09-272 Sigma-AldrichAnti-phospho-p38α (Thr180/Tyr182) Antibody

Cancer secretomes are a promising source for biomarker discovery. The analysis of cancer secretomes still faces some difficulties mainly related to the intracellular contamination, which hinders the qualification and follow-up validations. This study aimed to establish a high-quality secretome of A549 cells by using the cellular proteome as a reference and to test the merits of this refined secretome for biomarker discovery for non-small cell lung cancer (NSCLC). Using one-dimensional gel electrophoresis followed by liquid-chromatography tandem mass spectrometry, we comprehensively investigated the secretome and the concurrent cellular proteome of A549 cells. A high-quality secretome consisting of 382 proteins was refined from 889 initial secretory proteins. More than 85.3% of proteins were annotated as secreted and 76.8% as extracellular or membrane-bound. The discriminative power of the lung-cancer associated secretome was confirmed by gene expression and serum proteomic data. The elevated level of C4b-binding Protein (C4BP) in NSCLC blood was verified by enzyme-linked immunosorbent assays (ELISA, p = 6.07e-6). Moreover, the serum C4BP level in 89 patients showed a strong association with the clinical staging of NSCLC. Our reference-experiment-driven strategy is simple and widely applicable, and may facilitate the identification of novel promising biomarkers of lung cancer.

In cystic fibrosis (CF), the absence of functional cystic fibrosis transmembrane conductance regulator (CFTR) translates into chronic bacterial infection, excessive inflammation, tissue damage, impaired lung function and eventual death. Understanding the mechanisms underlying this vicious circle of inflammation is important to design better therapies for CF. We found in CF lung biopsies increased immunoreactivity for p38 MAPK activity markers. Moreover, when compared with their non-CF counterpart, airway epithelial cells expressing the most common mutation in CF (CFTRDeltaF508) were more potent at inducing neutrophil chemotaxis through increased interleukin (IL)-6 synthesis when challenged with Pseudomonas aeruginosa diffusible material. We then discovered that in CFTRDeltaF508 cells, the p38 and ERK MAPKs are hyperactivated in response to P. aeruginosa diffusible material, leading to increased IL-6 mRNA expression and stability. Moreover, although TLR5 contributes to p38 MAPK activation upon P. aeruginosa challenge, it only played a weak role in IL-6 synthesis. Instead, we found that the production of reactive oxygen species is essential for IL-6 synthesis in response to P. aeruginosa diffusible material. Finally, we uncovered that in CFTRDeltaF508 cells, the extracellular glutathione levels are decreased, leading to a greater sensitivity to reactive oxygen species, providing an explanation for the hyperactivation of the p38 and ERK MAPKs and increased IL-6 synthesis. Taken together, our study has characterized a mechanism whereby the CFTRDeltaF508 mutation in airway epithelial cells contributes to increase inflammation of the airways.

Inflammation is a central feature of many respiratory diseases. Airway epithelial cells are exposed to many agents present in the air that can alter their function and have important structural consequences for the airways. In this study, 19 Toll-Like Receptors (TLRs) and Nucleotide-binding Oligomerization Domain (NOD)1/NOD2 ligands were screened for their capacity to up-regulate Interleukin-8 (IL-8) and Regulated upon Activation Normal T cell Expressed and Secreted (RANTES) in airway epithelial cells. Three ligands (Pam3CSK4, Poly I:C and C12-ie-DAP) were selected for their capacity to activate different receptor complexes (TLR1/TLR2, TLR3 and NOD1 respectively) while leading to the increase of both IL-8 and RANTES albeit with distinct kinetics. Using protein kinase inhibitors we found that the Nuclear Factor kappaB (NFkappaB) pathway is essential for the transcriptional regulation of both IL-8 and RANTES following the activation of TLR1/TLR2, TLR3 and NOD1. In contrast, the Mitogen-Activated Protein Kinases (MAPKs) Extracellular signal-Regulated Kinase (ERK)1/ERK2 and p38 MAPK were necessary for the transcription of IL-8 but not RANTES. Moreover, we found that the p38 MAPK was implicated in the post-transcriptional regulation of IL-8 following TLR3 activation. The distinction made between pathways involved in the regulation of IL-8 and RANTES gives rise to the possibility of designing more targeted clinical approaches based on the biological functions to be ablated.