leukotriene-d4 and Cell-Transformation--Neoplastic

It has recently been demonstrated that cysteinyl leukotrienes are involved in a variety of proinflammatory and neoplastic functions. This article gives an up-to-date overview of the present knowledge of these bioactive lipid molecules. Inflammatory bowel disease (IBD) and colorectal cancer (CRC) are applied as models of their cellular actions. It is described how signalling cascades initiated by cysteinyl leukotrienes represent alternative ways in which IBD might progress and lead to the development and propagation of CRC, and as such represent potential targets for future therapeutic regimens to manage chronic inflammatory disorders and cancer.

Topics: Cell Membrane; Cell Proliferation; Cell Transformation, Neoplastic; Colorectal Neoplasms; Humans; Inflammation Mediators; Inflammatory Bowel Diseases; Leukotriene D4; Leukotrienes; Receptors, Leukotriene; Signal Transduction

Increased levels of the inflammatory mediator leukotriene D4 (LTD4) are present at sites of inflammatory bowel disease, and such areas also exhibit an increased risk for subsequent cancer development. It is known that LTD4 affects the expression of many proteins that influence survival and proliferation of intestinal epithelial cells. We demonstrate here that after LTD4 exposure, beta-catenin translocates to the nucleus where it signals activation of the TCF/LEF family of transcription factors. These events are mediated via a phosphatidylinositol 3-kinase-dependent phosphorylation of the inhibitory Ser-9 residue of glycogen synthase kinase 3beta. We also show that in the presence of LTD4, free beta-catenin translocates to the mitochondria where it associates with the cell survival protein Bcl-2. We hypothesize that LTD4 may enhance cell survival via activation of beta-catenin signaling, in particular, by promoting the association of beta-catenin with Bcl-2 in the mitochondria. Similar to Wnt-1 signaling, LTD4 signals an increased level of free beta-catenin and elevated TCF/LEF promotor activity. This work in intestinal epithelial cells further lends credence to the idea that inflammatory signaling pathways are intrinsically linked with potential oncogenic signals involved in cell survival and apoptosis.

Topics: Apoptosis; beta Catenin; Cell Line; Cell Survival; Cell Transformation, Neoplastic; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Intestinal Mucosa; Leukotriene D4; Microscopy, Fluorescence; Mitochondria; Protein Transport; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; TCF Transcription Factors