Structural and functional analysis of cancer-associated missense variants in the retinoblastoma protein pocket domain.

The retinoblastoma tumor suppressor (Rb) is a multifunctional protein that primarily regulates the cell cycle but also has roles in cellular differentiation, DNA damage response, and apoptosis. The loss of Rb is a key event in the development or progression of many cancers. Essential functions of Rb occur through its pocket domain, which is necessary for regulating binding interactions with E2F transcription factors and transcription repressors that bind via an LxCxE motif.

Regulatory ligand binding in plant chalcone isomerase-like (CHIL) proteins.

Chalcone isomerase-like (CHIL) protein is a noncatalytic protein that enhances flavonoid content in green plants by serving as a metabolite binder and a rectifier of chalcone synthase (CHS). Rectification of CHS catalysis occurs through direct protein-protein interactions between CHIL and CHS, which alter CHS kinetics and product profiles, favoring naringenin chalcone (NC) production. These discoveries raise questions about how CHIL proteins interact structurally with metabolites and how CHIL-ligand interactions affect interactions with CHS.

Discovery of 6-[(3,4)-4-Amino-3-methyl-2-oxa-8-azaspiro[4.5]decan-8-yl]-3-(2,3-dichlorophenyl)-2-methyl-3,4-dihydropyrimidin-4-one (IACS-15414), a Potent and Orally Bioavailable SHP2 Inhibitor.

Src homology 2 (SH2) domain-containing phosphatase 2 (SHP2) plays a role in receptor tyrosine kinase (RTK), neurofibromin-1 (NF-1), and Kirsten rat sarcoma virus (KRAS) mutant-driven cancers, as well as in RTK-mediated resistance, making the identification of small-molecule therapeutics that interfere with its function of high interest. Our quest to identify potent, orally bioavailable, and safe SHP2 inhibitors led to the discovery of a promising series of pyrazolopyrimidinones that displayed excellent potency but had a suboptimal pharmacokinetic (PK) profile. Hypothesis-driven scaffold optimization led us to a series of pyrazolopyrazines with excellent PK properties across species but a narrow human Ether-à-go-go-Related Gene (hERG) window.

Discovery of IACS-9779 and IACS-70465 as Potent Inhibitors Targeting Indoleamine 2,3-Dioxygenase 1 (IDO1) Apoenzyme.

Indoleamine 2,3-dioxygenase 1 (IDO1), a heme-containing enzyme that mediates the rate-limiting step in the metabolism of l-tryptophan to kynurenine, has been widely explored as a potential immunotherapeutic target in oncology. We developed a class of inhibitors with a conformationally constrained bicyclo[3.1.

Entrustable Professional Activity-Based Summative Performance Assessment in the Surgery Clerkship.

Objective: The objectives of this study were to 1) assess the performance Entrustable Professional Activities (EPAs) when integrated into the summative assessment of third-year medical students on the surgery clerkship and 2) to compare EPAs to traditional clinical performance assessment tools.

Design: EPA assessments were collected prospectively from a minimum of 4 evaluators at the completion of each surgical clerkship rotation from November 2019 to June 2019. Overall EPA-based clinical performance scores were calculated as the sum of the mean EPA score from each evaluator.

Discovery of IPN60090, a Clinical Stage Selective Glutaminase-1 (GLS-1) Inhibitor with Excellent Pharmacokinetic and Physicochemical Properties.

Inhibition of glutaminase-1 (GLS-1) hampers the proliferation of tumor cells reliant on glutamine. Known glutaminase inhibitors have potential limitations, and in vivo exposures are potentially limited due to poor physicochemical properties. We initiated a GLS-1 inhibitor discovery program focused on optimizing physicochemical and pharmacokinetic properties, and have developed a new selective inhibitor, compound (IPN60090), which is currently in phase 1 clinical trials.

Allosteric SHP2 Inhibitor, IACS-13909, Overcomes EGFR-Dependent and EGFR-Independent Resistance Mechanisms toward Osimertinib.

