Unlocking Structurally Nontraditional Naphthyridine-Based Electron-Transporting Materials with C-H Activation-Annulation.

The inherent benefits of C-H activation have given rise to innovative approaches in designing organic optoelectronic molecules that depart from conventional methods. While theoretical calculations have suggested the suitability of the 2,6-naphthyridine scaffold for electron transport materials (ETMs) in organic light-emitting diodes (OLEDs), the existing synthetic methodologies have proven to be insufficient for the construction of multiple arylated and fully aryl-substituted molecules. Herein, we present a solution for the synthesis of 2,6-naphthyridine derivatives, with the rhodium-catalyzed consecutive C-H activation-annulation process of fumaric acid with alkynes standing as the pivotal step within this strategy. The ETMs, purposefully designed and synthesized based on the 2,6-naphthyridine framework, exhibit an impressively high glass-transition temperature (Tg) of 282 °C and high electron mobility (µe), setting a new benchmark for ETMs in OLEDs with a µe exceeding 10-2 cm2 V-1 s-1. These materials prove to be versatile ETM candidates suitable for red, green, and blue phosphorescent OLED devices.

Aberrant activation of AXL may drive progression of squamous cell carcinoma in CLL patients: a mechanistic study with clinical implications.

BACKGROUND: Occurrence of squamous cell carcinoma (SCC) even in early-stage, untreated chronic lymphocytic leukemia (CLL) patients can be a significant morbidity issue with occasional transformation into metastatic skin lesions. METHODS: CLL cells and extracellular vesicles (EVs) from CLL patients' blood/plasma were purified and used. Expression/activation of AXL and its functions in normal keratinocytes (HEKa) were assessed in vitro co-culture system and in SCC tissues. RESULTS: We detected aberrant activation of AXL, AKT and ERK-1/2 in SCC cell lines compared to HEKa. We also detected increased expression of AXL in primary SCC tissues obtained from CLL patients. Increased activation of AXL, AKT, ERK-1/2 and Src was discernible in HEKa upon co-culturing with CLL cells. Further analysis suggests that Gas6, a ligand of AXL, regulates AXL activation in co-cultured HEKa. Interestingly, exposure of HEKa cells to CLL plasma-derived EVs induced expression of AXL, P-AKT, and EMT-associated markers leading to migration of the cells. Finally, pharmacologic inhibition of AXL induced cell death in SCC lines in a dose dependent manner. CONCLUSIONS: Our findings that CLL cells likely are involved in driving SCC progression, at least in part, via activation of the AXL signaling axis, indicating that AXL inhibition may be beneficial for our CLL patients with SCC.

Deletion of a 7-amino-acid region in the porcine epidemic diarrhea virus envelope protein induces higher type I and III interferon responses and results in attenuation in vivo.

Porcine epidemic diarrhea virus (PEDV) leads to enormous economic losses for the pork industry. However, the commercial vaccines failed to fully protect against the epidemic strains. Previously, the rCH/SX/2016-SHNXP strain with the entire E protein and the rCH/SX/2015 strain with the deletion of 7-amino-acid (7-aa) at positions 23-29 in E protein were constructed and rescued. The pathogenicity assay indicated that rCH/SX/2015 is an attenuated strain, but rCH/SX/2016-SHNXP belongs to the virulent strains. Then, the recombination PEDV (rPEDV-EΔaa23-aa29)strain with a 7-aa deletion in the E protein was generated, using the highly virulent rCH/SX/2016-SHNXP strain (rPEDV-Ewt) as the backbone. Compared with the rPEDV-Ewt strain, the release and infectivity of the rPEDV-EΔaa23-aa29 strain were significantly reduced in vitro, but stronger interferon (IFN) responses were triggered both in vitro and in vivo. The pathogenicity assay showed that the parental strain resulted in severe diarrhea (100%) and death (100%) in all piglets. Compared with the parental strain group, rPEDV-EΔaa23-aa29 caused lower mortality (33%) and diminished fecal PEDV RNA shedding. At 21 days, all surviving pigs were challenged orally with rPEDV-Ewt. No pigs died in the two groups. Compared with the mock group, significantly delayed and milder diarrhea and reduced fecal PEDV RNA shedding were detected in the rPEDV-EΔaa23-aa29 group. In conclusion, the deletion of a 7-aa fragment in the E protein (EΔaa23-aa29) attenuated PEDV but retained its immunogenicity, which can offer new ideas for the design of live attenuated vaccines and provide new insights into the attenuated mechanism of PEDV. IMPORTANCE Porcine epidemic diarrhea virus (PEDV) causes high mortality in neonatal piglets and remains a large challenge to the pork industry. Unfortunately, no safe and effective vaccines are available yet. The pathogenesis and molecular basis of the attenuation of PEDV remain unclear, which seriously hinders the development of PEDV vaccines. This study found that the rPEDV carrying EΔaa23-aa29 mutation in the E protein induced significantly higher IFN responses than the parental virus, partially attenuated, and remained immunogenic in piglets. For the first time, PEDV E was verified as an IFN antagonist in the infection context and identified as a virulence factor of PEDV. Our data also suggested that EΔaa23-aa29 mutation can be a good target for the development of live attenuated vaccines for PEDV and also provide new perspectives for the attenuated mechanism of PEDV.

