Development of a rapid, simple, and sensitive point-of-care technology platform utilizing ternary NanoLuc

Point-of-care tests are highly valuable in providing fast results for medical decisions for greater flexibility in patient care. Many diagnostic tests, such as ELISAs, that are commonly used within clinical laboratory settings require trained technicians, laborious workflows, and complex instrumentation hindering their translation into point-of-care applications. Herein, we demonstrate the use of a homogeneous, bioluminescent-based, split reporter platform that enables a simple, sensitive, and rapid method for analyte detection in clinical samples. We developed this point-of-care application using an optimized ternary, split-NanoLuc luciferase reporter system that consists of two small reporter peptides added as appendages to analyte-specific affinity reagents. A bright, stable bioluminescent signal is generated as the affinity reagents bind to the analyte, allowing for proximity-induced complementation between the two reporter peptides and the polypeptide protein, in addition to the furimazine substrate. Through lyophilization of the stabilized reporter system with the formulated substrate, we demonstrate a shelf-stable, all-in-one, add-and-read analyte-detection system for use in complex sample matrices at the point-of-care. We highlight the modularity of this platform using two distinct SARS-CoV-2 model systems: SARS-CoV-2 N-antigen detection for active infections and anti-SARS-CoV-2 antibodies for immunity status detection using chemically conjugated or genetically fused affinity reagents, respectively. This technology provides a simple and standardized method to develop rapid, robust, and sensitive analyte-detection assays with flexible assay formatting making this an ideal platform for research, clinical laboratory, as well as point-of-care applications utilizing a simple handheld luminometer.

Simple, Rapid Chemical Labeling and Screening of Antibodies with Luminescent Peptides

Sensitive and selective detection assays are essential for the accurate measurement of analytes in both clinical and research laboratories. Immunoassays that rely on nonoverlapping antibodies directed against the same target analyte (e.g., sandwich enzyme-linked immunosorbent assays (ELISAs)) are commonly used molecular detection technologies. Use of split enzyme reporters has simplified the workflow for these traditionally complex assays. However, identifying functional antibody pairs for a given target analyte can be cumbersome, as it generally involves generating and screening panels of antibodies conjugated to reporters. Accordingly, we sought a faster and easier reporter conjugation strategy to streamline antibody screening. We describe here the development of such a method that is based on an optimized ternary NanoLuc luciferase. This bioluminescence complementation system is comprised of a reagent-based thermally stable polypeptide (LgTrip) and two small peptide tags (β9 and β10) with lysine-reactive handles for direct conjugation onto antibodies. These reagents enable fast, single-step, wash-free antibody labeling and sensitive functional screening. Simplicity, speed, and utility of the one-pot labeling technology are demonstrated in screening antibody pairs for the analyte interleukin-4. The screen resulted in the rapid development of a sensitive homogeneous immunoassay for this clinically relevant cytokine.

An Integrated Approach toward NanoBRET Tracers for Analysis of GPCR Ligand Engagement

Gaining insight into the pharmacology of ligand engagement with G-protein coupled receptors (GPCRs) under biologically relevant conditions is vital to both drug discovery and basic research. NanoLuc-based bioluminescence resonance energy transfer (NanoBRET) monitoring competitive binding between fluorescent tracers and unmodified test compounds has emerged as a robust and sensitive method to quantify ligand engagement with specific GPCRs genetically fused to NanoLuc luciferase or the luminogenic HiBiT peptide. However, development of fluorescent tracers is often challenging and remains the principal bottleneck for this approach. One way to alleviate the burden of developing a specific tracer for each receptor is using promiscuous tracers, which is made possible by the intrinsic specificity of BRET. Here, we devised an integrated tracer discovery workflow that couples machine learning-guided in silico screening for scaffolds displaying promiscuous binding to GPCRs with a blend of synthetic strategies to rapidly generate multiple tracer candidates. Subsequently, these candidates were evaluated for binding in a NanoBRET ligand-engagement screen across a library of HiBiT-tagged GPCRs. Employing this workflow, we generated several promiscuous fluorescent tracers that can effectively engage multiple GPCRs, demonstrating the efficiency of this approach. We believe that this workflow has the potential to accelerate discovery of NanoBRET fluorescent tracers for GPCRs and other target classes.

Toward a Point-of-Need Bioluminescence-Based Immunoassay Utilizing a Complete Shelf-Stable Reagent

Enzyme-linked immunosorbent assays (ELISAs) are used extensively for the detection and quantification of biomolecules in clinical diagnostics as well as in basic research. Although broadly used, the inherent complexities of ELISAs preclude their utility for straightforward point-of-need testing, where speed and simplicity are essential. With this in mind, we developed a bioluminescence-based immunoassay format that provides a sensitive and simple method for detecting biomolecules in clinical samples. We utilized a ternary, split-NanoLuc luciferase complementation reporter consisting of two small peptides (11mer, 13mer) and a 17 kDa polypeptide combined with a luminogenic substrate to create a complete, shelf-stable add-and-read assay detection reagent. Directed evolution was used to optimize reporter constituent sequences to impart chemical and thermal stability, as well as solubility, while formulation optimization was applied to stabilize an all-in-one reagent that can be reconstituted in aqueous buffers or sample matrices. The result of these efforts is a robust, first-generation bioluminescence-based homogenous immunoassay reporter platform where all assay components can be configured into a stable lyophilized cake, supporting homogeneous, rapid, and sensitive one-step biomolecule quantification in complex human samples. This technology represents a promising alternative immunoassay format with significant potential to bring critical diagnostic molecular detection testing closer to the point-of-need.

Streamlined Target Deconvolution Approach Utilizing a Single Photoreactive Chloroalkane Capture Tag

Identification of physiologically relevant targets for lead compounds emerging from drug discovery screens is often the rate-limiting step toward understanding their mechanism of action and potential for undesired off-target effects. To this end, we developed a streamlined chemical proteomic approach utilizing a single, photoreactive cleavable chloroalkane capture tag, which upon attachment to bioactive compounds facilitates selective isolation of their respective cellular targets for subsequent identification by mass spectrometry. When properly positioned, the tag does not significantly affect compound potency and membrane permeability, allowing for binding interactions with the tethered compound (probe) to be established within intact cells under physiological conditions. Subsequent UV-induced covalent photo-cross-linking "freezes" the interactions between the probe and its cellular targets and prevents their dissociation upon cell lysis. Targets cross-linked to the capture tag are then efficiently enriched through covalent capture onto HaloTag coated beads and subsequent selective chemical release from the solid support. The tag's built-in capability for selective enrichment eliminates the need for ligation of a capture tag, thereby simplifying the workflow and reducing variability introduced through additional operational steps. At the same time, the capacity for adequate cross-linking without structural optimization permits modular assembly of photoreactive chloroalkane probes, which reduces the burden of customized chemistry. Using three model compounds, we demonstrate the capability of this approach to identify known and novel cellular targets, including those with low affinity and/or low abundance as well as membrane targets with several transmembrane domains.

