TgN(p53mt_LMP1)/HT小鼠鼻腔和鼻咽黏膜上皮细胞增殖与凋亡相关基因表达的关系

背景与目的： 探讨TgN(p53mt_LMP1)/HT小鼠鼻腔和鼻咽黏膜上皮癌前病变发生与细胞周期分布，凋亡相关基因bax、bcl_2和增殖相关基因PCNA的表达水平及它们与p53mt基因表达的相关关系。 材料与方法： HE染色法观察G4代12月龄TgN(p53mt_LMP1)/HT转基因阳性和阴性小鼠鼻腔和鼻咽黏膜上皮病理组织学变化，流式细胞术测定细胞周期分布特点，免疫组织化学法检测组织中p53mt、bax、bcl_2和PCNA表达水平，综合分析其相关性。 结果： 转基因阴性小鼠和阳性小鼠鼻腔或鼻咽黏膜上皮癌前病变发生率分别为0和63.64％(P<0.01)。与转基因阴性小鼠比较，转基因阳性小鼠鼻腔和鼻咽黏膜上皮组织G0/G1期细胞数量减少，S期、G2/M期细胞数量增多，细胞增殖指数增高(P均<0.01)，p53mt、bcl_2和PCNA表达水平显著增高(P<0.01)，bax表达水平显著降低，bcl_2/bax比值升高(P<0.01)。 结论： TgN(p53mt_LMP1)/HT转基因阳性小鼠p53mt的表达可引起bax表达抑制，bcl_2表达水平增高，bcl_2/bax比值升高，PCNA表达增强，由此导致细胞凋亡活性降低，细胞增殖活性升高，细胞转化机率增加，可能与鼻腔或鼻咽黏膜上皮癌前病变有密切关系。

Association of Cell Proliferationin Nasal and NasopharyngealEpithelium with Expression ofApoptosis.related Genes inTgN(p53mt.LMP1) HT Mice

BACKGROUND AND AIM: To investigate the association of precancerous lesion development with cell cycle characteristics and expressive activities of genes such as bax,bcl-2 and PCNA and the relationship between these and p53mt expression in nasal and nasopharyngeal epithelia of TgN(p53mt-LMP1)/HT mice containing human mutant p53(p53mt) gene and EB virus latent membrane protein 1(LMP1).MATERIALS AND METHODS: The pathohistological changes in nasal and nasopharyngeal epithelial tissues in the fourth generation transgenic positive mice and negative mice aged 12 months were determined by H-E staining methods,cell cycle characteristics of nasal and nasopharyngeal epithelia were detected by flow cytometry,and expression activities of apoptosis-related genes such as p53mt,bax,bcl-2 and that of cell proliferation-related gene PCNA were assayed by immunohistochemistry in the same tissue samples.Then,a correlative analysis was carried out among the different sets of data to investigate the pathogenetic association of naturally developed precancerous lesion with the expression activities of apoptosis-and cell proliferation-related genes in the target organs.RESULTS: The rates of precancerous lesion in nasal and nasopharyngeal epithelia of positively transgenic mice and negative ones were 63.64% and 0 respectively,with very significant difference between them(P<0.01).Compared with that of negatively transgenic mice,the number of nasal or nasopharyngeal epithelial cells in G0/G1 phase was markedly decreased,and that in S and G2/M phases were obviously increased,with proliferation index(PI) enhanced significantly(P<0.01).The expression activities of p53mt,bcl-2 and PCNA were raised and that of bax was decreasedsignificantly,with an increased ratio of bcl-2/bax(P<0.01).CONCLUSION: The expression of p53mt in TgN(p53mt-LMP1)/HT mice may cause the inhibition of bax expression at first,followed by the increased expression of bcl-2 and PCNA,with an elevated ratio of bcl-2/bax.Thereafter,the activity of apoptosis would be reduced and cellular proliferating potentiality strengthened,as measured by PI.As a result,precancerous lesion may occur in nasal and/or nasopharyngeal epithelium.