The oncogenic potential of a mutant TP53 gene explored in two spontaneous lung cancer mice models

Abstract

Background: Lung cancer is the number one cancer killer worldwide. A major drawback in the lung cancer treatment field is the lack of realistic mouse models that replicate the complexity of human malignancy and immune contexture within the tumor microenvironment. Such models are urgently needed. Mutations of the tumor protein p53 are among the most common alterations in human lung cancers.

Methods: Previously, we developed a line of lung cancer mouse model where mutant human TP53-273H is expressed in a lung specific manner in FVB/N background. To investigate whether the human TP53 mutant has a similar oncogenic potential when it is expressed in another strain of mouse, we crossed the FVB/N-SPC-TP53-273H mice to A/J strain and created A/J-SPC-TP53-273H transgenic mice. We then compared lung tumor formation between A/J-SPC-TP53-273H and FVB/N-SPC-TP53-273H.

Results: We found the TP53-273H mutant gene has a similar oncogenic potential in lung tumor formation in both mice strains, although A/J strain mice have been found to be a highly susceptible strain in terms of carcinogen-induced lung cancer. Both transgenic lines survived more than 18 months and developed age related lung adenocarcinomas. With micro CT imaging, we found the FVB-SPC-TP53-273H mice survived more than 8 weeks after initial detection of lung cancer, providing a sufficient window for evaluating new anti-cancer agents.

Conclusions: Oncogenic potential of the most common genetic mutation, TP53-273H, in human lung cancer is unique when it is expressed in different strains of mice. Our mouse models are useful tools for testing novel immune checkpoint inhibitors or other therapeutic strategies in the treatment of lung cancer.

Keywords: Immunotherapy; Lung cancer; Mouse model; TP53 mutation.

Fig. 1

Schematic diagram of creation of the SP-C/p53-273H transgenic mouse. A 1.8-kb human mutant p53-273H cDNA (arginine to histidine substitution at codon 273) was placed under the transcriptional control of a 3.7-kb region of the human SP-C promoter. Transgenic mice were generated by microinjection of a total of 6.7-kb XhoI fragment of the SP-C/p53-273H construct into the pro-nuclei of FVB/N mouse zygotes by standard methods

Fig. 2

Lung tumor formation in the A/J-SPC-TP53-273H transgenic mice and non-transgenic mice at ages 7–18 months respectively

Fig. 3

Lung Tumor Rate in FVB/N-SPC-TP53-273H and A/J-SPC-TP53-273H mice. a FVB/N-SPC-TP53-273H and A/J-SPC-TP53-273H mice were sacrificed and analyzed for lung tumor incidence. The rate of tumor formation is shown here in both strains. The A/J-SPC-TP53-273H transgenic mice have an increased rate of lung tumor in all age groups when compared to the FVB/N-SPC-TP53-273H mice. The tumor rate change between both groups is represented by the error bar. b Lung tumor rate observed in A/J non-transgenic (A/J-NT) mice and FVB/N non-transgenic (FVB/N-NT) mice. At age of 13–15 and 16–18 months A/J- NT mice had a more frequent tumor rate when compared to FVB/N-NT mice

Fig. 4

Spontaneous lung tumor development in three FVB/N-SPC-TP53-273H mice over 7 weeks. Three mice were followed over a total time of 7 weeks and analyzed for lung tumor growth at week 1 (initial), week 3 and week 7 via micro CT imaging. The tumor volume progress was recorded from initial to week 7 in three selected mice. The fold change in tumor volume between initial and week 7 is depicted by the error bars for mice 1, 2 and 3

Fig. 5

Lung tumor growth over time assessed by micro CT. Micro CT images were taken from a FVB/N-SPC-TP53-273H transgenic mouse and followed over a period of 7 weeks. a Initial scan of a mouse lung showing a single tumor with diameter of 1.77 mm. b Lung tumor increasing in size to about 2.35 mm in diameter at week 4. c At week 7 tumor size was observed to be 3.14 mm

Fig. 6

Histopathology of lung cancer in two lines of transgenic mice. a H&E staining of an invasive adenocarcinoma from an A/J-SPC-TP53-273H mouse, b immunohistochemical detection of human mutant p53-273H expression in a murine lung adenocarcinoma collected from an A/J-SPC-TP53-273H mouse. The antibody used was an anti-human specific p53 antibody (DO-7), c H&E staining of an adenocarcinoma from an A/J-SPC-TP53-273H mouse at high magnification (400X), and d H&E staining of an adenocarcinoma from an FVB/N-SPC-TP53-273H mouse at high magnification (400X)