Kelly E. Duncan

Controlled Exposure of Healthy Young Volunteers to Ozone Causes Cardiovascular Effects

Background— Recent epidemiology studies have reported associations between short-term ozone exposure and mortality. Such studies have previously reported associations between airborne particulate matter pollution and mortality, and support for a causal relationship has come from controlled-exposure studies that describe pathophysiological mechanisms by which particulate matter could induce acute mortality. In contrast, for ozone, almost no controlled-human-exposure studies have tested whether ozone exposure can modulate the cardiovascular system. Methods and Results— Twenty-three young healthy individuals were exposed in a randomized crossover fashion to clean air and to 0.3-ppm ozone for 2 hours while intermittently exercising. Blood was obtained immediately before exposure, immediately afterward, and the next morning. Continuous Holter monitoring began immediately before exposure and continued for 24 hours. Lung function was performed immediately before and immediately after exposure, and bronchoalveolar lavage was performed 24 hours after exposure. Immediately after ozone exposure, we observed a 98.9% increase in interleukin-8, a 21.4% decrease in plasminogen activator inhibitor-1, a 51.3% decrease in the high-frequency component of heart rate variability, and a 1.2% increase in QT duration. Changes in interleukin-1B and plasminogen activator inhibitor-1 were apparent 24 hours after exposure. In agreement with previous studies, we also observed ozone-induced drops in lung function and an increase in pulmonary inflammation. Conclusions— This controlled-human-exposure study shows that ozone can cause an increase in vascular markers of inflammation and changes in markers of fibrinolysis and markers that affect autonomic control of heart rate and repolarization. We believe that these findings provide biological plausibility for the epidemiology studies that associate ozone exposure with mortality. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01492517.

Resistance to BET Bromodomain Inhibitors Is Mediated by Kinome Reprogramming in Ovarian Cancer

Small-molecule BET bromodomain inhibitors (BETis) are actively being pursued in clinical trials for the treatment of a variety of cancers, but the mechanisms of resistance to BETis remain poorly understood. Using a mass spectrometry approach that globally measures kinase signaling at the proteomic level, we evaluated the response of the kinome to targeted BETi treatment in a panel of BRD4-dependent ovarian carcinoma (OC) cell lines. Despite initial inhibitory effects of BETi, OC cells acquired resistance following sustained treatment with the BETi JQ1. Through application of multiplexed inhibitor beads (MIBs) and mass spectrometry, we demonstrate that BETi resistance is mediated by adaptive kinome reprogramming, where activation of compensatory pro-survival kinase networks overcomes BET protein inhibition. Furthermore, drug combinations blocking these kinases may prevent or delay the development of drug resistance and enhance the efficacy of BETi therapy.

Effect of Size-Fractionation on the Toxicity of Amosite and Libby Amphibole Asbestos

Abnormally high incidences of asbestos-related pulmonary disease have been reported in residents of Libby, Montana, because of occupational and environmental exposure to asbestos-contaminated vermiculite. The mechanism by which Libby amphibole (LA) causes pulmonary injury is not known. The purpose of this study is to compare the cellular stress responses induced in primary human airway epithelial cells (HAECs) exposed to a respirable size fraction (≤ 2.5 μm) of Libby amphibole (LA(2.5)) to a similar size fraction of a reference amphibole sample amosite (AM(2.5)). HAEC were exposed to 0, 2.64, 13.2, or 26.4 μg/cm(2) AM(2.5) or LA(2.5) or to equivalent doses of unfractionated amosite (AM) or LA for 2 or 24 h. Comparable messenger RNA transcript levels were observed for interleukin-8, cyclooxygenase-2, and heme oxygenase-1 in HAEC following a 24-h exposure to AM or LA. Conversely, exposure to AM(2.5) resulted in a 4- to 10-fold greater induction in these proinflammatory mediators compared with LA(2.5) after 24 h. Evaluation of the expression of 84 additional genes involved in cellular stress and toxicity responses confirmed a more robust response for AM(2.5) compared with LA(2.5) on an equal mass basis. Differences in total surface area (TSA) by gas adsorption, total particle number, or oxidant generation by the size-fractionated particles did not account for the observed difference in response. In summary, AM(2.5) and LA(2.5) are at least as potent in stimulating production of proinflammatory cytokines as unfractionated AM and LA. Interestingly, AM(2.5) was more potent at inducing a proinflammatory response than LA(2.5). This difference could not be explained by differences in mineral contamination between the two samples, TSA, or oxidant generation by the samples.

