* Institute of Toxicology and Department of Internal Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC, and
Division of Environmental Health and Occupational Medicine, National Health Research Institute, Kaohsiung, Taiwan, ROC
1 To whom correspondence should be addressed at Institute of Toxicology, College of Medicine, National Taiwan University, 1 Jen Ai Road, Section 1, Taipei, Taiwan, ROC. Fax: 886223140217. E-mail: thueng{at}ha.mc.ntu.edu.tw.
Received March 22, 2005; accepted June 23, 2005
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ABSTRACT |
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Key Words: motorcycle exhaust particulate; benzo(a)pyrene; fibrobalst growth factor; interleukin; lung epithelial cell.
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INTRODUCTION |
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ME and MEP have many toxicological properties. For example, ME inhalation exposure increased lipid peroxidation and decreased cytochrome P450 (CYP) 2B1 protein in rat lung (Ueng et al., 2004). Treatment of human lung cancer cells with organic extracts of MEP increased oxidative stress and DNA damage and decreased gap junctional intercellular communication (Kuo et al., 1998
). Furthermore, MEP extract was found to enhance vasoconstriction in organ culture of rat aortas and induce inflammation and hyperresponsiveness in mouse airways (Lee et al., 2004
; Tzeng et al., 2003
).
Airway epithelium is a physical barrier to inhaled particulates and toxicants and a critical cell type in the pathogenesis of lung disease and cancer. The lung epithelial cells are responsive to the stimulatory effects of diesel exhaust particulates (DEP), which induce production of cytokines and mediators in human bronchial epithelial cells (Kawasaki et al., 2001; Steerenberg et al., 1998
). Induction of these inflammatory mediators is believed to be one of the etiological factors for asthma and chronic obstructive pulmonary disease (Mills et al., 1999
). Information regarding the effect of MEP on cytokine production by lung epithelium remains to be explored. Airway epithelium is a target site of cancers such as lung adenocarcinoma, which has a high female-to-male ratio and a large proportion of nonsmokers. Gene and environment interactions could possibly contribute to the high female susceptibility to lung adenocarcinoma. CYP enzymes are involved in activation of pulmonary PAH carcinogens and mammary carcinogen 17ß-estradiol. MEP induced CYP1A1 and CYP1B1 expression in CL5 female lung epithelial adenocarcinoma cell line (Wang et al., 2002
). Oncogene, tumor suppressor, and estrogen signaling genes may play significant roles in female lung carcinogenesis. MEP interactions with these genes still need to be elucidated.
The major objective of our studies was to investigate the interaction of MEP with genes important in the development of lung disease and cancer in human lung epithelial cells. In this regard, CL5 cells were treated with MEP extracts, and cDNA microarrays analyses were conducted using arrays consisting of 255 genes selected from the metabolic enzyme, cytokine, oncogene, tumor suppressor, and estrogen signaling families. Gene alteration and bioactivity studies were extended to include the prototypic chemical carcinogen benzo(a)pyrene, for mechanistic and comparison purposes.
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MATERIALS AND METHODS |
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Gas chromatography/mass spectrometry (GC/MS) analysis of MEP extract.
The MEP extract was analyzed for PAH using a Hewlett-Packard 6890 gas chromatograph and a 5973 mass spectrometer equipped with a 7673 autosampler and an HP-5MS capillary column (60 m x 0.25 mm ID, 0.25 µm film thickness). The GC/MS operation conditions were as described previously (Ueng et al., 2000). Helium was used as the GC carrier gas. Following sample injection, the GC column was held at 80°C for 0.1 min, temperature programmed to 190°C at 10°C/min, 260°C at 3.5°C/min, and 300°C at 1.4°C/min. The MS was operated under 280°C detector temperature at 70 eV in the scan and selected ion models for qualitative and quantitative analyses, respectively. The GC column was calibrated with a standard U.S. Environmental Protection Agency 610 Polynuclear Aromatic Hydrocarbons Mixture consisting of 16 priority PAH pollutants (Supelco, Inc., Bellefonte, PA). Each PAH of MEP extract was quantified by means of an external calibration curve built from standard PAH solutions of 2, 5, 10, and 50 µg/ml. If the target PAH analyte exceeded the linear range of the calibration standards, the MEP extract sample was further diluted and reanalyzed.
Cells and treatments.
