▪ Abstract In the mid to late 1980s, studies were published that provided the first evidence for the existence of glutamate receptors that are not ligand-gated cation channels but are coupled to effector systems through GTP-binding proteins. Since those initial reports, tremendous progress has been made in characterizing these metabotropic glutamate receptors (mGluRs), including cloning and characterization of cDNA that encodes a family of eight mGluR subtypes, several of which have multiple splice variants. Also, tremendous progress has been made in developing new highly selective mGluR agonists and antagonists and toward determining the physiologic roles of the mGluRs in mammalian brain. These findings have exciting implications for drug development and suggest that the mGluRs provide a novel target for development of therepeutic agents that could have a significant impact on neuropharmacology.

Pharmacology and functions of metabotropic glutamate receptors.

AACR Centennial Conference: Translational Cancer Medicine-- Nov 4-8, 2007; Singapore

PL02-05 

All cancers are due to abnormalities in DNA. The availability of the human genome sequence has led to the proposal that resequencing of cancer genomes will reveal the full complement of somatic mutations and hence all the cancer genes. To explore the nature of the information that will be derived from cancer genome sequencing we have sequenced the coding exons of the family of 518 protein kinases, ~1.3Mb DNA per cancer sample, in 210 cancers of diverse histological types. Despite the screen being directed toward the coding regions of a gene family that has previously been strongly implicated in oncogenesis, the results indicate that the majority of somatic mutations detected are “passengers”. There is considerable variation in the number and pattern of these mutations between individual cancers, indicating substantial diversity of processes of molecular evolution between cancers. The imprints of exogenous mutagenic exposures, mutagenic treatment regimes and DNA repair defects can all be seen in the distinctive mutational signatures of individual cancers. This systematic mutation screen and others have previously yielded a number of cancer genes that are frequently mutated in one or more cancer types and which are now anticancer drug targets (for example BRAF , PIK3CA , and EGFR ). However, detailed analyses of the data from our screen additionally suggest that there exist a large number of additional “driver” mutations which are distributed across a substantial number of genes. It therefore appears that cells may be able to utilise mutations in a large repertoire of potential cancer genes to acquire the neoplastic phenotype. However, many of these genes are employed only infrequently. These findings may have implications for future anticancer drug development.

Patterns of Somatic Mutation in Human Cancer Genomes

Privileged substructures are of potentially great importance in medicinal chemistry. These scaffolds are characterized by their ability to promiscuously bind to a multitude of receptors through a variety of favorable characteristics. This may include presentation of their substituents in a spatially defined manner and perhaps also the ability to directly bind to the receptor itself, as well as exhibiting promising characteristics to aid bioavailability of the overall molecule. It is believed that some privileged substructures achieve this through the mimicry of common protein surface elements that are responsible for binding, such as β- and gamma;-turns. As a result, these structures represent a promising means by which new lead compounds may be identified.

The combinatorial synthesis of bicyclic privileged structures or privileged substructures

3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20874-922.pdf

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

The phosphoinositide 3-kinase (PI3K) pathway is a key signal transduction system that links oncogenes and multiple receptor classes to many essential cellular functions, and is perhaps the most commonly activated signalling pathway in human cancer. This pathway therefore presents both an opportunity and a challenge for cancer therapy. Even as inhibitors that target PI3K isoforms and other major nodes in the pathway, including AKT and mammalian target of rapamycin (mTOR), reach clinical trials, major issues remain. Here, we highlight recent progress that has been made in our understanding of the PI3K pathway and discuss the potential of and challenges for the development of therapeutic agents that target this pathway in cancer.

/pdf/targeting-the-phosphoinositide-3-kinase-pathway-in-cancer-4zhc81tbx0.pdf

Targeting the phosphoinositide 3-kinase pathway in cancer.

The isoxazoline route to the molecules of nature

(-)-Huperzine A (HupA) is found in an extract from a club moss that has been used for centuries in Chinese folk medicine. Its action has been attributed to its ability to strongly inhibit acetylcholinesterase (AChE). The crystal structure of the complex of AChE with optically pure HupA at 2.5 A resolution shows an unexpected orientation for the inhibitor with surprisingly few strong direct interactions with protein residues to explain its high affinity. This structure is compared to the native structure of AChE devoid of any inhibitor as determined to the same resolution. An analysis of the affinities of structural analogues of HupA, correlated with their interactions with the protein, shows the importance of individual hydrophobic interactions between HupA and aromatic residues in the active-site gorge of AChE.

Structure of acetylcholinesterase complexed with the nootropic alkaloid, (-)-huperzine A.