Equilibrium and Kinetic Measurements of Ligand Binding to HiBiT-tagged GPCRs on the Surface of Living Cells

G-protein coupled receptors (GPCRs) remain at the forefront of drug discovery efforts. Detailed assessment of features contributing to GPCR ligand engagement in a physiologically relevant environment is imperative to the development of new therapeutics with improved efficacy. Traditionally, binding properties such as affinity and kinetics were obtained using biochemical radioligand binding assays. More recently, the high specificity of resonance energy transfer has been leveraged toward the development of homogeneous cell-based proximity assays with capacity for real-time kinetic measurements. This suite of ligand binding protocols couples the specificity of bioluminescent resonance energy transfer (BRET) with the sensitivity afforded by the luminescent HiBiT peptide. The BRET format is used to quantify dynamic interactions between ligands and their cognate HiBiT-tagged GPCRs through competitive binding with fluorescent Tracers. At the same time, high affinity complementation of HiBiT with the cell impermeable LgBiT limits the bright bioluminescence donor signal to the cell surface and eliminates luminescence background from unoccupied receptors present in intracellular compartments.

Novel NanoLuc substrates enable bright two-population bioluminescence imaging in animals

Sensitive detection of two biological events in vivo has long been a goal in bioluminescence imaging. Antares, a fusion of the luciferase NanoLuc to the orange fluorescent protein CyOFP, has emerged as a bright bioluminescent reporter with orthogonal substrate specificity to firefly luciferase (FLuc) and its derivatives such as AkaLuc. However, the brightness of Antares in mice is limited by the poor solubility and bioavailability of the NanoLuc substrate furimazine. Here, we report a new substrate, hydrofurimazine, whose enhanced aqueous solubility allows delivery of higher doses to mice. In the liver, Antares with hydrofurimazine exhibited similar brightness to AkaLuc with its substrate AkaLumine. Further chemical exploration generated a second substrate, fluorofurimazine, with even higher brightness in vivo. We used Antares with fluorofurimazine to track tumor size and AkaLuc with AkaLumine to visualize CAR-T cells within the same mice, demonstrating the ability to perform two-population imaging with these two luciferase systems.

Health Care Executive Perceptions of Hiring and Retention Practices of People With Disabilities: Results From Executive Focus Groups

The supply-side approach to providing services without taking into account employer practices has not been effective in achieving meaningful, competitive, and integrated employment outcomes for people with disabilities. This focus neglects the fact that disability and employment is a two-way process with businesses being accountable for such demand-side factors as establishing better hiring, retention, and advancement practices. To initiate the identification of effective employer practices, this article shares the results of two executive focus groups that were conducted in a large health care organization, across four individual hospitals, with a documented success rate of hiring and retaining people with disabilities (PWDs). The purpose of the focus groups was to explore executive perceptions of their organization’s success at integrating PWDs throughout their work force. Results are explored through five identified themes: (a) organizational mission guided decision-making concerning the employment of PWDs, (b) executives living the mission through their daily inclusive behaviors led to employing PWDs, (c) organizational values were important to employing PWDs, (d) the organization benefited from employment of PWDs, and (e) employing PWDs benefited organization staff and the surrounding community. The results of these executive focus groups provide an initial glimpse into the culture and practices of a highly effective organization.

The luminescent HiBiT peptide enables selective quantitation of G protein-coupled receptor ligand engagement and internalization in living cells

G protein-coupled receptors (GPCRs) are prominent targets to new therapeutics for a range of diseases. Comprehensive assessments of their cellular interactions with bioactive compounds, particularly in a kinetic format, are imperative to the development of drugs with improved efficacy. Hence, we developed complementary cellular assays that enable equilibrium and real-time analyses of GPCR ligand engagement and consequent activation, measured as receptor internalization. These assays utilize GPCRs genetically fused to an N-terminal HiBiT peptide (1.3 kDa), which produces bright luminescence upon high-affinity complementation with LgBiT, an 18-kDa subunit derived from NanoLuc. The cell impermeability of LgBiT limits signal detection to the cell surface and enables measurements of ligand-induced internalization through changes in cell-surface receptor density. In addition, bioluminescent resonance energy transfer is used to quantify dynamic interactions between ligands and their cognate HiBiT-tagged GPCRs through competitive binding with fluorescent tracers. The sensitivity and dynamic range of these assays benefit from the specificity of bioluminescent resonance energy transfer and the high signal intensity of HiBiT/LgBiT without background luminescence from receptors present in intracellular compartments. These features allow analyses of challenging interactions having low selectivity or affinity and enable studies using endogenously tagged receptors. Using the β-adrenergic receptor family as a model, we demonstrate the versatility of these assays by utilizing the same HiBiT construct in analyses of multiple aspects of GPCR pharmacology. We anticipate that this combination of target engagement and proximal functional readout will prove useful to the study of other GPCR families and the development of new therapeutics.

Utilizing a Simple Method for Stoichiometric Protein Labeling to Quantify Antibody Blockade

Ligand binding assays routinely employ fluorescently-labeled protein ligands to quantify the extent of binding. These ligands are commonly generated through chemical modification of accessible lysine residues, which often results in heterogeneous populations exhibiting variable binding properties. This could be remedied by quantitative, site-specific labeling. Recently, we reported on a single-step method integrating recombinant protein purification with 2-cyanobenzothiazole (CBT) condensation for labeling a proteolytically exposed N-terminal cysteine. Here, using three growth factors, we show that unlike random lysine labeling, this site-specific approach yielded homogeneous populations of growth factors that were quantitatively labeled at their N-termini and retained their binding characteristics. We demonstrate the utility of this labeling method through the development of a novel assay that quantifies the capacity of antibodies to block receptor-ligand interactions (i.e. antibody blockade). The assay uses bioluminescence resonance energy transfer (BRET) to detect binding of CBT-labeled growth factors to their cognate receptors genetically fused to NanoLuc luciferase. The ability of antibodies to block these interactions is quantified through decrease in BRET. Using several antibodies, we show that the assay provides reliable quantification of antibody blockade in a cellular context. As demonstrated here, this simple method for generating uniformly-labeled proteins has potential to promote more accurate and robust ligand binding assays.

CRISPR-Mediated Tagging of Endogenous Proteins with a Luminescent Peptide

Intracellular signaling pathways are mediated by changes in protein abundance and post-translational modifications. A common approach for investigating signaling mechanisms and the effects induced by synthetic compounds is through overexpression of recombinant reporter genes. Genome editing with CRISPR/Cas9 offers a means to better preserve native biology by appending reporters directly onto the endogenous genes. An optimal reporter for this purpose would be small to negligibly influence intracellular processes, be readily linked to the endogenous genes with minimal experimental effort, and be sensitive enough to detect low expressing proteins. HiBiT is a 1.3 kDa peptide (11 amino acids) capable of producing bright and quantitative luminescence through high affinity complementation (K_D = 700 pM) with an 18 kDa subunit derived from NanoLuc (LgBiT). Using CRISPR/Cas9, we demonstrate that HiBiT can be rapidly and efficiently integrated into the genome to serve as a reporter tag for endogenous proteins. Without requiring clonal isolation of the edited cells, we were able to quantify changes in abundance of the hypoxia inducible factor 1A (HIF1α) and several of its downstream transcriptional targets in response to various stimuli. In combination with fluorescent antibodies, we further used HiBiT to directly correlate HIF1α levels with the hydroxyproline modification that mediates its degradation. These results demonstrate the ability to efficiently tag endogenous proteins with a small luminescent peptide, allowing sensitive quantitation of the response dynamics in their regulated expression and covalent modifications.

