Winnie- APCMin/+ Mice: A Spontaneous Model of Colitis-Associated Colorectal Cancer Combining Genetics and Inflammation

Abstract

(1) Background: Colorectal cancer (CRC) is among the best examples of the relationship between inflammation and increased cancer risk. (2) Methods: To examine the effects of spontaneous low-grade chronic inflammation on the pathogenesis of CRC, we developed a new murine model of colitis-associated cancer (CAC) by crossing Mucin 2 mutated mice (Winnie) with Apc^Min/+ mice. (3) Results: The resulting Winnie-Apc^Min/+ model combines an inflammatory background with a genetic predisposition to small intestinal polyposis. Winnie-Apc^Min/+ mice show an early occurrence of inflammatory signs and dysplastic lesions in the distal colon with a specific molecular signature. (4) Conclusion: The Winnie-Apc^Min/+ model is a perfect model to demonstrate that chronic inflammation represents a crucial risk factor for the onset and progression of tumoral lesions in individuals genetically predisposed to CRC.

Keywords: Aberrant Crypt Foci; colorectal cancer; inflammation; murine model.

Figure 1

Creation and characterization of the Winnie-APC^Min/+ murine model. (A) Breeding strategy used to obtain Winnie-APC^Min/+ mice and the control littermates. (B) Impact of APC^Min/+ mutation on survival rate in the breeding scheme of Winnie and Winnie-APC^Min/+ mice. (C) Body weight analysis of 4-week-old Winnie-APC^Min/+ mice and their relative controls. (D–F) Representative images of colon (D) and data analysis of colon length, and (E) colon length adjusted to body weight (F) for Winnie-APC^Min/+ mice and control lines sacrificed at 5 weeks. (E,F): n = 7 animals/group. * p < 0.05, *** p < 0.001 compared to WT mice.

Figure 2

Hematoxylin and eosin staining on 3μm colon sections from proximal (A), medial (B) and distal (C) tracts of 5-week-old Winnie-APC^Min/+ mice. Images were captured at 10× (left) and 20× magnifications (right).

Figure 3

PAS staining on 3 μm sections from distal colon of 5-week-old WT (A), Winnie (B), APC^Min/+ (C) and Winnie-APC^Min/+ (D) mice. Images were captured at 20× magnification.

Figure 4

Molecular pathways activated in 5-week-old Winnie-APC^Min/+ mice. The distal colon of Winnie-APC^Min/+ mice (white bars) was analyzed by qPCR relative to Winnie (A) and APC^Min/+ (B) mice (black bars) (n = 3–4 animals/group). Horizontal lines indicate common genes between the two comparisons. Histograms represent the mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001.

Figure 5

Histological analysis of 8-week-old Winnie-APC^Min/+ mice. (A) Hematoxylin and eosin staining on 3μm distal colon sections. Images were captured at 10× (left) and 20× magnifications (right). (B) Dot plot shows CRC progression from 5 to 8 weeks for Winnie-APC^Min/+ mice as mean ± SEM of dysplastic ACFs. (C) Histograms show dysplastic ACFs composition in terms of dimension and grading for Winnie-APC^Min/+ mice at 5 and 8 weeks. 5-week: n = 8–10 animals/group; 8-week: n = 8 animals/group. *p < 0.05.