The human lung epithelium cell line CL5 was derived from a lung adenocarcinoma tumor specimen of a 40-year-old women patient at the Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan. The cell line has been single-cell cloned and maintained in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM L-glutamine, 100 IU/ml penicillin, 100 µg/ml streptomycin, and 2.0 g/l sodium bicarbonate at 37°C in a humidified atmosphere of 5% CO2. Human bronchial epithelial BEAS-2B cells immortalized with SV40 (American Type Culture Collection, Manassas, VA) were gifts from Dr. Pinpin Lin, Institute of Toxicology, Chung Shan Medical University, Taichung, Taiwan. BEAS-2B cells were maintained in serum-free LHC-9 medium with glutamine (BioSource International Inc., Rockville, MD). WI-38 human normal lung fibroblast (American Type Culture Collection) was obtained from Food Industry Research and Development Institute, Hsinchu, Taiwan. WI-38 cells were maintained in minimum essential medium (MEM) supplemented with 10% fetal bovine serum, 2 mM L-glutamine, 0.1 mM nonessential amino acids, 1.0 mM sodium pyruvate, and 1.5 g/l sodium bicarbonate.
Lung cells were used when the monolayer reached near confluence. The cell density was about 10 x 106 cells/dish in 10-cm culture dishes for treatment. MEP extract or test compound was dissolved in dimethyl sulfoxide (DMSO) and added to the medium so that DMSO concentration in the medium was less than 0.1%. Control cells were treated with 0.1% DMSO in medium. Cell viability was determined using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) (Carmichael et al., 1987). Peroxide formation was determined using the oxidation-sensitive probe 2',7'-dichlorofluorescin diacetate (DCFH-DA) (Lebel et al., 1992
).
cDNA probe preparation and cDNA microarray analysis.
Gene expression profile was analyzed using nonradioactive GEArray pathway-specific expression arrays (SuperArray Inc., Bethesda, MD). The five arrays used were the human drug metabolism and common cytokine gene arrays, consisting of 96 genes each, and the human cancer/oncogene, cancer/tumor suppressor, and estrogen signaling pathway arrays, each consisting of 23 genes. There were cDNA fragments of 255 individual genes on these nylon-membrane arrays, and their gene tables are available (www.superarray.com). Total RNA was isolated from CL5 cells as described previously (Wang et al., 2001) and converted to biotinylated cDNA probes by reverse transcription with a dNTP mix containing biotin-dUTP. Biotinylated cDNA probes were hybridized to gene-specific cDNA fragments spotted on the membranes following manufacture's protocol. The GEArray membrane was then blocked with GEAblocking solution and incubated with alkaline phosphatase conjugated streptavidin. The relative gene expression levels were detected by chemiluminescence signal using the alkaline phosphatase substrate, CDP-Star, and X-ray film. The relative abundance of a particular transcript was estimated by comparing its signal intensity to the signals derived from internal hybridization controls ß-actin and GAPDH. Image analysis and spot quantitation were carried out using GenePix 3.0 program (Axon Instruments, Union City, CA).
Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis.
Five µg total RNA were reverse transcribed using 1X RT, 2.2 mM MgCl2, 2.0 mM dNTP, 0.2 U/ml RNAsin, 0.5 mM random hexamer primers, and 0.3 U/µl MMLV reverse transcriptase in 25 µl reactions using a 2-step cycle: 70°C, 5 min and 37°C, 2 h. Reverse transcription reagents were purchased from Promega Corp., Madison, WI. The resulting cDNA was used in subsequent real-time RT-PCR reactions with fluorescence detection using an ABI Prism 7700 Sequence Detection System (Applied Biosystems, Foster City, CA). Reaction was carried out in microAmp 96-well reaction plates, SYBR Green PCR Master Mix 2X, DNA polymerase, dNTPs with dUTP, forward and reverse primers (0.15 µM each) (Invitrogen Corp., Carlsbad, CA), and 200 ng cDNA in a final volume of 25 µl. Amplification parameters were: denaturation at 94°C 10 min, followed by 45 cycles of 95°C, 15 s; 60°C, 60 s. All primers and probes were designed using PrimerExpress software (Table 1). Samples were analyzed in triplicate, and ß-actin was used as an endogenous control.
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RT-PCR analysis.
Two µg total RNA were isolated from CL5, BEAS-2B cells, or rat lung. cDNA synthesis and PCR were conducted as described previously (Wang et al., 2001). PCR primers for CYPs, cytokines, and internal controls were synthesized (Gibco/BRL, Life Technologies, Inc., Gaithersburg, MD) according to the published sequences (Table 2). All reactions were conducted with ß-actin or cyclophilin primers as internal controls. PCR products were separated on 2% agarose gels and stained with ethidium bromide. Intensity of PCR product was quantitated using an IS-1000 Digital Imaging System (Alpha Innotech Corporation, San Leandro, CA) and normalized against the intensity of internal control ß-actin or cyclophilin. Relative intensity of target gene PCR product from treated cell culture or rats was calculated by dividing its intensity by the corresponding intensity from control cells or rats.
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Enzyme-linked immunosorbent assay (ELISA).
CL5 cells in maintenance medium were plated at 1 x 105 cells per well in 6-well tissue culture plates. After seeding overnight, maintenance medium was changed to experimental medium consisting of RPMI 1640 medium supplemented with 1% charcoal-treated fetal calf serum. After 12 h incubation, the medium was removed, and 1 ml fresh experimental medium containing 100 µg/ml MEP extract or 10 µM benzo(a)pyrene was added to each well. To control cultures, 0.1% DMSO in fresh medium was added. Twenty-four h after treatment, the cell-conditioned medium was collected by centrifugation and stored at 20°C until ELISA. IL-1, IL-6, and IL-11 levels of conditioned media were determined by ELISA using human Quantikine human kits (R&D Systems Inc., Minneapolis, MN). Concentrations of these cytokines in cell lysate were similarly determined.
Bioactivity assay.
CL5 cells in maintenance medium were plated in 6-cm tissue culture dishes at 5 x 105 cells per dish. After seeding overnight, maintenance medium was changed to experimental medium consisting of RPMI 1640 medium supplemented with 1% charcoal-treated fetal calf serum. After 12 h incubation, the medium was removed and 5 ml fresh experimental medium containing 100 µg/ml MEP extract or 10 µM benzo(a)pyrene was added to each dish. To control cultures, 0.1% DMSO in fresh medium was added. Twenty-four h after treatment, the CL5 cell-conditioned medium was collected by centrifugation and stored at 20°C until use. WI-38 cells in maintenance medium were seeded into 24-well culture plates at 1 x 104 cells per well. After seeding overnight, fibroblasts were serum-deprived for 16 h with serum-free MEM with supplements. Following serum-deprivation, the serum-free medium was replaced with experimental medium, prepared by 1:1 dilution of CL5 cell-conditioned medium with serum-free MEM with supplements. The experimental medium was replaced at 48 h after incubation. Cell growth of WI-38 fibroblast was determined at 96 h. Cells were fixed and stained with sulforhodamine B as described by Skehan et al. (1990). The bound dye was solubilized, and its absorbance was read at 490 nm using an ELISA reader.
Experimental animals and ME inhalation exposure.
Seven-week-old female Wistar rats were purchased from the Animal Center of the College of Medicine, National Taiwan University, Taipei, Taiwan. Before experiments began, the animals were allowed 1 week of acclimation at the animal quarter. In ME inhalation studies, the animals were exposed to 1:10 diluted ME using a head-nose-only inhalation chamber (Technical and Scientific Equipment GMBH, Bad Hamburg, Germany). The animals were exposed to ME from 9 to 10 A.M. and 4 to 5 P.M. daily, Monday through Friday, for 4 weeks. Control rats were exposed to clean air only. The animal maintenance and the inhalation chamber and exposure conditions were described previously (Ueng et al., 2004). The exposure chamber atmospheres were measured using an aerosol monitor model 8520 DUSKTRAK with a cutoff at 10 µm and a combustion analyzer model CA-6200 (TSI, Inc.). The control and ME exposure atmospheres components and their mean concentrations were: particles, 0.5 and 21.5 mg/m3; carbon monoxide, 0.2 and 5.8 ppm; carbon dioxide, 0 and 0.3%; nitric oxide, 0 and 4.5 ppm; nitric dioxide, 0 and 0 ppm; and oxygen, 20.5 and 20.3%, respectively. Animals were killed within 24 h after the last exposure. The Institutional Animal Care and Use Committee of the National Taiwan University College of Medicine approved all animal care and experimental procedures.
Statistical analysis.
The statistical significance of difference between control and treatment groups was evaluated by the Student's t-test of paired data. A p-value <0.05 was considered statistically significant.
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RESULTS |
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In the drug metabolism array study, a visual comparison of the membranes of controls and MEP-treated CL5 cells demonstrated that MEP-treated cells showed increases of CYP1A1, CYP3A7, and UGT2B gene expressions (Fig. 1). Image analysis of transcript intensity indicated that MEP increased CYP1A1, CYP3A7, UGT2B, and UGT1A1 mRNA by 9-, 3-, 4-, and 2-fold, respectively (Table 4). In the cytokine array study, MEP elevated expression of fibroblast growth factor (FGF)-6, FGF-9, IL-1, and IL-22 genes (Fig. 2). Image analysis further showed that MEP increased FGF-6, FGF-9, and vascular endothelial growth factor (VEGF)-D mRNA by 4-, 2-, and 9-fold, respectively; IL-1
and IL-22 by 5- and 6-fold; and TNFSF10 by 5-fold. The results of oncogene, tumor suppressor, and estrogen signaling pathway arrays studies indicated that MEP extract produced 4-, 6-, and 4-fold increases of oncogenes fra-1, c-src, and SHC and resulted in 2-fold increases of tumor suppressor p21 and estrogen response gene COX7RP (Table 4). In contrast, MEP decreased tumor suppressors p53 and Rb expression by about 60%. The data from these five arrays studies collectively showed that MEP up-regulated the expression of 15 genes and down-regulated 2 genes. No remarkable alterations on the expressions of the other 238 genes were detected on the arrays.
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DISCUSSION |
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This study also demonstrates that gene alteration properties of MEP mimic the properties of benzo(a)pyrene, a constituent of MEP. Therefore the biological effects of MEP may be attributed, at least in part, to benzo(a)pyrene and related PAH present in MEP. Induction of IL-1, IL-6, FGF-9, and VEGF-D by MEP and benzo(a)pyrene was associated with increased peroxide formation and blocked by the antioxidant N-acetylcysteine in CL5 cells. These data and the CYP1A1 and CYP1B1 induction data together strongly suggest a possible sequent series of events leading to upregulation of proinflammatory cytokines and growth factors. The events involve (1) induction of metabolic enzymes by MEP and benzo(a)pyrene, which increases metabolic activation of protoxicants and formation of reactive oxygen species, and (2) the increased cellular oxidative stress in turn would activate, via signaling pathways, those transcription factors such as activator protein-1 and nuclear factor-kappa B, which could induce the expression of proinflammatory cytokines and growth factors. Additional studies are required to confirm this hypothesis.
MEP and benzo(a)pyrene decreased Rb mRNA in the human lung cells, unlike the increases observed with the other genes. The exact reasons for the decrease are still not clear. The tumor suppressor Rb plays a crucial role in cell cycle control in which phosphorylation of Rb protein is necessary for cell progression though G1 phase (Shackelford et al., 1999). The decrease of Rb expression possibly indicated that exposure to environmental chemicals might contribute to dysregulation of cell cycle controls by altering the expression of Rb and related cell cycle regulators. Benzo(a)pyrene elevated the level of IL-15 mRNA in CL5 cells. IL-15 plays unique roles in both innate and adaptive immune cell homeostasis (Lodolce et al., 2002
). The significance of benzo(a)pyrene induction of IL-15 in lung epithelial cells remains to be further elucidated. Dissimilar to their counterparts of CL5 cells, the proinflammatory cytokines and growth factors of BEAS-2B cells were refractory to the stimulatory effects of MEP and benzo(a)pyrene. Concentration-response and time-course studies using additional cancer and noncancer cell lines such as normal human bronchial cells will be required to determine whether this dissimilarity was a reflection of differences in the induction kinetics in these two specific cell lines or an indication of selectivity of gene induction in cancer cells.
Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent arylhydrocarbon receptor agonist, is associated with chronic obstructive pulmonary disease and increased risk to lung cancer in humans (Steenland et al., 1999). cDNA microarray analysis of human lung adenocarcinoma A549 cells revealed that 68 out of 2091 genes changed their expression levels at 24 h following treatment of the cells with 0.1, 1, and 10 nM TCDD (Martinez et al., 2002
). With these gene changes there was induction of metabolic enzymes CYP1A1 and CYP1B1, cytokines IL-8 and leukemia inhibitory factor, and growth factors FGF-2 and VEGF. In parallel to TCDD, benzo(a)pyrene and MEP induced the same metabolic enzymes and the genes of the same families in human lung adenocarcinoma CL5 cells. These findings suggest the possibility that TCDD, benzo(a)pyrene, and MEP induced similar changes in gene categories of lung adenocarcinomal cell lines. Given that CYP1A1 induction is a hallmark indicating the biochemical effect of arylhydrocarbon receptor agonists, these present findings also suggest that it would be important to investigate the role of arylhydrocarbon receptors in the integrated pathways leading to formation and progression of lung adenocarcinoma.
Exposures to diesel exhaust and DEP have been associated with respiratory and allergic diseases such as asthma. DEP has been reported to promote release of specific cytokines, chemokines, and related mediators, which initiates a cascade resulting in airway inflammation (Pandya et al., 2002). Exposure of BEAS-2B cells to 40 to 300 µg/ml DEP for 24 or 48 h produced increases of IL-6 and chemokine IL-8 production (Steerenberg et al., 1998
). Treatment of BEAS-2B cells with 5 and 25 µg/ml DEP for 24 h increased production of granulocyte macrophage-colony stimulating factor and regulated on activation, normal T cells expressed and secreted as well as IL-8 (Kawasaki et al., 2001
). Similar to DEP, MEP induced IL-6 expression in CL5 cells. However, the results of cytokine array studies indicated that MEP had no marked effects on IL-8 or granulocyte macrophage-colony stimulating factor in CL5 cells (data not shown). Further studies will be needed to better define the effects of MEP on those cytokines, chemokines, and mediators inducible by DEP in order to properly assess the respiratory health risk of ME exposure, relative to that of DE exposure.
The present study showed that MEP and benzo(a)pyrene increased the releases of IL-6 and IL-11, but not of IL-1, by CL5 cells. IL-1
and its immature form, pro-IL-1
, were found to remain mainly in the cytoplasm and carried out their activities intracellularly (Roux-Lombard, 1998
). Accordingly, the present ELISA data also demonstrated that MEP and benzo(a)pyrene increased IL-1
production in CL5 cell lysate, but not in culture medium. FGF-9, which was originally called glial-activating factors, was discovered as a secreted factor from human glioma cell line. Expression of FGF-9 in COS cells demonstrated that it was glycosylated and efficiently secreted (Miyamoto et al., 1993
). However, the effects of MEP and benzo(a)pyrene on FGF-9 protein expression of CL5 cells still need to be explored.
A major finding in the present study was the stimulation of cell growth in human lung fibroblast by conditioned medium from MEP- or benzo(a)pyrene-induced CL5 epithelial cells. An underlying basis for the stimulatory effect was the expression of receptors for the proinflammatory cytokine and growth factor induced by the environmental chemicals. The lung cell types which could express receptors for IL-1, IL-6, FGF-9, and VEGF-D included macrophage, mast cells, and endothelium, in addition to epithelium and fibroblast (Heinrich et al., 2003
; Roux-Lombard, 1998
). With such wide distribution of the receptors, it is not unreasonable that MEP and benzo(a)pyrene can stimulate epithelial cells interactions with a variety of cells, including fibroblast, macrophage, and other cell types, that play a role in maintaining the homeostasis of the microenvironment in the lung.
In the present studies, CL5 cells were treated with 100 µg/ml MEP extract or 10 µM benzo(a)pyrene in cell medium for 6 h. The following calculation was done to further assess the significance of the concentrations of the environmental chemicals used. The yield of MEP extract from MEP was 56% (g/g). Consequently, 100 µg/ml MEP extract was equivalent to 179 µg/ml (1.79 x 105 mg/m3 ) MEP in CL5 cell medium. A typical PM10 concentration in ME was 228 mg/ m3. Therefore the MEP concentration in cell medium would be at least 785 times higher than the concentration in ME. Benzo(a)pyrene concentration in MEP extract was 20.2 ng/mg (Table 3). Ten µM benzo(a)pyrene in CL5 cell medium was equivalent to 125 mg/ml MEP extract, which would be 1250-fold higher than the 100 µg/ml MEP extract used to treat CL5 cells. The results of these calculation analysis indicated that the MEP extract and benzo(a)pyrene concentrations for treatment of CL5 cells were not compatible with the environmental levels that humans may be exposed to. Extrapolation of these findings with the treated CL5 cells to adverse health effects associated with human exposure requires further experimental studies and physiological toxicokinetic modeling and considerations.
