【作者】 周翠琦；

【导师】 徐宁志；

【作者基本信息】 中国协和医科大学 ， 细胞生物学， 2004， 博士

【摘要】 恶性肿瘤是一类极其复杂的疾病，具有以下基本特征：细胞周期紊乱，有丝分裂异常，细胞具有基因组不稳定性。因此，从某种意义上来说，恶性肿瘤是一类细胞周期疾病。 人垂体瘤转化基因hPTTG，又称Securin，是有丝分裂中期纺锤体检验点通路的重要成员。它监控细胞周期的有序进行，保障细胞分裂的忠实性和遗传的稳定性，并且参与恶性转化和肿瘤发生。我们克隆表达了hPTTG基因，发现它影响细胞周期、促进细胞生长、引起恶性转化。我们使用RT-PCR和原位杂交方法，在食管癌中检测到hPTTG的高表达，统计学分析表明hPTTG的高表达与肿瘤的分化和转移密切相关。进一步深入研究hPTTG的调节机制，发现β-catenin／TCF通路上调hPTTG的转录和表达，并且食管癌标本的检测证明β-catenin的胞浆累积与hPTTG的高表达正相关；此外，MAPK通路抑制剂可抑制hPTTG的转录和表达；γ-synuclein引起染色体不稳定性并上调hPTTG的表达，hPTTG可能参与γ-synuclein引起不稳定性的过程。hPTTG广泛地影响一些重要的肿瘤相关基因，它上调癌基因cyclinD1和抗凋亡基因survivin的表达，抑制Gsk3β的激酶活性，并与p53结合。 综上所述，hPTTG的功能极其复杂，它参与细胞周期调控，沟通庞大的信号通路网络。探讨和阐明它参与肿瘤发生发展的作用机制，不仅对深入认识细胞周期和人类肿瘤大有裨益，还具有潜在的临床应用前景。更多还原

【Abstract】 The malignant tumor is a complicated disease characterized with inordinate cell cycle, abnormal mitosis and genetic instability. In a certain sense, the malignant tumor is a kind of cell cycle diseases.Human pituitary tumor transforming gene (hPTTG), also termed as Securin, is a key molecular of mitotic spindle checkpoint pathway. hPTTG surveilles orderly progression of cell cycle, ensures the fidelity of cell division and genetic stability, and participates in malignant transformation and tumorigenesis. We cloned and expressed hPTTG, observed its influences on cell cycle, and found that it accelerated cell proliferation and promoted cell malignant transformation. We detected its overexpression in human esophageal tumor tissues compared with the corresponding normal tissues, by using RT-PCR assay and in situ hybridization. On the other hand, the statistical analysis revealed that overexpression of hPTTG was closely associated with tumor differentiation and lymph node metastasis. We further investigated hPTTG’s regulation mechanisms, demonstrated that β-catenin/TCF up-regulated hPTTG transcriptional avtivity and its expression. Subsequently, we detected the positive correlation between cytoplasmic accumulation of β-catenin and overexpression of hPTTG in 69 human esophageal tumors. Furthermore, the inhibitors of MAPK pathway could depress hPTTG’s transcriptional activity and its expression, indicating that MAPK pathway may regulate hPTTG. We also found that γ-synuclein contributed to the chromosome instability. hPTTG could be up-regulated by γ-synuclein, impling that hPTTG might participate in this chromosome instability progression related with γ-synuclein. hPTTG extensively effected on some important tumor-related genes, it increased expression of oncogene cyclin D1 and anti-apoptosis gene survivin, inhibited Gsk3β kinase activaty, and binded to p53.更多还原