Discovery of Highly Selective Inhibitors of Microtubule-Associated Serine/Threonine Kinase-like (MASTL).

By virtue of its role in cellular proliferation, microtubule-associated serine/threonine kinase-like (MASTL) represents a novel target and a first-in-class (FIC) opportunity to provide a new impactful therapeutic agent to oncology patients. Herein, we describe a hit-to-lead optimization effort that resulted in the delivery of two highly selective MASTL inhibitors. Key strategies leveraged to enable this work included structure-based drug design (SBDD), analysis of lipophilic efficiency (LipE) and novel synthesis.

Expanding control of the tumor cell cycle with a CDK2/4/6 inhibitor.

The CDK4/6 inhibitor, palbociclib (PAL), significantly improves progression-free survival in HR/HER2 breast cancer when combined with anti-hormonals. We sought to discover PAL resistance mechanisms in preclinical models and through analysis of clinical transcriptome specimens, which coalesced on induction of MYC oncogene and Cyclin E/CDK2 activity. We propose that targeting the G kinases CDK2, CDK4, and CDK6 with a small-molecule overcomes resistance to CDK4/6 inhibition.

Amantadine Inhibits SARS-CoV-2 In Vitro.

Since the SARS-CoV-2 pandemic started in late 2019, the search for protective vaccines and for drug treatments has become mandatory to fight the global health emergency. Travel restrictions, social distancing, and face masks are suitable counter measures, but may not bring the pandemic under control because people will inadvertently or at a certain degree of restriction severity or duration become incompliant with the regulations. Even if vaccines are approved, the need for antiviral agents against SARS-CoV-2 will persist.

PEGylated Cationic Serum Albumin for Boosting Retroviral Gene Transfer.

Retroviral vectors are common tools for introducing genes into the genome of a cell. However, low transduction rates are a major limitation in retroviral gene transfer, especially in clinical applications. We generated cationic human serum albumin (cHSA) protected by a shell of poly(ethylene glycol) (PEG); this significantly enhanced retroviral gene transduction with potentially attractive pharmacokinetics and low immunogenicity.

Efficacy of SERD/SERM Hybrid-CDK4/6 Inhibitor Combinations in Models of Endocrine Therapy-Resistant Breast Cancer.

Purpose: Endocrine therapy, using tamoxifen or an aromatase inhibitor, remains first-line therapy for the management of estrogen receptor (ESR1)-positive breast cancer. However, ESR1 mutations or other ligand-independent ESR1 activation mechanisms limit the duration of response. The clinical efficacy of fulvestrant, a selective estrogen receptor downregulator (SERD) that competitively inhibits agonist binding to ESR1 and triggers receptor downregulation, has confirmed that ESR1 frequently remains engaged in endocrine therapy-resistant cancers.

Axitinib and crizotinib combination therapy inhibits bone loss in a mouse model of castration resistant prostate cancer.

Background: Castration resistant prostate cancer (CRPC) is a leading cause of cancer-related deaths in men. The primary cause of mortality and morbidity in patients is bone metastases and remodeling resulting in osteoblastic and osteolytic lesions. Recently, cabozantinib, a multi-kinase inhibitor (VEGFR2 and c-MET inhibitor), was shown to have efficacy on bone lesions in patients.

Efficient delivery of p53 and cytochrome c by supramolecular assembly of a dendritic multi-domain delivery system.

Versatile nanocarrier systems facilitating uptake of exogenous proteins are highly alluring in evaluating these proteins for therapeutic applications. The self-assembly of an efficient nano-sized protein transporter consisting of three different entities is presented: A streptavidin protein core functioning as an adapter, second generation polyamidoamine dendrons for facilitating cell uptake as well as two different therapeutic proteins (tumor suppressor p53 or pro-apoptotic cytochrome c as cargo). Well-defined dendrons containing a biotin core are prepared and display no cytotoxic behavior upon conjugation to streptavidin.

A core-shell albumin copolymer nanotransporter for high capacity loading and two-step release of doxorubicin with enhanced anti-leukemia activity.

