Copper(II) Complexes Containing Natural Flavonoid Pomiferin Show Considerable In Vitro Cytotoxicity and Anti-inflammatory Effects

A series of new heteroleptic copper(II) complexes of the composition [Cu(L)(bpy)]NO₃·2MeOH (1), [Cu(L)(dimebpy)]NO₃·2H₂O (2), [Cu(L)(phen)]NO₃·2MeOH (3), [Cu(L)(bphen)]NO₃·MeOH (4), [Cu(L)(dppz)]NO₃·MeOH (5) was prepared, where HL = 3-(3,4-dihydroxyphenyl)-5-hydroxy-8,8-dimethyl-6-(3-methylbut-2-ene-1-yl)-4H,8H-benzo[1,2-b:3,4-b′]dipyran-4-one, (pomiferin) and bpy = 2,2′-bipyridine, dimebpy = 4,4′-dimethyl-2,2′-bipyridine, phen = 1,10-phenanthroline, bphen = 4,7-diphenyl-1,10-phenanthroline, and dppz = dipyrido[3,2-a:2′,3′-c]phenazine. The complexes were characterized using elemental analysis, infrared and UV/Vis spectroscopies, mass spectrometry, thermal analysis and conductivity measurements. The in vitro cytotoxicity, screened against eight human cancer cell lines (breast adenocarcinoma (MCF-7), osteosarcoma (HOS), lung adenocarcinoma (A549), prostate adenocarcinoma (PC-3), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), colorectal adenocarcinoma (Caco-2) and monocytic leukemia (THP-1), revealed the complexes as effective antiproliferative agents, with the IC₅₀ values of 2.2–13.0 μM for the best performing complexes 3 and 5. All the complexes 1–5 showed the best activity against the A2780R cells (IC₅₀ = 2.2–6.6 μM), and moreover, the complexes demonstrated relatively low toxicity on healthy human hepatocytes, with IC₅₀ > 100 μM. The complexes were evaluated by the Annexin V/propidium iodide apoptosis assay, induction of cell cycle modifications in A2780 cells, production of reactive oxygen species (ROS), perturbation of mitochondrial membrane potential, inhibition of apoptosis and inflammation-related signaling pathways (NF-κB/AP-1 activity, NF-κB translocation, TNF-α secretion), and tested for nuclease mimicking activity. The obtained results revealed the corresponding complexes to be effective antiproliferative and anti-inflammatory agents.     

Synthesis, characterization and antitumor activity of a series of polypyridyl complexes

A series of polypyridyl complexes have been synthesized. All polypyridyl complexes and some of the soluble ligands have been assayed for antitumor activity in vitro against the HL-60 (the human leucocytoma) cells, BEL-7402 (the human liver carcinoma) cells, KB (the human nasopharyngeal carcinoma) cells and HELA (the human adenocarcinoma of cervix) cells. The results indicate that several complexes have relative activity against different cell lines. Especially, the complexes [Co(bpy)(2)(pip)](3+), [Co(phen)(2)(pip)](3+), [Ru(bpy)(2)(pztp)](2+) and [Ru(pztp)(2)(bpy)](2+) show relative high activity against four tumor cell lines. Moreover, they are slightly more effective than cisplatin. At the concentration of 100 mug/mL, the complexes show inhibitory rate of 72 approximately 86% for the cancer cells and have no toxicity for MDCK and Vero cells. It is indicated that these complexes can inhibit cancer cells selectively.     

Anticancer Organometallic Osmium(II)‐p‐cymene Complexes

Osmium compounds are attracting increasing attention as potential anticancer drugs. In this context, a series of bifunctional organometallic osmium(II)‐p‐cymene complexes functionalized with alkyl or perfluoroalkyl groups were prepared and screened for their antiproliferative activity. Three compounds from the series display selectivity toward cancer cells, with moderate cytotoxicity observed against human ovarian carcinoma (A2780) cells, whereas no cytotoxicity was observed on non‐cancerous human embryonic kidney (HEK‐293) cells and human endothelial (ECRF24) cells. Two of these three cancer‐cell‐selective compounds induce cell death largely via apoptosis and were also found to disrupt vascularization in the chicken embryo chorioallantoic membrane (CAM) model. Based on these promising properties, these compounds have potential clinical applications.     

