Influence of levamisole and other angiogenesis inhibitors on angiogenesis and endothelial cell morphology in vitro

The potential immunomodulatory effect of levamisole in humans and farm animals

This study conducted a literature review to investigate the immunomodulatory effect of levamisole in both humans and farm animals. The following procedure was followed for database searching: PubMed, Google Scholar, Web of Science, and Cochrane Library. All research works were updated to September 2022. The terms used in the literature search were included: ("levamisole" OR "immunity" OR "immune system") AND ("adjuvant" OR "fish" OR "poultry" OR "farm animal" OR "cattle" OR "sheep"). The current review enlightens the extensive potential of levamisole as an adjuvant immunotherapeutic agent and explains its divergent applications beyond its antiparasitic use as an adjuvant, dietary supplement, immunostimulant, antiviral, and anti-cancer drug in humans and farm animals. In the articles examined, various mechanisms have been proposed for levamisole immunoprotective effects, but hormonal alteration and stress hormone reduction are indicated as the main mechanisms in various animal species.

Functional importance of coacervation to convert calcium polyphosphate nanoparticles into the physiologically active state

Inorganic polyphosphates (polyP) are of increasing medical interest due to their unprecedented ability to exhibit both morphogenetic and ATP-delivering properties. However, these polymers are only physiologically active in the coacervate state, but not as amorphous nanoparticles (NP), the storage form of the polymer. Little is known about the mechanism of formation and interconversion of these two distinct polyP phases in the presence of metal ions. Based on in silico simulation studies, showing a differential clustering of polyP and calcium ions, the pH-dependent NP and coacervate formation of polyP was examined experimentally. Turbidimetric studies showed that Ca-polyP coacervate formation at pH 7 is a slow process compared to NP formation at pH 10. In FTIR spectra, the asymmetric stretching vibration signal of the internal (PO₂)⁻ units, which is present in the Ca-polyP coacervate formed at pH 7, disappears in the NP formed at pH 10 using the conventional method (dropping of a CaCl₂ solution into a Na-polyP solution). Surprisingly, when reversing the procedure, adding Na-polyP to CaCl₂, a coacervate is obtained at both pH 7 and pH 10, as confirmed by SEM and FTIR analyses. The (PO₂)⁻ signal also disappears when Ca-polyP-NP are exposed to peptides, leading to the transformation of the NP into the coacervate phase. From these results, a mechanistic model of pH-dependent coacervate and NP formation is proposed that considers not only electrostatic ion-ion but also ion-dipole interactions. Functional studies revealed a delayed polyP release kinetics for Ca-polyP-NP embedded in a hydrogel due to NP/coacervate conversion. Human A549 epithelial cells grown on the coacervate show increased proliferation and ATP production compared to cells cultured on particulate polyP. Ca-polyP NP taken up by endocytosis undergo intracellular coacervate transformation. Understanding the differential expression of the two polyP phases is of functional importance for the potential therapeutic application of this physiological, regeneratively active polymer.

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Polyphosphate (polyP) is a polymer that is abundantly formed in blood platelets.

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This polyanionic polymer exists both in the form of soluble polyP chains and as nanoparticles.

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PolyP polymers must undergo coacervation before reaching functional activity.

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Coacervation is based on a redistribution of the Ca²⁺ and polyP ions, distinct from nanoparticle formation.

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In the coacervate state, polyP causes cell proliferation and ATP generation.

