The transcription factor STAT5 catalyzes Mannich ligation reactions yielding inhibitors of leukemic cell proliferation

Biological processes are often regulated by signal transduction pathway via transcription factor through protein-protein interactions (PPIs). Aberrant activation of transcription factor deregulates the cell signaling pathway which contributes to disease progression. Cancer is well characterized as a result of over activation of transcription factor and/or loss of an essential protein-protein interaction. Therefore, transcription factor have become attractive molecular target for drug development. Protein-templated fragment ligations have been established as a powerful method for the assembly and detection of optimized protein ligands. Initially developed for reversible ligations, the method has been expanded to irreversible reactions enabling the formation of super-additive fragment combinations. In this thesis, protein-induced Mannich ligations are introduced and discovered as a biocatalytic reaction furnishing inhibitors of the transcription factor STAT5. STAT5 protein was employed to catalyze multicomponent reactions of a phosphate mimetic, formaldehyde, and 1H-tetrazoles yielding protein ligands with greatly increased binding affinity and ligand efficiency. Reactions are induced under physiological conditions selectively by native STAT5 but not by other proteins. Formation of ligation products and (auto-) inhibition of the reaction are quantified and the mechanism is investigated. Inhibitors assembled by STAT5 were further validated using functional biochemical assay and were proven to block specifically the phosphorylation of this protein in a cellular model of acute myeloid leukemia (AML), DNA-binding of STAT5 dimers, expression of downstream targets of the transcription factor, and the proliferation of cancer cells in mice. In addition, STAT5 inhibitors also exert strong synergistic effect with tyrosine kinase inhibitor, PKC412 in targeting leukemic cells. Throughout our effort in establishing highly selective STAT5 inhibitor, a first class of inhibitors that assembled through protein induced Mannich ligation reported to date have been successfully identified. STAT5 assembled inhibitors have proven to exhibit favorable potency and selectivity profile against STAT5 and possess the potential to become candidate for combination therapy with tyrosine kinase inhibitor for pre-clinical trials as STAT5 targeted therapeutic. Last but not least, these small molecules STAT5 inhibitors well served as a research tool to study the effect of knocking down of STAT5 function at the protein level on cancer prognosis and progression.Biologische Prozesse werden häufig über Signaltransduktionswege durch Transkriptionsfaktoren gesteuert und werden durch Protein-Protein-Interaktion (PPIs) vermittelt. Die abweichende Aktivierung eines Transkriptionsfaktors verändert den zellulären Signalweg, was zur Entwicklung oder zum Fortschreiten von Krankheiten beitragen kann. Krebs ist gut charakterisiert als das Ergebnis einer Überaktivierung von Transkriptionsfaktoren und/oder des Verlustes von essentiellen Protein-Protein-Interaktionen. Daher sind Transkriptionsfaktoren ein attraktives molekulares Ziel für die Arzneimittelentwicklung. Protein-templierte Fragment-Ligationen wurden als leistungsfähiges Verfahren zur Gewinnung und zur Erkennung von optimierten Protein-Liganden eingeführt. Ursprünglich entwickelt für reversible Ligationen wurde die Methode auf irreversible Reaktionen ausgeweitet und ermöglicht die Bildung von super-additiven Fragmentkombinationen. In dieser Arbeit werden protein-induzierte Mannich-Ligationen als eine biokatalytische Reaktion entdeckt, die Inhibitoren für den Transkriptionsfaktor STAT5 liefern. STAT5-Protein katalysiert Multikomponenten-Reaktionen eines Phosphat-Mimetikums, von Formaldehyd und von 1H-Tetrazolen, die Proteinliganden mit stark erhöhter Bindungsaffinität und Ligandeneffizienz liefern. Reaktionen werden unter physiologischen Bedingungen selektiv durch natives STAT5, aber nicht durch andere Proteine ausgelöst. Die Bildung von Ligationsprodukten und die (Auto-)Inhibition der Reaktion werden gemessen und der Mechanismus wird erforscht. Durch STAT5 gebildeten Inhibitoren werden weiter in funktionellen biochemischen Assays validiert und es wird gezeigt, dass sie spezifisch die Phosphorylierung dieses Proteins in einem zellulären Modell der akuten myeloischen Leukämie (AML), die DNA-Bindung von STAT5-Dimern, die Expression von Zielproteinen des Transkriptionsfaktors und die Proliferation von Krebszellen in Mäusen blockieren. Zusätzlich haben STAT5-Inhibitoren zusammen mit dem Tyrosinkinase-Inhibitor PKC412 eine starke synergistische Wirkung auf Leukämiezellen. Wir haben die erste bisher bekannte Klasse von Inhibitoren identifiziert, die durch eine Protein-induzierte Mannich-Ligation gebildet wurden. Die durch STAT5 entstandenen Inhibitoren zeigen günstige Wirkungen und ein vorteilhaftes Selektivitätsprofil gegenüber STAT5 und besitzen das Potential, Kandidaten für eine Kombinationstherapie mit Tyrosinkinase-Inhibitoren für vorklinische Versuche als gezielte STAT5-Therapien zu werden. Zu guter Letzt dienten diese kleinen STAT5 Inhibitor-Moleküle als geeignete Forschungswerkzeuge, um die Effekte der Ausschaltung von STAT5-Funktionen auf die Prognose und den Verlauf von Krebserkrankungen zu untersuchen