Enantiomeric Fractions Reveal Differences in the Atropselective Disposition of 2,2',3,5',6-Pentachlorobiphenyl (PCB 95) in Wildtype, Cyp2abfgs-Null, and CYP2A6-Humanized Mice.

Polychlorinated biphenyls (PCBs) are environmental contaminants that can cause neurotoxicity. PCBs, such as PCB 95 (2,2',3,5',6-pentachlorobiphenyl), can be metabolized by cytochrome P450 enzymes into neurotoxic metabolites. To better understand how the metabolism of PCB 95 affects neurotoxic outcomes, we conducted a study on the disposition of PCB 95 in transgenic mouse models. The mice were given a single oral dose of PCB 95 (1.0 mg/kg) and were euthanized 24 h later for analysis. PCB 95 levels were highest in adipose tissue, followed by the liver, brain, and blood. Adipose tissue levels were significantly higher in wild-type (WT) mice than in Cyp2abfgs-null (KO) or CYP2A6-transgenic (KI) mice. We also observed genotype-dependent differences in the enrichment of aS-PCB 95 in female mice, with a less pronounced enrichment in KO than WT and KI mice. Ten hydroxylated PCB 95 metabolites were detected in blood and tissue across all exposure groups. The metabolite profiles differed across tissues, while sex and genotype-dependent differences were less pronounced. Total OH-PCB levels were highest in the blood, followed by the liver, adipose tissue, and brain. Total OH-PCB blood levels were lower in KO than in WT mice, while the opposite trend was observed in the liver. In male mice, total OH-PCB metabolite levels were significantly lower in KI than in WT mice in blood and the liver, while the opposite trend was observed in female mice. In conclusion, the study highlights the differences in the atropselective disposition of PCB 95 and its metabolites in different types of mice, demonstrating the usefulness of these transgenic mouse models for characterizing the role of PCB metabolism in PCB neurotoxicity.

Molecular Engineering of Chalcogen-Embedded Anthanthrenes via peri-Selective C-H Activation: Fine-Tuning of Crystal Packing for Organic Field-Effect Transistors.

Disclosed herein is a RhCl3 -catalyzed peri-selective C-H/C-H oxidative homo-coupling of 1-substituted naphthalenes, which provides a highly efficient and streamlined approach to chalcogen-embedded anthanthrenes from readily available starting materials. Introducing O, S, and Se into the anthanthrene skeleton leads to gradually increased π-π stacking distances but significantly enhanced π-π overlaps with the growth of the hetero-atom radius. Moderate π-π distance, overlap area, and intermolecular S-S interactions endow S-embedded anthanthrene (PTT) with excellent 2D charge-transport properties. Moreover, the transformation of p-type to n-type S-embedded anthanthrenes is realized for the first time via the S-atom oxidation from PTT to PTT-O4. In organic field-effect transistor devices, PTT derivatives exhibit hole transport with mobilities up to 1.1 cm2  V-1 s-1 , while PTT-O4 shows electron transport with a mobility of 0.022 cm2  V-1 s-1 .

Alignment of Heptagonal Diimide and Triazine Enables Narrowband Pure-Blue Organic Light-Emitting Diodes with Low Efficiency Roll-Off.

