[Show abstract][Hide abstract] ABSTRACT: The lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4) signaling pathway in alveolar epithelial cells plays an important role in many pathologic processes such as acute lung injury (ALI). The single immunoglobulin IL-1 receptor-related protein (SIGIRR) is an inhibitor of LPS-TLR4 signaling, but its expression and function in alveolar epithelial cells are still unknown. In this study, we examined the expression of SIGIRR in normal human lung tissue using immunohistochemistry, reverse transcription-PCR (RT-PCR) and Western blot and found that SIGIRR was expressed in alveolar epithelial cells. Treatment of an alveolar epithelial cell line, A549, with LPS and we observed a downregulation of SIGIRR mRNA, which returned to normal levels 24h after LPS exposure. A549 cells were then transfected with a SIGIRR eukaryotic expression vector to over-express SIGIRR or, as a control, with an empty vector. Following LPS exposure, the transcriptional activity of NF-kappaB was measured using a dual-luciferase reporter assay system, and the concentration of IL-1beta, TNF-alpha and IL-6 was determined by ELISA, and cell proliferation was measured by MTT. In A549 cells that over-expressed SIGIRR, LPS treatment resulted in a significant decrease in the transcriptional activity of NF-kappaB and cell growth inhibition ratio, as well as lower levels of secreted IL-1beta, TNF-alpha and IL-6. In conclusion, SIGIRR in A549 cells inhibits the transcriptional activity of NF-kappaB and reduces the amount cytokines produced, protecting these cells from acute LPS-induced damage.
No preview · Article · Nov 2009 · Chemico-biological interactions
[Show abstract][Hide abstract] ABSTRACT: Background and objective NOK (Novel Oncogene with Kinase-domain) is a newly identified receptor protein-tyrosine kinases (RPTKs) subfamily, which possesses strong oncogenic potential including enhancing cell transformation, tumorigenesis, invasion and metastasis. However, NOK protein lacks extracellular domain, and how the NOK is activated by the membrane receptor and the expression of NOK in non small cell lung cancer (NSCLC) are not clear. Our aim of this study was to investigate the expressions of NOK, EGFR proteins in NSCLC. Methods The expression rates of NOK, EGFR proteins in 155 cases with NSCLC was deteced by immunohistochemical stain; The clinical correlations between two proteins were analyzed by statistics. Results The NOK positive expression was mainly located in cytoplasm and EGFR was mainly located in the plasma membrane and cytoplasm. NOK, EGFR proteins were high expressed in NSCLC and there were extremely differences comparing the expression of NOK, EGFR proteins in squamous cell lung cancer, lung adenocarcinoma with those in corresponding normal tissue respectively (P < 0.001); and there were no significant differences between the two kinds of the cancers for their comparison of NOK, EGFR expression (P=0.099; P=0.23); however, there were significant differences for NOK and EGFR expression among histological grades and TNM stages in squamous cell lung cancers, lung adenocarcinoma (P < 0.01). There were correlation between positive and intensity of NOK and EGFR expression in whatever total NSCLC or squamous cell lung cancer or lung adenocarcinoma (P < 0.001), while the correlation coefficients(rs) were 0742, 0.722, 0.756 respectively. Conclusion The NOK proteins are highly expressed in the NSCLC, and the expression rates of NOK proteins are correlated with the cancers’ histological grades and TNM stages, which may be concern with tumorgenesis and progression; the positive expression rate and intensity of NOK protein correlate well with the expression of EGFR protein in NSCLC, which the activation of NOK probably owe to EGFR activation, all that would provide evidence for further study on the effective mechanism of NOK in the tumorigenesis or tumor progression.