Alzheimer's disease (AD) characteristically presents with early memory loss. Regulation of K(+) channels, calcium homeostasis, and protein kinase C (PKC) activation are molecular events that have been implicated during associative memory which are also altered or defective in AD. PKC is also involved in the processing of the amyloid precursor protein (APP), a central element in AD pathophysiology. In previous studies, we demonstrated that benzolactam (BL), a novel PKC activator, reversed K(+) channels defects and enhanced secretion of APP alpha in AD cells. In this study we present data showing that another PKC activator, bryostatin 1, at subnanomolar concentrations dramatically enhances the secretion of the alpha-secretase product sAPP alpha in fibroblasts from AD patients. We also show that BL significantly increased the amount of sAPP alpha and reduced A beta 40 in the brains of APP[V717I] transgenic mice. In a more recently developed AD double-transgenic mouse, bryostatin was effective in reducing both brain A beta 40 and A beta 42. In addition, bryostatin ameliorated the rate of premature death and improved behavioral outcomes. Collectively, these data corroborate PKC and its activation as a potentially important means of ameliorating AD pathophysiology and perhaps cognitive impairment, thus offering a promising target for drug development. Because bryostatin 1 is devoid of tumor-promoting activity and is undergoing numerous clinical studies for cancer treatment in humans, it might be readily tested in patients as a potential therapeutic agent for Alzheimer's disease.

https://www.pnas.org/content/pnas/101/30/11141.full.pdf

Therapeutic effects of PKC activators in Alzheimer's disease transgenic mice.

Design of Remarkably Simple, Yet Potent Urea-Based Inhibitors of Glutamate Carboxypeptidase II (NAALADase)

Purpose: Previously, we showed successful imaging of xenografts that express the prostate-specific membrane antigen (PSMA) using small-animal positron emission tomography (PET) and the radiolabeled PSMA inhibitor N -[ N -[( S )-1,3-dicarboxypropyl]carbamoyl]- S -[ 11 C]methyl-l-cysteine. Herein, we extend that work by preparing and testing a PSMA inhibitor of the same class labeled with fluorine-18. Experimental Design: N -[ N -[( S )-1,3-Dicarboxypropyl]carbamoyl]-4-[ 18 F]fluorobenzyl-l-cysteine ([ 18 F]DCFBC) was prepared by reacting 4-[ 18 F]fluorobenzyl bromide with the precursor ( S )-2-[3-[( R )-1-carboxy-2-mercaptoethyl]ureido]-pentanedioic acid in ammonia-saturated methanol at 60°C for 10 min followed by purification using C-18 reverse-phase semipreparative high-performance liquid chromatography. Severe combined immunodeficient mice bearing a s.c. PSMA + PC-3 PIP tumor behind one shoulder and a PSMA − PC-3 FLU tumor behind the other shoulder were injected via the tail vein with either 1.85 MBq (50 μCi) of [ 18 F]DCFBC for ex vivo biodistribution or 7.4 MBq (200 μCi) for imaging. For biodistribution, mice were sacrificed at 5, 15, 30, 60, and 120 min. Tumor, blood, and major organs were harvested and weighed, and radioactivity was counted. Imaging was done on the GE eXplore Vista small-animal PET scanner by collecting 12 consecutive 10-min frames. Results: Radiochemical yield for [ 18 F]DCFBC averaged 16 ± 6% ( n = 8) from 4-[ 18 F]fluorobenzyl bromide. Specific radioactivities ranged from 13 to 133 GBq/μmol (350-3,600 Ci/mmol) with an average of 52 GBq/μmol (1,392 Ci/mmol; n = 6). Biodistribution and imaging studies showed high uptake of [ 18 F]DCFBC in the PIP tumors with little to no uptake in FLU tumors. High radiopharmaceutical uptake was also seen in kidneys and bladder; however, washout of radioactivity from these organs was faster than from the PIP tumors. The maximum PIP tumor uptake was 8.16 ± 2.55% injected dose per gram, achieved at 60 min after injection, which decreased to 4.69 ± 0.89 at 120 min. The PIP tumor to muscle ratio was 20 at 120 min after injection. Based on the mouse biodistribution, the dose-limiting organ is the kidneys (human estimated absorbed dose: 0.05 mGy/MBq; 0.2 rad/mCi). Conclusion: [ 18 F]DCFBC localizes to PSMA + -expressing tumors in mice, permitting imaging by small-animal PET. This new radiopharmaceutical is an attractive candidate for further studies of PET imaging of prostate cancer.

https://clincancerres.aacrjournals.org/content/clincanres/14/10/3036.full.pdf

Alan P. Kozikowski

Papers

The isoxazoline route to the molecules of nature

Structure of acetylcholinesterase complexed with the nootropic alkaloid, (-)-huperzine A.

Therapeutic effects of PKC activators in Alzheimer's disease transgenic mice.

Design of Remarkably Simple, Yet Potent Urea-Based Inhibitors of Glutamate Carboxypeptidase II (NAALADase)

N-[N-[(S)-1,3-Dicarboxypropyl]Carbamoyl]-4-[18F]Fluorobenzyl-l-Cysteine, [18F]DCFBC: A New Imaging Probe for Prostate Cancer