The endeavor to develop high-performance narrowband blue organic light-emitting diodes (OLEDs) with low efficiency roll-off represents an attractive challenge. Herein, we introduce a hetero-acceptor design strategy centered around the heptagonal diimide (BPI) building block to create an efficient thermally activated delayed fluorescence (TADF) sensitizer. The alignment of a twisted BPI unit and a planar diphenyltriazine (TRZ) fragment imparts remarkable exciton dynamic properties to 26tCz-TRZBPI, including a fast radiative decay rate (kR ) of 1.0×107  s-1 and a swift reverse intersystem crossing rate (kRISC ) of 1.8×106  s-1 , complemented by a slow non-radiative decay rate (kNR ) of 6.0×103  s-1 . Consequently, 26tCz-TRZBPI facilitates the fabrication of high-performance narrowband pure-blue TADF-sensitized fluorescence OLEDs (TSF-OLEDs) with a maximum external quantum efficiency (EQEmax ) of 24.3 % and low efficiency roll-off even at a high brightness level of 10000 cd m-2 (EQE10000 : 16.8 %). This showcases a record-breaking external quantum efficiency at a high luminance level of 10000 cd m-2 for narrowband blue TSF-OLEDs.

Genetic characterization and pathogenicity of a novel recombinant PRRSV from lineage 1, 8 and 3 in China failed to infect MARC-145 cells.

The diversity of porcine reproductive and respiratory syndrome virus (PRRSV) in China is increasing rapidly along with mutation and recombination. Recombination could occur between inter- and intra-lineage of PRRSV, which accelerated the complexity of pathogenicity and cell tropism of the recombinant strain. In the present study, a novel PRRSV strain named HN-YL1711 was isolated from a pig farm suffering from severe respiratory difficulty in Henan province, China. The whole genomic sequence analysis indicated that the genome of HN-YL1711 was 15018 nt. It shared 86%, 87.3%, 88.1%, 91.1%, 84.2%, and 84.1% nucleotide similarities with PRRSVs VR2332, CH1a, JXA1, NADC30, QYYZ, and GM2, respectively. Based on phylogenetic analysis of Nsp2, ORF5 and complete genomes, HN-YL1711 was classified into lineage 1 of PRRSV. However, seven genomic break points were detected in recombination analysis, which indicated that the HN-YL1711 originated from multiple recombination among NADC30-like (major parent, lineage 1), JXA1-like (minor parent, lineage 8), and QYYZ-like (minor parent, lineage 3) PRRSV. Porcine alveolar macrophages (PAMs), 3D4/21-CD163 and MARC-145 cells were used to explore the viral adaptation of HN-YL1711. The results indicated that it could infect the PAMs but failed to infect MARC-145 cells. Challenge experiments showed that HN-YL1711 exhibits intermediate virulence in pigs, compared with HP-PRRSV JXA1 and LP-PRRSV CH1a. Taken together, our findings suggest that recombination remains an important factor in PRRSV evolution and that recombination further complicates the cell tropism and pathogenicity of PRRSV.

Intramolecular C-H Activation as an Easy Toolbox to Synthesize Pyridine-Fused Bipolar Hosts for Blue Organic Light-Emitting Diodes.

The development of high-performance blue organic light-emitting diodes (OLEDs) remains a challenging task. While exploiting new blue emitters has attracted great interest, developing host materials that considerably determine device performance obviously lags behind. Herein, we present an ease of access to the structurally diverse benzoheteroaromatic-fused pyridine skeletons by the iridium-catalyzed intramolecular C-H/C-H coupling reaction, which unlocks an unparalleled opportunity to rapidly assemble a library of pyridine-fused bipolar host materials. As an illustrated example, the benzo[4,5]thieno[2,3-b]pyridine skeleton (BTP) has been made to a pseudo-symmetric host (DCz-BTP). The merging of a pyridine fragment enables strong intermolecular interactions, leading to satisfactory bipolar transporting properties. Utilizing DCz-BTP as the host, blue thermally activated delayed fluorescent OLEDs (TADF-OLEDs) exhibit a low turn-on voltage of 2.8 V and a high maximum external quantum efficiency (EQEmax ) of 29.0 % and blue TADF-sensitized florescent OLEDs (TSF-OLEDs) give an EQEmax as high as 20.5 %, revealing the potential of the BTP skeleton for the construction of high-performance host materials.

Structurally Nontraditional Benzo[c]cinnoline-Based Electron-Transporting Materials with 3D Molecular Interaction Architecture.

