIC anticancer activity employing a novel oral NIC pluronic-based nanoformulation and tested its effect in thioacetamide-induced hepatocellular carcinoma (HCC) in rats. We evaluated its antitumor effect through regulating Wnt/β-catenin and Notch signaling pathways and apoptosis.

MAIN METHODS

Niclosamide-loaded pluronic nanoparticles (NIC-NPs) were optimally developed and characterized with sustained release properties up to 7 days. Sixteen weeks after HCC induction, NIC (70 mg/kg) and an equivalent dose of NIC-NPs were administered orally for 3 consecutive weeks. Hepatocyte integrity was assessed by measuring serum levels of aminotransferases, ALP, GGT, bilirubin, albumin and total protein. HCC development was detected by measuring AFP expression. Necroinflammation and fibrosis were scored by histopathological examination. Wnt/β-catenin and Notch signaling were evaluated by measuring hepatic mRNA levels of Wnt3A, Lrp5 and Lrp6 Co-receptors, Dvl-2, Notch1 and Hes1 and β-catenin protein levels. Apoptosis was assessed by measuring mRNA and protein levels of cyclin D1 and caspase-3.

KEY FINDING

The novel NIC-NPs restored liver integrity, reduced AFP levels and showed improved anticancer and proapoptotic activities compared to drug alone. The inhibitory effect of NIC on Wnt/β-catenin and Notch signaling pathways was potentiated by the NIC-NPs formulation.

SIGNIFICANCE

We conclude that NIC acts by inhibiting Wnt/β-catenin and Notch signaling and inducing apoptosis in HCC. Developing pluronic-based nanoformulations may be a promising approach to improve NIC solubility and offer the possibility of controlled release.

Niclosamide inhibits the cell proliferation and enhances the responsiveness of esophageal cancer cells to chemotherapeutic agents

Niclosamide is an FDA-approved anthelmintic drug, and may elicit antineoplastic effects through direct STAT3 inhibition, which has been revealed in numerous human cancer cells. Chemotherapy is the standard treatment for advanced esophageal cancers, but also causes severe systemic side effects. The present study represents the first study evaluating the anticancer efficacy of niclosamide in esophageal cancers. Through western blot assay, it was demonstrated that niclosamide suppressed the STAT3 signaling pathway in esophageal adenocarcinoma cells (BE3) and esophageal squamous cell carcinoma cells (CE48T and CE81T). In addition, niclosamide inhibited cell proliferation as determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and soft agar colony forming assay, and induced cell apoptosis as determined by Annexin V and PI staining. The induction of p21 and G1 arrest of the cell cycle also was revealed in niclosamide-treated CE81T cells by qPCR and flow cytometric assays, respectively. Furthermore, in the combination analysis of niclosamide and chemotherapeutic agents by MTS assay, low IC₅₀ values were detected in cells co-treated with niclosamide, with the exception of cisplatin-treated CE81T cells. To confirm the results using an apoptosis assay, the apoptotic enhancement of niclosamide was only demonstrated in CE48T cells co-treated with 5-FU, cisplatin, or paclitaxel, and in BE3 cells co-treated with paclitaxel, but not in CE81T cells. These findings indicate a future clinical application of niclosamide in esophageal cancers.

Stress Conditions Induced by Locoregional Therapies Stimulate Enrichment and Proliferation of Liver Cancer Stem Cells

PURPOSE

This study tested the hypothesis that stress conditions that simulated percutaneous thermal ablation (PTA), transarterial embolization (TAE), or transarterial chemoembolization stimulated enrichment of hepatocellular carcinoma (HCC) cancer stem cells (hCSCs) and that hCSC inhibitors can suppress this effect.

MATERIALS AND METHODS

Human HCC cell lines HepG2 and PLC/PRF/5 were subjected to a 46.5°C heat bath for 10 minutes or to 1% hypoxia for 72 hours without fetal bovine serum and with or without doxorubicin. Cells were then treated with a β-catenin inhibitor (FH535 or XAV939), a PI3 kinase inhibitor (Ly294002), or niclosamide, a US Food and Drug Administration-approved antihelminthic drug that acts as a mitochondrial decoupler and mixed inhibitor. Surviving cells were analyzed for hCSC markers by flow cytometry, for stemness by colony-forming assay or sphere-forming assay, and for proliferative capacity by MTT assay (where MTT is 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide). Expression of proteins related to CSC renewal and proliferation were analyzed by immunoblotting and immunostaining.

