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In order to optimize the potency of the first serum-stable peptide agonist of CD47 (PKHB1) in triggering regulated cell death of cancer cells, we designed a maturation process aimed to mimic the trimeric structure of the thrombospondin-1/CD47 binding epitope. For that purpose, an N-methylation scan of the PKHB1 sequence was realized to prevent peptide aggregation. Structural and pharmacological analyses were conducted in order to assess the conformational impact of these chemical modifications on the backbone structure and the biological activity. This structure–activity relationship study led to the discovery of a highly soluble N-methylated peptide that we termed PKT16. Afterward, this monomer was used for the design of a homotrimeric peptide mimic that we termed [PKT16]3, which proved to be 10-fold more potent than its monomeric counterpart. A pharmacological evaluation of [PKT16]3in inducing cell death of adherent (A549) and nonadherent (MEC-1) cancer cell lines was also performed.

Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia in Western countries, is a very heterogeneous disease characterized by a peripheral accumulation of abnormal CD5+ B lymphocytes in the immune system. Despite new therapeutic developments, there remains an unmet medical need for CLL. Here, we demonstrate that the use of N-methylated thrombospondin-1 (TSP-1)–derived peptides is an efficient way to kill the malignant CLL cells, including those from high-risk individuals with poor clinical prognosis, del11q, del17p, 2p gain, or complex karyotype. PKT16, our hit N-methylated peptide, triggers the elimination of the leukemic cells, sparing the nontumor cells, including the hematopoietic precursors, and reduces the in vivo tumor burden of a CLL-xenograft mice model. A complementary analysis underscores the improved cytotoxic efficiency of PKT16 compared with the previously described TSP-1–derived probes, such as PKHB1. PKT16 elicits an original caspase-independent programmed necrotic mode of cell death, different from necroptosis or ferroptosis, implicating an intracellular Ca2+ deregulation that provokes mitochondrial damage, cell cycle arrest, and the specific death of the malignant CLL cells. The activation of the Gαi proteins and the subsequent drop of cyclic adenosine monophosphate levels and protein kinase A activity regulate this cytotoxic cascade. Remarkably, PKT16 induces the molecular hallmarks of immunogenic cell death, as defined by the calreticulin plasma membrane exposure and the release of adenosine triphosphate and high-mobility group box 1 protein from the dying CLL cells. Thus, PKT16 appears to be able to stimulate an anticancer in vivo immune response. Collectively, our results pave the way toward the development of an efficient strategy against CLL.

The document presents two separate articles with the same title –“What is HamasteghtsakanArt” – by artist Arman Grigoryan and art critic Nazareth Karoyan, published in Armenia in 1994 and 1996 respectively. Translated from Armenian and introduced by Angela Harutyunyan both articles have been formative for the development of contemporary art in Armenia. While presenting diverging views on the meaning of hamasteghtsakan(translated as collectively created), the concept was circulated as a definition for a broad range of post-medium artistic practices in late Soviet and post-Soviet Armenia. These practices formed an oppositional discourse to both Socialist Realism and Armenian National modernism. Harutyunyan's introduction locates the texts in a broader context of artistic institutional transformations in the late 1980s and early 1994 in Armenia.

ABSTRACTBreast cancer is the most commonly diagnosed cancer and the leading cause of cancer death in women worldwide. Recent advances in the field of immuno-oncology demonstrate the beneficial immunostimulatory effects of the induction of immunogenic cell death (ICD). ICD increases tumor infiltration by T cells and is associated with improved prognosis in patients affected by triple negative breast cancer (TNBC) with residual disease. The aim of this study was to evaluate the antitumoral effect of PKHB1, a thrombospondin-1 peptide mimic, against breast cancer cells, and the immunogenicity of the cell death induced by PKHB1 in vitro, ex vivo, and in vivo. Our results showed that PKHB1 induces mitochondrial alterations, ROS production, intracellular Ca2+accumulation, as well calcium-dependent cell death in breast cancer cells, including triple negative subtypes. PKHB1 has antitumor effect in vivo leading to a reduction of tumor volume and weight and promotes intratumoral CD8 + T cell infiltration. Furthermore, in vitro, PKHB1 induces calreticulin (CALR), HSP70, and HSP90 exposure and release of ATP and HMGB1. Additionally, the killed cells obtained after treatment with PKHB1 (PKHB1-KC) induced dendritic cell maturation, and T cell antitumor responses, ex vivo. Moreover, PKHB1-KC in vivo were able to induce an antitumor response against breast cancer cells in a prophylactic application, whereas in a therapeutic setting, PKHB1-KC induced tumor regression; both applications induced a long-term antitumor response. Altogether our data shows that PKHB1, a thrombospondin-1 peptide mimic, has in vivo antitumor effect and induce immune system activation through immunogenic cell death induction in breast cancer cells.

