Celecoxib increases EGF signaling in colon tumor associated fibroblasts, modulating EGFR expression and degradation.
We previously demonstrated that non-toxic doses of Celecoxib induced the immediate phosphorylation of Erk1-2 in colon tumor associated fibroblasts (TAFs), increasing their responsiveness to epidermal growth factor (EGF). We have now identified two concomitant mechanisms explaining the EGF-Celecoxib cooperation. We found that a 24-48h Celecoxib priming increased EGF receptor (EGFR) mRNA and protein levels in colon TAFs, promoting EGF binding and internalization. Celecoxib-primed TAFs showed a reduced EGFR degradation after EGF challenge. This delay corresponded to a deferred dissociation of EEA1 from EGFR positive endosomes and the accumulation of Rab7, pro Cathepsin-D and SQSTM1/p62, suggesting a shared bottleneck in the pathways of late-endosomes/autophagosomes maturation. Celecoxib modulated the levels of target proteins similarly to the inhibitors of endosome/lysosome acidification Bafilomycin-A1 and NH(4)Cl. Cytoplasmic vesicles fractionation showed a reduced maturation of Cathepsin-D in late endosomes and an increased content of EGFR and Rab7 in lysosomes of Celecoxib-treated TAFs.Our data indicate a double mechanism mediating the increased response to EGF of colon TAFs treated with Celecoxib. While EGFR overexpression could be targeted using anti EGFR drugs, the effects on endosome trafficking and protein turnover represents a more elusive target and should be taken into account for any long-term therapy with Celecoxib.
['Venè|Roberta|R|', 'Tosetti|Francesca|F|', 'Minghelli|Simona|S|', 'Poggi|Alessandro|A|', 'Ferrari|Nicoletta|N|', 'Benelli|Roberto|R|']
D015153:Blotting, Western D000068579:Celecoxib D045744:Cell Line, Tumor D049109:Cell Proliferation D003110:Colonic Neoplasms D052246:Cyclooxygenase 2 Inhibitors D004815:Epidermal Growth Factor D066246:ErbB Receptors D005347:Fibroblasts D005434:Flow Cytometry D005455:Fluorescent Antibody Technique D006801:Humans D021381:Protein Transport D060888:Real-Time Polymerase Chain Reaction D015398:Signal Transduction
celecoxib colon fibroblast EGFR