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MicroRNAs (miRNAs) are small, non-protein-coding RNAs that can function as tumor suppressors or oncogenes. Deregulation of miRNA expression has been reported in lung cancer. However, modulation of miRNA expression by chemopreventive agents remains to be defined. In the present study, we examined if the chemopreventive agent indole-3-carbinol (I3C) reversed vinyl carbamate (VC)-induced deregulation of miRNA levels in lung tissues of female A/J mice. Lung tissues were obtained from a previous chemoprevention study, in which mice were treated with VC and given I3C in the diet for 15 weeks. Microarray studies revealed alterations in the expression of a number of miRNAs in lung tumors relative to that of normal lungs. miR-21, mir-31, miR-130a, miR-146b and miR-377 were consistently upregulated, whereas miR-1 and miR-143 were downregulated in lung tumors relative to normal lungs. In mice treated with VC and given I3C in the diet, levels of miR-21, mir-31, miR-130a, miR-146b and miR-377 were reduced relative to the level in mice treated with the carcinogen only. The results of the microarray study were confirmed by quantitative reverse transcription-polymerase chain reaction and gel analysis of polymerase chain reaction products. Further studies with miR-21 indicated that phosphatase and tensin homolog, programmed cell death 4 and rich protein with Kazal motifs are potential targets for the oncogenic effect of miR-21 and the chemopreventive activity of I3C. Taken together, we showed here that miRNAs are deregulated during VC-induced mouse lung tumorigenesis and their levels are modulated by I3C. Therefore, miRNAs and their target genes are promising biomarkers for the diagnosis of lung cancer and efficacy of chemopreventive/chemotherapeutic agents.

Key points• Exposure of human bronchial epithelial (HBE) cells to fungal aeroallergens derived from Alternaria alternata stimulates Ca 2+ -dependent and Ca 2+ -independent ATP release across the apical membrane.• The Ca 2+ -dependent component was blocked by inhibitors of both ATP uptake and transport of exocytotic vesicles to the plasma membrane.• Treatment with inhibitors that target cysteine proteases significantly blocked Ca 2+ -dependent ATP release evoked by Alternaria in normal HBE cells, but not in cells derived from asthmatic patients.• The magnitude of ATP release and associated intracellular Ca 2+ mobilization was significantly greater in bronchial epithelial cells obtained from patients with asthma.• These findings establish a novel role for ATP release as a mechanism underlying Alternaria aeroallergen activation of airway mucosal immunity and that cells derived from patients with asthma exhibit greater responsiveness to these allergens.Abstract Exposure of human bronchial epithelial (HBE) cells from normal and asthmatic subjects to extracts from Alternaria alternata evoked a rapid and sustained release of ATP with greater efficacy observed in epithelial cells from asthmatic patients. Previously, Alternaria allergens were shown to produce a sustained increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) that was dependent on the coordinated activation of specific purinergic receptor (P2Y 2 and P2X 7 ) subtypes. In the present study, pretreatment with a cell-permeable Ca 2+ -chelating compound (BAPTA-AM) significantly inhibited ATP release, indicating dependency on [Ca 2+ ] i . Alternaria-evoked ATP release exhibited a greater peak response and a slightly lower EC 50 value in cells obtained from asthmatic donors compared to normal control cells. Furthermore, the maximum increase in [Ca 2+ ] i resulting from Alternaria treatment was greater in cells from asthmatic patients compared to normal subjects. The vesicle transport inhibitor brefeldin A and BAPTA-AM significantly blocked Alternaria-stimulated incorporation of fluorescent lipid (FM1-43)-labelled vesicles into the plasma membrane and ATP release. In addition, inhibiting uptake of ATP into exocytotic vesicles with bafilomycin also reduced ATP release comparable to the effects of brefeldin A and BAPTA-AM. These results indicate that an important mechanism for Alternaria-induced ATP release is Ca 2+ dependent and involves exocytosis of ATP. Serine and cysteine protease inhibitors also reduced Alternaria-induced ATP release; however, the sustained increase in observed following Alternaria exposure appeared to be independent of protease-activated receptor (PAR2) stimulation.

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The association between pulmonary inflammation and lung cancer is well-established. However, currently there are no appropriate models that recapitulate inflammation-related lung cancer in humans. In the present study, we examined, in two tumor bioassays, enhancement by bacterial lipopolysaccharide (LPS) of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice. Mice that were treated with NNK alone developed 29.6 ± 9.8 and 36.2 ± 4.1 lung tumors/mouse in experiment 1 and 2, respectively. Chronic intranasal instillation of LPS to NNK-treated mice increased the multiplicity of lung tumors to 47.3 ± 16.1 and 51.2 ± 4.8 lung tumors/mouse in experiment 1 and 2, corresponding to a significant increase by 60% and 41%, respectively. Moreover, administration of LPS to NNK-pretreated mice significantly increased the multiplicity of larger tumors and histopathologically more advanced lesions (adenoma with dysplasia and adenocarcinoma), macrophage recruitment to the peritumoral area and expression of inflammation-, cell proliferation- and survival-related proteins. Overall, our findings demonstrated the promise of the NNK-LPS-A/J mice model to better understand inflammation-driven lung cancer, dissect the molecular pathways involved and identify more effective preventive and therapeutic agents against lung cancer.