Anti-angiogenic effect of auranofin on HUVECs in vitro and zebrafish in vivo

Anticancer Activity of Metallodrugs and Metallizing Host Defense Peptides-Current Developments in Structure-Activity Relationship

This article provides an overview of the development, structure and activity of various metal complexes with anti-cancer activity. Chemical researchers continue to work on the development and synthesis of new molecules that could act as anti-tumor drugs to achieve more favorable therapies. It is therefore important to have information about the various chemotherapeutic substances and their mode of action. This review focuses on metallodrugs that contain a metal as a key structural fragment, with cisplatin paving the way for their chemotherapeutic application. The text also looks at ruthenium complexes, including the therapeutic applications of phosphorescent ruthenium(II) complexes, emphasizing their dual role in therapy and diagnostics. In addition, the antitumor activities of titanium and gold derivatives, their side effects, and ongoing research to improve their efficacy and reduce adverse effects are discussed. Metallization of host defense peptides (HDPs) with various metal ions is also highlighted as a strategy that significantly enhances their anticancer activity by broadening their mechanisms of action.

Tyrosine kinase inhibitors (TKIs) for ovarian cancer treatment: from organic to inorganic chemotherapeutics towards selectivity-a perspective overview

Ovarian cancer (OC) is a lethal gynecologic cancer in industrialized countries. Treatments for OC include the surgical removal and chemotherapy. In the last decades, improvements have been made in the surgery technologies, drug combinations and administration protocols, and in diagnosis. However, mortality from OC is still high owing to recurrences and insurgence of drug resistance. Accordingly, it is urgent the development of novel agents capable to effectively target OC. In this respect, tyrosine kinase inhibitors (TKIs) may play an important role. Most of TKIs developed and tested so far are organic. However, owing to their chemical versatility, also metals can be exploited to design selective and potent TKIs. We provide a short and easy-to-read overview on the main organic TKIs with a summary of those that entered clinical trials. Additionally, we describe the potential of metal-based TKIs, focusing on this overlooked family of compounds that may significantly contribute towards the concept of precision-medicine.

Revisiting the anticancer properties of phosphane(9-ribosylpurine-6-thiolato)gold(I) complexes and their 9H-purine precursors

New mono- and di-nuclear thio-purine and thio-purine nucleoside gold(I) complexes were synthesized, characterized, and evaluated in vitro for biological activities in comparison to related known purine complexes. By combining known anti-tumoral thio-purines with R₃PAu moieties as present in auranofin, complexes with enhanced effects and selectivities were obtained, which not only act as cytostatics, but also disrupt tumor-specific processes. Their IC₅₀ values in cytotoxicity test with tumor cell lines ranged from three-digit nanomolar to single-digit micromolar, revealing a tentative structure-activity relationship (SAR). Both the residues R² of the phosphane ligand and R¹ at C2 of the pyrimidine ring had a significant impact on the cytotoxicity. In most cases, the introduction of a ribo-furanosyl group at N9 of the purine led to a distinctly more cytotoxic complex. Most complexes were more active against multi-drug-resistant tumor cells or such lacking functional p53 when compared to the respective untreated wild type cell lines. Some nucleoside complexes displayed an interesting dose-dependent dual mode of action regarding cell cycle arrest and DNA repair mechanism. Some phosphane(purine-6-thiolato)gold (I) complexes had a stronger inhibitory effect on the thioredoxin reductase (TrxR) and on the reactive oxygen species (ROS) generation in cancer cells than is typical of other gold complexes. They also led to DNA fragmentation and showed anti-angiogenic effects. Their stability under test conditions was demonstrated by ⁷⁷Se NMR monitoring of an exemplary selenopurine complex.