Combining locoregional CAR-T cells, autologous + allogeneic tumor lysate vaccination and levamisole in treatment of glioblastoma

Glioblastoma multiforme (GBM) is an aggressive brain malignancy and harbors a microenvironment limiting immune cells activity. CAR-T cells are being tested in the treatment of cancers and there exist reports which demonstrate dramatic regression of multicentric GBMs following intrathecal treatment with CAR-T cells. In this article, a triple approach for immune treatment of GBM is proposed. First, GBM tumor specimens for each patient will be saved and cultured to obtain tumor lysates. Then, levamisole will be applied, which possesses immunostimulating, anti-glycolytic, and anti-angiogenic features. Following priming the immune system, GBM patients will be injected with lysates of their own tumor cells plus lysates from a GBM cell line, U251. After 3 months of this treatment, CAR-T cells (transduced with IL13Rα2-CAR) will be applied via intratumoral approach. As such, genetically-modified and native immunocytes may 'meet' in the vicinity of deeply-invading tumor cells and demonstrate greater efficacy via cell-cell interactions. By this, a self-propagating cyclic process - a cancer-immunity cycle - may be initiated to eradicate cancer cells.

In Vitro Angiogenesis Inhibition and Endothelial Cell Growth and Morphology

A co-culture assay with human umbilical vein endothelial cells (HUVECs) and normal human dermal fibroblasts (NHDFs) was used to study whether selected angiogenesis inhibitors were able to inhibit differentiation and network formation of HUVECs in vitro. The effect of the inhibitors was determined by the morphology and the calculated percentage area covered by HUVECs. Neutralizing VEGF with avastin and polyclonal goat anti-VEGF antibody and inhibiting VEGFR2 with sorafenib and vatalanib resulted in the formation of HUVEC clusters of variable sizes as a result of inhibited EC differentiation. Furthermore, numerous inhibitors of the VEGF signaling pathways were tested for their effect on the growth and differentiation of HUVECs. The effects of these inhibitors did not reveal a cluster morphology, either individually or when combined to block VEGFR2 downstream pathways. Only the addition of N-methyl-p-bromolevamisole revealed a similar morphology as when targeting VEGF and VEGFR2, meaning it may have an inhibitory influence directly on VEGFR signaling. Additionally, several nuclear receptor ligands and miscellaneous compounds that might affect EC growth and differentiation were tested, but only dexamethasone gave rise to cluster formation similarly to VEGF-neutralizing compounds. These results point to a link between angiogenesis, HUVEC differentiation and glucocorticoid receptor activation.

An unexpected biomaterial against SARS-CoV-2: Bio-polyphosphate blocks binding of the viral spike to the cell receptor

No other virus after the outbreak of the influenza pandemic of 1918 affected the world's population as hard as the coronavirus SARS-CoV-2. The identification of effective agents/materials to prevent or treat COVID-19 caused by SARS-CoV-2 is an urgent global need. This review aims to survey novel strategies based on inorganic polyphosphate (polyP), a biologically formed but also synthetically available polyanionic polymeric material, which has the potential of being a potent inhibitor of the SARS-CoV-2 virus-cell-docking machinery. This virus attaches to the host cell surface receptor ACE2 with its receptor binding domain (RBD), which is present at the tips of the viral envelope spike proteins. On the surface of the RBD an unusually conserved cationic groove is exposed, which is composed of basic amino acids (Arg, Lys, and His). This pattern of cationic amino acids, the cationic groove, matches spatially with the anionic polymeric material, with polyP, allowing an electrostatic interaction. In consequence, the interaction between the RBD and ACE2 is potently blocked. PolyP is a physiological inorganic polymer, synthesized by cells and especially enriched in the blood platelets, which releases metabolically useful energy through enzymatic degradation and coupled ADP/ATP formation. In addition, this material upregulates the steady-state-expression of the mucin genes in the epithelial cells. We propose that polyP, with its two antiviral properties (blocking the binding of the virus to the cells and reinforcing the defense barrier against infiltration of the virus) has the potential to be a novel protective/therapeutic anti-COVID-19 agent.

