Yes / A series of ruthenium and iridium complexes have been synthesized and characterized with 20 novel crystal structures discussed. The library of β-ketoiminato complexes has been shown to be active against MCF-7 (human breast carcinoma), HT-29 (human colon carcinoma), A2780 (human ovarian carcinoma), and A2780cis (cisplatin-resistant human ovarian carcinoma) cell lines, with selected complexes’ being more than three times as active as cisplatin against the A2780cis cell line. Selected complexes were also tested against the noncancerous ARPE-19 (retinal pigment epithelial cells) cell line, in order to evaluate the complexes selectivity for cancer cells. Complexes have also been shown to be highly active under hypoxic conditions, with the activities of some complexes increasing with a decrease in O2 concentration. The enzyme thioredoxin reductase is overexpressed in cancer cells, and complexes reported herein have the advantage of inhibiting this enzyme, with IC50 values measured in the nanomolar range. The anticancer activity of these complexes was further investigated to determine whether activity is due to effects on cellular growth or cell survival. The complexes were found to induce significant levels of cancer cell death by apoptosis with levels induced correlating closely with activity in chemosensitivity studies. As a possible cause of cell death, the ability of the complexes to induce damage to cellular DNA was also assessed. The complexes failed to induce double-strand DNA breaks or DNA cross-linking but induced significant levels of single-strand DNA breaks, indicating a mechanism of action different from that of cisplatin. / Lord RM, Hebden AJ, Pask CM, Henderson IR, Allison SJ, Shepherd SL, Phillips RM, McGowan PC

No / Group IV metal complexes have previously shown promise as novel anticancer agents. Here, we discuss the mechanistic and cytotoxic nature of a series of group IV b-diketonate coordination complexes. Clear evidence that the ligands are exchangeable on the metal centre and that the b-diketonate ligands can act as potential drug delivery vehicles of the group IV metal ions was obtained. When evaluated for the cytotoxicity against human colon adenocarcinoma (HT-29) and human breast adenocarcinoma (MCF-7) cell lines, a general trend of decreasing potency down the group IV metals was observed. The most promising results obtained were for the hafnium complexes, with the tris diphenyl b-diketonate hafnium complex exhibiting IC50 values of 4.9 0.9 mm and 3.2 0.3 mm against HT-29 and MCF-7, respectively, which are comparable with the activity of cisplatin against the same cell lines. This tri b-diketonate hafnium complex is the first to show potent in vitro cytotoxic activity. The results reported show that ligand design has a significant effect on the cytotoxic potential of the complexes, and that these group IV complexes warrant further evaluation as novel metal-containing anticancer agents.

Yes / Condensation of a pyridyl-2-carbaldehyde derivative with 2-(bromoethyl)amine hydrobromide gave tetracyclic pyrido[1,2-a]pyrido[1’,2’:3,4]imidazo-[2,1-c]-6,7-dihydropyrazinium dications in excellent yields. Crystal structures and NOE data demonstrated the helical character of the dications, the dihedral angles between the two pyrido groups ranging from 28–458. An intermediate in the synthesis was also characterized. A much brighter emission compared to literature helicenes has been found, with quantum yields as high as 60% in the range of l=460– 600 nm. Preliminary cytotoxicity studies against HT-29 cancer cells demonstrated moderate-to-good activity, with IC50 values 12–30x that of cisplatin.