The present findings with CL5 cells have provided new mechanistic and predictive information regarding the gene regulation properties of MEP. This is supported by the findings of experimental animal study that inhalation exposure to ME under environmentally relevant conditions induced CYP1A1, FGF-9, and IL-1 genes expression in rat lung (Fig. 10). The induction by ME in rat lung also suggests that the MEP-mediated induction of metabolism, growth factor, and inflammatory cytokine genes in human lung adenocarcinoma CL5 cells is not just an artifact of a tumor cell line. The induction in CL5 cells indicates several possible consequences, such as that, upon exposure to MEP, the lung tumor cells might increase production of cytokines including the proangiogenic FGF-9, which would increase the invasiveness of the tumor cells. Induction of the same metabolic enzyme and cytokines in CL5 cells and rat lung by MEP and ME emphasizes that it may be necessary to study their differential toxicological effects on normal and tumor cells.
In summary, MEP and benzo(a)pyrene induce an array of altered gene expression including induction of genes involved in metabolic activation, inflammation, and angiogenesis in lung epithelial cells. The findings on induction of FGF-9, VEGF-D, IL-1, and IL-11 have further elucidated the roles of environment and gene interactions which may be important in the promotion of lung diseases including cancer.
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NOTES |
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ACKNOWLEDGMENTS |
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REFERENCES |
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Asadullah, K., Haeussler-Quade, A., Gelrich, S., Hanneken, S., Hansen-Hagge, T. E., Docke, W. D., Volk, H. D., and Sterry, W. (2000). IL-15 and IL-16 overexpression in cutaneous T-cell lymphomas: Stage-dependent increase in mycosis fungoides progression. Exp. Dermatol. 9, 248251.[CrossRef][ISI][Medline]
Auernhammer, C. J., and Melmed, S. (1999). Interleukin-11 stimulates proopiomelanocortin gene expression and adrenocorticotropin secretion in corticotroph cells: Evidence for a redundant cytokine network in the hypothalamo-pituitary-adrenal axis. Endocrinology 140, 15591566.
Cancilla, B., Ford-Perris, M. D., and Bertram, J. F. (1999). Expression and localization of fibroblast growth factors and fibroblast growth factor receptors in the developing rat kidney. Kidney Int. 56, 20252039.[CrossRef][ISI][Medline]
Carmichael, J., DeGraff, W. G., Gazdar, A. F., Minna, J. D., and Mitchell, J. B. (1987). Evaluation of a tetrazolium based semiautomated colorimetric assay: Assessment of chemosensitivity testing. Cancer Res. 47, 936942.[Abstract]
Chan, C. C., Lin, S. H., and Her, G. R. (1993). Student's exposure to volatile organic compounds while commuting by motorcycle and bus in Taipei City. J. Air Waste Manage. Assoc. 43, 12311238.[ISI][Medline]
Dohr, O., Vogel, C., and Abel, J. (1995). Different response of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-sensitive genes in human breast cancer MCF-7 and MDA-MB 231 cells. Arch. Biochem. Biophys. 321, 405412.[CrossRef][ISI][Medline]
Guidice, J. M., Marez, D., Sabbagh, N., Legrand-Andreoletti, M., Spire, C., Alcaide, E., Lafitte, J. J., and Broly, F. (1997). Evidence for CYP2D6 expression in human lung. Biochem. Biophys. Res. Commun. 241, 7985.[CrossRef][ISI][Medline]
Hakkola, J., Pasanen, M., Hukkanen, J., Pelkonen, O., Maenpaa, J., Edwards, R. J., Boobis, A. R., and Raunio, H. (1996). Expression of xenobiotic-metabolizing cytochome P450 forms in human full-term placenta. Biochem. Pharmacol. 51, 403411.[CrossRef][ISI][Medline]
Heinrich, P. C., Behmann, I., Haan, S., Hermanns, H. M., Muller-Newen, D., and Schaper, F. (2003). Principles of interleukin (IL)-6-type cytokine signaling and its regulation. Biochem. J. 374, 120.[CrossRef][ISI][Medline]
Jemma, C. A., Shore, P. R., and Widdicombe, K. A. (1995). Analysis of C1-C16 hydrocarbons using dual-column capillary GC: Application to exhaust emissions from passenger car and motorcycle engine. J. Chomatogr. Sci. 33, 3438.