Mechanisms of action of metformin and its regulatory effect on microRNAs related to angiogenesis

Angiogenesis is rapidly initiated in response to pathological conditions and is a key target for pharmaceutical intervention in various malignancies. Anti-angiogenic therapy has emerged as a potential and effective therapeutic strategy for treating cancer and cardiovascular-related diseases. Metformin, a first-line oral antidiabetic agent for type 2 diabetes mellitus (T2DM), not only reduces blood glucose levels and improves insulin sensitivity and exerts cardioprotective effects but also shows benefits against cancers, cardiovascular diseases, and other diverse diseases and regulates angiogenesis. MicroRNAs (miRNAs) are endogenous noncoding RNA molecules with a length of approximately 19-25 bases that are widely involved in controlling various human biological processes. A large number of miRNAs are involved in the regulation of cardiovascular cell function and angiogenesis, of which miR-21 not only regulates vascular cell proliferation, migration and apoptosis but also plays an important role in angiogenesis. The relationship between metformin and abnormal miRNA expression has gradually been revealed in the context of numerous diseases and has received increasing attention. This paper reviews the drug-target interactions and drug repositioning events of metformin that influences vascular cells and has benefits on angiogenesis-mediated effects. Furthermore, we use miR-21 as an example to explain the specific molecular mechanism underlying metformin-mediated regulation of the miRNA signaling pathway controlling angiogenesis and vascular protective effects. These findings may provide a new therapeutic target and theoretical basis for the clinical prevention and treatment of cardiovascular diseases.

Morphogenetic (Mucin Expression) as Well as Potential Anti-Corona Viral Activity of the Marine Secondary Metabolite Polyphosphate on A549 Cells

The mucus layer of the nasopharynx and bronchial epithelium has a barrier function against inhaled pathogens such as the coronavirus SARS-CoV-2. We recently found that inorganic polyphosphate (polyP), a physiological, metabolic energy (ATP)-providing polymer released from blood platelets, blocks the binding of the receptor binding domain (RBD) to the cellular ACE2 receptor in vitro. PolyP is a marine natural product and is abundantly present in marine bacteria. Now, we have approached the in vivo situation by studying the effect of polyP on the human alveolar basal epithelial A549 cells in a mucus-like mucin environment. These cells express mucins as well as the ectoenzymes alkaline phosphatase (ALP) and adenylate kinase (ADK), which are involved in the extracellular production of ATP from polyP. Mucin, integrated into a collagen-based hydrogel, stimulated cell growth and attachment. The addition of polyP to the hydrogel significantly increased cell attachment and also the expression of the membrane-tethered mucin MUC1 and the secreted mucin MUC5AC. The increased synthesis of MUC1 was also confirmed by immunostaining. This morphogenetic effect of polyP was associated with a rise in extracellular ATP level. We conclude that the nontoxic and non-immunogenic polymer polyP could possibly also exert a protective effect against SARS-CoV-2-cell attachment; first, by stimulating the innate antiviral response by strengthening the mucin barrier with its antimicrobial proteins, and second, by inhibiting virus attachment to the cells, as deduced from the reduction in the strength of binding between the viral RBD and the cellular ACE2 receptor.

Levamisole enhances DR4-independent apoptosis induced by TRAIL through inhibiting the activation of JNK in lung cancer

THE HEADINGS AIMS

Levamisole has anti-parasite and antitumor activities, but the anti-lung cancer mechanism has not been studied. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is regarded as a promising drug because of the ability to selectively target cancer cells. However, the tolerance of cancer cells to TRAIL limits its antitumor activity. Other drugs combined with TRAIL need to be explored to enhance its antitumor activity. Based on the adjuvant anticancer effect of levamisole on anticancer drugs activity, the antitumor activity of levamisole combined with TRAIL will be investigated.

MATERIALS AND METHODS

In vitro and in vivo experiments were employed to investigate the anti-tumor activity. Flow-cytometry analysis, western blotting and siRNA transfection were used to explore the molecular mechanism.

