SIRT1 ISGylation accelerates tumor progression by unleashing SIRT1 from the inactive state to promote its deacetylase activity.

ISG15 is an interferon-stimulated ubiquitin-like protein (UBL) with multifaceted roles as a posttranslational modifier in ISG15 conjugation (ISGylation). However, the mechanistic consequences of ISGylation in cancer have not been fully elucidated, largely due to a lack of knowledge on the ISG15 target repertoire. Here, we identified SIRT1, a nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase, as a new target for ISGylation. SIRT1 ISGylation impairs the association of SIRT1 with its negative regulator, deleted in breast cancer 1 (DBC1), which unleashes SIRT1 from its inactive state and leads to an increase in its deacetylase activity. Importantly, SIRT1 ISGylation promoted lung cancer progression and limited lung cancer cell sensitivity to DNA damage-based therapeutics in vivo and in vitro models. The levels of ISG15 mRNA and protein were significantly higher in lung cancer tissues than in adjacent normal tissues. Accordingly, elevated expression of SIRT1 and ISG15 was associated with poor prognosis in lung cancer patients, a finding that could be translated for lung cancer patient stratification and disease outcome evaluation. Taken together, our findings provide a mechanistic understanding of the regulatory effect of SIRT1 ISGylation on tumor progression and therapeutic efficacy in lung cancer.

Bi-Catalyzed Trifluoromethylation of C(sp2)-H Bonds under Light.

We disclose a Bi-catalyzed C-H trifluoromethylation of (hetero)arenes using CF3SO2Cl under light irradiation. The catalytic method permits the direct functionalization of various heterocycles bearing distinct functional groups. The structural and computational studies suggest that the process occurs through an open-shell redox manifold at bismuth, comprising three unusual elementary steps for a main group element. The catalytic cycle starts with rapid oxidative addition of CF3SO2Cl to a low-valent Bi(I) catalyst, followed by a light-induced homolysis of Bi(III)-O bond to generate a trifluoromethyl radical upon extrusion of SO2, and is closed with a hydrogen-atom transfer to a Bi(II) radical intermediate.

Deoxyfluorination of 1°, 2°, and 3° Alcohols by Nonbasic O-H Activation and Lewis Acid-Catalyzed Fluoride Shuttling.

A method for deoxyfluorination of aliphatic primary, secondary, and tertiary alcohols is reported, employing a nontrigonal phosphorus triamide for base-free alcohol activation in conjunction with an organic soluble fluoride donor and a triarylborane fluoride shuttling catalyst. Mechanistic experiments are consistent with a reaction that proceeds by the collapse of an oxyphosphonium fluoroborate ion pair with fluoride transfer. The substrate scope complements existing deoxyfluorination methods and enables the preparation of homochiral secondary and tertiary alkylfluorides by stereoinversion of the substrate alcohol.

Mechanistic Studies on the Bismuth-Catalyzed Transfer Hydrogenation of Azoarenes.

Organobismuth-catalyzed transfer hydrogenation has recently been disclosed as an example of low-valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide mechanistic insights into a Bi-catalyzed transfer hydrogenation of azoarenes using p-trifluoromethylphenol (4) and pinacolborane (5) as hydrogen sources. A kinetic analysis elucidated the rate orders in all components in the catalytic reaction and determined that 1 a (2,6-bis[N-(tert-butyl)iminomethyl]phenylbismuth) is the resting state. In the transfer hydrogenation of azobenzene using 1 a and 4, an equilibrium between 1 a and 1 a ⋅ [OAr]2 (Ar=p-CF3 -C6 H4 ) is observed, and its thermodynamic parameters are established through variable-temperature NMR studies. Additionally, pKa -gated reactivity is observed, validating the proton-coupled nature of the transformation. The ensuing 1 a ⋅ [OAr]2 is crystallographically characterized, and shown to be rapidly reduced to 1 a in the presence of 5. DFT calculations indicate a rate-limiting transition state in which the initial N-H bond is formed via concerted proton transfer upon nucleophilic addition of 1 a to a hydrogen-bonded adduct of azobenzene and 4. These studies guided the discovery of a second-generation Bi catalyst, the rate-limiting transition state of which is lower in energy, leading to catalytic transfer hydrogenation at lower catalyst loadings and at cryogenic temperature.

Bismuth radical catalysis in the activation and coupling of redox-active electrophiles.

