Plant cystine-knot peptides: pharmacological perspectives

Cystine-knot miniproteins are a class of 30-50 amino acid long peptides widespread in eukaryotic organisms. Due to their very peculiar three-dimensional structure, they exhibit high resistance to heat and peptidase attack. The cystine-knot peptides are well represented in several plant species including medicinal herbs and crops. The pharmacological interest in plant cystine-knot peptides derives from their broad biological activities, mainly cytotoxic, antimicrobial and peptidase inhibitory and in the possibility to engineer them to incorporate pharmacophoric information for oral delivery or disease biomonitoring. The mechanisms of action of plant cystine-knot peptides are still largely unknown, although the capacity to interfere with plasma membranes seems a feature common to several cystine-knot peptides. In some cases, such as potato carboxypetidase inhibitor (PCI) and tomato cystine-knot miniproteins (TCMPs), the cystine-knot peptides target human growth factor receptors either by acting as growth factor antagonist or by altering their signal transduction pathway. The possibility to identify specific molecular targets of plant cystine-knot peptides in human cells opens novel possibilities for the pharmacological use of these peptides besides their use as scaffold to develop stable disease molecular markers and therapeutic agents.

Renal thrombotic microangiopathy caused by interferon beta-1a treatment for multiple sclerosis

Interferon beta-1a is available as an immunomodulating agent for relapsing forms of multiple sclerosis. Common side effects include flu-like symptoms, asthenia, anorexia, and administration site reaction. Kidney disorders are rarely reported. In this study we describe the case of a woman who has been undergoing treatment with interferon beta-1a for multiple sclerosis for 5 years. She developed a hemolytic-uremic syndrome with intravascular hemolysis in a context of severe hypertension. A kidney biopsy showed a thrombotic microangiopathy. This observation highlights an uncommon side effect of long-term interferon beta-1a therapy. Pathophysiological mechanisms leading to this complication might be explained by the antiangiogenic activity of interferon.

Alveolar soft-part sarcoma responding to interferon alpha-2b

A 23-year-old woman with an alveolar soft-part sarcoma of her calf with pulmonary metastases unresponsive to chemotherapy is described. Interferon (IFN) alpha-2b induced an impressive tumour response still ongoing after IFN treatment had to be stopped because of a psychosis. An explanation of this effect is still speculative.

Antiangiogenic polyketides from Peperomia dindygulensis Miq

Two new polyketides: 2Z-(heptadec-12-enyl)-4-hydroxy-3,4,7,8-tetrahydro-2H-chromen-5(6H)-one (1) and 2-(heptadec-12-enyl)-5-hydroxy-5,6,7,8-tetrahydrochromen- 4-one (2), together with eleven known compounds: 4-hydroxy-2-[(3,4-methylenedioxy- phenyl)tridecanoyl] cyclohexane-1,3-dione (3), oleiferinone (4), 4-hydroxy-2-[(3,4- methylenedioxyphenyl)undecanoyl]cyclohexane-1,3-dione (5), 4-hydroxy-2-[(11-phenyl- undecanoyl)cyclohexane-1,3-dione (6), proctorione C (7), surinone C (8), 5-hydroxy- 7,8,4'-trimethoxyflavone (9), 5-hydroxy-7,8,3',4'-tetramethoxyflavone (10), 5-hydroxy- 7,3',4'-trimethoxyflavone (11), 5,8-dihydroxy-7,3',4'-trimethoxyflavone (12) and cepharanone B (13) were isolated from the whole plant of Peperomia dindygulensis Miq. Their structures were elucidated by spectroscopic methods, including 2D-NMR techniques. Compounds 2, 3, 5 and 8 inhibited human umbilical vein endothelial cell (HUVEC) proliferation and compounds 5 and 8 sharply suppressed HUVEC tube formation.

Lipophilization of somatostatin analog RC-160 with long chain fatty acid improves its antiproliferative and antiangiogenic activity in vitro