The Effects on Angiogenesis of Relevant Inorganic Chemotherapeutics

Angiogenesis is a key process allowing the formation of blood vessels. It is crucial for all the tissues and organs, ensuring their function and growth. Angiogenesis is finely controlled by several mechanisms involving complex interactions between pro- or antiangiogenic factors, and an imbalance in this control chain may result in pathological conditions. Metals as copper, zinc and iron cover an essential role in regulating angiogenesis, thus therapies having physiological metals as target have been proposed. In addition, some complexes of heavier metal ions (e.g., Pt, Au, Ru) are currently used as established or experimental anticancer agents targeting genomic or non-genomic targets. These molecules may affect the angiogenic mechanisms determining different effects that have been only poorly and non-systematically investigated so far. Accordingly, in this review article, we aim to recapitulate the impact on the angiogenic process of some reference anticancer drugs, and how it is connected to the overall pharmacological effects. In addition, we highlight how the activity of these drugs can be related to the role of biological essential metal ions. Overall, this may allow a deeper description and understanding of the antineoplastic activity of both approved or experimental metal complexes, providing important insights for the synthesis of new inorganic drugs able to overcome resistance and recurrence phenomena.

Design and synthesis of novel celastrol derivative and its antitumor activity in hepatoma cells and antiangiogenic activity in zebrafish

Two series of celastrol derivatives were designed and synthesized by modifying carboxylic acid at the 28th position with amino acid, and their intermediates with isobutyrate at the third position. All compounds were evaluated for their antiproliferation activity by four human cancer cell lines (SCG7901, HGC27, HepG2, and Bel7402) and one normal cell LO2. The most promising compound, compound 8, showed superior bioactivity and lower toxicity than others including celastrol. Further underlying tests illustrated that compound 8 induced apoptosis and cell arrest at G2/M and inhibited proliferation and mobility of human hepatoma cells by suppressing the signal transducer and activator of transcription-3 signaling pathway. Besides these, a highly accurate and reproducible high performance liquid chromatography protocol was established to determine celastrol and compound 8 absorption in zebrafish, and results demonstrated that their concentration increased rapidly within 4 hr in a time-dependent manner and the concentration of compound 8 was higher than that of celastrol. In addition, without detection at 12 hr, compound 8 was rapidly metabolized in vivo. These findings are very helpful for the structural modification of celastrol and other bioactive compounds to improve their bioactivity, toxicity, and absorption.

1-Methoxycarbony-β-carboline from Picrasma quassioides exerts anti-angiogenic properties in HUVECs in vitro and zebrafish embryos in vivo

Angiogenesis is a crucial process in the development of inflammatory diseases, including cancer, psoriasis and rheumatoid arthritis. Recently, several alkaloids from Picrasma quassioides had been screened for angiogenic activity in the zebrafish model, and the results indicated that 1-methoxycarbony-β-carboline (MCC) could effectively inhibit blood vessel formation. In this study, we further confirmed that MCC can inhibit, in a concentration-dependent manner, the viability, migration, invasion, and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro, as well as the regenerative vascular outgrowth of zebrafish caudal fin in vivo. In the zebrafish xenograft assay, MCC inhibited the growth of tumor masses and the metastatic transplanted DU145 tumor cells. The proteome profile array of the MCC-treated HUVECs showed that MCC could down-regulate several angiogenesis-related self-secreted proteins, including ANG, EGF, bFGF, GRO, IGF-1, PLG and MMP-1. In addition, the expression of two key membrane receptor proteins in angiogenesis, TIE-2 and uPAR, were also down-regulated after MCC treatment. Taken together, these results shed light on the potential therapeutic application of MCC as a potent natural angiogenesis inhibitor via multiple molecular targets.

Mononuclear gold(iii) complexes with l-histidine-containing dipeptides: tuning the structural and biological properties by variation of the N-terminal amino acid and counter anion

