Objective： To investigate the enhancive effect ofN, N′-dinitrosopiperazine （DNP） on induced carcinogenesis in nasal and/or nasopharyngeal epithelia among TgN（p53mt-LMP1）/HT transgenic mice to examine the underly...Objective： To investigate the enhancive effect ofN, N′-dinitrosopiperazine （DNP） on induced carcinogenesis in nasal and/or nasopharyngeal epithelia among TgN（p53mt-LMP1）/HT transgenic mice to examine the underlying mechanism for the development of nasopharyngeal carcinoma （NPC）. Methods： TgN（p53mt-LMP1）/HT transgenic mice and the same strain of C57BL/6J wild-type mice both at the age of 5 months were randomly divided into 2 groups in parallel, respectively, i.e., TgN（p53mt-LMP1）/HT cancerous lesion-inducing group （T1）, TgN（p53mt-LMP1）/HT control group （TC）, C57BL/6J cancerous lesion-inducing group （CI）, and C57BL/6J control group （CC）. TI and CI mice were treated only with DNP for 16 weeks, twice each week, while TC and CC mice were given the same volume of saline as controls.At the end of treatment, animals were sacrificed to collect epithelial tissue samples from nasal cavity and nasopharynx for pathohistological evaluation by hacmatoxylin and eosin （HE） staining and for determination on the expression ofTRAF2, c-Jun, and p 16 by immunohistochemistry. Results： Atypical hyperplasia was more significant in the samples of TI than in those of TC, CI, and CC, with the rates of lesions being 90%, 10%, 0, and 0 （P〈0.01） respectively, though DNP was used alone in a much shortened inducing period at less dosage and without the use of carcinogenic promoter 12-0-tetradecanoylphorbol-13-acetate as usual. The expressions of tumor necrosis factor （TNF） receptor-associated factor 2 （TRAF2） and c-Jun in these samples were significantly up-regulated in TI （P〈0.0 I）, while tbe expression of p16 was significantly lower in TI than in the other groups （P〈0.01）. Conclusion： TgN（p53mt-LMPI）/HT mice hold inherited constitutional defect in immune surveillance function, which can be aggravated by environmental carcinogens, such as DNP used even though in a much less strength. The enhanced carcinogenesis-inducing effect of DNP on TgN（p53mt-LMP1）/HT mice should be closely associated with abnormal signaling of activator protein-1 （AP-1） pathway, especially up-regulated expressions of TRAF2 and c-Jun, and down-regulated expression of p l6.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 30672738, 30572455 and 30572408)Hunan Provincial Natural Science Foundation for Distinguished Young Scholars (No. 03JJY1006)+2 种基金for General Projects (Nos. 05JJ40029 and 07JJ6038)the Research Foundation of Hunan Provincial Scientific and Technological Department for International Cooperative Academic Projects (No. 06WK3016)the Research Foundation of Hunan Provincial Education Department for Outstanding Young Scholars (No. 06B070), China
文摘Objective： To investigate the enhancive effect ofN, N′-dinitrosopiperazine （DNP） on induced carcinogenesis in nasal and/or nasopharyngeal epithelia among TgN（p53mt-LMP1）/HT transgenic mice to examine the underlying mechanism for the development of nasopharyngeal carcinoma （NPC）. Methods： TgN（p53mt-LMP1）/HT transgenic mice and the same strain of C57BL/6J wild-type mice both at the age of 5 months were randomly divided into 2 groups in parallel, respectively, i.e., TgN（p53mt-LMP1）/HT cancerous lesion-inducing group （T1）, TgN（p53mt-LMP1）/HT control group （TC）, C57BL/6J cancerous lesion-inducing group （CI）, and C57BL/6J control group （CC）. TI and CI mice were treated only with DNP for 16 weeks, twice each week, while TC and CC mice were given the same volume of saline as controls.At the end of treatment, animals were sacrificed to collect epithelial tissue samples from nasal cavity and nasopharynx for pathohistological evaluation by hacmatoxylin and eosin （HE） staining and for determination on the expression ofTRAF2, c-Jun, and p 16 by immunohistochemistry. Results： Atypical hyperplasia was more significant in the samples of TI than in those of TC, CI, and CC, with the rates of lesions being 90%, 10%, 0, and 0 （P〈0.01） respectively, though DNP was used alone in a much shortened inducing period at less dosage and without the use of carcinogenic promoter 12-0-tetradecanoylphorbol-13-acetate as usual. The expressions of tumor necrosis factor （TNF） receptor-associated factor 2 （TRAF2） and c-Jun in these samples were significantly up-regulated in TI （P〈0.0 I）, while tbe expression of p16 was significantly lower in TI than in the other groups （P〈0.01）. Conclusion： TgN（p53mt-LMPI）/HT mice hold inherited constitutional defect in immune surveillance function, which can be aggravated by environmental carcinogens, such as DNP used even though in a much less strength. The enhanced carcinogenesis-inducing effect of DNP on TgN（p53mt-LMP1）/HT mice should be closely associated with abnormal signaling of activator protein-1 （AP-1） pathway, especially up-regulated expressions of TRAF2 and c-Jun, and down-regulated expression of p l6.