The structural and functional studies of the non-stereospecific α-haloacid dehalogenase (DehE) from rhizobium sp. RC1

Environmental pollution caused by the abundance of xenobi otic compounds in nature. For instance, synthetically halogenated compounds released from chemical industry we re proven harmful to our health and environment. However, α-haloacid dehalogenases could catalysed the removal of halides from organic haloalkanoic acids and of interest for bioremediation. This study presents the first structural conformations and important residues of the non-stereospecific α-haloacid dehalogenase, DehE from Rhizobium sp. RC1. The enzyme was modeled using ‘in silico’technique and crystal structure of DehI from Pseudomonas putida PP3 was used as a template since both of them gets high similiarity to each other. DehE consis ts of only helices motif and depicted active site showed that the binding orientiations of both D- and L-2-chlor opropionic acid by using substrate-docking analysis shared similar key binding residues among non-stereo specific α -haloacid dehalogenases. Twelve residues lining the active site has identified and some of them were verified using site-directed mutagenesis tests. Each residues was affected after mutation and Asp189 was proven to be as a catalytic residue for nucleophilic attack mechansim when its mutation resulted in total loss of activity. Three binding residues, Trp34, Phe37 and Ser188 were responsible for substrate recognition due to their mutati on had diminish activity of the enzyme to below 20%. These details will promote more protein engineering studies to α haloacid dehalogenases for future bioremediation and industrial applications

Survival and hepatitis status among Asian Americans with hepatocellular carcinoma treated without liver transplantation

<p>Abstract</p> <p>Background</p> <p>Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) are established causes of HCC. HCC patients are often diagnosed late and receive palliative therapies, however, the survival of Asian American patients with HCC treated without transplantation has not been well studied. We reviewed our institution's experience to determine predictors and rates of survival in Asian American HCC patients treated without transplantation.</p> <p>Methods</p> <p>We identified Asian American patients with HCC referred to M. D. Anderson Cancer Center. Patients were tested for HBV and HCV. Survival curves were generated by Kaplan-Meier method. Multivariate Cox proportional hazards regression was used to test the relationship between prognostic factors and survival.</p> <p>Results</p> <p>Of 82 Asian American HCC patients, most had advanced disease (65%) and received treatment (68%); however, only 11% had surgical resection. 94% had positive anti-HBc and 61% had positive HBsAg. 20% had positive anti-HCV. There were no significant changes in the rates of HBV and HCV over time. Male gender, high alpha-fetoprotein levels, and stage IV disease were associated with shorter survival Overall median survival was 9.2 months (95% CI 6.5–11.9), and the survival of HCV and HBV patients was not statistically different.</p> <p>Conclusion</p> <p>The survival rate of Asian American patients with advanced HCC, for whom transplantation was not available, was low. Timely hepatitis screening and interventions by primary care physicians may be the most logical solution to reduce the burden of hepatitis-associated HCC among Asian Americans.</p

cis-Expression QTL Analysis of Established Colorectal Cancer Risk Variants in Colon Tumors and Adjacent Normal Tissue

Genome-wide association studies (GWAS) have identified 19 risk variants associated with colorectal cancer. As most of these risk variants reside outside the coding regions of genes, we conducted cis-expression quantitative trait loci (cis-eQTL) analyses to investigate possible regulatory functions on the expression of neighboring genes. Forty microsatellite stable and CpG island methylator phenotype-negative colorectal tumors and paired adjacent normal colon tissues were used for genome-wide SNP and gene expression profiling. We found that three risk variants (rs10795668, rs4444235 and rs9929218, using near perfect proxies rs706771, rs11623717 and rs2059252, respectively) were significantly associated (FDR q-value ≤0.05) with expression levels of nearby genes (<2 Mb up- or down-stream). We observed an association between the low colorectal cancer risk allele (A) for rs10795668 at 10p14 and increased expression of ATP5C1 (q = 0.024) and between the colorectal cancer high risk allele (C) for rs4444235 at 14q22.2 and increased expression of DLGAP5 (q = 0.041), both in tumor samples. The colorectal cancer low risk allele (A) for rs9929218 at 16q22.1 was associated with a significant decrease in expression of both NOL3 (q = 0.017) and DDX28 (q = 0.046) in the adjacent normal colon tissue samples. Of the four genes, DLGAP5 and NOL3 have been previously reported to play a role in colon carcinogenesis and ATP5C1 and DDX28 are mitochondrial proteins involved in cellular metabolism and division, respectively. The combination of GWAS findings, prior functional studies, and the cis-eQTL analyses described here suggest putative functional activities for three of the colorectal cancer GWAS identified risk loci as regulating the expression of neighboring genes

Disparities and risks of sexually transmissible infections among men who have sex with men in China: a meta-analysis and data synthesis.

