Development of ApcloxP/loxP+ KrasLSL-G12D- transgenic mouse model for human sporadic colorectal cancer

Abstract

Objective To construct ApcloxP/loxP+ KrasLSL-G12D/- double transgenic mouse model that can simulate the occurrence and development of human sporadic colorectal cancer. Methods The Apctm1Tyj/J (ApcloxP) and B6.129S4-Krastm4Tyj/J (KrasLSL-G12D) mice were purchased from Jackson Laboratory, and their genotypic milieu were transformed into C57BL/6J mice and then crossed to establish a transgenic mouse strain. The genotypes of mice were discerned by polymerase chain reaction (PCR) and fluorescence quantitative PCR. Finally, double transgenic mice with ApcloxP/loxP+ KrasLSL-G12D/- genotype were bred. Mice were divided into two groups: C57BL/6J mice group (n=10) and ApcloxP/loxP+ KrasLSL-G12D/- mice group (n=10). Lentivirus which can express Cre recombinant enzyme and Luciferase, were injected into the intestinal mucosa of mice under colonoscopy (FB-8V, Japan PENTAX company). The tumorigenesis of the mice can be observed dynamically by in vivo Imaging System (IVIS). The tumor tissues of the mice were sampled and stained with Hematoxylin-Ehong (HE) to verify the tumorigenicity of the mice. The difference of the two groups was compared with t test. Results 24 ApcloxP/loxP+ KrasLSL-G12D/- mice were successfully bred. The age of mice in the experimental group and control group was (62±2) days and (63±2) days, respectively, with no statistically significant difference (t=0.343, P>0.05). The body mass of the two groups was (21.39±1.40) g and (22.35±1.37) g, respectively, with no statistically significant difference (t=0.682, P>0.05). Lentivirus was injected into the intestinal mucosa of mice shaping colorectal cancer. At the end of 12 weekend, 4 of 10 mice (tumorigenesis rate were 40%) in ApcloxP/loxP+ KrasLSL-G12D/- group were found burden colorectal adenocarcinoma confirmed by IVIS and histology. However, tumor lesion was not observed in all C57BL/6J mice. Conclusion In this study, the colorectal carcinogenesis of ApcloxP/loxP+ KrasLSL-G12D/- transgenic mice were induced by Lentivirus expressing Cre enzyme, which successfully imitated the germination and development of human sporadic colorectal cancer. Key words: Colorectal cancer; Apc gene; Kras gene; Models; Mice