Netrin-1 mediates early events in pancreatic adenocarcinoma progression, acting on tumor and endothelial cells.
OBJECTIVE
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. It is characterized by substantial tumor cell invasion and early-stage metastasis. We developed an in vivo model to analyze interactions between cancer and stromal cells during early stages of PDAC.


METHODS
Human pancreatic adenocarcinoma cells were grafted onto the chick chorioallantoic membrane (CAM). Human and chicken GeneChips were used simultaneously to study gene regulation during PDAC cell invasion. Bioinformatic analysis was used to identify human orthologs and cell specificity of gene expression. The effects of netrin-1 encoded by NTN1 were investigated in adhesion, invasion, and apoptosis assays. The effects of NTN1 silencing with small interfering RNAs were investigated in PDAC cells in vivo. NTN1 expression was measured in human PDAC samples.


RESULTS
PDAC cells rapidly invade the CAM stroma and remodel the CAM vasculature. Around 800 stromal genes were up-regulated by >2-fold; the angiogenesis regulators vascular endothelial growth factor D, thrombospondin 1, and CD151 were among the most highly regulated genes. Silencing of tumor cell NTN1, which is up-regulated 4-fold in the PDAC model, inhibited tumor cell invasion in vivo. Netrin-1 conferred apoptosis resistance to tumor and endothelial cells in vitro, induced their invasion, and provided an adhesive substrate for tumor cells. NTN1 and its gene product are strongly overexpressed in human PDAC samples.


CONCLUSIONS
We developed a useful tool to study the invasive mechanisms of early-stage PDAC. Netrin-1 might be an important regulator of pancreatic tumor growth that functions in tumor and endothelial cells.
Dumartin
Laurent
L
Institut National de la Sante et de la Recherche Medicale U920, Talence, France.
Quemener
Cathy
C
Laklai
Hanane
H
Herbert
John
J
Bicknell
Roy
R
Bousquet
Corinne
C
Pyronnet
Stéphane
S
Castronovo
Vincent
V
Schilling
Martin K
MK
Bikfalvi
Andreas
A
Hagedorn
Martin
M
D000230:Adenocarcinoma / Q000473:pathology*; D000818:Animals; D017209:Apoptosis; D018395:CA-19-9 Antigen / Q000097:blood; D045744:Cell Line, Tumor; D002642:Chick Embryo; D018450:Disease Progression; D042783:Endothelial Cells / Q000502:physiology*; D020869:Gene Expression Profiling; D006801:Humans; D009361:Neoplasm Invasiveness; D009414:Nerve Growth Factors / Q000502:physiology*; D000075388:Netrin-1; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D025521:Tumor Suppressor Proteins / Q000502:physiology*
D018395:CA-19-9 Antigen; C000617351:NTN1 protein, human; D009414:Nerve Growth Factors; D025521:Tumor Suppressor Proteins; D000075388:Netrin-1