RESULTS

Conditions that simulated PTA, TAE, and transarterial chemoembolization resulted in an enrichment of cells bearing hCSC markers (CD133, CD44, and EpCAM). Cells surviving heat stress exhibited higher colony- or sphere-forming capacity and a greater proliferative state. These effects could be suppressed by niclosamide and inhibitors of β-catenin and PI3 kinase.

CONCLUSIONS

Stress conditions induced by locoregional therapies stimulated hCSC enrichment and proliferation, which could be suppressed by niclosamide and inhibitors of pathways important for hCSC renewal. Future studies will determine whether combining locoregional therapies with adjuvant hCSC inhibitors reduces HCC recurrence.

Computational Discovery of Niclosamide Ethanolamine, a Repurposed Drug Candidate That Reduces Growth of Hepatocellular Carcinoma Cells In Vitro and in Mice by Inhibiting Cell Division Cycle 37 Signaling

BACKGROUND & AIMS

Drug repositioning offers a shorter approval process than new drug development. We therefore searched large public datasets of drug-induced gene expression signatures to identify agents that might be effective against hepatocellular carcinoma (HCC).

METHODS

We searched public databases of messenger RNA expression patterns reported from HCC specimens from patients, HCC cell lines, and cells exposed to various drugs. We identified drugs that might specifically increase expression of genes that are down-regulated in HCCs and reduce expression of genes up-regulated in HCCs using a nonparametric, rank-based pattern-matching strategy based on the Kolmogorov-Smirnov statistic. We evaluated the anti-tumor activity of niclosamide and its ethanolamine salt (NEN) in HCC cell lines (HepG2, Huh7, Hep3B, Hep40, and PLC/PRF/5), primary human hepatocytes, and 2 mouse models of HCC. In one model of HCC, liver tumor development was induced by hydrodynamic delivery of a sleeping beauty transposon expressing an activated form of Ras (v12) and truncated β-catenin (N90). In another mouse model, patient-derived xenografts were established by implanting HCC cells from patients into livers of immunocompromised mice. Tumor growth was monitored by bioluminescence imaging. Tumor-bearing mice were fed a regular chow diet or a chow diet containing niclosamide or NEN. In a separate experiment using patient-derived xenografts, tumor-bearing mice were given sorafenib (the standard of care for patients with advanced HCC), NEN, or niclosamide alone; a combination of sorafenib and NEN; or a combination sorafenib and niclosamide in their drinking water, or regular water (control), and tumor growth was monitored.

RESULTS

Based on gene expression signatures, we identified 3 anthelmintics that significantly altered the expression of genes that are up- or down-regulated in HCCs. Niclosamide and NEN specifically reduced the viability of HCC cells: the agents were at least 7-fold more cytotoxic to HCCs than primary hepatocytes. Oral administration of NEN to mice significantly slowed growth of genetically induced liver tumors and patient-derived xenografts, whereas niclosamide did not, coinciding with the observed greater bioavailability of NEN compared with niclosamide. The combination of NEN and sorafenib was more effective at slowing growth of patient-derived xenografts than either agent alone. In HepG2 cells and in patient-derived xenografts, administration of niclosamide or NEN increased expression of 20 genes down-regulated in HCC and reduced expression of 29 genes up-regulated in the 274-gene HCC signature. Administration of NEN to mice with patient-derived xenografts reduced expression of proteins in the Wnt-β-catenin, signal transducer and activator of transcription 3, AKT-mechanistic target of rapamycin, epidermal growth factor receptor-Ras-Raf signaling pathways. Using immunoprecipitation assays, we found NEN to bind cell division cycle 37 protein and disrupt its interaction with heat shock protein 90.