KEY FINDINGS

Levamisole decreased the proliferation of lung cancer cells in vitro and in vivo and induced cell cycle arrest in G0/G1 phase. Besides, levamisole also enhanced TRAIL-induced DR4-independent apoptosis by inhibiting the phosphorylation of cJUN. A new cellular protective pathway LC3B-DR4/Erk was also disclosed, in which levamisole only increased the expression of LC3B and then activated the phosphorylation of Erk and increased the expression of DR4, while p-Erk and DR4 inter-regulated.

SIGNIFICANCE

Levamisole may be used as an adjuvant of TRAIL in treating lung cancer. The discovery of LC3B-DR4/Erk as a new protective pathway provides a new direction for sensitizing lung cancer cells to TRAIL.

Inorganic Polyphosphates As Storage for and Generator of Metabolic Energy in the Extracellular Matrix

Inorganic polyphosphates (polyP) consist of linear chains of orthophosphate residues, linked by high-energy phosphoanhydride bonds. They are evolutionarily old biopolymers that are present from bacteria to man. No other molecule concentrates as much (bio)chemically usable energy as polyP. However, the function and metabolism of this long-neglected polymer are scarcely known, especially in higher eukaryotes. In recent years, interest in polyP experienced a renaissance, beginning with the discovery of polyP as phosphate source in bone mineralization. Later, two discoveries placed polyP into the focus of regenerative medicine applications. First, polyP shows morphogenetic activity, i.e., induces cell differentiation via gene induction, and, second, acts as an energy storage and donor in the extracellular space. Studies on acidocalcisomes and mitochondria provided first insights into the enzymatic basis of eukaryotic polyP formation. In addition, a concerted action of alkaline phosphatase and adenylate kinase proved crucial for ADP/ATP generation from polyP. PolyP added extracellularly to mammalian cells resulted in a 3-fold increase of ATP. The importance and mechanism of this phosphotransfer reaction for energy-consuming processes in the extracellular matrix are discussed. This review aims to give a critical overview about the formation and function of this unique polymer that is capable of storing (bio)chemically useful energy.

Role of ATP during the initiation of microvascularization: acceleration of an autocrine sensing mechanism facilitating chemotaxis by inorganic polyphosphate

The in vitro tube formation assay with human umbilical vein endothelial cells (HUVEC) was applied to identify the extra- and intracellular sources of metabolic energy/ATP required for cell migration during the initial stage of microvascularization. Extracellularly, the physiological energy-rich polymer, inorganic polyphosphate (polyP), applied as biomimetic amorphous calcium polyP microparticles (Ca-polyP-MP), is functioning as a substrate for ATP generation most likely via the combined action of the alkaline phosphatase (ALP) and the adenylate kinase (AK). The linear Ca-polyP-MP with a size of 40 phosphate units, close to the polyP in the acidocalcisomes in the blood platelets, were found to increase endothelial cell tube formation, as well as the intracellular ATP levels. Depletion of extracellular ATP with apyrase suppressed tube formation during the initial incubation period. Inhibition experiments revealed that inhibitors (levamisole and Ap5A) of the enzymes involved in extracellular ATP generation strongly reduce the Ca-polyP-MP-induced tube formation. The stimulatory effect of Ca-polyP-MP was also diminished by the glycolysis inhibitor oxamate and trifluoperazine which blocks endocytosis, as well as by MRS2211, an antagonist of the P2Y₁₃ receptor. Oligomycin, an inhibitor of the mitochondrial F₀F₁-ATP synthase, displayed no effect at lower concentrations on tube formation. Electron microscopic data revealed that after cellular uptake, the Ca-polyP-MP accumulate close to the cell membrane. We conclude that in HUVEC exposed to polyP, ATP is formed extracellularly via the coupled ALP-AK reaction, and intracellularly during glycolysis. The results suggest an autocrine signaling pathway of ATP with polyP as an extracellular store of metabolic energy for endothelial cell migration during the initial vascularization process.