The native transportation protein serum albumin represents an attractive nano-sized transporter for drug delivery applications due to its beneficial safety profile. Existing albumin-based drug delivery systems are often limited by their low drug loading capacity as well as noticeable drug leakage into the blood circulation. Therefore, a unique albumin-derived core-shell doxorubicin (DOX) delivery system based on the protein denaturing-backfolding strategy was developed.

A quantum dot photoswitch for DNA detection, gene transfection, and live-cell imaging.

Quantum dots (QDs) coated with an albumin-derived copolymer shell exhibit significant photoresponsiveness to DNA loading and have great potential for investigating gene delivery processes. The QDs reported herein are positively charged, have attractive optical properties, and are noncytotoxic and notably stable in live cells. Their complex formation with plasmid DNA leads to proportionally decreased photoluminescence and efficient gene transfection is observed.

Convenient approach to polypeptide copolymers derived from native proteins.

A convenient approach for the synthesis of narrowly dispersed polypeptide copolymers of defined compositions is presented. The controlled denaturation of the proteins serum albumin and lysozyme followed by an in situ stabilization with polyethylene(oxide) chains yields polypeptide side chain copolymers of precisely defined backbone lengths as well as the presence of secondary structure elements. Supramolecular architectures are formed in solution because of the presence of hydrophobic and hydrophilic amino acids along the polypeptide main chain.

Bioactive unnatural somatostatin analogues through bioorthogonal iodo- and ethynyl-disulfide intercalators.

Iodo- and ethynyl-containing bisalkylating bioconjugation agents 5 and 8 were achieved and allow the introduction of reactive unnatural substituents into proteins and peptides whilst the bioactive 3D structure is retained. Derivatives of the peptide hormone somatostatin bearing a single iodo or ethynyl group were prepared through intercalation into the disulfide bridge. For the first time, the exact reaction mechanism of the intercalation was elucidated by applying 2D NMR experiments and it was shown that, during the reaction, somatostatin diastereomers were formed.

Tailored Albumin-based Copolymers for Receptor-Mediated Delivery of Perylenediimide Guest Molecules.

The synthesis of a novel and multifunctional copolymer based on a human serum albumin backbone bearing several folic acid as well as PEO groups was presented. In solution, this side-chain copolymer adopts a globular architecture and about five molecules of the water-insoluble chromophore PDI were successfully incorporated into these micelles for receptor-mediated cell uptake investigations. A significant uptake of these bioconjugates via receptor-mediated endocytosis was detected for cells expressing folic acid receptors in the cell membrane.

Studies on the dissociation of botulinum neurotoxin type A complexes.

Unlabelled: The neurotoxins produced by the various strains of the anaerobic bacterium Clostridium botulinum naturally occur associated with complexing proteins which serve to protect the neurotoxins from the harsh environment of the mammalian gastrointestinal tract during bacterial invasion of the host. Three different complex species with the discrete sizes 19S (900 kDa, LL complex), 16S (500 kDa, L complex) and 12S (300 kDa, M complex) may be isolated from C. botulinum type A cultures.

Cationized albumin-biocoatings for the immobilization of lipid vesicles.

Tethered lipid membranes or immobilized lipid vesicles are frequently used as biomimetic systems. In this article, the authors presented a suitable method for efficient immobilization of lipid vesicles onto a broad range of surfaces, enabling analysis by quantitative methods even under rigid, mechanical conditions-bare surfaces such as hydrophilic glass surfaces as well as hydrophobic polymer slides or metal surfaces such as gold. The immobilization of vesicles was based on the electrostatic interaction of zwitterionic or negatively charged lipid vesicles with two types of cationic chemically modified bovine serum albumin (cBSA) blood plasma proteins (cBSA-113 and cBSA-147).

cBSA-147 for the preparation of bacterial biofilms in a microchannel reactor.

Whole cells are attractive biocatalysts, particularly if the reaction requires cofactors or involves multiple transformations. Immobilization of the catalyst is often a prerequisite for continuous processes. The highly cationic chemically modified plasma protein bovine serum albumin (cBSA-147) has been applied for the electrostatically mediated immobilization of the planktonic bacterium E.

Fine-tuning DNA/albumin polyelectrolyte interactions to produce the efficient transfection agent cBSA-147.