Radical cross-coupling reactions represent a revolutionary tool to make C(sp3)-C and C(sp3)-heteroatom bonds by means of transition metals and photoredox or electrochemical approaches. However, the use of main-group elements to harness this type of reactivity has been little explored. Here we show how a low-valency bismuth complex is able to undergo one-electron oxidative addition with redox-active alkyl-radical precursors, mimicking the behaviour of first-row transition metals. This reactivity paradigm for bismuth gives rise to well-defined oxidative addition complexes, which could be fully characterized in solution and in the solid state. The resulting Bi(III)-C(sp3) intermediates display divergent reactivity patterns depending on the α-substituents of the alkyl fragment. Mechanistic investigations of this reactivity led to the development of a bismuth-catalysed C(sp3)-N cross-coupling reaction that operates under mild conditions and accommodates synthetically relevant NH-heterocycles as coupling partners.

Bismuth Redox Catalysis: An Emerging Main-Group Platform for Organic Synthesis.

Bismuth has recently been shown to be able to maneuver between different oxidation states, enabling access to unique redox cycles that can be harnessed in the context of organic synthesis. Indeed, various catalytic Bi redox platforms have been discovered and revealed emerging opportunities in the field of main group redox catalysis. The goal of this perspective is to provide an overview of the synthetic methodologies that have been developed to date, which capitalize on the Bi redox cycling. Recent catalytic methods via low-valent Bi(II)/Bi(III), Bi(I)/Bi(III), and high-valent Bi(III)/Bi(V) redox couples are covered as well as their underlying mechanisms and key intermediates. In addition, we illustrate different design strategies stabilizing low-valent and high-valent bismuth species, and highlight the characteristic reactivity of bismuth complexes, compared to the lighter p-block and d-block elements. Although it is not redox catalysis in nature, we also discuss a recent example of non-Lewis acid, redox-neutral Bi(III) catalysis proceeding through catalytic organometallic steps. We close by discussing opportunities and future directions in this emerging field of catalysis. We hope that this Perspective will provide synthetic chemists with guiding principles for the future development of catalytic transformations employing bismuth.

Binocular game versus part-time patching for treatment of anisometropic amblyopia in Chinese children: a randomised clinical trial.

AIMS: To compare amblyopic-eye visual acuity (VA) and binocularity improvement of a binocular game with part-time patching in the treatment of Chinese children with anisometropic amblyopia. METHODS: 103 Chinese children aged 3-13 years with anisometropic amblyopia were recruited in a randomised clinical trial. Eligible participants were randomly assigned to the binocular, patching and combined groups. Primary outcome was amblyopic-eye VA improvement at 3 months. Secondary outcomes included reduction of suppression and change of stereoacuity. RESULTS: Of 85 completed participants, 44 (52%) were women and mean (SD) age was 5.99 (2.33) years. At 3 months, mean (95% CI) amblyopic-eye VA improved 0.18 (0.10-0.26), 0.28 (0.19-0.36) and 0.30 (0.21-0.39) logarithm of the minimum angle of resolution in the binocular, patching and combined groups, respectively. After adjusting for baseline VA, the difference was statistically significant (F=6.29, p=0.003), favouring as follows: the combined group, the patching group and the binocular group. After treatment, Titmus (x2binocular=9.75, p=0.007; x2combined=9.35, p=0.009) and dynamic stereoacuity (x2binocular=12.56, p=0.01; x2combined=12.66, p=0.01) improved only in the binocular and combined groups. Among groups, only Titmus improvement differed significantly (F=49.55, p<0.001). Changes of other types of stereoacuity and interocular suppression were similar. CONCLUSIONS: The binocular game used in this study could improve amblyopic-eye VA and binocularity in Chinese children with anisometropic amblyopia, but it was less effective than patching in amblyopic-eye VA improvement and showed no superiority in binocularity over patching. It remains unclear whether the low treatment response of this binocular game was due to limitations of the study or its low treatment effect.

Protein Quality Control in the Endoplasmic Reticulum and Cancer.

The endoplasmic reticulum (ER) is an essential compartment of the biosynthesis, folding, assembly, and trafficking of secretory and transmembrane proteins, and consequently, eukaryotic cells possess specialized machineries to ensure that the ER enables the proteins to acquire adequate folding and maturation for maintaining protein homeostasis, a process which is termed proteostasis. However, a large variety of physiological and pathological perturbations lead to the accumulation of misfolded proteins in the ER, which is referred to as ER stress. To resolve ER stress and restore proteostasis, cells have evolutionary conserved protein quality-control machineries of the ER, consisting of the unfolded protein response (UPR) of the ER, ER-associated degradation (ERAD), and autophagy. Furthermore, protein quality-control machineries of the ER play pivotal roles in the control of differentiation, progression of cell cycle, inflammation, immunity, and aging. Therefore, severe and non-resolvable ER stress is closely associated with tumor development, aggressiveness, and response to therapies for cancer. In this review, we highlight current knowledge in the molecular understanding and physiological relevance of protein quality control of the ER and discuss new insights into how protein quality control of the ER is implicated in the pathogenesis of cancer, which could contribute to therapeutic intervention in cancer.

ISG15 in cancer: Beyond ubiquitin-like protein.

