title: The proprotein convertase PC5/6 is protective against intestinal tumorigenesis: in vivo mouse model.
abstract: BACKGROUND
  The secretory basic amino acid-specific proprotein convertases (PCs) have often been associated with cancer/metastasis. By controlling the cleavage of cancer-associated proteins, PCs play key roles in multiple steps of cancer development. Most analyses of the implication of PCs in cancer/metastasis relied on the use of in vitro overexpression systems or inhibitors that can affect more than one PC. Aside from the role of furin in salivary gland tumorigenesis, no other in vivo genetic model of PC-knockout was reported in relation to cancer development.
  
  
  RESULTS
  Since PC5/6 is highly expressed in the small intestine, the present study examined its in vivo role in intestinal tumorigenesis. Analysis of human intestinal tumors at various stages showed a systematic down-regulation of PC5/6 expression. Since gene inactivation of PC5/6 leads to lethality at birth, we generated mice lacking PC5/6 in enterocytes and analyzed the impact of the presence or absence of this PC in the mouse ApcMin/+ model that develops numerous adenocarcinomas along the intestinal tract. This resulted in viable mice with almost no expression of PC5/6 in small intestine, but with no overt phenotype. The data showed that by themselves ApcMin/+ tumors express lower levels of PC5/6 mRNA, and that the lack of PC5/6 in enterocytes results in a significantly higher tumor number in the duodenum, with a similar trend in other intestinal segments. Finally, the absence of PC5/6 is also associated with a premature mortality of ApcMin/+ mice.
  
  
  CONCLUSIONS
  Overall, these data suggest that intestinal PC5/6 is protective towards tumorigenesis, especially in mouse duodenum, and possibly in human colon.
authors.affiliation: Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, affiliated to the University of Montreal, Montreal, Quebec, Canada. sunx@ircm.qc.ca
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Sun
authors.forename: Rachid
authors.initials: R
authors.lastname: Essalmani
authors.forename: Nabil G
authors.initials: NG
authors.lastname: Seidah
authors.forename: Annik
authors.initials: A
authors.lastname: Prat
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics; D000818:Animals; D004195:Disease Models, Animal; D004386:Duodenum / Q000378:metabolism / Q000473:pathology; D020895:Enterocytes / Q000166:cytology / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007413:Intestinal Mucosa / Q000378:metabolism; D007414:Intestinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D007422:Intestines / Q000473:pathology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D045702:Proprotein Convertase 5 / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D018809:Proliferating Cell Nuclear Antigen; D045702:Proprotein Convertase 5; C473805:propeptide convertase 5, mouse