We present the preparation and isolation of different chemically modified BSA species with varying numbers of primary amino groups at the surface. Highly cationic albumin proteins with increased numbers of amino groups were achieved and complex formation with plasmid DNA was carefully investigated. We compare the transfection results, polyelectrolyte complexes morphologies with their impact on complex stabilities, cytotoxicities and DNA accessibility.

Liver cell death and anemia in Wilson disease involve acid sphingomyelinase and ceramide.

Wilson disease is caused by accumulation of Cu(2+) in cells, which results in liver cirrhosis and, occasionally, anemia. Here, we show that Cu(2+) triggers hepatocyte apoptosis through activation of acid sphingomyelinase (Asm) and release of ceramide. Genetic deficiency or pharmacological inhibition of Asm prevented Cu(2+)-induced hepatocyte apoptosis and protected rats, genetically prone to develop Wilson disease, from acute hepatocyte death, liver failure and early death.

Stimulation of erythrocyte phosphatidylserine exposure by paclitaxel.

Side effects of cytostatic treatment include development of anemia resulting from either decreased generation or accelerated clearance of circulating erythrocytes. Recent experiments revealed a novel kind of stress-induced erythrocyte death, i.e.

Protein kinase C mediates erythrocyte "programmed cell death" following glucose depletion.

Glucose depletion of erythrocytes leads to activation of Ca2+-permeable cation channels, Ca2+ entry, activation of a Ca2+-sensitive erythrocyte scramblase, and subsequent exposure of phosphatidylserine at the erythrocyte surface. Ca2+ entry into erythrocytes was previously shown to be stimulated by phorbol esters and to be inhibited by staurosporine and chelerythrine and is thus thought to be regulated by protein phosphorylation/dephosphorylation, presumably via protein kinase C (PKC) and the corresponding phosphoserine/threonine phosphatases. The present experiments explored whether PKC could contribute to effects of energy depletion on erythrocyte phosphatidylserine exposure and cell volume.

Inhibition of erythrocyte "apoptosis" by catecholamines.

Osmotic shock, oxidative stress and Cl- removal activate a non-selective Ca2+-permeable cation conductance in human erythrocytes. The entry of Ca2+ leads to activation of a scramblase with subsequent exposure of phosphatidylserine at the cell surface. Phosphatidylserine mediates binding to phosphatidylserine receptors on macrophages which engulf and degrade phosphatidylserine exposing cells.

Phage release from biofilm and planktonic Staphylococcus aureus cells.

The ability of pathogenic staphylococci to form biofilms facilitates colonization and the development of chronic infections. Therapy is hampered by the high tolerance of biofilms towards antibiotic treatment and the immune system. We found evidence that lysogenic Staphylococcus aureus cells in a biofilm and in planktonic cultures spontaneously release phages into their surroundings.

Stimulation of erythrocyte phosphatidylserine exposure by mercury ions.

The sequelae of mercury intoxication include induction of apoptosis. In nucleated cells, Hg2+-induced apoptosis involves mitochondrial damage. The present study has been performed to elucidate effects of Hg2+ in erythrocytes which lack mitochondria but are able to undergo apoptosis-like alterations of the cell membrane.

Stimulation of erythrocyte ceramide formation by platelet-activating factor.

Osmotic erythrocyte shrinkage leads to activation of cation channels with subsequent Ca2+ entry and stimulates a sphingomyelinase with subsequent formation of ceramide. Ca2+ and ceramide then activate a scramblase leading to breakdown of phosphatidylserine asymmetry of the cell membrane. The mediators accounting for activation of erythrocyte sphingomyelinase and phosphatidylserine exposure remained elusive.

Stimulation of erythrocyte phosphatidylserine exposure by lead ions.

Pb+ intoxication causes anemia that is partially due to a decreased life span of circulating erythrocytes. As shown recently, a Ca(2+)-sensitive erythrocyte scramblase is activated by osmotic shock, oxidative stress, and/or energy depletion, leading to exposure of phosphatidylserine at the erythrocyte surface. Because macrophages are equipped with phosphatidylserine receptors, they bind, engulf, and degrade phosphatidylserine-exposing cells.

Analyzing changes of chromatin-bound replication proteins occurring in response to and after release from a hypoxic block of replicon initiation in T24 cells.

It was shown previously [Riedinger, H. J., van Betteraey-Nikoleit, M & Probst, H.