CONCLUSIONS

In a bioinformatics search for agents that alter the HCC-specific gene expression pattern, we identified the anthelmintic niclosamide as a potential anti-tumor agent. Its ethanolamine salt, with greater bioavailability, was more effective than niclosamide at slowing the growth of genetically induced liver tumors and patient-derived xenografts in mice. Both agents disrupted interaction between cell division cycle 37 and heat shock protein 90 in HCC cells, with concomitant inhibition of their downstream signaling pathways. NEN might be effective for treatment of patients with HCC.

A Second WNT for Old Drugs: Drug Repositioning against WNT-Dependent Cancers

Aberrant WNT signaling underlies cancerous transformation and growth in many tissues, such as the colon, breast, liver, and others. Downregulation of the WNT pathway is a desired mode of development of targeted therapies against these cancers. Despite the urgent need, no WNT signaling-directed drugs currently exist, and only very few candidates have reached early phase clinical trials. Among different strategies to develop WNT-targeting anti-cancer therapies, repositioning of existing drugs previously approved for other diseases is a promising approach. Nonsteroidal anti-inflammatory drugs like aspirin, the anti-leprotic clofazimine, and the anti-trypanosomal suramin are among examples of drugs having recently revealed WNT-targeting activities. In total, 16 human-use drug compounds have been found to be working through the WNT pathway and show promise for their prospective repositioning against various cancers. Advances, hurdles, and prospects of developing these molecules as potential drugs against WNT-dependent cancers, as well as approaches for discovering new ones for repositioning, are the foci of the current review.

S100A4 in Cancer Metastasis: Wnt Signaling-Driven Interventions for Metastasis Restriction

The aberrant activity of Wnt signaling is an early step in the transformation of normal intestinal cells to malignant tissue, leading to more aggressive tumors, and eventually metastases. In colorectal cancer (CRC), metastasis accounts for about 90% of patient deaths, representing the most lethal event during the course of the disease and is directly linked to patient survival, critically limiting successful therapy. This review focuses on our studies of the metastasis-inducing gene S100A4, which we identified as transcriptional target of β-catenin. S100A4 increased migration and invasion in vitro and metastasis in mice. In patient CRC samples, high S100A4 levels predict metastasis and reduced patient survival. Our results link pathways important for tumor progression and metastasis: the Wnt signaling pathway and S100A4, which regulates motility and invasiveness. S100A4 suppression by interdicting Wnt signaling has potential for therapeutic intervention. As proof of principle, we applied S100A4 shRNA systemically and prevented metastasis in mice. Furthermore, we identified small molecule inhibitors from high-throughput screens of pharmacologically active compounds employing an S100A4 promoter-driven reporter. Best hits act, as least in part, via intervening in the Wnt pathway and restricted metastasis in mouse models. We currently translate our findings on restricting S100A4-driven metastasis into clinical practice. The repositioned FDA-approved drug niclosamide, targeting Wnt signaling, is being tested in a prospective phase II clinical trial for treatment of CRC patients. Our assay for circulating S100A4 transcripts in patient blood is used to monitor treatment success.

[Molecular mechanisms of niclosamide antitumor activity]

In this review the recent data regarding the antitumor activity of niclosamide and the molecular mechanisms of its antitumor activity are presented. Niclosamide has been used in the clinic for the treatment of intestinal parasite infections. In recent years in several screening investigations of various drugs and chemical compounds niclosamide was identified as a potential anticancer agent. Niclosamide not only inhibits the Wnt/β-catenin, mTORC1, STAT3, NF-κB and Notch signaling pathways, but also targets mitochondria in cancer cells to induce growth inhibition and apoptosis. A number of studies have established the anticancer activity of niclosamide in both in vitro and in vivo in xenotransplantation models using human tumors and immunodeficient mice. It is important that niclosamide is active not only against tumor cells but also cancer stem cells. Normal cells are resistant to niclosamide. The accumulated experimental data suggest niclosamide is a promising drug for the treatment of various types of cancer.

The anthelmintic niclosamide inhibits colorectal cancer cell lines via modulation of the canonical and noncanonical Wnt signaling pathway

BACKGROUND

Wnt/β-catenin signaling is known to play an important role in colorectal cancer (CRC). Niclosamide, a salicylamide derivative used in the treatment of tapeworm infections, targets the Wnt/β-catenin pathway. The objective of this study was to investigate niclosamide as a therapeutic agent against CRC.

