👤 Dirsch VM

Efforts to identify anti-cancer therapeutics and understand tumor-immune interactions are built with in vitro models that do not match the microenvironmental characteristics of human tissues. Using in vitro models which mimic the physical properties of healthy or cancerous tissues and a physiologically relevant culture medium, we demonstrate that the chemical and physical properties of the microenvironment regulate the composition and topology of the glycocalyx. Remarkably, we find that cancer and age-related changes in the physical properties of the microenvironment are sufficient to adjust immune surveillance via the topology of the glycocalyx, a previously unknown phenomenon observable only with a physiologically relevant culture medium. Show less

Title: New ruthenium(II) complexes with cyclic thio- and semicarbazone: evaluation of cytotoxicity and effects on cell migration and apoptosis of lung cancer cells. Abstract: We describe the synthesis, physicochemical characterization, and in vitro antitumor assays of four novel analogous ruthenium(II) complexes with general formula cis-[RuII(N-L)(P-P)2]PF6, where P-P = bis(diphenylphosphine)methane (dppm, in complexes 1 and 2) or bis(diphenylphosphine)ethane (dppe, in complexes 3 and 4) and N-L = 5,6-diphenyl-4,5-dihydro-2H-[1,2,4]triazine-3-thione (Btsc, in complexes 1 and 3) or 5,6-diphenyltriazine-3-one (Bsc, in complexes 2 and 4). The data were consistent with cis arrangement of the biphosphine ligands. For the Btsc and Bsc ligands, the data pointed to monoanionic bidentate coordination to ruthenium(II) through N,S and N,O, respectively. Single-crystal X-ray diffraction showed that complex 1 crystallized in the monoclinic system, space group P21/c. Determination of the cytotoxicity profiles of complexes 1-4 gave SI values ranging from 1.19 to 3.50 against the human lung adenocarcinoma cell line A549 and the non-tumor lung cell line MRC-5. Although the molecular docking studies suggested that the interaction between DNA and complex 4 was energetically favorable, the experimental results showed that they interacted weakly. Overall, our results demonstrated that these novel ruthenium(II) complexes have interesting in vitro antitumor potential and this study may contribute to further studies in medicinal inorganic chemistry. Show less

For some cancer subtypes, such as triple-negative breast cancer, there are no specific therapies, which leads to a poor prognosis associated with invasion and metastases. Ruthenium complexes have been developed to act in all steps of tumor growth and its progression. In this study, we investigated the effects of Ruthenium (II) complexes coupled to the amino acids methionine (RuMet) and tryptophan (RuTrp) on the induction of cell death, clonogenic survival ability, inhibition of angiogenesis, and migration of MDA-MB-231 cells (human triple-negative breast cancer). The study also demonstrated that the RuMet and RuTrp complexes induce cell cycle blockage and apoptosis of MDA-MB-231 cells, as evidenced by an increase in the number of Annexin V-positive cells, p53 phosphorylation, caspase 3 activation, and poly(ADP-ribose) polymerase cleavage. Moreover, morphological changes and loss of mitochondrial membrane potential were detected. The RuMet and RuTrp complexes induced DNA damage probably due to reactive oxygen species production related to mitochondrial membrane depolarization. Therefore, the RuMet and RuTrp complexes acted directly on breast tumor cells, leading to cell death and inhibiting their metastatic potential; this reveals the potential therapeutic action of these drugs. Show less

Ruthenium(II) complexes (Ru1-Ru5), with the general formula [Ru(N-S)(dppe)₂]PF₆, bearing two 1,2-bis(diphenylphosphino)ethane (dppe) ligands and a series of mercapto ligands (N-S), have been developed. The combination of these ligands in the complexes endowed hydrophobic species with high cytotoxic activity against five cancer cell lines. For the A549 (lung) and MDA-MB-231 (breast) cancer cell lines, the IC₅₀ values of the complexes were 288- to 14-fold lower when compared to cisplatin. Furthermore, the complexes were selective for the A549 and MDA-MB-231 cancer cell lines compared to the MRC-5 nontumor cell line. The multitarget character of the complexes was investigated by using calf thymus DNA (CT DNA), human serum albumin, and human topoisomerase IB (hTopIB). The complexes potently inhibited hTopIB. In particular, complex [Ru(dmp)(dppe)₂]PF₆ (Ru3), bearing the 4,6-diamino-2-mercaptopyrimidine (dmp) ligand, effectively inhibited hTopIB by acting on both the cleavage and religation steps of the catalytic cycle of this enzyme. Molecular docking showed that the Ru1-Ru5 complexes have binding affinity by active sites on the hTopI and hTopI-DNA, mainly via π-alkyl and alkyl hydrophobic interactions, as well as through hydrogen bonds. Complex Ru3 displayed significant antitumor activity against murine melanoma in mouse xenograph models, but this complex did not damage DNA, as revealed by Ames and micronucleus tests. Show less

