GEP100/Arf6 is required for epidermal growth factor-induced ERK/Rac1 signaling and cell migration in human hepatoma HepG2 cells.
BACKGROUND
Epidermal growth factor (EGF) signaling is implicated in the invasion and metastasis of hepatoma cells. However, the signaling pathways for EGF-induced motility of hepatoma cells remain undefined.


RESULTS
We found that EGF dose-dependently stimulated the migration of human hepatoma cells HepG2, with the maximal effect at 10 ng/mL. Additionally, EGF increased Arf6 activity, and ectopic expression of Arf6 T27N, a dominant negative Arf6 mutant, largely abolish EGF-induced cell migration. Blocking GEP100 with GEP100 siRNA or GEP100-△PH, a pleckstrin homology (PH) domain deletion mutant of GEP100, blocked EGF-induced Arf6 activity and cell migration. EGF also increased ERK and Rac1 activity. Ectopic expression GEP100 siRNA, GEP100-△PH, or Arf6-T27N suppressed EGF-induced ERK and Rac1 activity. Furthermore, blocking ERK signaling with its inhibitor U0126 remarkably inhibited both EGF-induced Rac1 activation as well as cell migration, and ectopic expression of inactive mutant form of Rac1 (Rac1-T17N) also largely abolished EGF-induced cell migration.


CONCLUSIONS
Taken together, this study highlights the function of the PH domain of GEP100 and its regulated Arf6/ERK/Rac1 signaling cascade in EGF-induced hepatoma cell migration. These findings could provide a rationale for designing new therapy based on inhibition of hepatoma metastasis.
Department of Physiology, Nanjing Medical University, Nanjing, China.
ZhenZhen
Z
Hu
Jun
J
Du
Ling
L
Yang
YiChao
Y
Zhu
Yu
Y
Yang
DaTong
D
Zheng
Akimasa
A
Someya
Luo
L
Gu
Xiang
X
Lu
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000704:Analysis of Variance; D002070:Butadienes; D006528:Carcinoma, Hepatocellular / Q000503:physiopathology*; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D015151:Immunoblotting; D066298:In Vitro Techniques; D008856:Microscopy, Fluorescence; D020125:Mutation, Missense; D009362:Neoplasm Metastasis / Q000503:physiopathology*; D009570:Nitriles; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
D000089982:ADP-Ribosylation Factor 6; D002070:Butadienes; D020662:Guanine Nucleotide Exchange Factors; C504483:IQSEC1 protein, human; D009570:Nitriles; C107953:RAC1 protein, human; D034741:RNA, Small Interfering; C113580:U 0126; D004815:Epidermal Growth Factor; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; D020830:rac1 GTP-Binding Protein