👤 Zou Q

We have recently demonstrated that complexation with (η(6)-arene)Ru(II) fragments confers 4-anilinoquinazoline pharmacophores a higher potential for inducing cellular apoptosis while preserving the highly inhibitory activity of 4-anilinoquinazolines against EGFR and the reactivity of the ruthenium centre to 9-ethylguanine (Chem. Commun., 2013, 49, 10224-10226). Reported herein are the synthesis, characterisation and evaluation of the biological activity of a new series of ruthenium(ii) complexes of the type [(η(6)-arene)Ru(N,N-L)Cl]PF6 (arene = p-cymene, benzene, 2-phenylethanol or indane, L = 4-anilinoquinazolines). These organometallic ruthenium complexes undergo fast hydrolysis in aqueous solution. Intriguingly, the ligation of (arene)Ru(II) fragments with 4-anilinoquinazolines not only makes the target complexes excellent EGFR inhibitors, but also confers the complexes high affinity to bind to DNA minor grooves while maintaining their reactivity towards DNA bases, characterising them with dual-targeting properties. Molecular modelling studies reveal that the hydrolysis of these complexes is a favourable process which increases the affinity of the target complexes to bind to EGFR and DNA. In vitro biological activity assays show that most of this group of ruthenium complexes are selectively active inhibiting the EGF-stimulated growth of the HeLa cervical cancer cell line, and the most active complex [(η(6)-arene)Ru(N,N-L13)Cl]PF6 (, IC50 = 1.36 μM, = 4-(3'-chloro-4'-fluoroanilino)-6-(2-(2-aminoethyl)aminoethoxy)-7-methoxyquinazoline) is 29-fold more active than its analogue, [(η(6)-arene)Ru(N,N-ethylenediamine)Cl]PF6, and 21-fold more active than gefitinib, a well-known EGFR inhibitor in use clinically. These results highlight the strong promise to develop highly active ruthenium anticancer complexes by ligation of cytotoxic ruthenium pharmacophores with bioactive organic molecules. Show less

A series of six Ru(arene) complexes, [(η(6)-p-cymene)Ru(dpb)(py-R)](2+) (1-6, dpb = 2,3-bis(2-pyridyl)benzoquinoxaline, py-R = 4-substituted pyridine, R = N(CH3)2, NH2, OCH3, H, COOCH3 and NO2), were synthesized and their photochemical and photobiological properties were compared in detail. The electron push/pull character of the R groups has a significant impact on both ligand photodissociation and (1)O2 generation of the complexes. The photoinduced DNA covalent binding capabilities increase from 1 to 6 under both aerobic and anaerobic conditions, and DNA photocleavage occurs simultaneously in aerobic environments. 4 has the most potent phototoxicity against human lung carcinoma A549 cells among the examined complexes. The substituent effect may be ascribed to the influences of the R groups on the energy levels of (3)MC and (3)MLCT states as well as the energy gaps between (3)MC, (3)MLCT and dpb-based (3)IL states. Similar chemical modification on bidentate and arene ligands or other sites of the pyridine ligand may lead to more efficient agents with PDT and/or PACT activities. Show less

Ruthenium based complexes are promising antitumour candidates due to their lower toxicity and better water-solubility compared to the platinum antitumour complexes. An epidermal growth factor receptor (EGFR) has been found to be overexpressed in a large set of tumour cells. In this work, a series of organoruthenium complexes containing EGFR-inhibiting 4-anilinoquinazoline pharmacophores were synthesised and characterised. These complexes exhibited excellent inhibitory activity against EGFR and high affinity to interact with DNA via minor groove binding, featuring dual-targeting properties. In vitro screening demonstrated that the as-prepared ruthenium complexes are anti-proliferating towards a series of cancer cell lines, in particular the non-small-cell lung cancer cell line A549. Fluorescence-activated cell sorting analysis and fluorescence microscopy revealed that the most active complex 3 induced much more early-stage cell apoptosis than its cytotoxic arene ruthenium analogue and the EGFR-inhibiting 4-anilinoquinazolines, verifying the synergetic effect of the two mono-functional pharmacophores. Show less