The academically widely used electron-transporting materials (ETMs) typically suffer from low glass transition temperatures (Tg ) that could lead to poor device stability. Considering practical applications, we herein put forward a "3D molecular interaction architecture" strategy to design high-performance ETMs. As a proof-of-concept, a type of structurally nontraditional ETMs with the benzo[c]cinnoline (BZC) skeleton have been proposed and synthesized by the C-H/C-H homo-coupling of N-acylaniline as the key step. 2,9-diphenylbenzo[c]cinnoline (DPBZC) exhibits strong intermolecular interactions that feature a 3D architecture, which boosts Tg to exceedingly high 218 °C with a fast electron mobility (µe ) of 6.4×10-4  cm2 V-1 s-1 . DPBZC-based fluorescent organic light-emitting diodes show outstanding electroluminescent performances with an external quantum efficiency of 20.1 % and a power efficiency as high as 70.6 lm W-1 , which are superior to those of the devices with the commonly used ETMs.

Cascade Oxidative C-H Annulation of Thiophenes: Heck-Type Pathway Enables Concise Access to Thienoacenes.

The pursuit of efficient synthetic route to thienoacenes represents an appealing yet challenging task in the fields of both organic synthetic chemistry and organic functional materials. In this work, we disclose a rhodium-catalyzed cascade C-H annulation of phenacyl phosphoniums with (benzo)thiophenes via a Heck-type pathway to provide a new class of planar thienoacenes, which involves the formation of three Caryl -Caryl bonds and one Caryl -O bond in a single operation. The neutral S,O-heteroacenes exhibit superior stability and adopt a herringbone-like packing mode with efficient π-π stacking in the crystals, suggesting their potential in organic semiconducting materials. This work first exemplifies the superiority of cascade oxidative C-H annulation involving a Heck-type pathway in the development of concise access to heteroacenes.

GLI2-Mediated Inflammation in the Tumor Microenvironment.

The tumor microenvironment (TME) plays an important role in the development and progression of cancer and has been shown to contribute to resistance to therapy. Inflammation is one of the hallmarks of cancer implicated in disease phenotype. Therefore, understanding the mechanisms that regulate inflammation in cancer and consequently how inflammatory mediators promote cancer progression is important for our understanding of cancer cell biology. The transcription factor GLI2 was initially identified as a member of the Hedgehog (HH) signaling pathway. During the last decade, studies have shown a novel mechanism of GLI2 regulation independent of HH signaling, where GLI2 consequently modulated several cytokine genes in the TME. These studies highlight a novel role for GLI2 as an inflammatory mediatory independent of HH stimulation. This chapter will discuss canonical and noncanonical pathways of GLI2 regulation and some of the downstream cytokine target genes regulated by GLI2.

Double ortho-C-H Activation/Annulation of Benzamides with Aryl Alkynes: A Route to Double-Helical Polycyclic Heteroaromatics.

It remains a challenge to achieve N,O-double annulations of primary benzamides with aryl alkynes due to competitive N,N-double annulations. Herein, we employed sterically hindered 1-methylcyclohexane-1-carboxylic acid to address this challenge, the double ortho-C-H activation of benzamides and subsequent N,O-double annulations with aryl alkynes have been accomplished for the first time. The resulting product can be further transformed into a double-helical extended π-conjugated polycyclic heteroarene via Scholl oxidation, which exhibits blue emission with high fluorescence quantum yields.

Novel Molecular Mechanism of Regulation of CD40 Ligand by the Transcription Factor GLI2.

The interaction between tumor cells and their surrounding microenvironment is essential for the growth and persistence of cancer cells. This interaction is mediated, in part, by cytokines. Although the role of cytokines in normal and malignant cell biology is well established, many of the molecular mechanisms regulating their expression remain elusive. In this article, we provide evidence of a novel pathway controlling the transcriptional activation of CD40L in bone marrow-derived stromal cells. Using a PCR-based screening of cytokines known to play a role in the biology of bone marrow malignancies, we identified CD40L as a novel GLI2 target gene in stromal cells. CD40L plays an important role in malignant B cell biology, and we found increased Erk phosphorylation and cell growth in malignant B cells cocultured with CD40L-expressing stromal cells. Further analysis indicated that GLI2 overexpression induced increased CD40L expression, and, conversely, GLI2 knockdown reduced CD40L expression. Using luciferase and chromatin immunoprecipitation assays, we demonstrate that GLI2 directly binds and regulates the activity of the CD40L promoter. We found that the CCR3-PI3K-AKT signaling modulates the GLI2-CD40L axis, and GLI2 is required for CCR3-PI3K-AKT-mediated regulation of the CD40L promoter. Finally, coculture of malignant B cells with cells stably expressing human CD40L results in increased Erk phosphorylation and increased malignant B cell growth, indicating that CD40L in the tumor microenvironment promotes malignant B cell activation. Therefore, our studies identify a novel molecular mechanism of regulation of CD40L by the transcription factor GLI2 in the tumor microenvironment downstream of CCR3 signaling.