Preclinical Anticancer Activity of an Electron-Deficient Organoruthenium(II) Complex

Ruthenium compounds have been shown to be promising alternatives to platinum(II) drugs. However, their clinical success depends on achieving mechanisms of action that overcome Pt-resistance mechanisms. Electron-deficient organoruthenium complexes are an understudied class of compounds that exhibit unusual reactivity in solution and might offer novel anticancer mechanisms of action. Here, we evaluate the in vitro and in vivo anticancer properties of the electron-deficient organoruthenium complex [(p-cymene)Ru(maleonitriledithiolate)]. This compound is found to be highly cytotoxic: 5 to 60 times more potent than cisplatin towards ovarian (A2780 and A2780cisR), colon (HCT116 p53+/+ and HCT116 p53−/−), and non-small cell lung H460 cancer cell lines. It shows no cross-resistance and is equally cytotoxic to both A2780 and A2780cisR cell lines. Furthermore, unlike cisplatin, the remarkable in vitro antiproliferative activity of this compound appears to be p53-independent. In vivo evaluation in the hollow-fibre assay across a panel of cancer cell types and subcutaneous H460 non-small cell lung cancer xenograft model hints at the activity of the complex. Although the impressive in vitro data are not fully corroborated by the in vivo follow-up, this work is the first preclinical study of electron-deficient half-sandwich complexes and highlights their promise as anticancer drug candidates.     

Platinum(II) Complexes Bearing Triphenylphosphine and Chelating Oximes: Antiproliferative Effect and Biological Profile in Resistant Cells

Platinum(II) complexes of the type [Pt(Cl)(PPh₃){(κ²-N,O)-(1{C(R)=N(OH)-2(O)C₆H₄})}] with R=Me, H, ( 1 and 2 ) were synthesized and characterized. Single-crystal X-ray diffraction confirmed the proposed (SP4-3) configuration for 1 . Study of the antiproliferative activity, performed on a panel of human tumor cell lines and on mesothelial cells, highlighted complex 2 as the more effective. In particular, it showed a remarkable cytotoxicity in ovarian carcinoma cells (A2780) and interestingly, a significant antiproliferative effect on cisplatin resistant cells (A2780cis). Investigation into the intracellular mechanism of action demonstrated that 2 had a lower ability to platinate DNA than did cisplatin, which was taken as reference, and a notably higher uptake in resistant cells. A significant accumulation in mitochondria, along with the ability to induce concentration-dependent mitochondrial membrane depolarization and intracellular reactive oxygen species production, allowed us to propose a mitochondrion-mediated pathway as responsible for the interesting cytotoxic profile of complex 2 .     

Synthesis of Novel 2-Thiouracil-5-Sulfonamide Derivatives as Potent Inducers of Cell Cycle Arrest and CDK2A Inhibition Supported by Molecular Docking

In an effort to discover potent anticancer agents, 2-thiouracil-5-sulfonamides derivatives were designed and synthesized. The cytotoxic activity of all synthesized compounds was investigated against four human cancer cell lines viz A-2780 (ovarian), HT-29 (colon), MCF-7 (breast), and HepG2 (liver). Compounds 6b,d–g, and 7b showed promising anticancer activity and significant inhibition of CDK2A. Moreover, they were all safe when tested on WI38 normal cells with high selectivity index for cancer cells. Flow cytometric analysis for the most active compound 6e displayed induction of cell growth arrest at G1/S phase (A-2780 cells), S phase (HT-29 and MCF-7 cells), and G2/M phase (HepG2 cells) and stimulated the apoptotic death of all cancer cells. Moreover, 6e was able to cause cycle arrest indirectly through enhanced expression of cell cycle inhibitors p21 and p27. Finally, molecular docking of compound 6e endorsed its proper binding to CDK2A, which clarifies its potent anticancer activity.     

