Micromolar Sensitivity Research Articles

Nanomolar Protein Thermal Profiling with Modified Cyanine Dyes.

Protein properties and interactions have been widely investigated by using external labels. However, the micromolar sensitivity of the current dyes limits their applicability due to the high material consumption and assay cost. In response to this challenge, we synthesized a series of cyanine5 (Cy5) dye-based quencher molecules to develop an external dye technique to probe proteins at the nanomolar protein level in a high-throughput one-step assay format. Several families of Cy5 dye-based quenchers with ring and/or side-chain modifications were designed and synthesized by introducing organic small molecules or peptides. Our results showed that steric hindrance and electrostatic interactions are more important than hydrophobicity in the interaction between the luminescent negatively charged europium-chelate-labeled peptide (Eu-probe) and the quencher molecules. The presence of substituents on the quencher indolenine rings reduces their quenching property, whereas the increased positive charge on the indolenine side chain improved the interaction between the quenchers and the luminescent compound. The designed quencher structures entirely altered the dynamics of the Eu-probe (protein-probe) for studying protein stability and interactions, as we were able to reduce the quencher concentration 100-fold. Moreover, the new quencher molecules allowed us to conduct the experiments using neutral buffer conditions, known as the peptide-probe assay. These improvements enabled us to apply the method in a one-step format for nanomolar protein-ligand interaction and protein profiling studies instead of the previously developed two-step protocol. These improvements provide a faster and simpler method with lower material consumption.

A long lifetime and highly sensitive wearable microneedle sensor for the continuous real-time monitoring of glucose in interstitial fluid

The short lifetime and low sensitivity of the current glucose electrochemical sensors are two major issues for implementing continuous real-time monitoring of glucose in vivo. Here we show that a unique microneedle-based glucose monitoring skin patch (termed here MGMSP) can continuously measure glucose in real time in live animals with micromolar sensitivity and over 14 days of service life. This MGMSP employs a glucose oxidase (GOD) and carbon nanotube (CNT) modified hollow syringe as electrochemical sensor for glucose monitoring, an integrated circuit for signal processing and transmission, and the real-time glucose levels are displayed on smartphone via Bluetooth. The designed microneedle device protects the stability of the sensing molecules immobilized within the inner surface of hollow syringe and simultaneously the interior space of hollow syringe substantially increases the amount of immobilized sensing molecules. This microneedle design thus extends the lifetime as well as improves the detection sensitivity. The final MGMSP enables the continuous real-time monitoring of glucose in the interstitial fluid of live rats. This innovative microneedle-based MGMSP could potentially provide the public with high-accuracy continual glucose monitoring.

Host-Guest Self-Assembled Interfacial Nanoarrays for Precise Metabolic Profiling.

Accurate and rapid metabolic profiling of cerebrospinal fluid (CSF) is urgently needed but remains challenging for clinical diagnosis of central nervous system diseases and biomarker discovery. Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) holds promise for metabolic analysis. Its low signal reproducibility, however, severely restricts acquisition of quantitative MS data in clinical practice. Herein, a multifunctional self-assembled AuNPs array (MSANA)-based LDI-MS platform for direct amino acids analysis and metabolic profiling in patient CSF samples is developed. MSANA featuring a highly ordered and closely packed two-dimensional nanostructure permits capture and direct analysis of aromatic amino acids by LDI-MS with high selectivity and micromolar sensitivity. Meanwhile, the MSANA-based LDI-MS platform exhibits excellent reproducibility (RSD<10%), largely outperforming the direct matrix spotting approach widely used now (RSD<44%). The platform is successfully used in metabolic profiling of CSF (1µL) within minutes for discrimination of medulloblastoma patients from non-tumor controls. Taken together, the MSANA-based LDI-MS platform shows potential clinical values toward large-scale metabolic diagnostics and pathogenic mechanism study.

Towards molecularly imprinted polymers that respond to and capture phosphorylated tyrosine epitopes using fluorescent bis-urea and bis-imidazolium receptors.

Early detection of cancer is essential for successful treatment and improvement in patient prognosis. Deregulation of post-translational modifications (PTMs) of proteins, especially phosphorylation, is present in many types of cancer. Therefore, the development of materials for the rapid sensing of low abundant phosphorylated peptides in biological samples can be of great therapeutic value. In this work, we have synthesised fluorescent molecularly imprinted polymers (fMIPs) for the detection of the phosphorylated tyrosine epitope of ZAP70, a cancer biomarker. The polymers were grafted as nanometer-thin shells from functionalised submicron-sized silica particles using a reversible addition-fragmentation chain-transfer (RAFT) polymerisation. Employing the combination of fluorescent urea and intrinsically cationic bis-imidazolium receptor cross-linkers, we have developed fluorescent sensory particles, showing an imprinting factor (IF) of 5.0. The imprinted polymer can successfully distinguish between phosphorylated and non-phosphorylated tripeptides, reaching lower micromolar sensitivity in organic solvents and specifically capture unprotected peptide complements in a neutral buffer. Additionally, we have shown the importance of assessing the influence of counterions present in the MIP system on the imprinting process and final material performance. The potential drawbacks of using epitopes with protective groups, which can co-imprint with targeted functionality, are also discussed.

Second Harmonic Scattering Reveals Ion-Specific Effects at the SiO2 and TiO2 Nanoparticle/Aqueous Interface

Ion-specific effects play a crucial role in controlling the stability of colloidal systems and regulating interfacial processes. Although mechanistic pictures have been developed to explain the electrostatic structure of solid/water colloidal interfaces, ion-specific effects remain poorly understood. Here we quantify the average interfacial water orientation and the electrostatic surface potential around 100 nm SiO2 and TiO2 colloidal particles in the presence of NaCl, RbCl, and CaCl2 using polarimetric angle-resolved second harmonic scattering. We show that these two parameters can be used to establish the ion adsorption mechanism in a low ionic strength regime (<1 mM added salt). The relative differences between salts as a function of the ionic strength demonstrate cation- and surface-specific preferences for inner- vs outer-sphere adsorption. Compared to monovalent Rb+ and Na+, Ca2+ is found to be preferentially adsorbed as outer-sphere on SiO2 surfaces, while a dominant inner-sphere adsorption is observed for Ca2+ on TiO2. Molecular dynamics simulations performed on crystalline SiO2 and TiO2 surfaces support the experimental conclusions. This work contributes to the understanding of the electrostatic environment around colloidal nanoparticles on a molecular level by providing insight into ion-specific effects with micromolar sensitivity.

Detection and quantification of γ-H2AX using a dissociation enhanced lanthanide fluorescence immunoassay

Phosphorylation of the histone protein H2AX to form γ-H2AX foci directly represents DNA double-strand break formation. Traditional γ-H2AX detection involves counting individual foci within individual nuclei. The novelty of this work is the application of a time-resolved fluorescence assay using dissociation-enhanced lanthanide fluorescence immunoassay for quantitative measurements of γ-H2AX. For comparison, standard fluorescence detection was employed and analyzed either by bulk fluorescent measurements or by direct foci counting using BioTek Spot Count algorithm and Gen 5 software. Etoposide induced DNA damage in A549 carcinoma cells was compared across all test platforms. Time resolved fluorescence detection of europium as a chelated complex enabled quantitative measurement of γ-H2AX foci with nanomolar resolution. Comparative bulk fluorescent signals achieved only micromolar sensitivity. Lanthanide based immunodetection of γ-H2AX offers superior detection and a user-friendly workflow. These approaches have the potential to improve screening of compounds that either enhance DNA damage or protect against its deleterious effects.

An antimony-phosphomolybdate microassay of ATPase activity through the detection of inorganic phosphate

Colorimetric methods are convenient for the determination of inorganic phosphate. However, the acidic conditions required can complicate measurement of ATPase through non-enzymatic ATP hydrolysis. Here we present an optimized antimony-phosphomolybdate microassay for the simple and rapid detection of ATPase activity, with micromolar sensitivity. The low acidity of the color reagent results in no interference for samples containing up to 0.5–5 mM ATP, dependent on the sample volume. The assay is compatible with common assay conditions and was similar in accuracy to an established continuous method. The simplicity of this method makes it ideal for medium to high throughput applications.

Surface Potential and Interfacial Water Order at the Amorphous TiO2 Nanoparticle/Aqueous Interface.

Colloidal nanoparticles exhibit unique size-dependent properties differing from their bulk counterpart, which can be particularly relevant for catalytic applications. To optimize surface-mediated chemical reactions, the understanding of the microscopic structure of the nanoparticle–liquid interface is of paramount importance. Here we use polarimetric angle-resolved second harmonic scattering (AR-SHS) to determine surface potential values as well as interfacial water orientation of ∼100 nm diameter amorphous TiO2 nanoparticles dispersed in aqueous solutions, without any initial assumption on the distribution of interfacial charges. We find three regions of different behavior with increasing NaCl concentration. At very low ionic strengths (0–10 μM), the Na+ ions are preferentially adsorbed at the TiO2 surface as inner-sphere complexes. At low ionic strengths (10–100 μM), a distribution of counterions equivalent to a diffuse layer is observed, while at higher ionic strengths (>100 μM), an additional layer of hydrated condensed ions is formed. We find a similar behavior for TiO2 nanoparticles in solutions of different basic pH. Compared to identically sized SiO2 nanoparticles, the TiO2 interface has a higher affinity for Na+ ions, which we further confirm with molecular dynamics simulations. With its ability to monitor ion adsorption at the surface with micromolar sensitivity and changes in the surface potential, AR-SHS is a powerful tool to investigate interfacial properties in a variety of catalytic and photocatalytic applications.

Development of Zinc-Specific iCEST MRI as an Imaging Biomarker for Prostate Cancer.

The healthy prostate contains the highest concentration of mobile zinc in the body. As this level decreases dramatically during the initial development of prostate cancer, in vivo detection of prostate zinc content may be applied for diagnosis of prostate cancer. Using 19 F ion chemical exchange saturation transfer magnetic resonance imaging (iCEST MRI) and TF-BAPTA as a fluorinated Zn-binding probe with micromolar sensitivity, we show that iCEST MRI is able to differentiate between normal and malignant prostate cells with a 10-fold difference in contrast following glucose-stimulated zinc secretion in vitro. The iCEST signal decreased in normal prostate cells upon downregulation of the ZIP1 zinc transporter. In vivo, using an orthotopic prostate cancer mouse model and a transgenic adenocarcinoma of the mouse prostate (TRAMP) model, a gradual decrease of >300 % in iCEST contrast following the transition of normal prostate epithelial cells to cancer cells was detected.

Development of Zinc‐Specific iCEST MRI as an Imaging Biomarker for Prostate Cancer

AbstractThe healthy prostate contains the highest concentration of mobile zinc in the body. As this level decreases dramatically during the initial development of prostate cancer, in vivo detection of prostate zinc content may be applied for diagnosis of prostate cancer. Using 19F ion chemical exchange saturation transfer magnetic resonance imaging (iCEST MRI) and TF‐BAPTA as a fluorinated Zn‐binding probe with micromolar sensitivity, we show that iCEST MRI is able to differentiate between normal and malignant prostate cells with a 10‐fold difference in contrast following glucose‐stimulated zinc secretion in vitro. The iCEST signal decreased in normal prostate cells upon downregulation of the ZIP1 zinc transporter. In vivo, using an orthotopic prostate cancer mouse model and a transgenic adenocarcinoma of the mouse prostate (TRAMP) model, a gradual decrease of &gt;300 % in iCEST contrast following the transition of normal prostate epithelial cells to cancer cells was detected.

Identification of a Pan-Gamma-Secretase Inhibitor Response Signature for Notch-Driven Cholangiocarcinoma.

Cholangiocarcinoma (CCA) mortality rates are increasing as a result of rising incidence and limited curative treatment(s) for patients with advanced disease. NOTCH pathway reactivation has been reported in biliary malignancies to conflicting degrees, hindering prioritization of key therapeutic targets within the network and identification of candidate responder patients for NOTCH-directed therapies. We analyzed genomic data from 341 patients with CCA and identified NOTCH1 significantly increased in a subgroup characterized by distinct stromal infiltration. Network-wide imbalance of the NOTCH pathway was seen in CCA, including correlation of NOTCH1 with NOTCH3 and NOTCH ligands. Given the diversity of observed NOTCH receptor engagement, γ-secretase modulation was rationalized as a therapeutic option. Indeed, subcutaneous transplantation of sensitive and resistant CCA cell lines pretreated with a γ-secretase inhibitor (GSi) cocktail demonstrated the antineoplastic effects of GSi in a subset of CCA and led to the development of a 225-gene responder signature. This signature was validated in an independent cohort of 119 patients. Further, this signature was enriched in liver tumors initiated by hydrodynamic injections of activated-NOTCH as compared with the AKT-RAS-driven tumors. Candidate GSi-responder patients were characterized by distinct transcriptomes overlapping with previous hepatobiliary metastasis and stemness, unique stromal properties, and dysfunctional intratumoral immune infiltration. Pan-cancer analysis identified 41.9% of cancer types to harbor prospective GSi-responder patients, which was adapted into a 20-gene GSi-sensitivity score metric capable of discriminating nanomolar versus micromolar sensitivity to a cell-permeable GSi (Z-LLNle-CHO) across 60 diverse tumor lines (area under the curve=1). Conclusion: We have established a GSi-responder signature with evidence across several patient cohorts, as well as in vitro and in vivo models, to enable precision medicine application of NOTCH-directed therapy in CCA as well as prospectively across diverse malignancies.

Colorimetric chemosensor based on coumarin skeleton for selective naked eye detection of cobalt (II) ion in near aqueous medium

The numbers indicating the permissible limits of concentration of the different metal ion consumptions and exposure levels on the environment are as important as their consumption for healthy existence of living systems. Overpassing these consumption and exposure limits can be unsafe for the living systems and environment. In this perspective, we developed a colorimetric probe for detection of Co2+ ion in the nearly aqueous medium which performed a color change in the solution containing cobalt from light yellow to yellowish red due to intramolecular charge transfer (ICT) upon addition of synthesized probe. The optical response and absorption spectral changes of the Co2+ ion on the coumarin-based probe were observed under different pH conditions and the neutral pH was found to be suited best which implies its applicability under physiological conditions. The probe displayed an excellent capability to detect the Co2+ ions in real samples of water collected from different sources. The analytical and stoichiometric calculations were evaluated using the Benesi-Hildebrand curve and Job’s plot which revealed micromolar sensitivity and 1:1 metal-receptor binding respectively. The experimental FTIR results of ligand and its complex with cobalt were also corroborated with the Density Functional Theory (DFT) results.

Minimally invasive technique for measuring transdermal glucose with a fluorescent biosensor.

There is a need for blood glucose monitoring techniques that eliminate the painful and invasive nature of current methods, while maintaining the reliability and accuracy of established medical technology. This research aims to ultimately address these shortcomings in critically ill pediatric patients. Presented in this work is an alternative, minimally invasive technique that uses microneedles (MN) for the collection of transdermal glucose (TG). Due to their comparable skin properties, diffusion studies were performed on full thickness Yucatan miniature pig skin mounted to an in-line diffusion flow cell and on different skin sites of human subjects. Collected TG samples were measured with a L255C mutant of the E. coli glucose-binding protein (GBP) with an attached fluorescent probe. The binding constant (Kd = 0.67μM) revealed the micromolar sensitivity and high selectivity of the his-tagged GBP biosensor for glucose, making it suitable for TG measurements. In both the animal and human models, skin permeability and TG diffusion across the skin increased with MN application. For intact and MN-treated human skin, a significant positive linear correlation (r > 0.95, p < 0.01) existed between TG and BG. The micromolar sensitivity of GBP minimized the volume required for interstitial fluid glucose analysis allowing MN application time (30s) to be shortened compared to other studies. This time reduction can help in eliminating skin irritation issues and improving practical use of the technique by caregivers in the hospital. In addition, the his-tagged optical biosensor used in this work can be immobilized and used with a portable sensing fluorometer device at the point of care (POC) making this minimally invasive technology more ideal for use in the pediatric intensive care unit. Graphical abstract ᅟ.

Azaindole modified imine moiety as fluorescent probe for highly sensitive detection of Fe3+ ions

An azaindole based schiff base AzIm was synthesized that serve as a luminescent turn “off” switch for the detection of Fe3+ ions. The photoluminescence intensity of AzIm was quenched significantly in the presence of 30μM Fe3+ ions. The sensing response of the probe was tested at different ranges of pH and at different cation concentrations between 2 and 25μM. Analytical characteristics were evaluated using standard Benesi-Hildebrand equation and the system displayed micromolar sensitivity for these ions. The specific diminished emission signal upon Fe3+ binding was interpreted in terms of the enhanced photoelectron transfer from azaindole group, which induces very fast and efficient non-radiative decay of the excited states of the sensor. In addition, practical utilization of luminescent AzIm was further supported by significant ion selective stability against the presence of extraneous charged species that makes this system compatible for quantitative analysis of environmental samples.

A sensitive fluorescent probe for Cu2+ based on rhodamine B derivatives and its application to drinking water examination and living cells imaging

A new rhodamine derivative (RhS) with a recognition capability for Cu2+ was synthesized and employed as a reversible fluorescent probe for Cu2+ in drinking water and living cells. The spirolactam ring-opening of probe RhS induced by Cu2+ lead to a highly selective fluorescence “turn-on” response toward Cu2+ over other metal ions with micromolar sensitivity. The 1:1 stoichiometric structure between RhS and Cu2+ were supported by Job's plot, MS and DFT theoretical calculations. The analytical results obtained by UV–vis and fluorescence spectrophotometry show that the linear range and the limit of detection (LOD) of the present probe for Cu2+ are 0.50–20.00 and 0.11μmolL−1, respectively. The present probe was applied to the detection of Cu2+ in drinking water with the recoveries ranging from 100.4 to 101.2%, and the fluorescence imaging for living HeLa cells.

Defining the complementarities between antibodies and haptens to refine our understanding and aid the prediction of a successful binding interaction.

BackgroundLow molecular weight haptens (<1000 Da) cannot be recognized by the immune system unless conjugated to larger carrier molecules. Antibodies to these exceptionally small antigens can still be generated with exquisite sensitivity. A detailed understanding at the molecular level of this incredible ability of antibodies to recognize haptens, is still limited compared to other antigen classes.MethodsDifferent hapten targets with a broad range of structural flexibility and polarity were conjugated to carrier proteins, and utilized in sheep immunization. Three antibody libraries were constructed and used as potential pools to isolate specific antibodies to each target. The isolated antibodies were analysed in term of CDR length, canonical structure, and binding site shape and electrostatic potential.ResultsThe simple, chemically naïve structure of squalane (SQA) was recognized with micromolar sensitivity. An increase in structural rigidity of the hydrophobic and cyclic coprostane (COP) did not improve this binding sensitivity beyond the micromolar range, whilst the polar etioporphyrin (POR) was detected with nanomolar sensitivity. Homoserine lactone (HSL) molecules, which combine molecular flexibility and polarity, generated super-sensitive (picomolar) interactions. To better understand this range of antibody-hapten interactions, analyses were extended to examine the binding loop canonical structures and CDR lengths of a series of anti-hapten clones. Analyses of the pre and post- selection (panning of the phage displayed libraries) sequences revealed more conserved sites (123) within the post-selection sequences, when compared to their pre-selection counterparts (28). The strong selection pressure, generated by panning against these haptens resulted in the isolation of antibodies with significant sequence conservation in the FW regions, and suitable binding site cavities, representing only a relatively small subset of the available full repertoire sequence and structural diversity. As part of this process, the important influence of CDR H2 on antigen binding was observed through its direct interaction with individual antigens and indirect impact on the orientation and the pocket shape, when combined with CDRs H3 and L3. The binding pockets also displayed electrostatic surfaces that were complementary to the hydrophobic nature of COP, SQA, and POR, and the negatively charged HSL.ConclusionsThe best binding antibodies have shown improved capacity to recognize these haptens by establishing complementary binding pockets in terms of size, shape, and electrostatic potential.

A Fluorescent, Reagentless Biosensor for ATP, Based on Malonyl-Coenzyme A Synthetase.

A fluorescent reagentless biosensor for ATP has been developed, based on malonyl-coenzyme A synthetase from Rhodopseudomonas palustris as the protein scaffold and recognition element. Two 5-iodoacetamidotetramethylrhodamines were covalently bound to this protein to provide the readout. This adduct couples ATP binding to a 3.7-fold increase in fluorescence intensity with excitation at 553 nm and emission at 575 nm. It measures ATP concentrations with micromolar sensitivity and is highly selective for ATP relative to ADP. Its ability to monitor enzymatic ATP production or depletion was demonstrated in steady-state kinetic assays in which ATP is a product or substrate, respectively.

Abstract 1613: β-lapachone: a novel targeted therapy for atypical teratoid rhabdoid tumors (ATRTs)

Abstract Atypical teratoid rhabdoid tumors (ATRTs) are aggressive malignant neoplasms that occur in the CNS, most commonly in children &amp;lt;3 years of age. Despite intensive chemo-radiotherapy and surgery, the outcomes for patients with this disease remain dismal, with ∼75% of patients dying from their disease at a median of 10 months after diagnosis. Thus, it is critical to identify and validate novel ATRT targets for new therapies. We found that the pathognomonic genetic lesion of ATRTs, loss of the SWI/SNF chromatin remodeling complex member INI1/hSNF5/SMARCB1, leads to high expression of NAD(P)H:quinone oxidoreductase 1 (NQO1), a two-electron oxidoreductase. Thus, we hypothesized that ATRTs will be vulnerable to drugs, such as ß-lapachone (ß-lap, ARQ761 in clinical form), that selectively kill NQO1-expressing cells. A panel of ATRT cell lines exhibited overall high NQO1 expression and low micromolar sensitivity to ß-lap (IC50 1.6-4 uM), with the exception of cell lines that were homozygous for the C609T NQO1 (*2) polymorphism, which exhibited no NQO1 activity and were resistant to ß-lap treatment (IC50 &amp;gt;15 uM). A two-hour pulse with ß-lap caused a burst of ROS-mediated DNA damage and PARP1 hyperactivation, resulting in NAD+ and ATP depletion and caspase-independent, mu-calpain-mediated apoptosis. Co-treatment with dicoumarol, a specific inhibitor of NQO1, prevented these effects by blocking the NQO1-dependent bioactivation of ß-lap. Low expression of NQO1 in normal brain and other pediatric tissues suggests a wide therapeutic window for ß-lap. These findings encourage the continued study of ß-lap and other NQO1 bioactivated therapeutics for the treatment of this recalcitrant disease. This work was supported by NIH/NCI R01 CA102972 to DAB and a REACH award from the Alex's Lemonade Stand Foundation to JFA and TWL. Citation Format: Zachary R. Moore, Sarai Stuart, Agnieszka Cholka, Ashwin Venkataraman, Jingying Xu, Anat Erdreich-Epstein, Dinesh Rakheja, David A. Boothman, James F. Amatruda, Theodore W. Laetsch. β-lapachone: a novel targeted therapy for atypical teratoid rhabdoid tumors (ATRTs). [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 1613. doi:10.1158/1538-7445.AM2015-1613