BACKGROUND: Sexually transmitted infections (STIs), including Hepatitis B and C virus, are emerging public health risks in China, especially among men who have sex with men (MSM). This study aims to assess the magnitude and risks of STIs among Chinese MSM. METHODS: Chinese and English peer-reviewed articles were searched in five electronic databases from January 2000 to February 2013. Pooled prevalence estimates for each STI infection were calculated using meta-analysis. Infection risks of STIs in MSM, HIV-positive MSM and male sex workers (MSW) were obtained. This review followed the PRISMA guidelines and was registered in PROSPERO. RESULTS: Eighty-eight articles (11 in English and 77 in Chinese) investigating 35,203 MSM in 28 provinces were included in this review. The prevalence levels of STIs among MSM were 6.3% (95% CI: 3.5-11.0%) for chlamydia, 1.5% (0.7-2.9%) for genital wart, 1.9% (1.3-2.7%) for gonorrhoea, 8.9% (7.8-10.2%) for hepatitis B (HBV), 1.2% (1.0-1.6%) for hepatitis C (HCV), 66.3% (57.4-74.1%) for human papillomavirus (HPV), 10.6% (6.2-17.6%) for herpes simplex virus (HSV-2) and 4.3% (3.2-5.8%) for Ureaplasma urealyticum. HIV-positive MSM have consistently higher odds of all these infections than the broader MSM population. As a subgroup of MSM, MSW were 2.5 (1.4-4.7), 5.7 (2.7-12.3), and 2.2 (1.4-3.7) times more likely to be infected with chlamydia, gonorrhoea and HCV than the broader MSM population, respectively. CONCLUSION: Prevalence levels of STIs among MSW were significantly higher than the broader MSM population. Co-infection of HIV and STIs were prevalent among Chinese MSM. Integration of HIV and STIs healthcare and surveillance systems is essential in providing effective HIV/STIs preventive measures and treatments. TRIAL REGISTRATION: PROSPERO NO: CRD42013003721

The Use of Nanoscale Visible Light-Responsive Photocatalyst TiO2-Pt for the Elimination of Soil-Borne Pathogens

Exposure to the soil-borne pathogens Burkholderia pseudomallei and Burkholderia cenocepacia can lead to severe infections and even mortality. These pathogens exhibit a high resistance to antibiotic treatments. In addition, no licensed vaccine is currently available. A nanoscale platinum-containing titania photocatalyst (TiO2-Pt) has been shown to have a superior visible light-responsive photocatalytic ability to degrade chemical contaminants like nitrogen oxides. The antibacterial activity of the catalyst and its potential use in soil pathogen control were evaluated. Using the plating method, we found that TiO2-Pt exerts superior antibacterial performance against Escherichia coli compared to other commercially available and laboratory prepared ultraviolet/visible light-responsive titania photocatalysts. TiO2-Pt-mediated photocatalysis also affectively eliminates the soil-borne bacteria B. pseudomallei and B. cenocepacia. An air pouch infection mouse model further revealed that TiO2-Pt-mediated photocatalysis could reduce the pathogenicity of both strains of bacteria. Unexpectedly, water containing up to 10% w/v dissolved soil particles did not reduce the antibacterial potency of TiO2-Pt, suggesting that the TiO2-Pt photocatalyst is suitable for use in soil-contaminated environments. The TiO2-Pt photocatalyst exerted superior antibacterial activity against a broad spectrum of human pathogens, including B. pseudomallei and B. cenocepacia. Soil particles (<10% w/v) did not significantly reduce the antibacterial activity of TiO2-Pt in water. These findings suggest that the TiO2-Pt photocatalyst may have potential applications in the development of bactericides for soil-borne pathogens

The epidemic of sexually transmitted infections in China: implications for control and future perspectives

China has experienced an increasing epidemic of sexually transmitted infections (STIs), including HIV. High risk groups likely to be infected include female sex workers (FSWs) and their clients, men who have sex with men (MSM), drug users and migrant workers. Prevention can be achieved through education of the population, condom promotion, early detection of symptomatic and asymptomatic people, and effective diagnosis and treatment of these patients and their partners. This article aims to describe the profile of the epidemic in high-risk groups in China as well as to detail the contributing factors and the implications for control. Programmes for the control of STIs should be immediate priorities in China, and primary and secondary prevention strategies are vital to this process

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT