Differential Effects of Trp53 Alterations in Murine Colorectal Cancer.

Alexander M Betzler,Sebastian Schölch,Moritz Jesinghaus,Jürgen Weitz,Michael H Muders,Janine Roy,Barbara Klink,Nuh N Rahbari,Massimiliano Mazzone,Wilko Weichert,Katja Steiger,Matthias Kloor,Lahiri K Nanduri,Linda Blickensdörfer,Christoph Reissfelder,Michael Schroeder,Barbara Hissa

doi:10.3390/cancers13040808

Abstract

Simple SummaryAlthough colorectal cancer is among the most frequent malignant tumors, there are currently no mouse models available that reliably mimic both tumor biology as well as treatment response. In this article, we describe a novel mouse model in which mutations relevant to colorectal cancer are induced in mice, leading to tumor formation in the distal colon. The tumors are monitored via colonoscopy, and the survival and the histology of the tumors are examined. We demonstrate that this model can closely model the human disease clinically, histologically and genetically. In addition, the response of this model to classical colorectal cancer treatments is more realistic than that of other mouse models. The effects of different mutations in the Trp53 gene on tumor cells show striking differences, similar to the effects in other tumor diseases. In summary, the new model allows more accurate and predictive experiments in colorectal cancer.Background: Colorectal cancer (CRC) development is a multi-step process resulting in the accumulation of genetic alterations. Despite its high incidence, there are currently no mouse models that accurately recapitulate this process and mimic sporadic CRC. We aimed to develop and characterize a genetically engineered mouse model (GEMM) of Apc/Kras/Trp53 mutant CRC, the most frequent genetic subtype of CRC. Methods: Tumors were induced in mice with conditional mutations or knockouts in Apc, Kras, and Trp53 by a segmental adeno-cre viral infection, monitored via colonoscopy and characterized on multiple levels via immunohistochemistry and next-generation sequencing. Results: The model accurately recapitulates human colorectal carcinogenesis clinically, histologically and genetically. The Trp53 R172H hotspot mutation leads to significantly increased metastatic capacity. The effects of Trp53 alterations, as well as the response to treatment of this model, are similar to human CRC. Exome sequencing revealed spontaneous protein-modifying alterations in multiple CRC-related genes and oncogenic pathways, resulting in a genetic landscape resembling human CRC. Conclusions: This model realistically mimics human CRC in many aspects, allows new insights into the role of TP53 in CRC, enables highly predictive preclinical studies and demonstrates the value of GEMMs in current translational cancer research and drug development.

Highlights

Colorectal cancer (CRC) is genetically a highly heterogeneous disease [1]
CRC evolution starts with mutations in the APC gene [2], often followed by oncogenic KRAS and TP53 mutations [3]
We evaluated the differential effects of various genetic alterations in the Trp53 gene in CTC

Summary

Introduction

Colorectal cancer (CRC) is genetically a highly heterogeneous disease [1]. CanonicalCRC evolution starts with mutations in the APC gene [2], often followed by oncogenic KRAS and TP53 mutations [3]. Most currently used CRC mouse models are based on the subcutaneous or orthotopic injection of cell lines into immunodeficient or, in the case of murine cell lines, immunocompetent mice [6,7,8,9] This results in anaplastic tumors that typically respond well to cytotoxic therapy and may overestimate the efficacy of novel compounds [10]. The only currently known GEMM of sporadic (i.e., unifocal) CRC employs segmental cre-recombination in the colon via surgical clamping and infection with adeno-cre virus [18,19,20] In this model, mice with conditional mutations of Apc and Kras and other oncogenes are segmentally infected and subsequently develop one or few adenomas of the distal colon, eventually invasive carcinoma and rarely metastatic disease. Conclusions: This model realistically mimics human CRC in many aspects, allows new insights into the role of TP53 in CRC, enables highly predictive preclinical studies and demonstrates the value of GEMMs in current translational cancer research and drug development

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