The therapeutic potential of the somatostatin analogue RC-160 having antiproliferative activity, is limited by its short serum half life. To overcome this limitation, fatty acids namely butanoic acid and myristic acid were conjugated to the N-terminal residue of RC-160. The lipophilized derivatives of RC-160 were synthesized, purified by reverse phase HPLC and characterized by ES-mass spectroscopy. The antiproliferative activity of lipophilized derivatives of RC-160 on the growth of MIA-PaCa2 (human pancreatic carcinoma), DU145 (human prostate carcinoma), ECV304 (human umbilical chord endothelioma), as well as their antiangiogenic activity was evaluated in vitro. The relative stability of myristoyl-RC-160 towards degradation by proteases and serum was also determined. Myristoyl-RC-160 exhibited significantly higher antiproliferative efficacy than RC-160, on the above cell lines (P<0.01). Receptor binding assays, demonstrated that the affinity of RC-160 towards somatostatin receptors remains unaltered by myristoylation. Unlike RC-160, the myristoylated derivative was found to have significantly greater resistance to protease and serum degradation (P<0.01). Myristoyl-RC-160 exhibited significantly greater antiproliferative activity on ECV304, than RC-160 (P<0.01). Myristoyl RC-160 could also inhibit capillary tube formation more efficiently than RC-160 in a dose dependent manner, suggesting that it possessed enhanced antiangiogenic activity in vitro (P<0.001). Lipophilization of RC-160 with long chain fatty acids like myristic acid endows it with improved antiproliferative and antiangiogenic activity, stability and therapeutic index. British Journal of Pharmacology (2000) 109, 101 - 109

Ten Years of Research on Fucoidan and Cancer: Focus on Its Antiangiogenic and Antimetastatic Effects

Angiogenesis and metastasis represent two challenging targets to combat cancer development in the later stages of its progression. Numerous studies have indicated the important role of natural products in blocking tumor angiogenesis signaling pathways in several advanced tumors. In recent years, the marine polysaccharides fucoidans emerged as promising anticancer compounds showing potent antitumor activity in both in vitro and in vivo models of different types of cancers. The objective of this review is to focus on the antiangiogenic and antimetastatic activities of fucoidans with special emphasis on preclinical studies. Independently from their source, fucoidans inhibit several angiogenic regulators, primarily vascular endothelial growth factor (VEGF). A glance towards fucoidans' ongoing clinical trials and pharmacokinetic profile is provided to present the main challenges that still need to be addressed for their bench-to-bedside translation.

A Catechol-Type Resveratrol Analog Manifests Antiangiogenic Action by Constructing an Efficient Catalytic Redox Cycle with Intracellular Copper Ions and NQO1

SCOPE

As part of our research project to understand why dietary polyphenols with the catechol skeleton tend to exhibit cancer chemopreventive activity, a catechol-type resveratrol analog (3,4-dihydroxy-trans-stilbene [3,4-DHS]) was selected to probe its antiangiogenic effects and mechanisms.

METHODS AND RESULTS

The antiangiogenic effects of 3,4-DHS on angiogenesis-related endothelial cell functions were examined, including migration, invasion, and tube formation, and in vivo angiogenesis on a chick chorioallantoic membrane assay. The potential molecular mechanisms for the suppression of cell migration by 3,4-DHS were analyzed using various specific inhibitors. 3,4-DHS was identified as a potent angiogenesis inhibitor by constructing an efficient catalytic redox cycle with intracellular copper ions and NAD(P)H quinone oxidoreductase I to generate reactive oxygen species and thereby downregulate matrix metalloproteinase-9.

CONCLUSION

This work provides further evidence that dietary catechols manifest antiangiogenic activity by virtue of their copper-dependent prooxidative instead of antioxidative role, and useful information for designing polyphenol-inspired angiogenesis inhibitors.

A potential use of a synthetic retinoid TAC-101 as an orally active agent that blocks angiogenesis in liver metastases of human stomach cancer cells

TAC-101 (4-[3,5-bis(trimethylsilyl)benzamido]benzoic acid) is a novel, synthetic retinoid that is effective against liver metastases of human gastrointestinal cancer cells such as the human stomach carcinoma line AZ-521 in animal models, and is currently in use in phase I cancer trials. However, the mechanism of its antimetastatic action is still poorly understood. Tumor metastasis depends on angiogenesis, and various retinoids have been found to exhibit antiangiogenic activity. Based on these findings we here examined the antiangiogenic effects of TAC-101. Oral administration of TAC-101 (2-8 mg/kg/day) resulted in a drastic suppression of the AZ-521 cell-induced angiogenesis in a mouse dorsal air sac assay system, compared to the vehicle alone. Immunohistochemical analysis with antibody against the endothelial marker CD31 revealed a significant reduction in microvessel density in liver metastases from animals treated with TAC-101 (8 mg/kg p.o.), compared to liver metastases from the untreated control animals. The ability of TAC-101 (8 mg/kg p.o.) to prevent experimental liver metastasis of AZ-521 cells in athymic nude mice was comparable with that of the known angiogenesis inhibitor TNP-470 (30 mg/kg s.c.). TAC-101 also affected angiogenesis in chorioallantoic membranes and some functions of endothelial cells associated with angiogenesis, whereas the retinoid failed to suppress AZ-521 cell proliferation directly. These data suggest that the TAC-101 is an orally active antiangiogenic agent and that this antiangiogenic property may contribute to its efficacy against liver metastasis of human stomach cancer cells.