Abstract 4296: A real-time annexin V method for monitoring programmed cell death

Efficacious and durable anti-cancer responses are driven by both the selective death of malignant cells and the induction of immunostimulatory activities. Limited but promising clinical evidence suggests that provocation of an unknown balance of inflammatory- and non-inflammatory cell death may be key for orchestrating these positive outcomes. Therefore, identifying and characterizing new clinically useful small molecules and biologic inducers (or combinations thereof) which promote a spectrum of programmed cell death in in vitro screening environments remains critically important. Unfortunately, current screening methods are either insufficiently robust, cost- or resource-prohibitive, or provide no means for initial characterization of the kinetics of programmed cell death. To address this unmet need, we developed a real-time, live cell assay method that utilizes a fully homogeneous, bioluminescent annexin V reagent. The method does not require laborious washing and sample preparation steps associated with traditional annexin methods and is fully compatible with plate-based multimodal signal detection systems. The system contains two annexin proteins which have been engineered to contain separate and distinct complementing domains of a binary luciferase. Additionally, the system contains a novel time-released luciferase substrate and a cell impermeable, fluorogenic DNA dye for monitoring necrosis. Because the annexin-luciferase fusion pairs have only modest affinity for each other, luminescence remains low until phosphatidylserine exposure, a hallmark of the programmed cell death phenotype, brings annexin monomers into close proximity facilitating complementation of the luciferase sensor. The assay reagent can be applied at dosing for real-time measurement of the dose-dependency and magnitude of programmed cell death progression. This work describes our efforts to characterize and validate the performance of the bioluminescent annexin assay using relevant cell death induction models. First, the assay was shown to be functionally concordant with a flow cytometry annexin method in a dose-response model with bortezomib at exposure periods known to produce both early and late-apoptosis (with necrosis) phenotypes. Next, we assessed the performance of the assay using a limited training set of small molecule and biologic inducers of programmed cell death that utilize different mechanisms of action (i.e., apoptosis and necroptosis) and by using a number of diverse but representative cancer cell lines. We conclude that the bioluminescent annexin method provides a new kinetic approach to efficient and effective detection of programmed cell death mechanisms in real time in a convenient homogeneous format.

Citation Format: Kevin Kupcho, Andrew Niles, John Shultz, Jamison Grailer, Wenhui Zhou, Robin Hurst, Jim Hartnett, Terry Riss, Dan Lazar, James Cali. A real-time annexin V method for monitoring programmed cell death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4296. doi:10.1158/1538-7445.AM2017-4296

A reference genome for Nicotiana tabacum enables map-based cloning of homeologous loci implicated in nitrogen utilization efficiency

BACKGROUND

Tobacco (Nicotiana tabacum) is an important plant model system that has played a key role in the early development of molecular plant biology. The tobacco genome is large and its characterisation challenging because it is an allotetraploid, likely arising from hybridisation between diploid N. sylvestris and N. tomentosiformis ancestors. A draft assembly was recently published for N. tabacum, but because of the aforementioned genome complexities it was of limited utility due to a high level of fragmentation.

RESULTS

Here we report an improved tobacco genome assembly, which, aided by the application of optical mapping, achieves an N50 size of 2.17 Mb and enables anchoring of 64% of the genome to pseudomolecules; a significant increase from the previous value of 19%. We use this assembly to identify two homeologous genes that explain the differentiation of the burley tobacco market class, with potential for greater understanding of Nitrogen Utilization Efficiency and Nitrogen Use Efficiency in plants; an important trait for future sustainability of agricultural production.

CONCLUSIONS

Development of an improved genome assembly for N. tabacum enables what we believe to be the first successful map-based gene discovery for the species, and demonstrates the value of an improved assembly for future research in this model and commercially-important species.

Improved Deconvolution of Protein Targets for Bioactive Compounds Using a Palladium Cleavable Chloroalkane Capture Tag

The benefits provided by phenotypic screening of compound libraries are often countered by difficulties in identifying the underlying cellular targets. We recently described a new approach utilizing a chloroalkane capture tag, which can be chemically attached to bioactive compounds to facilitate the isolation of their respective targets for subsequent identification by mass spectrometry. The tag minimally affects compound potency and membrane permeability, enabling target engagement inside cells. Effective enrichment of these targets is achieved through selectivity in both their rapid capture onto immobilized HaloTag and their subsequent release by competitive elution. Here, we describe a significant improvement to this method where selective elution was achieved through palladium-catalyzed cleavage of an allyl-carbamate linkage incorporated into the chloroalkane capture tag. Selective tag cleavage provided robust release of captured targets exhibiting different modes of binding to the bioactive compound, including prolonged residence time and covalent interactions. Using the kinase inhibitors ibrutinib and BIRB796 as model compounds, we demonstrated the capability of this new method to identify both expected targets and "off-targets" exhibiting a range of binding affinities, cellular abundances, and binding characteristics.

Abstract 3505: A bioluminescent, homogeneous annexin V microplate-based method for assessment of apoptosis

The selective elimination of malignant cells via the apoptotic process continues to be the cornerstone of modern anti-cancer therapy regimens. Therefore, in vitro screening approaches aimed at identifying clinically useful apoptosis inducers remain critically important. Recently, phenotypic screening methods have enjoyed a resurgence due to more biologically complex and relevant cell models as well as advances in chemical proteomics which have allowed for more successful target identification. As a consequence, novel probes and tools with enabling attributes are required to fully realize this discovery potential. In an effort to address this unmet need, we have developed a bioluminescent and homogeneous annexin V binding assay for the assessment of apoptosis. Unlike traditional fluorescent annexin V methodology, the “no-wash” reagent employed in this new assay utilizes binary components of a novel luciferase separately fused to annexin V. The annexin V-luciferase subunit fusion pairs have low intrinsic affinity for each other and thus produce no or low luminescence until phosphatidylserine (PtdSer) exposure drives annexin-fusion pair oligimerization. Ultimately, this protein:protein interaction on or near the cell surface reconstitutes full luciferase activity causing an increase in luminescence in the presence of a luciferase substrate. A separate, pro-fluorescent, multiplexed component of the reagent further delineates differences in annexin positivity based on maintenance or loss of membrane integrity corresponding to apoptosis or necrosis, respectively. We validated this method using a panel of diverse cancer cell lines (U2-OS, DLD-1, HeLa, Jurkat, K562, A549, and PC-3), representing both attachment-dependent and -independent morphologies after dose-dependent challenge with intrinsic (bortezomib, panobinostat, staurosporine, and paclitaxel) and extrinsic (rhTRAIL) inducers of apoptosis as well as agents known to produce primary necrosis (ionomycin and digitonin). Caspase activation data was also collected in parallel plates at endpoint as a well-validated and sensitive orthogonal comparator. The bioluminescent annexin V method proved sufficiently robust in 384 well microplate formats to routinely produce Z’ > 0.7 and rank-order potencies in good agreement with caspase activation values. In addition to this microplate functionality, the reagent allowed for sensitive, facile imaging of apoptotic induction in living cells using different imaging platforms. Taken together, the method and reagent should provide unparalleled flexibility with regard to live cell apoptosis detection in both conventional microplate and high content-like imaging formats and advance the pace of new chemical entity discovery.