Src homology 2 domain-containing phosphatase (SHP2) is a phosphatase that mediates signaling downstream of multiple receptor tyrosine kinases (RTK) and is required for full activation of the MAPK pathway. SHP2 inhibition has demonstrated tumor growth inhibition in RTK-activated cancers in preclinical studies. The long-term effectiveness of tyrosine kinase inhibitors such as the EGFR inhibitor (EGFRi), osimertinib, in non-small cell lung cancer (NSCLC) is limited by acquired resistance.

Discovery of IACS-9439, a Potent, Exquisitely Selective, and Orally Bioavailable Inhibitor of CSF1R.

Tumor-associated macrophages (TAMs) have a significant presence in the tumor stroma across multiple human malignancies and are believed to be beneficial to tumor growth. Targeting CSF1R has been proposed as a potential therapy to reduce TAMs, especially the protumor, immune-suppressive M2 TAMs. Additionally, the high expression of CSF1R on tumor cells has been associated with poor survival in certain cancers, suggesting tumor dependency and therefore a potential therapeutic target.

"Tandem" Nanomedicine Approach against Osteoclastogenesis: Polysulfide Micelles Synergically Scavenge ROS and Release Rapamycin.

We show the first example of a synergic approach of oxidant (ROS) scavenging carrier and ROS-responsive drug release in the context of a potential therapy against osteoporosis, aiming to inhibit the differentiation of inflammatory cells into osteoclasts. In our "tandem" approach, a branched amphiphilic, PEGylated polysulfide (PPSES-PEG) was preferred over a linear analogue, because of improved homogeneity in the aggregates (spherical micelles vs mixture of wormlike and spherical), increased stability, and higher drug loading (up to ∼22 wt % of antiosteoclastic rapamycin). These effects are ascribed to the branching inhibiting crystallization in the polysulfide blocks.

MPIC: Molecular Prognostic Indicators in Cirrhosis Database for Clinical Context-Specific Prognostic Biomarker Validation.

Prognostic biomarkers are vital in the management of progressive chronic diseases such as liver cirrhosis, affecting 1-2% of the global population and causing over 1 million deaths every year. Despite numerous candidate biomarkers in literature, the costly and lengthy process of validation hampers their clinical translation. Existing omics databases are not suitable for validation due to the ignorance of critical factors, i.

Strigolactone perception and deactivation by a hydrolase receptor DWARF14.

The perception mechanism for the strigolactone (SL) class of plant hormones has been a subject of debate because their receptor, DWARF14 (D14), is an α/β-hydrolase that can cleave SLs. Here we show via time-course analyses of SL binding and hydrolysis by Arabidopsis thaliana D14, that the level of uncleaved SL strongly correlates with the induction of the active signaling state. In addition, we show that an AtD14 catalytic mutant that lacks enzymatic activity is still able to complement the atd14 mutant phenotype in an SL-dependent manner.

Publisher Correction: Evolution of chalcone isomerase from a noncatalytic ancestor.

In the version of this article originally published, the number for the equal contributions footnote was missing for Miriam Kaltenbach and Jason R. Burke in the author list. The error has been corrected in the PDF and print versions of this article.

Evolution of chalcone isomerase from a noncatalytic ancestor.

The emergence of catalysis in a noncatalytic protein scaffold is a rare, unexplored event. Chalcone isomerase (CHI), a key enzyme in plant flavonoid biosynthesis, is presumed to have evolved from a nonenzymatic ancestor related to the widely distributed fatty-acid binding proteins (FAPs) and a plant protein family with no isomerase activity (CHILs). Ancestral inference supported the evolution of CHI from a protein lacking isomerase activity.

The Effect of Branching (Star Architecture) on Poly(d,l-lactide) (PDLLA) Degradation and Drug Delivery.

This study focuses on the comparative evaluation of star (branched) and linear poly(l,d-lactic acid) (PDLLA) as degradable materials employed in controlled release. The polymers were prepared via ring-opening polymerization initiated by decanol (linear), pentaerythritol (4-armed star) and dipentaerythritol (6-armed star), and processed both in the form of films and nanoparticles. Independent of the length or number of their arms, star polymers degrade slower than linear polymers, possibly through a surface (vs bulk) mechanism.

High π-Facial and exo-Selectivity for the Intramolecular Diels-Alder Cycloaddition of Dodeca-3,9,11-trien-5-one Precursors to 2-epi-Symbioimine and Related Compounds.