We report on the characteristics of the radical‐ion‐driven dissociation of a diverse array of β‐amino acids incorporated into α‐peptides, as probed by tandem electron‐capture and electron‐transfer dissociation (ECD/ETD) mass spectrometry. The reported results demonstrate a stronger ECD/ETD dependence on the nature of the amino acid side chain for β‐amino acids than for their α‐form counterparts. In particular, only aromatic (e.g., β‐Phe), and to a substantially lower extent, carbonyl‐containing (e.g., β‐Glu and β‐Gln) amino acid side chains, lead to NCβbond cleavage in the corresponding β‐amino acids. We conclude that radical stabilization must be provided by the side chain to enable the radical‐driven fragmentation from the nearby backbone carbonyl carbon to proceed. In contrast with the cleavage of backbones derived from α‐amino acids, ECD of peptides composed mainly of β‐amino acids reveals a shift in cleavage priority from the NCβto the CαC bond. The incorporation of CH2groups into the peptide backbone may thus drastically influence the backbone charge solvation preference. The characteristics of radical‐driven β‐amino acid dissociation described herein are of particular importance to methods development, applications in peptide sequencing, and peptide and protein modification (e.g., deamidation and isomerization) analysis in life science research.

Benzylpyridinium ions are often used as ‘thermometer ions’ in order to evaluate the internal energy distribution of the ions formed in sources of mass spectrometers. However, the detailed fragmentation pathways of these parent ions were not well established. In particular, fragmentation involving a rearrangement RR process may be influencing the simulated distribution curves. In a previous study, we suggested that such RR actually occurred under electrospray ionizationmass spectrometry ESIMS and fast atom bombardmentmass spectrometry FABMS experiments. Here, we present a systematic study of different substituted benzylpyridinium ions. Theoretical calculations showed that RR fragmentation leading to substituted tropylium ions could occur under ‘soft ionization’ conditions, such as ESI or FAB. Experimental results obtained under gasphase reactivity conditions showed that some substituted benzylpiridinium compounds actually undergo RR fragmentations under ESIMS conditions. Massanalyzed kinetic experiments were also carried out to gain information on the reaction pathways that actually occur, and these experimental results are in agreement with the reaction pathways theoretically proposed. Copyright © 2009 John Wiley & Sons, Ltd.

A simple and stereoselective method for the preparation of Z2substituted 1aminocyclopropanecarboxylic acids is described. The common key step for these reaction sequences involves the stereoselective Timediated coupling of benzyloxy nitrile and homoallylic alcohol. The resulting 2hydroxyethylsubstituted cyclopropylamine can be transformed shortly into various cyclopropane amino acid analogues on the gram scale, in good overall yields. Several syntheses of 2,3methanoamino acids, that is, ACCs derived from proteinogenic αamino acids or analogues, such as glutamic acid, arginine, homoarginine, and lysine derivatives are presented to exemplify the usefulness of the method. Additionally, starting from cyanoesters, spirocyclopropane γamino acid analogues are available in this way. © WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Numerous backbone constraints can be used to develop pseudopeptides or pseudomimetics of biologically active peptides. Among those, N- and C-methyl amino acids that can be incorporated by solidphase peptide synthesis in a bioactive sequence represent important tools to restrict and angles of peptide backbone. This review will focus on the chemical syntheses of N- and C-methyl amino acids, their effects on peptide conformation and structure, and their role on the peptide stability towards enzymatic degradation and on the biological activities of the resulting analogues.

Preparation of 3-substituted prolines was achieved by extension to Solid Phase Organic Synthesis (SPOS) of the amino-zinc-enolate cyclization we have recently described. 1Functionalizations of proline at C-3 were considered by nucleophilic substitutions of an iodo derivative obtained on the resin.

Two binding sites are associated with neurokinin-1 substance P receptors in both transfected cells and mammalian tissues. To further delineate the interactions between the crucial C-terminal methionine of substance P and these two binding sites, we have incorporated newly designed constrained methionines, i.e.(2 S, 3 S)- and (2 S,3 R)-prolinomethionines. The potencies of these C terminus-modified SP analogues to bind both sites and to activate phosphatidylinositol hydrolysis and cAMP formation have been measured, together with those of their corresponding sulfoxides and sulfones. The molecular nature of these two binding sites and their selective coupling to effector signaling pathways are discussed in the light of current models of receptor activation. The less abundant binding site is coupled to Gq/11proteins, whereas the most abundant one interacts with Gsproteins in Chinese hamster ovary cells transfected with human neurokinin-1 receptors. The specific orientation of the C-terminal methionine side chain imposed by these constraints shows that macroscopically χ1and χ2angles of this crucial C-terminal residue are similar in both binding sites. However, slight but significant variations in the rotation around the Cγ–S bond yield different either stabilizing or destabilizing interactions in the two binding sites. These results highlight the need of such constrained amino acids to probe subtle interactions in ligand-receptor complexes.

Ring formation involving a 5-exo trig cyclization between a zinc enolate and a non activated double bond led to cis diastereoisomer of 3-substituted prolines. This cyclization was achieved with transfer of chirality onto the C-2 carbon when nitrogen was protected by an α-methylbenzyl group. Reprotonation of the lithium enolate of cis derivative yielded the trans diastereoisomer.

The asymmetric synthesis of (S)-Boc-N-methyl-p-benzoyl-phenylalanine was performed by alkylation of sultam Boc-sarcosinate. The levorotatory sultam led to (S)-Boc-N-methyl amino acids with high optical purity. This photoreactive amino acid was incorporated into the sequence of a Substance P peptide antagonist. Comparison of the affinity and antagonistic properties of Biotinyl-apa-[D-Pro9, MePhe(pBz)10, Trp11]SP for human tachykinin NK-1 receptor demonstrated that this photoreactive antagonist should be a suitable tool for photolabelling studies.