Pauline J. Wood

Inhibition of neutrophil infiltration into A549 lung tumors in vitro and in vivo using a CXCR2-specific antagonist is associated with reduced tumor growth.

Neutrophils are important innate immune cells that are involved in microbial clearance at sites of infection and in wound healing. The microenvironment of tumors often resembles that of chronic inflammation and increased numbers of neutrophils have been observed in several tumors and, in some cases, these positively correlate with poor prognosis. Neutrophil recruitment into tumors appears to be dependent on chemokines that bind to CXCR1 and CXCR2 expressed by neutrophils. In our study, we used lung adenocarcinoma A549 multicellular tumor spheroids and A549 tumor xenografts along with a CXCR2‐specific small molecule inhibitor (AZ10397767) to investigate the recruitment and function of human neutrophils in tumors. We found that A549 spheroids constitutively secrete high levels of CXCL chemokines and that neutrophil recruitment into A549 tumors in vitro and in vivo is largely dependent on CXCR2 activation. AZ10397767 significantly reduced the numbers of infiltrating neutrophils into both in vitro and in vivo tumor models, which was associated with slower growing tumors. Neutrophil infiltration into A549 tumor spheroids increased their size compared to noninfiltrated spheroids and neutrophil‐derived factors increased the proliferation of A549 tumor cells and induced endothelial cell tubule formation in vitro. In contrast, we saw no reduction in microvascular density in AZ10397767‐treated A549 tumors or in tumors grown in CXCR2−/− mice, suggesting that angiogenesis in these tumors is CXCR2‐independent. Our data show that neutrophils can contribute to lung tumor growth and that CXCR2 antagonists may be a useful therapeutic agent in the treatment of lung carcinomas.

Synthesis and Characterisation of Polyamine-Poly(ethylene glycol) Constructs for DNA Binding and Gene Delivery

Improved non-viral vector systems are needed for efficient delivery of DNA to target cell nuclei in gene therapy. A series of linear polyamine poly(ethylene glycol) (PEG) constructs has been synthesised by reaction of appropriately Boc-protected thermine derivatives with omega-methoxyPEG oxiranylmethyl ethers. Constructs carrying 1-3 MeOPEG units and 0, 2 or 4 N-methyl groups have been prepared by this method. H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NHBoc was prepared efficiently by mono-trifluoroacetylation of thermine, attachment of Boc and removal of the trifluoroacetyl group in one pot. A similar process gave H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NH2. BocMeN(CH2)3NHMe was alkylated by 1,3-dibromopropane to give BocMeN(CH2)3NMe(CH2)3NMe(CH2)3NMeBoc. A cyanoethylation/reduction sequence extended H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NH2 to give H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NBoc(CH2)3NBoc(CH2) 3NH2, which was converted to its mono- and di-MeOPEG550 derivatives. Deprotection gave the linear polyamine MeOPEG constructs. A branched triamine-poly(ethylene glycol) construct was prepared by acylation of (BocHN(CH2)3)2N(CH2)3NH2 with omega-methoxyPEG 550 chloroformate, followed by deprotection. A cyanoethylation/reduction/protection sequence from (H2N(CH2)3)2 N(CH2)3NHBoc gave a protected pentamine. Alkylation with Br(CH2)5CONH(CH2)2NHBoc, deprotection, acylation with MeOPEG chloroformate and deprotection gave a pentamine MeOPEG construct in which the MeOPEG is attached through a linker to the central amine. The linear hexamine construct carrying MeOPEG550 at only one terminus was the most effective DNA-interactive member of the two series in an ethidium displacement assay and was effective in delivering a reporter gene to RIF-1 tumours.

α-Methylacyl-CoA racemase (AMACR): Metabolic enzyme, drug metabolizer and cancer marker P504S

α-Methylacyl-CoA racemase (AMACR; P504S) catalyzes a key chiral inversion step in the metabolism of branched-chain fatty acids, ibuprofen and related drugs. Protein levels are increased in all prostate and some other cancer cells and it is used as a marker (P504S). The enzyme requires no cofactors and catalyzes its reaction by a stepwise 1,1-proton transfer via an enolate intermediate. The biological role of AMACR in cancer is complex, linking lipid metabolism with nuclear receptor (e.g. FXR and PPAR) activity and expression of enzymes such as cyclooxygenase-2 (COX-2). The roles of the various splice variants and the effects of single-nucleotide polymorphisms (SNPs) in cancers are discussed. A number of rationally designed AMACR inhibitors have been reported in the literature as potential cancer treatments. The opportunities and challenges for development of acyl-CoA esters as inhibitors are discussed from a medicinal chemical viewpoint. Other challenges for drug development include the problems in assaying enzymatic activity and the prediction of structure-activity relationships (SAR). Inhibitors of AMACR have potential to provide a novel treatment for castrate-resistant prostate cancers but this potential can only be realized once the biology is well understood. Recent work on the role of AMACR in parasitic diseases is also reviewed.

