Establishment and in vivo imaging observation of a nude mouse model of type 2 diabetes mellitus and pancreatic cancer / 临床肝胆病杂志

ABSTRACT

ObjectiveTo establish a nude mouse model of type 2 diabetes mellitus （T2DM） and pancreatic cancer that allows dynamic observation of tumor formation process and facilitates in vivo research. MethodsAt first， human pancreatic cancer PANC-1 cells were transfected with lentiviral vector GV260 to construct the pancreatic cancer cell line PANC-1-Luc with stable expression of firefly luciferase. Then， 36 specific pathogen-free nude mice were randomly divided into control group with 12 mice and model group with 24 mice （nude mice with T2DM and pancreatic cancer）. The mice in the control group were fed with breeding diet and were then given ectopic subcutaneous implantation of PANC-1-Luc cells， and those in the model group were first given high-fat diet and intraperitoneal injection of 1% STZ， followed by ectopic subcutaneous implantation of PANC-1-Luc cells. The fluorescence in vivo imaging system and the manual measurement method were used for simultaneous and dynamic monitoring of the growth of pancreatic cancer in nude mice in the two groups， and the tumor growth curve was plotted to investigate the correlation between fluorescence value and tumor volume. Subcutaneous tumors and pancreatic islets were observed under a microscope to verify whether the model was successfully established， and immunohistochemistry was used to measure the expression of Ki-67 in tumor tissue to investigate the influence of hyperglycemia on the growth of pancreatic cancer in nude mice. The independent-samples t test was used for comparison of normally distributed continuous data between groups， and the Mann-Whitney U test was used for comparison of non-normally distributed continuous data between groups. ResultsThe optimal virus titer was determined as 5×107 TU/mL for the stable transfection of lentiviral vector in PANC-1 cells， and the optimal concentration selected with puromycin was 20 μg/mL， with an optimal selection time of 9 days. The fluorescence value of PANC-1-Luc cells was linearly and positively correlated with the number of cells， with the linear equation of y=42.56x－42 504 （r=0.977， P=0.004）. The blood glucose value of T2DM nude mice was 23.05 （19.25‍ — ‍26.40） mmol/L， with a blood glucose level of >11.1 mmol/L in each nude mouse， and there was a significant difference in blood glucose value between the T2DM nude mice and the control nude ［6.15 （5.20‍ — ‍7.30） mmol/L］ （Z=-8.45， P<0.001）. Compared with the control group， the model group had reductions in the number and volume of pancreatic islets， with irregular shapes and unclear boundaries， and pathological examination confirmed that the xenograft tumor was pancreatic cancer tissue， which showed that the model was established successfully. In the model group， there was a linear positive correlation between subcutaneous tumor size and fluorescence values， with the linear equation of y=232 348 691x－8 258 608 （r=0.911， P=0.031）. The model group had a significantly higher positive rate of Ki-67 than the control group （50.333%± 7.808% vs 15.917%±4.055%， t=13.55， P<0.001）， suggesting rapid tumor proliferation in the model group. ConclusionThe T2DM nude mouse model of pancreatic cancer established in this study can simulate the pathological process of the development and progression of pancreatic cancer in the context of T2DM and dynamically observe the influence of hyperglycemia on the growth of pancreatic cancer cells in vivo， thereby providing a new experimental vector for the in vivo study of the development and progression of pancreatic cancer in the context of T2DM.