Ruthenium complexes have been extensively explored as potential molecules for cancer treatment. Considering our previous findings on the remarkable cytotoxic activity exhibited by the ruthenium (II) complex 3-hydroxy-4-methoxybenzoate (hmxbato)-cis-[Ru^II(ŋ²-O₂CC₇H₇O₂)(dppm)₂]PF₆ against Leishmania promastigotes and also the similar metabolic characteristics between trypanosomatids and tumor cells, the present study aimed to analyze the anticancer potential of hmxbato against lung tumor cells, as well as the partial death mechanisms involved. Hmxbato demonstrated selective cytotoxicity against A549 lung tumor cells. In addition, this complex at a concentration of 3.8 µM was able to expressively increase the generation of reactive oxygen species (ROS) in tumor cells, causing an oxidative stress that may culminate in: (1) reduction in cellular proliferation; (2) changes in cell morphology and organization patterns of the actin cytoskeleton; (3) cell arrest in the G2/M phase of the cell cycle; (4) apoptosis; (5) changes in the mitochondrial membrane potential and (6) initial DNA damage. Furthermore, we demonstrated that the induction of programmed cell death can occur by the intrinsic apoptotic pathway through the activation of caspases. It is also worth highlighting that hmxbato exhibited predominant actions on A549 tumor cells in comparison to BEAS-2B normal bronchial epithelium cells, which makes this complex an interesting candidate for the design of new drugs against lung cancer. Show less

Six new ruthenium(ii) complexes with lapachol (Lap) and lawsone (Law) with the general formula [Ru(L)(P-P)(bipy)]PF6, where L = Lap or Law, P-P = 1,2'-bis(diphenylphosphino)ethane (dppe), 1,4'-bis(diphenylphosphino)butane (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppf) and bipy = 2,2'-bipyridine, were synthesized, fully characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis, IR spectroscopies and three of them by X-ray crystallography. All six complexes were active against breast (MCF-7 and MDA-MB-231) and prostate (DU-145) cancer cell lines with lower IC50 values than cisplatin. Complex [Ru(Lap)(dppe)(bipy)]PF6 (1a) showed significant selectivity for MDA-MB-231, a model of triple-negative breast cancer (TNBC), as compared to the "normal-like" human breast epithelial cell line, MCF-10A. Complex (1a) inhibited TNBC colony formation and induced loss of cellular adhesion. Furthermore, the complex (1a) induced mitochondrial dysfunction and generation of ROS, as is involved in the apoptotic cell death pathway. Preferential cellular uptake of complex (1a) was observed in MDA-MB-231 cells compared to MCF-10A cells, consistent with the observed selectivity for tumorigenic vs. non-tumorigenic cells. Taken together, these results indicate that ruthenium complexes containing lapachol and lawsone as ligands are promising candidates as chemotherapeutic agents. Show less

Herein we discuss five ruthenium(ii) complexes with good cytotoxicity against cancer cells. These complexes are named [Ru(tzdt)(bipy)(dppb)]PF6 (1), [Ru(mmi)(bipy)(dppb)]PF6 (2), [Ru(dmp)(bipy)(dppb)]PF6 (3), [Ru(mpca)(bipy)(dppb)]PF6 (4) and [Ru(2mq)(bipy)(dppb)]PF6 (5), where tzdt = 1,3-thiazolidine-2-thione, mmi = mercapto-1-methyl-imidazole, dmp = 4,6-diamino-2-mercaptopyrimidine, mpca = 6-mercaptopyridine-3-carboxylic acid, 2mq = 2-mercapto-4(3H)-quinazolinone, bipy = 2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. In vitro cell culture experiments revealed significant cytotoxic activity for 1-5 against MDA-MB-231, MCF-7, A549, DU-145 and HepG2 tumor cells, higher than that for the standard anticancer drug cisplatin. Compound/DNA interaction studies were carried out showing that 1-5 interact with DNA by electrostatic force of attraction or by hydrogen bonding. Moreover, the complexes interact, moderately and spontaneously, with human serum albumin (HSA) through the hydrophobic region. The five complexes are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (TopIB), and complex 1 is found to be the most efficient TopIB inhibitor among the five compounds. The inhibitory effect and analysis of different steps of the TopIB catalytic cycle indicate that complex 1 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and has no effect on the religation step. Complexes 1, 2 and 3 did not show mutagenic activity when they were evaluated by the cytokinesis-block micronucleus cytome assay in HepG2 cells and the Ames test in the presence and absence of mouse liver S9 metabolic activation. Therefore, it is necessary to perform further in-depth analysis of the therapeutic potential of these promising ruthenium complexes as anticancer drugs. Show less