5-Benzamidoisoquinolin-1-ones and 5-(ω-Carboxyalkyl)isoquinolin-1-ones as Isoform-Selective Inhibitors of Poly(ADP-ribose) Polymerase 2 (PARP-2)

PARP-2 is a member of the poly(ADP-ribose) polymerase family, with some activities similar to those of PARP-1 but with other distinct roles. Two series of isoquinolin-1-ones were designed, synthesized, and evaluated as selective inhibitors of PARP-2, using the structures of the catalytic sites of the isoforms. A new efficient synthesis of 5-aminoisoquinolin-1-one was developed, and acylation with acyl chlorides gave 5-acylaminoisoquinolin-1-ones. By examination of isoquinolin-1-ones with carboxylates tethered to the 5-position, Heck coupling of 5-iodoisoquinolin-1-one furnished the 5-CH═CHCO(2)H compound for reduction to the 5-propanoic acid. Alkylation of 5-aminoisoquinolin-1-one under mildly basic conditions, followed by hydrolysis, gave 5-(carboxymethylamino)isoquinolin-1-one, whereas it was alkylated at 2-N with methyl propenoate and strong base. Compounds were assayed in vitro for inhibition of PARP-1 and PARP-2, using FlashPlate and solution-phase assays, respectively. The 5-benzamidoisoquinolin-1-ones were more selective for inhibition of PARP-2, whereas the 5-(ω-carboxyalkyl)isoquinolin-1-ones were less so. 5-Benzamidoisoquinolin-1-one is the most PARP-2-selective compound (IC(50(PARP-1))/IC(50(PARP-2)) = 9.3) to date, in a comparative study.

Structure-Based Design, Synthesis and Evaluation in Vitro of Arylnaphthyridinones, Arylpyridopyrimidinones and Their Tetrahydro Derivatives as Inhibitors of the Tankyrases.

The tankyrases are members of the PARP superfamily; they poly(ADP-ribosyl)ate their target proteins using NAD(+) as a source of electrophilic ADP-ribosyl units. The three principal protein substrates of the tankyrases (TRF1, NuMA and axin) are involved in replication of cancer cells; thus inhibitors of the tankyrases may have anticancer activity. Using structure-based drug design and by analogy with known 3-arylisoquinolin-1-one and 2-arylquinazolin-4-one inhibitors, series of arylnaphthyridinones, arylpyridinopyrimidinones and their tetrahydro-derivatives were synthesised and evaluated in vitro. 7-Aryl-1,6-naphthyridin-5-ones, 3-aryl-2,6-naphthyridin-1-ones and 3-aryl-2,7-naphthyridin-1-ones were prepared by acid-catalysed cyclisation of the corresponding arylethynylpyridinenitriles or reaction of bromopyridinecarboxylic acids with β-diketones, followed by treatment with NH3. The 7-aryl-1,6-naphthyridin-5-ones were methylated at 1-N and reduced to 7-aryl-1-methyl-1,2,3,4-tetrahydro-1,6-naphthyridin-5-ones. Cu-catalysed reaction of benzamidines with bromopyridinecarboxylic acids furnished 2-arylpyrido[2,3-d]pyrimidin-4-ones. Condensation of benzamidines with methyl 1-benzyl-4-oxopiperidine-3-carboxylate and deprotection gave 2-aryl-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidin-4-ones, aza analogues of the known inhibitor XAV939. Introduction of the ring-N in the arylnaphthyridinones and the arylpyridopyrimidinones caused >1000-fold loss in activity, compared with their carbocyclic isoquinolinone and quinazolinone analogues. However, the 7-aryl-1-methyl-1,2,3,4-tetrahydro-1,6-naphthyridin-5-ones showed excellent inhibition of the tankyrases, with some examples having IC50=2nM. One compound (7-(4-bromophenyl)-1-methyl-1,2,3,4-tetrahydro-1,6-naphthyridin-5-one) showed 70-fold selectivity for inhibition of tankyrase-2 versus tankyrase-1. The mode of binding was explored through crystal structures of inhibitors in complex with tankyrase-2.