Gold(iii) complexes with different l-histidine-containing dipeptides, [Au(Gly-l-His-N_A,N_P,N3)Cl]Cl·3H₂O (1a), [Au(Gly-l-His-N_A,N_P,N3)Cl]NO₃·1.25H₂O (1b), [Au(l-Ala-l-His-N_A,N_P,N3)Cl][AuCl₄]·H₂O (2a), [Au(l-Ala-l-His-N_A,N_P,N3)Cl]NO₃·2.5H₂O (2b), [Au(l-Val-l-His-N_A,N_P,N3)Cl]Cl·2H₂O (3), [Au(l-Leu-l-His-N_A,N_P,N3)Cl]Cl (4a) and [Au(l-Leu-l-His-N_A,N_P,N3)Cl][AuCl₄]·H₂O (4b), have been synthesized and structurally characterized by spectroscopic (¹H NMR, IR and UV-vis) and single-crystal X-ray diffraction techniques. The antimicrobial efficiency of these gold(iii) complexes, along with K[AuCl₄] and the corresponding dipeptides, was evaluated against the broad panel of Gram-positive and Gram-negative bacteria and fungi, displaying their moderate inhibiting activity. Moreover, the cytotoxic properties of the investigated complexes were assessed against the normal human lung fibroblast cell line (MRC5) and two human cancer, cervix (HeLa) and lung (A549) cell lines. None of the complexes exerted significant cytotoxic activity; nevertheless complexes that did show selectivity in terms of cancer vs. normal cell lines (2a/b and 4a/b) have been evaluated using zebrafish (Danio rerio) embryos for toxicity and antiangiogenic potential. Although the gold(iii) complexes achieved an antiangiogenic effect comparable to the known angiogenic inhibitors auranofin and sunitinib malate at 30-fold higher concentrations, they had no cardiovascular side effects, which commonly accompany auranofin and sunitinib malate treatment. Finally, binding of the gold(iii) complexes to the active sites of both human and bacterial (Escherichia coli) thioredoxin reductases (TrxRs) was demonstrated by conducting a molecular docking study, suggesting that the mechanism of biological action of these complexes can be associated with their interaction with the TrxR active site.

A heterometallic ruthenium-gold complex displays antiproliferative, antimigratory, and antiangiogenic properties and inhibits metastasis and angiogenesis-associated proteases in renal cancer

Heterobimetallic compounds are designed to harness chemotherapeutic traits of distinct metal species into a single molecule. The ruthenium-gold (Ru-Au) family of compounds based on Au-N-heterocyclic carbene (NHC) fragments [Cl2(p-cymene)Ru(μ-dppm)Au(NHC)]ClO4 was conceived to combine the known antiproliferative and cytotoxic properties of Au-NHC-based compounds and the antimigratory, antimetastatic, and antiangiogenic characteristic of specific Ru-based compounds. Following recent studies of the anticancer efficacies of these Ru-Au-NHC complexes with promising potential as chemotherapeutics against colorectal, and renal cancers in vitro, we report here on the mechanism of a selected compound, [Cl2(p-cymene)Ru(μ-dppm)Au(IMes)]ClO4 (RANCE-1, 1). The studies were carried out in vitro using a human clear cell renal carcinoma cell line (Caki-1). These studies indicate that bimetallic compound RANCE-1 (1) is significantly more cytotoxic than the Ru (2) or Au (3) monometallic derivatives. RANCE-1 significantly inhibits migration, invasion, and angiogenesis, which are essential for metastasis. RANCE-1 was found to disturb pericellular proteolysis by inhibiting cathepsins, and the metalloproteases MMP and ADAM which play key roles in the etiopathogenesis of cancer. RANCE-1 also inhibits the mitochondrial protein TrxR that is often overexpressed in cancer cells and facilitates apoptosis evasion. We found that while auranofin perturbed migration and invasion to similar degrees as RANCE-1 (1) in Caki-1 renal cancer cells, RANCE-1 (1) inhibited antiangiogenic formation and VEGF expression. We found that auranofin and RANCE-1 (1) have distinct proteolytic profiles. In summary, RANCE-1 constitutes a very promising candidate for further preclinical evaluations in renal cancer.

Endothelial Dysfunction and Inflammation: Immunity in Rheumatoid Arthritis

Inflammation, as a feature of rheumatoid arthritis (RA), leads to the activation of endothelial cells (ECs). Activated ECs induce atherosclerosis through an increased expression of leukocyte adhesion molecules. Endothelial dysfunction (ED) is recognized as a failure of endothelial repair mechanisms. It is also an early preclinical marker of atherosclerosis and is commonly found in RA patients. RA is now established as an independent cardiovascular risk factor, while mechanistic determinants of ED in RA are still poorly understood. An expanding body of study has shown that EC at a site of RA is both active participant and regulator of inflammatory process. Over the last decade, a role for endothelial dysfunction in RA associated with cardiovascular disease (CVD) has been hypothesized. At the same time, several maintenance drugs targeting this phenomenon have been tested, which has promising results. Assessment of endothelial function may be a useful tool to identify and monitor RA patients.