Ozone Induces a Proinflammatory Response in Primary Human Bronchial Epithelial Cells through Mitogen-Activated Protein Kinase Activation Without Nuclear Factor-κB Activation

Ground-level ozone (O3) is a ubiquitous environmental air pollutant that is a potent inducer of airway inflammation and has been linked with respiratory and cardiovascular morbidity and mortality. Some studies using transformed or immortalized cells have attributed O3-mediated expression of inflammatory cytokines with activation of the canonical NF-κB pathway. In this study, we sought to characterize the O3-mediated activation of cellular signaling pathways using primary human bronchial epithelial cells obtained from a panel of donors. We demonstrate that the O3-induced expression of proinflammatory cytokines requires the activation of the epidermal growth factor receptor/MEK/ERK and MKK4/p38 mitogen-activated signaling pathways but does not appear to involve activation of canonical NF-κB signaling. In addition to providing a novel mechanistic model for the O3-mediated induction of proinflammatory cytokines, these findings highlight the importance of using primary cells over cell lines in mechanistic studies.

In vitro determinants of asbestos fiber toxicity: effect on the relative toxicity of Libby amphibole in primary human airway epithelial cells

BackgroundAn abnormally high incidence of lung disease has been observed in the residents of Libby, Montana, which has been attributed to occupational and environmental exposure to fibrous amphiboles originating from a nearby contaminated vermiculite mine. The composition of Libby amphibole (LA) is complex and minimal toxicity data are available. In this study, we conduct a comparative particle toxicity analysis of LA compared with standard reference asbestiform amphibole samples.MethodsPrimary human airway epithelial cells (HAEC) were exposed to two different LA samples as well as standard amphibole reference samples. Analysis of the samples included a complete particle size distribution analysis, calculation of surface area by electron microscopy and by gas adsorption and quantification of surface-conjugated iron and hydroxyl radical production by the fibers. Interleukin-8 mRNA levels were quantified by qRT-PCR to measure relative pro-inflammatory response induced in HAEC in response to amphibole fiber exposure. The relative contribution of key physicochemical determinants on the observed pro-inflammatory response were also evaluated.ResultsThe RTI amosite reference sample contained the longest fibers and demonstrated the greatest potency at increasing IL-8 transcript levels when evaluated on an equal mass basis. The two LA samples and the UICC amosite reference sample consisted of similar particle numbers per milligram as well as similar particle size distributions and induced comparable levels of IL-8 mRNA. A strong correlation was observed between the elongated particle (aspect ratio ≥3:1) dose metrics of length and external surface area. Expression of the IL-8 data with respect to either of these metrics eliminated the differential response between the RTI amosite sample and the other samples that was observed when HAEC were exposed on an equal mass basis.ConclusionsOn an equal mass basis, LA is as potent as the UICC amosite reference sample at inducing a pro-inflammatory response in HAEC but is less potent than the RTI amosite sample. The results of this study show that the particle length and particle surface area are highly correlated metrics that contribute significantly to the toxicological potential of these amphibole samples with respect to the inflammogenic response induced in airway epithelial cells.

Progress in Assessing Air Pollutant Risks from In Vitro Exposures: Matching Ozone Dose and Effect in Human Airway Cells

In vitro exposures to air pollutants could, in theory, facilitate a rapid and detailed assessment of molecular mechanisms of toxicity. However, it is difficult to ensure that the dose of a gaseous pollutant to cells in tissue culture is similar to that of the same cells during in vivo exposure of a living person. The goal of the present study was to compare the dose and effect of O3 in airway cells of humans exposed in vivo to that of human cells exposed in vitro. Ten subjects breathed labeled O3 ((18)O3, 0.3 ppm, 2 h) while exercising intermittently. Bronchial brush biopsies and lung lavage fluids were collected 1 h post exposure for in vivo data whereas in vitro data were obtained from primary cultures of human bronchial epithelial cells exposed to 0.25-1.0 ppm (18)O3 for 2 h. The O3 dose to the cells was defined as the level of (18)O incorporation and the O3 effect as the fold increase in expression of inflammatory marker genes (IL-8 and COX-2). Dose and effect in cells removed from in vivo exposed subjects were lower than in cells exposed to the same (18)O3 concentration in vitro suggesting upper airway O3 scrubbing in vivo. Cells collected by lavage as well as previous studies in monkeys show that cells deeper in the lung receive a higher O3 dose than cells in the bronchus. We conclude that the methods used herein show promise for replicating and comparing the in vivo dose and effect of O3 in an in vitro system.