Citation Format: Kevin Kupcho, John Shultz, Andrew Niles, Wenhui Zhou, Robin Hurst, Jim Hartnett, Thomas Machleidt, Terry Riss, Dan Lazar, Jim Cali. A bioluminescent, homogeneous annexin V microplate-based method for assessment of apoptosis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3505.

Deciphering the Cellular Targets of Bioactive Compounds Using a Chloroalkane Capture Tag

Phenotypic screening of compound libraries is a significant trend in drug discovery, yet success can be hindered by difficulties in identifying the underlying cellular targets. Current approaches rely on tethering bioactive compounds to a capture tag or surface to allow selective enrichment of interacting proteins for subsequent identification by mass spectrometry. Such methods are often constrained by ineffective capture of low affinity and low abundance targets. In addition, these methods are often not compatible with living cells and therefore cannot be used to verify the pharmacological activity of the tethered compounds. We have developed a novel chloroalkane capture tag that minimally affects compound potency in cultured cells, allowing binding interactions with the targets to occur under conditions relevant to the desired cellular phenotype. Subsequent isolation of the interacting targets is achieved through rapid lysis and capture onto immobilized HaloTag protein. Exchanging the chloroalkane tag for a fluorophore, the putative targets identified by mass spectrometry can be verified for direct binding to the compound through resonance energy transfer. Using the interaction between histone deacetylases (HDACs) and the inhibitor, Vorinostat (SAHA), as a model system, we were able to identify and verify all the known HDAC targets of SAHA as well as two previously undescribed targets, ADO and CPPED1. The discovery of ADO as a target may provide mechanistic insight into a reported connection between SAHA and Huntington's disease.

Integration of copy number and transcriptomics provides risk stratification in prostate cancer: A discovery and validation cohort study

BACKGROUND

Understanding the heterogeneous genotypes and phenotypes of prostate cancer is fundamental to improving the way we treat this disease. As yet, there are no validated descriptions of prostate cancer subgroups derived from integrated genomics linked with clinical outcome.

METHODS

In a study of 482 tumour, benign and germline samples from 259 men with primary prostate cancer, we used integrative analysis of copy number alterations (CNA) and array transcriptomics to identify genomic loci that affect expression levels of mRNA in an expression quantitative trait loci (eQTL) approach, to stratify patients into subgroups that we then associated with future clinical behaviour, and compared with either CNA or transcriptomics alone.

FINDINGS

We identified five separate patient subgroups with distinct genomic alterations and expression profiles based on 100 discriminating genes in our separate discovery and validation sets of 125 and 103 men. These subgroups were able to consistently predict biochemical relapse (p = 0.0017 and p = 0.016 respectively) and were further validated in a third cohort with long-term follow-up (p = 0.027). We show the relative contributions of gene expression and copy number data on phenotype, and demonstrate the improved power gained from integrative analyses. We confirm alterations in six genes previously associated with prostate cancer (MAP3K7, MELK, RCBTB2, ELAC2, TPD52, ZBTB4), and also identify 94 genes not previously linked to prostate cancer progression that would not have been detected using either transcript or copy number data alone. We confirm a number of previously published molecular changes associated with high risk disease, including MYC amplification, and NKX3-1, RB1 and PTEN deletions, as well as over-expression of PCA3 and AMACR, and loss of MSMB in tumour tissue. A subset of the 100 genes outperforms established clinical predictors of poor prognosis (PSA, Gleason score), as well as previously published gene signatures (p = 0.0001). We further show how our molecular profiles can be used for the early detection of aggressive cases in a clinical setting, and inform treatment decisions.

INTERPRETATION

For the first time in prostate cancer this study demonstrates the importance of integrated genomic analyses incorporating both benign and tumour tissue data in identifying molecular alterations leading to the generation of robust gene sets that are predictive of clinical outcome in independent patient cohorts.

Abstract 2003: Investigating the cellular interactions of BIRB796 analogues using a novel chloroalkane capture tag

Identifying the targets of a bioactive compound is often the rate limiting step toward understanding the molecular mechanism of drug action. Current approaches rely on linking the bioactive compound to a surface or an affinity handle, permitting selective capture of interacting proteins for identification by mass spectrometry. A major consideration with these methods is insuring that the chemical derivatization of the bioactive compound does not disrupt the binding interactions with the cellular targets. We have developed a method based on a novel chloroalkane capture tag that minimally affects compound potency and cell permeability. This allows verification of the pharmacological activity of the modified compound, thus increasing the confidence in the biological relevance of captured proteins. In addition, by allowing the chloroalkane-modified compound to bind the targets within living cells, the cellular architecture during the binding step is preserved and better represents the conditions that the unaltered compound would normally engage these targets. Following binding with the tagged compound in live cells, the cells are lysed and the chloroalkylated compound and its associated targets are rapidly captured onto immobilized HaloTag protein and then released by competitive elution. The identified targets are then validated for direct binding relationship with the bioactive compound by bioluminescence energy transfer. We tested this target capture/target validation work flow using the interaction of MAPK kinases with two allosteric kinase inhibitors (BIRB796 and a BIRB analog exhibiting 100-fold lower potency).

RESULTS: Using the two BIRB-chloroalkane derivatives to selectively enrich for targets from HEPG2 cells, we identified and validated multiple relevant MAPK kinases as well as additional off-targets. Interestingly, all the discovered off-targets bind purines. Kinase inhibitors such as BIRB796 which acts by binding to the kinase ATP binding site can interact in a similar manner with other purine binding proteins. Using bioluminescence energy transfer we interrogated the affinity and residence time of the two BIRB compounds to multiple MAPK kinases inside living cells. Our results indicates that the BIRB796 analog exhibits 30-1000 fold reduced affinity to multiple MAPK kinases as well as significant shorter residence time compared to BIRB796. Taken together these results indicate that our workflow can reveal the direct binding relationships between bioactive compounds and their cellular targets and contribute to further understanding of these interactions.

Citation Format: Rachel Friedman Ohana, Robin Hurst, Thomas Kirkland, Carolyn Woodroofe, Sergiy Levin, Paul Otto, Tetsuo Uyeda, Michael Ford, Richard Jones, Danette Daniels, Marjeta Urh, Keith Wood. Investigating the cellular interactions of BIRB796 analogues using a novel chloroalkane capture tag. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2003. doi:10.1158/1538-7445.AM2015-2003

Abstract 2446: Decoding phenotypic drug screening targets using a novel chloroalkane capture tag

Phenotypic screening has become increasingly common to the drug discovery workflow. Yet, productive outcomes remain hindered by the challenging task of identifying the underlying cellular targets mediating the desired phenotype. Current approaches rely on linking the bioactive compound to a surface or an affinity handle allowing selective capture of interacting proteins for identification by mass spectrometry. These methods can be constrained by ineffective capture of low affinity and low abundance proteins. In addition, for these methods to provide meaningful results, it is critical that the chemical derivatization of the bioactive compound would not disrupt the binding interactions with the cellular targets. Consequently, there is preference for methods compatible with living cells because they allow verification of the pharmacological activity of the modified compound. We have developed such a method based on a novel chloroalkane capture tag that minimally affects compound potency and cell permeability. Following binding with the tagged compound in live cells, the cells are lysed and the chloroalkylated compound, together with the bound targets, is rapidly captured onto immobilized HaloTag protein. The in-situ target engagement combined with rapid covalent capture allows for isolation of difficult targets with low affinity and/or low abundance. The putative targets identified by mass spectrometry are then validated for direct binding relationship with the bioactive compound by bioluminescence energy transfer. We tested this target capture/target-validation workflow using the interaction of histone deacetylases (HDACs) class I/IIb and the inhibitor SAHA (Vorinostat).