No / Most cancer cells use aerobic glycolysis to fuel their growth. The enzyme lactate dehydrogenase-A (LDH-A) is key to cancer’s glycolytic phenotype, catalysing the regeneration of nicotinamide adenine dinucleotide (NAD+) from reduced nicotinamide adenine dinucleotide (NADH) necessary to sustain glycolysis. As such, LDH-A is a promising target for anticancer therapy. Here we ask if the tumour suppressor p53, a major regulator of cellular metabolism, influences the response of cancer cells to LDH-A suppression. LDH-A knockdown by RNA interference (RNAi) induced cancer cell death in p53 wild-type, mutant and p53-null human cancer cell lines, indicating that endogenous LDH-A promotes cancer cell survival irrespective of cancer cell p53 status. Unexpectedly, however, we uncovered a novel role for p53 in the regulation of cancer cell NAD+ and its reduced form NADH. Thus, LDH-A silencing by RNAi, or its inhibition using a small-molecule inhibitor, resulted in a p53-dependent increase in the cancer cell ratio of NADH:NAD+. This effect was specific for p53+/+ cancer cells and correlated with (i) reduced activity of NAD+-dependent deacetylase sirtuin 1 (SIRT1) and (ii) an increase in acetylated p53, a known target of SIRT1 deacetylation activity. In addition, activation of the redox-sensitive anticancer drug EO9 was enhanced selectively in p53+/+ cancer cells, attributable to increased activity of NAD(P)H-dependent oxidoreductase NQO1 (NAD(P)H quinone oxidoreductase 1). Suppressing LDH-A increased EO9-induced DNA damage in p53+/+ cancer cells, but importantly had no additive effect in non-cancer cells. Our results identify a unique strategy by which the NADH/NAD+ cellular redox status can be modulated in a cancer-specific, p53-dependent manner and we show that this can impact upon the activity of important NAD(H)-dependent enzymes. To summarise, this work indicates two distinct mechanisms by which suppressing LDH-A could potentially be used to kill cancer cells selectively, (i) through induction of apoptosis, irrespective of cancer cell p53 status and (ii) as a part of a combinatorial approach with redox-sensitive anticancer drugs via a novel p53/NAD(H)-dependent mechanism.

Yes / The integrins are a family of 24 heterodimeric transmembrane cell surface receptors. Involvement in cell attachment to the extracellular matrix, motility, and proliferation identifies integrins as therapeutic targets in cancer and associated conditions; thrombosis, angiogenesis and osteoporosis. The most reported strategy for drug development is synthesis of an agent that is highly selective for a single integrin receptor. However, the ability of cancer cells to change their integrin repertoire in response to drug treatment renders this approach vulnerable to the development of resistance and paradoxical promotion of tumor growth. Here, we review progress towards development of antagonists targeting two or more members of the RGD-binding integrins, notably αvβ3, αvβ5, αvβ6, αvβ8, α5β1, and αIIbβ3, as anticancer therapeutics.

Yes / Platinum complexes are the most widely used anticancer drugs; however, new generations of agents are needed. The organoiridium(III) complex [(η5-Cpxbiph)Ir(phpy)(Cl)] (1-Cl), which contains π-bonded biphenyltetramethylcyclopentadienyl (Cpxbiph) and C^N-chelated phenylpyridine (phpy) ligands, undergoes rapid hydrolysis of the chlorido ligand. In contrast, the pyridine complex [(η5-Cpxbiph)Ir(phpy)(py)]+ (1-py) aquates slowly, and is more potent (in nanomolar amounts) than both 1-Cl and cisplatin towards a wide range of cancer cells. The pyridine ligand protects 1-py from rapid reaction with intracellular glutathione. The high potency of 1-py correlates with its ability to increase substantially the level of reactive oxygen species (ROS) in cancer cells. The unprecedented ability of these iridium complexes to generate H2O2 by catalytic hydride transfer from the coenzyme NADH to oxygen is demonstrated. Such organoiridium complexes are promising as a new generation of anticancer drugs for effective oxidant therapy. / We thank the ERC (247450), SNSF (PA00P2_145308 for N.P.E.B.), IAS (for I.R.C.), BBSRC (for J.M.H.), Science City (AWM and ERDF), and the EPSRC for support, and Prof. Timothy Bugg and members of EC COST Action CM1105 for stimulating discussions. We also thank Professor Pat Unwin, Mike Snowden, and Rob Lazenby for their help with the electrochemical experiments and the National Cancer Institute for NCI-60 human tumor cell panel screening.

