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Cigarette smoke (CS) is a complex mixture of chemicals and interacts with various physiological processes. We previously reported that nuclear factor erythroid 2‐related factor 2 (NRF2) was the most sensitive transcription factor to aqueous CS extract (AqCSE) exposure in monolayer cultured human bronchial epithelial cell lines. Recently, in vitro three‐dimensional (3D) culture models have been used to supplement pharmacological and toxicological assessments. Bronchial epithelium models in particular are useful for the evaluation of substances that directly contact the respiratory tract, such as CS. In the present study, we used 3D‐cultured human bronchial epithelial cells (HBECs) to assess activation of transcription factors and relevant gene expression in response to AqCSE, primarily focusing on NRF2 and nuclear factor‐kappa B (NF‐κB) pathways. The 3D‐cultured HBECs exposed to AqCSE showed expression of NRF2 and its nuclear translocation in addition to upregulation of genes related to oxidative stress. Our results suggest that the NRF2 pathway was the dominant pathway when 3D‐cultured HBECs were exposed to AqCSE at a low dose, supporting our previous findings that NRF2 was the most sensitive transcription factor in response to AqCSE. Expression and nuclear translocation of NF‐κB were not increased, although proinflammatory genes were upregulated. However, another inflammation‐related transcription factor, activation protein 1, was induced by AqCSE. Gene classification analysis suggested that induction of the inflammatory response by AqCSE was dependent on NRF2 and activation protein 1 rather than NF‐κB. We assessed activation of transcription factors and relevant signaling pathways when human bronchial epithelial cells in three‐dimensional culture were exposed to aqueous cigarette smoke extract (AqCSE). Our results suggest that the nuclear factor erythroid 2‐related factor 2 (NRF2) pathway is the dominant pathway at low‐dose exposure, supporting our previous findings that NRF2 is the most sensitive transcription factor to AqCSE. Moreover, the AqCSE‐induced inflammatory response is dependent on NRF2 and activation protein 1 rather than nuclear factor‐kappa B. [ABSTRACT FROM AUTHOR]

Radiolabeled antibodies, polyethylene glycol-conjugated (PEGylated) peptides, liposomes, and other materials were investigated as positron-emission tomography (PET) probes. These substances accumulate in tumors but often remain too long in circulation. We investigated the combination of intravenous urokinase injection and its substrate linker as a triggered radioisotope clearance enhancement system to improve imaging contrast. To this end, we synthesized a four-arm PEGylated 64 Cu-bombesin analog tetramer with a urokinase substrate linker. In mouse blood, it was almost perfectly cleaved and degraded into smaller radioactive fragments in vitro with urokinase (≥20,000 IU/mL). In mouse blood circulation, ∼50-65% of the probe was rapidly degraded after the urokinase injection and the radioactive fragments were eliminated mainly from the kidney. In contrast, tumor radioactivity levels did not change, and therefore, the tumors were clearly visualized. The tumor/blood ratio, an indicator of imaging contrast, increased 2.5 times, while elimination of the radioisotope from the blood was enhanced. This approach has the potential to improve imaging contrast using various PET probes. It could also shorten the time required to obtain sufficient contrast and decrease patient radiation exposure., (Copyright © 2018 Elsevier B.V. All rights reserved.)