Epidemiological studies suggest that chronic activation of the inflammatory response may affect the initiation and/or progression of cancer. Oxidants generated during an inflammatory response can oxidize endogenous proteins, lipids, and DNA. Mutations introduced into DNA due to oxidative damage can be retained by the tissue as a result of the proliferative response necessary to replace oxidatively damaged cells. Tumor Necrosis Factor- α (TNF α) and Interleukin-1 (IL-1) are key regulators of the inflammatory response. Current signaling models predict that TNF α and IL-1 share, in some instances, overlapping signaling pathways leading to activation of similar subsets of transcription factors. These results contrast data demonstrating that IL-1 and TNF α knock-out animals differ in their sensitivities to known inflammatory response activators. To resolve the signaling pathway versus biological response difference, Multidimensional Protein Identification Technology (MudPIT) is being used to analyze the cellular proteome of control, IL-1 or TNF α stimulated cells. Analysis of total cell lysates on a LCQ mass spectrometer identified over 3000 unique peptides. Changes in IL-1 or TNF α pathway components not previously known to be regulated were detected. We are currently confirming these differences using Western analysis of cell lysates isolated from control or stimulated cells. This analysis will then be complemented using GIST (Global Internal Standard Technology) to differentially label paired samples (IL-1 verus TNF α), that will be analyzed simultaneously on a LTQ mass spectrometer, to identify peptides that differ in abundance. Results of our studies have demonstrated the feasibility of using mass spectrometry for the analysis of complex cellular proteomes and identified new targets regulating IL-1 and TNF α signaling pathways. These data will help in defining the role inflammation plays in cancer and will the lead to the identification of more specific cellular targets for therapy.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]