The ruthenium DMSO complexes cis-Ru(II)C12(DMSO)4 and [(DMSO)2H][trans-Ru(III)Cl4(DMSO)2] reacted with 4-(3'-chloro-4'-fluoroanilino)-6-(2-(2-aminoethyl)aminoethoxy)-7-methoxyquinazoline (L1), 4-(3'-chloro-4'-fluoroanilino)-6-(2-(1H-imidazol-1-yl)ethoxy)-7-methoxy quinazoline (L2), N-(benzo[d]imidazol-4-yl)-6,7-dimethoxyquinazolin-4-amine hydrochloride (L3), 5-(6,7-dimethoxyquinazolin-4-ylamino)quinolin-8-ol hydrochloride (L4), respectively, to afford [Ru(II)Cl2(DMSO)2(L1)] (1), [Ru(III)Cl3(DMSO)(L1)] (2), [Ru(III)Cl4(DMSO)(H-L2)] (3), [Ru(III)Cl4(DMSO)(H-L3)] (4), and [Ru(III)Cl3(DMSO)(H-L4)] (5), which were characterised by mass spectrometry, NMR, elementary analysis and single crystal X-ray diffraction (complex 1). Experimental screening (ELISA) showed that complexes 1, 2 and 3 are remarkably inhibitory towards epidermal growth factor receptor (EGFR) with IC50 values at submicromolar or nanomolar level. Docking studies indicated that complexation with ruthenium has little interference with the formation of the two essential H-bonds between the N3 of the quinazoline ring in L1 and L2 and O-H of Thr766 through a water molecule, and the N1 of the quinazoline ring and N-H of Met769 in EGFR. Moreover, complex 2 was shown to be more active against the EGF-stimulated proliferation of human breast cancer cell line MCF-7 than the better EGFR inhibitor 4-(3'-chloro-4'-fluoroanilino)-6,7-dimethoxyquinazoline, being more potential to induce early-stage apoptosis than gefitinib. These imply that apart from inhibiting EGFR, complex 2 may involve in regulating other biological events related to the proliferation of MCF-7, implicating a novel type of multi-targeting metal-based anticancer agents. Show less

Transition metal complexes with dual functions of DNA photobinding via coordination and DNA photocleavage via(1)O2 may present potent antitumor activities with high selectivity and a wide anticancer spectrum. We herein report such a complex, [(η(6)-p-cymene)Ru(dpb)(py)](2+) (dpb = 2,3-bis(2-pyridyl)benzoquinoxaline, py = pyridine, 1). The highly delocalized nature of dpb provides 1 with long wavelength-absorbing properties and a long-lived excited state, facilitating (1)O2 generation. Additionally, the bulky nature of dpb leads to a distorted coordination geometry, and allow the (3)MC (metal-centered) state to be more accessible. From this, dissociation of py and dpb may occur, followed by the coordination of the resultant Ru fragment to nucleic bases if DNA is present. The dissociation of dpb can turn on fluorescence of its own, enabling real-time imaging of the photoactivation process. The fascinating properties of 1 and the underlying mechanisms that occur may provide guidelines for developing more efficient metallodrugs with dual potential for photodynamic therapy (PDT) and photoactivated chemotherapy (PACT). Show less

In this paper, drug-like properties of two series of carbonyl metal CO-releasing molecules, Ru(CO)₃Cl(n)L (n=1, L=amino acid or its derivatives 1-7, L=acetylacetone 8 or 2,2'-bipyridyl 9; n=2, L=aminopyridine derivatives 10-13; n=0, L=salicylaldehyde Schiff base 14-15) and M(CO)₅L(M=Cr, Mo, W; L=glycine methyl ester 16-18; L=N-methyl imidazole 19-21), were preliminarily evaluated from four aspects involving in cytotoxicity, in vivo toxicity, bio-distribution and metabolism. Cytotoxic effects of all complexes were assayed by MTT. IC₅₀ values of complexes 1-15 were 39.55-240.16mg/l, and those of complexes 16 and 18 were 21.36-22.21 mg/l. Toxicity tests of mice used oral acute toxic class method and got LD₅₀ values of some complexes; among them, LD₅₀ of complex 1 was in 800-1000 mg/kg, complex 7 in 1100-1500 mg/kg and complex 18 in 75-125 mg/kg. After several consecutive administrations, tested complexes severely damaged liver and kidney in both functional and morphological aspects. And by metal ions measurements using ICP-AES, we found that the tested complexes were unevenly distributed in tissues and organs. In vivo, Ru(II) in complexes was oxidized to Ru(III) by P450 enzymes, and for Mo(0) and W(0) in complexes, part of them transformed into higher oxidation state, the others kept original state. Show less

