ANXA8 down-regulation by EGF-FOXO4 signaling is involved in cell scattering and tumor metastasis of cholangiocarcinoma.
OBJECTIVE
The sarcomatoid change in cholangiocarcinoma (CC) contributes to more aggressive intrahepatic spread and widespread metastasis. Therefore, the aim of this study was to identify the molecular mechanisms of CC metastasis during tumor progression and sarcomatoid change.


METHODS
Using the subtraction suppression hybridization (SSH) method, we identified altered expression of the candidate gene ANXA8 and epidermal growth factor receptor (EGFR) in sarcomatoid CC cells. We assessed ANXA8 expression during the progression of CC in cells and tissues and examined its functional significance by performing in vitro cell experiments and using in vivo animal models.


RESULTS
ANXA8 is highly expressed in human and hamster CCs but is down-regulated with tumor dedifferentiation. ANXA8 is transcriptionally down-regulated by epidermal growth factor (EGF), which is correlated with the morphologic changes of the epithelial-to-mesenchymal transition (EMT) in the CC cells. Furthermore, ectopic ANXA8 reverses the morphology of cells, and this is associated with focal adhesion kinase expression and altered F-actin dynamics. EGFR and its downstream targets, phosphatidylinositol-3-kinase and Akt, are linked to the phosphorylation of FOXO4, which leads to the inhibition of ANXA8 transcription. In addition, an in vitro cell invasion assay and in vivo spontaneous metastasis assay reveal that ANXA8 inhibits the cell migratory and metastatic characteristics of CC cells.


CONCLUSIONS
These findings suggest that FOXO4 and ANXA8 play key roles in growth factor-mediated tumor progression and metastasis during the EMT change in CC.
Division of Gastroenterology and Hepatology, Department of Internal Medicine, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea.
Mi-Jin
MJ
Lee
Gyung-Ran
GR
Yu
Hee-Jung
HJ
Yoo
Jong-Hyun
JH
Kim
Byung-Il
BI
Yoon
Yang-Kyu
YK
Choi
Dae-Ghon
DG
Kim
D000199:Actins / Q000378:metabolism; D000818:Animals; D017302:Annexins / Q000378:metabolism*; D001650:Bile Duct Neoplasms / Q000378:metabolism / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000378:metabolism / Q000473:pathology*; D006224:Cricetinae; D015536:Down-Regulation; D066246:ErbB Receptors / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
D000199:Actins; D017302:Annexins; D018797:Cell Cycle Proteins; D051858:Forkhead Transcription Factors; C525394:FoxO4 protein, mouse; D066246:ErbB Receptors; D051417:Focal Adhesion Kinase 1; C496051:Ptk2 protein, mouse