Lentivirus‐mediated somatic recombination and development of a novel mouse model for sporadic colorectal cancer

Abstract

In this study, we have developed a novel mouse model for sporadic colorectal cancer (CRC) by utilizing APC conditional knockout (Apc(CKO) ) mouse and lentivirus encoding Cre recombinase and a reporter gene (EGFP or LacZ). Lentiviral transduction of colonic crypt stem cells allowed for the long-term expression of reporter gene as well as excision of floxed Apc alleles, which resulted in tumor development. Tumors represented adenoma stages along with the nuclear accumulation of β-catenin. Loss of E-cadherin at the cellular junctions and strong expression of Vimentin suggested the sign of active epithelial-mesenchymal transition. Moreover, nuclear staining of Ki67 inside epithelial cells of aberrant crypts demonstrated their higher proliferative nature. Erratic downstream signaling of activated Wnt/β-catenin, AKT/mTOR, and Notch pathways provided strong evidence towards the higher proliferative index of epithelial cells inside the aberrant crypts. These results do recapitulate the findings of previous APC mutant mouse models. Our model represents sporadic CRC more precisely as (i) tumors result from somatic mutations but not from germline; (ii) tumors develop in colon not in small intestine; (iii) few tumors develop at the distal end of colons. Additionally, our model allows for the long-term expression of the gene(s), which get integrated into the host cell genome and provides an ability to track the tumor growth. © 2016 Wiley Periodicals, Inc.

Characteristics of Differently Located Colorectal Cancers Support Proximal and Distal Classification: A Population-Based Study of 57,847 Patients

“…Furthermore, DSS was significantly worse in patients with RCC than in patients with distal CRC in the subgroups of patients who had stage III or IV disease, were 70 years or younger, or had non-mucinous adenocarcinoma. The predictive value of primary tumor location in survival among patients with metastatic CRC was confirmed in several latest studies[25–28]. Chen et al revealed that right-sided tumor site was an independent predictor of shorter PFS (HR = 1.32, P = 0.0072) and OS (HR = 1.45, P = 0.0003) among 969 patients with KRAS wild-type CRC receiving Cetuximab therapy treatment[26].…”

Jagged-2 (JAG2) enhances tumorigenicity and chemoresistance of colorectal cancer cells

“…We recently reported that JAG2 expression is up-regulated in colorectal tumors of Apc CKO mice resulting from transduction of colonic epithelium with Cre-encoding lentivirus [ 15 ]. To determine JAG2 expression in other mouse models of CRC, we analyzed JAG2 expression in the intestinal tumors of Apc Min /+ mice.…”

“…Constitutive activation of β-catenin signaling due to inactivating mutations in APC gene or activating mutations in β-catenin gene is a common feature of CRC. We previously have shown that JAG2 expression is increased in colorectal tumors of Apc CKO mice [ 15 ]. In the current study, we also observed increased JAG2 mRNA expression in the tumors of Apc Min /+ mice, while tumoral expression of other NOTCH ligands was variable.…”

“…Additionally, NOTCH signaling increases chemoresistance by protecting tumor cells from apoptosis [ 11 – 14 ]. We recently reported a novel mouse model of sporadic CRC using conditional Apc knockout (Apc CKO ) mice, in which intra-rectal administration of Cre-encoding lentivirus resulted in stochastic transduction of colonic epithelium, leading to the inactivation of floxed Apc gene and subsequent tumor development [ 15 ]. High levels of NICD and HES1 expression were observed in the developed tumors, suggesting activation of NOTCH signaling.…”

TRIM29 is differentially expressed in colorectal cancers of different primary locations and affects survival by regulating tumor immunity based on retrospective study and bioinformatics analysis

“…The difference in prognosis among RCC, LCC, and RECC patients is notable, with most studies confirming that RCC patients have poorer prognosis compared to patients with LCC and RECC (5,14,(18)(19)(20). Furthermore, the intestinal flora, clinical manifestations, and treatment responses of patients with RCC, LCC, and RECC vary considerably (18,19).…”