Protocol to establish an accelerated murine model for Helicobacter-induced gastric cancer

Abstract

Helicobacter-induced gastric cancer progresses very slowly, even in animal models, making it difficult to study. Here, we present a protocol to establish an accelerated murine model for Helicobacter-induced gastric cancer. We describe steps for infecting mice with Helicobacter felis, harvesting gastric tissue, assessing disease severity by histopathologic scoring, and performing gene expression studies with RT-qPCR and RNA sequencing. The accelerated model shows rapid progression of the disease, with gastric precancerous lesions developing within 6 months post-infection with Helicobacter. For complete details on the use and execution of this protocol, please refer to Bali et al.¹.

Keywords: Cancer; Microbiology; Model Organisms; Molecular Biology.

Graphical abstract

Figure 1

H. felis on Columbia agar The image shows H. felis growing as a lawn, not as individual distinct colonies.

Figure 2

Mouse infection timeline This illustration shows the timeline of inoculating WT and Myd88^−/− mice with H. felis by oral gavage at an interval of one day for a total of three inoculations. Uninfected mice serve as control for each genetic background. n = 8 mice /group.

Figure 3

Illustration of mouse stomach sections used for analyses At indicated time points mice are euthanized and stomachs are removed from the abdominal cavity. Each mouse stomach is opened by cutting along the greater curvature and laid flat on a petri plate. Then it is cut into longitudinal sections and processed for various analyses.

Figure 4

A paraffin embedded tissue section A stomach tissue section was paraffin embedded and cut on the edge for histopathology analysis.

Figure 5

Representative mice stomachs following infection with H. felis for 1, 3, or 6 months Mice stomachs exhibit thicker mucosa with larger folds that increase in thickness with time in Myd88^−/−-infected (accelerated model) compared to WT-infected (standard model) mice. n = 8 mice /group.

Figure 6

Histopathologic stages in mouse gastric tissue in response to H. felis infection WT and Myd88^−/− mice are infected with H. felis for 1, 3, or 6 months (8 mice /group). Representative mouse stomach tissue sections from WT and Myd88^−/− mice are shown (bar scale: 500 μm) (A). Mice stomachs are processed and scored double-blinded for histologic disease severity on an ascending scale from 0 (no lesions) to 4 (severe lesions) as described in our previous studies^, using criteria outlined by Rogers et al. (B). Histopathologic scores, which are a measure of disease severity^,,, show significant differences with increased disease in H. felis-infected Myd88^−/− mice (accelerated model) compared to H. felis-infected WT mice (standard model). ∗p < .05, ∗∗p < .01, ∗∗∗p < .001.