Two ruthenium(II) complexes, [Ru(L)2(p-tFMPIP)](ClO4)2 (L = bpy, 1; phen, 2; p-tFMPIP = 2-(4-(trifluoromethyphenyl)-1H-imidazo[4,5f][1,10] phenanthroline)), were prepared by microwave-assisted synthesis technology. The inhibitory activity evaluated by MTT assay shown that 2 can inhibit the growth of MDA-MB-231 cells with inhibitory activity (IC50) of 16.3 μM, which was related to the induction of apoptosis. Besides, 2 exhibit low toxicity against normal HAcat cells. The inhibitory growth activity of both complexes related to the induction of apoptosis was also confirmed. Furthermore, the studies on the interaction of both complexes with c-myc G4 DNA shown that 1 and 2 can stabilize the conformation of c-myc G4 DNA in groove binding mode, which has been rational explained by using DFT theoretical calculation methods. In a word, this type of ruthenium(II) complexes can act as potential apoptosis inducers with low toxicity in clinic by stabilizing c-myc G4 DNA. Show less

Effective chemotherapy drugs for cancer that would inhibit tumor growth and suppress metastasis are currently lacking. In this study, a series of arene ruthenium complexes, [(η6-arene)Ru(H2iip)Cl]Cl (arene = p-cymene, RAWQ03; CH3C6H5, RAWQ04; and C6H6, RAWQ11), were synthesized and their inhibitory activity against tumor cells were evaluated. The results showed that the complex RAWQ11 inhibited the growth of MDA-MB-231 breast cancer cells by inducing S-phase arrest, which is closely related to the inhibition of cell mitosis-mediated cell nucleus damage. Further studies showed that RAWQ11 can inhibit the invasion and metastasis of MDA-MB-231 cells. The morphology of MDA-MB-231 cells changed, the number of focal adhesions decreased, and the stress fibers de-polymerized upon dealing with the complex RAWQ11. The FITC-gelatin assay confirmed that the formation of invadopodia in MDA-MB-231 cells was significantly blocked by RAWQ11. Furthermore, RAWQ11 can block the AKT signal pathway by upregulating the PTEN expression through binding and downregulating miR-21. These results demonstrated that this type of arene ruthenium(ii) complex can block the invadopodia formation by regulating the PTEN/AKT signal pathway mediated by miR-21 to inhibit the invasion and metastasis of breast cancer cells. Therefore, this complex can be used as a potential dual functional agent to inhibit the growth and metastasis of tumor cells. Show less

Studies have shown that ruthenium complexes have relatively strong anticancer activity, cell uptake of drugs have a crucial impact on the pharmacological activity, using autofluorescence of ruthenium complexes could effectively track cancer cells and drug distribution, transport accurately in real time. In this work, we present the synthesis and detailed characterization of two novel Ru(II) complexes with hydrophobic ancillary ligands, namely [Ru(bpy)2(5-idip)](2+) (RBD) and [Ru(phen)2(5-idip)](2+) (RPD) (5-idip = 2-indole-[4,5-f][1,10]phenanthroline). We have shown that RPD can enter the HeLa cells efficiently through non-endocytotic, but energy-dependent mechanism and first accumulated in lysosomes, and then escape from the lysosomes and localize within the nuclei, efficiently lead to the inhibition of DNA transcription and translation and induced cell apoptosis. Further studies on the mechanism of apoptosis in HeLa cells demonstrate that RPD is able to induce mitochondria-mediated apoptosis in HeLa cells through activation of initiator caspase-9 and down-stream effector caspase-3 and -7 and cleavage of PARP. We have also demonstrated that RPD bind to telomeric G-quadruplex DNA effectively and selectively, together with increased p21 and p16 expression. Our findings suggest that RPD induces HeLa cell apoptosis through mitochondria-mediated pathway and inhibition of telomerase activity. RPD may be a candidate for further evaluation as a chemotherapeutic agent for human cancers. Show less