New Perfluorophtalate Complexes of Platinum(II) With Chemotherapeutic Potential

Two new platinum(II) complexes have been synthesized and their anti-tumour and anti-HIV activities have been evaluated.THE NEW COMPLEXES ARE: (i) cis-tetrafluorophthalate-ammine-morpholine-platinum(II) or MMF3 and (ii) cis-tetrafluorophthalate- ammine-piperidine-platinum(II) or MPF4. They were characterized by elemental analysis, IR spectra and (1)H and (13)C NMR spectra.They were tested against five human ovarian carcinoma cell lines, viz., CH1, CH1cisR, A2780, A2780cisR and SKOV-3. They were less active than cis-platin and showed cross-resistance with cis-platin in the CH1cisR and A2780cisR acquired resistance lines.They were also tested for possible anti-HIV activity using the HIV-I IIIB virus and C8166 cells, but they were inactive compared with AZT.     

Cellular Uptake, DNA Binding and Apoptosis Induction of Cytotoxic Trans-[PtCl(2)(N,N-dimethylamine)(Isopropylamine)] in A2780cisR Ovarian Tumor Cells

Trans-[PtCl(2)(N,N-dimethylamine)(isopropylamine)] is a novel trans-platinum compound that shows cytotoxic activity in several cisplatin resistant cell lines. The aim of this paper was to analyse, by means of molecular cell biology techniques and total reflection X-ray fluorescence (TXRF), the cytotoxic activity, the induction of apoptosis, the cellular uptake and the DNA binding of trans-[PtCl(2)(N,N-dimethylamine)(isopropylamine)] in the cisplatin resistant cell line A2780cisR. The results show that this drug is more cytotoxic and induces a higher amount of apoptotic cells than cisplatin in A2780cisR cells. However, the intracellular accumulation and extent of binding to DNA of trans-[PtCl(2)(N,N-dimethylamine)( isopropylamine)] is lower than that of cis-DDP. Moreover, trans-[PtCl(2)(N,N-dimethylamine)(isopropylaminae)] is partially inactivated by intracellular levels of glulathione. The result suggest that circumvention of ciplatin resistance by trans-[PtCl(2)(N,N-dimethylamine)(isopropylamine)] in A2780cisR cells might be related with the ability of this drug to induce apoptosis.     

FT-IR Microspectrometry Reveals the Variation of Membrane Polarizability due to Epigenomic Effect on Epithelial Ovarian Cancer

Ovarian cancer, as well as other cancers, is primarily caused by methylation at cytosines in CpG islands, but the current marker for ovarian cancer is low in sensitivity and failed in early-stage detection. Fourier transform infrared (FT-IR) spectroscopy is powerful in analysis of functional groups within molecules, and infrared microscopy illustrates the location of specific groups within single cells. In this study, we applied HPLC and FT-IR microspectrometry to study normal epithelial ovarian cell line immortalized ovarian surface epithelium (IOSE), two epithelial ovarian cell lines (A2780 and CP70) with distinct properties, and the effect of a cancer drug 5-aza-2''-deoxycytidine (5-aza) without labeling. Our results reveal that inhibition of methylation on cytosine with 5-aza initiates the protein expression. Furthermore, paraffin-adsorption kinetic study allows us to distinguish hypermethylated and hypomethyated cells, and this assay can be a potential diagnosis method for cancer screening.     

Synthesis and activity of a trinuclear platinum complex: [{trans-PtCl(NH3)2}2mu-{trans-Pt(3-hydroxypyridine)2(H2N(CH2)6NH2)2}]Cl4 in ovarian cancer cell lines

This paper describes the synthesis, characterisation, and cytotoxicity of a novel trinuclear platinum complex code named TH1. In addition to its activity against human ovarian cancer cell lines: A2780, A2780(cisR), and A2780(ZD0473R), cell uptake, DNA-binding, and the nature of the compound interaction with pBR322 plasmid DNA have been determined. TH1 is found to be significantly more cytotoxic than cisplatin - two times more active than cisplatin against the parent cell line A2780, thirteen times more active against the cisplatin-resistant cell line A2780(cisR) and 11.5 times more active against the cell line A2780(ZD0473R). Whereas the resistance factors for cisplatin as applied to the cell lines A2780 and A2780(cisR), and A2780 and A2780(ZD0473R) are 12.9 and 3.0 respectively, the corresponding values for TH1 are 1.98 and 0.5. The results suggest that TH1 has been able to significantly overcome resistance in A2780(cisR) and A2780(ZD0473R) cell lines. Whereas cisplatin binds with DNA forming mainly intrastrand GG adduct that causes local bending of a DNA strand, TH1 should bind with DNA forming mainly interstrand GG adducts that would cause more of a global change in DNA conformation. Provided it has favourable toxicity profile, TH1 has the potential to be developed into a highly active anticancer drug with a wider spectrum of activity than cisplatin.     