METHODS

The antiproliferative effects of 1, 3, 10, and 50 μM concentrations of niclosamide on human (SW480 and SW620) and rodent (CC531) CRC cell lines were determined by MTS assay and direct cell count. The lymphoid enhancer-binding factor 1/transcription factor (LEF/TCF) reporter assay monitored the activity of Wnt signaling. Immunofluorescence staining demonstrated the expression pattern of active β-catenin. Gene expression of canonical and noncanonical Wnt signaling components was analyzed using qRT-PCR. Western blot analysis was performed with antibodies detecting nuclear localization of β-catenin and c-jun.

RESULTS

Cell proliferation in CRC cell lines was blocked dose dependently after 12 and 24 h of incubation. The Wnt promoter activity of LEF/TCF significantly decreased with niclosamide concentrations of 10 and 50 μM after 12 h of incubation. Active β-catenin did not shift from the nuclear to the cytosolic pool. However, canonical target genes (met, MMP7, and cyclin D1) as well as the coactivating factor Bcl9 were downregulated, whereas the noncanonical key player c-jun was clearly activated.

CONCLUSIONS

Niclosamide treatment is associated with an inhibitory effect on CRC development and reduced Wnt activity. It may exert its effect by interfering with the nuclear β-catenin-Bcl9-LEF/TCF triple-complex and by upregulation of c-jun representing noncanonical Wnt/JNK signaling. Thus, our findings warrant further research into this substance as a treatment option for patients with advanced CRC.

Niclosamide induced cell apoptosis via upregulation of ATF3 and activation of PERK in Hepatocellular carcinoma cells

Background

Hepatocellular carcinoma (HCC) is one of most common and aggressive human malignancies in the world, especially, in eastern Asia, and its mortality is very high at any phase. We want to investigate mechanism of niclosamide inducing cell apoptosis in HCC.

Methods

Two hepatoma cell lines were used to evaluate activity of niclosamide inducing cell apoptosis and study its mechanism. Quantitative real-time PCR and western blotting were used in analysis of genes expression or protein active regulated by niclosamide.

Results

Niclosamide remarkably induced cell apoptosis in hepatoma cells. Furthermore, our study revealed that RNA-dependent protein kinase-like kinase (PERK) is activated and its expression is up-regulated in HCC cells which are exposed to niclosamide. niclosamide also significantly increase activating transcription factor 3 (ATF3), activating transcription factor 4 (ATF4) and CCAAT/enhancer-binding protein-homologous protein (CHOP) expression in HCC cells. It’s suggested that the function of niclosamide was abrogated by PERK inhibitor or absent ATF3. Expression of PERK and CHOP is correlated with ATF3 level in the cells.

Conclusion

Taken together, our results indicate that ATF3 plays an integral role in ER stress activated and cell apoptosis induced by niclosamide in HCC cells. In this study, the new mechanism of niclosamide as anti-cancer we investigated, too.

FH535 suppresses the proliferation and motility of hepatocellular carcinoma cells

The Wnt signaling pathway is activated in hepatocellular carcinoma (HCC). This study investigated the effects of FH535, an inhibitor of the Wnt signaling pathway, on the proliferation and motility of HCC cells. HLF cells and PLC/PRF/5 cells, HCC cells, were subjected to 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay with the addition of FH535. RNA was isolated from the cells and subjected to real-time quantitative PCR. Hematoxylin and eosin (H&E) staining was performed to analyze apoptosis. A scratch assay was performed to analyze cell motility. Cell proliferation significantly decreased (P<0.05). The expression levels of cyclin D1 significantly decreased in both cell lines (P<0.05). Pyknotic nuclei were observed in the cells cultured with FH535 (50 µM). In the scratch assay, the distance between the growing edges of cells and the scratched line significantly decreased with the addition of FH535 at 50 µM (P<0.05). The expression levels of matrix metalloproteinase 9 significantly decreased at 50 µM (P<0.05). FH535 suppressed the proliferation of HCC cells by downregulating the expression of cyclin D1 and by inducing apoptosis. Further, it suppressed cell motility by downregulating the expression of matrix metalloproteinase.

