Down-regulation of GEP100 causes increase in E-cadherin levels and inhibits pancreatic cancer cell invasion.
OBJECTIVE
Invasion and metastasis are major reasons for pancreatic cancer death and identifying signaling molecules that are specifically used in tumor invasion is of great significance. The purpose of this study was to elucidate the role of GEP100 in pancreatic cancer cell invasion and metastasis and the corresponding molecular mechanism.


METHODS
Stable cell lines with GEP100 knocked-down were established by transfecting GEP100 shRNA vector into PaTu8988 cells and selected by puromycin. qRT-PCR and Western blot were performed to detect gene expression. Matrigel-invasion assay was used to detect cancer cell invasion in vitro. Liver metastasis in vivo was determined by splenic injection of indicated cell lines followed by spleen resection. Immunofluorescence study was used to detect the intracellular localization of E-cadherin.


RESULTS
We found that the expression level of GEP100 protein was closely related to the invasive ability of a panel of 6 different human pancreatic cancer cell lines. Down-regulation of GEP100 in PaTu8988 cells significantly decreased invasive activity by Matrigel invasion assay, without affecting migration, invasion and viability. The inhibited invasive activity was rescued by over-expression of GEP100 cDNA. In vivo study showed that liver metastasis was significantly decreased in the PaTu8988 cells with GEP100 stably knocked-down. In addition, an epithelial-like morphological change, mimicking a mesenchymal to epithelial transition (MET) was induced by GEP100 down-regulation. The expression of E-cadherin protein was increased 2-3 folds accompanied by its redistribution to the cell-cell contacts, while no obvious changes were observed for E-cadherin mRNA. Unexpectedly, the mRNA of Slug was increased by GEP100 knock-down.


CONCLUSIONS
These findings provided important evidence that GEP100 plays a significant role in pancreatic cancer invasion through regulating the expression of E-cadherin and the process of MET, indicating the possibility of it becoming a potential therapeutic target against pancreatic cancer.
Department of Gastroenterology, Second Affiliated Hospital of Zhejiang University College of Medicine, Hangzhou City, Zhejiang Province, China.
Chuan-gao
CG
Xie
Shu-mei
SM
Wei
Jia-min
JM
Chen
Xuan-fu
XF
Xu
Jian-ting
JT
Cai
Qin-yu
QY
Chen
Li-tao
LT
Jia
D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002450:Cell Communication; D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000556:secondary; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology
D015820:Cadherins; D020662:Guanine Nucleotide Exchange Factors; C504483:IQSEC1 protein, human