A Novel HSP90 Inhibitor–Drug Conjugate to SN38 Is Highly Effective in Small Cell Lung Cancer

Purpose: Small cell lung cancer (SCLC) is a highly aggressive disease representing 12% to 13% of total lung cancers, with median survival of <2 years. No targeted therapies have proven effective in SCLC. Although most patients respond initially to cytotoxic chemotherapies, resistance rapidly emerges, response to second-line agents is limited, and dose-limiting toxicities (DLT) are a major issue. This study performs preclinical evaluation of a new compound, STA-8666, in SCLC. Experimental Design: To avoid DLT for useful cytotoxic agents, the recently developed drug STA-8666 combines a chemical moiety targeting active HSP90 (concentrated in tumors) fused via cleavable linker to SN38, the active metabolite of irinotecan. We compare potency and mechanism of action of STA-8666 and irinotecan in vitro and in vivo. Results: In two SCLC xenograft and patient-derived xenograft models, STA-8666 was tolerated without side effects up to 150 mg/kg. At this dose, STA-8666 controlled or eliminated established tumors whether used in a first-line setting or in tumors that had progressed following treatment on standard first- and second-line agents for SCLC. At 50 mg/kg, STA-8666 strongly enhanced the action of carboplatin. Pharmacokinetic profiling confirmed durable STA-8666 exposure in tumors compared with irinotecan. STA-8666 induced a more rapid, robust, and stable induction of cell-cycle arrest, expression of signaling proteins associated with DNA damage and cell-cycle checkpoints, and apoptosis in vitro and in vivo, in comparison with irinotecan. Conclusions: Together, these results strongly support clinical development of STA-8666 for use in the first- or second-line setting for SCLC. Clin Cancer Res; 22(20); 5120–9. ©2016 AACR.

Ozone-derived Oxysterols Affect Liver X Receptor (LXR) Signaling: A Potential Role for Lipid-Protein Adducts

When inhaled, ozone (O3) interacts with cholesterols of airway epithelial cell membranes or the lung-lining fluid, generating chemically reactive oxysterols. The mechanism by which O3-derived oxysterols affect molecular function is unknown. Our data show that in vitro exposure of human bronchial epithelial cells to O3 results in the formation of oxysterols, epoxycholesterol-α and -β and secosterol A and B (Seco A and Seco B), in cell lysates and apical washes. Similarly, bronchoalveolar lavage fluid obtained from human volunteers exposed to O3 contained elevated levels of these oxysterol species. As expected, O3-derived oxysterols have a pro-inflammatory effect and increase NF-κB activity. Interestingly, expression of the cholesterol efflux pump ATP-binding cassette transporter 1 (ABCA1), which is regulated by activation of the liver X receptor (LXR), was suppressed in epithelial cells exposed to O3. Additionally, exposure of LXR knock-out mice to O3 enhanced pro-inflammatory cytokine production in the lung, suggesting LXR inhibits O3-induced inflammation. Using alkynyl surrogates of O3-derived oxysterols, our data demonstrate adduction of LXR with Seco A. Similarly, supplementation of epithelial cells with alkynyl-tagged cholesterol followed by O3 exposure causes observable lipid-LXR adduct formation. Experiments using Seco A and the LXR agonist T0901317 (T09) showed reduced expression of ABCA1 as compared with stimulation with T0901317 alone, indicating that Seco A-LXR protein adduct formation inhibits LXR activation by traditional agonists. Overall, these data demonstrate that O3-derived oxysterols have pro-inflammatory functions and form lipid-protein adducts with LXR, thus leading to suppressed cholesterol regulatory gene expression and providing a biochemical mechanism mediating O3-derived formation of oxidized lipids in the airways and subsequent adverse health effects.

Iron decreases biological effects of ozone exposure.