In this paper, four new ruthenium complexes, [Ru(N-S)(dppm)2]PF6 (1), [Ru(N-S)(dppe)2]PF6 (2), [Ru(N-S)2(dppp)] (3) and [Ru(N-S)2(PPh3)2] (4) [dppm = 1,1-bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, PPh3 = triphenylphosphine and N-S = 2-mercaptopyrimidine anion] were synthesized and characterized using spectroscopy techniques, molar conductance, elemental analysis, electrochemical techniques and X-ray diffraction. The DNA binding studies were investigated using voltammetry and spectroscopy techniques. The results show that all complexes exhibit a weak interaction with DNA. HSA interaction with the complexes was studied using fluorescence emission spectroscopy, where the results indicate a spontaneous interaction between the species by a static quenching mechanism. The cytotoxicity of the complexes was evaluated against A549, MDA-MB-231 and HaCat cells by MTT assay. Complexes (1) and (2), which are very active against triple negative MDA-MB-231, were subjected to further biological tests with this cell line. The cytotoxic activity triggered by the complexes was confirmed by clonogenic assay. Cell cycle analyses demonstrated marked anti-proliferative effects, especially at the G0/G1 and S phases. The morphological detection of apoptosis and necrosis - HO/PI and Annexin V-FITC/PI assay, elucidated that the type of cell death triggered by these complexes was probably by apoptosis. The in vivo toxicological assessment performed on zebrafish embryos revealed that complexes (1) and (2) did not present embryotoxic or toxic effects during embryonic and larval development showing that they are promising new prototypes of safer and more effective drugs for triple negative breast cancer treatment. Show less

New Ru(II) complexes with lawsone (law) characterized as trans-[Ru(law)(PPh₃)₂(N-N)]PF₆, where PPh₃ means triphenylphosphine and N-N is 2,2'-bipyridine (1), 4,4'-dimethyl-2,2'-bipyridine (2), 4,4'-dimethoxy-2,2'-bipyridine (3), 1,10-phenanthroline (4) or 4,7-diphenyl-1,10-phenanthroline (5), induce apoptosis in tumor cells. Cytotoxicity of the complexes against the tumor cell lines DU-145 (prostate cancer cells), MCF-7 (breast cancer cells), A549 (lung cancer cells) and lung non-tumor cell line MRC-5 demonstrated promising IC₅₀ values, lower than those found for the cisplatin, a drug used as a reference. Due to the high cytotoxic activity and selectivity against A549 cells line, complex (5) was selected for detailed assays. The complex (5) inhibits cells migration in concentrations in a nanomolar range, inducing tumor cell death by apoptosis, as confirmed by flow cytometry experiments. Furthermore, the antiproliferative activity of complex (5) on A549 tumor cells is attributed to a cell cycle arrest at the Sub G1 phase, followed by a decrease in the number of cells at the S phase. In addition, the interaction of the complexes (1-5) with CT-DNA was evaluated by circular dichroism, in which no changes in the secondary structure of DNA were observed, suggesting a weak interaction of the complexes with the biomolecule. On the other hand, complexes (1-5) showed a higher interaction with human serum albumin (HSA) by non-covalent van der Waals forces and hydrogen bonding, resulting in static quenching. Show less

Herein we synthesized two new ruthenium(II) compounds [Ru(pySH)(bipy)(dppb)]PF6 (1) and [Ru(HSpym)(bipy)(dppb)]PF6 (2) that are analogs to an antitumor agent recently described, [Ru(SpymMe2)(bipy)(dppb)]PF6 (3), where [(Spy) = 2-mercaptopyridine anion; (Spym) = 2-mercaptopyrimidine anion and (SpymMe2) = 4,6-dimethyl-2-mercaptopyrimidine anion]. In vitro cell culture experiments revealed significant anti-proliferative activity for 1-3 against HepG2 and MDA-MB-231 tumor cells, higher than the standard anti-cancer drugs doxorubicin and cisplatin. No mutagenicity is detected when compounds are evaluated by cytokinesis-blocked micronucleus cytome and Ames test in the presence and absence of S9 metabolic activation from rat liver. Interaction studies show that compounds 1-3 can bind to DNA through electrostatic interactions and to albumin through hydrophobic interactions. The three compounds are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (Top1). Compound 3 is the most efficient Top1 inhibitor and the inhibitory effect is enhanced upon pre-incubation with the enzyme. Analysis of different steps of Top1 catalytic cycle indicates that 3 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and slows down the religation reaction. Molecular docking shows that 3 preferentially binds closer to the residues of the active site when Top1 is free and lies on the DNA groove downstream of the cleavage site in the Top1-DNA complex. Thus, 3 can be considered in further studies for a possible use as an anticancer agent. Show less