Ruthenium (Ru) polypyridyl complexes have emerged as leading players among the potential metal-based candidates for cancer treatment. However, the roles of cellular translocation in their action mechanisms remain elusive. Herein we present the synthesis and characterization of a series of ruthenium (Ru) complexes containing phenanthroline derivatives with varying lipophilicities, and examine their mechanism of anticancer action. Results showed that increasing the lipophilicity of complexes can enhance the rates of cellular uptake. The in vitro anticancer efficacy of these complexes depended on the levels of ROS overproduction, rather than on cellular Ru uptake levels. The introduction of a phenolic group on the ligand effectively enhanced their intracellular ROS generation and anticancer activities. In particular, complex 4, with an ortho-phenolic group on the ligand, exhibited better selectivity between cancer and normal cells in comparison with cisplatin. Notably, complex 4 entered the cancer cells partially through transferrin receptor-mediated endocytosis, and then it translocated from lysosomes to the mitochondria, where it activated mitochondrial dysfunction by regulation of Bcl-2 family proteins, thus leading to intracellular ROS overproduction. Excess ROS amplified apoptotic signals by activating many downstream pathways such as p53 and MAPK pathways to promote cell apoptosis. Overall, this study provides a drug design strategy for discovery of Ru-based apoptosis inducers, and elucidates the intracellular translocation of these complexes. Show less

We report herein a systematic study on interactions of organometallic ruthenium(II) anticancer complex [(η(6)-arene)Ru(en)Cl](+) (arene = p-cymene (1) or biphenyl (2), en = ethylenediamine) with human transferrin (hTf) and the effects of the hTf-ligation on the bioavailability of these complexes with cisplatin as a reference. Incubated with a 5-fold excess of complex 1, 2, or cisplatin, 1 mol of diferric hTf (holo-hTf) attached 0.62 mol of 1, 1.01 mol of 2, or 2.14 mol of cisplatin. Mass spectrometry revealed that both ruthenium complexes coordinated to N-donors His242, His273, His578, and His606, whereas cisplatin bound to O donors Tyr136 and Tyr317 and S-donor Met256 in addition to His273 and His578 on the surface of both apo- and holo-hTf. Moreover, cisplatin could bind to Thr457 within the C-lobe iron binding cleft of apo-hTf. Neither ruthenium nor platinum binding interfered with the recognition of holo-hTf by the transferrin receptor (TfR). The ruthenated/platinated holo-hTf complexes could be internalized via TfR-mediated endocytosis at a similar rate to that of holo-hTf itself. Moreover, the binding to holo-hTf well preserved the bioavailability of the ruthenium complexes, and the hTf-bound 1 and 2 showed a similar cytotoxicity toward the human breast cancer cell line MCF-7 to those of the complexes themselves. However, the conjugation with holo-hTf significantly reduced the cellular uptake of cisplatin and the amount of platinated DNA adducts formed intracellularly, leading to dramatic reduction of cisplatin cytotoxicity toward MCF-7. These findings suggest that hTf can serve as a mediator for the targeting delivery of Ru(arene) anticancer complexes while deactivating cisplatin. Show less

A series of ketone-N(4)-substituted thiosemicarbazone (TSC) compounds (L1-L9) and their corresponding [(η(6)-p-cymene)Ru(II)(TSC)Cl](+/0) complexes (1-9) were synthesized and characterized by NMR, IR, elemental analysis, and HR-ESI-mass spectrometry. The molecular structures of L4, L9, 1-6, and 9 were determined by single-crystal X-ray diffraction analysis. The compounds were further evaluated for their in vitro antiproliferative activities against the SGC-7901 human gastric cancer, BEL-7404 human liver cancer, and HEK-293T noncancerous cell lines. Furthermore, the interactions of the compounds with DNA were followed by electrophoretic mobility spectrometry studies. Show less

