BMC Cancer Research article Cyclophilin C-associated protein (CyCAP) knock-out mice spontaneously develop colonic mucosal hyperplasia and exaggerated tumorigenesis after treatment with carcinogen azoxymethane1 Emina Emilia Torlakovic*1, Vicki Keeler3, Chang Wang1, Hyun J Lim2, Leslie Ann Lining1 and Suzanne Laferté3 BioMed Central Open Access Address: 1Department of Pathology, Royal University Hospital, College of Medicine, University of Saskatchewan, Saskatoon, Canada, 2Department of Community Health & Epidemiology, University of Saskatchewan, Saskatoon, Canada and 3Department of Biochemistry, University of Saskatchewan, Saskatoon, Canada Email: Emina Emilia Torlakovic* - emt323@mail.usask.ca; Vicki Keeler - vicki.keeler@usask.ca; Chang Wang - chw263@mail.usask.ca; Hyun J Lim - hyun.lim@usask.ca; Leslie Ann Lining - lgl229@mail.usask.ca; Suzanne Laferté - suzanne.laferte@usask.ca * Corresponding author Published: 24 July 2009 BMC Cancer 2009, 9:251 doi:10.1186/1471-2407-9-251 This article is available from: http://www.biomedcentral.com/1471-2407/9/251 Received: 22 November 2008 Accepted: 24 July 2009 © 2009 Torlakovic et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: The discovery of a "serrated neoplasia pathway" has highlighted the role of hyperplastic lesions of the colon as the significant precursor of colorectal adenocarcinoma. In mice, hyperplasia of the colonic mucosa is a regular phenomenon after a challenge with colonic carcinogens indicating that mucosal hyperproliferation and thickening, even without cytological dysplasia, represents an early pre-malignant change. Cyclophilin C-associated protein (CyCAP) has been described to down-modulate endotoxin signaling in colorectal murine mucosa and is a murine orthologue of the tumor-associated antigen 90 K (TAA90K)/mac-2-binding protein. Methods: Female Balb/c wild-type (WT) and CyCAP knock-out (KO) mice (6–8 weeks old) were administered 2 or 6 weekly subcutaneous injections of azoxymethane. The animals were evaluated post-injection at six weeks for aberrant crypt foci (ACF) study and at five months for colon tumor measurement. The thickness of the colon crypts was measured in microns and the number of colonocytes per crypt was also determined in well-oriented crypts. Morphometric analyses of the colon mucosa were also performed in untreated 6–8 weeks old KO and WT animals. Formalin- fixed/paraffin-embedded colon sections were also studied by immunohistochemistry to determine the Ki-67 proliferation fraction of the colon mucosa, β-catenin cellular localization, cyclin D1, c- myc, and lysozyme in Paneth cells. Results: Cyclophilin C-associated protein (CyCAP)-/- mice, spontaneously developed colonic mucosal hyperplasia early in life compared to wild-type mice (WT) (p < 0.0001, T-test) and crypts of colonic mucosa of the (CyCAP)-/- mice show higher proliferation rate (p = 0.039, Mann-Whitney Test) and larger number of cyclin D1-positive cells (p < 0.0001, Mann-Whitney Test). Proliferation fraction and cyclin D1 expression showed positive linear association (p = 0.019, Linear-by-Linear Association). The hyperplasia was even more pronounced in CyCAP-/- mice than in WT after challenge with azoxymethane (p = 0.005, T-test). The length of the crypts (r = 0.723, p = 0.018, Spearman Correlation) and the number of colonocytes per crypt (r = 0.863, p = 0.001, Spearman Correlation) in non-tumorous areas were positively associated with azoxymethane-induced Page 1 of 11 (page number not for citation purposes)