Enzymatic activity of free-prostate-specific antigen (f-PSA) is not required for some of its physiological activities

BACKGROUND

Prostate specific antigen (PSA) is a well known biomarker for early diagnosis and management of prostate cancer. Furthermore, PSA has been documented to have anti-angiogenic and anti-tumorigenic activities in both in vitro and in vivo studies. However, little is known about the molecular mechanism(s) involved in regulation of these processes, in particular the role of the serine-protease enzymatic activity of PSA.

METHODS

Enzymatic activity of PSA isolated directly from seminal plasma was inhibited specifically (>95%) by incubation with zinc2+ . Human umbilical vein endothelial cells (HUVEC) were utilized to compare/contrast the physiological effects of enzymatically active versus inactive PSA.

RESULTS

Equimolar concentrations of enzymatically active PSA and PSA enzymatically inactivated by incubation with Zn2+ had similar physiological effects on HUVEC, including inhibiting the gene expression of pro-angiogenic growth factors, like VEGF and bFGF, and up-regulation of expression of the anti-angiogenic growth factor IFN-γ; suppression of mRNA expression for markers of blood vessel development, like FAK, FLT, KDR, TWIST-1; P-38; inhibition of endothelial tube formation in the in vitro Matrigel Tube Formation Assay; and inhibition of endothelial cell invasion and migration properties.

DISCUSSION

Our data provides compelling evidence that the transcriptional regulatory and the anti-angiogenic activities of human PSA are independent of the innate enzymatic activity.

Chemical constituents from Munronia sinica and their bioactivities

Two new minor constituents, musinisins A (1) and B (2), together with five known compounds (3–7), were isolated from the aerial parts of Munronia sinica. Their structures were established by means of spectroscopic methods and the absolute stereochemistry of 1 was determined by single crystal X-ray experiment. Compound 4 showed antiangiogenic activity evaluated by a zebrafish model and apoptosis-inducing effect on A549 lung cancer cells.

Avian Reovirus P17 Suppresses Angiogenesis by Promoting DPP4 Secretion

Avian reovirus p17 (ARV p17) is a non-structural protein known to activate autophagy, interfere with gene transcription and induce a significant tumor cell growth inhibition in vitro and in vivo. In this study, we show that ARV p17 is capable of exerting potent antiangiogenic properties. The viral protein significantly inhibited the physiological angiogenesis of human endothelial cells (ECs) by affecting migration, capillary-like structure and new vessel formation. ARV p17 was not only able to suppress the EC physiological angiogenesis but also rendered ECs insensitive to two different potent proangiogenic inducers, such as VEGF-A and FGF-2 in the three-dimensional (3D) Matrigel and spheroid assay. ARV p17 was found to exert its antiangiogenic activity by upregulating transcription and release of the well-known tumor suppressor molecule dipeptidyl peptidase 4 (DPP4). The ability of ARV p17 to impact on angiogenesis is completely new and highlights the “two compartments” activity of the viral protein that is expected to hamper the tumor parenchymal/stromal crosstalk. The complex antitumor activities of ARV p17 open the way to a new promising field of research aimed to develop new therapeutic approaches for treating tumor and cancer metastasis.

Antiangiogenic properties of substituted (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol/one analogs and their derivatives

In the past half century research efforts have defined a critical role for angiogenesis in tumor growth and metastasis. We previously reported that inhibition of a novel target, ENOX1, by a (Z)-2-benzylindol-3-ylmethylene) quinuclidin-3-ol, suppressed tumor angiogenesis. The present study was undertaken in order to establish structure-activity relationships for quinuclidine analogs. The angiogenesis inhibiting activity of a series of substituted (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ols (1a-1k), (Z)-2-benzylindol-3-ylmethylene)quinuclidin-3-ones (2a-2h), (Z)-(±)-2-(1H/N-methyl-indol-3-ylmethylene)quinuclidin-3-ols (3a-3b), and substituted (Z)-(±)-2-(N-benzenesulfonylindol-3-yl-methylene)quinuclidin-3-ols and their derivatives (4a-4d) that incorporate a variety of substituents in both the indole and N-benzyl moieties was evaluated using Human Umbilical Vein Endothelial Cells (HUVECs) subjected to in vitro cell migration scratch assays, tubule formation in Matrigel, cell viability and proliferation assays. In total, 25 different analogs were evaluated. Based on in vitro cell migration scratch assays, eight analogs were identified as potent angiogenesis inhibitors at 10 μM, a concentration that was determined to be nontoxic by colony formation assay. In addition, this approach identified a potent antiangiogenic ENOX1 inhibitor, analog 4b.