Ruthenium complexes are widely recognized as one of the most promising DNA damaging chemotherapeutic drugs. The main goal of this study was to explore the anticancer activity and underlying mechanisms of [Ru(phen)(2)(p-BrPIP)](ClO(4))(2), a novel chemically synthesized ruthenium (Ru) complex. To this end, we employed MTT assays to determine the anticancer activity of the complex, and performed single-cell gel electrophoresis (SCGE) and Western blotting to evaluate DNA damage. Our results showed that the Ru(II)-poly complex caused severe DNA damage, possibly by downregulating key factors involved in DNA repair pathways, such as proliferating cell nuclear antigen (PCNA) and ring finger protein 8 (RNF8). In addition, this complex induced cell apoptosis by upregulating both p21 and p53. Taken together, our findings demonstrate that the Ru(II)-poly complex exhibits antitumour activity by inducing cell apoptosis, which results from the accumulation of large amounts of unrepaired DNA damage. Show less

In the present study, the interaction between GC-rich sequence of bcl-2 gene P1 promoter (Pu39) and two ruthenium (II) polypyridyl complexes, [Ru(bpy)₂(tip)]²⁺ (1) and [Ru(phen)₂(tip)]²⁺ (2), was investigated by UV-Visible, fluorescence spectroscopy, circular dichroism, fluorescence resonance energy transfer melting assay and polymerase chain reaction stop assay. Those experimental results indicated that the two complexes can effectively stabilize the G-quadruplex of Pu39. It was found that the complex 2 exhibited greater cytotoxic activity than 1 against human Hela cells and can enter into Hela cells in a short period of time to effectively induce apoptosis of cells. Further experiments found that complexes 1 and 2 had as potent inhibitory effects on ECV-304 cell migration as suramin. Those noteworthy results provide new insights into the development of anticancer agents for targeting G-quadruplex DNA. Show less

Two ruthenium(II) complexes (Ru-complexes) were synthesized and characterized in this study. The selectivity and ability of the complexes to interact with bcl-2 DNA were investigated here. It turned out that [Ru(ip)3](ClO4)2·2H2O (complex 1, ip = 1H-iminazole [4,5-f][1,10] phenanthroline) could induce and stabilize the formations of G-quadruplexes more effectively than [Ru(pip)3](ClO4)2·2H2O (complex 2, pip = 2-phenylimidazo-[4,5-f][1,10]phenanthroline) did. Considering the important role of the Ru-complex ligand in inducing and stabilizing the formations of G-quadruplex in our previous studies, we speculate that the overlarge ligand of complex 2 may block its binding affinity for G-quadruplexes. Complex 1 also induced cell apoptosis in in vitro assays. In general, this study provided potentially important information for further development of the Ru-complexes as good inducers and stabilizers of bcl-2 G-quadruplex DNA for cancer treatment. Show less

The emission enhancement behavior and photocleavage activity of a ruthenium(II) arene complex, [(η(6)-p-cymene)Ru(dppn)(py)](2+) (1) (dppn = 4,5,9,16-tetraaza-dibenzo[a,c]naphthacene, py = pyridine), towards DNA were compared with [(η(6)-p-cymene)Ru(bpy)(py)](2+) (2), [Ru(bpy)2(dppz)](2+) (3) and [Ru(bpy)2(dppn)](2+) (4) (bpy = 2,2'-bipyridine, dppz = dipyrido-[3,2-a:2',3'-c]phenazine). It was found that 1 emits fluorescence from the dppn-based ligand-centered (LC) singlet excited state and generates singlet oxygen ((1)O2) from the dppn-based LC triplet excited state. As a result, 1 displays emission enhancement behavior and photocleavage activity towards DNA simultaneously. In contrast, 3 is the most classical DNA light switch but shows poor DNA photocleavage activity, while 4 is an efficient DNA photocleaver but cannot report DNA binding by luminescence enhancement. An increased cytotoxicity against human lung carcinoma cells A549 by about 10-fold was also observed for 1 upon visible light activation. These intriguing properties result from the unique combination of the Ru(II) arene and dppn subunits. Show less