RESULTS: Treatment of K562 cells with SAHA or SAHA-chloroalkane revealed high cellular potency against HDAC class I/IIb with minimal impact of the chloroalkane modification on the drug potency. Using the SAHA-chloroalkane to selectively enrich for SAHA targets from K-562 cells, we identified and validated all the known targets of SAHA (i.e., HDAC 1, 2, 3, 6, 8 and 10) regardless of their abundance or affinity (nM to low μM). In addition, we also identified and validated two previously undescribed targets of SAHA (CPPED1 and ADO), both metalloenzymes. Because SAHA binds to HDACs by chelating to a bound zinc ion, it may interact by a similar mechanism with other metalloenzymes. The discovery of ADO may also provide insight to a potential novel mode of action for SAHA in neurodegenerative diseases. Other experiments showed that replacing the chloroalkyl group in the SAHA-chloroalkane with biotin significantly reduced drug potency and consequently enrichment efficiency (only HDAC6 was isolated), further demonstrating the advantages provided by the relatively inert chloroalkane tag. Taken together these results indicate that our workflow can reveal the direct binding relationships between bioactive compounds and their cellular targets.

Citation Format: Rachel Friedman Ohana, Thomas Kirkland, Carolyn Woodroofe, Sergiy Levin, Robin Hurst, Paul Otto, Tetsuo Uyeda, Michael Ford, Richard Jones, Danette Daniels, Marjeta Urh, Keith Wood. Decoding phenotypic drug screening targets using a novel chloroalkane capture tag. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2446. doi:10.1158/1538-7445.AM2015-2446

Purification of Recombinant Proteins from Cultured Mammalian Cells by HaloTag Technology

Cultured mammalian cells provide an environment ideal for producing functional recombinant mammalian proteins. However, low expression levels of recombinant proteins present a challenge for their detection and purification. This unit will focus on HaloTag, a protein fusion tag designed to bind selectively and covalently to a chloroalkane ligand that may be attached to a variety of functional groups, allowing both protein detection and immobilization. Detection of HaloTag-fusion protein is achieved through binding to a fluorescent chloroalkane ligand, enabling rapid optimization of expression levels. HaloTag-based purification uses covalent capture of the HaloTag fusion onto HaloLink resin coupled with proteolytic cleavage to release the protein of interest from the resin. Covalent binding provides efficient protein capture regardless of expression level and eliminates protein loss during washes of the resin and as a result, offers significant improvements in protein recovery and purity over traditional non-covalent approaches.

Development of a dehalogenase-based protein fusion tag capable of rapid, selective and covalent attachment to customizable ligands

Our fundamental understanding of proteins and their biological significance has been enhanced by genetic fusion tags, as they provide a convenient method for introducing unique properties to proteins so that they can be examinedin isolation. Commonly used tags satisfy many of the requirements for applications relating to the detection and isolation of proteins from complex samples. However, their utility at low concentration becomes compromised if the binding affinity for a detection or capture reagent is not adequate to produce a stable interaction. Here, we describe HaloTag® (HT7), a genetic fusion tag based on a modified haloalkane dehalogenase designed and engineered to overcome the limitation of affinity tags by forming a high affinity, covalent attachment to a binding ligand. HT7 and its ligand have additional desirable features. The tag is relatively small, monomeric, and structurally compatible with fusion partners, while the ligand is specific, chemically simple, and amenable to modular synthetic design. Taken together, the design features and molecular evolution of HT7 have resulted in a superior alternative to common tags for the overexpression, detection, and isolation of target proteins.

Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification, processing and production of Se-enriched food

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30ng/g in white flour and 35ng/g in wholemeal flour from untreated plots up to >1800ng/g in white and >2200ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10g/ha increased total selenium in white and wholemeal bread by 155 and 185ng/g, respectively, equivalent to 6.4 and 7.1μg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65-87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.

Engineering of a wheat germ expression system to provide compatibility with a high throughput pET-based cloning platform

Wheat germ cell-free methods provide an important approach for the production of eukaryotic proteins. We have developed a protein expression vector for the TNT((R)) SP6 High-Yield Wheat Germ Cell-Free (TNT WGCF) expression system (Promega) that is also compatible with our T7-based Escherichia coli intracellular expression vector pET15_NESG. This allows cloning of the same PCR product into either one of several pET_NESG vectors and this modified WGCF vector (pWGHisAmp) by In-Fusion LIC cloning (Zhu et al. in Biotechniques 43:354-359, 2007). Integration of these two vector systems allowed us to explore the efficacy of the TNT WGCF system by comparing the expression and solubility characteristics of 59 human protein constructs in both WGCF and pET15_NESG E. coli intracellular expression. While only 30% of these human proteins could be produced in soluble form using the pET15_NESG based system, some 70% could be produced in soluble form using the TNT WGCF system. This high success rate underscores the importance of eukaryotic expression host systems like the TNT WGCF system for eukaryotic protein production in a structural genomics sample production pipeline. To further demonstrate the value of this WGCF system in producing protein suitable for structural studies, we scaled up, purified, and analyzed by 2D NMR two (15)N-, (13)C-enriched human proteins. The results of this study indicate that the TNT WGCF system is a successful salvage pathway for producing samples of difficult-to-express small human proteins for NMR studies, providing an important complementary pathway for eukaryotic sample production in the NESG NMR structure production pipeline.

Protein-protein interaction studies on protein arrays: effect of detection strategies on signal-to-background ratios

Protein arrays hold great promise for proteome-scale analysis of protein-protein interaction networks, but the technical challenges have hindered their adoption by proteomics researchers. The crucial issue of design and fabrication of protein arrays have been addressed in several studies, but the detection strategies used for identifying protein-protein interactions have received little attention. In this study, we evaluated six different detection strategies to identify four different protein-protein interaction pairs. We discuss each detection approach in terms of signal-to-background (S/B) ratio, ease of use, and adaptability to high-throughput format. Protein arrays for this study were made by expressing both the bait proteins (proteins captured at the surface) and prey proteins (probes) in cell-free rabbit reticulocyte lysate (RRL) systems. Bait proteins were expressed as HaloTag fusions that allow covalent capture on a HaloTag ligand-coated glass without any prior protein purification step. Prey proteins were expressed and modified with either tags (protein or peptides) or labels (fluorescent or radiometric) for detection. This simple method for creating protein arrays in combination with our analyses of several detection strategies should increase the usefulness of protein array technologies.