The anti-angiogenic potential of (±) gossypol in comparison to suramin

Cotton, a staple fiber that grows around the seeds of the cotton plants (Gossypium), is produced throughout the world, and its by products, such as cotton fibers, cotton-seed oil, and cottonseed proteins, have a variety of applications. Cotton-seed contains gossypol, a natural phenol compound. (±)-Gossypol is a yellowish polyphenol that is derived from different parts of the cotton plant and contains potent anticancer properties. Tumor growth and metastasis are mainly related to angiogenesis; therefore, anti-angiogenic therapy targets the new blood vessels that provide oxygen and nutrients to actively proliferating tumor cells. The aim of the present study was to evaluate the anti-angiogenic potential of (±)-gossypol in vitro. (±)-Gossypol has anti-proliferative effects on cancer cell lines; however, its anti-angiogenic effects on normal cells have not been studied. Anti-proliferative activities of gossypol assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, anti-angiogenic activities using tube formation assay, and cell migration inhibition capability using a wound-healing assay on human umbilical vein endothelial cells (HUVECs) were revealed. (±)-Gossypol displayed the following potent anti-angiogenic activities in vitro: it inhibited the cell viability of HUVECs, it inhibited the migration of HUVECs, and disrupted endothelial tube formation in a dose-dependent manner. In addition, the anti-angiogenic effects of (±)-gossypol were investigated in ovo in a model using a chick chorioallantoic membrane (CAM). Decreases in capillary density were assessed and scored. (±)-Gossypol showed dose-dependent anti-angiogenic effects on CAM. These findings suggest that (±)-gossypol can be used as a new anti-angiogenic agent.

Salubrinal attenuated retinal neovascularization by inhibiting CHOP-HIF1α-VEGF pathways

Retinal neovascularization (RNV) related disease is the leading cause of irreversible blindness in the world. The aim of this study is to identify whether salubrinal could attenuate RNV by inhibiting CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP)- hypoxia inducible factors 1α (HIF1α) -vascular endothelial growth factor (VEGF) pathways in both mouse retinal microvascular endothelial cells (mRMECs) and oxygen-induced retinopathy (OIR) mouse model. After being treated with salubrinal (20μmol/L) or CHOP-siRNA, mRMECs were exposed to a hypoxia environment. OIR mice were intraperitoneally injected with salubrinal (0.5 mg/kg/day) from P12 to P17. With salubrinal or CHOP-siRNA treatment, the elevated CHOP protein and mRNA levels in hypoxia-induced mRMECs were significantly decreased. HIF1α-VEGF pathways were activated under hypoxia condition, then HIF1α protein was degraded and VEGF secretion was down-regulated after salubrinal or CHOP-siRNA treatment. In OIR mice, the areas of RNV were markedly decreased with salubrinal treatment. Moreover, elevated expressions of CHOP, HIF1α and VEGF in retinas of OIR mice were all reduced after salubrinal treatment. It suggested that salubrinal attenuated RNV in mRMECs and OIR mice by inhibiting CHOP-HIF1α-VEGF pathways and could be a potential therapeutic target for hypoxia-induced retinal microangiopathy.

Versatile synthetic alternatives to Matrigel for vascular toxicity screening and stem cell expansion

The physiological relevance of Matrigel as a cell-culture substrate and in angiogenesis assays is often called into question. Here, we describe an array-based method for the identification of synthetic hydrogels that promote the formation of robust in vitro vascular networks for the detection of putative vascular disruptors, and that support human embryonic stem cell expansion and pluripotency. We identified hydrogel substrates that promoted endothelial-network formation by primary human umbilical vein endothelial cells and by endothelial cells derived from human induced pluripotent stem cells, and used the hydrogels with endothelial networks to identify angiogenesis inhibitors. The synthetic hydrogels show superior sensitivity and reproducibility over Matrigel when evaluating known inhibitors, as well as in a blinded screen of a subset of 38 chemicals, selected according to predicted vascular disruption potential, from the Toxicity ForeCaster library of the US Environmental Protection Agency. The identified synthetic hydrogels should be suitable alternatives to Matrigel for common cell-culture applications.