Yes / Silane-substituted imidazotetrazines 1,2 were investigated for their activity as anticancer prodrugs related to temozolomide (TMZ). The TMS-derivative 1 showed an activity profile against TMZ susceptible and resistant cell lines very similar to TMZ; in contrast, the SEM-derivative 2 showed activity irrespective of MGMT expression or MMR deficiency (Table). Probing the prodrug activation mechanism by NMR kinetic studies determined that the TMS compound 1 follows a reaction pathway and time-course very similar to temozolomide. 1H-NMR spectra of the reaction mixture showed considerable incorporation of deuterium into the final alkylation products of the reaction (methanol and methyl phosphate) as had previously been shown for temozolomide (Wheelhouse, R.T., et al. Chem. Commun. 1993, 15, 1177–1178). The SEM-derivative 2 reacted more rapidly than TMZ or TMS-derivative 1. Somewhat surprisingly, the silane remained intact throughout the experiment and the observed reaction was the hydrolysis of the imidazo-tetrazine to ultimately release formaldehyde hydrate and 2-TMS-ethanol. In conclusion, TMS-derivative 1 is a diazomethane precursor with prodrug activation mechanism, kinetics and anti-cancer activity in vitro similar to TMZ. In contrast, the SEM derivative 2 was more rapidly hydrolysed, a precursor of 2-TMS-ethanol and had activity in vitro different from TMZ. 2-TMS-ethanol was previously reported as a non-toxic compound in mice (Voronkov, M.G., et al. Dokl. Akad. Nauk SSSR 1976, 229, 1011–1013) and is known as a substrate for alcohol dehydrogenase (Zong, M.-H., et al. Appl. Microbiol. Biotechnol. 1991, 36, 40–43) and as a modest inhibitor of acetylcholinesterase (Aberman, A., et al. Biochim. Biophys. Acta 1984, 791, 278–280; Cohen, S.G., et al. J. Med. Chem. 1985, 28, 1309–1313).

Yes / The synthesis, characterisation and evaluation of the in vitro cytotoxicity of four indole-based half-sandwich metal complexes towards two ovarian cancer cell lines (A2780 and A2780cisR) and one normal prostate cell line (PNT2) are presented herein. Although capable of inducing catalytic oxidation of NADH and able to reduce NAD+ with high turnover frequencies, in cells and in the presence of sodium formate, these complexes also strongly interact with biomolecules such as glutathione. This work highlights that efficient out-of-cells catalytic activity might lead to higher reactivity towards biomolecules, thus inhibiting the in-cells catalytic processes.

Les phosphinosucres appelés aussi « phostines » sont des analogues phosphorés des sucres pyranoses et des C-arylglycosides. L'évaluation biologique de ses composés a révélé une activité anticancéreuse des phosphinosucres sur les cellules de glioblastome multiforme, un cancer particulièrement malin et invasif qui ne possède pas de solution thérapeutique. Dans le but de comprendre les mécanismes d'action des phosphinosucres et la stéréo-dépendance de leur activité biologique, la caractérisation des diastéréomères de « phostines » a été menée. Suite à cette détermination structurale, le développement de synthèses diastéréosélectives a permis d'obtenir un mélange fortement enrichi en diastéréomère le plus actif par une séquence réactionnelle qui a mis en jeu une réaction d'oxydation de phosphinosucres -hydroxylés en α-cétophosphinosucres, suivie d'une réduction diastéréosélective. Afin d'améliorer l'activité antiproliférative des phosphinosucres, une diversification chimique a été réalisée. Les variations du groupement aryle lié à l'atome de phosphore nous ont amené à développer une synthèse des aryl-hydrogénophosphinates qui a permis d'obtenir une large variété de ces composés. Par la suite, les aryl-hydrogénophosphinates obtenus ont été engagés dans la synthèse des « phostines ». De plus, des variations chimiques sur le carbone en position α de l'atome de phosphore ont été entreprises et ont permis l'élaboration de plusieurs composés (triflate, azido, amino, déoxy et triazolyles), puis finalement à l'analogue phosphinosucre du N-acétylglucosamine qui a présenté une importante activité anticancéreuse in vitro. / Phosphinosugars also called « phostines » are new cyclic phosphinates, analogs of carbohydrates and C-aryglycosides, with phosphorus atom mimicking the anomeric carbon. Biological screening tests of these compounds revealed an anticancer activity against glioblastoma multiform, a highly invasive and malignant tumor without curative therapy.With the aim of understanding the phosphinosugars mode of action and their stereo-dependent biological activity, characterization of four phosphinosugars diastereomers formed during the chemical process has been performed. After their structural determination, diastereoselective synthesis enabled us to obtain an enriched mixture of the most active diastereomer based on an oxidation of -hydroxyled phosphinosugars in corresponding -keto phosphinosugars followed by a diastereoselective reduction. Thereafter, antiproliferative activity of phoshinosugars was performed by chemical diversification. Modification of the aryl group linked to phosphorus atom led us to develop aryl-hydrogenophosphinate synthesis to create a broad variety of these structures. Then, the expected aryl-hydrogenophosphinates were used for phostines preparation. Furthermore, chemical modifications on the carbon in α position of phosphorus atom were led and furnished several new compounds (triflate, azido, amino, deoxy and triazolyl), as well as the phosphinosugar analog of N-acetylglucosamine which presented in vitro a high anticancer activity.