P450-Humanized and Human Liver Chimeric Mouse Models for Studying Xenobiotic Metabolism and Toxicity.

Preclinical evaluation of drug candidates in experimental animal models is an essential step in drug development. Humanized mouse models have emerged as a promising alternative to traditional animal models. The purpose of this mini-review is to provide a brief survey of currently available mouse models for studying human xenobiotic metabolism. Here, we describe both genetic humanization and human liver chimeric mouse models, focusing on the advantages and limitations while outlining their key features and applications. Although this field of biomedical science is relatively young, these humanized mouse models have the potential to transform preclinical drug testing and eventually lead to a more cost-effective and rapid development of new therapies.

Modulation of the IL-6 Receptor α Underlies GLI2-Mediated Regulation of Ig Secretion in Waldenström Macroglobulinemia Cells.

Ig secretion by terminally differentiated B cells is an important component of the immune response to foreign pathogens. Its overproduction is a defining characteristic of several B cell malignancies, including Waldenström macroglobulinemia (WM), where elevated IgM is associated with significant morbidity and poor prognosis. Therefore, the identification and characterization of the mechanisms controlling Ig secretion are of great importance for the development of future therapeutic approaches for this disease. In this study, we define a novel pathway involving the oncogenic transcription factor GLI2 modulating IgM secretion by WM malignant cells. Pharmacological and genetic inhibition of GLI2 in WM malignant cells resulted in a reduction in IgM secretion. Screening for a mechanism identified the IL-6Rα (gp80) subunit as a downstream target of GLI2 mediating the regulation of IgM secretion. Using a combination of expression, luciferase, and chromatin immunoprecipitation assays we demonstrate that GLI2 binds to the IL-6Rα promoter and regulates its activity as well as the expression of this receptor. Additionally, we were able to rescue the reduction in IgM secretion in the GLI2 knockdown group by overexpressing IL-6Rα, thus defining the functional significance of this receptor in GLI2-mediated regulation of IgM secretion. Interestingly, this occurred independent of Hedgehog signaling, a known regulator of GLI2, as manipulation of Hedgehog had no effect on IgM secretion. Given the poor prognosis associated with elevated IgM in WM patients, components of this new signaling axis could be important therapeutic targets.

Lung cancer transcriptomes refined with laser capture microdissection.

We evaluated the importance of tumor cell selection for generating gene signatures in non-small cell lung cancer. Tumor and nontumor tissue from macroscopically dissected (Macro) surgical specimens (31 pairs from 32 subjects) was homogenized, extracted, amplified, and hybridized to microarrays. Adjacent scout sections were histologically mapped; sets of approximately 1000 tumor cells and nontumor cells (alveolar or bronchial) were procured by laser capture microdissection (LCM). Within histological strata, LCM and Macro specimens exhibited approximately 67% to 80% nonoverlap in differentially expressed (DE) genes. In a representative subset, LCM uniquely identified 300 DE genes in tumor versus nontumor specimens, largely attributable to cell selection; 382 DE genes were common to Macro, Macro with preamplification, and LCM platforms. RT-qPCR validation in a 33-gene subset was confirmatory (ρ = 0.789 to 0.964, P = 0.0013 to 0.0028). Pathway analysis of LCM data suggested alterations in known cancer pathways (cell growth, death, movement, cycle, and signaling components), among others (eg, immune, inflammatory). A unique nine-gene LCM signature had higher tumor-nontumor discriminatory accuracy (100%) than the corresponding Macro signature (87%). Comparison with Cancer Genome Atlas data sets (based on homogenized Macro tissue) revealed both substantial overlap and important differences from LCM specimen results. Thus, cell selection via LCM enhances expression profiling precision, and confirms both known and under-appreciated lung cancer genes and pathways.

A quantitative method to identify microRNAs targeting a messenger RNA using a 3'UTR RNA affinity technique.