Anticancer Therapeutics That Target Selenoenzymes: Synthesis,Characterization, in vitro Cytotoxicity,and Thioredoxin Reductase Inhibition of a Series of Gold(I) Complexes Containing Hydrophilic Phosphine Ligands

Gold(I) complexes bearing water‐soluble phosphine ligands, including 1,3,5‐triaza‐7‐phosphaadamantane (PTA), 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane (DAPTA), and sodium triphenylphosphine trisulfonate (TPPTS), in combination with thionate ligands, were screened for their antiproliferative activities against human ovarian cancer cell lines A2780 either sensitive or resistant to cisplatin. In addition, the compounds were screened for their inhibition of mammalian thioredoxin reductases (TrxR), enzymes that are overexpressed in many tumor cells and contribute to drug resistance. The gold(I)–phosphine complexes efficiently inhibited cytosolic and mitochondrial TrxRs at concentrations that did not affect the related oxidoreductase glutathione reductase (GR). Additional complementary information on the enzyme metallation process and potential gold binding sites was obtained through the application of a specific biochemical assay using a thiol‐tagging reagent, BIAM (biotin‐conjugated iodoacetamide).     

Malignant Ascites Promote Adhesion of Ovarian Cancer Cells to Peritoneal Mesothelium and Fibroblasts

Although malignant ascites (MAs) are known to contribute to various aspects of ovarian cancer progression, knowledge regarding their role in the adhesion of cancer cells to normal peritoneal cells is incomplete. Here, we compared the effect of MAs and benign ascites (BAs) on the adhesion of A2780 and OVCAR-3 cancer cells to omentum-derived peritoneal mesothelial cells (PMCs) and peritoneal fibroblasts (PFBs). The results showed that MAs stimulated the adhesion of A2780 and OVCAR-3 cells to PMCs and PFBs more efficiently than did BAs, and the strongest binding occurred when both cancer and normal cells were exposed to the fluid. Intervention studies showed that MAs-driven adhesion of A2780 cells to PMCs/PFBs depends on the presence of TGF-β1 and HGF, whereas binding of OVCAR-3 cells was mediated by TGF-β1, GRO-1, and IGF-1. Moreover, MAs upregulated α5β1 integrin expression on PFBs but not on PMCs or cancer cells, vimentin expression in all cells tested, and ICAM-1 only in cancer cells. When integrin-linked kinase was neutralized in PMCs or PFBs, cancer cell adhesion to PMCs and PFBs decreased. Collectively, our report shows that MAs may contribute to the early stages of ovarian cancer metastasis by modulating the proadhesive interplay between normal and cancer cells.     

Synthesis, biological evaluation, and molecular modeling studies of rebeccamycin analogues modified in the carbohydrate moiety

A new series of indolocarbazole glycosides containing disaccharides were synthesized and their in vitro antiproliferative activity was evaluated against three human cancer cell lines (A2780, H460, and GLC4). Cytotoxicity appeared to be remarkably affected by the regio- and stereochemical features of the disaccharide moiety. In vivo antitumor activity of the compounds studied, two of which having IC(50)<100 nm, was determined using ovarian cancer cell line A2780 xenografted on nude mice. One compound showed an efficacy similar to that of the reference compound edotecarin, though with a lower long-lasting activity. The topoisomerase I inhibitory properties of some compounds were also examined. Molecular dynamics simulations of the ternary topoisomerase I-DNA-ligand complexes were performed to analyze the structural features of topoisomerase I poisoning with this class of indolocarbazoles. A plausible explanation of their biological behavior was provided. These theoretical results were compared with the recently published crystal structure of an indolocarbazole monosaccharide bound to the covalent human topoisomerase I-DNA complex.     