Uptake and retention of nitroimidazole-carboranes designed for boron neutron capture therapy in experimental murine tumours : detection by 11B magnetic resonance spectroscopy

Two novel nitroimidazole-carboranes were examined for their uptake and retention in two experimental murine solid tumours and in some normal tissues, using in vivo 11B magnetic resonance spectroscopy. The compounds were injected i.p. at 0.8mmol/kg into mice bearing either the SCCVII/Ha squamous cell carcinoma or KHT sarcoma implanted intradermally on the mouse back. Boron from a polyether-isoxazole linked nitroimidazole-carborane (compound 1) was detectable in both SCCVII/Ha and KHT tumours at 3 and 7 h after injection. The signal from the liver at these times was greater than that from the tumour but only a weak signal was obtained from the brain. At 24 h after injection the tumour signal was still present, as was that from the liver, which appeared to have increased over that for the earlier times. Signal from the brain had disappeared by 24 h. Boron from a polyether-carbamate linked nitroimidazole-carborane (compound 2) was also detectable in both tumours at all times tested, and again was present in the liver. In addition, the 11B signal was detectable from the mouse brain, at early times, but was undetectable at 24 h. These preliminary data indicate that nitroimidazole-carboranes are taken up and retained in experimental murine tumours in sufficient amounts to be detectable by in vivo 11B MRS and further that at 24 h after treatment there is differential retention between tumours and the brain.

Synthesis and antiproliferative activity of some 3-(pyrid-2-yl)-pyrazolines

The synthesis and antiproliferative activity of eleven 3-(pyrid-2-yl)-pyrazolines in two cancer cell lines are reported. X-ray crystallography was obtained of the lead compound 8i which was screened in the NCI 60 human tumour cell line and displayed sub-micromolar activity. Cell cycle analysis, in vitro tubulin assay and confocal microscopy are also reported and suggest that the lead compound disrupts microtubule formation.

Exploration of the Nicotinamide-Binding Site of the Tankyrases, Identifying 3-Arylisoquinolin-1-Ones as Potent and Selective Inhibitors in Vitro.

Tankyrases-1 and -2 (TNKS-1 and TNKS-2) have three cellular roles which make them important targets in cancer. Using NAD(+) as a substrate, they poly(ADP-ribosyl)ate TRF1 (regulating lengths of telomeres), NuMA (facilitating mitosis) and axin (in wnt/β-catenin signalling). Using molecular modelling and the structure of the weak inhibitor 5-aminoiso quinolin-1-one, 3-aryl-5-substituted-isoquinolin-1-ones were designed as inhibitors to explore the structure-activity relationships (SARs) for binding and to define the shape of a hydrophobic cavity in the active site. 5-Amino-3-arylisoquinolinones were synthesised by Suzuki-Miyaura coupling of arylboronic acids to 3-bromo-1-methoxy-5-nitro-isoquinoline, reduction and O-demethylation. 3-Aryl-5-methylisoquinolin-1-ones, 3-aryl-5-fluoroisoquinolin-1-ones and 3-aryl-5-methoxyisoquinolin-1-ones were accessed by deprotonation of 3-substituted-N,N,2-trimethylbenzamides and quench with an appropriate benzonitrile. SAR around the isoquinolinone core showed that aryl was required at the 3-position, optimally with a para-substituent. Small meta-substituents were tolerated but groups in the ortho-positions reduced or abolished activity. This was not due to lack of coplanarity of the rings, as shown by the potency of 4,5-dimethyl-3-phenylisoquinolin-1-one. Methyl and methoxy were optimal at the 5-position. SAR was rationalised by modelling and by crystal structures of examples with TNKS-2. The 3-aryl unit was located in a large hydrophobic cavity and the para-substituents projected into a tunnel leading to the exterior. Potency against TNKS-1 paralleled potency against TNKS-2. Most inhibitors were highly selective for TNKSs over PARP-1 and PARP-2. A range of highly potent and selective inhibitors is now available for cellular studies.

Design, synthesis and antiproliferative activity of urocanic-chalcone hybrid derivatives

Inspired by biologically active natural products, a hybrid analogue that combines the N-Me urocanic side chain of the sarcodictyin family of compounds with the chalcone motif has been proposed, synthesised and examined for antiproliferative activity in three cancer cell lines and one normal primary cell line. The analogues are all synthesised in one or two steps from commercially available materials and, of the compounds examined, the proposed hybrid analogue displays the most active and selective inhibition of cell proliferation in human colon cancer cell line HT29 (IC50 2.9 μM) and highly metastatic human breast carcinoma MDA-MB-231 (IC50 4.8 μM).

The enone motif of (+)-grandifloracin is not essential for 'anti-austerity' antiproliferative activity.

We report the synthesis and biological evaluation of three analogues of the natural product (+)-grandifloracin (+)-1. All three analogues exhibit enhanced antiproliferative activity against PANC-1 and HT-29 cells compared to the natural product. The retention of activity in an analogue lacking the enone functional group, 9, implies this structural element is not an essential part of the (+)-grandifloracin pharmacophore.