P3.01-053 Mouse Models of Primary Lung Cancer - A Thorough Evaluation: Topic: Models of Lung Cancer

Abstract

Lung cancer is the most prominent cancer in human with the highest mortality rate among cancer patients in both genders nowadays. Several models of primary lung cancer research are in use, however, no systematic evaluation of optimal models is available. Here, we assess and reappraise the most robust models of primary lung cancer for their suitability of cancer evolution and targetability for new therapeutics. Three models of primary lung cancer were evaluated: (I) Carcinogen (urethane or diethylnitrosamine (DEN)) induced lung cancer model, established via three intraperitoneal (i.p.) injections to BALB/c and C57BL/6 mouse strains. Five and ten months after injections, mice were assessed for tumor incidence. Lewis Lung Carcinoma (LLC) cell line was employed for an orthotopic development of lung tumor in syngeneic mouse. The cell line was injected (II) intravenously (i.v.) or (III) subcutaneously (s.c.) to establish lung tumor models in 14 days. Tumor nodules and tumor necrosis were confirmed by microscopy. Immunohistochemistry (IHC) of markers of proliferation (p-Histone3, inhibitor of differentiation 1 (Id1), and Ki67), immune cells (CD4, CD8, B220, F4/80, and NKp46), vascular structure (CD31), stroma (alpha-actin) were performed for a finer characterization of the tumor. Ten months after i.p. injections of carcinogens, we found that the urethane model stably induced tumor nodules (90%: 9/10) when compared to DEN (30%: 3/10). BALB/c strain was significantly more susceptible for the urethane induced tumor development compared to C57BL/6 strain. Injection of LLC cell line via i.v. developed diffuse lung tumor without metastasis to other organs. s.c. injection also stably developed single tumor nodule (∼500mg). IHC revealed that all tumors were consistently positive for the proliferation markers, and F4/80+ cells and CD4+ cells infiltrated into tumors significantly more than CD8+, B220+, or NKp46+ cells. Heterogeneous distributions of CD31+ cells and alpha-actin+ cells were observed in overall tumor models. The urethane-induced lung tumor is reliable and reproducible with a high rate of development and seems superior to DEN induced tumor, but need a long time period to develop. In contrast, the i.v. and s.c. tumor models are established within short time ranges. The tumors developed by s.c. enable for the analysis of the tumor only without adjacent tissue bias. The involvement and characteristics of immune cells found within tumors were comparable across all models. Injections by i.v. or s.c. of cell line to mouse can be considered as an alternative yet convenient model to develop various different types of lung cancers.