Controlled Release of Caffeic Acid and Pinocembrin by Use of nPSi-βCD Composites Improves Their Antiangiogenic Activity

Although polyphenols have great pharmacological potential, the main disadvantage is that they have low bioavailability at the desired site. Thus, the use of biocompatible systems for drug delivery is a strategy that is currently gaining great interest. The objective of this study is to evaluate the effect of microencapsulation of caffeic acid and pinocembrin on the antioxidant and antiangiogenic activity of both polyphenols, by the use of nPSi-βCD composite microparticles. For this HUVEC, cells were exposed to H₂O₂ and to treatments with polyphenols in solution and loaded in the composite microparticle. The polyphenols were incorporated into a microparticle using nanoporous silicon, chitosan and a β-cyclodextrin polymer as the biomaterial. The evaluation of the antiangiogenic effect of the treatments with polyphenols in solution and microencapsulated was carried out through functional tests, and the changes in the expression of target genes associated with the antioxidant pathway and angiogenesis was performed through qPCR. The results obtained show that the caffeic acid and pinocembrin have an antioxidant and antiangiogenic activity, both in solution as microencapsulated. In the caffeic acid, a greater biological effect was observed when it was incorporated into the nPSi-βCD composite microparticle. Our results suggest that the nPSi-βCD composite microparticle could be used as an alternative oral drug administration system.

Hyalomma dromedarii (Acari: Ixodidae) Salivary Gland Extract Inhibits Angiogenesis and Exhibits In Vitro Antitumor Effects

Hard ticks (Acari: Ixodidae) are blood-sucking ectoparasites characterized by the extended period of their attachment to their host. To access their bloodmeal, ticks secrete saliva containing a range of molecules that target the host's inflammation, immune system, and hemostatic components. Some of these molecules reportedly possess antiangiogenic and antitumor properties. The present study describes our investigation, the first of its kind, of the antiangiogenic and antitumoral effects of the Hyalomma dromedarii Koch, 1844 (Acari: Ixodidae), salivary gland extract (SGE), which inhibited the adhesion and migration of Human Umbilical Vein Endothelial Cells (HUVECs) in a dose-dependent manner, as well as angiogenesis in the Chick Chorioallantoic Membrane model. Interestingly, H. dromedarii SGE exerted an antiproliferative effect on U87 glioblastoma cells and inhibited their adhesion and migration to fibrinogen. These results open up new possibilities for characterizing and developing new molecules involved in the key steps of tumor progression.

Characterization and In Vivo Antiangiogenic Activity Evaluation of Morin-Based Cyclodextrin Inclusion Complexes

Morin (MRN) is a natural compound with antiangiogenic, antioxidant, anti-inflammatory, and anticancer activity. However, it shows a very low water solubility (28 μg/mL) that reduces its oral absorption, making bioavailability low and unpredictable. To improve MRN solubility and positively affect its biological activity, particularly its antiangiogenic activity, in this work, we prepared the inclusion complexes of MNR with sulfobutylether-β-cyclodextrin (SBE-β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD). The inclusion complexes obtained by the freeze-drying method were extensively characterized in solution (phase-solubility studies, UV-Vis titration, and NMR spectroscopy) and in the solid state (TGA, DSC, and WAXD analysis). The complexation significantly increased the water solubility by about 100 times for MRN/HP-β-CD and 115 times for MRN/SBE-β-CD. Furthermore, quantitative dissolution of the complexes was observed within 60 min, whilst 1% of the free drug dissolved in the same experimental time. 1H NMR and UV-Vis titration studies demonstrated both CDs well include the benzoyl moiety of the drug. Additionally, SBE-β-CD could interact with the cinnamoyl moiety of MRN too. The complexes are stable in solution, showing a high value of association constant, that is, 3380 M-1 for MRN/HP-β-CD and 2870 M-1 for MRN/SBE-β-CD. In vivo biological studies on chick embryo chorioallantoic membrane (CAM) and zebrafish embryo models demonstrated the high biocompatibility of the inclusion complexes and the effective increase in antiangiogenic activity of complexed MRN with respect to the free drug.