Functional protein expression from a DNA based wheat germ cell-free system

Wheat germ based eukaryotic cell-free systems have been shown to be applicable for both functional and structural analyses of proteins. However, the existing methods might require specialized instrumentation and/or a separate mRNA synthesis step. We have developed a DNA based, highly productive, coupled transcription/translation wheat germ cell-free system that incorporates the normally separate mRNA synthesis step and does not require specialized instrumentation. Using a small-volume batch reaction with fluorescence labeling, DNA templates predicted to encode proteins could be quickly screened for their ability to direct the expression of proteins of the appropriate size. Protein yield can be increased as much as 2 to 4-fold in this system using a dialysis reaction, reaching approximately 200-440 microg/ml in 10-20 h. Furthermore, enzyme activities can be assayed directly in the extract without further purification. Simple purification with affinity tags can be achieved in one-step and with minor modifications, efficient SeMet and [U-15N] labeling of >95% can be accomplished in this system. Thus, this efficient cell-free expression system can facilitate both functional and structural proteomics.

Multicolor in vitro translation

In vitro translation is a widely used tool for both analytical and preparative purposes. For analytical purposes, small amounts of proteins are synthesized and visualized by detection of labeled amino acids incorporated during translation. The original strategy of incorporating radioactively labeled amino acids, such as [35S]methionine or [14C]leucine, has been superseded by the addition of antigenic tags or the incorporation of biotin-labeled or BODIPY-FL-labeled amino acids. Such nonradioactive tags are easier to visualize after translation and do not pose a radiation hazard. Among the nonradioactive tags, BODIPY-FL-lysine offers the advantage that proteins that have incorporated this amino acid can be directly visualized after gel electrophoresis. We show here that multiple fluorophores introduced into proteins can considerably extend their usefulness, particularly for the comparison of in vitro-translated proteins from related sources. This technology can be applied in various situations, including the simplified detection of rare truncating mutations in clinical samples from cancer patients.

Hyperresistance to cholesterol hydroperoxide-induced peroxidative injury and apoptotic death in a tumor cell line that overexpresses glutathione peroxidase isotype-4

The selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPX; GPX4) plays a key role in eukaryotic defense against potentially lethal peroxidative injury and also regulation of physiological peroxide tone. In this work we focused on the cytoprotective antiperoxidant effects of GPX4, using a breast tumor epithelial cell line that over-expresses the enzyme. Wild-type COH-BR1 cells, which exhibit little (if any) GPX4 activity, were transfected with a construct encoding the mitochondrion-targeted long (L) form of the enzyme. Several transfectant clones were selected which expressed relatively large amounts of GPX4, as determined by both Northern and Western analysis. Enzyme activity ranged from 15-fold to 190-fold greater than that of wild-type or null-transfected cells. The functional ramifications of GPX4 overexpression were tested by challenging cells with photochemically generated cholesterol hydroperoxides (ChOOHs) in liposomal form. Compared with vector controls, overexpressing clones were found to be substantially more resistant to ChOOH-induced killing, as determined by annexin-V (early apoptotic) and thiazolyl blue (mitochondrial dehydrogenase) reactivity. Concomitantly, the clones exhibited a striking hyper-resistance to free radical-mediated lipid peroxidation, as assessed by labeling cell membranes with [(14)C]cholesterol and measuring a family of radiolabeled oxidation products (ChOX). L-form GPX4's antiperoxidant and cytoprotective effects could reflect its ability to detoxify ChOOHs as they enter cells and/or cell-derived lipid hydroperoxides arising from ChOOH one-electron turnover.

Expansion and long-term culture of differentiated normal rat urothelial cells in vitro

The objective of this study is to establish a reliable cell culture system for the long-term culture of rat urothelial cells (RUC), in which the cells multiply in vitro and form stratified polarized urothelium. Urothelial cells were harvested by the enzymatic digestion of the urothelium exposed by the eversion of resected rat bladders. Primary cultures were initiated in keratinocyte serum-free medium (KSFM) for selective proliferation of urothelial cells. Subsequently, the cells were propagated in a mixture of conditioned medium (CM) derived from Swiss 3T3 cell culture supernatant and KSFM (CM-KSFM). Mean population doubling time was 13.8 +/- 0.9 h. RUC were successfully maintained for 18 passages over a period of 4-5 mo. Detailed investigations of culture conditions showed that CM-KSFM yielded a differentiated multilayer structure. The stratified urothelial sheets measuring 4 x 6 cm2 could be formed and then detached using dispase. Cytokeratin pattern in both the cultured urothelial monolayer and engineered stratified layers was similar to those seen in vivo, as assessed with monoclonal antibody against cytokeratin 17. Ultrastructural morphology showed microvilli, basal cell layer, and desmosomes between adjacent cells in the stratified urothelium.

Exercise dependence, social physique anxiety, and social support in experienced and inexperienced bodybuilders and weightlifters

OBJECTIVES

To investigate psychological correlates of exercise dependence in experienced and inexperienced bodybuilders and weightlifters. Secondary objectives included measuring social physique anxiety, bodybuilding identity, and social support among bodybuilders and weightlifters.

METHODS

Thirty five experienced bodybuilders, 31 inexperienced bodybuilders, and 23 weightlifters completed the bodybuilding dependence scale, a bodybuilding version of the athletic identity measurement scale, the social physique anxiety scale, and an adapted version of the social support survey-clinical form.

RESULTS

A between subjects multivariate analysis of variance was calculated on the scores of the three groups of lifters for the four questionnaires. Univariate F tests and follow up tests indicated that experienced bodybuilders scored significantly higher than inexperienced bodybuilders and weightlifters on bodybuilding dependence (p<0.001), social identity and exclusivity subscales of bodybuilding identity (p<0.001), and social support scales (p<.001), and significantly lower on social physique anxiety (p<0.001).

CONCLUSION

Experienced bodybuilders exhibit more exercise dependence, show greater social support behaviour, and experience less social physique anxiety than inexperienced bodybuilders and weightlifters.

Initial presentation with stage IV colorectal cancer: how aggressive should we be?

HYPOTHESIS

The appropriate surgical treatment of patients with colorectal cancer who are found on initial presentation to have stage IV disease is controversial. With presumed limited life expectancy, the role of primary colon or rectal resection has been questioned, as has the utility of synchronous hepatic resection.

DESIGN

A retrospective chart review.

SETTING

The University of Chicago Hospitals, Chicago, Ill, a tertiary-care referral center.

PATIENTS

One hundred twenty patients were identified through The University of Chicago Hospitals Tumor Registry whose initial presentation showed stage IV colorectal cancer and who underwent laparotomy.

MAIN OUTCOME MEASURES

The primary end points of the study were perioperative morbidity and mortality and overall survival.

RESULTS

Median survival and 5-year survival were 14.4 months and 10%, respectively. Survival was greater for patients younger than 65 years than for those who were aged 65 years or older (18.3 vs 9.8 months; P = .007). Carcinomatosis was associated with significantly decreased survival when compared with less extensive stage IV disease (6.7 vs 18.1 months; P<.001). Patients who underwent any form of resection of hepatic metastases achieved a survival advantage over those with unresectable liver lesions (median survival, 29.6 vs 10.2 months; P<.001). Overall, 27 patients (22.5%) developed postoperative complications. Seven patients (5.8%) died during the postoperative period.

CONCLUSIONS

Age of 65 years or older, carcinomatosis, and extensive (bilobar) liver involvement are associated with decreased survival and increased postoperative morbidity and mortality and may negate any potential benefit patients derive from resection of the primary lesion. A substantial number of patients with synchronous hepatic metastases have protracted survival that justifies resection of the primary colorectal tumor at initial presentation. Despite the presence of stage IV disease, resection of the primary tumor and, when feasible, liver metastases is indicated.

