Document Detail

Differential roles of ERK and Akt pathways in regulation of EGFR-mediated signaling and motility in prostate cancer cells.
MedLine Citation:
PMID:  20562913     Owner:  NLM     Status:  MEDLINE    
Upregulation of epidermal growth factor receptor (EGFR) and subsequent increases in extracellular-regulated kinase (ERK) and Akt signaling are implicated in prostate cancer progression. Impaired endocytic downregulation of EGFR also contributes to oncogenic phenotypes such as metastasis. Thus, understanding the roles of divergent signaling pathways in the regulation of EGFR trafficking and EGFR-driven invasive migration may enable the development of more effective therapies. In this study, we use the human prostate cancer cell lines, DU145 and PC3, to investigate the effects of both the ERK and Akt pathways on epidermal growth factor (EGF)-mediated EGFR signaling, trafficking and cell motility. We show that DU145 and PC3 cells overexpress EGFR and migrate in a ligand (EGF)-dependent manner. Next, we show that pharmacological inhibition of ERK (but not Akt) signaling enhances EGF-induced EGFR activation, ubiquitination and downregulation, and may lead to enhanced receptor turnover. These findings negatively correlate with ERK-mediated threonine phosphorylation of EGFR, implicating it as a possible mechanism. Further, we uncover that EGF promotes disassembly of cell-cell junctions, downregulation of E-cadherin and upregulation of the transcriptional repressor, Snail, typical characteristics of epithelial-mesenchymal transition (EMT). These effects are dependent on activation of Akt, as inhibition of Akt signaling abolishes EGF/EGFR-driven cell migration and EMT. Knockdown of endogenous Snail also prevents EGFR-mediated downregulation of E-cadherin, EMT and cell migration. Surprisingly, inhibition of the ERK pathway augments EGFR-dependent motility, occurring concomitantly with elevation of EGF-induced Akt activity. Collectively, our results suggest that EGF-triggered ERK activation has profound feedback on EGFR signaling and trafficking by EGFR threonine phosphorylation, and Akt has a pivotal role in EGFR-mediated cell migration by activating EMT. More important, our results also suggest that therapeutic targeting of ERK signaling may have undesirable outcomes (for example, augmenting EGFR-driven motility).
Y Gan; C Shi; L Inge; M Hibner; J Balducci; Y Huang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-06-21
Journal Detail:
Title:  Oncogene     Volume:  29     ISSN:  1476-5594     ISO Abbreviation:  Oncogene     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-09-02     Completed Date:  2010-10-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8711562     Medline TA:  Oncogene     Country:  England    
Other Details:
Languages:  eng     Pagination:  4947-58     Citation Subset:  IM    
Department of Obstetrics and Gynecology, St Joseph's Hospital and Medical Center, Phoenix, AZ 85004, USA.
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MeSH Terms
Cadherins / metabolism
Cell Line, Tumor
Cell Movement* / drug effects
Down-Regulation / drug effects
Enzyme Activation / drug effects
Epidermal Growth Factor / pharmacology
Extracellular Signal-Regulated MAP Kinases / metabolism*
Gene Expression Regulation, Neoplastic / drug effects
MAP Kinase Signaling System* / drug effects
Phosphorylation / drug effects
Prostatic Neoplasms / enzymology,  genetics,  pathology*
Protein Transport / drug effects
Proto-Oncogene Proteins c-akt / metabolism*
Receptor, Epidermal Growth Factor / metabolism*
Transcription Factors / metabolism
Up-Regulation / drug effects
Reg. No./Substance:
0/Cadherins; 0/Transcription Factors; 62229-50-9/Epidermal Growth Factor; EC, Epidermal Growth Factor; EC Proteins c-akt; EC Signal-Regulated MAP Kinases

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