STING activation promotes robust immune response and NK cell-mediated tumor regression in glioblastoma models.

Immunotherapy has had a tremendous impact on cancer treatment in the past decade, with hitherto unseen responses at advanced and metastatic stages of the disease. However, the aggressive brain tumor glioblastoma (GBM) is highly immunosuppressive and remains largely refractory to current immunotherapeutic approaches. The stimulator of interferon genes (STING) DNA sensing pathway has emerged as a next-generation immunotherapy target with potent local immune stimulatory properties. Here, we investigated the status of the STING pathway in GBM and the modulation of the brain tumor microenvironment (TME) with the STING agonist ADU-S100. Our data reveal the presence of STING in human GBM specimens, where it stains strongly in the tumor vasculature. We show that human GBM explants can respond to STING agonist treatment by secretion of inflammatory cytokines. In murine GBM models, we show a profound shift in the tumor immune landscape after STING agonist treatment, with massive infiltration of the tumor-bearing hemisphere with innate immune cells including inflammatory macrophages, neutrophils, and natural killer (NK) populations. Treatment of established murine intracranial GL261 and CT-2A tumors by biodegradable ADU-S100-loaded intracranial implants demonstrated a significant increase in survival in both models and long-term survival with immune memory in GL261. Responses to treatment were abolished by NK cell depletion. This study reveals therapeutic potential and deep remodeling of the TME by STING activation in GBM and warrants further examination of STING agonists alone or in combination with other immunotherapies such as cancer vaccines, chimeric antigen receptor T cells, NK therapies, and immune checkpoint blockade.

Synthesis, characterization, and biological activity of cationic ruthenium-arene complexes with sulfur ligands.

Five cationic ruthenium-arene complexes with the generic formula [Ru(SAc)(S2C·NHC)(p-cymene)](PF6) (5a-e) were prepared in almost quantitative yields using a straightforward one-pot, two-step experimental procedure starting from [RuCl2(p-cymene)]2, an imidazol(in)ium-2-dithiocarboxylate (NHC·CS2) zwitterion, KSAc, and KPF6. These half-sandwich compounds were fully characterized by various analytical techniques and the molecular structures of two of them were solved by X-ray diffraction analysis, which revealed the existence of an intramolecular chalcogen bond between the oxygen atom of the thioacetate ligand and a proximal sulfur atom of the dithiocarboxylate unit. DFT calculations showed that the C=S…O charge transfer amounted to 2.4 kcal mol-1. The dissolution of [Ru(SAc)(S2C·IMes)(p-cymene)](PF6) (5a) in moist DMSO-d6 at room temperature did not cause the dissociation of its sulfur ligands. Instead, p-cymene was slowly released to afford the 12-electron [Ru(SAc)(S2C·IMes)]+ cation that could be detected by mass spectrometry. Monitoring the solvolysis process by 1H NMR spectroscopy showed that more than 22 days were needed to fully decompose the starting ruthenium-arene complex. Compounds 5a-e exhibited a high antiproliferative activity against human glioma Hs683 and human lung carcinoma A549 cancer cells. In particular, the IMes derivative (5a) was the most potent compound of the series, achieving toxicities similar to those displayed by marketed platinum drugs.

Pseudodiproline (Pro-Cyp) Oligomers Fold into Helical Polyproline Type secondary structures.

The synthesis and conformational properties of oligo-proline mimetics composed of dimeric and tetrameric Pro-Cyp constructs linked by a hydroxymethylene unit are reported. Oligomers were studied both in the solid state and in solution, unveiling right-handed helical conformation depending on the configuration of the vicinally substituted trans-cyclopentane carboxylic acid unit (Cyp). Unlike polyproline oligomers, the alternating synthetic Pro-Cyp counterparts are not stabilized by n-π* interactions but rely instead on the steric demands of the extended backbone conformation within the hydroxymethylene-linked Pro-Cyp repeating units.

Surprising Chemistry of 6-Azidotetrazolo[5,1-a]phthalazine: What a Purported Natural Product Reveals about the Polymorphism of Explosives.