Restorative proctocolectomy with J-pouch ileoanal anastomosis

Restorative proctocolectomy with ileoanal anastomosis, complemented by a pouch formed with the last foot of terminal ileum, is the procedure of choice for patients in need of surgical treatment for ulcerative colitis and familial polyposis. The procedure has undergone many technical modifications that have ensured a very high degree of continence and an acceptable number of daily bowel movements. Herein we describe the operative technique we use in the majority of our patients, a restorative proctocolectomy with hand-sewn J-pouch ileoanal anastomosis with protecting ileostomy. We also comment on the immediate postoperative care and on the long-term functional results.

Evaluating cardiovascular disease prevention programs in African American communities

This article reports on an evaluation of community cardiovascular disease prevention projects. The evaluation protocol involved a monitoring system for documenting community activities. It showed improvements in cardiovascular disease prevention services, community actions, planned products, and new or modified community programs to prevent cardiovascular disease. Reports from focus group sessions provided analyses of participants' perceived behaviors and satisfaction with eight community-based cardiovascular disease prevention projects in African American communities. Modest improvements in blood pressure, blood cholesterol, dietary intake, and physical activity among a convenience sample of participants in the community were noted.

Brain metastasis after immunotherapy in patients with metastatic melanoma or renal cell cancer: is craniotomy indicated?

The purpose of this study was to evaluate the outcome of surgical treatment of brain metastasis in patients with metastatic melanoma or renal cell cancer after interleukin-2 (IL-2) therapy. A retrospective analysis was conducted at the Surgery Branch, National Cancer Institute. All patients with a diagnosis of metastatic melanoma or renal cell cancer who received IL-2 from January 1, 1985 to January 1, 1996 (n = 1385) were screened for the development of brain metastasis. Forty patients underwent surgical treatment of brain metastasis that developed after initiating IL-2 therapy. Thirty-six were rendered free of disease after resection of a single metastasis and were the focus of this study. Twenty-two of the 36 patients achieved a clinical response (10 complete responses and 12 partial responses) at extracranial sites of disease after IL-2-based immunotherapy and before the development of brain metastasis. The median disease-free interval in the brain after resection of a single metastasis was 21, 7, and 3 months for patients achieving a complete response, partial response, and no response (CR, PR, and NR) to IL-2 therapy, respectively. The median survival after craniotomy for these three groups of patients was 23, 17, and 7 months, respectively. The disease-free interval in the brain and the overall survival after craniotomy were significantly longer for patients achieving a CR to previous immunotherapy when compared with patients achieving a PR or NR. Of the 10 patients who had achieved a prior CR, 8 remained disease free in the brain at last follow-up, 6 remained alive beyond 1 year, and 3 > 4 years. Twenty-five patients experienced neurologic symptoms before craniotomy and all had complete resolution of their symptoms after surgery. Surgical treatment of single brain metastasis in patients with metastatic melanoma or renal cell cancer is indicated in carefully selected patients. The benefits of resection include palliation of symptoms and the potential for a prolonged disease-free interval in the brain.

Phospholipid hydroperoxide cysteine peroxidase activity of human serum albumin

Human serum albumin (HSA) reduced the phospholipid hydroperoxide, 1-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl)-l-3-phosphatidylcholine (PLPC-OOH) to the corresponding hydroxy-derivative with a high apparent affinity (Km=9. 23+/-0.95 microM). Removal of bound lipid during purification increased this activity. At physiological concentration, HSA reduced the phospholipid hydroperoxide in the absence of a cofactor. However, in the presence of a cofactor (reductant), the rate of the reaction was increased. All of the major aminothiols in plasma could act as reductants, the best being the most abundant, cysteine (Km=600+/-80 microM). For every nanomole of PLPC-OOH reduced by HSA, 1.26 nmol of cystine was formed, indicating a reaction stoichiometry of 1 mol PLPC-OOH to 2 mol cysteine. We used chemical modification to determine which amino acid residues on HSA were responsible for the activity. Oxidation of thiol group(s) by N-ethylmaleimide led to a reduction in the rate of activity, whereas reduction of thiols by either dithiothreitol or the angiotensin-converting enzyme inhibitor, captopril, increased the activity. Both N-ethylmaleimide-modified HSA and dithiothreitol-treated HSA exhibited increased apparent affinities for PLPC-OOH. For a range of preparations of albumin with different modifications, the activity on PLPC-OOH was dependent on the amount of free thiol groups on the albumin (correlation coefficient=0.91). Patients with lowered albumin concentrations after septic shock showed lowered total plasma thiol concentrations and decreased phospholipid hydroperoxide cysteine peroxidase (PHCPx) activities. These results therefore show for the first time that HSA exhibits PHCPx activity, and that the majority of the activity depends on the presence of reduced thiol group(s) on the albumin.

Cloning, functional expression and purification of endo-beta-galactosidase from Flavobacterium keratolyticus

Endo-beta-galactosidase (EC 3.2.1.103) is an enzyme that hydrolyzes internal endo-beta-galactosyl linkages in keratan sulfate, and glycoconjugates with N-acetyl-lactosamine repeating units. Here, we report the cloning of the endo-beta-galactosidase-encoding gene from Flavobacterium keratolyticus, its expression in Escherichia coli and the purification of the enzyme. The enzyme was purified over 15000-fold to apparent homogeneity. The purified endo-beta-galactosidase consists of a single band of about 43kDa on SDS-PAGE and has a specific activity of 148micro/mg. Based on peptide sequences derived from the purified enzyme, a full-length clone encoding endo-beta-galactosidase was isolated from F. keratolyticus genomic DNA. The gene contains a single open reading frame coding for a protein of 422 amino acid residues with a putative N-terminal signal peptide. Its authenticity was confirmed by colinearity of deduced amino acid sequences with the peptide sequences, and synthesis of enzyme in E. coli.

Porcine cartilage transplants in the cynomolgus monkey. III. Transplantation of alpha-galactosidase-treated porcine cartilage

BACKGROUND

Studies on transplantation of porcine meniscus and articular cartilage into monkeys are important for evaluating the possible use of such tissues in humans. In addition, such studies shed light on the chronic xenograft rejection process in primates. Transplantation of porcine cartilage into cynomolgus monkeys for 2 months results in a many-fold increase in anti-Gal activity and in a strong cellular inflammatory response of T lymphocytes and macrophages within the implants. The objective of this study was to determine whether elimination of Galalpha1-3Galbeta1-4GlcNAc-R (alpha-gal epitopes) from the xenograft may alter the immune response and the inflammatory reaction.

METHODS

Porcine meniscus and articular cartilage specimens were treated with recombinant alpha-galactosidase (100 U/ml), and the absence of alpha-gal epitopes was assessed by the binding of the monoclonal anti-Gal antibody M86. The treated cartilage specimens were transplanted into the suprapatellar pouch of cynomolgus monkeys. The immune response to cartilage was monitored in the serum and the inflammatory reaction was assessed in the xenografts, which were explanted after 2 months.