Abstract Context: Ozone (O3) exposure is associated with a disruption of iron homeostasis and increased availability of this metal which potentially contributes to an oxidative stress and biological effects. Objective: We tested the postulate that increased concentrations of iron in cells, an animal model and human subjects would significantly impact the biological effects of O3 exposure. Results: Exposure to 0.4 ppm O3 for 5 h increased mRNA for both Superoxide Dismutase-1 (SOD1) and Cyclooxygenase-2 (COX2) in normal human bronchial epithelial (NHBE) cells. Pre-treatment of NHBE cells with 200 µM ferric ammonium citrate (FAC) for 4 h diminished changes in both SOD1 and COX2 following O3 exposure. mRNA transcript levels and associated protein release of the pro-inflammatory mediators IL-6 and IL-8 were increased by O3 exposure of NHBE cells; changes in these endpoints after O3 exposure were significantly decreased by FAC pre-treatment of the cells. Exposure of CD-1 mice to 2 ppm O3 for 3 h significantly increased lavage indices of inflammation and airflow limitation. Pre-treatment of the animals with pharyngeal aspiration of FAC diminished the same endpoints. Finally, the mean loss of pulmonary function in 19 healthy volunteers exposed to 0.3 ppm O3 for 2 h demonstrated significant correlations with either their pre-exposure plasma ferritin or iron concentrations. Discussion and conclusion: We conclude that greater availability of iron after O3 exposure does not augment biological effects. On the contrary, increased available iron decreases the biological effects of O3 exposure in cells, animals and humans.

Abstract 1731: Preclinical testing demonstrates strong activity of STA-12-8666, an HSP90 inhibitor-SN-38 conjugate, in small cell lung cancer (SCLC)

Purpose/Objectives: Small cell lung cancer (SCLC) is a highly aggressive disease representing 12-13% of all lung cancers, with 5 year survival rate of only 6%. While most patients respond initially to cytotoxic chemotherapies such as irinotecan, etoposide or carboplatin, resistance rapidly emerges and response to second line agents such as topotecan is limited, and in contrast to non-small cell lung cancer (NSCLC), few targetable oncogenes occur in SCLC. In this study, we tested new compound, STA-12-8666, which binds tumor-concentrated active form of shock protein 90 (HSP90) and has cleavable linker attached to SN-38, the active metabolite of irinotecan. Cleavage of the linker within the tumor provides time-release of SN-38 at high local concentration, while significantly limiting drug exposure and toxicity in non-transformed issue. The goal for this work was to evaluate STA-12-8666 for potential use as a new second line monotherapy, or as adjuvant in the frontline setting. Materials/Methods: Three dose levels of STA-12-8666 were evaluated in comparison to irinotecan, ganetespib, carboplatin, etoposide, and chemotherapy combinations in 4 independent SCLC xenograft models, including parental and cisplatin-resistant derivative cell lines (SCLC1, SR2), and a patient-derived xenograft (PDX). STA-12-8666 was also evaluated in drug combinations. Intratumoral responses were profiled using a mass spectrometry based approach to evaluate kinase pathway activation, and results confirmed by immunohistochemistry and western blot analysis. Pharmacokinetic analysis was performed to benchmark retention of STA-12-8666 to isomolar irinotecan in lung tumors. Results: In all three models, high dose (150 mg/kg) STA-12-8666 was well tolerated. In most cases, three doses administered at weekly intervals caused complete regression of established tumors, with response durable for > 2 months. Those tumors that regrew were responsive to re-dosing with STA-12-8666, and were subsequently eliminated. STA-12-8666 was also effective in limiting or eliminating tumors growth that had progressed following initial treatment on standard first and second line agents for SCLC. Low dose (50 mg/kg) STA-12-8666 controlled but did not eliminate tumors: however, it strongly enhanced the action of 30 mg/kg carboplatin, resulting in tumor elimination. Pharmacokinetic and proteomic analysis confirmed STA-12-8666 concentration in tumors, and identified a signature of DNA damage response biomarkers in STA-12-8666-treated tumors that strongly contrasted with the pattern induced by irinotecan. Conclusions: Together, these results indicate that STA-12-8666 may be a promising therapy in both frontline and second line settings for SCLC and strongly support the evaluation of this compound in Phase I/II clinical trials. Note: This abstract was not presented at the meeting. Citation Format: Anna Gaponova, AS Nikonova,A Deneka,BL Egleston,S Litwin,JS Duncan,K Duncan,H Borghaei,R Mehra,DA Proia,Y Boumber, Erica Golemis. Preclinical testing demonstrates strong activity of STA-12-8666, an HSP90 inhibitor-SN-38 conjugate, in small cell lung cancer (SCLC). [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 1731. doi:10.1158/1538-7445.AM2015-1731