6-Azidotetrazolo[5,1-a]phthalazine (ATPH) is a nitrogen-rich compound of surprisingly broad interest. It is purported to be a natural product, yet it is closely related to substances developed as explosives and is highly polymorphic despite having a nearly planar structure with little flexibility. Seven solid forms of ATPH have been characterized by single-crystal X-ray diffraction. The structures show diverse patterns of molecular organization, including both stacked sheets and herringbone packing. In all cases, N···N and C-H···N interactions play key roles in ensuring molecular cohesion. The high polymorphism of ATPH appears to arise in part from the ability of virtually every atom of nitrogen and hydrogen in the molecule to take part in close N···N and C-H···N contacts. As a result, adjacent molecules can adopt many different relative orientations that are energetically similar, thereby generating a polymorphic landscape with an unusually high density of potential structures. This landscape has been explored in detail by the computational prediction of crystal structures. Studying ATPH has provided insights into the field of energetic materials, where access to multiple polymorphs can be used to improve performance and clarify how it depends on molecular packing. In addition, our work with ATPH shows how valuable insights into molecular crystallization, often gleaned from statistical analyses of structural databases, can also come from in-depth empirical and theoretical studies of single compounds that show distinctive behavior.

Synthesis, structure and anticancer properties of new biotin- and morpholine-functionalized ruthenium and osmium half-sandwich complexes.

Ruthenium (Ru) and osmium (Os) complexes are of sustained interest in cancer research and may be alternative to platinum-based therapy. We detail here three new series of ruthenium and osmium complexes, supported by physico-chemical characterizations, including time-dependent density functional theory, a combined experimental and computational study on the aquation reactions and the nature of the metal-arene bond. Cytotoxic profiles were then evaluated on several cancer cell lines although with limited success. Further investigations were, however, performed on the most active series using a genetic approach based on RNA interference and highlighted a potential multi-target mechanism of action through topoisomerase II, mitotic spindle, HDAC and DNMT inhibition.

Reduction Mechanisms of Anticancer Osmium(VI) Complexes Revealed by Atomic Telemetry and Theoretical Calculations.

Resonant X-ray emission spectroscopy (RXES) has developed in the past decade as a powerful tool to probe the chemical state of a metal center and in situ study chemical reactions. We have used it to monitor spectral changes associated with the reduction of osmium(VI) nitrido complexes to the osmium(III) ammine state by the biologically relevant reducing agent, glutathione. RXES difference maps are consistent with the proposed DFT mechanism and the formation of two stable osmium(IV) intermediates, thereby supporting the overall pathway for the reduction of these high-valent anticancer metal complexes for which reduction by thiols within cells may be essential to the antiproliferative activity.

Design and Synthesis of Backbone-Fused, Conformationally Constrained Morpholine-Proline Chimeras.

We report the synthesis of two novel bridged morpholine-proline chimeras 4 and 5, which represent rigid conformationally locked three-dimensional structures wherein the lone pairs of electrons on oxygen and nitrogen are oriented in spatially different "east-west" and "north-west" directions, respectively. In combination with the presence of a carboxylic acid, the electronic features of these compounds may be useful in the context of peptidomimetic design of biologically relevant compounds. Quantitative estimates of the basicity of the nitrogen atoms were obtained using conceptual density functional theory analysis.

Speciation of Phenanthriplatin and Its Analogs in the Core of Tobacco Mosaic Virus.

