alteration of egfr spatiotemporal dynamics suppresses signal transduction表皮生长因子受体的改变时空动力学抑制信号转导.pdfVIP

Alteration of EGFR Spatiotemporal Dynamics Suppresses Signal Transduction 1 2 1,3 Harmony F. Turk , Rola Barhoumi , Robert S. Chapkin * 1 Program in Integrative Nutrition and Complex Diseases, Texas A M University, College Station, Texas, United States of America, 2 Image Analysis Laboratory, Texas A M University, College Station, Texas, United States of America, 3 Center for Environmental and Rural Health, Texas A M University, College Station, Texas, United States of America Abstract The epidermal growth factor receptor (EGFR), which regulates cell growth and survival, is integral to colon tumorigenesis. Lipid rafts play a role in regulating EGFR signaling, and docosahexaenoic acid (DHA) is known to perturb membrane domain organization through changes in lipid rafts. Therefore, we investigated the mechanistic link between EGFR function and DHA. Membrane incorporation of DHA into immortalized colonocytes altered the lateral organization of EGFR. DHA additionally increased EGFR phosphorylation but paradoxically suppressed downstream signaling. Assessment of the EGFR- Ras-ERK1/2 signaling cascade identified Ras GTP binding as the locus of the DHA-induced disruption of signal transduction. DHA also antagonized EGFR signaling capacity by increasing receptor internalization and degradation. DHA suppressed cell proliferation in an EGFR-dependent manner, but cell proliferation could be partially rescued by expression of constitutively active Ras. Feeding chronically-inflamed, carcinogen-injected C57BL/6 mice a fish oil containing diet enriched in DHA recapitulated the effects on the EGFR signaling axis observed in cell culture and additionally suppressed tumor formation. We conclude that DHA-induced alteration