Organometallic ruthenium inhibitors of glutathione-S-transferase P1-1 as anticancer drugs

Ruthenium-arene complexes conjugated to ethacrynic acid were prepared as part of a strategy to develop novel glutathione-S-transferase (GST) inhibitors with alternate modes of activity through the organometallic fragment, ultimately to provide targeted ruthenium-based anticancer drugs. Enzyme kinetics and electrospray mass spectrometry experiments using GST P1-1 and its cysteine-modified mutant forms revealed that the complexes are effective enzyme inhibitors, but they also rapidly inactivate the enzyme by covalent binding at Cys 47 and, to a lesser extent, Cys 101. They are highly effective against the GST Pi-positive A2780 and A2780cisR ovarian carcinoma cell lines, are among the most effective ruthenium complexes reported so far, and target ubiquitous GST Pi overexpressed in many cancers.     

Apoptosis induction and DNA interstrand cross-link formation by cytotoxic trans-[PtCl2(NH(CH3)2)(NHCH(CH3)2) : cross-linking between d(G) and complementary d(C) within oligonucleotide duplexes

We have investigated the cytotoxic activity, the induction of apoptosis, and the interstrand cross-linking efficiency in the A2780cisR ovarian tumor cell line, after replacement of the two NH3 nonleaving groups in trans-[PtCl2(NH3)2] (trans-DDP) by dimethylamine and isopropylamine. The data show that trans-[PtCl2(NH(CH)2)(NHCH(CH3)2)] is able to circumvent resistance to cis-[PtCl2(NH3)2] (cis-DDP, cisplatin) in A2780cisR cells. In fact, trans-[PtCl2(NH(CH3)2)(NHCH(CH3)2)] shows a cytotoxic potency higher than that of cis-DDP and trans-DDP, with the mean IC50 values being 11, 58, and 300 microM, respectively. In addition, at equitoxic doses (concentrations of the platinum drugs equal to their IC50 values) and after 24 hours of drug treatment, the level of induction of apoptosis by trans-[PtCl2(NH(CH3)2)(NHCH(CH3)2)] is twice that produced by cis-DDP. Under the same experimental conditions, trans-DDP does not induce significant levels of apoptosis in A2780cisR cells. After 24 hours of incubation of A2780cisR cells at concentrations equal to the IC0o value of the platinum drugs, the level of DNA interstrand cross-links (ICLs) induced by trans-[PtCI2(NH(CH)2)(NHCH(CH3)] is two and three times higher, respectively, than those induced by cis-DDP and trans-DDP. We also found that trans-[PtCl2(NH(CH3)2)(NHCH(CH3)2)] formed DNA ICLs between guanine and complementary cytosine. We propose that, in A2780cisR cells, the induction of apoptosis by trans-[PtCl2(NH(CH3)2)(NHCH(CH3)2)] is related to its greater ability (relative to cis-DDP and trans-DDP) to form DNA ICLs.     

Trichodermin Induces G0/G1 Cell Cycle Arrest by Inhibiting c-Myc in Ovarian Cancer Cells and Tumor Xenograft-Bearing Mice

Ovarian cancer is a fatal gynecological cancer because of a lack of early diagnosis, which often relapses as chemoresistant. Trichodermin, a trichothecene first isolated from Trichoderma viride, is an inhibitor of eukaryotic protein synthesis. However, whether trichodermin is able to suppress ovarian cancer or not was unclear. In this study, trichodermin (0.5 µM or greater) significantly decreased the proliferation of two ovarian cancer cell lines A2780/CP70 and OVCAR-3. Normal ovarian IOSE 346 cells were much less susceptible to trichodermin than the cancer cell lines. Trichodermin predominantly inhibited ovarian cancer cells by inducing G0/G1 cell cycle arrest rather than apoptosis. Trichodermin decreased the expression of cyclin D1, CDK4, CDK2, retinoblastoma protein, Cdc25A, and c-Myc but showed little effect on the expression of p21^Waf1/Cip1, p27^Kip1, or p16^Ink4a. c-Myc was a key target of trichodermin. Trichodermin regulated the expression of Cdc25A and its downstream proteins via c-Myc. Overexpression of c-Myc attenuated trichodermin’s anti-ovarian cancer activity. In addition, trichodermin decelerated tumor growth in BALB/c nude mice, proving its effectiveness in vivo. These findings suggested that trichodermin has the potential to contribute to the treatment of ovarian cancer.     