Niclosamide suppresses migration of hepatocellular carcinoma cells and downregulates matrix metalloproteinase-9 expression

Metastasis negatively affects the prognosis of hepatocellular carcinoma (HCC). In the present study, niclosamide, which is known to suppress the proliferation of HCC cells, was investigated for possible suppressant effects on the migration of HCC cells. HLF and PLC/PRF/5 HCC cells were cultured in the presence of niclosamide. Cell proliferation was analyzed using the MTS assay. Cell migration was measured by performing a scratch assay. Expression levels of cyclin D1 and matrix metalloproteinase 9 (MMP9) were analyzed by performing revers transcription-quantitative polymerase chain reaction. Compared with the control treatment, treatment with 10 µm niclosamide suppressed the proliferation of the HLF and PRL/PRF/5 cells to 49.9±3.7 and 17.9±11.5% (P<0.05), respectively. Furthermore, compared with the control treatment, treatment with 1.0 µM niclosamide downregulated the expression of cyclin D1 to 52.4±4.4 and 23.9±5.4% (P<0.05) in the HLF and PRL/PRF/5 cells, respectively. In the scratch assay, treatment of the HLF cells with niclosamide (1.0 µm) decreased the distance of the scratched line from the growing edge to 4.6±1.0 mm compared with the 9.2±1.4 mm observed with the control treatment (P<0.05). Similarly, treatment of the PRL/PRF/5 cells with niclosamide (1.0 µm) also decreased the distance of the scratched line from the growing edge to 3.0±0.8 mm compared with the 5.5±0.9 mm observed with the control treatment (P<0.05). Further, MMP9 expression levels in the HLF cells treated with 1.0 µm niclosamide decreased to 22.4±1.76% (P<0.05) compared with those in the untreated control HLF cells. Similarly, expression level of MMP9 in the PRL/PRF/5 cells treated with 1.0 µm niclosamide deceased to 18.7±10.7% (P<0.05) compared with those in the untreated control PRL/PRF/5 cells. Overall, niclosamide downregulated the expression of MMP9 in and suppressed the migration of HCC cells.

Involvement of the Wnt signaling pathway in feeder‑free culture of human induced pluripotent stem cells

Activin A maintains the pluripotency of human induced pluripotent stem (hiPS) cells. A combination of activin A and CHIR99021 (CHIR), a specific inhibitor of glycogen synthase‑3β, is suitable for feeder‑free culture of hiPS cells. In the present study, the specific role of the Wnt signaling pathway in cells cultured under different conditions was investigated. Following transfection with the reporter plasmids, TOPflash and FOPflash, hiPS cells were cultured in medium, containing activin A, CHIR, leukemia inhibitory factor (LIF) or SB431542, a specific inhibitor of activin A. A luciferase reporter assay was performed 48 h later. Western blot analysis was performed to determine the expression levels of β‑catenin and tubulin‑α. The activity of Wnt in hiPS cells was suppressed by culture in the presence of activin A. The activation of the Wnt pathway was most marked when the cells were cultured with a combination of activin A and CHIR. Addition of SB431542 into the culture revealed no significant change in the Wnt pathway. Western blot analysis revealed that β‑catenin accumulated most often in cells cultured with activin A and CHIR. β‑catenin also accumulated in cells cultured with activin A alone. Culture with activin A and CHIR most effectively stimulated the Wnt signaling pathway, as measured by luciferase assays using TOPflash and FOP flash as reporter plasmids. β‑catenin accumulated in the hiPS cells cultured with activin A, via a mechanism, which remains to be elucidated. The Wnt signaling pathway may be important for hiPS cell growth in feeder‑free culture.