Jordan, J. E., Motalto, M. C., and Stahl, G. L. (2001). Inhibition of mannose-binding lectin reduces postischemic myocardial reperfusion injury. Circulation 104, 14131418.
Kawasaki, S., Takizawa, H., Takami, K., Desaki, M., Okazaki, H., Kasama, T., Kobayashi, K., Yamamoto, K., Nakahara, K., Tanaka, M., et al. (2001). Benzene-extract induced components are important for the major activity of diesel exhaust particles: Effect on interleukin-8 gene expression in human bronchial epithelial cells. Am. J. Respir. Cell Mol. Biol. 24, 419426.
Kuo, M. L., Jee, S. H., Chou, M. H., and Ueng, T. H. (1998). Involvement of oxidative stress in motorcycle exhaust particle-induced DNA damage and inhibition of intercellular communication. Mutat. Res. 413, 143150.[ISI][Medline]
Lebel, C. P., Ishiropoulo, H., and Bondy, S. C. (1992). Evaluation of the probe 2',7'-dichlorofluorescin as an indicator of reactive oxygen species formation and oxidative stress. Chem. Res. Toxicol. 5, 227231.[CrossRef][ISI][Medline]
Lee, C. C., Liao, J. W., and Kang, J. J. (2004). Motorcycle exhaust particles induce airway inflammation and airway responsiveness in BALB/c mice. Toxicol. Sci. 79, 326334.
Lodolce, J. P., Burkett, P. R., Koka, R. M., Boone, D. L, and Ma, A. (2002). Regulation of lymphoid homoestasis by interleukin-15. Cytokine Growth Factor Rev. 13, 429439.[CrossRef][ISI][Medline]
Martinez, J. M., Afshari, C. A., Bushel, P. R., Masuda, A., Takahashi, T., and Walker, N. J. (2002). Differential toxicogenomic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin in malignant and nonmalignant human airway epithelial cells. Toxicol. Sci. 69, 409423.
Matsumoto-Yoshitomi, S., Habshita, J., Nomura, C., Kuroshima, K., and Kurokawa, T. (1997). Autocrine transformation by fibroblast growth factor 9 (FGF-9) and its possible participation in human oncogenesis. Int. J. Cancer 71, 442450.[CrossRef][ISI][Medline]
Mills, P. R., Davies, R. J., and Devalia, J. L. (1999). Airway epithelial cells, cytokines, and pollutants. Am. J. Respir. Crit. Care Med. 160, S38S43.
Miyamoto, M., Nauro, K., Seko, C., Matsumoto, S., Kondo, T., and Kurokawa, T. (1993). Molecular cloning of a novel cytokine cDNA encoding the ninth member of the fibroblast growth factor family, which has a unique secretion property. Mol. Cell. Biol. 13, 42514259.[Abstract]
Mohri, M., Reinach, P. S., Kanayama, A., Shimizu, M., Moskovitz, J., Hisatsune, T., and Miyamoto, Y. (2002). Suppression of the TNF-induced increase in IL-1
expression by hypochlorite in human corneal epithelial cells. Invest. Ophthalmol. Vis. Sci. 43, 31903195.
Ornitz, D. M., and Itoh, N. (2001). Fibroblast growth factors. Genome Biol. 2, 112.
Pandya, R. J., Solomon, G., Kinner, A., and Balmes, J. R. (2002). Diesel exhaust and asthma: Hypothesis and molecular mechanisms. Environ. Health Perspect. 110(Suppl. 1), 103112.
Roux-Lombard, P. (1998). The interleukin-1 family. Eur. Cytokine Netw. 9, 565576.[ISI][Medline]
Rutanen, J., Leppanen, P., Tuomisto, T. T., Rissanen, T. T., Hiltunen, M. O., Vajanto, I., Niemi, M., Hakkinen, T., Karkola, K., Stacker, S. A., et al. (2003). Vascular endothelial growth factor-D expression in human atherosclerotic lesions. Cardiovasc. Res. 59, 971979.[CrossRef][ISI][Medline]
Schilter, B., Andersen, M. R., Acharya, C., and Omiecinski, C. J. (2000). Activation of cytochrome P450 gene expression in the rat brain by phenobarbital-like inducers. J. Pharmacol. Exp. Ther. 294, 916922.