Efficient loading of drugs in novel delivery agents has the potential to substantially improve therapy by targeting the diseased tissue while avoiding unwanted side effects. Here we report the first systematic study of the loading mechanism of phenanthriplatin and its analogs into tobacco mosaic virus (TMV), previously used by our group as an efficient carrier for anticancer drug delivery. A detailed investigation of the preferential uptake of phenanthriplatin in its aquated form (∼2000 molecules per TMV particle versus ∼1000 for the chlorido form) is provided. Whereas the net charge of phenanthriplatin analogs and their ionic mobilities have no effect on loading, the reactivity of aqua phenanthriplatin with the glutamates, lining the interior walls of the channel of TMV, has a pronounced effect on its loading. MALDI-MS analysis along with NMR spectroscopic studies of a model reaction of hydroxy-phenanthriplatin with acetate establish the formation of stable covalent adducts. The increased number of heteroaromatic rings on the platinum ligand appears to enhance loading, possibly by stabilizing hydrophobic stacking interactions with TMV core components, specifically Pro102 and Thr103 residues neighboring Glu97 and Glu106 in the channel. Electron transfer dissociation MS/MS fragmentation, a technique that can prevent mass-condition-vulnerable modification of proteins, reveals that Glu97 preferentially participates over Glu106 in covalent bond formation to the platinum center.

Strategies toward the Total Synthesis of Calyciphylline B-type Alkaloids: A Computational Perspective Aided by DFT Analysis.

Herein we describe synthetic efforts toward the total synthesis of calyciphylline B-type alkaloids. In the process, we disclose a detailed DFT study of equilibrium geometries and transition states that explains the stereochemical outcome during the formation of critical intermediates. X-ray crystallographic analysis reveals interesting conformational features in the naturally occurring deoxycalyciphylline B and its synthetic congeners.

Resonant X-ray emission spectroscopy of platinum(II) anticancer complexes.

Platinum-based drugs are commonly used in cancer treatment. The biological activity of a metallodrug is obviously closely related to its chemical and stereochemical characteristics. An overlooked aspect is the effect of the ligand to the electronic structure of the metal atom (coordinated atom). We report herein a Resonant X-ray Emission Spectroscopy (RXES) study on the chemical speciation of chiral platinum complexes in which diastereomers are distinguished on the basis of their metal electronic configuration. This demonstrates RXES high chemical speciation capabilities, a necessary property to further investigate the reactivity of the Pt atom towards nucleophiles or bionucleophiles, and an important complement the previously reported RXES abilities, namely that it can be employed for in situ studies at physiological concentrations.

Total Synthesis of Isodaphlongamine†H: A Possible Biogenetic Conundrum.

Herein we describe the first synthetic efforts toward the total synthesis of isodaphlongamine H, a calyciphylline B-type alkaloid. The strategy employs a chemoenzymatic process for the preparation of a functionalized cyclopentanol with a quaternary center. This molecule is elaborated to form an enantiopure 1-aza-perhydrocyclopentalene core, representing rings A and E of all calyciphylline B-type alkaloids. Further transformations involve the formation of a cyclic enaminone, 1,4-conjugate addition with a cyclopentenyl subunit, and intramolecular aldol cyclization to achieve a pentacyclic intermediate, ultimately forming isodaphlongamine H in a total of 24 steps from the commercially available compound 2-carbethoxycyclopentanone. Isodaphlongamine H exhibits promising inhibitory activity against a panel of human cancer cell lines.

Insights into the structure-activity relationships of chiral 1,2-diaminophenylalkane platinum(II) anticancer derivatives.

The structure-activity relationships of chiral 1,2-diaminophenylalkane platinum(II) anticancer derivatives are studied, including interactions with telomeric- and genomic-like DNA sequences, the pKa of their diaqua species, structural properties obtained from DFT calculations and resonant X-ray emission spectroscopy. The binding modes of the compounds to telomeric sequences were elucidated, showing no major differences with conventional cis-platinum(II) complexes like cisplatin, supporting that the cis-square planar geometry governs the binding of small Pt(II) complexes to G4 structures. Double-stranded DNA platination kinetics and acid-base constants of the diaqua species of the compounds were measured and compared, highlighting a strong steric dependence of the DNA-binding kinetics, but independent to stereoisomerism. Structural features of the compounds are discussed on the basis of dispersion-corrected DFT, showing that the most active series presents conformers for which the platinum atom is well devoid of steric hindrance. If reactivity indices derived from conceptual DFT do not show evidences for different reactivity between the compounds, RXES experiments provide new insight into the availability of platinum orbitals for binding to nucleophiles.