A novel sensing capabilities and structural modification from thiourea to urea derivative by Hg(ClO4)2: Selective dual chemodosimeter for Hg2+ and F− ions

A new rhodamine-6G phenylthiourea derivative (L1) condensed product was developed as a fluorescent and colorimetric dual chemosensor in acetonitrile with more selective towards Hg2+ and F− ions. Hg2+-promoted spirolactam ring opening of the rhodamine moiety induced urea formation through the diphenylcarbodiimide intermediate from the thiourea moiety. It demonstrates high selectivity for sensing Hg2+ with about 700-fold enhancement in fluorescence emission intensity and micromolar sensitivity (limit of detection 4.52×10−7M) in comparison with other various metal ions. Hg2+ ions coordinated reversibly to L1, forming a 1:2 metal–ligand complex. The thiourea moiety provided an anion binding site, and the rhodamine system was responsible for fluorescence. In turn, the chemosensor L1 acted as a selective chemosensor toward F− among various anions. Thus, L1 associated with F− with 1:1 stoichiometry. A recognition mechanism based on the binding modes of Hg2+ and F− ions were proved by the analytical techniques like UV–vis, changes in fluorescence, 1H NMR, FT-IR, ESI-mass and HRMS. In addition, this chemosensor exhibited highly selective and sensitive recognition of azide (N3−) anions upon the addition of Hg2+ with a color change back to colorless in the same solution.

Abstract B38: Targeting FOXM1 in multiple myeloma

Abstract Unprecedented progress in our understanding of the biologic and molecular genetic underpinnings of multiple myeloma (MM) has recently led to the development of novel targeted therapeutic agents, including proteasome inhibitors, immunomodulatory drugs, CS1-binging antibody, and histone deacetylase inhibitors, which have produced tangible, evidence-based benefits for patients with MM. Nonetheless, the overall outcome remains grim, due in large part to limitations in treating high-risk MM. We recently determined that the level of FOXM1 mRNA expression is of prognostic significance for myeloma patients, as both event-free survival and overall survival were reduced in cases exhibiting high FOXM1 expression. Forty-six of 351 myeloma patients (13.1%) had elevated FOXM1 message, with the majority (29/46, 63%) residing in the MAF/MAFB and proliferation high-risk molecular subgroups. Upregulation of FOXM1 was also observed in patients deemed high-risk using the 70-gene signature as a metric. These results suggest that upregulation of FOXM1 is a feature of high-risk MM, leading to the hypothesis that up-regulation of FOXM1 contributes to increased MM aggressiveness. To evaluate whether targeting FOXM1 results in reduced growth and survival of myeloma cells, MM cell lines exhibiting high levels of FOXM1 were found to have low micromolar sensitivity to treatment with thiostrepton or siomycin A — two thiazole antibiotics known to inhibit FOXM1 activity. Because of known off-target effects of these inhibitors, we are confirming the results using short-hairpin RNA. Our data suggest that developing effective therapeutic strategies against high-risk MM should include consideration of FOXM1 as a new target. Citation Format: Van S. Tompkins, Zhimin Gu, Hongwei Xu, Guido Tricot, Fenghuang Zhan, Siegfried Janz. Targeting FOXM1 in multiple myeloma. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr B38.