Repurposing salicylanilide anthelmintic drugs to combat drug resistant Staphylococcus aureus

Staphylococcus aureus is a Gram-positive bacterium that has become the leading cause of hospital acquired infections in the US. Repurposing Food and Drug Administration (FDA) approved drugs for antimicrobial therapy involves lower risks and costs compared to de novo development of novel antimicrobial agents. In this study, we examined the antimicrobial properties of two commercially available anthelmintic drugs. The FDA approved drug niclosamide and the veterinary drug oxyclozanide displayed strong in vivo and in vitro activity against methicillin resistant S. aureus (minimum inhibitory concentration (MIC): 0.125 and 0.5 μg/ml respectively; minimum effective concentration: ≤ 0.78 μg/ml for both drugs). The two drugs were also effective against another Gram-positive bacteria Enterococcus faecium (MIC 0.25 and 2 μg/ml respectively), but not against the Gram-negative species Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter aerogenes. The in vitro antimicrobial activity of niclosamide and oxyclozanide were determined against methicillin, vancomycin, linezolid or daptomycin resistant S. aureus clinical isolates, with MICs at 0.0625-0.5 and 0.125-2 μg/ml for niclosamide and oxyclozanide respectively. A time-kill study demonstrated that niclosamide is bacteriostatic, whereas oxyclozanide is bactericidal. Interestingly, oxyclozanide permeabilized the bacterial membrane but neither of the anthelmintic drugs exhibited demonstrable toxicity to sheep erythrocytes. Oxyclozanide was non-toxic to HepG2 human liver carcinoma cells within the range of its in vitro MICs but niclosamide displayed toxicity even at low concentrations. These data show that the salicylanilide anthelmintic drugs niclosamide and oxyclozanide are suitable candidates for mechanism of action studies and further clinical evaluation for treatment of staphylococcal infections.

Niclosamide inhibits the proliferation of human osteosarcoma cell lines by inducing apoptosis and cell cycle arrest

Niclosamide, used as an antihelminthic, has demonstrated some properties of anticancer effects. However, its role in osteosarcoma remains to be determined. The aim of this study was to determine the effect of niclosamide on human osteosarcoma cell lines. The human MG-63 and U2OS osteosarcoma cell lines were treated with different concentrations of niclosamide. The cell inhibitory rate was calculated by CCK-8 assay. Cell cycle was detected by flow cytometry. Cell apoptosis was determined by Hoechst 33324 staining, flow cytometry and fluorescence microscope, respectively. The expression of bcl-2, bax and pro-caspase-3 were measured by western blotting. Niclosamide exerted an inhibitory effect on the two cell lines in a time- and dose-dependent manner. Niclosamide was found to induce the arrest of S and G2/M phase in U2OS cells and G2/M in MG-63 cells. Moreover, niclosamide induced apoptosis in MG-63 and U2OS cells. The bax/bcl-2 ratio increased while the expression of pro‑caspase-3 decreased significantly in the two cell lines. The results indicated that niclosamide inhibits proliferation, and induces apoptosis and cell cycle arrest in human osteosarcoma cell lines.

Gastric cancer cell proliferation is suppressed by frizzled-2 short hairpin RNA

In order to identify novel targets for the molecular therapy of gastric cancer (GC), we investigated the mRNA and protein expression of frizzled-2 (Fz2), a Wnt signaling pathway receptor. Reverse-transcriptase polymerase chain reaction (PCR) amplification was utilized to determine the expression patterns of Fz genes in normal stomach and in the GC cell lines MKN45 and MKN74. Immunostaining was performed on surgical specimens of GC using an antibody against Fz2. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2- (4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay was performed on MKN45 cells and MKN74 cells transfected with Fz2 short-hairpin (sh) RNA. Cell motility was analyzed by scratch assay following Fz2 shRNA. Real-time quantitative PCR was performed to analyze the expression levels of cyclin D1 and matrix metallopeptidase 9 (MMP-9). Fz1, 3, 6 and 8 were expressed in normal stomach, and in MKN45 and MKN74 cells. Fz2 was expressed in normal stomach and in MKN45, but not in MKN74 cells. Well-differentiated GC tissue was weakly positive for Fz2 in cell membranes. Fz2 was positive in both the cell membrane and cytoplasm of GC tissues of moderately differentiated and poorly differentiated adenocarcinoma. Signet ring cells were positive for cytoplasmic Fz2. Proliferation of MKN45 and MKN74 cells was suppressed by Fz2 shRNA, and a scratch assay demonstrated that Fz2 shRNA suppressed also MKN45 and MKN74 cell motility. Furthermore, Fz2 shRNA application led to downregulated mRNA expression of both cyclin D1 and MMP-9. Fz2, 3, 6 and 8 were expressed in normal stomach, and in MKN45 and MKN74 GC cells. Fz2 shRNA suppressed cell proliferation and motility of MKN45 and MKN74 cells, and downregulated cyclin D1 and MMP-9 expression in these GC cell lines.