Cationic and Neutral N‐Heterocyclic Carbene Gold(I) Complexes: Cytotoxicity,NCI‐60 Screening,Cellular Uptake,Inhibition of Mammalian Thioredoxin Reductase,and Reactive Oxygen Species Formation

A structurally diverse library of 14 gold(I) cationic bis(NHC) and neutral mono(NHC) complexes (NHC: N‐heterocyclic carbene) was synthesized and characterized in this work. Four of them were new cationic gold(I) complexes containing functionalized NHCs, and their X‐ray crystal structures are presented herein. All of the complexes were investigated for their anticancer activities in four cancer cell lines, including a cisplatin‐resistant variant, and a noncancerous cell line. Seven of the cationic gold(I) complexes were found to display high and specific cytotoxic activities toward cancer cells. Two of them were even able to overcome cisplatin resistance. Two highly potent cationic complexes ( 11 and 15 ) were also submitted to the NCI‐60 cancer panel for further cytotoxicity evaluation. Complex 15 showed a surprisingly high potency toward leukemia among the nine examined cancer subtypes, particularly toward the CCRF‐CEM leukemia cell line with a concentration for 50 % inhibition of growth down to 79.4 nm . In addition, cationic complex 13 , which demonstrated a remarkable cytotoxicity against hepatocellular carcinoma, was selected to obtain insight into the mechanistic aspects in HepG2 cells. Cellular uptake measurements were indicative of good bioavailability. By various biochemical assays, this complex was found to effectively inhibit thioredoxin reductase and its cytotoxicity toward HepG2 cells was found to be reactive oxygen species dependent.     

Highly Cytotoxic Osmium(II) Compounds and Their Ruthenium(II) Analogues Targeting Ovarian Carcinoma Cell Lines and Evading Cisplatin Resistance Mechanisms

(1) Background: Ruthenium and osmium complexes attract increasing interest as next generation anticancer drugs. Focusing on structure-activity-relationships of this class of compounds, we report on 17 different ruthenium(II) complexes and four promising osmium(II) analogues with cinnamic acid derivatives as O,S bidentate ligands. The aim of this study was to determine the anticancer activity and the ability to evade platin resistance mechanisms for these compounds. (2) Methods: Structural characterizations and stability determinations have been carried out with standard techniques, including NMR spectroscopy and X-ray crystallography. All complexes and single ligands have been tested for cytotoxic activity on two ovarian cancer cell lines (A2780, SKOV3) and their cisplatin-resistant isogenic cell cultures, a lung carcinoma cell line (A549) as well as selected compounds on three non-cancerous cell cultures in vitro. FACS analyses and histone γH2AX staining were carried out for cell cycle distribution and cell death or DNA damage analyses, respectively. (3) Results: IC50 values show promising results, specifically a high cancer selective cytotoxicity and evasion of resistance mechanisms for Ru(II) and Os(II) compounds. Histone γH2AX foci and FACS experiments validated the high cytotoxicity but revealed diminished DNA damage-inducing activity and an absence of cell cycle disturbance thus pointing to another mode of action. (4) Conclusion: Ru(II) and Os(II) compounds with O,S-bidentate ligands show high cytotoxicity without strong effects on DNA damage and cell cycle, and this seems to be the basis to circumvent resistance mechanisms and for the high cancer cell specificity.     

Platinum(II) phenanthroimidazoles for targeting telomeric G-quadruplexes

A rationally designed progression of phenanthroimidazole platinum(II) complexes were examined for their ability to target telomere-derived intramolecular G-quadruplex DNA. Through the use of circular dichroism, fluorescence displacement assays, and molecular modeling we show that these complexes template and stabilize G-quadruplexes from sequences based on the human telomeric repeat (TTAGGG)(n). The greatest stabilization was observed for the p-chlorophenyl derivative 6((G4)DC(50) =0.31 μM). We also show that the G-quadruplex binding complexes are able to inhibit telomerase activity through a modified telomerase repeat amplification protocol (TRAP-LIG assay). Preliminary cell studies show that complex 6 is preferentially cytotoxic toward cancer over normal cell lines, indicating its potential use in cancer therapy.