MybA1 gene diversity across the Vitis genus.

The MybA1 gene in the genus Vitis encodes a transcription factor, belonging to the R2R3 Myb family, that controls the last steps in the anthocyanins biosynthesis pathway. Polymorphism within MybA1 has been associated with color variation in berries of V. vinifera and other Vitis species. In this work, we analyzed the sequence variation in MybA1 both in the subg. Muscadinia and in an extended set of Asian, American and European genotypes of subg. Vitis. Our aims were to infer the evolution of this gene during the speciation process and to identify polymorphisms that could potentially generate changes in gene regulation. The results show that MybA1 experienced many insertions and deletions in non-coding regions but also in the third exon sequence. Owing to the larger set of Vitis species compared here, new indels were identified and the origin of previously described indels was reconsidered. A large number of single nucleotide polymorphisms were found in non-coding regions but also in the sequence coding for the R2R3 domain and the C terminal part of the protein. Some of these changes led to amino acid substitutions and therefore could have modified MybA1 protein activity. Bayesian phylogenetic analysis of all polymorphisms did not provide a consensus tree depicting the geographical partitioning of the species but allowed highlighting several species relationships within subgenus Vitis. Finally, the evolutionary events described could be useful to gain more insight into the role of MybA1 for anthocyanin biosynthesis in grapevine.

The use of Resonant X-ray Emission Spectroscopy (RXES) for the electronic analysis of metal complexes and their interactions with biomolecules.

This review presents a new application of Resonant X-ray Emission Spectroscopy (RXES) to study the mechanism of action of metal containing anticancer derivatives and in particular platinum in situ and in vivo. The technique is an example of a photon-in photon-out X-ray spectroscopic approach, which enables chemical speciation of drugs to be determined and therefore to derive action mechanisms, and to determine drug binding rates under physiological conditions and therapeutic concentrations. This is made feasible due to the atomic specificity and high penetration depth of RXES. The review presents examples of the three main types of information that can be obtained by RXES and establishes an experimental protocol to perfect the measurements within cells.

Structural Properties and Stereochemically Distinct Folding Preferences of 4,5-cis and trans-Methano-L-Proline Oligomers: The Shortest Crystalline PPII-Type Helical Proline-Derived Tetramer.

The synthesis, structural properties, and folding patterns of a series of L-proline methanologues represented by cis- and trans-4,5-methano-L-proline amides and their oligomers are reported as revealed by X-ray crystallography, circular dichroism measurements, and DFT calculations. We disclose the first example of a crystalline tetrameric proline congener to exhibit a polyproline II helical conformation. Experimental evidence of PPII-type helical arrangement (both in solution and in the solid state) of cis-4,5-methano-L-proline oligomers is supported by theoretical calculations reflecting the extent of n→π* stabilization of the trans-amide conformation.

Synthesis and in vitro characterization of platinum(II) anticancer coordinates using FTIR spectroscopy and NCI COMPARE: A fast method for new compound discovery.

Platinum-based drugs have been used for several decades to treat various cancers successfully. Cisplatin is the original compound in this class; it cross-links DNA, resulting in cell cycle arrest and cell death via apoptosis. Cisplatin is effective against several tumor types but exhibits toxic side effects; in addition, tumors often develop resistance. An original in vitro approach is proposed to determine whether platinum-based research compounds are good candidates for further study by comparing them to marketed drugs using FTIR spectroscopy and the COMPARE analysis from the NCI. Both methods can produce fingerprints and highlight differences between the compounds, classifying the candidates and revealing promising derivatives.

New stable QTLs for berry weight do not colocalize with QTLs for seed traits in cultivated grapevine (Vitis vinifera L.).