ISG15, the product of interferon (IFN)-stimulated gene 15, is the first identified ubiquitin-like protein (Ubl), playing roles not only as an unconjugated form but also as a covalently conjugated form onto a target protein. ISG15 is not present in lower eukaryotes such as yeast, nematode (Caenorhabditis), or insect (Drosophila), indicating that the functions of ISG15 and ISG15 conjugation (ISGylation) are restricted to higher eukaryotes and have evolved with IFN signaling. Despite the highlighted complexity of ISG15 and ISGylation, increasing evidences have been emerging that ISG15 and ISGylation are implicated in a variety of pivotal cellular processes, involving protein translation, autophagy, exosome secretion, DNA repair, and immune modulation, which emphasizes the necessity of re-evaluation of ISG15 and ISGylation. In this review, we highlight current knowledge in the molecular understanding and physiological relevance of ISG15 and ISGylation and discuss new insights into how ISG15 is implicated in the pathogenesis of cancer, which could contribute to therapeutic intervention in cancer.

Accelerated Development of Hippocampal Neurons and Limited Adhesion of Astrocytes on Negatively Charged Surfaces.

This work examines the development of primary neurons and astrocytes on thoroughly controlled functional groups. Negatively charged surfaces presenting carboxylate (COO-) or sulfonate (SO3-) groups prove beneficial to neuronal behavior, in spite of their supposed repulsive electrostatic interactions with cellular membranes. The adhesion and survival of primary hippocampal neurons on negatively charged surfaces are comparable to or slightly better than those on positively charged (poly-d-lysine-coated) surfaces, and neuritogenesis and neurite outgrowth are accelerated on COO- and SO3- surfaces. Moreover, such favorable influences of the negatively charged surfaces are only seen in neurons but not for astrocytes. Our results indicate that the in vitro developmental behavior of primary hippocampal neurons is sophisticatedly modulated by angstrom-sized differences in chemical structure or the charge density of the surface. We believe that this work provides new implications for understanding neuron-material interfaces as well as for establishing new ways to fabricate neuro-active surfaces.

Stable Open-Shell Phosphorane Based on a Redox-Active Amidodiphenoxide Scaffold.

The synthesis and redox reactivity of pentacoordinate phosphorus compounds incorporating a redox-active ONO amidodiphenoxide scaffold [ONO = N,N-bis(3,5-di-tert-butyl-2-phenoxide)amide] are described. Dichloro- and diphenylphosphoranes, 2·Cl2 and 2·Ph2, respectively, are synthesized and crystallographically characterized. Cyclic voltammograms of 2·Cl2 show only a single irreversible oxidation (Epa = +0.83 V vs Cp2Fe0/+), while the diphenyl analogue 2·Ph2 is reversibly oxidized at lower applied potential (E1/2 = +0.47 V vs Cp2Fe0/+). Chemical oxidation of 2·Ph2 with AgBF4 produces the corresponding radical cation [2·Ph2]•+, where electron paramagnetic resonance spectroscopy and density functional theory calculations reveal that the unpaired spin density is largely ligand-based and is highly delocalized throughout the ONO framework of the paramagnetic species. The solid-state structures indicate only minor geometrical changes between the neutral 2·Ph2 and oxidized [2·Ph2]•+ species, consistent with fast self-exchange electron transfer, as observed by NMR line-broadening experiments.

Comparison of operative mortality and complications between bronchoplastic lobectomy and pneumonectomy in lung cancer patients.

Bronchoplastic lobectomy is a lung-saving procedure indicated for central tumors, for which the alternative is pneumonectomy. We compared operative mortality and complications between bronchoplastic lobectomy and pneumonectomy in lung cancer patients. From March 1993 through December 2005, 1,461 patients were surgically resected for non-small cell lung cancer, including 73 who underwent bronchoplastic lobectomy and 258 who underwent pneumonectomy. Bronchoplastic lobectomy was performed on any lesion that could be completely resected by this technique, whereas pneumonectomy was only performed on lesions that could not be removed by bronchoplastic lobectomy. Operative deaths occurred in 1 of 73 (1.4%) bronchoplastic lobectomy and 26 of 258 (10.1%) pneumonectomy patients (p=0.014). Major complications occurred in 16 of 73 (21.9%) bronchoplastic lobectomy and 58 of 258 (22.5%) pneumonectomy patients (p=1.0). Bronchoplastic lobectomy has a lower risk of operative mortality than pneumonectomy. Although the complication rates were similar, bronchoplastic lobectomy was associated with improved postoperative cardiopulmonary status and a low prevalence of fatal complications after bronchial anastomosis. These findings indicate that bronchoplastic lobectomy is a valuable alternative to pneumonectomy for anatomically appropriate patients, regardless of underlying cardiopulmonary function.