• Toxicological Research
• /
• v.21 no.4
• /
• pp.347-353
• /
• 2005

Eukaryotic initiation factor 4E (elF4E) is a key element for cap-dependent protein translation controlled by affinity between elF4E and 4E-binding protein 1 (4E-BP1). Rapamycin can also affect protein translation by regulating 4E-BP1 phosphorylation. Tobacco-specific nitrosamine, 4(N-methyl-N-nitrosamino )-1-(3-pyridyl)-1-butanone (NNK) is a strong lung carcinogen, but its precise lung cancer induction mechanism remains unknown. Relative roles of cap-dependent and -independent protein translation in terms of NNK-induced lung carcinogenesis were elucidated using normal human bronchial epithelial cells. NNK concentrations applied in this study did not decrease cell viability. Addition of NNK restored rapamycin-induced decrease of protein synthesis and rapamycin-induced phosphorylation of 4E-BP1, and increased expression levels of mTOR, ERK1/2, p70S6K, and Raf-1 in a concentration-dependent manner. NNK also caused perturbation of normal cell cycle progression. Taken together, NNK might cause toxicity through the combination of restoration of 4E-BP1 phosphorylation and increase of elF4E as well as mTOR protein expression, interruption of Raf1/ERK as well as the cyclin G-associated p53 network. Our data could be applied towards elucidation of the molecular basis for lung cancer treatment.

• Clinical and Experimental Pediatrics
• /
• v.49 no.9
• /
• pp.977-982
• /
• 2006

Purpose : There has been an increasing amount of literature concerning the association between Mycoplasma pneumoniae and asthma pathogenesis. Interleukin(IL)-6 stimulates the differentiation of monocytes, and can promote Th2 differentiation and simultaneously inhibit Th1 polarization. IL-8 is a potent chemoattractant and, it has been suggested, has a role in asthma pathogenesis. Nitric oxide (NO) synthesized by airway epithelium may be important in the regulation of airway inflammation and reactivity. Vascular endothelial growth factor(VEGF) has been reported to be a mediator of airway remodeling in asthma. We investigated the effects of M. pneumoniae on IL-6, IL-8, NO and VEGF production in human respiratory epithelial cells. Methods : A549 cells were cultured and inoculated with M. pneumoniae at a dose of 20 cfu/cell. After infection, the presence of M. pneumoniae in epithelial cell cultures was monitored by immunofluorescence and confirmed by polymerase chain reaction(PCR) detection. IL-6, IL-8 and VEGF were determined by an enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction. NO was measured using the standard Griess reaction. Results : In A549 cells, M. pneumoniaeinduced IL-6, IL-8, NO and VEGF release in time-dependent manners. It also induced mRNA expression of IL-6, IL-8 and VEGF in similar manners. Conclusion : These observations suggest that M. pneumoniae might have a role in the pathogenesis of the allergic inflammation of bronchial asthma.