BACKGROUND: In grapevine, as in other fruit crops, fruit size and seed content are key components of yield and quality; however, very few Quantitative Trait Loci (QTLs) for berry weight and seed content (number, weight, and dry matter percentage) have been discovered so far. To identify new stable QTLs for marker-assisted selection and candidate gene identification, we performed simultaneous QTL detection in four mapping populations (seeded or seedless) with various genetic backgrounds. RESULTS: For berry weight, we identified five new QTLs, on linkage groups (LGs) 1, 8, 11, 17 and 18, in addition to the known major QTL on LG 18. The QTL with the largest effect explained up to 31% of total variance and was found in two genetically distant populations on LG 17, where it colocalized with a published putative domestication locus. For seed traits, besides the major QTLs on LG 18 previously reported, we found four new QTLs explaining up to 51% of total variance, on LGs 4, 5, 12 and 14. The previously published QTL for seed number on LG 2 was found related in fact to sex. We found colocalizations between seed and berry weight QTLs only for the major QTL on LG 18 in a seedless background, and on LGs 1 and 13 in a seeded background. Candidate genes belonging to the cell number regulator CNR or cytochrome P450 families were found under the berry weight QTLs on LGs 1, 8, and 17. The involvement of these gene families in fruit weight was first described in tomato using a QTL-cloning approach. Several other interesting candidate genes related to cell wall modifications, water import, auxin and ethylene signalling, transcription control, or organ identity were also found under berry weight QTLs. CONCLUSION: We discovered a total of nine new QTLs for berry weight or seed traits in grapevine, thereby increasing more than twofold the number of reliable QTLs for these traits available for marker assisted selection or candidate gene studies. The lack of colocalization between berry and seed QTLs suggests that these traits may be partly dissociated.

Species relationships within the genus Vitis based on molecular and morphological data.

The grape genus Vitis L. includes the domesticated V. vinifera, which is one of the most important fruit crop, and also close relatives recognized as valuable germplasm resources for improving cultivars. To resolve some standing problems in the species relationships within the Vitis genus we analyzed diversity in a set of 90 accessions comprising most of Vitis species and some putative hybrids. We discovered single nucleotide polymorphisms (SNPs) in SANGER sequences of twelve loci and genotyped accessions at a larger number of SNPs using a previously developed SNP array. Our phylogenic analyses consistently identified: three clades in North America, one in East Asia, and one in Europe corresponding to V. vinifera. Using heterozygosity measurement, haplotype reconstruction and chloroplast markers, we identified the hybrids existing within and between clades. The species relationships were better assessed after discarding these hybrids from analyses. We also studied the relationships between phylogeny and morphological traits and found that several traits significantly correlated with the phylogeny. The American clade that includes important species such as V. riparia and V. rupestris showed a major divergence with all other clades based on both DNA polymorphisms and morphological traits.

An anti-glioblastoma gold(i)-NHC complex distorts mitochondrial morphology and bioenergetics to induce tumor growth inhibition.

Glioblastoma multiforme (GBM) is the most lethal brain cancer subtype, often advanced by the time of initial diagnosis. Existing treatment modalities including surgery, chemotherapy and radiation have been stymied by recurrence, metastasis, drug resistance and brain targetability. Here, we report a geometrically distinct Au(i) complex ligated by N^N-bidentate ligands and supported by a N-heterocyclic ligand that modulates mitochondrial morphology to inhibit GBM in vitro and in vivo. This work benefits from the facile preparation of anti-GBM Au(i)-NHC complexes.

Stable Au(I) catalysts for oxidant-free C-H Functionalization with Iodoarenes.

The development of oxidant-free gold-catalyzed cross coupling reactions involving aryl halides have been hamstrung by the lack of gold catalysts capable of performing oxidative addition at Au(I) centers. Herein, we report the development of novel tricoordinate Au(I) catalysts supported by N,N-bidentate ligands and ligated by phosphine or arsine ligands for C-H functionalization without external oxidants to form biaryls with no homocoupling. The unsymmetrical character of the Au(I) catalyst is critical to facilitating this necessary orthogonal transformation. This study unveils yet another potential of Au(I) catalysis in biaryl synthesis.