The identification of specific microRNAs (miRNAs) that target a given messenger RNA (mRNA) is essential for studies in gene regulation, but the available bioinformatic software programs are often unreliable. We have developed a unique experimental miRNA affinity assay whereby a 3'UTR RNA is end-labeled with biotin, immobilized, and then used as a bait sequence for affinity pull-down of miRNAs. After washes and release, cloning and sequencing identify the miRNAs. Binding affinity is quantitated by quantitative polymerase chain reaction (qPCR), comparing released and original input concentrations. As an initial demonstration, the TCF8/ZEB1 mRNA affinity pull-down yielded miR-200 family member miRs in the majority of clones, and binding affinity was approximately 100%; virtually all copies of miR-200c bound the immobilized mRNA transcript. For validation in cells, miR-200c strongly inhibited expression of a TCF8 luciferase reporter, native TCF8 mRNA, and protein levels, which contrasted with other recovered miRNAs with lower binding affinities. For Smad4 mRNA, miR-150 (and others) displayed a binding affinity of 39% (or less) yet did not inhibit a Smad4 reporter, native Smad4 mRNA, or protein levels. These results were not predicted by available software. This work demonstrates this miRNA binding affinity assay to be a novel yet facile experimental means of identification of miRNAs targeting a given mRNA.

Initial development and testing of an exhaled microRNA detection strategy for lung cancer case-control discrimination.

For detecting field carcinogenesis non-invasively, early technical development and case-control testing of exhaled breath condensate microRNAs was performed. In design, human lung tissue microRNA-seq discovery was reconciled with TCGA and published tumor-discriminant microRNAs, yielding a panel of 24 upregulated microRNAs. The airway origin of exhaled microRNAs was topographically "fingerprinted", using paired EBC, upper and lower airway donor sample sets. A clinic-based case-control study (166 NSCLC cases, 185 controls) was interrogated with the microRNA panel by qualitative RT-PCR. Data were analyzed by logistic regression (LR), and by random-forest (RF) models. Feasibility testing of exhaled microRNA detection, including optimized whole EBC extraction, and RT and qualitative PCR method evaluation, was performed. For sensitivity in this low template setting, intercalating dye-based URT-PCR was superior to fluorescent probe-based PCR (TaqMan). In application, adjusted logistic regression models identified exhaled miR-21, 33b, 212 as overall case-control discriminant. RF analysis of combined clinical + microRNA models showed modest added discrimination capacity (1.1-2.5%) beyond clinical models alone: all subjects 1.1% (p = 8.7e-04)); former smokers 2.5% (p = 3.6e-05); early stage 1.2% (p = 9.0e-03), yielding combined ROC AUC ranging from 0.74 to 0.83. We conclude that exhaled microRNAs are qualitatively measureable, reflect in part lower airway signatures; and when further refined/quantitated, can potentially help to improve lung cancer risk assessment.

High-throughput library screening identifies two novel NQO1 inducers in human lung cells.

Many phytochemicals possess antioxidant and cancer-preventive properties, some putatively through antioxidant response element-mediated phase II metabolism, entailing mutagen/oxidant quenching. In our recent studies, however, most candidate phytochemical agents were not potent in inducing phase II genes in normal human lung cells. In this study, we applied a messenger RNA (mRNA)-specific gene expression-based high throughput in vitro screening approach to discover new, potent plant-derived phase II inducing chemopreventive agents. Primary normal human bronchial epithelial (NHBE) cells and immortalized human bronchial epithelial cells (HBECs) were exposed to 800 individual compounds in the MicroSource Natural Products Library. At a level achievable in humans by diet (1.0 µM), 2,3-dihydroxy-4-methoxy-4'-ethoxybenzophenone (DMEBP), triacetylresveratrol (TRES), ivermectin, sanguinarine sulfate, and daunorubicin induced reduced nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase 1 (NQO1) mRNA and protein expression in NHBE cells. DMEBP and TRES were the most attractive agents as coupling potency and low toxicity for induction of NQO1 (mRNA level, ≥3- to 10.8-fold that of control; protein level, ≥ two- to fourfold that of control). Induction of glutathione S-transferase pi mRNA expression was modest, and none was apparent for glutathione S-transferase pi protein expression. Measurements of reactive oxygen species and glutathione/oxidized glutathione ratio showed an antioxidant effect for DMEBP, but no definite effect was found for TRES in NHBE cells. Exposure of NHBE cells to H(2)O(2) induced nuclear translocation of nuclear factor erythroid 2-related factor 2, but this translocation was not significantly inhibited by TRES and DMEBP. These studies show that potency and low toxicity may align for two potential NQO1-inducing agents, DMEBP and TRES.