Original Research
Mouse Model of Mutated in Colorectal Cancer Gene Deletion Reveals Novel Pathways in Inflammation and Cancer

https://doi.org/10.1016/j.jcmgh.2019.01.009Get rights and content
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open access

Background & Aims

The early events by which inflammation promotes cancer are still not fully defined. The MCC gene is silenced by promoter methylation in colitis-associated and sporadic colon tumors, but its functional significance in precancerous lesions or polyps is not known. Here, we aimed to determine the impact of Mcc deletion on the cellular pathways and carcinogenesis associated with inflammation in the mouse proximal colon.

Methods

We generated knockout mice with deletion of Mcc in the colonic/intestinal epithelial cells (MccΔIEC) or in the whole body (MccΔ/Δ). Drug-induced lesions were analyzed by transcriptome profiling (at 10 weeks) and histopathology (at 20 weeks). Cell-cycle phases and DNA damage proteins were analyzed by flow cytometry and Western blot of hydrogen peroxide–treated mouse embryo fibroblasts.

Results

Transcriptome profiling of the lesions showed a strong response to colon barrier destruction, such as up-regulation of key inflammation and cancer-associated genes as well as 28 interferon γ–induced guanosine triphosphatase genes, including the homologs of Crohn’s disease susceptibility gene IRGM. These features were shared by both Mcc-expressing and Mcc-deficient mice and many of the altered gene expression pathways were similar to the mesenchymal colorectal cancer subtype known as consensus molecular subtype 4 (CMS4). However, Mcc deletion was required for increased carcinogenesis in the lesions, with adenocarcinoma in 59% of MccΔIEC compared with 19% of Mcc-expressing mice (P = .002). This was not accompanied by hyperactivation of β-catenin, but Mcc deletion caused down-regulation of DNA repair genes and a disruption of DNA damage signaling.

Conclusions

Loss of Mcc may promote cancer through a failure to repair inflammation-induced DNA damage. We provide a comprehensive transcriptome data set of early colorectal lesions and evidence for the in vivo significance of MCC silencing in colorectal cancer.

Keywords

E2F Targets
DNA Repair
IFNγ-Induced GTPases
CMS4

Abbreviations used in this paper

AHR
aryl hydrocarbon receptor
BrdU
bromodeoxyuridine
CAC
colitis-associated cancer
cDNA
complementary DNA
CHK
checkpoint kinase
CMS4
consensus molecular subtype 4
DSS
dextran sodium sulfate
EMT
epithelial mesenchymal transition
F
forward
GSEA
gene set enrichment analysis
GTPase
guanosine triphosphatase
γH2AX
gamma histone 2AX
IBD
inflammatory bowel disease
IFNγ
interferon γ
KD
knockdown
KO
knockout
MCC
mutated in colorectal cancer
MEF
mouse embryo fibroblast
MMR
mismatch repair
NT
nontargeted
qPCR
quantitative polymerase chain reaction
R
reverse
RB
retinoblastoma
SSB
DNA single-strand break
UPL
Universal Probe Library
WT
wild type

Cited by (0)

Author contributions Maija Kohonen-Corish was responsible for the study concept and design and obtained funding; Nicola Currey, Zeenat Jahan, C. Elizabeth Caldon, Phuong Tran, Fahad Benthani, Penelope De Lacavalerie, Daniel Roden, Brian Gloss, Claudia Campos, Elaine Bean, Amanda Bullman, Saskia Reibe-Pal, and Jane Dahlstrom acquired, analyzed, and interpreted data and performed the statistical analysis; Maija Kohonen-Corish, Jane Dahlstrom, and C. Elizabeth Caldon drafted the manuscript and critically revised the manuscript for important intellectual content; and Marcel Dinger, Mark Febbraio, and Stephen Clarke provided material support or resources.

Conflicts of interest The authors disclose no conflicts.

Funding Supported by the Cancer Council New South Wales (RG17-05), National Health and Medical Research Council (1020406 and 1075149), Cancer Institute New South Wales (10CDF232), Gastroenterological Society of Australia, Sydney Catalyst, Royal Australasian College of Surgeons, and the Colorectal Surgical Society of Australia and New Zealand. The contents of the published material are solely the responsibility of the administering institution, a participating institution, or individual authors and do not reflect the views of the National Health and Medical Research Council. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Authors share co-first authorship.