The complexation with organoruthenium fragments confers 4-anilinoquinazoline pharmacophores with higher potential for inducing cellular apoptosis while the highly inhibitory activity of 4-anilinoquinazolines against EGFR and the reactivity of the ruthenium centre to 9-ethylguanine are well preserved. Show less

Two ruthenium(II) complexes [Ru(IP)2(PIP)](ClO4)2·2H2O (1) and [Ru(PIP)2(IP)](ClO4)2·2H2O (2) (IP=imidazole [4, 5-f] [1,10] phenanthroline, PIP=2-phenylimidazo-[4, 5-f][1,10] phenanthroline) have been synthesized and characterized. The quadruplex binding of the compounds was evaluated by emission spectrum, CD spectroscopy, Visual detection assay and FRET (fluorescence resonance energy transfer)-melting assay. The results show that both complexes can induce the stabilization of quadruplex DNA, while complex 1 is a better G-quadruplex binder than complex 2. Furthermore, polymerase chain reaction-stop assay, electrophoretic mobility shift assay, telomerase repeat amplification protocol and MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay demonstrate that complex 1 not only can stabilize dimer forms of the G-quadruplex at low concentrations but also exhibit better inhibitory activity for telomerase and cancer cells. Show less

Progress in an understanding of the genetic basis of cancer coupled to molecular pharmacology of potential new anticancer drugs calls for new approaches that are able to address key issues in the drug development process, including pharmacokinetic (PK) and pharmacodynamic (PD) relationships. The incorporation of predictive preclinical PK/PD models into rationally designed early-stage clinical trials offers a promising way to relieve a significant bottleneck in the drug discovery pipeline. The aim of the current review is to discuss some considerations for how quantitative PK and PD analyses for anticancer drugs may be conducted and integrated into a global translational effort, and the importance of examining drug disposition and dynamics in target tissues to support the development of preclinical PK/PD models that can be subsequently extrapolated to predict pharmacologic characteristics in patients. In this article, we describe three different physiologically based (PB) PK modeling approaches, i.e., the whole-body PBPK model, the hybrid PBPK model, and the two-pore model for macromolecules, as well as their applications. General conclusions are that greater effort should be made to generate more clinical data that could validate scaled preclinical PB-PK/PD tumor-based models and, thus, stimulate a framework for preclinical to clinical translation. Finally, given the innovative techniques to measure tissue drug concentrations and associated biomarkers of drug responses, development of predictive PK/PD models will become a standard approach for drug discovery and development. Show less

The platinum compound oxaliplatin has been shown to be an effective chemotherapeutic agent for the treatment of colorectal cancer. In this study, we investigate the molecular mechanisms of action of oxaliplatin to identify means of predicting response to this agent. Exposure of colon cancer cells to oxaliplatin resulted in G2/M arrest and apoptosis. Immunofluorescent staining demonstrated that the apoptotic cascade initiated by oxaliplatin is characterised by translocation of Bax to the mitochondria and cytochrome c release into the cytosol. Oxaliplatin treatment resulted in caspase 3 activation and oxaliplatin-induced apoptosis was abrogated by inhibition of caspase activity with z-VAD-fmk, but was independent of Fas/FasL association. Targeted inactivation of Bax or p53 in HCT116 cells resulted in significantly increased resistance to oxaliplatin. However, the mutational status of p53 was unable to predict response to oxaliplatin in a panel of 30 different colorectal cancer cell lines. In contrast, the expression profile of these 30 cell lines, assessed using a 9216-sequence cDNA microarray, successfully predicted the apoptotic response to oxaliplatin. A leave-one-out cross-validation approach was used to demonstrate a significant correlation between experimentally observed and expression profile predicted apoptosis in response to clinically achievable doses of oxaliplatin (R=0.53; P=0.002). In addition, these microarray experiments identified several genes involved in control of apoptosis and DNA damage repair that were significantly correlated with response to oxaliplatin. Show less