Solanum lycocarpum A. St.-Hil. (Solanaceae Solanum), popular lobeira, é espécie arbustiva nativa e característica do Cerrado brasileiro. Seus frutos são empregados na medicina caseira como diurética, calmante, anti-espasmódica, antiofídica e antiepilética. As espécies do gênero Solanum são produtoras de heterosídeos alcaloídicos, os quais possuem atividade antitumoral, incluindo-se anticâncer de pele. O câncer de pele tem preocupado as autoridades no mundo com os crescentes índices atuais e, por esse motivo, a busca por novos ativos anticâncer é primordial. Dos frutos da lobeira, pode-se produzir extrato alcaloídico, o qual se constitui de uma mistura de glicoalcalóides composta majoritariamente de solasonina e solamargina. Tais compostos têm sido estudados quanto ao potencial anticancerígeno, são relativamente seletivos para células tumorais e, em consequência, apresentam baixa toxicidade às células sadias. Por estes motivos, o potencial antitumoral desta espécie deve ser investigado. Para isso, os frutos foram coletados, secos e triturados. A droga vegetal resultante foi submetida à extração tipo ácido-base para obtenção do extrato alcaloídico. O método analítico empregado para quantificação dos heterosídeos alcaloídicos foi desenvolvida e validada em CLAE-UV. A partir do extrato alcaloídico padronizado, foram desenvolvidas formulações para uso tópico. Estas formulações foram avaliadas por meio de ensaios de permeação e retenção dérmica in vitro, cujo método analítico para quantificação de solasonina e solamargina foi validado. Para escolha da formulação mais promissora para ensaio anticâncer in vivo, as formulações de melhor desempenho in vitro foram avaliadas quanto à retenção dérmica in vivo em camundongos hairless. A formulação B, contendo 1% de extrato alcaloídico, 5% de monoleína (monoleato de glicerol), 5% de propilenoglicol em base de gel de Natrosol (pH 6,5), apresentou retenção dérmica total adequada para futuros ensaios anticâncer de pele in vivo. / Solanum lycocarpum A. St.-Hil. (Solanaceae - Solanum), popular wolf-fruit is a native shrub species and characteristic of the Brazilian Cerrado vegetation. Its fruits are used in folk medicine as diuretic, sedative, anti-spasmodic, antiepileptic and antiophidic. This species belongs to the genus Solanum, known to produce alkaloid heterosides, which possess antitumor activity, including skin anticancer. Skin cancer has concerned the authorities in the world because of its growing rates. Therefore, the search for new active anticancer is paramount. The wolf-fruit furnish an alkaloidic extract, which is rich in a mixture of heteroside alkaloids and composed mostly of solasonine and solamargine. Such compounds have been studied as potential anticancer, because they are relatively selective for tumor cells and, consequently, have low toxicity to health cell. For these reasons, the antitumor potential of this species should be investigated. For that, the fruits were collected, dried and crushed. The dried plant biomass was submitted to acid-base extraction to obtain the alkaloidic extract. The analytical method for the quantitation of the alkaloids in both crude alkaloid extract and plant biomass was developed and validated by HPLC-UV. From the alkaloidic extract, formulations were developed for topical use. These formulations were evaluated by in vitro tests of skin permeation and retention in Franz diffusion cell, for which an analytical method for quantifying solasonine and solamargine was developed, as well. The selection of the most promising formulation for anticancer assay in vivo was based in both, the permeation performance of the formulation in vitro and its skin retention in vivo in hairless health mice. The formulation B, containing crude alkaloid extract 1%, Monoolein 5%, propyleneglycol 5% in Natrosol gel (pH 6.5), showed total dermal retention, which is suitable for future trials of skin anticancer in animal models.