Xiaotan Sanjie decoction inhibits angiogenesis in gastric cancer through Interleukin-8-linked regulation of the vascular endothelial growth factor pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Interleukin-8 (IL-8) as a pro-angiogenic factor is strongly associated with gastric cancer metastasis. Xiaotan Sanjie (XTSJ) decoction is an empirical compound prescription based on the phlegm theory of traditional Chinese medicine. Previous studies have shown that XTSJ decoction decreases IL-8 level and formation of vasculogenic mimicry of gastric cancer.

AIM OF THE STUDY

To investigate the link between Xiaotan Sanjie (XTSJ) decoction and IL-8 regulation in the angiogenesis of gastric cancer.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were co-cultured with SGC-7901 human gastric cancer cells and exposed to serum samples containing XTSJ decoction and/or IL-8 (1.0ng/mL). The canalization and migration capacities were evaluated by tube formation and transwell migration assay. Protein (immunofluorescence and Western blot) and mRNA (qPCR) expressions were measured in 24-h-cultured HUVECs for vascular endothelial growth factor-A (VEGF-A), vascular endothelial growth factor receptor (VEGFR)-1, and VEGFR-2.

RESULTS

IL-8 significantly promoted and XTSJ decoction inhibited HUVEC tube formation and migration. Links between IL-8 regulation and XTSJ decoction were found in tube formation and migration assays. IL-8 upregulated and XTSJ decoction downregulated VEGF-A, VEGFR-1, and VEGFR-2 protein levels. XTSJ decoction inhibited IL-8-induced VEGF-A and VEGFR-1 protein expressions. Similarly, IL-8 promoted VEGF-A, VEGFR-1, and VEGFR-2 mRNA levels; however, XTSJ decoction inhibited only VEGF-A mRNA. Interestingly, XTSJ decoction inhibited IL-8-induced VEGFR-1 and VEGFR-2 mRNA expression.

CONCLUSION

XTSJ decoction might inhibit angiogenesis in gastric cancer through IL-8-linked regulation of the VEGF pathway.

Interleukin-8: A potent promoter of angiogenesis in gastric cancer

Angiogenesis is a critical process in the development of tumor malignancy and occurs at various stages of tumor progression. Interleukin-8 (IL-8) is a pro-angiogenic factor produced by tumor-infiltrating macrophages that has been revealed to facilitate the development of angiogenesis in various cancers. However, whether IL-8 activates angiogenesis in gastric cancer remains unclear. The present study investigated the effect of IL-8 on the migration and canalization capacities of human umbilical vein endothelial cells (HUVECs). In addition, the protein and messenger RNA (mRNA) expression of selected angiogenesis markers, consisting of vascular endothelial growth factor (VEGF)-A, VEGF receptor (VEGFR)-1 and VEGFR-2, were assessed in the HUVECs. The HUVECs were co-cultured with human gastric cancer SGC7901 cells and exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1.0 ng/ml). The migration and canalization abilities of the cells were detected by Transwell chamber and tube formation assays. Protein expression was detected using immunofluorescence and western blot analysis, and mRNA levels were assessed using reverse transcription quantitative polymerase chain reaction. The protein and mRNA levels of VEGF-A, VEGFR-1 and VEGFR-2 were measured in HUVECs cultured for 24 h. IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly promoted HUVEC cell migration (P=0.005, P=0.001 and P<0.001, respectively) and tube formation (P=0.039, P=0.003 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-A (P<0.001) and VEGFR-2 (P=0.034, P<0.001, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-1 (P=0.037 and P=0.002, respectively). Similarly, IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGF-A (P=0.046, P=0.001 and P<0.001, respectively) and VEGFR-1 (P=0.042, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGFR-2 (P=0.003, P=0.005, P<0.001 and P<0.001, respectively). In conclusion, IL-8 may be a potent promoter of angiogenesis in gastric cancer.