Salprzesides A and B: two novel icetexane diterpenes with antiangiogenic activity from Salvia przewalskii Maxim

Two novel icetexane diterpenes were isolated from Salvia przewalskii Maxim., namely Salprzesides A (1) and B (2), together with two known abietane-type diterpenes respectively identified as sahandinone (3) and miltirone (4). The structures of isolated compounds were determined by UV, IR, HR-ESI-MS, 1D and 2D NMR analysis. The in vitro antiangiogenic activities of compounds 1-4 were studied against human umbilical vascular endothelial cells (HUVECs). The IC₅₀ values of compounds 1-4 ranged from 4.22 ± 1.07 to 39.31 ± 2.17 μM against HUVECs.

Effect of the Marine Polyketide Plocabulin on Tumor Progression

Marine sponges represent one of the richest sources of natural marine compounds with anticancer potential. Plocabulin (PM060184), a polyketide originally isolated from the sponge Lithoplocamia lithistoides, elicits its main anticancer properties binding tubulin, which still represents one of the most important targets for anticancer drugs. Plocabulin showed potent antitumor activity, in both in vitro and in vivo models of different types of cancers, mediated not only by its antitubulin activity, but also by its ability to block endothelial cell migration and invasion. The objective of this review is to offer a description of plocabulin's mechanisms of action, with special emphasis on the antiangiogenic signals and the latest progress on its development as an anticancer agent.

Antiproliferative, Antioxidant, Chemopreventive and Antiangiogenic Potential of Chromatographic Fractions from Anemonia sulcata with and without Its Symbiont Symbiodinium in Colorectal Cancer Therapy

Anemonia sulcata may be a source of marine natural products (MNPs) due to the antioxidant and antitumor activity of its crude homogenates shown in vitro in colon cancer cells. A bioguided chromatographic fractionation assay of crude Anemonia sulcata homogenates with and without its symbiont Symbiodinium was performed to characterize their bioactive composition and further determine their biological potential for the management of colorectal cancer (CRC). The 20% fractions retained the in vitro antioxidant activity previously reported for homogenates. As such, activation of antioxidant and detoxifying enzymes was also evaluated. The 40% fractions showed the greatest antiproliferative activity in T84 cells, synergistic effects with 5-fluoruracil and oxaliplatin, overexpression of apoptosis-related proteins, cytotoxicity on tumorspheres, and antiangiogenic activity. The predominantly polar lipids and toxins tentatively identified in the 20% and 40% fractions could be related to their biological activity in colon cancer cells although further characterizations of the active fractions are necessary to isolate and purify the bioactive compounds.

Hyperipersions A-C, three new acylphloroglucinols from the branches and leaves of Hypericum perforatum L. with antiangiogenic activities

Three new acylphloroglucinols were isolated from the branches and leaves of Hypericum perforatum L., named as hyperipersions A-C (1-3), together with three known compounds which were identified as elegaphenone (4), 2,6-dihydroxy-3,4-dimethylbenzoic acid methyl ester (5) and 2,3-methylenedioxyxanthone (6), respectively. The structures of isolated compounds were determined by UV, IR, HR-ESI-MS, NMR analysis. Their antiangiogenic activities were studied against HUVECs. The IC50 value of compound 3 was 2.39 ± 0.21 μM against HUVECs, which was stronger than vatalanib, and other compounds had moderate antiangiogenic activity.

A multifaceted assessment of strigolactone GR24 and its derivatives: from anticancer and antidiabetic activities to antioxidant capacity and beyond

Background: Strigolactones are signaling molecules produced by plants, the main functions are the intracorporeal control of plant development and plant growth. GR24 strigolactone is one of the synthetic strigolactones and due to its universality and easy availability, it is a standard and model compound for research on the properties and role of strigolactones in human health. Purpose: In this research work, the impact of mainly GR24 strigolactone on the human body and the role of this strigol-type lactone in many processes that take place within the human body are reviewed. Study design: The article is a review of publications on the use of GR24 strigolactone in studies from 2010-2023. Publications were searched using PubMed, Elsevier, Frontiers, and Springer databases. The Google Scholar search engine was also used. For the review original research papers and reviews related to the presented topic were selected. Results: The promising properties of GR24 and other strigolactone analogs in anti-cancer therapy are presented. Tumor development is associated with increased angiogenesis. Strigolactones have been shown to inhibit angiogenesis, which may enhance the anticancer effect of these γ-lactones. Furthermore, it has been shown that strigolactones have anti-inflammatory and antioxidant properties. There are also a few reports which show that the strigolactone analog may have antimicrobial and antiviral activity against human pathogens. Conclusion: When all of this is considered, strigolactones are molecules whose versatile action is their undeniable advantage. The development of research on these phytohormones makes it possible to discover their new, unique properties and surprising biological activities in relation to many mammalian cells.