Shackelford, R. E., Kaufmann, W. K., and Paules, R. S. (1999). Cell cycle control, checkpoint mechanisms, and genotoxic stress. Environ. Health Perspect. 107(Suppl. 1), 524.[ISI][Medline]
Skehan, P., Storeng, R., Scudiero, D., Monks, A., McMahon, J., Vistica D, Warren, J. T., Bokesch, H., Kenney, S., and Boyd, M. R. (1990). New colorimetric cytotoxicity assay for anticancer-drug screening. J. Natl. Cancer Inst. 82, 11071112.[Abstract]
Stacker, S. A., Caesar, C., Baldwin, M. E., Thornton, G. E., Williams, R. A., Prevo, R., Jackson, D. G., Nishikawa, S., Kubo, H., and Achen, M. G. (2001). VEGF-D promotes the mestastatic spread of tumor cells via the lymphatics. Nat. Med. 7, 186191.[CrossRef][ISI][Medline]
Steenland, K., Piacitelli, L., Deddens, J., Fingerhut, M., and Chang, L. I. (1999). Cancer, heart disease, and diabetes in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. J. Natl. Cancer Inst. 91, 779786.
Steerenberg, P. A., Zonnenberg, J. A., Dormans, J. A., Joon, P. N., Wouters, I. M., van Bree, L., Scheepers, P. T., and Van Loveren, H. (1998). Diesel exhaust particles induced release of interleukin 6 and 8 by (primed) human bronchial epithelial cells (BEAS 2B) in vitro. Exp. Lung Res. 24, 85100.[ISI][Medline]
Tsai, S. J., Wu, M. H., Chen, H. M, Chuang, P. C., and Wing, L. Y. (2002). Fibroblast growth factor-9 is an endometrial stromal growth factor. Endocrinology 143, 27152721.
Tzeng, H. P., Yang, R. S., Ueng, T. H., Lin-Shiau, S. Y., and Liu, S. H. (2003). Motorcycle exhaust particles enhanced vasoconstriction in organ culture of rat aortas and involve reactive oxygen species. Toxicol. Sci. 75, 6673.
Ueng, T. H., Hu, S. H., Chen, R. M., Wang, H. W., and Kuo, M. L. (2000). Induction of cytochome P450 1A1 in human hepatoma HepG2 and lung carcinoma NCI-H322 cells by motorcycle exhaust particulate. J. Toxicol. Environ. Health A 60, 101119.[CrossRef][ISI][Medline]
Ueng, T. H., Wang, H. W., Hung, C. C., and Chang, H. L. (2004). Effects of motorcycle exhaust inhalation exposure on cytochome P-450 2B1, antioxidant enzymes, and lipid peroxidation in rat liver and lung. J. Toxicol. Environ. Health A 67, 875888.[CrossRef][Medline]
Wang, H. W., Chen, T. L., Yang, P. C., and Ueng, T. H. (2001). Induction of cytochomes P450 1A1 and 1B1 by emodin in human lung adenocarcinoma cell line CL5. Drug Metab. Dispos. 29, 12291235.
Wang, H. W., Chen, F. W., and Ueng, T. H. (2002). Induction of cytochomes P-450 1A1 and 1B1 by motorcycle exhaust particulate in human breast cancer MCF-7 cells. J. Toxicol. Environ. Health A 65, 101117.
Yin, X. J., Ma, J. Y. C., Antonini, J. M., Castranova, V., and Ma, J. K. H. (2004). Roles of reactive oxygen species and heme oxygenase-1 in modulation of alveolar macrophage-mediated pulmonary immune responses to Listeria monocytogenes by diesel exhaust particles. Toxicol. Sci. 82, 143153.
Zhang, J., Xu, K., Ambati, B., and Yu, F. S. X. (2003). Toll-like receptor 5-mediated corneal epithelial inflammatory responses to Pseudomonas aeruginosa flagellin. Invest. Ophthalmol. Vis. Sci. 44, 42474254.
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