Kaempferol induces ATM/p53-mediated death receptor and mitochondrial apoptosis in human umbilical vein endothelial cells

Kaempferol is a member of the flavonoid compounds found in vegetables and fruits. It is shown to exhibit biological impact and anticancer activity, but no report exists on the angiogenic effect of kaempferol and induction of cell apoptosis in vitro. In this study, we investigated the role of kaempferol on anti-angiogenic property and the apoptotic mechanism of human umbilical vein endothelial cells (HUVECs). Our results demonstrated that kaempferol decreased HUVEC viability in a time- and concentration-dependent manner. Kaempferol also induced morphological changes and sub-G1 phase cell population (apoptotic cells). Kaempferol triggered apoptosis of HUVECs as detecting by DNA fragmentation, comet assay and immunofluorescent staining for activated caspase-3. The caspase signals, including caspase-8, -9 and -3, were time-dependently activated in HUVECs after kaempferol exposure. Furthermore, pre-treatment with a specific inhibitor of caspase-8 (Z-IETD-FMK) significantly reduced the activity of caspase-8, -9 and -3, indicating that extrinsic pathway is a major signaling pathway in kaempferol-treated HUVECs. Importantly, kaempferol promoted reactive oxygen species (ROS) evaluated using flow cytometric assay in HUVECs. We further investigated the upstream extrinsic pathway and showed that kaempferol stimulated death receptor signals [Fas/CD95, death receptor 4 (DR4) and DR5] through increasing the levels of phosphorylated p53 and phosphorylated ATM pathways in HUVECs, which can be individually confirmed by N-acetylcysteine (NAC), ATM specific inhibitor (caffeine) and p53 siRNA. Based on these results, kaempferol-induced HUVEC apoptosis was involved in an ROS-mediated p53/ATM/death receptor signaling. Kaempferol might possess therapeutic effects on cancer treatment in anti-vascular targeting.

In vivo SAR and STR analyses of alkaloids from Picrasma quassioides identify 1-hydroxymethyl-8-hydroxy-β-carboline as a novel natural angiogenesis inhibitor

Twenty alkaloids were obtained from the anti-angiogenic fraction of Picrasma quassioides and their SAR/STR were studies by a zebrafish model. We had identified 3 as an angiogenesis inhibitor and confirmed in vitro.

Microvessels Density in Uterine Leiomyosarcoma

Uterine leiomyosarcomas (LMS) are rare tumors typically presenting rapid growth and unfavorable outcome. Nowadays the results of uterine LMS treatment do not meet expectations. Angiogenesis is one of processes investigated to be target for future treatment. The aim of the research was to assess microvessels density (MVD) in tumor samples collected from 50 patients with histological confirmed uterine leiomyosarcoma and to investigate statistical relations between MVD, patients survival, and FIGO stage of tumor. The assessment was carried out using immunohistochemistry methods with anti-CD34 antibody. No significant difference in MVD between FIGO stages was observed. Furthermore, contrary to many other malignancies, we found no significant relation between MVD and patients overall and 2-year survival. Results obtained in the study suggest that processes on vascular mimicry and mesenchymal to epithelial transition (MET) may play important role in development of LMS. No statistical relation between MVD and survival leads to conclusion that not only angiogenesis but other mechanisms as well should be taken into consideration in planning future research.

Green synthesis of reduced graphene oxide by a GRAS strain Bacillus subtilis 168 with high biocompatibility to zebrafish embryos

A low toxic and highly biocompatible bacterially reduced graphene oxide was prepared by a “Generally Recognized As Safe” strain Bacillus subtilis 168 mediated with Vitamin K₃.