Co-culture of hepatocellular carcinoma cells and human umbilical endothelial cells damaged by SU11274

Mesenchymal-epithelial transition factor (c-Met) is a receptor that binds to the hepatocyte growth factor and is upregulated in hepatocellular carcinoma (HCC). The anti-tumor effects of (3Z)-N-(3-chlorophenyl)-3-({3,5-dimethyl-4-[(4- methyl-piperazin-1-yl)carbonyl]-1H-pyrrol-2-yl}methylene)-N-me- thyl-2-oxo-2,3-dihydro-1H-indole-5-sulfonamide (SU11274), a c-Met inhibitor, were investigated in the present study. HCC cells (HLE, HLF, PLC/PRL/5, Hep3B, Huh-6 and HepG2) and human umbilical vein endothelial cells (HUVECs) were used. Quantitative polymerase chain reaction was performed to detect the expression level of c-Met in HCC and HUVECs, and cyclin D1 in HCC. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-car-boxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt assay was performed to assess the proliferation of the HCC cells and HUVECs cultured with SU11274. Co-culture of HLF or PLC/PRL/5 cells and HUVECs was established as an in vitro model of HCC tissues. The expression levels of c-Met in HLE, HLF, PLC/PRL/5, Hep3B, Huh-6 and HepG2, adult healthy liver and HUVECs were 4.43±0.50, 1.61±0.18, 3.70±0.08, 0.81±0.18, 6.60±1.29, 1.06±0.35, 1.00±0.09 and 88.8±17.3 (mean ± standard deviation), respectively. SU11274 (30 μM) suppressed the proliferation of HLF, PLC/PRL/5 and HUVECs to 11.0±9.4, 46.5±30.7 and 29.4±5.0%, respectively. SU11274 (30 μM) decreased the expression levels of cyclin D1 in HLF and PLC/PRL/5 cells to 45.1±11.6 and 30.1±10.3%, respectively. SU11274, at a concentration of 30 μM damaged the morphology of the co-cultures of HLF or PLC/PRL/5 cells with HUVECs and all the cells died. c-Met is highly expressed in HUVECs and HCC cells, but not in Hep3B. At a 30-μM concentration, SU11274 suppresses the proliferation of HLF, PLC/PRL/5 and HUVECs. SU11274 (30 μM) damages the co-cultures of HLF or PLC/PRL/5 cells with HUVECs.

Targeting the Wnt pathway in human cancers: therapeutic targeting with a focus on OMP-54F28

The Wnt signaling pathways are a group of signal transduction pathways that play an important role in cell fate specification, cell proliferation and cell migration. Aberrant signaling in these pathways has been implicated in the development and progression of multiple cancers by allowing increased proliferation, angiogenesis, survival and metastasis. Activation of the Wnt pathway also contributes to the tumorigenicity of cancer stem cells (CSCs). Therefore, inhibiting this pathway has been a recent focus of cancer research with multiple targetable candidates in development. OMP-54F28 is a fusion protein that combines the cysteine-rich domain of frizzled family receptor 8 (Fzd8) with the immunoglobulin Fc domain that competes with the native Fzd8 receptor for its ligands and antagonizes Wnt signaling. Preclinical models with OMP-54F28 have shown reduced tumor growth and decreased CSC frequency as a single agent and in combination with other chemotherapeutic agents. Due to these findings, a phase 1a study is nearing completion with OMP-54F28 in advanced solid tumors and 3 phase 1b studies have been opened with OMP-54F28 in combination with standard-of-care chemotherapy backbones in ovarian, pancreatic and hepatocellular cancers. This article will review the Wnt signaling pathway, preclinical data on OMP-54F28 and other Wnt pathway inhibitors and ongoing clinical trials.