The synthesis and spectroscopic characterization of nine π-arene piano-stool ruthenium (II) complexes with aromatic dinitrogen chelating ligands or containing chloroquine (CQ), are described in this study: [Ru(η(6)-C10H14)(phen)Cl]PF6 (1), [Ru(η(6)-C10H14)(dphphen)Cl]PF6 (2), [Ru(η(6)-C10H14)(bipy)Cl]PF6 (3), [Ru(η(6)-C10H14)(dmebipy)Cl]PF6 (4) and [Ru(η(6)-C10H14)(bdutbipy)Cl]PF6 (5), [Ru(η(6)-C10H14)(phen)CQ](PF6)2 (6), [Ru(η(6)-C10H14)(dphphen)CQ](PF6)2 (7), [Ru(η(6)-C10H14)(bipy)CQ](PF6)2 (8), [Ru(η(6)-C10H14)(dmebipy)CQ](PF6)2 (9): [1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (dphphen), 2,2'-bipyridine (bipy), 5,5'-dimethyl-2,2'-bipyridine (dmebipy), and 4,4'-di-t-butyl-2,2'-bipyridine (dbutbipy)]. The solid state structures of five ruthenium complexes (1-5) were determined by X-ray crystallography. Electrochemical experiments were performed by cyclic voltammetry to estimate the redox potential of the Ru(II)/Ru(III) couple in each case. Their interactions with DNA and BSA, and activity against four cell lines (L929, A549, MDA-MB-231 and MCF-7) were evaluated. Compounds 2, 6 through 9, interact with DNA which was comparable to the one observed for free chloroquine. The results of fluorescence titration revealed that these complexes strongly quenched the intrinsic fluorescence of BSA following a static quenching procedure. Binding constants (Kb) and the number of binding sites (n~1) were calculated using modified Stern-Volmer equations. The thermodynamic parameters ΔG at different temperatures were calculated and subsequently the values of ΔH and ΔS were also calculated, which revealed that hydrophobic and electrostatic interactions play a major role in the BSA-complex association. The MTT assay results indicated that complexes 2, 5 and 7 showed cytostatic effects at appreciably lower concentrations than those needed for cisplatin, chloroquine and doxorubicin. Show less

Activation of the transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2) is one of the major cellular defense lines against oxidative and xenobiotic stress, but also influences genes involved in lipid and glucose metabolism. It is unresolved whether the cytoprotective and metabolic responses mediated by Nrf2 are connected or separable events in non-malignant cells. In this study we show that activation of Nrf2, either by the small molecule sulforaphane or knockout of the Nrf2 inhibitor Keap1, leads to increased cellular glucose uptake and increased glucose addiction in fibroblasts. Upon Nrf2 activation glucose is preferentially metabolized through the pentose phosphate pathway with increased production of NADPH. Interference with the supply of glucose or the pentose phosphate pathway and NADPH generation not only hampers Nrf2-mediated detoxification of reactive oxygen species on the enzyme level but also Nrf2-initiated expression of antioxidant defense proteins, such as glutathione reductase and heme-oxygenase1. We conclude that the Nrf2-dependent protection against oxidative stress relies on an intact pentose phosphate pathway and that there is crosstalk between metabolism and detoxification already at the level of gene expression in mammalian cells. Show less

The reaction of cis-[RuCl(2)(dppb)(N-N)], dppb=1,4-bis(diphenylphosphino)butane, complexes with the ligand HSpymMe(2), 4,6-dimethyl-2-mercaptopyrimidine, yielded the cationic complexes [Ru(SpymMe(2))(dppb)(N-N)]PF(6), N-N=bipy (1) and Me-bipy (2), bipy=2,2'-bipyridine and Me-bipy=4,4'-dimethyl-2,2'-bipyridine, which were characterized by spectroscopic and electrochemical techniques and X-ray crystallography and elemental analysis. Additionally, preliminary in vitro tests for antimycobacterial activity against Mycobacterium tuberculosis H37Rv ATCC 27264 and antitumor activity against the MDA-MB-231 human breast tumor cell line were carried out on the new complexes and also on the precursors cis-[RuCl(2)(dppb)(N-N)], N-N=bipy (3) and Me-bipy (4) and the free ligands dppb, bipy, Me-bipy and SpymMe(2). The minimal inhibitory concentration (MIC) of compounds needed to kill 90% of mycobacterial cells and the IC(50) values for the antitumor activity were determined. Compounds 1-4 exhibited good in vitro activity against M. tuberculosis, with MIC values ranging between 0.78 and 6.25microg/mL, compared to the free ligands (MIC of 25 to >50microg/mL) and the drugs used to treat tuberculosis. Complexes 1 and 2 also showed promising antitumor activity, with IC(50) values of 0.46+/-0.02 and 0.43+/-0.08microM, respectively, against MDA-MB-231 breast tumor cells. Show less