Comparison of dose-dependent enhancing effects of ?-ray irradiation on urethan-induced lung tumorigenesis in athymic nude (nu/nu) mice and euthymic (nu/+) littermates

Autor: Sadayoshi Kobayashi, H Otsu, Y Noda, T Ogiu
Rok vydání: 1996
Předmět:
Zdroj: Journal of Cancer Research and Clinical Oncology. 122:231-236
ISSN: 1432-1335
0171-5216
DOI: 10.1007/bf01209651
Popis: The role of immunological surveillance in carcinogenesis is still controversial. In our previous experiments, urethan-induced lung tumorigenesis in athymic (nu/nu) mice and euthymic (nu/+) littermates was examined, and it was concluded that immunosurveillance mediated by T cells could not be demonstrated. However, the reported enhancement of development of various tumors following ionizing radiation might be achieved through modulating the host immunological conditions. In the present experiment,nu/nu and littermatenu/+ mice were treated with 1–4 Gy γ-rays alone at 6 weeks of age or treated with urethan at 0.5 mg/g body weight when aged 14 days followed by 1–4 Gy γ-rays 4 weeks later. Lung tumors were assessed at 6.5 months of age. Ionizing radiation itself caused a very low incidence of these lesions. On the other hand, multiplicities and incidences of lung tumors after urethan treatment at 0.5 mg/g body weight were similar between the two phenotypically different groups of mice (1.66 and 1.84 tumors/mouse, 73% and 80% incidences, fornu/nu andnu/+ cases respectively). This urethan-induced lung tumorigenesis was significantly enhanced by γ-rays in bothnu/nu andnu/+ mice, and the magnitude of tumor enhancement was somewhat higher innu/+ mice than innu/nu mice, especially with a 2-Gy dose. In conclusion, it may be said that lung tumorigenicity of γ-ray irradiation itself and the enhancing effect of radiation on urethan-induced tumorigenesis are scarcely influenced by immunosurveillance mechanisms mediated by T cells
Databáze: OpenAIRE
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