RESULTS

Incubation with alpha-galactosidase resulted in complete removal of alpha-gal epitopes from the cartilage. The increase in anti-Gal activity in the transplanted monkeys was marginal. However, most monkeys produced antibodies to antigens specific to porcine cartilage. The inflammatory response within the alpha-galactosidase-treated xenografts was much lower than in nontreated cartilage and the proportion of T lymphocytes within the cellular infiltrates was greatly reduced.

CONCLUSIONS

Treatment of cartilage xenografts with alpha-galactosidase successfully removes alpha-gal epitopes from porcine cartilage. Transplantation of the treated cartilage results in the production of only anti-porcine cartilage-specific antibodies and a reduced inflammatory response consisting primarily of macrophages infiltrating into the cartilage.

Phospholipid hydroperoxide glutathione peroxidase activity of human glutathione transferases

Human glutathione transferases (GSTs) from Alpha (A), Mu (M) and Theta (T) classes exhibited glutathione peroxidase activity towards phospholipid hydroperoxide. The specific activities are in the order: GST A1-1>GST T1-1>GST M1-1>GST A2-2>GST A4-4. Using a specific and sensitive HPLC method, specific activities towards the phospholipid hydroperoxide,1-palmitoyl-2-(13-hydroper oxy-cis-9, trans-11 -octadecadienoyl)-l-3-phosphatidylcholine (PLPC-OOH) were determined to be in the range of 0.8-20 nmol/min per mg of protein. Two human class Pi (P) enzymes (GST P1-1 with Ile or Val at position 105) displayed no activity towards the phospholipid hydroperoxide. Michaelis-Menten kinetics were followed only for glutathione, whereas there was a linear dependence of rate with PLPC-OOH concentration. Unlike the selenium-dependent phospholipid hydroperoxide glutathione peroxidase (Se-PHGPx), the presence of detergent inhibited the activity of GST A1-1 on PLPC-OOH. Also, in contrast with Se-PHGPx, only glutathione could act as the reducing agent for GST A1-1. A GST A1-1 mutant (Arg15Lys), which retains the positive charge between the GSH- and hydrophobic binding sites, exhibited a decreased kcat for PLPC-OOH but not for CDNB, suggesting that the correct topography of the GSH site is more critical for the phospholipid substrate. A Met208Ala mutation, which gives a modified hydrophobic site, decreased the kcat for CDNB and PLPC-OOH by comparable amounts. These results indicate that Alpha, Mu and Theta class human GSTs provide protection against accumulation of cellular phospholipid hydroperoxides.

Patterns of relapse and response to retreatment in patients with metastatic melanoma or renal cell carcinoma who responded to interleukin-2-based immunotherapy

PURPOSE

The purpose of this study was to examine the pattern of relapse and the treatment of relapse with either surgery or repeat immunotherapy in patients with metastatic melanoma or renal cell carcinoma who had previously responded to interleukin-2-based therapy.

PATIENTS AND METHODS

Over a 10-year period 1051 patients with metastatic melanoma or renal cell carcinoma were treated with interleukin-2-based immunotherapy at a single institution. One hundred fifty-nine patients who relapsed after an initial partial response or complete response to interleukin-2-based immunotherapy formed the study population for this retrospective review. Medical records, physical examination forms, and relevant radiographs were reviewed to determine response, relapse site(s), and response to treatment for relapse.

RESULTS

Relapse after an initial response to interleukin-2-based therapy occurred in 84 (80%) of 105 patients with metastatic melanoma and in 75 (70%) of 107 patients with metastatic renal cell carcinoma. Relapse after an initial partial response involved 71 (97%) of 73 patients with metastatic melanoma and 55 (86%) of 64 patients with metastatic renal cell carcinoma. The initial site(s) of relapse after a partial response involved a new site(s), old site(s), or both old and new sites with relatively even distribution. Relapse after an initial complete response occurred in 13 (41%) of 32 patients with metastatic melanoma and in 20 (47%) of 43 completely responding patients with metastatic renal cell carcinoma. Surprisingly, the initial site of relapse after a complete response involved only new sites of disease in 70% of patients. Retreatment of relapses with the same interleukin-2-based therapy originally used was effective in only one (2%) of 54 selected patients, but a different interleukin-2-based therapy in 35 patients resulted in five responders (a 14% secondary response rate). Most re-responders, however, responded to treatment with tumor-infiltrating lymphocytes and interleukin-2, and only one of 20 patients responded to retreatment with interleukin-2 alone. Surgical metastasectomy with therapeutic intent in 25 selected melanoma patients and in 31 selected renal cell cancer patients resulted in a 2-year progression-free survival of 18% in patients with metastatic melanoma and 37% in patients with metastatic renal cell carcinoma.

DISCUSSION

In patients with metastatic melanoma or renal cell carcinoma, tumor relapse was common after a partial response to an interleukin-2-based therapy and included previously identified sites of disease in most patients. Relapse after a complete response was less frequent and involved only new sites in a majority of patients. In selected patients who relapsed, repeat treatment with the same interleukin-2-based therapy that provided the initial response was rarely effective. However, with a different interleukin-2-based therapy, usually using tumor-infiltrating lymphocytes, repeat treatment induced secondary responses in some patients. In addition, salvage metastasectomy resulted in durable progression-free survival in selected patients.

Cloning and expression of a novel mammalian homolog of Drosophila transient receptor potential (Trp) involved in calcium entry secondary to activation of receptors coupled by the Gq class of G protein

Hormonal stimulation of Gq-protein coupled receptors triggers Ca2+ mobilization from internal stores. This is followed by a Ca2+ entry through the plasma membrane. Drosophila Trp and Trpl proteins have been implicated in Ca2+ entry and three mammalian homologues of Drosophila Trp/Trpl, hTrp1, hTrp3 and bTrp4 (also bCCE) have been cloned and expressed. Using mouse brain RNA as template, we report here the polymerase chain reaction-based cloning and functional expression of a novel Trp, mTrp6. The cDNA encodes a protein of 930 amino acids, the sequence of which is 36.8, 36.3, 43.1, 38.6, and 74. 1% identical to Drosophila Trp and Trpl, bovine Trp4, and human Trp1 and Trp3, respectively. Transient expression of mTrp6 in COS.M6 cells by transfection of the full-length mTrp6 cDNA increases Ca2+ entry induced by stimulation of co-transfected M5 muscarinic acetylcholine receptor with carbachol (CCh), as seen by dual wavelength fura 2 fluorescence ratio measurements. The mTrp6-mediated increase in Ca2+ entry activity was blocked by SKF-96365 and La3+. Ca2+ entry activity induced by thapsigargin was similar in COS cells transfected with or without the mTrp6 cDNA. The thapsigargin-stimulated Ca2+ entry could not be further stimulated by CCh in control cells but was markedly increased in mTrp6-transfected cells. Records of whole cell transmembrane currents developed in response to voltage ramps from -80 to +40 mV in control HEK cells and HEK cells stably expressing mTrp6 revealed the presence of a muscarinic receptor responsive non-selective cation conductance in Trp6 cells that was absent in control cells. Our data support the hypothesis that mTrp6 encodes an ion channel subunit that mediates Ca2+ entry stimulated by a G-protein coupled receptor, but not Ca2+ entry stimulated by intracellular Ca2+ store depletion.