An unconstrained exocyclic stereogenic center and a removable trimethylsilyl group are combined to induce high π-facial selectivity and near-exclusive exo-selectivity in the intramolecular Diels-Alder cycloaddition of dodeca-3,9,11-trien-5-ones. This strategy provides direct access to polysubstituted trans-1-decalones related to the symbioimines in good yield and acceptable diastereoselectivity.

Branched polyesters: Preparative strategies and applications.

In the last 20years, the availability of precision chemical tools (e.g. controlled/living polymerizations, 'click' reactions) has determined a step change in the complexity of both the macromolecular architecture and the chemical functionality of biodegradable polyesters.

A Strategy for Direct Chemical Activation of the Retinoblastoma Protein.

The retinoblastoma (Rb) tumor suppressor protein negatively regulates cell proliferation by binding and inhibiting E2F transcription factors. Rb inactivation occurs in cancer cells upon cyclin-dependent kinase (Cdk) phosphorylation, which induces E2F release and activation of cell cycle genes. We present a strategy for activating phosphorylated Rb with molecules that bind Rb directly and enhance affinity for E2F.

Discovery of tricyclic indoles that potently inhibit Mcl-1 using fragment-based methods and structure-based design.

Myeloid cell leukemia-1 (Mcl-1) is an antiapoptotic member of the Bcl-2 family of proteins that is overexpressed and amplified in many cancers. Overexpression of Mcl-1 allows cancer cells to evade apoptosis and contributes to the resistance of cancer cells to be effectively treated with various chemotherapies. From an NMR-based screen of a large fragment library, several distinct chemical scaffolds that bind to Mcl-1 were discovered.

Multiple mechanisms for E2F binding inhibition by phosphorylation of the retinoblastoma protein C-terminal domain.

The retinoblastoma protein C-terminal domain (RbC) is necessary for the tumor suppressor protein's activities in growth suppression and E2F transcription factor inhibition. Cyclin-dependent kinase phosphorylation of RbC contributes to Rb inactivation and weakens the Rb-E2F inhibitory complex. Here we demonstrate two mechanisms for how RbC phosphorylation inhibits E2F binding.

Discovery of potent myeloid cell leukemia 1 (Mcl-1) inhibitors using fragment-based methods and structure-based design.

Myeloid cell leukemia 1 (Mcl-1), a member of the Bcl-2 family of proteins, is overexpressed and amplified in various cancers and promotes the aberrant survival of tumor cells that otherwise would undergo apoptosis. Here we describe the discovery of potent and selective Mcl-1 inhibitors using fragment-based methods and structure-based design. NMR-based screening of a large fragment library identified two chemically distinct hit series that bind to different sites on Mcl-1.

Structures of inactive retinoblastoma protein reveal multiple mechanisms for cell cycle control.

Cyclin-dependent kinase (Cdk) phosphorylation of the Retinoblastoma protein (Rb) drives cell proliferation through inhibition of Rb complexes with E2F transcription factors and other regulatory proteins. We present the first structures of phosphorylated Rb that reveal the mechanism of its inactivation. S608 phosphorylation orders a flexible "pocket" domain loop such that it mimics and directly blocks E2F transactivation domain (E2F(TD)) binding.

Crystal structure of the unliganded retinoblastoma protein pocket domain.

The retinoblastoma protein (Rb) regulates cell proliferation through its association with E2F transcription factors and other proteins. The Rb “pocket” domain primarily facilitates protein-protein interactions, and several structures of the pocket bound to E2F and tumorigenic viral proteins have been reported. We report here the first crystal structure of the pocket domain without bound ligand.

Novel 2,3,4,5-tetrahydro-benzo[d]azepine derivatives of 2,4-diaminopyrimidine, selective and orally bioavailable ALK inhibitors with antitumor efficacy in ALCL mouse models.

The synthesis and biological evaluation of potent and selective anaplastic lymphoma kinase (ALK) inhibitors from a novel class of 2,4-diaminopyrimidines, incorporating 2,3,4,5-tetrahydro-benzo[d]azepine fragments, is described. An orally bioavailable analogue (18) that displayed antitumor efficacy in ALCL xenograft models in mice was identified and extensively profiled.